# Amplifier Design - SQ Secrets Revealed



## thylantyr (Jan 21, 2008)

I'm inspired by the crazy Zuki threads to show you a twisted view on
audio. You will require concentration to see the meaning of this thread.
My delivery method of explaining things are odd, to allow the reader to think
about it.  :blush:  

http://www.createforum.com/petereuro/viewtopic.php?t=457&mforum=petereuro

Amplifiers are mystery. If nobody has tested it, nobody really knows
what it can do. Taking gut pictures only can reveal so much about
the amplifier.

If you analyze amplifier design, you will see that it's mostly recyled designs
as the core ingredients are the same.


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## FoxPro5 (Feb 14, 2006)

May we post gut pics for your analysis? Or is this tread about something else?


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## thylantyr (Jan 21, 2008)

Gut pics in conjunction with amplifier tests can really paint a nice picture.
You can only really compare two designs if only looking at guts. You need
something to compare with. You can post what you want.

Bink on the pro audio forum took the mystery out of proamps. People there
were talking crazy and speculating just like people do in car audio.

Once he published this;
http://home.pacbell.net/lordpk/bink/bink.jpg

Then there is less chatter on the forums as the scores are a picture
worth a thousand words.

Bink organized an event and had people meet and they all brought their amps
for testing, a big party.

Here he is in the middle as they hook up the beast, a 9kw QSC proamp.









Has anyone in car audio stepped up to the plate and organized such an 
event? This would pretty much remove all the mystery surrounding amplifiers.


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## FoxPro5 (Feb 14, 2006)

Is there any truth to the design idea of putting the input and output sections on either end of the amp for greater noise rejection? MacIntosh, Brax, and others use that design. 

Yet, on the contrary, companies like Genesis, Linear Power, Zapco use designs with connections all on one side. So that obviously doesn't seem to be necessary or anything.

Is either amp layout better for certain things than others??? 

What are your thoughts?


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## thylantyr (Jan 21, 2008)

*Is there any truth to the design idea of putting the input and output sections on either end of the amp for greater noise rejection? MacIntosh, Brax, and others use that design. *

This is a common design found in many amps. If you were to look at the
schematic design it would be drawn according to signal flow, an input stage,
vas stage, output stage and power supply. The printed circuit board layout
follows that flow also because it makes circuit board layout easy. 









*Yet, on the contrary, companies like Genesis, Linear Power, Zapco use designs with connections all on one side. So that obviously doesn't seem to be necessary or anything. *

The signal flow is the same, the input stage, vas stage, and output stage,
but the power supply is on the right side of the board. This methodology doesn't flow as well if you had to do printed circuit board layout because
the output of the amplifier has to come back to the other side.










If you keep the power supply section in it's own area, it's all good. All amplifiers do this, even a Pyramid amp. lol









*Is either amp layout better for certain things than others??? *

I was looking at these ideas recently.
http://www.createforum.com/petereuro/viewtopic.php?t=440&mforum=petereuro

I haven't done car audio in a long time and I haven't used car amps using
the latter methodology. Manville point out in that thread that installers like
to hook up all the wiring to one side of the amplifier vs. both sides, that is
the motivations behind that method and that method seems to bring up
more issues.

http://www.createforum.com/petereuro/viewtopic.php?t=440&mforum=petereuro

I think I would like to run those speaker wires away from the transformer.


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## FoxPro5 (Feb 14, 2006)

I hear the word "control" thrown around a lot on the forums. 

What does it exactly mean for an amplifier to "control" a driver? 

And what part of the amp design would make one amp superior over another with regards to such a thing (if it indeed is real.)??

Great thread, learning a lot. Thx for playing.


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## dvflyer (May 11, 2007)

thylantyr said:


> Has anyone in car audio stepped up to the plate and organized such an
> event? This would pretty much remove all the mystery surrounding amplifiers.


I believe Richard Clark still has a $10,000 amp contest going on.


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## yermolovd (Oct 10, 2005)

FoxPro5 said:


> I hear the word "control" thrown around a lot on the forums.
> 
> What does it exactly mean for an amplifier to "control" a driver?


I'm not sure if this is common, but i've seen one certain individual with an "audiophile" label printed on his ass attributing "control" to damping factor and religiosly recommending amps with d/f > 100 or something, just because it will not be sq if it's below. haha. jeeeeahh  

sorry for the short interruption. this is interesting.


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## FoxPro5 (Feb 14, 2006)

yermolovd said:


> I'm not sure if this is common, but i've seen one certain individual with an "audiophile" label printed on his ass attributing "control" to damping factor and religiosly recommending amps with d/f > 100 or something, just because it will not be sq if it's below. haha. jeeeeahh
> 
> sorry for the short interruption. this is interesting.


Sounds like a guy I should party with.  



> For virtually every amplifier made, the damping factor is easily high enough to prevent audible changes in the output signal.





> This means that as soon as you start to add anything between the amplifier and the speakers, the amplifier can not compensate for the added components. This means that the DF starts to fall as soon as you connect a length of speaker wire between the amplifier and the speakers.


http://bcae1.com/dampfact.htm


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## durwood (Mar 7, 2007)

Control to me means using an amplifier within it's power range and not clipping electrically. Once you start clipping, you are losing control. 

Headroom and dynamics is the name of the game. I beleive there are some posts from abmolech around here about his idea of how much power is needed.


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## thylantyr (Jan 21, 2008)

> I believe Richard Clark still has a $10,000 amp contest going on.


The RC challenge is different that what I mentioned.
I was mentioning that someone could do what Bink did
and do amplifier testing and make a database of the results
for reference, to know the actual power output etc.


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## thylantyr (Jan 21, 2008)

FoxPro5 said:


> I hear the word "control" thrown around a lot on the forums.
> 
> What does it exactly mean for an amplifier to "control" a driver?
> 
> ...


Very low damping factor can cause this perception, but
even a cheap amplifier won't be this low. Certain tube
amps may have low DF and may manifest problems with
driving woofers well. A competent amplifier design will
have good DF to drive the speaker. Long runs of speaker
wire [ie proaudio applications] can cause low DF because
of the cable resistance, but you may not perceive lack of
control.

I think the perception is mostly related to the real power
output of an amplifier. I have seen this before where
you take two amplifiers with a sticker on it that says 500 watts 
and you audition both amps. You perceive one ampliifer to have 
better control over the speaker. People assume the power output
is 500w for both amps. But I would bet money that the amplifier 
that is perceived to work better is higher in power.

Lets say the one amp tested at 350w [overrated], the
other one tested at 700w [underrated], naturally the 
power is 2x more than the cheap amp and you will think
it controls the woofer better, but it's because it's it has
more power.

Amplifier rating are really useless, the amplifiers need
to be tested properly and if you have this data available,
what was once a mystery is just common sense.


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## MadMaxSE-L (Oct 19, 2006)

I'm not so sure I really agree with this; just because the amp with more power seems to sound better, does NOT really mean that it can control the driver any better. I didn't use to put any thought into DF; but when I cwitched out my Audiobahn monoblock amp for my present Eclispe 4ch's, I noticed my bass instantly got much tighter and sounded just alot better overall. I have the gain turned all the way down, and even when I had the Audiobling turned all the way up( simply for a reference - I wanted to see how hard it would drive my 12's before I took it out...), it still sounded "boomy" and uncontrolled at any volume level. 

I just don't think overall power had much to do with driver control...

-Matt


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## MiniVanMan (Jun 28, 2005)

MadMaxSE-L said:


> I'm not so sure I really agree with this; just because the amp with more power seems to sound better, does NOT really mean that it can control the driver any better. I didn't use to put any thought into DF; but when I cwitched out my Audiobahn monoblock amp for my present Eclispe 4ch's, I noticed my bass instantly got much tighter and sounded just alot better overall. I have the gain turned all the way down, and even when I had the Audiobling turned all the way up( simply for a reference - I wanted to see how hard it would drive my 12's before I took it out...), it still sounded "boomy" and uncontrolled at any volume level.
> 
> I just don't think overall power had much to do with driver control...
> 
> -Matt


Oh boy, here we go!


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## MadMaxSE-L (Oct 19, 2006)

MiniVanMan said:


> Oh boy, here we go!


And what exactly is the rolls eyes for? I must have missed the rule where you were the only one who was allowed to form an opinion...

It farily straight forward; switch out an amp of higher quality for one with **** for quality, and you gain an improvement - what's so hard to believe?


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## thylantyr (Jan 21, 2008)

MadMaxSE-L said:


> I'm not so sure I really agree with this; just because the amp with more power seems to sound better, does NOT really mean that it can control the driver any better. I didn't use to put any thought into DF; but when I switched out my POS Audiobahn monoblock amp for my present Eclispe 4ch's, I noticed my bass instantly got much tighter and sounded much _better_ - not necessarily louder - overall. I have the gain turned all the way down, and even when I had the Audiobling turned all the way up( simply for a reference - I wanted to see how hard it would drive my 12's before I took it out...), it still sounded "boomy" and uncontrolled at any volume level.
> 
> I just don't think overall power has much to do with driver control or the "tightness" of the sound...
> 
> -Matt


1. Did you test both amplifiers properly to see the power
output ? If yes, what is the scores? If not, do you have
tested data from someone else who did a proper test?
if yes, what is the scores? If not, don't proceed to question #2 below.

2. Did you match the gains of both amps to make
sure the comparison was done at the same power level ?


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## MadMaxSE-L (Oct 19, 2006)

thylantyr said:


> 1. Did you test both amplifiers properly to see the power
> output ? If yes, what is the scores? If not, do you have
> tested data from someone else who did a proper test?
> if yes, what is the scores? If not, don't proceed to question #2 below.
> ...


It's not really important; if the sub moves more, it's getting more power It's not that hard to figure out.

And if you are following your argument for "more power = better DF", then if the Audiobahn was pushing the sub w/ more power(which it obviously was if the cone was moving more), then the Audiobahn should have had a better DF...


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## thylantyr (Jan 21, 2008)

> It farily straight forward; switch out an amp of higher quality for one with **** for quality, and you gain an improvement - what's so hard to believe?


The word high quality has very little meaning.

