# How to improve amplifier dynamics



## antoniobai

Hi all,

Is there any technical way to improve the dynamics of an A/B class amplifier? Though the electrical and charging system of the car is already optimized.

Can an amplifier be modified, not to maximize its RMS watts, but to improve its transients? How are the technical modifications?

Teach me, masters of electronics...


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## dragonrage

The ideal amplifier does nothing but add gain. Any decent amplifier is going to come reasonably close. Add less than a percent of distortion and some amount of noise that is 90dB or so less than the signal? What exactly do you think you need improved? Are you hearing the 0.1% THD your amp is adding?


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## ChrisB

If you want more dynamics, the easiest modification would be to purchase amplifiers that provide you with more power! The chances are somewhere between slim and none for modifying your existing amplifier to produce double the power provided you keep everything else the same. Also, unless you are doubling your existing power, it is usually pointless to swap out gear if dynamics is what you are looking for.


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## antoniobai

Hi Chris, thanks,

By dynamics, I don´t want to mean power or RMS watts. I want to mean dynamics, what is known as:

- Headroom
- Dynamic Range
- Attack
- etc

I know if I change the internal caps for ones with better ESR (lower), I will get fastest sound. But not in bass, because the capacity of these internal stiffening capacitors, is not enough to deliver all the current needed for a bass hit. 

So, when these capacitors suddenly empty at a transient attack, the amplifier request fast current from the system. 

If I install an external capacitor, with low ESR, i will have this fast current to supply the need of this fast transient once the internal caps can´t keep the voltage high. But once again, a 1F capacitor is not enough to feed a bass hit, so when it empties, again is requested the current needed from the system.

Now is the battery who has to fullfill the fast current for the peak. But regular batteries (even good ones), can't deliver this peak as fast as needed. So, in conclusion, the peak is rounded a bit, and it looses attack... dynamics. 

The point is not the current quantity, but the speed of its delivery. It has to be delivered very fast by the chain, to fullfill the instantaneous peak requierements. If the chain system can´t deliver it that fast, the sound is loud, but not "peaky", not dinamyc. Hence, not faithful to the original recording.

So, my question is. If I install a bigger than 1F capacitor, next to the amplifier, will the sound be more dynamic, as I suspect? If not, *what the dynamic capability of an amplifier depend on?*

(please, don´t confuse dynamics with max power, or RMS watts. By dynamics I mean transient capabilty)


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## antoniobai

dragonrage said:


> The ideal amplifier does nothing but add gain. Any decent amplifier is going to come reasonably close. Add less than a percent of distortion and some amount of noise that is 90dB or so less than the signal? What exactly do you think you need improved? Are you hearing the 0.1% THD your amp is adding?


Hi dragonrage,

Thanks for your input. The 0,1% measured by the manufacturers, correspond to stationary signals. Not to transients. Transient behaviour of an amplifier varies depending on the loudspeaker complex reactance.


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## ChrisB

antoniobai said:


> Hi Chris, thanks,
> 
> By dynamics, I don´t want to mean power or RMS watts. I want to mean dynamics, what is known as:
> 
> - Headroom
> - Dynamic Range
> - Attack
> - etc
> 
> I know if I change the internal caps for ones with better ESR (lower), I will get fastest sound. But not in bass, because the capacity of these internal stiffening capacitors, is not enough to deliver all the current needed for a bass hit.
> 
> So, when these capacitors suddenly empty at a transient attack, the amplifier request fast current from the system.
> 
> If I install an external capacitor, with low ESR, i will have this fast current to supply the need of this fast transient once the internal caps can´t keep the voltage high. But once again, a 1F capacitor is not enough to feed a bass hit, so when it empties, again is requested the current needed from the system.
> 
> Now is the battery who has to fullfill the fast current for the peak. But regular batteries (even good ones), can't deliver this peak as fast as needed. So, in conclusion, the peak is rounded a bit, and it looses attack... dynamics.
> 
> The point is not the current quantity, but the speed of its delivery. It has to be delivered very fast by the chain, to fullfill the instantaneous peak requierements. If the chain system can´t deliver it that fast, the sound is loud, but not "peaky", not dinamyc. Hence, not faithful to the original recording.
> 
> So, my question is. If I install a bigger than 1F capacitor, next to the amplifier, will the sound be more dynamic, as I suspect? If not, *what the dynamic capability of an amplifier depend on?*
> 
> (please, don´t confuse dynamics with max power, or RMS watts. By dynamics I mean transient capabilty)


Ahh, but more RMS power would get you more dynamic headroom and it is easier to upgrade to more power than to try to squeeze the proverbial blood from a turnip. 

