The parameters are an interesting challenge.
Enough output power to avoid over-capacity distortion.
Enough potential instability to procure actuance for realism
Enough stability to procure practical tonality for usable output.
We need all 3 parameters, and they are usually in conflict.
Bi-amp, tri-amp is a ready solution for when the available parts aren't available with the practical parameters well balanced.
However, I have DeVore type hybrid series crossovers that aren't going to be bi-amped (the hookups don't exist). So, for me, there will be more effort at One amplifier. That's alright--good speaker design almost always opposes good amplifier design, so it wasn't a surprise.
It seems that my next speaker build should be a 3 way built for tri-amp capability. That is a ready path forwards. Thanks again for your help.
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Has anyone seen this little guy? I'm tempted to get myself one. May be a little pricey but..
TDA8932 2X15W Dual channels wireless Bluetooth Audio digital amplifier board For modified Ceiling mounted bluetooth speaker-in Other Consumer Electronics from Consumer Electronics on Aliexpress.com | Alibaba Group
TDA8932 2X15W Dual channels wireless Bluetooth Audio digital amplifier board For modified Ceiling mounted bluetooth speaker-in Other Consumer Electronics from Consumer Electronics on Aliexpress.com | Alibaba Group
It looks suited to a 2.1 or bi-amp system or extremely compact system.
If have seen the photo correctly (possibility for error exists), the output caps are 16v 1000u.
The 1000u volume for output caps is appropriate for most 3" and 4" sized speakers. Had you a larger speaker then you'll be wanting a larger capacitance. Full size speakers need 6600u~6800u. 0.7 cu ft speakers could do with 4400u~4700u. If the cap were made, neither too large, nor too small, to suit a specific speaker, then the functionality of that speaker is enhanced. There is some sport to that. You may want higher capacitance.
For electrolytic caps carrying both DC and AC simultaneously, half of the AC could get added to the DC (not all cases), therefore the general rule of thumb is that the DC not exceed 2/3rds of the caps rating. That's 11v, but they probably anticipated using 12v, as the literature states. The caps can easily be swapped for higher voltage versions. Also, 2/3rds is just about maximum for the pulse reverse tolerance of polar caps, a feature that AC audio signal is certain to make use of. You may want a higher voltage tolerance capacitor.
Although a little short of some goals, 2200u 25v caps will fit the space provided, plus it is possible to parallel more, under board, reaching targets of 4400u for 0.5cu ft ~ 0.7cu ft speakers, and with a bit of creativity, TWO caps can be put under-board, which added to to the one fit through the vias results in 2200u||2200u||2200u, aka 6600u suitable for full size speakers. Multiple parallel same model cap is the easiest way to parallel for higher resolution. Two limits apply--if it is before or after gain is applied and the tolerance/variance % of the caps. This area is after gain has already been applied, so the matter is not complicated. Do you have gel flux to make the soldering work?
If a different solution is needed, feel free to replace the output caps with pins so that you can add daughter-cards to the new pins with your own capacitor array solution onto those pins. That's quite a nice solution if you already own a plentiful amount of seemly caps that happen to be too bulky to fit into the board vias.
If increasing the output cap, capacitance, it is possible that a need for increasing the 47u standby delay to 100u or more, could happen; because, it may take more delay time for the new 4400u or 6600u output caps to charge up.
The good news is that the soldering for any of this is far easier than modifying one of the bridge boards to SE mode. Normal size soldering irons are going to work just fine.
There's quite a few other things that I saw on that board, but additional speculation is not important at this time, because the other items are not detrimental to audio. So, it is just needful to mention that the caveats of output caps include enough voltage tolerances to do the job, suitable bypass for good treble (easiest to parallel same||same model cap), and that a given capacitance is optimal only when it matches a given speaker (in which case the results are likely better with the caps).
The board looks both fun and useful to me; however, the most straightforward usage (without modification) would involve small speakers.
Thanks, Daniel..
I will assume all should be good in a small boom box scenario, using 3-4 inch speakers "As Is"? That would be my goal..
I've been dealing with 5 volt amps for a couple of years now. I can make those little buggers sound pretty good and last for days on a bank battery. I find at times I wish I had just a little more "Umph" and the only way is to move up in the voltage. I guess I'll be ordering one to play with..
I will assume all should be good in a small boom box scenario, using 3-4 inch speakers "As Is"? That would be my goal..
I've been dealing with 5 volt amps for a couple of years now. I can make those little buggers sound pretty good and last for days on a bank battery. I find at times I wish I had just a little more "Umph" and the only way is to move up in the voltage. I guess I'll be ordering one to play with..
