# Help Me Build an Amplifier.



## Patrick Bateman (Sep 11, 2006)

I've been running Tripath amps for the most part for about fourteen years now. For the most part, I've switched over to amp kits that look like this:










To run these, you basically go on eBay and get yourself a 120V to 24V power supply. I'm using these :

AC 100V 240V to DC 24V 5A Switching Power Supply Adapter for LED Strip Light | eBay

Put the amp with the power supply, and you got yourself four channels of digital goodness for less than $70.

OK, here's the problem:

I want to do this in a car.

I'm pretty sure that I can take the same amp board, and power it with a DC-to-DC power supply. I am looking at a 12v to 24V unit with 10amps:










*Is that all there is to it?* I'm not remotely good at electronics, so maybe I'm missing something? Or is it as simple as putting an amp board with a power supply? (I guess I'll need a power switch too.)




BTW, in case this is a totally dopey question, I did search the forums. It seems like this is a way to get something comparable to a four channel Alpine, but at 40% of the cost.


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## MetricMuscle (Sep 16, 2013)

Andy has mentioned using 20watt IC amps, something like 24 channels worth in his Volvo build some years ago.

What kind of wattage are you looking for?

There are quite a few of this type floating around eBay but I have no idea what they sound like or if in the long run they will end up being more expensive to integrate considering power supply, crossovers and RCA connections etc.

LM1875 NE5532 Audio Power Amplifier Amp Assembled Board G008 | eBay

2 1CH LM1875 25WX2 50W Audio Power Amplifier Amp Board Kit New | eBay


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## Patrick Bateman (Sep 11, 2006)

MetricMuscle said:


> Andy has mentioned using 20watt IC amps, something like 24 channels worth in his Volvo build some years ago.
> 
> What kind of wattage are you looking for?
> 
> ...


It's one of those things where I'm not entirely sure why more people don't do this.









For instance, a few years back I saw that someone had built one of the Nelson Pass amplifiers using a heatsink from a personal computer, and two laptop power supplies.

These items are so cheap they're practically free on eBay; you can get those three items for under $20 easily.

But using those items in lieu of a conventional power supply and heat sink cut the cost of the Pass amplifier down by about $600!

The thing is, I don't know enough about amplifiers or power supplies to know if there's anything inherently wrong with this approach. I'd feel pretty silly if I did something wrong and set my car on fire or electrocuted myself. I'm not terribly concerned with the sound quality of SMPS, because I'm already using them in my home setup and I can't discern any audible difference when compared to a plain ol' AB amplifier. If anything, the AB amplifier sounds worse. (No I didn't do an blind comparison and I don't want to get into a discussion of amplifier sonics lol )


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## thehatedguy (May 4, 2007)

That Pass amp is/was probably the Amp Camp Amp kit...it's good for about 2 watts class A.

12V DC Switching Power Supply - 500 Watt - Car Audio - Power Supplies

That way you have remote turn on soft start, short circuit protection, over and under voltage...the +/-50 volt rails will be plenty of juice.

Plus they have a lot of different amp boards to use it with...and a really good reputation.


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## TallTexan (Dec 14, 2007)

I've had a similar idea for a while as well. I thought about using a broken amp's power supply to get me the power for chip amps. Another aspect of DIY amps is you can also separate the power supply from the amp section and even separate the amp boards themselves. This would help with both cooling and space requirements.

Think about how big and how many components are required for a switched mode power supply. Usually 2 to 4 switching MOSFETs per rail plus rectifiers and caps to get it back to DC. And don't forget the toroidal. Most amp guts, the power supply takes roughly half of the real estate. I'd guess that the p.s. also cost more than half the cost of the amp itself.

The 12v to 24v isn't going to buy much in the way of increased power. Most amp power supplies also have plus, minus, and ground rails. My Mc400 has +- 27v in order to put out 50W/channel and +- 37v for its 100W channels (all at 4 ohm).

I've also looked at some of the other cheap ebay DC-DC and if you read the specs carefully, they don't put out the current you want at higher voltages without some additional cooling. The automotive environment is fairly harsh and I would not want something running at or near max capacity.

Amps are pretty cheap these days and I don't think its worth fooling around with building a DIY one. Sourcing most of the components for DIY is easy enough, but things like toroidal transformers with the proper windings are not off the shelf. Plus there is heat sinking required which I've found heat sinks cost more than the device I'm heat sinking.

Slightly off subject, because DSP have gotten so cheap and are easy to set up crossovers with, I'd love to see amps with no additional, unneeded circuitry. Like the Linear Power amps were.


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## Patrick Bateman (Sep 11, 2006)

TallTexan said:


> I've had a similar idea for a while as well. I thought about using a broken amp's power supply to get me the power for chip amps. Another aspect of DIY amps is you can also separate the power supply from the amp section and even separate the amp boards themselves. This would help with both cooling and space requirements.
> 
> Think about how big and how many components are required for a switched mode power supply. Usually 2 to 4 switching MOSFETs per rail plus rectifiers and caps to get it back to DC. And don't forget the toroidal. Most amp guts, the power supply takes roughly half of the real estate. I'd guess that the p.s. also cost more than half the cost of the amp itself.
> 
> ...











THis is the amp. It's the same one PE sells for $50.

Right now I'm running the amp board with a laptop power supply that provides 24V at five amps.