Regardless, you can attempt to do whatever you want to modify your amplifier, but you will always be limited by the overall engineering of your product.


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## PPI_GUY

The old Proton amplifiers had fantastic headroom and were super clean. Pretty low power output by todays standards though. 'You might want have a look at how they were built.


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## subwoofery

Got this info from Ray @ Linear Power: 


> We have gone over high voltage and high current designs, and now I will speak about regulated and non-regulated power supply design.
> 
> In a regulated amplifier the power supply is controlled or regulated to work with in a voltage or power window and produce a given amount of power in a very small range. This reduces the peak current draw and averages it into a more continous current draw. The so called marketing advantage to this system is a product that looks more efficient and that will make the virtual same power from say 10 volts to 16 volts. The actual BAD things of this design is that first, if voltage drops, the amplifier has to make up for this voltage loss across the circuit by supplying more current which at very low voltages and over a sustained period of time drives a heavy load on the power supply and the power supply fets which in turn often fail. Secondly, there is no advantage for keeping voltage up and consistant (other than to keep your power supply alive), there basically is no power increase, other than a very small one. Thirdly, a regulated power supply has set a power ceiling as such on the capabilities of the power supply, this reduces overall dynamics and headroom of the amplifier, because there is no extra power to draw from. This is why most amps on the market have 1 dB or less of headroom or reserve power and very little dynamics. They fall on their face when a peak musical note comes along in the music and the amp is already being stressed to produce nearly full power for the normal listening level. They maybe able to respond with a little extra power but no where near the burst power to make a musical peak be reproduced properly.
> 
> A NON-regulated, or unregulated power supply design on the other hand has several advantages. One is that if battery power is held to a normally high level the amplifier can give you more power than it is rated for, if it was rated correctly to begin with. Secondly, if battery power drops the amp will not respond by driving itself with extraordinarily too much current and kill itself, the power just drops back. This gives the amplifier a secondary type of protection from low voltage, it just drops the power back with the drop in battery voltage and does not over current itself.
> 
> It should be your responsibility whether you have a regulated or unregulated power supply designed amplifier to have an adequate electrical system to support the amplifier. In 22 years of repairing all brands of amplifiers (90 pecent being regulated design) this is the second most common failure in amps (over driving or over curent of the power supply), this is only second, next to "too low of speaker impedance", which destroys the outputs then over drives the power supply, since most of these amps are high curent design and cannot utilize over current protection well enough (if at all) to protect the power supply. This is because the over-current protection to protect the power supply from too low of loads, bad speakers, or shorted wiring cannot discriminate closely enough between a short and the "normally" low load of the speaker. Either it is set to protect and falsely trip all the time (custmers *****), or set not to false and provide inadequate or no protection and the amp fails(customers *****). This is another good reason to drive higher impedance loads with high voltage amps, they can have protection that works, and that is not confused by a normal low impedance load or a NON normal bad low impedance load.
> 
> Thirdly, a unregulated power supply design typically has an average current draw less than that of a regulated amplifier which makes it more efficient on average. A unregulated power supply does have more peak instantanious current draw for dynamic musical input, this gives the amplifier the unbridled capability to asking from the battery the power (this peak draw can be 4 times or more the rated fuse size, but only lasts for a few milli-seconds at a time)it needs to try to reproduce a peak muscical note. This in turn gives unregulated amps much more headroom and dynamics than regulated power supply designed amplifiers. This is why all the old Linear Power amps sounded so good and dynamic, they had 3 dB+ of headroom, and plenty of reserve power for dynamics. Other things that go with the unregulated design to make it work well is that the design should be over built. An example of this is that the power supply for the new Linear Power LP2150 is only working at around 15 percent of capability to produce rated power, this gives tremendous reserve power and headroom, and nearly un-believable longivity and reliability.