Look here; 

You can argue that these are high quality.
http://www.higherfi.com/amplist/amplist.htm

OTELLO


> The first, concrete result of this new technology is represented by the fabulous OTELLO, a dream machine in which the charm of the thermionic tubes is married with the most modern technologies; an OTL with 6 transformers, with adjustable polarisation, without any type of feedback;
> 
> an amplifier with zero damping factor that has the fastest and articulated bass that anyone could hear.


1/2 of those amps fail when it comes to driving big subwoofers, yet the quality is superior. You can migrate
to a high quality amplifier to a cheap low quality car audio
amplifier and get better performance.


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## thylantyr (Jan 21, 2008)

MadMaxSE-L said:


> It's not really important; if the sub moves more, it's getting more power It's not that hard to figure out.


Explain why it's not important to know the real amplifier
power when designing a sound system ?

A subwoofer moving more doesn't mean much. What if
one amplifier had different signal processing than the
other ? 

Let go with this crazy idea. A low powered amplifier
driven by a DC coupled signal path from source to amplifier. You can perceive more cone movement than
a different design with higher power. What if it's not
DC coupled ? What if the high pass electronics is different?
Same thing.

There is also clipping, a low powered amplifier heavily
clipped can give a false perception.


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## thylantyr (Jan 21, 2008)

> And if you are following your argument for "more power = better DF", then if the Audiobahn was pushing the sub w/ more power(which it obviously was if the cone was moving more), then the Audiobahn should have had a better DF...


DF and power are seperate issues, don't combine them.
Right now, forget DF and just focus on power. Test some
car amplifiers and you will really see what they *don't*
do.


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## MadMaxSE-L (Oct 19, 2006)

thylantyr said:


> The word high quality has very little meaning.
> 
> Look here;
> 
> ...


High_er _quality does in fact have meaning; especially when we're discussing the relationship between the Audiobahn and the Eclipse. We all know for a _fact_ that the Eclipse is a high_er_ quality piece then the other one. While simply referring to somethign as high quality may be subjective, judging somethign as _higher_ quality over somethign else can in fact be measured...


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## thylantyr (Jan 21, 2008)

thylantyr said:


> 1. Did you test both amplifiers properly to see the power
> output ? If yes, what is the scores? If not, do you have
> tested data from someone else who did a proper test?
> if yes, what is the scores? If not, don't proceed to question #2 below.
> ...



If you want to improve your audio knowledge then you
need to answer the questions above. You said you didn't
have to measure amplifiers, I take the response as a no.

Since the answer is no, there is no more reason to continue this discussion on 'woofer control'. If you come back with data, we can continue.

For now, lets move on to the next topic.


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## MadMaxSE-L (Oct 19, 2006)

thylantyr said:


> DF and power are seperate issues, don't combine them.
> Right now, forget DF and just focus on power. Test some
> car amplifiers and you will really see what they *don't*
> do.


Um, no **** - that's why I replied in the first place - it seemed as though yu were saying that power had more to do with driver control than DF. If you'll notice, I posted this;



MadMaxSE-L said:


> ...I'm not so sure I really agree with this; just because the amp with more power seems to sound better, does NOT really mean that it can control the driver any better...


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## FoxPro5 (Feb 14, 2006)

Mr Thylantryr - 

I have no bench test (yet) on this amp, but it's rated to put out 83 x 8 @ 4 ohms (13.8v). It can be bridged down to 520 x 2 @ 2 ohms using the parabridge modules.

My amateur testing and experience with it tells me it's quite capable of its rated power at lower power (83 watts) but seems to run out of steam as its asked to do more and more.

I'm wondering if the engineers simply tried to cram too much **** into it and skimped out on the power supply. And as a result, it can't handle the high voltage demand. Just my theory. 

Can you tell by the pics if that might be true or not??


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## thylantyr (Jan 21, 2008)

> it seemed as though yu were saying that power had more to do with driver control than DF


Human perception of driver control is related to the power,
do some experiments you will see.


Your experience with migrating from one one amplifier to
another was probably due to a shift in power, from low
to high or high to low.

There is also the distortion variable not mentioned yet.
Migrating to high power high distortion isn't a good thing either. lol


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## thylantyr (Jan 21, 2008)

FoxPro5 said:


> Mr Thylantryr -
> 
> I have no bench test (yet) on this amp, but it's rated to put out 83 x 8 @ 4 ohms (13.8v). It can be bridged down to 520 x 2 @ 2 ohms using the parabridge modules.
> 
> ...


Is this the amplifier?
http://www.arkada.com/items/gravity8g1000.pdf



> Technical data
> RMS Output power in single mode @ 4 Ohms: 8 x 83 Watts
> RMS Output power in single mode @ 2 Ohms: 8 x 130 Watts
> RMS Output power in bridge mode @ 4 Ohms: 4 x 260 Watts
> ...


*Xetec Gravity 8G-1000 amplifier *
http://www.diymobileaudio.com/forum/showthread.php?t=8769


*Kindly be notice, Xetec germany is no longer & all product has been stop production since 1 oct 2006.. Now Xetec under 'LIQUIDATION'...*

http://www.gr8tunes.net/forum/showthread.php?t=7475

///////////////////////////////////////////////////////////////

I didn't read all those threads. It's a strange design that
you can take 4 channels and combine them into one channel of greater power into the same load. Has anyone
tested the claims? I know you can parallel channels
to drive a lower impedance but to get higher power in
the same load you have to raise the voltage somehow.

There is an unspoken way of 'bridging the already bridged
amplifier'. That's another debate.  

I'm not sure what they claim. Do they claim the plug in
modules have power or the modules config the amp?

The guts imply all eight channels are right on the board,
you can see the red inductor, perhaps the output coil for
each channel.

The FET driving the transformer look anemic for the
power claims, unless there is some secret stuff under
the board.

I would like to see the schematic as someone was really
focused on a certain design goal.


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## thylantyr (Jan 21, 2008)

> When an amp pushes a bunch of motors (high emf) and they make say, 113 db in the room, and the cones are flopping, (sounds crappy) then you switch to an amp with a similar power rating, that produces the same level, only this time the cones are moving cleanly with less visible excursion and the sound is tighter, is that only because you are putting more voltage in?


Is this a random hypothetical or a real test you did?

If test then -> Go back to Post #16. 

If hypothetical, then what do you want me to say when
you made up this scenario ?

I could tell you that the amplifier ratings are useless,
go test the amps, I could also say that the majority
of amplifiers are not DC coupled, they have a high pass
filter unbeknownst to the average consumer. This is a
variable on perception of 'woofers behaving badly' aka
Girls gone wild.........  

Most people that do ported subwoofers or PR's will have issues with cone 
movement and many of those systems are not DC coupled, it 
would only make matters much worse. These systems require precsion high pass 
circuits to function properly when you get into these types of designs. In car audio, 
I don't think people tune this low so imagine if they did, how much worse things can get.
That's just an example, the problem can exist without that type of design.


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## capnxtreme (Feb 5, 2008)

thylantyr,

Are you implying that the only amp specs that matter to our ears are power and distortion?


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## FoxPro5 (Feb 14, 2006)

thylantyr said:


> Is this the amplifier?
> http://www.arkada.com/items/gravity8g1000.pdf


Yes, and the manual and specs are correct.

The company is defunct. The amp was built by Chunglam overseas. 

The review you posted is mine.



> It's a strange design that
> you can take 4 channels and combine them into one channel of greater power into the same load. Has anyone
> tested the claims?


Yes, the amp does everything it says it does very nicely. There are separate gains for each amp (8 total). If you look at the manual, you can see how the modules essentially combine (parabridge) those channels together to gain more power. So no, the modules don't have power...they're just jumpers basically. Max rated power is 1040 watts (260x4 or 520x2). 



> The FET driving the transformer look anemic for the
> power claims, unless there is some secret stuff under
> the board.


What exactly is that and where is it located? :blush:

It's just kind of a mystery amp to me and I'd love to have someone that knows their **** tear it up...find its weaknesses....and strengths.


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## thylantyr (Jan 21, 2008)

> What exactly is that and where is it located?












That's the weird part. Lets assume there is no secret parts
under the board. The power fets are probably those devices
under the small peice of metal acting as a clamp with a
screw. It's hard to tell with that pic. If so, where's the
heatsink for these parts? Are all those all FETS? or just the 
edge ones that may be heatsinked? Are the other devices
under the clamp power supply diodes?

This is just a weird design. Engineering gone wild? It's
the only car amp I've seen in a long time that would spark
interest in gutting it down to see what makes it tick.

Even a power test can reveal somethings. If you have
it, then use it. It if blows up, then examine it.


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## FoxPro5 (Feb 14, 2006)

thylantyr said:


> If so, where's the
> heatsink for these parts? Are all those all FETS? or just the
> edge ones that may be heatsinked? Are the other devices
> under the clamp power supply diodes?


The amp is pictured laying upside down with the bottom cover off. On the top, you have the gain controls and the module slots.

There's about 1/4" between the board and the heatsink. Directly under the metal clips that you mentioned on the other side of the board, I count 4 FET's per clip that are heat-sinked. The rest are along the rails on either side.


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## thylantyr (Jan 21, 2008)

The question was if the power supply section can support the 1kw claim.
Looks like two power supplies, proably 500w+ each. If there is FETS
under the board (T0-220 package?), then the power supply seems fine for
the design. I want to know why they bridge all four amps sections into one
to get more power at the same impedance as the single channel. I never seen
a design that does more than 2 channels. Assuming discrete output stage
design, the guts imply only 2 power transistors per channel, the bare minium,
a risky design for it's power rating.


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## durwood (Mar 7, 2007)

I think it's easy for some people to equate control with clipping/compression and not realize it, because it can sound more controlled sometimes...depends on what the amp does when it reaches the limit of the power supply.

If you have experience with different amps from different era's it's not hard to figure it out.

When an amp clips it can do many things:

1) Distort
2) Compress
3) limit/clips


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## FoxPro5 (Feb 14, 2006)

thylantyr said:


> The question was if the power supply section can support the 1kw claim.
> Looks like two power supplies, proably 500w+ each. If there is FETS
> under the board (T0-220 package?), then the power supply seems fine for
> the design. I want to know why they bridge all four amps sections into one
> ...


Can't tell if they are T0-220's or not. 

Risky, how so?

As a comparison, I liked to put this amp up against another similar-speced (sorry, not actually measured) that I've used quite a bit, the two channel used in the DLS Ultimate amps.