Again, I'm totally dumb about this, but I don't know if the amp "expects" a positive 24V rail and a negative 24V rail, or a positive 24V rail and a ground.

In fact, I'm not entirely sure if a car has a negative rail. Isn't it +12V and ground?

(Again, I'm dumb as **** when it comes to electronics.)

Here's the web site : Sure Electronics' webstore 4 x 100 Watt 4 Ohm Class D Audio Amplifier Board - TK2050

I'm kinda hoping this does the job, but it's not 100% clear to me if it has a positive and a negative output, a positive and a ground, or what the amp is expecting.

I *do* know it works with my laptop power supply!

I'm tempted to take it out in the car and see if it will power up with 12V. I know that it won't deliver full output with 12V, but at least I could confirm if it needs +12V and ground or +12V and -12V.

Also, if everything I said sounds uninformed it's because I am.


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## TallTexan (Dec 14, 2007)

Patrick: I was using the LM3886 based boards, so called gain clones, class AB boards most of which require what's called a split mode power supply having a positive, negative, and ground. But, according to the datasheet they can be run in single mode.

Obviously, your Sure class D takes a single ended power supply and your laptop power supply would be sufficient. I'm planning a similar setup for my bedroom using a small inexpensive class D board and a couple of reworked Minimus 7s (4" two way die cast aluminum goodness with new drivers/crossover) due to space requirements as well as a laptop power supply.

I'd grab a cheap Harbor Freight multimeter and see what kind of current draw that unit takes when driven. That 12-24v DC-DC converter might work if not driven too hard and kept in an area that is vented/cooled. Your an experimenter Patrick, give it a try, just don't let out the "magic smoke".

I wish I had the seemingly innate audio knowledge you have Patrick to go along with the electronics (and computer) knowledge I have. But that what I like about these forums is a chance to learn from each other. Its been fun watching your experiments with 3D printed speakers and other projects. 

I'm still working on putting two speakers near my head for the "Crazy Wide Soundstage", but currently waiting on the Kravchenko tweeter to finish up (almost a year long wait, half of it on stupid grills).


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## Elgrosso (Jun 15, 2013)

TallTexan said:


> (...)
> Slightly off subject, because DSP have gotten so cheap and are easy to set up crossovers with, I'd love to see amps with no additional, unneeded circuitry. Like the Linear Power amps were.


Something like these









Or even these?


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## Patrick Bateman (Sep 11, 2006)

TallTexan said:


> Patrick: I was using the LM3886 based boards, so called gain clones, class AB boards most of which require what's called a split mode power supply having a positive, negative, and ground. But, according to the datasheet they can be run in single mode.
> 
> Obviously, your Sure class D takes a single ended power supply and your laptop power supply would be sufficient. I'm planning a similar setup for my bedroom using a small inexpensive class D board and a couple of reworked Minimus 7s (4" two way die cast aluminum goodness with new drivers/crossover) due to space requirements as well as a laptop power supply.
> 
> ...


If you need something printed let me know! Filament is so cheap it's basically free. Designing things in 3D takes a while though. The bandpass boxes for my Mazda took about three attempts, each one requiring about 6-8 hours.


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## oabeieo (Feb 22, 2015)

Patrick Bateman said:


> I've been running Tripath amps for the most part for about fourteen years now. For the most part, I've switched over to amp kits that look like this:
> 
> 
> 
> ...


That's the exact supply 24v I'm using to power my tube pre amp , it has zero noise and works great!!! FYI


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## TallTexan (Dec 14, 2007)

Patrick Bateman said:


> If you need something printed let me know! Filament is so cheap it's basically free. Designing things in 3D takes a while though. The bandpass boxes for my Mazda took about three attempts, each one requiring about 6-8 hours.


Patrick:

Thanks for the offer. I've got a co worker who has one of the Rip Rap clones. I'd like to build one myself and include capacity for subtractive process: i.e. allow conversion to use router in place of extruder. Too many other half done projects, like the crazy wide soundstage one.

The speakers I did for the headrest area were made from florist foam for the Vifa TC6 2" mid ($5 PE special) in an egg shape covered a shell made from a thin layer of JB weld epoxy over the shaped foam. I'll make a thread/post about when I'm done.

Elgrosso:

Thanks pretty close to what I'm thinking, but those are mono blocks and I wonder how efficient it is for each channel to have its own power supply.

I'd like to see a setup where a configurable power supply that could either provide let's say a 4 * 150W class D amp module, or 2 * 300W, or 1 * 750W one. Each module roughly the same form factor plugging into the power supply "back plane" which could be separated from the modules via plugs and extension cabling. Separated, each half would fit under most car seats no more than 6" squares each. 

There are already some micro class D amps that have power supply/amp in one small package. PPI A900.1 300W/4ohm mono block is 5" x 7.2" x 1.5". The bigger Ion i1000.4 with 4 * 140W/4ohm is 5.375" x 10.25" x 1.875" and if were cut in half (power supply/amp) would be under 6" square each section.

I'm surprised no one (that I know of) has modified an alternator to put out amplification type voltage, instead of a little over 14v charging that they do now. Yes, I've seen were you can "pump up" some alternators to generate more voltage, thus more power out of your amps (just until you reach the limit and let the smoke out). What I'm talking about is +- 50v with of course something to convert that back to 12v-14v to charge and run the rest of the car. The alternator of course would never "turn off" and you would have to have your car running to listen to your system (which I do 99% of the time anyway). 