From my understanding, you need to rebuild your power supply so that it works less than half of it's capability, better transformer for more efficiency, more heatsink to keep all that cool and efficient. Also, in the output stage, you need to have a large power reserve of the output transistors, storage caps near transistors and create a large enough bandwith. Resulting in full power when needed, no compression of the sound due to limited bandwith and low distorsion. 

Therefore, my advice is the same as ChrisB, just buy another amp that has more RMS so that you're using less than half it's capabilities. 

Kelvin


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## IBcivic

ChrisB said:


> Regardless, you can attempt to do whatever you want to modify your amplifier, but you will always be limited by the overall engineering of your product.


Like trying to turn a Fiat 500 into a Lamborghini


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## antoniobai

Haha, guys, I appreciatte your sense of humour... 

But seriously, does anybody know exactly, specific and technically, what depends on the dinamic capability of an amplifier?


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## subwoofery

antoniobai said:


> Haha, guys, I appreciatte your sense of humour...
> 
> But seriously, does anybody know exactly, specific and technically, what depends on the dinamic capability of an amplifier?


Well, I explained it in my previous post... You need to have a much stronger power supply, upgrade your output stage and have more heatsink. That's it, easy . 

Kelvin


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## Brian_smith06

What are you running currently?


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## antoniobai

subwoofery said:


> Well, I explained it in my previous post... You need to have a much stronger power supply, upgrade your output stage and have more heatsink. That's it, easy .
> 
> Kelvin


Please, specify a bit more. You mean to make a bigger power supply (Toroid, filtering caps, etc), then to upgrade the output stage (better stiffening capacitors? Bigger ones??... bigger transistors??? faster ones???), and more heatsink...

OK, it sounds as you suggest getting more power, and getting the amplifier bigger... But it sounds strange, because you can make small amplifiers with great dynamics. Something could be wrong in this exposition... 

My question would be then: if small amplifiers can give great dynamics, why don´t all manufacturers make great dynamics amplifiers? If it is that easy, and all of them know how to do it, they could do it in the same or similar package...

But not... you have similar size HiEnd amplifiers, and some of them have noticeabily better dynamics than the others. I mean for example, Steg K2/02, Genesis Dual Mono, Rockford T600-2. They both are similar size, similar watts, etc... The Rockford is even a bit smaller. But their dynamics are much better than the Dual Mono, for example.

How is it done? Where is the technical hint to the dynamics?


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## subwoofery

antoniobai said:


> Please, specify a bit more. You mean to make a bigger power supply (Toroid, filtering caps, etc), then to upgrade the output stage (better stiffening capacitors? Bigger ones??... bigger transistors??? faster ones???), and more heatsink...
> 
> OK, it sounds as you suggest getting more power, and getting the amplifier bigger... But it sounds strange, because you can make small amplifiers with great dynamics. Something could be wrong in this exposition...
> 
> My question would be then: if small amplifiers can give great dynamics, why don´t all manufacturers make great dynamics amplifiers? If it is that easy, and all of them know how to do it, they could do it in the same or similar package...
> 
> But not... you have similar size HiEnd amplifiers, and some of them have noticeabily better dynamics than the others. I mean for example, Steg K2/02, Genesis Dual Mono, Rockford T600-2. They both are similar size, similar watts, etc... The Rockford is even a bit smaller. But their dynamics are much better than the Dual Mono, for example.
> 
> How is it done? Where is the technical hint to the dynamics?


I don't know enough about amp building to detail the specifics. Sorry. 
Maybe someone else can chime in or try to contact amp manufacturers (but I don't think they will give up their secret recipe )

Small amps can be made to have more dynamics but the power output will be much less than that of a comparable sized amp. Why less power output? If you don't limit the output, the temperature will rise too much from the power supply working much harder - meaning you need more heatsink or a cooling fan. 

Kelvin 

PS: The RF doesn't have more dynamics, it's just that their freq response is not as flat (slight bump in midbass) as others and they underate their amp - you get "perceived" dynamics.