The A2 is rated at 85 x 2 @ 4 (13.8v). 

I've gone back and forth between the Xetec and the DLS and level matched and they are essentially indistinguishable. I guess what gets me is Xetec managed to get on those little boards what DLS has to use an entire heatsink for. No, obviously the amps are not the same....and the DLS is more capable in terms of power, but for my own personal use I find it interesting.

Ok, maybe not that fair of a comparison. No preamp on the Xetec, for one. 










Anyway, thanks for the feedback...I'll stop rambling now.


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## thylantyr (Jan 21, 2008)

*re: Xetec Gravity 8G-1000 amplifier *


////////////////////////////////////////////////////////////////////////////
Simplified;

83W @ 4 ohm per channel
130W @ 2 ohm per channel

Use channel 1&2 in bridged mode = one channel @ 260W @ 4ohms
Use channel 3&4 in bridged mode = one channel @ 260W @ 4ohms
////////////////////////////////////////////////////////////////////////////

Above is nothing new. That's how all amplifers work if they have a bridged
mode option.

This amp goes one step further. 

Parallel 'channel 1&2' combo with 'channel 3&4 combo' to drive a 2 ohm load
now @ 560 watts.

Parallel amplifiers are not common, but I first seen this in some of those
JBL car amps. I don't know who else did this in car audio. I also know that
Nelson Pass had some amps for home audio that could be paralleled, his
X1000 [1kw] was said to be able to have 32 amplifiers in parallel for 32kw.

I wasn't sure about this Xetec Gravity amplifier so I went on DIYA to ask, and oddly,
Nelson replies... 



> If you run the channels series and parallel, you can quadruple
> the output even into as low an impedance as a single channel
> would drive. I've done it a few times, and it works like glue


Someone linked the 'chipamp' datasheet. I knew about the bridged parallel
option as seen in chipamp designs but I was wondering this this Xetec Gravity
amplifier was discrete or chipamp? Any ideas by looking at the guts? 

See figure 13.
http://www.national.com/an/AN/AN-1192.pdf

It seems though that compromises were made to allow this flexibility.
The output stage per channel isn't robust from a first glance.


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## MiniVanMan (Jun 28, 2005)

MadMaxSE-L said:


> And what exactly is the rolls eyes for? I must have missed the rule where you were the only one who was allowed to form an opinion...
> 
> It farily straight forward; switch out an amp of higher quality for one with **** for quality, and you gain an improvement - what's so hard to believe?


The roll eyes is for the next few posts that followed this one where Thylantyr basically told you to put up or shut up. Since you didn't put up, I see that you shut up. That's at least good.

Why I laughed at your statement which precluded the  was that you stated that you didn't believe Thylantyr when he said that a higher power amplifier will control a speaker better than a lower powered one. Then you come with a comparison between Audiobahn and Eclipse and state without any empirical data that the Audiobahn puts out more power than the Eclipse. However, the Eclipse sounds better, and is higher quality. Again you state this without any empirical data, except the subjective opinion that the Eclipse sounds better. 

So, in the end, do you think that maybe the Audiobahn might be overrated? Naaaahhhhh! Audiobahn has always been on the up and up when it comes to rating their equipment. I apologize as this evidently offends you, but I can't help myself


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## thylantyr (Jan 21, 2008)

> where we've got four basic schools of thought:
> 
> Mosfet vs. bipolar vs. chip
> 
> ...


This is too complicated. Think simpler. The goal is to catch a rat,
ask 100 people to catch a rat and they have 100 different rat traps,
but eventually as people analyze those traps they get fond of certain
designs.

For audio amplifiers this is cake. It's easy to make an audio amplifier
because 20khz is an easy goal. This goal has not changed as humans
have not changed.

To compare, go back 20 years and look at the personal computer. Because
the goals are not limited to the human's limitations, the computers make
big advancements in processing power.

You can easily reach your audio goals with either mosfet, bipolar or tube,
some designs are easier to execute. The transistor topology is just a mechanism in the rat trap. The 'TO3 vs. 220 vs. 247' is a simple issue,
each transistor case has thermal ratings. You choose accordingly for the
design. Don't think of it as *one* TO3 vs. TO220[/b], think if the whole
design.

Example;

I see 10 TO-3 metal can transistors mounted on a piece of angle iron
which is fastened to the main heatsink.



















Ask yourself this;

*Question 1*
What if I cloned that design but changed the metal can transistors to TO3P [plastic, ie TO-247] ?

Can I get better thermal performance if I tweak the design ? I think you
can.

First issue is this. The metal can is mounted on a thin piece of angle iron
and the angle iron is mounted on the heatsink.

Transistor -> insulator -> thin metal -> angle -> heatsink

What is the best method?

Transistor -> heatsink

You elminate all the stuff you don't need that hinder heat transfer from
the transistor to the heatsink.

But you can't directly connect the transistor to the heatsink is this mechanical design of the amplifier so you need an insulator.

Transistor -> insulator -> heatsink

*Question 2*
A single TO-3 metal can is better thermally than a single plastic package.
I get I can install 16 TO-3P's vs. 10 metal cans. Plus, since the plastic
transistors can be mounted vertical directly on the heatsink without using
the stupid angle iron, this design will be an improved design.


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## FoxPro5 (Feb 14, 2006)

thylantyr said:


> Someone linked the 'chipamp' datasheet. I knew about the bridged parallel
> option as seen in chipamp designs but I was wondering this this Xetec Gravity
> amplifier was discrete or chipamp? Any ideas by looking at the guts?
> 
> ...


I looked at that and I might as well be reading Japanese. :blush: Sorry, I have no clue.

Thanks for the great groundwork. You really know how to dig.


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## FoxPro5 (Feb 14, 2006)

Ok, one more question now that I had my camera out.

I know Zed offers a Burr Brown chip(s) as part of a "SQ upgrade" in his amps. So , while I had my A2 out, I snapped a pic of the BB chip on the board:










If you can't quite make it out, it says BB OPA2604 AP

That thing is tiny! What exactly does it do and why should I pay extra for it??


----------



## Xander (Mar 20, 2007)

thylantyr said:


>


I was going to say, that looks just like my old school Orion Hott Setup 2.125. Then I just noticed the link is an Orion amp... go figure... I love my amp but it keeps crapping out on me


----------



## thylantyr (Jan 21, 2008)

FoxPro5 said:


> Can't tell if they are T0-220's or not.
> 
> Risky, how so?
> 
> ...



What I mean by risky is how well an amplifier is over-engineered. It seems
that the 8ch amp has only two transistors for each channel in the output stage, 
the mimimum 'normal' is four transistors like the DLS amp and every else.


----------



## thylantyr (Jan 21, 2008)

FoxPro5 said:


> I looked at that and I might as well be reading Japanese. :blush: Sorry, I have no clue.
> 
> Thanks for the great groundwork. You really know how to dig.


It's easy. Look at figure 13.
http://www.national.com/an/AN/AN-1192.pdf

On the right is a speaker symbol. Follow the wires to U1, U2, U3, U4,
those are the outputs [opamps].

Look at the U1 and U2 blocks, they are identical blocks.

The circuits near U1 belong to U1. That U1 block was copied
as U2. U1 is the same circuit as U2. Two of them.

U1 and U2 outputs are tied together - parallel mode.

Simple ?

U3 and U4 are inverting blocks, each identical and in parallel.

Parallel gives you more current.

Now bridge those two sections together [U1/U2 modules] bridged with
[U3/U4 modules]

U1/U2 module = akin to push
U3/U4 module = akin to pull

That's the general idea. Ignore all the small circuits and think in
terms of a block diagram.


----------



## thehatedguy (May 4, 2007)

2604 is a pretty good BB opamp. Only thing better in a dual package from BB might be the 2227 and 2107- the 2107 is basically a dual version of the 627 and is the most expensive dual opamp BB makes, about $12 each compared the $4 or so for the other.

Opamp= operational amplifier. It's the discrete stuff all on a chip. Your transistors amplify the signal coming from the ship. the PS feeds those transistors.


----------



## thylantyr (Jan 21, 2008)

FoxPro5 said:


> Ok, one more question now that I had my camera out.
> 
> I know Zed offers a Burr Brown chip(s) as part of a "SQ upgrade" in his amps. So , while I had my A2 out, I snapped a pic of the BB chip on the board:
> 
> ...



Opamps are great. They are the building blocks of analog design used
for everything, from analog preamps, EQ's, crossovers, even chipamps....etc..........
http://www.bcae1.com/opamp.htm

People write books and have tons of designs for these opamps.

The OPA2604 is just another opamp optimized for audio. Some opamps
are optimize for other tasks. There are many good opamps for audio,
audio is a simple thing in relation to how complicated electronics can get.

For instance, Zapco was pushing the envelope and being bold by using
NE5532 opamps, they probably cost $5 - $8 each in single unit pricing
when the early Zapco's came out. Other companies many have used
stuff like TL072 opamps.

What is the difference? Each opamp has a datasheet and if you design opamps circuits, it's your job to know the limitations of the opamps and
work around it.

Many people in audio+electronics will focus too much on the individual opamp
and analyze that one single item. They never analyze the whole design and
see it it works. Analogy would be like looking a some nuts and bolts used
to hold your car together. You can get a bolt used in a Ford truck and
compare it to a bolt used in a GM truck and find the better bolt, but people
never look at how the bolts are used to build the truck.


Douglas Self is fanscinated with the topic of amplifier distortion as if we
can hear parts per billion distortion and he writes books on amplifier design
and analyzes opamps.

http://www.dself.dsl.pipex.com/ampins/webbop/opamp.htm

TL072
http://www.dself.dsl.pipex.com/ampins/webbop/072.htm

5532
http://www.dself.dsl.pipex.com/ampins/webbop/5532.htm

OPA2604
http://www.dself.dsl.pipex.com/ampins/webbop/opa604.htm

OPA2134 has been the boner opamp for a long time now.
http://www.dself.dsl.pipex.com/ampins/webbop/2134.htm


> Here is a look at a more recent opamp design, for comparison with the old faithfuls.
> The OPA2134 is a Burr-Brown product, the dual version of the OPA134. There is a quad version called the OPA4134. The manufacturer claims the OPA2134 has superior sound quality, due to its FET input stage. Not a particle of evidence is given to back up this assertion, which is most unfortunate.
> The two THD plots show the device working at a gain of 3x in both shunt and series feedback modes. It is obvious that a problem emerges in the series plot, where the THD is higher by about three times at 5 Vrms and 10 kHz. This distortion increases with level, which immediately suggests common-mode distortion in the input stage. This is ironical since this input stage is supposed to be a selling point.
> 
> ...