This would save having to use a step up DC-DC converter altogether. As long as the alternator could push the amps, you could attach as many inexpensive amp modules as you wanted. And they wouldn't have to share the same heat sink or space with a conventional DC-DC converter.


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## cajunner (Apr 13, 2007)

the normal operating voltage for aircraft is 400V.

and the industry of automotive electronics is trying to get automotive power like that.

it isn't yet necessary to save on weight, (thinner copper conductors can carry power further if the voltage is high) so that the industry is motivated to change.

12V is good, the Rockford PBR series uses that voltage with "boosted rails" without having to make a separate power supply, so the technology is coming around to using low voltage.

I think the combinations of low impedance, (Bose half ohm speakers) the digital control of the PWM, and the IC architecture may combine in something, like BikeTronics gets away with such a small footprint.


I am tempted by those cheap, basic class D amps on ebay too, I have access to large pieces of aluminum channel about 4" by .5" as long as you need, 48 inches...

seems like a fun project to just lay a strip of these, two 4/chans, and 8 of the high output modules and throw a copper cover panel for looks over the top, then bolt it into the car somewhere, a structural member... maybe bolstering for the rear deck, or as torsion bar between the rear shock towers, so you can go over the bumps better...


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## Patrick Bateman (Sep 11, 2006)

Actually size is the main reason I'm thinking about this.









Right now I have a pair of two channel Tripath amps that are pushing fourteen years old. They're MONSTERS - close to a thousand watts each. They made sense when I was a passive crossover fan, and I wanted a lot of power, full range.









But now that I'm doing a lot of DSP stuff, I need a lot of amp channels, and I don't have the space for six amplifiers. I could probably fit sixteen channels of amplification into the footprint that one of those beasts takes up. Of course the Sure amps are only good for about 35 watts a channel, but there's nothing stopping me from dedicating one channel to each of my eight midbasses. (I have twenty one drivers in the current project.)


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## seafish (Aug 1, 2012)

I was kinda wondering why you don;t just use a car amp (figured it was because you simply wanted to build something) and I don't know if you are interested, but I have a NICE uninstalled by me, factory refurbished, Boston Acoustics GT2125 class A/B amp that I could sell you for a dam good deal. PM me if interested. 

GT-2125 | Amplifiers | Boston Acoustics US)


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## cajunner (Apr 13, 2007)

Patrick Bateman said:


> Actually size is the main reason I'm thinking about this.
> 
> 
> 
> ...


how big is the step up to Hypex modules from the Sure stuff?

I saw 400W Hypex, obviously they cost a lot more but there are ebay alternatives available...

maybe the idea of having a dedicated alternator running 120V is a heretofore not yet considered compromise?

you know, something that could run off a hydraulic motor that taps the power steering pump, maybe sucks 3 horsepower, or 2000 watts of boosted rails, 90% efficiency....

that would be doable for many who just need to place a couple of hoses and a spot for a compact motor/alternator, maybe the size of a soup can altogether?

with 120V on tap, you could get into all sorts of mischief...


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## Patrick Bateman (Sep 11, 2006)

cajunner said:


> how big is the step up to Hypex modules from the Sure stuff?
> 
> I saw 400W Hypex, obviously they cost a lot more but there are ebay alternatives available...
> 
> ...


The thing that's interesting about a lot of these moderately powered class D amps is that they're so damn cheap. For instance, the amp I'm using works out to less than $18 per channel. The fact that they fit in your hand is a bonus too.

If I wanted to step up to something more powerful, I'd probably be looking at this:

http://www.icepower.bang-olufsen.com/files/solutions/icepower125asx2_datasheet_1_2_20141113.pdf

But once you spend $150 for the IcePower amp board, and $50 for a power supply, you're paying $100 per channel. And that gets spendy if you need eight channels. At that point you might as well buy a Alpine Class D amp. (I imagine the folks at B&O would cringe if I compared their amps to Alpine, but I can't hear a difference between *any* solid state amps.)


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## ATOMICTECH62 (Jan 24, 2009)

I can modify an old car amp to produce any voltage you need.

I do it all the time.

Something like a Kenwood 1000 watt class d sub amp could produce enough power to run the whole car.

Speaker terminals would be converted as the voltage output.

And,I have piles of blown amps to work with.


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## Eric Stevens (Dec 29, 2007)

Patrick,

The laptop power supply will give you maximum of just over 100 watts total out of the amp module you have.

If you want to get the 100 x 4 or even the 65 x 4 @ 1% you will need much more current than 5 amps. A 5 amp supply at 24 volts is only 120 watts and the amp is not 100% efficient. I would suggest a 500 watt supply if you want full output out of the amplifier module.


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## Eric Stevens (Dec 29, 2007)

Sure Electronics' webstore 500W BOOST Converter for CAR Audio - TL494

Patrick, this is what you need for the amp board you listed.


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## Patrick Bateman (Sep 11, 2006)

Eric Stevens said:


> Sure Electronics' webstore 500W BOOST Converter for CAR Audio - TL494
> 
> Patrick, this is what you need for the amp board you listed.


You rock! That's just what I need.


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## Patrick Bateman (Sep 11, 2006)

Eric Stevens said:


> Patrick,
> 
> The laptop power supply will give you maximum of just over 100 watts total out of the amp module you have.
> 
> If you want to get the 100 x 4 or even the 65 x 4 @ 1% you will need much more current than 5 amps. A 5 amp supply at 24 volts is only 120 watts and the amp is not 100% efficient. I would suggest a 500 watt supply if you want full output out of the amplifier module.