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## antoniobai

subwoofery said:


> I don't know enough about amp building to detail the specifics. Sorry.
> Maybe someone else can chime in or try to contact amp manufacturers (but I don't think they will give up their secret recipe )
> 
> Small amps can be made to have more dynamics but the power output will be much less than that of a comparable sized amp. Why less power output? If you don't limit the output, the temperature will rise too much from the power supply working much harder - meaning you need more heatsink or a cooling fan.
> 
> Kelvin
> 
> PS: *The RF doesn't have more dynamics, it's just that their freq response is not as flat (slight bump in midbass) as others and they underate their amp - you get "perceived" dynamics*.


I agree with you at everything, except with the last statement in bold. The Rockford DO give faster and cleaner dynamics. I have owned all of these amplifiers enumerated above. Its frequency response has 1 dB bias at 200 Hz and 2 KHz. But nothing to do with dynamics... The T600-2 is much more cleaner and faster driving dynaudio woofers, believe it. 

Forgot Rockford´s trick is just cheating you with some bumps in frequency... We all could do that... They seem to really care about dynamics. The result is its fame, clean transients with difficult woofers and subwoofers. Clean nd controlled sound. Better than the Genesis or Steg K I owned before, with several different woofers and subwoofers. 

This Rockford and other brands must do something different. 

How about old Orion HCCA2100?? They were beasts also at moving hard drivers. They move dynaudio drivers as fast as they were paper OEM cones. Why? Is it becasue they were high current? I don´t think so... A regular loudspeaker never asks more current than the Ohm´s law obbeys. I think the hint is in the speed of the current delivered...


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## subwoofery

antoniobai said:


> I agree with you at everything, except with the last statement in bold. The Rockford DO give faster and cleaner dynamics. I have owned all of these amplifiers enumerated above. Its frequency response has 1 dB bias at 200 Hz and 2 KHz. But nothing to do with dynamics... The T600-2 is much more cleaner and faster driving dynaudio woofers, believe it.
> 
> Forgot Rockford´s trick is just cheating you with some bumps in frequency... We all could do that... They seem to really care about dynamics. The result is its fame, clean transients with difficult woofers and subwoofers. Clean nd controlled sound. Better than the Genesis or Steg K I owned before, with several different woofers and subwoofers.
> 
> This Rockford and other brands must do something different.
> 
> How about old Orion HCCA2100?? They were beasts also at moving hard drivers. They move dynaudio drivers as fast as they were paper OEM cones. Why? Is it becasue they were high current? I don´t think so... A regular loudspeaker never asks more current than the Ohm´s law obbeys. I think the hint is in the speed of the current delivered...


Reading on the T600-2 test on Car Audio and Electronics Magazine, the boost is more like 3dB ; which can be perceived as dynamics. 
From the reviewer: "This amp is specifically and intentionally designed NOT to have a flat frequency response, even with the Punch EQ turned to a minimum." 

I have not opened one up and don't know how strong the power supply and output stages are. I've heard that amp also and don't find it too bad. 

However, it's not the cleanest amp out there. Distorsion figures @ 4 ohm for the T600 is 1.3% and for the K2/03, it's 0.036% @ 4 ohm. Distorsion is also perceived as increased loudness. Just sayin' 

Kelvin


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## antoniobai

Hi Kelvin,

Please, listen by yourself. These kind of tests were never definitive to chose amplifiers. These parameters are not definitive. You will know it when you listen and test by yourself.

Yes, it can have a boost when you set the Eqpunch to 0. (It actually is not set to 0 internally). But forget it, it is not the dynamics. A dumb can perceive it as dynamics? i don´t know, but neither you, me, or whoever who loves audio, doesn´t perceive a bump as dynamics. 

This amplifier is pretty clean and analitic. But its best is at midbass and bass. It is the cleanest of these 3 amplifiers at this frequency range. It moves dynaudio woofers, or subwoofers, in a more controlled manner (acceleration and braking), the sound is alive and detailed at midbass and bass. All peaks are separated, fast and natural, so more faithful to the original recording, to the recorded dynamic range. This is cleanliness and dynamics. 

If you are interested on its guts, look:










But honestly, I don´t know technically what makes this amplifier stronger moving hard woofers.


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## alm001

Needs more "buzzwords"

Send it to me, I have a modification where I add Headroom, Dynamics, Sparkle, Warmth, Attack, SQ _and_ Imaging.

$1,100 per amplifier is the standard fee, but if you have more than one amp done we can work out a deal.
Special bonus this month is free upgrade to >∞ damping factor.