You can read the quick summary of each. Pros/cons. Good opamps for audio
are cheap now. You can probably get the NE5532 for 25 cents in bulk order.
OPA2134 probably a dollar in bulk order.

To satisfy the snobophiles, there an opampfor them too. OPA627 for
$30 each.  

http://www.dself.dsl.pipex.com/ampins/webbop/opa627.htm


> The OPA627 (Burr-Brown) is a very expensive opamp with excellent DC precision. But is it any good for audio? The answer is yes. Distortion is very low, though there are the usual problems with input common-mode distortion when series feedback is used.
> 
> The OP627 is a single opamp. No dual version is available. The OPA637 is a decompensated version only stable for gains of 5x or greater


It's not $30 good


----------



## thylantyr (Jan 21, 2008)

Xander said:


> I was going to say, that looks just like my old school Orion Hott Setup 2.125. Then I just noticed the link is an Orion amp... go figure... I love my amp but it keeps crapping out on me



This one? [Made by Orion]
http://ampguts.realmofexcursion.com/The_Hott_Set-Up_HS_2.125/

These are ~20 year old designs. Are you driving it too hard ? These
amplifiers do have limits.


----------



## durwood (Mar 7, 2007)

thehatedguy said:


> 2604 is a pretty good BB opamp. Only thing better in a dual package from BB might be the 2227 and 2107- the 2107 is basically a dual version of the 627 and is the most expensive dual opamp BB makes, about $12 each compared the $4 or so for the other.
> 
> Opamp= operational amplifier. It's the discrete stuff all on a chip. Your transistors amplify the signal coming from the ship. the PS feeds those transistors.


Foxpro-

the opamps are smaller versions of transistors. The don't handle the big current stuff but provide simple gain stages and are also used in every electronic active crossover. Which one you pick depends on design goals. I have a pile of the ones thehatedguy mentioned that I can swap out on my soundcard to give you certain "sonic signatures", but it is very minor. They are the pre-amp's. Another popular one is the national LM4562. I would have to dig through the spec sheets for each one, I don't remember exactly why I picked each one up, but they do vary slightly between them. If you were to look at the details of each chip, it would look like a tiny complex amp all on their own.


----------



## FoxPro5 (Feb 14, 2006)

So they are like tiny amps that tell the rest of the amp what to? :blush: Thus the proximity to the signal inputs? It's like the first chip inline on my A2. 

Say I swapped my 604 for that $30 baller op amp, would I be pimpin some SQ watts or what?  

I got Steve M on the phone selling me up $100 on his BB upgrade. In all likelihood, is that a reasonable investment knowing what it *can* do??? Or should I say "thanks, but no thanks Steve" and buy that fancy Dashmat instead.  Know what I'm saying?


----------



## durwood (Mar 7, 2007)

FoxPro5 said:


> So they are like tiny amps that tell the rest of the amp what to? :blush: Thus the proximity to the signal inputs? It's like the first chip inline on my A2.
> 
> Say I swapped my 604 for that $30 baller op amp, would I be pimpin some SQ watts or what?
> 
> I got Steve M on the phone selling me up $100 on his BB upgrade. In all likelihood, is that a reasonable investment knowing what it *can* do??? Or should I say "thanks, but no thanks Steve" and buy that fancy Dashmat instead.  Know what I'm saying?


Mmmm, I'm not a fan of dashmats, but it soley depends on your install. Invest in proper physics and acoustic theory over minor electronic upgrades.

But yes, the opamp is usually the first guy inline waiting to greet your "SQ" (sarcasm) signal 

Do you really need fresh spring water when tap water is all you really need? (I know you should understand this one foxpro)


----------



## thylantyr (Jan 21, 2008)

*thanks, I do understand that about those transistor choice decisions, based on thermal stability, but why is it that there's such a following for TO3 metal cans in car amps?*

Maybe they are following the wrong thing. Maybe they should follow
the good amplifiers and not the nut or bolt used ?

Lets look at this because it's an extreme example.
http://www.accuphase.com/model/pdf/m-8000_e.pdf

44 plastic transistors for one channel. Lets say your job is to convert
the design to metal can. How would you do it? You would need a
metal interface block to mount the metal cans at an angle, Linear Power
style;










You lost 1/2 of the number of transistors as you can only fit 1 metal
can for every 2 plastics. That's a downgrade in total performance.

You also have a metal interface bar to transfer heat, not ideal. You
want the transistor right on the heatsink.

*I'm more interested in why the sound quality is perceived to be better in old Linear or Lunar or Tru or MMAts, etc.? *

Which amplifiers have been compared? A Ford vs. Ferarri or Lexus vs. Mercedes?   



> Is it because the designer has to work within lower dissipation limits, and therefore is more conservative with the output characteristics?
> 
> I broke it down according to type, circuit configuration, physical parameters, and brand.
> 
> This is what I would like to know, what's the truth behind complementary symmetry, darlington, going big, Japanese sand, lol..



Marketing > Engineering. Look at that M8000 home amp. Try to convince
your boss who owns an amplifier business to make that design for car
audio, because you think it would be cool.......... You probably made a protoype in the garage and it will never make it to being produced.



> Anyways, it's just fun seeing what people acknowledge is good stuff, Burr-Brown op-amps, Wima Caps, Piher pots, Nichicon, polypropylene, mylar, air foil, I feel like I'm stuck in a bad Billy Joel song, We didn't start the fire....


John Curl's designs are influenced highly by public perception. He needs to
add the stuff in his amplifier designs that willl sell product. If they want
a Black Gate cap for a certain product, he will install it because people want it.


----------



## thylantyr (Jan 21, 2008)

*I got Steve M on the phone selling me up $100 on his BB upgrade.*

Steve M was on the forums years ago when he introduced his new line of amps. When 
questioned about the upgrade, he said he can't hear a difference. That is good news, that 
means he did a proper job at circuit design with the low cost opamp.

Do you see what is going on now ?

If there was a noticable SQ improvement then the core circuit design of
said design raises a flag.


----------



## Dillyyo (Feb 15, 2008)

thylantyr said:


> Human perception of driver control is related to the power,
> do some experiments you will see.
> 
> 
> ...


Didn't he say" it still sounded boomy even after I turned the gains all the way up"!


----------



## thylantyr (Jan 21, 2008)

To clarify, opamps are a tool. Not everything electronics will use them.
Home audiophiles frown on opamp useage as they prefer simple gain block
designs using transistors, the minimalist approach. They seem to fear the
chance that a circuit design is a failure. If so, why not have the amplifer
tested to easy their minds? They don't because they don't understand.
Car amps, proamps, they are loaded with opamps. 

Here's another skinny. If you follow Nelson Pass and his journey he might
tell you that when he go into audio it was a path of simplicity that lead
to more complex designs and now he's back into building simpler 2 stage
amplifiers and raking the money on awesome build quality and I think he
has a nice niche to inhibit amplifier cloning. 

Why go from simple to complex to simple? Because none of it was audible.

That is my weird take on it.


----------



## thylantyr (Jan 21, 2008)

cajunner said:


> I see you equate number of transistors to be an indicator of performance in design, is this because you gain stability as you pair them off, (cram them in, vs. using larger and less) and sound quality is improved, or is it one and not the other?


/Random

IRFP240 mosfet
http://www.tranzistoare.ro/datasheets3/fairchild/IRFP240.pdf

* 20A, 200V device.
* Maximum Power Dissipation 150 watts.

People say .. oh.. 20A device, 200v, 150 watts.. sweet.
They don't investigate further to understand the real story.

/////////////////////////////////////////////////////////////////////////////////////

Look at figure 3 

20A is @ 25 degrees case temperature. As the transistor gets hot, the 20A
rating falls like a rock. If that transistor go to 150 degrees, it's useless.

What if you use many transistors to distribute the load ? Can it yield better
performance ?  instead of trying to use one transistor to do all the work.

Search DIYA archives, Nelson Pass said this about that transistor


> The device is rated at 150 watts at a 25 deg C case temperature,
> derate at 1.2 W per deg C.
> 
> I like to run them around 25 watts, and I have run them as high as 50 watts
> without excessive failure rates, but this is heat sink dependent.



If you were going to design a big power amplifier it would be ideal to
use a big bank of transistors to keep the temperature per transistor low
and you need to make sure your heatsink is up to the task. These variables
are chosen by the designer to meet the design goals.


*IRF240 - TO3* 
* 18A, 200V device. 
* Maximum Power Dissipation 125 watts. 

It's your turn to look at the finer details of this metal can vs. the other plastic one.


----------



## thylantyr (Jan 21, 2008)

Another link to check out.
http://sound.westhost.com/heatsinks.htm#introduction

Consumers love metal case transistors for the bling bling.
People designing circuits will choose the correct transistor
for the job, regardless of what transistor case it is. A metal
can transistor like TO-3 is just a case. The actual transistor
is a small die mounted on it. Remove the lid of the TO-3
and it's empty space. It's a die on a piece of metal just
like any other power transistor is. The cases have ratings
as described in the link. The part that people choke on is
they look at only one specification and form a conclusion.

The real issue is that you shouldn't design a circuit where
the transistor operates hot because it can hinder
performance. You may see exotic amplifiers with banks
of multiple parallel transistors and great heatsinking to get
better performance because they can distribute the load
evenly across each transistor. More can be better.

Designers that talk about their amplifier design, less = best, 
only want to paint a picture in their favor and never
tell you the whole story. The reason they use less is because of 
business decisions. When you are are in a bind and can only use 
4 power transistor per channel, you are handcuffed and you have 
to find the best solution for that job and the choices may be narrow.

On the other hand, if you came back and told the marketing clowns 
that you need 8 transistors to make a better design, using lower cost 
parts, but increasing the amplifier size a bit, they'd probably fire you
unless you can convince them there is cost savings 

re: Darlington
http://en.wikipedia.org/wiki/Darlington_transistor

This is a different topic. The darlington is not related to
paralleling transistors as we've been talking about.

