I have a 650W 24VDC switching supply, so plenty of current on tap.
I would like to build a small stereo class d (or integrated) amplifier with it.
I'd like 100W+ at 1% HD and 4 ohm stability. Anybody recommend a module that will work well?
What I seem to running into is either not enough voltage in the supply for the power I want, or not enough power from what I have available in the supply.
Thanks for any recommended modules...
Wolf
I would like to build a small stereo class d (or integrated) amplifier with it.
I'd like 100W+ at 1% HD and 4 ohm stability. Anybody recommend a module that will work well?
What I seem to running into is either not enough voltage in the supply for the power I want, or not enough power from what I have available in the supply.
Thanks for any recommended modules...
Wolf
You could ask JLE if this can run at 24VDC. Does your supply have a trim pot to adjust the output voltage?
https://www.sylphaudio.com/product/sylph-d400m-tpa3255-mono-single-supply-48v-rtr-amplifier-module
https://www.sylphaudio.com/product/sylph-d400m-tpa3255-mono-single-supply-48v-rtr-amplifier-module
@wolf_teeth, you’d need more than 24VDC with TPA3255 to reach 100W at 4Ohm. See the data sheet charts attached.
Either in BTL (2 channel output per TPA) or PBTL (1 channel output per TPA) would require 30V+.
You could use one of those DC buck converters (many Amazon options) and dial up the voltage if you really want to keep that power supply. One buck converter per amplifier board may work for you. Those things have been reported to be noisy, but I’ve only used lower power ones. You could add a Mark Johnson SMPS filter to the output, but then you’re daisy chaining lots of things to focus on one power supply.
Either in BTL (2 channel output per TPA) or PBTL (1 channel output per TPA) would require 30V+.
You could use one of those DC buck converters (many Amazon options) and dial up the voltage if you really want to keep that power supply. One buck converter per amplifier board may work for you. Those things have been reported to be noisy, but I’ve only used lower power ones. You could add a Mark Johnson SMPS filter to the output, but then you’re daisy chaining lots of things to focus on one power supply.
Attachments
I'm not latched to one amplifier chip or another. Seems I can get ~120W with some 400W boards at my supply voltage, but the THD is climbing to 10% by that point.
I'm kinda wondering what's the use case for this amplifier.
You really need 100W at 1% THD constantly for the speakers?
You really need 100W at 1% THD constantly for the speakers?
Those numbers are pure marketing and useless.
Post #5 explain it, so a good quality amp board will need more voltage to give you something decent.
Realistically you can get a fairly good sounding 15 to 25W amp with a TPA3116 type of chip.
But at the end we don't know what kind of power supply you have, model number will be useful.
24V in bridge is 48Vp-p at best. 24V peak is 17V rms which is 72 Watts into 4 Ohms.
100W into 4 Ohms requires 20Vrms which is 28.28V peak (56.56Vp-p) (minimum)
At 27.6VDC (supply max), you can get 95.22 Watts into 4 Ohms maximum, which is within 0.5dB of 100W, ie don't sweat a couple dB.
1dB is about 26% power, ie the difference between 74W and 100W is just barely noticeable.
100W into 4 Ohms requires 20Vrms which is 28.28V peak (56.56Vp-p) (minimum)
At 27.6VDC (supply max), you can get 95.22 Watts into 4 Ohms maximum, which is within 0.5dB of 100W, ie don't sweat a couple dB.
1dB is about 26% power, ie the difference between 74W and 100W is just barely noticeable.
The enjoyment/value proposition of building a small class D amp is pretty low IME.
I do enjoy woodworking and design; but pure assembly and soldering (without design), well not so much.
Here’s a TPA3255 you can buy, which includes power 36V 6A supply for USD $129,
https://www.aiyima.com/products/aiyima-a08-pro?variant=39811010756683
Clocks in at just 100W into 4 ohm:
https://www.audiosciencereview.com/forum/index.php?threads/aiyima-a08-pro-amplifier-review.38720/
I concur with Steveu; a dB (even or 2) not worth losing sleep over. (some decades ago I wired my Rod Elliot P3A (https://sound-au.com/project3a.htm a 60Wpc class A/B amplifier for 90W into 8 ohm; and it really wasn’t worth the effort of the extra 1.75 dB)
http://www.sengpielaudio.com/calculator-gainloss.htm
With your power supply, since you already have it @wolf_teeth ; you’d get more for less by building a multichannel eg. 5-6 channel TPA3255
75W x 6 (4 ohm).