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## subwoofery

cajunner said:


> it's the Rockford Punch EQ circuit...
> 
> but seriously, Rockford puts out more power than rated. That's it. MORE POWER.
> 
> and, it is clean power because of the proprietary circuitry.
> 
> 
> and, when you say "hard woofers" I assume you mean speakers that have low impedances, and low efficiency.
> 
> Rockford expects people to run their amps at low impedance, so they raise the power envelope to include good performance at these lower impedances.
> 
> the evidence is in the PowerCube, a 3-D representation of power delivered at different ohm levels.
> 
> this is what Rockford is known for.


Thanks... I didn't know what else to say lol 

Kelvin


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## antoniobai

No, what I mean by hard woofers is woofers with high inertial movement (high mass). These kind of woofers, where electrical damping is dominant, require very fast current peaks to change the direction of the woofer, because their capacitive behaviour a bit above the Fs is dominant. Not a lot of amps, but very fast delivery.

Cajunner, you demonstrate you don´t know what you say about this. RMS Power is not dynamics. 

The power cube is a good test to see if the amplifier can drive reactive loads. But it doesn´t measure specifically the max speed of the current delivered. Please, take a look at PowerCube theory.

So, in conclusion, none of us knows the technical explanation of what makes an amplifier more dynamic than other...


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## thehatedguy

Dynamics can come from a lot of "headroom" in the powersupply. More, larger caps can decrease the ESR and add more reserves to prevent sagging rail voltages.

Also in the same regards, increasing the power from the amplifier will do the samething.

Some amp designers like to say their amps have so and so amount of headroom built into them. This is essentially the same as rating an amp at 125 wpc that has the ability to do 250 wpc.


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## mitchyz250f

Hate to get in the middle of this dog fight especially when I don't understand this stuff. BUT, I was speaking to an electrical engineer and he said slew rate was an important factor in dynamics. 

I will hang up now and listen to the responses.


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## narvarr

mitchyz250f said:


> Hate to get in the middle of this dog fight especially when I don't understand this stuff. BUT, I was speaking to an electrical engineer and he said slew rate was an important factor in dynamics.
> 
> I will hang up now and listen to the responses.



I have read the same thing in an artical in CA&E about slew rate being one of the determining factors along with a high damping factor at higher frequencies.

Sent from my X10i using Tapatalk


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## subwoofery

narvarr said:


> I have read the same thing in an artical in CA&E about slew rate being one of the determining factors along with a high damping factor at higher frequencies.
> 
> Sent from my X10i using Tapatalk


Used to be like you thinking that a high damping factor was necessary for an amp to control a driver. Well not anymore, the driver is controlling itself - reactance and energy storage of the driver is what I meant. 

Kelvin


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## narvarr

subwoofery said:


> Used to be like you thinking that a high damping factor was necessary for an amp to control a driver. Well not anymore, the driver is controlling itself - reactance and energy storage of the driver is what I meant.
> 
> Kelvin


Are you refering to the inductance of the driver or a combination of factors?

Sent from my X10i using Tapatalk


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## subwoofery

narvarr said:


> Are you refering to the inductance of the driver or a combination of factors?
> 
> Sent from my X10i using Tapatalk


Please read this: 
http://www.diymobileaudio.com/forum/449977-post34.html 

Kelvin


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## narvarr

subwoofery said:


> Please read this:
> http://www.diymobileaudio.com/forum/449977-post34.html
> 
> Kelvin



Great read. So is that where the debate between High Voltage and High Current came from?

Sent from my X10i using Tapatalk


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## chrisb33

guys ive been reading this thread and i am the first to admit that im a dumb dumb when it comes to electronics and stuff. 

what would the effect if i change the power and input capacitors to "mundorf?" lets say those mcaps or mcap supreme? 

im running full active so i dont need to change those capacitors at the amps crossover. 

thanks.

chris b


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## rayheatfan

Yes I heard the same thing about slew rate being a major factor


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## antoniobai

chrisb33 said:


> guys ive been reading this thread and i am the first to admit that im a dumb dumb when it comes to electronics and stuff.
> 
> what would the effect if i change the power and input capacitors to "mundorf?" lets say those mcaps or mcap supreme?
> 
> im running full active so i dont need to change those capacitors at the amps crossover.
> 
> thanks.
> 
> chris b


Very interesting question! It would be nice if it is answered by an advanced technician or expert.