Darlington is a configuration of transistors, it can be
all discrete or they can be in part of the single transistor.

This is just a 'gain' issue. It's nothing special to see.

Check this out. 2N6045 darlington
http://www.ortodoxism.ro/datasheets2/a/0se2cqtiflspldga894ikp2s2spy.pdf

I use to use these for car audio projects because I
got them cheap at the surplus store. I needed to drive
those relays using a small input signal, lets say from
a digital integrated circuit with low current. The darlington
makes sense because it has high gain. I can buy one transistor,
a darlington or I can buy two transistor, a regular transistor that
drives the relay, then a second small signal transistor in a darlington
config to be the input side. Why bother, just get a darlington.

If you see amplifier that hype up darlington useage in their
amplifiers, then I would laugh at the marketing people for
being silly. You might as well hype up the blue anodized heatsinks
as being a key feature.


----------



## thylantyr (Jan 21, 2008)

> interesting about the bling, I don't know what would cause anyone to use a transistor that takes up more space and doesn't have any redeeming qualities other than it looks cool and can be marketed differently, but maybe that's enough.


Random TO-3 babble here. 
http://www.createforum.com/petereuro/viewtopic.php?p=4054&mforum=petereuro#4054

Nelson [www.passlabs.com ];


> The TO-3's are prettier, and they hold up better in corrosive
> environments, but that's about it.
> 
> snip...
> ...



Grollins said;


> Given that the TO-3 case is slowly being phased out, the question is moot.
> The favored piece is the one that's available.



I remember reading somewhere that the military wanted this type of
transistor packaging in ancient times and if you know a thing or two about
the military, they have very strict specifications for semiconductors. Companies 
making semiconductors have to follow these tight regulations
and screen out only the best parts and the military would pay big premiums
for this. Example, a semiconductor chip may be tested at 125 degrees C
and must pass to be a military part whereas a consumer part may only need
to pass 25 degrees C, some industrial grade parts may be tested at 80 degrees C. 
You get the idea, the military is anal...... There is more to a military part than just
temperature testing.

Naturally, since the TO-3 package is an old workhorse, people remember it well and 
like it and it does work. But given the nature that these may be phasing out and plastics 
have nice performance and lower cost, maybe it's a better choice. 



> why is it only certain amps prevail in sound quality competition?


There is not such thing as an SQ contest. Think about it. If you believe SQ can't be measured,
then don't worry about who uses what equipment.

Check this out, SQ contest rules.
http://www.createforum.com/petereuro/viewtopic.php?t=432&mforum=petereuro



> A USACI competitor’s audio system’s sound quality will be judged according to the rules and guidelines in this section.
> 
> *POWER SOURCE DESIGN, Wiring, SIGNAL SOURCE AND
> PROCESSORS, SPEAKERS, AMPLIFIERS, ATTENTION TO DETAIL,
> ...


Even if SQ could be measured [but it can't], what does the *install bling* have to do
with sound quality ?


----------



## Fixtion (Aug 25, 2006)

*statement*

i appreciate all the research and knoweldge sharing. i feel though perhaps we understand the flaws of modern amp design through your examples.

instead of continuing to run circle with pointing out the bad, let turn this into a productive listing of amps done correctly.

provide a list of car audio applicable amps, starting from most correct design to least.

this will give us whom don't have background in this topic to identify with visual comparisons.

thank you.

*-fixtion*


----------



## Oliver (Jun 25, 2007)

Fixtion said:


> *statement*
> 
> i appreciate all the research and knoweldge sharing. i feel though perhaps we understand the flaws of modern amp design through your examples.
> 
> ...


This would be really hard to do, unfortunately.

When something does not work , we analyze what the problem is or was.

When something works , we don't ask any questions.

If something kinda works or is "marginal" , so to speak ,we make exceptions to our rules of what will work [ and what won't work ].

I have heard it said: 'Democracy is the worst form of government [ after every other form of government ],


----------



## thylantyr (Jan 21, 2008)

Fixtion said:


> *statement*
> 
> i appreciate all the research and knoweldge sharing. i feel though perhaps we understand the flaws of modern amp design through your examples.
> 
> ...



Everyone has their own thoughts on what is an audio amplifier done correctly.

Here is my general feeling. You test as many amplifiers as you can and
develop a database so people can see the scores and find the amplifier that
might fit their application.

* Test the amplifier frequency response to it's frequency response spec.

* Test the amplifier using 1% THD+N distortion as the reference because
this amount of distortion is widely accepted as inaudible even by audiophiles,
this will give you the higher power score which is what we want to know.

* Test the amplifier @ 14.4v input, then do a 'sagging' voltage test, maybe 
9 or 10 volts.

* Test @ 20hz, 1khz, 20khz.

* The test should be an 'RMS test method', a big bank of non inductive
resistive loads that hold their resistance value to about +/- 3%.

* Do a burst test, maybe 25mS - 50mS.

* The test should be done at ambient room temp, maybe 70 degrees?
Initiate the test and record the highest score.

* Test at 4 ohms/ch, and also test as the lowest rated impedance, ie
2 ohm/ch, etc.

* Do a torture test to see how long the amplifier will operate at nominal
impedance before going into thermal protect. If the amp didn't go into
thermal protect after 1 hour or so, stop the test. Do the same test
as the lowest impedance.

* Take the heatsink temperate during the torture tests.

* Optional, calculate amplifier efficiency.

Did I miss anything?


When the database is getting large we can then look at the data and sort by the best performing
amplifiers in their real power class. We can look at the amplifier in detail to see what they
did better to get a higher score.


----------



## Oliver (Jun 25, 2007)

If it can do what you need, for as long as you need[BUY IT] 

I personally like the sagging voltage part[ this is what counts, big time ]IMHO


----------



## Fixtion (Aug 25, 2006)

okay, next step.

who has the means, and who's willing to donate their gear?

*-fixtion*


----------



## t3sn4f2 (Jan 3, 2007)

a$$hole said:


> If it can do what you need, for as long as you need[BUY IT]
> 
> *I personally like the sagging voltage part[ this is what counts, big time ]IMHO*


x2, thats why I go by 12 volt ratings for the power estimate I want, stay below 90% of rated power no matter what, and go with a low resistance battery that will act like a 12 volt 1000 amp alternator anytime its needed.


----------



## thylantyr (Jan 21, 2008)

thylantyr said:


> Gut pics in conjunction with amplifier tests can really paint a nice picture.
> You can only really compare two designs if only looking at guts. You need
> something to compare with. You can post what you want.
> 
> ...



Repost: This what the car audio folks need to do. Get together, get organized and get smart   

This is 'Bink' btw.............
http://www.binkster.net/

Chuck on the AVS forum (home audio) started to do some more amplifier testing to add to the database, but Chuck is not adopting 'binks' methods
exactly and can't do a sagging voltage test, but nonetheless that data is
good data vs. nothing.

The thread is hear. We discuss issues. Some of those issues apply to
car audio amps.

*Measuring Amplifiers *
http://www.avsforum.com/avs-vb/showthread.php?t=855865

You will need a heavy duty resistive load like these.
http://s272.photobucket.com/albums/jj168/thylantyr/load/


----------



## Oliver (Jun 25, 2007)

Statement modified to reflect what everyone is waing for  how long does it take ?


thylantyr said:


> I'm inspired by the crazy Zuki threads to see how much power it makes.
> 
> Amplifiers are mystery. If nobody has tested it, nobody really knows
> what it can do. Taking gut pictures only can reveal so much about
> the amplifier.


How is the testing going ? I've seen some pictures [Thank You Crazy8 ], how are the guys doing who bought one to "expose" the truth ?


----------



## Oliver (Jun 25, 2007)

The animals are getting restless as evidenced here 

I was referring to those that come here and want to be spoon fed. When DIYMA first started, there were A LOT of new explorers...just as there are now. However, we didn't go around wining and bitching if someone didn't have the answers for us. We (and I say "we" as sort of a collection of dudes interested in the same thing) learned just as NPD has said, via trial and error.









I can think of a couple of people that are interested in the results !










Let's go , already!!!!


----------



## thylantyr (Jan 21, 2008)

a$$hole said:


> Statement modified to reflect what everyone is waing for  how long does it take ?
> 
> 
> How is the testing going ? I've seen some pictures [Thank You Crazy8 ], how are the guys doing who bought one to "expose" the truth ?


I left car audio in ~1992  

Home audio is where I'm at.

Because the two have things in common, I visit both forums and throw out
a bone. People who are into car audio need to get together and remove
some of these mysteries that haunt every forum. If they don't, oh well....  

I know this place existed years ago and I'd visit once on a while, I just happend to
get un-lazy and register recently. lol


----------



## Oliver (Jun 25, 2007)

thylantyr said:


> I left car audio in ~1992
> 
> Home audio is where I'm at.
> 
> ...


Did the OP from "Zuki Revieled" , smgreen20 ,I think his name was post the results of that bunch of guys who bought one ?


----------



## Oliver (Jun 25, 2007)

This guy ever make good on his promises ?

1 Week Ago #9 
smgreen20 
DIYMA Novice


Join Date: Oct 2006
Location: Lafayette, IN
Posts: 52 


iTrader: (0)


----------



## WRX/Z28 (Feb 21, 2008)

Concerning the discussion of dampening factor. I know back in the day when I worked for a kenwood dealer, we had an awesome accomodation program on this amp among other things. 

http://www.kenwood-electronics.com.my/imanual/b64-1441-00_kac-ps401m.pdf

The sigma servo circuit was said to increase dampening factor from 500 to something like 9,900. I hooked it up on an old school eclipse aluminum 15", with it activated, the sub sounded tight as tight can be, even being a 15" sub. De-activated/disconnected, it sounded noticably sloppy. Psycho-acoustics? Maybe, but I don't think so. It seemed to make an audible difference. Did it sound bad without it? no. Did it sound better with it? I think so. Anyone care to explain? In this case, the amplifier, and it's power level are identical because it's the same amp and it's the same sub. The only change was in dampening factor capabilitys. In my mind, this proves that dampening factor has some bearing on tightness of sound.