True. I'm probably seeing half of the power that it's capable of.

I bought that power supply when I wasn't 100% sure if it would work at all.


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## TallTexan (Dec 14, 2007)

cajunner said:


> <snip> I am tempted by those cheap, basic class D amps on ebay too, I have access to large pieces of aluminum channel about 4" by .5" as long as you need, 48 inches...
> 
> seems like a fun project to just lay a strip of these, two 4/chans, and 8 of the high output modules and throw a copper cover panel for looks over the top, then bolt it into the car somewhere, a structural member... maybe bolstering for the rear deck, or as torsion bar between the rear shock towers, so you can go over the bumps better...





Patrick said:


> <snip>But now that I'm doing a lot of DSP stuff, I need a lot of amp channels, and I don't have the space for six amplifiers.


I think that's the story here: The need for multiple channels of small, cheap amplification. Each driver speaker would have a channel via DSP. No more hulking big class A/B amps of the mostly 2 channel variety, that's 80s-90s technology. Today, there are multiple companies producing inexpensive chip based choices of the smaller class D. Couple that with the maturation of MOSFETS used in power supplies, the cost per watt has never been cheaper.

So manufactures take note: give us class D amps with 6 or 8 channels of 100W each in roughly the same form factor as 2 channel A/B amps. No crossover/etc. Either we have it already in our decks or have DSP. And keep the price at most $300-$400 range.


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## thehatedguy (May 4, 2007)

Anyone see the power supply that I linked?


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## Eric Stevens (Dec 29, 2007)

thehatedguy said:


> Anyone see the power supply that I linked?


The voltage would be too high for the modules since its a bipolar supply +/- 50 volts.


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## thehatedguy (May 4, 2007)

they would definitely need to power something a little more substantial than the Sure boards...those guys are pretty far off of rated power at a decent distortion level.


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## Patrick Bateman (Sep 11, 2006)

thehatedguy said:


> they would definitely need to power something a little more substantial than the Sure boards...those guys are pretty far off of rated power at a decent distortion level.


Actually that's what's kept me going back to Tripath for years.
Due to age of the design, there's a LOT of documented measurements on the chipset.

Of course all of this is muddied by the fact that Tripath went tits up years ago, and this is some type of clone from Texas Instruments.

But I trust TI's spec sheets, and they indicate that distortion is under 0.05% if the power is kept at 35 watts or less.

Parts Express indicates a distortion level, but PE is also advertising them at some silly power level, something like 4x100watts.

I've got a bunch of these boards here, along with a "real" Tripath, from fifteen years ago. The only real difference I can see is that the "real" Tripath is way WAY less tolerant of low impedances. (Give the Tripath board anything under 4.0 ohms and it goes into protection in a hurry.)









Here's an example of what I mean. I have two of these. One is from Arc Audio. One is from Ultimate. I haven't opened them up but they appear to be the exact same amp, but with a different heatsink. That's one of the weird things about Class D amps; since the manufacturer publishes a "reference design", you can get two amps from different manufacturers and the performance is basically the same. (Same idea as video cards; when you get a Nvidia video card, the performance is basically identical if the chipset and clock speed is the same, doesn't matter what the name on the box says.)

Anyways, looking at the distortion curve, you can see that this "1000 watt amp" really CAN produce one thousand watts, if you don't mind 2% distortion. Keep it to 50% of it's "claimed" power and you're looking at a distortion figure that's competitive with Class AB. And that's what's neat about Tripath. Small size, but the distortion isn't as high as you see from a lot of Class D designs... until you push it all the way.


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## Orion525iT (Mar 6, 2011)

I started a thread here some time ago basically looking into the same thing; using bare amplifier boards and separate psu. 

What I found was that unless you need a massive amount of low wattage channels, the economics just don't pan out that well. The cost of decent regulated dc/dc converters can be fairly high, then add in the cost of the boards, the effort to wire and futz them all together, ect. Not to mention they are all bare, exposed boards that would need to be protected from moisture, contamination, stray conducting materials, ect. I had a spreadsheet that I added things up on, but i dont think I have it anymore after my hard drive bricked last month.

Bottom line, there are many options in off the self class D amps that will do the job.


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## sqshoestring (Jun 19, 2007)

Kenwood has a few very small marine amps that are class D that look interesting. Note that some are bridgeable and some are not, have 1/2/4 channel models. One of the 4ch bridged looked to be just right to run a pair of 4 ohm midbass if I ever get to put something in.

Seems to me you would be better off (or cheaper) running a standard inverter to 120v AC then convert it down to the DC you want, but I could be wrong. 

A car amp makes the DC 12v into AC power (usually at very high Hz compared to household AC power, so components are smaller), by switching the 12v each direction across the transformer, which is wound to create the voltage required for the rails. Its rectified to DC, then has some capacitors and filters to smooth the output going to the output stages of the amplifier. The 12v is switched with mosfets on the heatsink, by a driver chip that runs the PS. Actually old tech, I know someone years ago made a PS that played music directly, electronics are far better now and it can be controlled that well, but not sure how efficient it would be....and it must be difficult or patented because nobody seems to be making them lol.


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## ATOMICTECH62 (Jan 24, 2009)

Yeah,the Kicker Warhorse is one.