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## envisionelec

"Attack" "Fast" "High Speed"

These are attributes of a high power system.

You can attribute them to efficient speakers or high current power supplies. As ChrisB said, you can't make a design something it is not. If you succeed in modifying your amplifier to achieve measurably better results, you'll have built another amplifier. A regulated design can suck just as much as an unregulated if the current capacity isn't there. 

"Sparkle" "Smooth"

These are attributes of human opinion. Measures flat; is flat. A lot of amplifier have "sparkle" because their preamps are clipping or their output inductors saturate (Class D). 

Capacitors alone will not get you to sonic nirvana. There are systemic problems that some designs can never overcome.


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## subwoofery

envisionelec said:


> "Attack" "Fast" "High Speed"
> 
> These are attributes of a high power system.
> 
> You can attribute them to efficient speakers or high current power supplies. As ChrisB said, you can't make a design something it is not. If you succeed in modifying your amplifier to achieve measurably better results, you'll have built another amplifier. A regulated design can suck just as much as an regulated if the current capacity isn't there.
> 
> "Sparkle" "Smooth"
> 
> These are attributes of human opinion. Measures flat; is flat. A lot of amplifier have "sparkle" because their preamps are clipping or their output inductors saturate (Class D).
> 
> Capacitors alone will not get you to sonic nirvana. There are systemic problems that some designs can never overcome.


Do you have examples of high-current amps built nowadays? 

Thanks for the great explanation, 
Kelvin


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## envisionelec

subwoofery said:


> Do you have examples of high-current amps built nowadays?
> 
> Thanks for the great explanation,
> Kelvin


Yeah - mine.

All kidding aside, I'm too deep in my work to really pay attention to what's currently (pun *not* intended!) a high current design. I have worked on some nice home audio equipment by Harman Kardon that utilized a separate transformer winding and six output devices per channel. Each channel had its own rectifier, filter caps, etc. 

I've seen more than a few car amplifiers with arrangements like this, but sadly, they're almost exclusively multi-kW Class-D subwoofer amplifiers. 

A "high current" design generally means it was built with a wide error/misuse tolerance. Such a design will produce 100W into a 4 ohm load. The current requirement for this is 5 Amperes, RMS. Peak current is 7.07A (purely resistive load). 

Resistive loads are highest in working current, but reactive loads are hardest to drive because a portion (sometimes significant) is driven back into the output devices and converted to useless heat, activating protection circuits or cause "rail sticking" due to the Miller effects on the driving transistors. A real speaker load can appear as a low impedance under certain (and varying) operating conditions due to its reactive components. Note that the actual impedance doesn't drop below DCR, but _the amplifier_ thinks the load has suddenly become much heavier and usually responds negatively - even if the resistive measurement says "I'm not clipping!". 

Ok, back to the 100W amplifier. At 2 ohms, the current requirement is 10A (14A peak). If the design has enough output transistors, it will be able to _almost_ double its power. The reason it naturally doesn't is related to a property called beta droop which happens when a transistor is pushed to the upper SOA limits (look it up). This means the output can't fully amplify the current so it doesn't. Adding more transistors fixes this, but at the expense of requiring larger driver transistors to support the current gobbled up through the B-E junction (1.4A for 28V, 2 ohms and a beta of 20 / number of transistors). Four transistors per output means that the drivers must deliver 700mA of current!
And if those are big, they're also probably slow. So you use several of those in parallel...more parts - and each needs to be current balanced. It's expensive to do it right!!

There are many distortion mechanisms in _car amplifiers_ that are not uncovered by a resistive load bank. I don't have time to go into all of them, but if your amplifier hasn't been tested into real world, reactive loads - the results are anyone's guess.

Rockford Fosgate has used a tool called the "Power Cube" for years. It can perform voltage/current measurements on the amplifier's outputs through all of the relevant phase angles and display the results in a printout that resembles a 3D stack of blocks. The squarer the blocks, the more linear the current delivery. I've never seen one, but I'd bet it's large. Anyway, they have shown that their amplifiers can deliver rated current and not activate protection circuits. They use FET outputs which are immune to rail sticking. And they have consistently used tertiary windings and discrete regulators on their preamp circuits, making for an overall excellent amplifier. It's when they started messing with a good thing that they....I digress. 