----------



## Oliver (Jun 25, 2007)

I pm'ed smgreen20,

Maybe he forgot the "Zuki Revieled" promises    

Reminds of a Steve Martin movie, "The Jerk" , ...the new phone books here...I'm somebody


----------



## thylantyr (Jan 21, 2008)

a$$hole; I don't know what you are talking about. hehe
I'm not following any guy to see if he made good on promises.


----------



## Oliver (Jun 25, 2007)

Didn't you just post this ?

quote
Go to the forum and look at it. Every topic is game to analysis, ie I just
spent a week trying to uncover the Zuki mystery... 
end quote


----------



## thylantyr (Jan 21, 2008)

WRX/Z28 said:


> Concerning the discussion of dampening factor. I know back in the day when I worked for a kenwood dealer, we had an awesome accomodation program on this amp among other things.
> 
> http://www.kenwood-electronics.com.my/imanual/b64-1441-00_kac-ps401m.pdf
> 
> The sigma servo circuit was said to increase dampening factor from 500 to something like 9,900. I hooked it up on an old school eclipse aluminum 15", with it activated, the sub sounded tight as tight can be, even being a 15" sub. De-activated/disconnected, it sounded noticably sloppy. Psycho-acoustics? Maybe, but I don't think so. It seemed to make an audible difference. Did it sound bad without it? no. Did it sound better with it? I think so. Anyone care to explain? In this case, the amplifier, and it's power level are identical because it's the same amp and it's the same sub. The only change was in dampening factor capabilitys. In my mind, this proves that dampening factor has some bearing on tightness of sound.


Here's the formula.
http://en.wikipedia.org/wiki/Damping_factor

DF = Zload / Zsource

which is;

DF = speaker impedance / amplifier output impedance

If the amplifier has DF of 500 driving a 4 ohm woofer, then DF
is 0.008 ohms.

Imagine a black box, the amplifier, a voltage source, it has an output resistance of 0.008 ohms driving a 4 ohm woofer.

Black Box [amplifier, a voltage source] -> 0.008 ohms -> 4 ohms [woofer] 

Simplified;
*Battery with 0.008 ohms of internal resistance driving a 4 ohm resistor.*

To connect the battery to the resistor you used a hunk of 16 awg wire.

16 awg wire is rated for 0.004 ohms per foot. Lets say you ran 10 feet
of wire. 10 feet * 0.004 ohms = 0.04 ohms.
http://www.powerstream.com/Wire_Size.htm

Update:
Battery [0.008 ohms] + ten feet of 16 awg cable [0.04 ohms] -> 4 ohm resistor.


The battery alone was 0.008 ohms.
The battery plus wire is now 0.048 ohms, 6x higher.

Amplifier [0.008] + wire [0.04] --> 4 ohm woofer.

DF is now;

DF = Zload / Zsource

DF = 4 ohms / 0.048 ohms

DF = 83

Your DF = 500 dropped to DF = 83 by just hooking up some speaker wire.

////////////////////////////////////////////////////////////////////////////////////

REDO the math for DF = 10,000

The amplifier is now at 0.0004 ohms.

Add the speaker wire [0.04] and the new total is;

0.0004 ohms + 0.04 ohms = 0.0404.

DF is now;

DF = Zload / Zsource

DF = 4 ohms / 0.0404 ohms

DF = 99

From DF = 10,000, add some speaker wire and it's now 99.

Migrating from an amplifier with DF = 500 to DF = 10,000 doesn't do anything
because most likely the speaker wire used plays a role and people don't
look at it.


----------



## WRX/Z28 (Feb 21, 2008)

I guess that would work if speaker wire had a constant resistance for every type/guage. I know I was using some better end Monster 12guage. Not exactly top end wires, but not exactly 18guage zip cord either. It still doesn't explain why I heard an audible difference with an identical setup.

***Edit. Also, if you look, the sigma circuit used it's own speaker wire, it didn't share wires with the outputs.


----------



## thylantyr (Jan 21, 2008)

a$$hole said:


> Didn't you just post this ?
> 
> quote
> Go to the forum and look at it. Every topic is game to analysis, ie I just
> ...


What is your question? Do you want to know the Zuki mystery? If so,
it's all speculation. I sent you the link many days ago to this. Did you 
not get it ?

A very quick summary of events.
1. Zuki amp guts posted.

2. Something interesting was found that is not common in amplifier design
and I had a personal curiosity on what this is.

3. I received a mystery email from someone who wishes to be anonymous,
and tells me that certain Soundstream amplifiers have this because they
have the schematics.

4. This 'fingerprint' item is seen on certain Soundstream amplifiers, then
found on certain Genesis amplifiers and now Zuki.

5. Cool......... I know what this mystery circuit is. The next question is,
why would someone do this? It's not common at all and it doesn't seem like
a good idea to use -- because nobody does it --

What do I know so far?

1. I know that Soundstream amplifiers came before Genesis.

2. I know Nelson Pass designed the first Soundstream amplifiers in the early
80's.

3. I don't see this 'fingerprint' on the Nelson Pass designed Soundstream
amplifiers.

4. I asked Nelson Pass to confirm. He said;

////////////////////////////////////////////////////////////////////////////


> Not without some resistance in series with each diode also -
> we have to avoid current hogging.
> 
> Generally when you put diodes in parallel with emitter/source
> ...


What he is saying is that if you do this scheme, an addition component is
needed and it's used for bias stability at low current. He used this method
35 years ago.

It is implied:

A. He no longer uses this method.
B. At higher current draw, all hell can break loose.  
////////////////////////////////////////////////////////////////////////////

5. If Nelson didn't do this scheme in the Soundstream design, then who did?
We don't know, but we speculated that maybe Wade Stewart did this
scheme as those amplifiers he designed have it.

6. We are also speculating that when Genesis entered the car audio market, they also used this scheme. You can draw your own conclusion on this.

7. Now Zuki has this scheme.

8. We also know Zuki is not technical because I spent hours doing research
on Zuki's cyber posts to understand the individual. He's already claimed that
he is not technical. An assumption is made that Zuki had to have someone
doesnt the product *OR* reverse engineer and existing product and do some
small mods to it.

A. If Zuki hired someone, then this person also used that 'fingerprint' circuit
and this points back to the Soundstream designer because I don't think
Gordon Taylor is going to make a product for Zuki, they deny this. Circuit
designers are a create of habit, if they did something esoteric with circuit
design, they might repeat it. I see this 'repeat' in the Zuki.

B. If someone with some electronics experience reverse engineered a
Soundstream and/or Genesis, they also included that funny circuit, perhaps
unbeknownst to them what it is.

9. Zuki is an audiophile, home and car audio. Because audiophiles are paranoid
about things that make no difference, it makes sense to him to use similar
PCB parts placement methodologies as the Soundstream and Genesis product
because he doesn't want to disturb the 'SQ'.....   

10. A cyber post say that Wade Stewart was influence by Nelson Pass,
so lets run with this idea. Nelson Pass uses this weird method in 1972 and
Wade is a student. Also copies the idea and continues to use it, but Pass
doesn't use it. Later someone else uses the idea probably because they
reverse engineered a Sounstream.

Conspiracy theory


----------



## thylantyr (Jan 21, 2008)

WRX/Z28 said:


> I guess that would work if speaker wire had a constant resistance for every type/guage. I know I was using some better end Monster 12guage. Not exactly top end wires, but not exactly 18guage zip cord either. It still doesn't explain why I heard an audible difference with an identical setup.
> 
> ***Edit. Also, if you look, the sigma circuit used it's own speaker wire, it didn't share wires with the outputs.


Redo the math for whatever wire you used.

You said 12 awg? -> 0.0015 per foot.

Lets assume 2 feet of wire used.

REDO the math for DF = 10,000

The amplifier is now at 0.0004 ohms.

Add the speaker wire [0.003] and the new total is;

0.0004 ohms + 0.003 ohms = 0.0035.

DF is now;

DF = Zload / Zsource

DF = 4 ohms / 0.0035 ohms

DF = 1142

//////////////////////////////////////////////////////////////////////////////////

*These past exercises just show you that speaker wire places a big role.

*DF is also affect by frequency.

*The servo issue is just an esoteric circuit created by some circuit
designer in audio fantasy land because maybe at the time high DF sold
amplifiers because of the perception.

*If you heard a difference between the servo enabled, then one of three
things come to mind.

A. They lied about the DF specs, before and after servo. Manufacturer's lying
about the product ? ... never! ...

B. The circuit design was crap without the servo engaged and hence you
heard something.

C. Jedi mind trick.

If your amplifer+wire combo has a crappy DF, lets say DF = 25 driving
a 4 ohms speaker, you won't notice this because the amplifer output
impedance is about 0.16 ohms. This 0.16 ohms is much less than 4 ohms,
it really doesn't play a role.


----------



## GlasSman (Nov 14, 2006)

thylantyr said:


> 10. A cyber post say that Wade Stewart was influence by Nelson Pass,
> so lets run with this idea. Nelson Pass uses this weird method in 1972 and
> Wade is a student. Also copies the idea and continues to use it, but Pass
> doesn't use it. Later someone else uses the idea probably because they
> ...


Just sounds like the student not following the path of the master..... a bit of reverse engineering......and not enough outside input from "NO BS NON AUDIOPHILE engineers". 

:blush:


----------



## FoxPro5 (Feb 14, 2006)

thylantyr said:


> a$$hole; I don't know what you are talking about. hehe
> I'm not following any guy to see if he made good on promises.


Nobody does. His posts are even more mysterious than Zuki himself. 

I have a question for you Thy:

Bi-polar power supplies....
- are the still used today?
- any benefits over other power supplies?

Sorry, I know nothing about them...or what types of PS even exist, I just _heard_ them spoken about in reference to a well built and well respected amplifier design.

Thanks, and keep up the good ********....I ....mean ....work.


----------



## thylantyr (Jan 21, 2008)

FoxPro5 said:


> Nobody does. His posts are even more mysterious than Zuki himself.
> 
> I have a question for you Thy:
> 
> ...


A battery has two terminals. Plus and Minus.

This is a power supply too.

* two batteries wired in parallel offer the same voltage, double capacity.
* two batteries wired in series offer double voltage, capacity of one battery.













*Two batteries in series to make a bipolar power supply*









By making the center node the ground reference, you now have +1.5 volts
and -1.5 volts. 