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## MetricMuscle (Sep 16, 2013)

I know very little about this topic but PE has these on Deal of the Day.

2.1 Hi-Fi Class D Audio Amplifier Board 2x15W + 30W 10-18 VDC

Almost too cheap not to try out.


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## cajunner (Apr 13, 2007)

MetricMuscle said:


> I know very little about this topic but PE has these on Deal of the Day.
> 
> 2.1 Hi-Fi Class D Audio Amplifier Board 2x15W + 30W 10-18 VDC
> 
> Almost too cheap not to try out.


 wow, two of these would make a nice 2-way plus rears and if you hooked it to the bluetooth board, you could hide them and take your tablet/phone source with you.


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## DonutHands (Jan 27, 2006)

MetricMuscle said:


> I know very little about this topic but PE has these on Deal of the Day.
> 
> 2.1 Hi-Fi Class D Audio Amplifier Board 2x15W + 30W 10-18 VDC
> 
> Almost too cheap not to try out.


This cant be any good can it? Ebay TA2020 amps are a bit over $20. 

This has to be absolute garbage right? Theres like 1/3 the components on this thing.


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## MetricMuscle (Sep 16, 2013)

cajunner said:


> wow, two of these would make a nice 2-way plus rears and if you hooked it to the bluetooth board, you could hide them and take your tablet/phone source with you.


That would be sweet and easy to do. Not to mention they use 12VDC directly, no need for a transformer or power supply unit etc.



DonutHands said:


> This cant be any good can it? Ebay TA2020 amps are a bit over $20.
> 
> This has to be absolute garbage right? Theres like 1/3 the components on this thing.


I have absolutely no idea how well they work but most of the reviews were positive when used as intended.
I have found Parts Express to have the best prices most of the time when comparing identical items. This goes for eBay, Amazon etc.


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## Kazuhiro (Apr 28, 2015)

I've recently been tinkering with this idea too.
I've bought various 12v - 36v volt etc amps from aliexpress lately for experimenting with my diy home speakers, and thought, why cant I do this in a car?
I have an amp case in my trunk 40cm x 90cm and 15cm tall to play with.
I was thinking of finding suitable amps with plenty of power to make a large beautiful array of circuitry (7ch). Of course not all these cheap amps run on the same voltage, so It would require multiple dc step up converters. I would have to have a power rail plan and heatsink and fan system considered. Also important would be quality voltage regulators as the signals can have quite an effect on the simpler amps I noticed. You can also find cheap tube amps with reasonable power, which could be adequate for tweets and midrange, but who knows. 
One thing I find nerving about these amps are the gauge of the input tracks/wiring. nearly all of the rca inputs, dc inputs and speaker outs can use such tiny plugs. The wires coming out of these plugs can be extremely tiny. This leaves me wondering how they can expect 10A at 12v to flow easily. This could be an easy fix, but it really stirs up the minding seeing how they are set up like this by default.


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## Kazuhiro (Apr 28, 2015)

This one people mentioned;
Sure Electronics' webstore 4 x 100 Watt 4 Ohm Class D Audio Amplifier Board - TK2050

1% thd @ 64W (1khz) on 4 ohm load. Bit high tbh, although at 50w rating it could be 0.1

I think a best way to get this done is to pick a voltage that you can find suitable high powered boards on, eg 24v dc, and buy yourself quality dc regulating components specific for it.


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## cajunner (Apr 13, 2007)

Kazuhiro said:


> This one people mentioned;
> Sure Electronics' webstore 4 x 100 Watt 4 Ohm Class D Audio Amplifier Board - TK2050
> 
> 1% thd @ 64W (1khz) on 4 ohm load. Bit high tbh, although at 50w rating it could be 0.1
> ...


why not just use the 14.4V of car electrical, and take whatever output you get?

I know with higher voltage inputs the amps do a lot more power, but if one were to simply accept a 25W output @ 14V input, the amps would work fine and definitely push more into a load than any head unit IC amp, making it suitable for multi-channel systems and small chassis design...

but then, you can probably get class D amps in the 8 channel option, fitting in the space of an old 30W/ch class AB unit from yesteryear.

The Sony deck with a 4 channel class D amp built into it, is no larger than a regular deck and it doesn't even have a dangler box like the DC-DC converter supply on older high end decks.


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## Kazuhiro (Apr 28, 2015)

I guess I have high expectations I'm weighing this project against a PPI 900.4 upgrade


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## gstokes (Apr 20, 2014)

Kazuhiro said:


> I'm weighing this project against a PPI 900.4 upgrade


Stop weighing and put the scale away, get the PPI Black Ice BA1000.4

80 x 4 @ 4~
125 x 4 @ 2~
250 x 2 Bridged @ 4~
$88 @ Sonicelectronix


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## Kazuhiro (Apr 28, 2015)

Already have 80x4, on anarchy midbass and bridged onto sub, and trust me there is no headroom. Due to postage weight there is only 60usd difference between the two. Would have to consider the ba1600.4 instead. 
Anyway it looks like I won't be going down the road of these diy boards, not enough time to fiddle or fail really.

Edit: due to shipping calculation anomalies, I can get the 1600.4 for the same price as the 1000.4


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## Victor_inox (Apr 27, 2012)

ATOMICTECH62 said:


> I can modify an old car amp to produce any voltage you need.
> 
> I do it all the time.
> 
> ...