Of course, this kind of engineering costs more money. The shift to place the cash burden on the poor consumer by building amplifiers that run _right at the edge of their stability_ is downright greedy. But they sell lots of them to kids and dealers and enthusiasts alike that don't know any better. Here's my rule of thumb for conventional (A/B with Bipolar outputs): If your amplifier guts contain two output devices per channel and it's rated for anything more than 35W into 2 ohms, close it back up and return it. 

Hope that helps.


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## subwoofery

Interesting... I'm still a noob when it comes to amp topology and technology but that was a great read. 

Thank you, 
Kelvin


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## envisionelec

subwoofery said:


> Interesting... I'm still a noob when it comes to amp topology and technology but that was a great read.
> 
> Thank you,
> Kelvin


 Thank you.  I really enjoy helping people understand the whatzits of car amplifiers. There's a lot of theory that just doesn't translate really well to the regular guy trying to buy the best amplifier he can afford. Not everyone can afford a "correct" amplifier - but what gets me are the people that argue fine details over two differently branded, yet similarly designed amplifiers. 

Rockford used to publish their testing of various amplifiers they brought into the lab. It was revealing - and boy, did it anger a lot of manufacturers. I'll have to find that...

EDIT: Ok, It was in their dealer-only training manual. I don't see it online... But it was cool! You had to be there.


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## ChrisB

Technically, anyone with access to the Audio Precision Reactive Cube can perform this power test.  I was told by an engineer who manufactures amplifiers himself not to put certain brands of amplifier on the audio precision. He said not only would I be disappointed by the power they output, but the THD+N of those boneriffic, SQ amplifiers would be higher than other similarly priced amplifiers on the market. Granted, I believe his implementation of the active global feedback network for enhanced cone control by it's nature causes a higher than normal THD+N number, but, his product will make the power!


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## Aaron'z 2.5RS/WRX

best way to increase dynamics without mods is decrease gain.. 

so maybe work the problem from a different end..?

just thoughts...


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## envisionelec

ChrisB said:


> Technically, anyone with access to the Audio Precision Reactive Cube can perform this power test.  I was told by an engineer who manufactures amplifiers himself not to put certain brands of amplifier on the audio precision. He said not only would I be disappointed by the power they output, but the THD+N of those boneriffic, SQ amplifiers would be higher than other similarly priced amplifiers on the market. Granted, I believe his implementation of the active global feedback network for enhanced cone control by it's nature causes a higher than normal THD+N number, but, his product will make the power!


I've never heard of the AP Reactive Cube. The only device I've ever seen is the Audiograph Power Cube. Tell me more. 

After bringing up the point, I modeled up some ideas for building a PowerCube. Turns out, it's not that hard! Well, if you don't count winding the enormous air core inductors and writing a LabVIEW VI or three... The rest is all polypropylene caps and relays. The only issue is that you have to choose a singular frequency, or build tapped inductors and multiply the caps...and relay contacts. Like I said...it could get huge. 

My test rig has -140dB S/N and 0.005% THD, varies <0.05dB from 10-22kHz and can handle 1200W at 2 ohms, 600 at 4 and 600 at 8. I used to have double that, but I lost the other resistors somewhere along the line. It's not an AP - but it didn't cost anywhere near that. :heart:

Yeah, the car audio world is full of high THD designs. Ever notice how they're always rated at 0.05%THD? 

I recently worked on a Massive (that was the brand name) 4x100W amplifier. It was pretty, but all four channels were drastically underbiased at 0.3V BE. Crossover distortion at 1W was among the worst I'd ever seen. I did a little research on the brand only to be horrified that it is a beloved "old school" design!! Oh, the humanity!


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## TrickyRicky

I agree with those that stated more RMS wattage and turn the gain down. This is one of the best way to have more headroom, dynamics, better THD and SN levels. Its always easy (best) to turn down the gain rather than turning it up. Just think of it as running the amp at 50% and you always have that other 50% stored for that bass note or whenever needed.

Thats why I dont understand why some want a 90% or higher efficient amp. Then you dont have any head room left and dynamics suck.