If you move the ground reference to the bottom, now you have a +3 volt
and ground battery.

The bioplar power supply is just a fancy name for this scheme. It is used
in *any audio amplifier*, except very low wattage ones.

Also if it's not used, then the amplifier may have a 'H-bridge' output stage 
which doesn't need a bipolar scheme.

This is a full bridge. Replace the motor with a speaker.
One supply, but the transistor requires are not double to do this job.























more here;
http://www.maxim-ic.com/appnotes.cfm/an_pk/3977


----------



## LastResort (Oct 24, 2007)

Interesting stuff, the H bridge is interesting to me as it's the base circuit for PWM VFD's and such. I didn't realize it would be used regularly in the audio field.


----------



## Et Cetera (Jul 28, 2006)

Interesting read so far. A question: Whats the truth in these so called Regulated Power Supplies that promise same output irrespective of input voltage (11~16V in Steg).


----------



## Oliver (Jun 25, 2007)

R.I.P.S.

http://mobile.jlaudio.com/products_amps_pages.php?page_id=46


----------



## thylantyr (Jan 21, 2008)

Et Cetera said:


> Interesting read so far. A question: Whats the truth in these so called Regulated Power Supplies that promise same output irrespective of input voltage (11~16V in Steg).



Technically all power supplies are regulated, even unregulated ones are
really regulated.  That requires more math to lay down and it's boring.

-->The best way to remove the mystery is to have amplifiers tested.

I remember reading an old Richard Clark post where he did test amplifiers
that claimed to offer the same power output even if the DC input voltage
dropped. These amplifiers he tested didn't do what they claimed and
power output also dropped.... is anyone surprised?


----------



## Fixtion (Aug 25, 2006)

car to give an inspection of the following amps.

http://lunaramplifiers.com/news_2.html

all observations are welcomed.

*-fixtion*


----------



## jj_diamond (Oct 3, 2007)

Fixtion said:


> car to give an inspection of the following amps.
> 
> http://lunaramplifiers.com/news_2.html
> 
> ...


besides crappy specs , they don't look appealing IMO.


----------



## Oliver (Jun 25, 2007)

Designed and Manufactured in the U.S.A. 
All Amplifiers are designed and manufactured in Opelousas, Louisiana.  

Big plus, for some !!


----------



## Oliver (Jun 25, 2007)

Contact info:

[email protected]


----------



## kappa546 (Apr 11, 2005)

lunar amps are bad ass.


----------



## thylantyr (Jan 21, 2008)

*http://lunaramplifiers.com/ *




> Patented,Three Surface, Forced Convection Cooling
> System -- Thermostat controlled fan moves cool air around
> the internals of the Amplifier, then forces the air over two
> layers of the heatsink.
> ...









































If the amplifier design is efficient the heatsink issue becomes less important. They say it's a class AB amplifier
therefore this amplifier probably can get hot just like any
other class AB amplifier. Now we can analyze the heatsink
design to see if it makes sense.

Lets use a 'reference' design to compare with.

This is a home audio amplifier, Plinius SA250. There
are three heatsink modules per side. That heatsink 'style'
is one of the best designs, it's great for removing heat and
the vertical orientation makes it great for 'fanless' design.
Large fins, large surface area and the transistors would
mount on it's base. This idea can be considered a golden reference to follow. Anything less can be cnsidered 
crippled.












You are familar with computers and CPU's. One CPU needs
a big azz heatsink to remove the heat. Lots of fins, plus
fan.











Now look at the amplifier chassis design. It looks interesting because it's one slap of aluminum and there the
transistors attach to the solid block. But there is no fins
on the other side.

Normal heatsink.
fins > block > transisor

CPU cooler.
fins > block > CPU

The Lunar design is.
block > CPU

No fins = poor heatsink design.

The amplifier cover is useless as a heatsink.











Red Flag:

Is that paint on the alumimum ? WTF ?


----------



## durwood (Mar 7, 2007)

what's also interesting about the lunar, the longest fins (aka most surface area for cooling) is on the underside of the chassis. Hoes does one remove the heat after you mount it down using the screw holes. LOL. 

I guess it's supposed to float in mid air somehow?


----------



## thylantyr (Jan 21, 2008)

> Salute !............... Made in USA


----------



## durwood (Mar 7, 2007)

thylantyr said:


>


buwahahahahaaa........


----------



## seagrasser (Feb 6, 2007)

It is not a passive cooling design. Output devices are clamped to the thickest part of the aluminum chasis and a fan daws air over the cooling fins fom the bottom to the top where it exhausts.

Designed in the muggy climate of Louisiana. Heat is not a trivial matter. Marketing....well they still need to work on it.


----------



## durwood (Mar 7, 2007)

seagrasser said:


> It is not a passive cooling design. Output devices are clamped to the thickest part of the aluminum chasis and a fan daws air over the cooling fins fom the bottom to the top where it exhausts.
> 
> Designed in the muggy climate of Louisiana. Heat is not a trivial matter. Marketing....well they still need to work on it.


I don't see how it's possible. How does the fan pull air from underneath, when the sides seal up the ends, the circuit board covers the heatsink, and the amp gets bolted down to a flat surface?

It becomes a small space heater for the circuit board from underneath from what I can tell. If you mounted this to carpet, or vinyl it would probably slowly melt it over time. Paint and fiberglass would probably not fair too well either.


----------



## thylantyr (Jan 21, 2008)

seagrasser said:


> It is not a passive cooling design. Output devices are clamped to the thickest part of the aluminum chasis and a fan daws air over the cooling fins fom the bottom to the top where it exhausts.
> 
> Designed in the muggy climate of Louisiana. Heat is not a trivial matter. Marketing....well they still need to work on it.


They are not the only amplifier company guilty of crappy
heatsink design. This is one area where companies cut
corners in the name of cost savings.

I don't want to make it appear that they are getting
special attention, but they do brag about this patented
design that is worthless.   


These ancient amplifiers below have good heatsink design, but
they also fail on transfering heat from the transistor to
the heatsink.























Then you have this ancient design, nice heatsinking, transistors installed properly, but the design as a whole
is overrated.










From these to these;













This is a good example of a modern design well done.




















But wait... the transistor to heating interfacing is a failure. /TRUe
.. Lets mount the transistor, not on the heatsink, but a stupid piece of
angle iron.... That's because they use TO3 metal can transistors that
hinder progress. Concert that design to TO3P*lastic* and it's a better
design. 









Post #40 covered this already.... hehehe Beating the horse so people can be
better designers..........


----------



## t3sn4f2 (Jan 3, 2007)

Is Zed doing pretty much the same thing with regards to the immediate path the heat takes from the transistors? Mounting them on a single fin and letting the heat transfer to the massive part of the heat sink through a smaller total area? Or do the transistor clips only grab on the top side opposite the transistors and then bottom side solid block leading to all the fins?

Edit: "Pretty much" meaning only to the way the transistors clamp on to a ruler of aluminum and the edge of the ruler is all the surface area that transmits the heats to the bulk of the heat sink mass.


----------



## thylantyr (Jan 21, 2008)

////////////////////////////////////////////////////////////
*Analogy*

Zed aka Stephen Mantz is akin to George Lucas. Made some
killer movies in the old days and the lastest creations are a
mixed bag, from a movie critic point of view  

Ask the creators, they will tell you their best work is now.  

I'm just a movie critic who believe that his older designs
are better *OR* ressurrect some old design ideas with 
a twist. Business can interfere with creativity. 

////////////////////////////////////////////////////////////

The new stuff looks like 'cost savings' to me.

Is that a removable lid that looks like a heatsink ?  

http://www.zedaudiocorp.com/Photographs/Gladius-pics.htm


Compare this to his old designs.

Generation X Thor.


















fins... mass ... solid body

... the guts.... What do you see? I see a small PCB, but
oversized heatsink......... If the marketing people looked
inside this amplifier, they have him cut the heatsink/chassis down to size...  










Lets go back further in time. Before Gen X.

Series VIII Thor.




















Question:
Why is the circuit board look about the same but
in Gen X, the chassis is much larger ?

IIRC, he ditched the rail switching design [class G or equivalent] 
and went to a standard design. The rail switching design can run 
cooler so when you move into a non-rail switching design, the 
heatsink needs to be bigger.

I asked him in email many years ago why he ditched 
rail switching.

His reply was to the effect that he's improving his designs.

/whatever.  


If I had to make a Frankenstein Zed amp using old Hifonics,
I'd use the chassis/heatsink from Gen X and bring back the rail
switcher. You can tweak the other smaller issues as needed.


----------



## Fixtion (Aug 25, 2006)

durwood said:


> what's also interesting about the lunar, the longest fins (aka most surface area for cooling) is on the underside of the chassis. Hoes does one remove the heat after you mount it down using the screw holes. LOL.
> 
> I guess it's supposed to float in mid air somehow?


it uses active cooling via top mounted fans which blow air on components and *exit via the bottom heat sink*.

other stated it incorrectly.



jj_diamond said:


> besides crappy specs , they don't look appealing IMO.


all amps are significantly under rated. you'd be suprised what 40x2 lunar watts can push. 



durwood said:


> It becomes a small space heater for the circuit board from underneath from what I can tell. If you mounted this to carpet, or vinyl it would probably slowly melt it over time. Paint and fiberglass would probably not fair too well either.


if youre mounting electronics esp. heats on carpet, or vinyl then you're break the first basic rules of installation of electronic devices. ever read the warning lables when you buy a dvd player, game console, ht receiver?

these amps only reach thermal levels when ran on 2ohm loads over 2-6hours, specifically the L100x2.


thylantyr, minus the fact it's a bad heat sink design, what can you tell us about the placement of components on the board?

*-fixtion*


----------



## thylantyr (Jan 21, 2008)

> it uses active cooling via top mounted fans which blow air on components and exit via the bottom heat sink.


The parts that are a concern in amplifiers are;

1. Power transistors [attached to heatsinks]
2. The transformer

The transformer if designed properly should heat up
to the point where it melts the insulation and/or melts
the solder, but I have seen both when a power supply
is under-designed. For now, we can rule out the power
supply transformer since it's just a hunk of wire, there is
no semiconductors to blow up  

What about the small signal components? The 1/4 watt
resistors, the small signal transistors, capacitors, the
opamps, etc.