 Nobody noticed most important post of the thread so far. 
Randy can you make me one -+48 -72 V adjustable relatively cheaply? 
350W minimum, modified old amp is fine of course.


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## Patrick Bateman (Sep 11, 2006)

Orion525iT said:


> I started a thread here some time ago basically looking into the same thing; using bare amplifier boards and separate psu.
> 
> What I found was that unless you need a massive amount of low wattage channels, the economics just don't pan out that well. The cost of decent regulated dc/dc converters can be fairly high, then add in the cost of the boards, the effort to wire and futz them all together, ect. Not to mention they are all bare, exposed boards that would need to be protected from moisture, contamination, stray conducting materials, ect. I had a spreadsheet that I added things up on, but i dont think I have it anymore after my hard drive bricked last month.
> 
> Bottom line, there are many options in off the self class D amps that will do the job.


I have the parts here, but still haven't tried it out in the car.

The amp board wound up costing about $50 and the 12v to 24v converter was $35 : http://www.amazon.com/gp/product/B00O0EDMES?redirect=true&ref_=cm_cr_ryp_prd_ttl_sol_0

It's true that you could run the amp boards off of 12V, but that would reduce their power output quite a bit.

One thing that I'm doing, which is a little unusual, is I'm running wires for 19V and for 24V. Basically I'm putting the DC-DC converters up around the dash, then running lines for 19V and 24V. This has a couple of advantages:

1) less gear in the trunk
2) Allows me to run smaller than normal power wires. (Since 24V requires half the diameter of 12V.)


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## Kazuhiro (Apr 28, 2015)

What board did you buy


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## Focused4door (Aug 15, 2015)

TallTexan said:


> I think that's the story here: The need for multiple channels of small, cheap amplification. Each driver speaker would have a channel via DSP. No more hulking big class A/B amps of the mostly 2 channel variety, that's 80s-90s technology. Today, there are multiple companies producing inexpensive chip based choices of the smaller class D. Couple that with the maturation of MOSFETS used in power supplies, the cost per watt has never been cheaper.
> 
> So manufactures take note: give us class D amps with 6 or 8 channels of 100W each in roughly the same form factor as 2 channel A/B amps. No crossover/etc. Either we have it already in our decks or have DSP. And keep the price at most $300-$400 range.


I will second that request!

Harman Kardon makes class D amplifiers with more channels than that already for auto manufacturers.

Not sure you could actually get a hold of one absent pulling it out of a junkyard or ordering as a replacement from a car dealership though. There are several different models, at least an 11 channel version. I don't think the Subaru's have as many speakers and likely use a smaller amplifier.

Not sure what class amplifier the Buick higher end Revel systems use, or if it is the same Harman Kardon as other cars.


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## Victor_inox (Apr 27, 2012)

24Volt for that board is not enough, with that converter it will sound like ****, I already tested that, with 24 Volt supply it will get about 20 real watts. it needs 30 volt to get closer to advertised and even then it`s overrated. 
I`d rather get this and adjust it to 30 V for that board, actually it could power up to 600 watt, so realistically 6/100W ch.
I messed with it for a while but abandoned that project due to dual voltage PSUs and more powerful designs.
So far best sounding D class was Hypex modules but cost is different story. B&O Ice modules is also very good but they all has 85-240 PSU build in and not suitable for car installs.


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## Patrick Bateman (Sep 11, 2006)

Kazuhiro said:


> What board did you buy


Personally, I'm using these for just about everything:

Sure Electronics 4x100W at 4 Ohm Class D Digital Audio Amplifier Board STA508 (TK2050)

I started out with a pair of these from PE, along with a 24V power supply from eBay that basically looks like a laptop power supply.

After going that route, I realized that the power supply was about half as big as it should be. It runs fine, except for that time it nearly burned the house down. So I bought another one, but the second time around I purchased the amp and the power supply directly from the manufacturer in China. (Sure Electronics.)

The latter is available on eBay here : 4 x 100W Class D Audio Amplifier T Amp w Delta 24V 350W PMT Power Supply | eBay

I've been using Tripath for just about everything for a decade now. The sub amp in my current car project is an Arc Audio Tripath amp, my home speakers are a DIY active setup using that Sure amp, and I'm also using the Sure amp for the midrange and tweeters in my current car project.


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## Patrick Bateman (Sep 11, 2006)

Victor_inox said:


> 24Volt for that board is not enough, with that converter it will sound like ****, I already tested that, with 24 Volt supply it will get about 20 real watts. it needs 30 volt to get closer to advertised and even then it`s overrated.
> I`d rather get this and adjust it to 30 V for that board, actually it could power up to 600 watt, so realistically 6/100W ch.
> I messed with it for a while but abandoned that project due to dual voltage PSUs and more powerful designs.
> So far best sounding D class was Hypex modules but cost is different story. B&O Ice modules is also very good but they all has 85-240 PSU build in and not suitable for car installs.


Random observations:

1) The description of the board on eBay appears to be completely wrong. It *appears* that the board I have uses this chip: http://www.st.com/web/en/resource/technical/document/datasheet/CD00244535.pdf

2) I never noticed, but it *does* seem that this chip can take as much as 44V

3) The manual seems to indicate that you don't want to go below six ohm with this chip. That might explain how mine nearly caught on fire. I was running something like 3ohm at the time.