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## ChrisB

envisionelec said:


> I've never heard of the AP Reactive Cube. The only device I've ever seen is the Audiograph Power Cube. Tell me more.
> 
> After bringing up the point, I modeled up some ideas for building a PowerCube. Turns out, it's not that hard! Well, if you don't count winding the enormous air core inductors and writing a LabVIEW VI or three... The rest is all polypropylene caps and relays. The only issue is that you have to choose a singular frequency, or build tapped inductors and multiply the caps...and relay contacts. Like I said...it could get huge.
> 
> My test rig has -140dB S/N and 0.005% THD, varies <0.05dB from 10-22kHz and can handle 1200W at 2 ohms, 600 at 4 and 600 at 8. I used to have double that, but I lost the other resistors somewhere along the line. It's not an AP - but it didn't cost anywhere near that. :heart:
> 
> Yeah, the car audio world is full of high THD designs. Ever notice how they're always rated at 0.05%THD?
> 
> I recently worked on a Massive (that was the brand name) 4x100W amplifier. It was pretty, but all four channels were drastically underbiased at 0.3V BE. Crossover distortion at 1W was among the worst I'd ever seen. I did a little research on the brand only to be horrified that it is a beloved "old school" design!! Oh, the humanity!


I was told that the reactive load box would reveal all: AP High Performance Audio Analyzer & Audio Test Instruments : Service & Support


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## SoulFly

TrickyRicky said:


> Thats why I dont understand why some want a 90% or higher efficient amp. Then you dont have any head room left and dynamics suck.


1. Most mass consumers use compressed MP3's...If you start with suck, you end with suck.
2. People perceive sound differently and some don't care about dynamics.
3. People have different preferences of sound.
4. Most mass consumers will not invest in a HO Alt. Most can't even use some sound deadening and don't care if they rattle like a tin can.

I suppose if you make an amp and 90% of your customers want high efficiency and small size, taking into consideration there are dozens of amp makers in competition with you then guess what kind of amp you'll be making.

Its a trend, one that can change at any time. Like how car size purchase trends follow gas prices. Smaller cars must mean smaller amps i guess.
That's why you do like most companies and own many brands....like how DirectAudio owns PPI,orion, concept, dei..etc and SoundAround owns Legacy, lanzar, pyle, pyle pro, and pryramid

That way, you can saturate the market and fill everyones needs without as much worry for brand bias. there are many great amps in the market each year but not all of them sell very well each year either.


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## fish

envisionelec said:


> Rockford used to publish their testing of various amplifiers they brought into the lab. It was revealing - and boy, did it anger a lot of manufacturers.



Can you remember any amps that were tested that had "disappointing" results off the top of your head?


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## Mike_Dee

I have a couple old school LP amps in my system, that have _unregulated_ power supplies, and I have a 1 farad cap on the B+ line of my power distro block. It reinforces my voltage drop.


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## TrickyRicky

Mike_Dee said:


> I have a couple old school LP amps in my system, that have _unregulated_ power supplies, and I have a 1 farad cap on the B+ line of my power distro block. It reinforces my voltage drop.


I think you need more than just a cap on the B+ line. More like a hi output alt and maybe an extra battery or two. But it also depends on what amp you got and what music and loudness you like/preffer.

One thing audiophiles know, is constant current and voltage. The smallest drop in either will mess with the dynamics. I remember seeing a youtube video about audiophiles in europe that spend over 100K on their home systems and the most important thing they mention was the whole constant current and voltage problem.


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## envisionelec

ChrisB said:


> I was told that the reactive load box would reveal all: AP High Performance Audio Analyzer & Audio Test Instruments : Service & Support


Chris, the box that Audio Precision is referencing is, indeed, the PowerCube. We're saying the same thing.


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## envisionelec

fish said:


> Can you remember any amps that were tested that had "disappointing" results off the top of your head?


Fish, I'm sure there were - but this was over 15 years ago. I want to say that most Japanese amplifiers were quite overrated. Alpine, Pioneer and Sony for the most part basically lied about their output power and were very unstable into highly reactive loads. I do remember that Phoenix Gold's MPS and MPA series were excellent performers. I think I chose to remember those because they were brands that my shop carried.


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