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Transformer-fed TDA8932 25W/8R mono amp kits

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#41
I start in way like that: PXL_20210426_065436528.jpg
 
#42
Wow - those power supplies rather dwarf the amps. Are they Meanwells?

I started out using a Meanwell (after graduating from my bench supplies) but for a boxed up amp I'd veer towards an open PCB design like this : 24V3A????? 24V70W?????? AC-DC???? 110/220?24-???

Meanwell supplies will certainly have safety and EMC certification, can't say anything with confidence about PCBs from Taobao though. Just this one is far from being the cheapest and isn't filled up with white gunk so at least the parts used are clearly visible.
 
#44
One channel is on.

Hi Richard,

one channel is playing music 🙂 the other one is not.
There is the second led constantly on and a 7V offset on the speaker output.
Would be happy to have guideline to look for the failure.

Thanks and regards

Ernst
 
#45
Assuming that 'second led' means the red LED that's a sign that the amp chip hasn't come out of reset. Which most likely means its environment isn't as expected.

First thing to check is the supply voltages - pin2 (middle pin) of the two regulators (U3 & U4), relative to 0V. They should be around 21V. Then check C6 positive side, it should be around 2.2V.
 
#46
Thanks Richard,

both channels are measuring the same and both channels are working now as they should. Haven't checked, if the second one makes music, yet the red led disappears on both now and there is no DC on the speaker output. While measuring I noticed some bad solders at the TDA and after resoldering, it was ok. So I am keen to listen to music via this amp this evening. 🙂

Thanks and regards

Ernst
 
#50
I've been using the connectors and so far haven't had any issues. We may swap over the connector type though to versions with polarisation tabs and use crimp shells to mate with these. The crimped style of connector seems a lot more robust.
 
#51
This amp is surprisingly powerful without the heat of the class A amps I usually run. And so tiny.
Currently playing on some almost 40 years old Tannoy 10" Monitor speaker and later going to drive Bastanis open baffle. Promising so far.

Yes, I thought about that polarized option.

Cheers

Ernst
 
#52
Hi Folks!

I received my amp-kit a few days ago. Treated very well by Richard! Everthing perfectly labelled and packed!

Putting the parts together was a pleasure again. Went smoothly without interruptions.

After giving it a prolimenary psu, 24Volt, and connecting it through a 47uF cap with the Phideca dac, it was a surprize to me, that a , to the eye simple amp, could be that musical! Good balance and mighty powerfull. No hiss, hum, cracks or distortion, to the ear.

The combo throws its musical intensions at a set of fourty years old Quad ELS 64, and with success!
I love the Dac/Amp combination as much as I did the separate Decadac already.

I keep an eye on you, Richard, so you know.
And thank you for now....
 
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