4) I can't figure out why they call it a Tripath amp. It's a ST Microelectronics amp. Maybe it's a copy of the now bankrupt Tripath? Trevor Marshall - Class D Audio Amplifier Design - TDA7498 Output filters


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## Victor_inox (Apr 27, 2012)

Patrick Bateman said:


> Random observations:
> 
> 1) The description of the board on eBay appears to be completely wrong. It *appears* that the board I have uses this chip: http://www.st.com/web/en/resource/technical/document/datasheet/CD00244535.pdf
> 
> ...


Undervoltage perhaps explain overheating get that boost controller I linked off ebay for 11 bucks, bump up voltage gradually and see how chip behaves.
Sure electronics makes very reliable D class boards. I`m in process of adapting their highers power amplifiers to in car use. 
Hypex is still my first choice but we all need more power, don`t we.


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## Kazuhiro (Apr 28, 2015)

I guess that power supply is only for testing eh? I may invest in one just like it soon, good resource. I have a similar to laptop supply at the moment, 32v 4a so around 200w and hasnt melted yet, then again i am only running two channels at home. 

I still dont like the look of the THD ratings on that amplifier. Would only be suitable for high efficiency or smaller speakers?


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## Patrick Bateman (Sep 11, 2006)

Kazuhiro said:


> I guess that power supply is only for testing eh? I may invest in one just like it soon, good resource. I have a similar to laptop supply at the moment, 32v 4a so around 200w and hasnt melted yet, then again i am only running two channels at home.
> 
> I still dont like the look of the THD ratings on that amplifier. Would only be suitable for high efficiency or smaller speakers?












huh? It's under 0.2%


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## Kazuhiro (Apr 28, 2015)

never saw that lol. All i saw was in the listing, Output power (using 30V power supply): 64W x 4 @ 4Ω (1% THD+N), 108W x 4 @ 4Ω (10% THD+N)

these are peak values right? so rms is this over sqrt2 correct?

As for the load problem, I suppose it has enough headroom power (for tweets and 3") to add perhaps a high rated 1 ohm in series with whatever drivers are below?


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## TommiAn (Sep 5, 2015)

Can you please help me to understand more about your problem? for what rating are you looking for? What are the devices you want to attach with it and what are their specifications?


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## DonutHands (Jan 27, 2006)

PPI Phantom 900.4 for me in the new install. Might be a bit bigger than what you are needing, but its a finished product, ready to go.


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## Patrick Bateman (Sep 11, 2006)

My little project worked out nicely.
Today I hooked it up in the car for the first time. (I've been using these amps at home for a couple years, but this is the first time I've used it in the car.)

It worked on the first try, and the noise level is arguably better than I've ever experienced in a car.

Four channels of class D for about $80 isn't too shabby. It's also cool that you can build the amp right into the loudspeaker if you wanted to - you could make a power loudspeaker for the car.


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## mfenske (Feb 7, 2006)

Patrick Bateman said:


> My little project worked out nicely.
> Today I hooked it up in the car for the first time. (I've been using these amps at home for a couple years, but this is the first time I've used it in the car.)
> 
> It worked on the first try, and the noise level is arguably better than I've ever experienced in a car.
> ...


Patrick, can you post a quick parts list? I seem to have missed it.


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## Patrick Bateman (Sep 11, 2006)

Check out post 41 and 45.

Under $90 for four channels of class D amplification.


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## Onyx1136 (Mar 15, 2009)

Patrick Bateman said:


> Check out post 41 and 45.
> 
> Under $90 for four channels of class D amplification.


I didn't follow the whole thread. $90 for how many watts total? At some point one has to consider price per watt. If we're at 90 watts and equaling a dollar per watt, then the value is pretty good. But, as the wattage drops the value decreases proportionately. If we're only getting 45-50 watts then we've hit the $2/watt price point, and any perceived value has almost vanished. Once we're paying more per watt then we would for a commercially available amplifier, it's become an exercise is futility.


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## Rrrrolla (Nov 13, 2008)

In your car, are you running the amp directly off 12V or did you use a dc/dc converter to raise the voltage (and I'm assuming avoid noise in the system). These are a phenomenal deal if they sound ok directly off the car's 12V. It sounds like it has a pretty typical power supply built into it, if you run it at a lower voltage, it will draw more current, higher voltage, less current. Most units like this run a little more efficiently at higher voltage inputs because there is less I/R drop in the windings of transformers, on the traces of the board, etc. But its should be pretty dam close to the same output with 12V as it is with 30V. Mostly I am curious if it is noisy in a car connected directly to the battery?


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## Patrick Bateman (Sep 11, 2006)

Rrrrolla said:


> In your car, are you running the amp directly off 12V or did you use a dc/dc converter to raise the voltage (and I'm assuming avoid noise in the system). These are a phenomenal deal if they sound ok directly off the car's 12V. It sounds like it has a pretty typical power supply built into it, if you run it at a lower voltage, it will draw more current, higher voltage, less current. Most units like this run a little more efficiently at higher voltage inputs because there is less I/R drop in the windings of transformers, on the traces of the board, etc. But its should be pretty dam close to the same output with 12V as it is with 30V. Mostly I am curious if it is noisy in a car connected directly to the battery?


It's possibly the quietest amp I've had in my car.

It's hard to say, as I've only had one amp in this car before, and prior to that, I drove Hondas, which are notoriously noisy.