These devices don't really product substantial heat that
causes problems. If they did, you'd see individual heatsink
on each component.

Why do car amplifiers have fans on the inside blowing
air on the PCB ?

I've seen a few types of schemes, most are useless.

That TRU design in the previous post at least has some function using two fans to circuit air to keep the transformer cool. 

Adding a fan doesn't hurt, it only really helps keep
the transformer cool, but it does nothing to keep
the power transistor cool. 

One side is metal, one side is not. The metal side needs
to be attached to the heatsink. The heatsink has the job
to keep the transistor cool. Blowing air on the other side
the transistor isn't going to help your situation.









Analogy:

If blowing air on the transistor helps, then who needs
a CPU heatsink, why not just install a fan right on the
CPU ? .... because it doesn't work..........  



> these amps only reach thermal levels when ran on 2ohm loads over 2-6hours, specifically the L100x2.


Questions.

What test method do they use?


Comments.
For sake of argument, lets say a Lunar amplifier does
well on a test bench, it reaches 80 degrees C on the 
transistor and the amplifier operated for hours. /sweet.

Is it sweet because it ran for hours? yes
Is it sweet that it's at 80 degrees C? nope

Sweet would be taking the Lunar design and making
a proper heatsink so it operates at 45 degrees C
and runs for hours. 



> minus the fact it's a bad heat sink design, what
> can you tell us about the placement of components on the
> board?


I will check it tonight, but the pics are not high quality.


----------



## durwood (Mar 7, 2007)

Fixtion said:


> it uses active cooling via top mounted fans which blow air on components and *exit via the bottom heat sink*.
> 
> other stated it incorrectly.
> 
> ...


Still doesn't make any better. Let's think about this logically. Look at it like this. You are the heatsink, sun (transistor) is beating down on you heating you up. Time to get out the fan to cool you off, but wait someone is standing in front of you holding up a sheet of wood right in front of the fan (circuit board). Now I ask you, will you feel the draft created by the fan?



> if youre mounting electronics esp. heats on carpet, or vinyl then you're break the first basic rules of installation of electronic devices. ever read the warning lables when you buy a dvd player, game console, ht receiver?


First, all those have mouting feet for adequete mounting. Does this amp have that built in? No. Second, no home theater receiver EVER has put the heatsink on the bottom. It's just a dumb idea plain and simple. So what do you mount your amps to in the car?




thylantyr said:


> Adding a fan doesn't hurt, it only really helps keep
> the transformer cool, but it does nothing to keep
> the power transistor cool.
> 
> ...


Exactly.


----------



## FoxPro5 (Feb 14, 2006)

What does "IHF dynamic headroom" mean? I saw this on a spec sheet recently and I've never seen it before. It said the amp had an IHF dynamic headroom of 3 dB. Is it another worthless stat?


----------



## Oliver (Jun 25, 2007)

FoxPro5 said:


> What does "IHF dynamic headroom" mean? I saw this on a spec sheet recently and I've never seen it before. It said the amp had an IHF dynamic headroom of 3 dB. Is it another worthless stat?


That spec is listed here

http://nadelectronics.com/products/hifi-amplifiers/C272-Stereo-Power-Amplifier/specs

Nothing new !
A Musically Appropriate Dynamic Headroom Test for Power Amplifiers 
The EIA RS-490 (former IHF A-202) amplifier test standard includes a "dynamic headroom" test employing a 20-mS tone-burst. In an informal survey of musical recordings, power bursts were found with durations from a few milliseconds up to several hundred milliseconds, with an apparent clustering in the 80-200-mS range. Since the practical value of an amplifier depends on its ability to reproduce musical dynamics, a more useful power rating would be obtained by amending the dynamic headroom test to employ a 200-millisecond (or similar) tone-burst. 
Paper Number: 2504 AES Convention: 83 (October 1987) 
Author: Mitchell, Peter W. 
Affiliation: Mystic Valley Audio, Oceanside, CA


----------



## durwood (Mar 7, 2007)

FoxPro5 said:


> What does "IHF dynamic headroom" mean? I saw this on a spec sheet recently and I've never seen it before. It said the amp had an IHF dynamic headroom of 3 dB. Is it another worthless stat?


Simplified version,

Q: RMS of a sinewave is how many dB down from peak power?
A: -3dB 

Basically that's when you hit full rail voltage supplied to the output transitors by the transformer.


----------



## FoxPro5 (Feb 14, 2006)

durwood said:


> Simplified version,
> 
> Q: RMS of a sinewave is how many dB down from peak power?
> A: -3dB
> ...


So in other words, crest factor?  

If you hit the full rail voltage for 100ms intermittently over the course of a hard hour of driving the amp, what does that tell you about the IHF rating?


----------



## durwood (Mar 7, 2007)

FoxPro5 said:


> So in other words, crest factor?
> 
> If you hit the full rail voltage for 100ms intermittently over the course of a hard hour of driving the amp, what does that tell you about the IHF rating?


Take Soundforge, generate a sinewave testone at 0dB amplitude. Then run statistics on it.

What is the "average RMS" value? 

The average RMS is the power rating you see on an amp. 0db peak is when you hit the voltage rail, or what used to be called max power before it was abused.

Sure crest factor.

Let's say your voltage rail is +/-35V.
Average power or (RMS is improper term used) = 35*0.707=24.75V out with a pure tone. On peaks you hit the 35V rail. Although there will be loses from transistors and also power sag could come into play. If your capacitance on the rail is strong enough, then it will have some reserve and not get killed too bad. Disclaimer: Rail capacitance DOES NOT EQUAL input capacitance or "stiffening caps".


----------



## ogahyellow (Apr 16, 2007)

durwood said:


> Let's say your voltage rail is +/-35V.
> Average power or (RMS is improper term used) = 35*0.707=24.75V out with a pure tone. On peaks you hit the 35V rail. Although there will be loses from transistors and also power sag could come into play. If your capacitance on the rail is strong enough, then it will have some reserve and not get killed too bad. Disclaimer: Rail capacitance DOES NOT EQUAL input capacitance or "stiffening caps".


My understanding was that average power and RMS power were different for sinusoidal waveforms. The [mathematical] average power of a sine wave would be 2*Amplitute / pi = 0.6366, for 22.281V. Versus the RMS value you listed above.


----------



## Fixtion (Aug 25, 2006)

thylantyr said:


> Adding a fan doesn't hurt, it only really helps keep
> the transformer cool, but it does nothing to keep
> the power transistor cool.
> 
> ...


air is circulated from the cooler outside the amp to the blistering heat inside the amp. granted it's not a one solution configuration, and i will agree it can be done better. though it's better than nothing. 



thylantyr said:


> Questions.
> 
> What test method do they use?.


i understand the need to set controlled settings, but the thing with car audio is the setting is never controlled.

i'm only concerned with how will the equipment perform given an ever changing car cabin/trunk?

those are my test methods, real world, real music, real use.

not sine wave induced, temperature controlled, increasing voltage, which makes sense for home theater, but place amp testing in context to car audio.

diy*mobileaudio* we respect your knowledge, but respect where you are. :]

i look foward to your inspection of the amp guts.

*-fixtion*


----------



## thylantyr (Jan 21, 2008)

> air is circulated from the cooler outside the amp to the blistering heat inside the amp. granted it's not a one solution configuration, and i will agree it can be done better. though it's better than nothing.


The goal to have exposed heatsink fins. If the fins are
on the inside of the amplifier with a cover, you need a fan.

Compare the two methods, which ones makes more sense.









A lot of amplifers on the markets skimp on heatsinking,
we aren't only picking on this amp.

I don't see anything funny with the rest of the stuff,
maybe they can clean up the marketing babble up a bit
and modernize their website. They say it all started over
a decade ago. They can probably take the amp guts
and streamline their chassis/heatsink design, it seems
to complicated for the function it provides.


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## MiniVanMan (Jun 28, 2005)

Fixtion said:


> i understand the need to set controlled settings, but the thing with car audio is the setting is never controlled.
> 
> i'm only concerned with how will the equipment perform given an ever changing car cabin/trunk?
> 
> ...


In car audio, we're not trying to "control" variables, but rather "handle" them. there's only so much modification we can do to a car before we just have to deal with the variables. So, the "control" has to come from the design, and build phase of the equipment we're using. 

I can't change the volume of my cabin space (minivan). What I can control is buying an amp that puts out a good amount of power to overcome that large cabin volume. I've learned that you're throwing caution to the wind when you go off of manufacturer specs.

So, in the end, it's nice to have accurate data on which to purchase your equipment with. Unfortunately, we're victims of marketers that are just trying to push a product. 

I understand that when equipment gets into the car, everything goes to hell. It's only made worse when you have a piece of equipment that isn't what it's advertised as, or you don't have the whole picture.


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## Oliver (Jun 25, 2007)

MiniVanMan said:


> In car audio, we're not trying to "control" variables, but rather "handle" them. there's only so much modification we can do to a car before we just have to deal with the variables. So, the "control" has to come from the design, and build phase of the equipment we're using.


If it could somehow be designed into the amplifier  "Control" would make the day-to-day existence a lot easier !!


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## sqshoestring (Jun 19, 2007)

Hard to see in the Photos, but are there holes in the bottom sink? Seems logical they might blow cool air in the top where it does not get heated much, then it goes under one end of the board and down the inside sink gathering heat. Then through the holes to under the amp, back down to other end thus over the bottom surface of the amp that is also finned? That is how I would do it, that adds up to a lot of surface area and maybe they do not paint that inside surface.


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## drake78 (May 27, 2007)

That is a adcom amp. I think it a unique and effecient active cooling design. The fan actuallly blows down and the heat sink channels air out both ends.


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## sqshoestring (Jun 19, 2007)

Oops, I meant the Lunar amplifiers. I've seen the audiobahn intake amps, that fan does not do a whole lot IMO. There is a chrome covered insignia that actually looks like it blows out over the sinks above the transistors, so it should help.


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## lacruisin (Apr 29, 2008)

If someone in the Los Angeles area were to host an amp meet I could bring the following:

Milbert BaM-235ab
Tru B2110
Zapco Z600C2-SL
Sinfoni 90.2
Linear Power 1502IQ

and Astron power supply VS-50M.


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