Thanks, Daniel..
I will assume all should be good in a small boom box scenario, using 3-4 inch speakers "As Is"? That would be my goal..
I've been dealing with 5 volt amps for a couple of years now. I can make those little buggers sound pretty good and last for days on a bank battery. I find at times I wish I had just a little more "Umph" and the only way is to move up in the voltage. I guess I'll be ordering one to play with..
Yes, it should work great for that boom box. However, you'll need more than 5v.
A little bit OT but - if you only have 5V to play with, these are a steal, at 5 for $1.50 : 5pcs/lot PAM8403 Super mini digital amplifier board 2 * 3W Class D digital amplifier board efficient 2.5 to 5V USB power supply-in Other Electronic Components from Electronic Components & Supplies on Aliexpress.com | Alibaba Group
Purchased a 12 volt LiPo jump start battery and tested it yesterday on one of the work vans. (V6 Chevy) Disconnected the lead-acid battery completely and inserted the LiPo. It started the van 4 times with the headlights on. I'm impressed. Good deal for $40..
This will be included in my next project..
http://www.amazon.com/gp/product/B010WW8HDM?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00
This will be included in my next project..
http://www.amazon.com/gp/product/B010WW8HDM?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00
Thanks abraxalito,
I have tried both a 15v, and a 24v ps. only one of the two amps is working. When you say check the DC voltage at the outputs, you mean the speaker outs? I only get a few mv at the speaker outs from both boards.
The chips get hot on both boards with 24V, but no sound out of one board.
As the supply to the boards is single-ended and audio signals are bipolar, the no-signal output from the speaker outs should be half the supply voltage. Be sure you're measuring DC volts, not AC and measure each output relative to 0V from your power supply. The working one should read 7.5V or 12V depending on which power supply you've connected.
Ok... Thanks for your patience! The board that works has 12v at the output (24v PS). The one that doesn't work has full 24V at the output.
I'd do a test for a short between your +ve power input and the output pins in that case. Both of them are at +24V? I've never seen that myself - I have had faults on various of these boards but so far all of the faults I've introduced myself through solder splashes when modding. The pitch of many of the components is fine (0603) so its easy to miss shorts.
On the board that has no sound there is a short (continuity) between the power input + and output - pin. Yes, there is 24V at both output pins.
The board that does work has 12v at BOTH output pins, but has no short between input + and output -
The only soldering I have done is wire connections, no component changes. I looked at every solder connection with high magnification, and I don't see any problems (shorts). I removed the power input, and the output wiring and cleaned the holes of all solder. The short between power input, and the output remains??
I just hooked up one of my boards and it's DOA - no sound at all, chip gets a little warm. So did some probing around and the +ve speaker out measures 2.0ohms with respect to +ve power supply pin. I looked at traces and solder joints - all look good so must be internal short in the chip? Will test out second board next but that board does not show any path between the same two pins.That's too bad, even at $3.50 it's disappointing... my first lemon from Sanwu.
Edit: tested second board and it works fine. Sounds very nice actually - even with a cheap (not tiny) 19v smps. Bass is actually very good, vocals are nice and clear.
Edit: tested second board and it works fine. Sounds very nice actually - even with a cheap (not tiny) 19v smps. Bass is actually very good, vocals are nice and clear.
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Just a note about these boards, the bluetooth "connecting" sound is some pretty mangled english by a chinese woman. Wish they could just leave the default beeps.
I have been listening to this amp for past couple of hours and my opinion of its sound quality has increased. The OP is correct about the nice smooth non fatiguing sound. The lack of fatigue may also be in part due to the standard 10R+470pF bootstrap snubber as standard issue. I noticed it upon visual inspection and confirmed in Fig 37 of spec sheet.
http://www.nxp.com/documents/data_sheet/TDA8932B.pdf
The spec sheet touts no on/off pop and I can confirm that it is absolutely quiet on power on or off.
Nice amp!
http://www.nxp.com/documents/data_sheet/TDA8932B.pdf
The spec sheet touts no on/off pop and I can confirm that it is absolutely quiet on power on or off.
Nice amp!
I have always wanted to try one of these - they seem overkill perhaps at 150watts.
Booster 12/24V 8 32V to 9 46V DC Step up Voltage Converter 150W Notebook Mobile Regulated Power Supply Module #090438 30369-in Integrated Circuits from Electronic Components & Supplies on Aliexpress.com | Alibaba Group