I'm stepping up the voltage to 24V via a DC-DC converter that cost about $30 at Amazon. Link is two posts above here. Copper is expensive these days, and one of the cool things about doing 12V to 24V is that you could do the conversion at the front of the car, then run 24V lines to the back, using wiring that's half the size you'd use for a 12V amp. That alone could save you $5-$10 in wiring. Same idea as laptop computers; there's a fat 120V cord that goes to the power supply, and a tiny 19V wire that goes to the laptop. No good reason to put the power supply near the speakers, put the power supply somewhere else, preferably closer to the battery to cut down on noise.

You *could* run it at 12V, but you'd wind up with much less power.

Victor Inox(sp?) knows much more about power supplies than I do, and he recommended a different unit. His advice is definitely worth considering, I am no expert at electronics.


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## Rrrrolla (Nov 13, 2008)

Perfect! Thank you for the info. I drive a prius c now, and am just getting started with the stereo and am interested in trying out some dsp line arrays, etc, but like you, I will be needing LOTS of amp channels to do it. I'm just a little lost as to why this particular amp makes so much more power at 24V than it does at 12. I work on marine electronics as part of job with the coast guard, and when a unit says it will run from 9-30V (quite typical in that environment), the performance is the same at any voltage, but the unit pulls more current at a lower voltage for obvious reasons. But they all have internal switching mode power supplies that are very efficient. I can see it making slightly less power at lower voltage, but nothing significant. My main concern is resistance to noise in my undoubtedly extremely noisy car. I would love to know if your amp sound just as good directly from the battery. Could ya run out there and try that real quick for me? LOL, jk, I'll be buying one myself and doing some testing. For the price, its worth experimenting! Nice find!


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## Patrick Bateman (Sep 11, 2006)

Over on Facebook, there was a big discussion of "Class A amps for the car." 

And I was kind of incredulous that nobody is _building_ amps, because it's ridiculously easy to do.

For instance, the Class D amps that I use, I can literally assemble them in under fifteen minutes. It really is as simple as:

1) get an amp

2) get a power supply

3) plug the power supply into the amp

Full disclosure, the reason that this process is so ridiculously easy is because *I'm not building power supplies.* I just buy one, and I plug it in.

But from my perspective, the most dangerous part of build an amp is the power supply, so that's one of the reasons I just buy the darn thing. I don't want to blow myself up.

But if you outsource that part of the process, building an amp isn't much more difficult than plugging a power supply into your phone or your laptop. Again, two step process:


1) get amp

2) get power supply, plug into amp. Boom, you're DONE.

If that seems reasonable, than it opens up your world to a whole slew of amplifiers that were otherwise unavailable in the car. You want to run Class A in a car? _No problem._ You want to run single ended in a car? _No problem._ You want to run a studio DAC in your car? _No problem._

Nearly all electronics run off of DC, so you just do a DC to DC conversion. Easy.

Again, I'm not an EE, so maybe there's some piece of the puzzle I'm missing here. But I've been running amps that I personally built for half a decade now, and I built them as I describe here. I use the same amp for my car and my home. At home, I use a AC to DC power supply, and in the car I use a DC to DC power supply. But the amp board is identical.

For instance, if you want to run Class A in a car:










For instance, this is a Class A amp called "the amp camp amp." The cost is $129 here : https://diyaudiostore.com/products/amp-camp-amp-parts-kit-only










Here's the schematic. A very low parts count, as you can see.










Most Class A amps are huge and expensive. This isn't because the amp is expensive, it's because the power supply and the chassis is expensive. Class A runs very hot, so you need an enormous heat sink. It's pretty easy to spend $400 on a heat sink. But there's another solution: *use a fan.* We're in a freaken car, nobody is going to hear a fan. You wouldn't use a $400 heatsink on the CPU in your computer, why use one on an amp? I guess it _might_ make sense at home, but even then it's hard to see the downside of using a fan. I guess one danger is that you might burn your amp up if the fan dies, but it's a risk I'm willing to take, I haven't had a fan failure in years. 

The other expensive part of an amplifier is the power supply. And in this case, the builder used a switching power supply for a laptop. Yeah, I know that's kinda heretical. SMPS has come a long way. I've used a SMPS and I've used a conventional power supply, personally, I couldn't hear a difference. YMMV.

For a car, we need a DC to DC power supply, so the laptop thing won't work. Here's a DC-DC power supply from Amazon, for $20 : https://www.amazon.com/Converter-Regulator-Adapter-Vehicle-DC9-20V/dp/B01EFUHGMU










For comparison's sake, here's a single channel Class A amp, using a conventional heat sink and conventional power supply. Note that the power supply is significantly more complex than the amp. PS is on the left, amp is on the right.

Hope that helps. Building your own car amps is shockingly easy, if you use off-the-shelf power supplies. You can also do crazy stuff, like build yourself a twelve channel amp, or build an amplifier / DSP / DAC combo.


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## JCsAudio (Jun 16, 2014)

Wow, thanks Patrick, this is awesome information!


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## 94VG30DE (Nov 28, 2007)

Hey Patrick, where did you end up installing these? I'm trying to figure out if I can shove them in the dash DIN pocket under the the single-DIN head unit. Dimensionally seems like it will fit if I can remove the fan and move it to a different spot in an enclosure (while still keeping air moving over the heat sink.


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## Patrick Bateman (Sep 11, 2006)

I put them under my seat. I haven't noticed much heat coming off them, but I've never removed the fan.


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