Come to think of it; a 6 channel Rod Elliot P3A is would also very nice. It sounds so soft and sweet in the highs. Just all there without a hint of harshness. I try to avoid superlatives in describing audio but it’s otherwise hard to explain why one would build a P3A when low cost high efficiency alternatives exist.
I do enjoy woodworking and design; but pure assembly and soldering (without design), well not so much.
Here’s a TPA3255 you can buy, which includes power 36V 6A supply for USD $129,
https://www.aiyima.com/products/aiyima-a08-pro?variant=39811010756683
Clocks in at just 100W into 4 ohm:
https://www.audiosciencereview.com/forum/index.php?threads/aiyima-a08-pro-amplifier-review.38720/
I concur with Steveu; a dB (even or 2) not worth losing sleep over. (some decades ago I wired my Rod Elliot P3A (https://sound-au.com/project3a.htm a 60Wpc class A/B amplifier for 90W into 8 ohm; and it really wasn’t worth the effort of the extra 1.75 dB)
http://www.sengpielaudio.com/calculator-gainloss.htm
With your power supply, since you already have it @wolf_teeth ; you’d get more for less by building a multichannel eg. 5-6 channel TPA3255
75W x 6 (4 ohm).
Come to think of it; a 6 channel Rod Elliot P3A is would also very nice. It sounds so soft and sweet in the highs. Just all there without a hint of harshness. I try to avoid superlatives in describing audio but it’s otherwise hard to explain why one would build a P3A when low cost high efficiency alternatives exist.
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Thanks, Steve, you fully answered my question. I'm aware of the power for output, but I was thinking far less than that. In the documentations surrounding the Sure modules, I think I can get close to what I was targeting, and the current on tap should hold out for the 2x300+1x500 module. I considered the 100x6 module too, but it appears they may not be long life boards.
The main reason I was looking at 100W ballpark was related to some 50W and 75W amps not quite being enough at times, but that could depend more on the architecture. Just seemed that the amps did not quite have the stomach for their upper range.
If I had not seen the great deal on the high current PSU, I wouldn't even be considering this. I'm normally a speaker guy....
Thanks for the replies.
The main reason I was looking at 100W ballpark was related to some 50W and 75W amps not quite being enough at times, but that could depend more on the architecture. Just seemed that the amps did not quite have the stomach for their upper range.
If I had not seen the great deal on the high current PSU, I wouldn't even be considering this. I'm normally a speaker guy....
Thanks for the replies.
Ah, I misunderstood too. I didn’t know he wanted 100 W with a 4 ohm load, just that the amp itself would be stable at 4 ohm. But I guess it wouldn’t make sense to try to use it at 2.5 ohm or whatever, while the amp would be stable only to 4.
At the moment I am trying just to make sure it works before I get any further. I have a 4A brick plugged into it, and I can't seem to get more than 0.35VAC on all 3 channels. I then found what I thought were the LEDs are probably actually Phillips topped pots. Twisting them appears to not have a stop at the other end, trust me I was very gentle, and I can only briefly get 0.6VAC output in turning them. I am just running radio static at 0dB (very loud) for signal.
When I plug in the supply, the 2 LEDs come on and go out. When I unplug it, same thing. If I short the SD terminal to ground, which I read is how the standby function works, the LEDs stay on, but I get no voltage at the output.
I feel like I'm missing something obvious to the initiated, but I don't know what that something is.
Help?
When I plug in the supply, the 2 LEDs come on and go out. When I unplug it, same thing. If I short the SD terminal to ground, which I read is how the standby function works, the LEDs stay on, but I get no voltage at the output.
I feel like I'm missing something obvious to the initiated, but I don't know what that something is.
Help?