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

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#221
Oh you hadn't said you'd had your own boards made - Kubeliks I meant, you did mention about monoAMPs now my memory's been jogged. So I was trying to figure out your context. Now all becomes clearer 🙂

Kubelik using TH resistors I suspect would be at least twice the area of PCB given there are around 80 resistors on it. I would have to look into what non-SMD capacitors could be used.
 
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#223
Hi guys. Hope all are well. Slowly populating my bare pcbs for the monoamp R3, seem to be much more proficient and confident with 0805s!
Do the output inductors really have a polarity or 'direction'. Shertzey got creative fitting the big Wurths to his R3 boards as one was 'flipped.' I was just going to mirror one of the big inductors so they would both mount 'face up', rather than flip it and attempt to get to pin#1.
Surely it is just a coil of wire?!
 
#225
Thanks Richard.
I've been procrastinating far too much over power supplies but its taking far too long, along with other projects , so will just build as per your design for momoamp r3 for now and worry about improving U3 later.!
 
#226
abraxalito said:
Orders now are open on TDA8932 mono amp kits - feel free to PM me.

Preferred payment method is via Transfer Money Online | Send Money Abroad with TransferWise which typically adds a 2% fee. Our receiving currency is either Euro or USD. PayPal may also be used (in USD) but subject to an additional fee.

Kit for a pair of mono amps with transformer input : 210RMB ($32)

We are at present only selling amp kits in multiples of two. Kits contain all the parts you need to build 2 off mono amps, excluding power supply. Most of the parts are SMD, the smallest are 0805. If you've only done conventional (through-hole) soldering before this kit could be a handy introduction into surface mount tech. The trickiest part to solder is the TDA8932 itself, it has 32pins on a 1.27mm pitch.

Shipping is in addition and depends on your location and speed of service.

The amp is rated at 25W into an 8ohm load and is BTL - the power rating is a fairly conservative one on music but its not been designed to deliver 25W continuously. The amp IC contains thermal overload protection should its temperature rise too high. The suggested power supply (extra) is a single 24V @3A switching brick for each channel. Thus a stereo setup should have a 24V/6A supply.


The original development thread with schematic and technical background is here : Transformer input TDA8932 mono amp


TDA8932 datasheet is attached for those wishing to look in more detail.
Click to expand...
Hi, can these be purchased as ready built and tested?
Thx
 
#230
Hello Richard,
Have you completed the tests of the new TDA8932 25W / 8R mono amplifier powered by transformer with oversized inductances and capacitors and more filtered power supplies?
How does it work and what's new?
Are you preparing a kit and what cost could it have?
Regards
Guglielmo
 
#231
Hi Guglielmo - I built two of the 'to 11' amps and listened to them, yes they work fine. I was using a lower noise regulator than the LM317 which is on the original monoAMP. It did sound a little clearer than the monoAMP so I swapped the LM317 out of my desktop monoAMPs and got a similar slight improvement. It seems to me that the other changes (bigger caps, fancy inductors) don't make an audible difference. So I now use modified monoAMPs as my reference, not Amp211s.

So far no kits are in the pipe for Amp211s as the parts are much more expensive than for monoAMP so would call for a significant capital outlay and I've yet to see enough interest to justify that, given that to my ears the improvement over monoAMP is limited to the regulator upgrade.
 
#234
Ah, ok, so it is the reg, you mentioned a few posts earlier. Yes, as I currently use your amp design in my system, I would like to get more details, in order to make it easy enough for me to replace the 317 reg. When listening, I always think, slightly more details would be welcome. Enlightenment would be appreciated 🙂 BR, Ernst
 
#235
I found the schematic on my disk, but turns out the component values are just place holders. Means I've not updated it since we did the PCB layout for it - I'll get on to that and post it when done. There are PCB gerbers too.

The improvement isn't a big one so I'm curious to ask - what are you using for source? Could be your lack of details isn't the amp. For example : if you were using a MkI version of the Deca DAC then the upgrade to MkII is rather a lot bigger than updating the reg on the monoAMP.
 

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#236
Richard, I use an ADI2PRO FSRBE as a DAC in this system. It is a pretty clean and transparent sounding peace of equipment. So I do not see the slight lack of detail in the DAC.
It is not a big deal, yet I would be happy to increase clearness a little bit.

Thanks for the circuit. So this is, what you replaced the LM317 with. Looking forward to the gerbers or a pcb. 🙂

Cheers, Ernst
 
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#237
ernesternest said:
So this is, what you replaced the LM317 with. Looking forward to the gerbers or a pcb. 🙂
Click to expand...

The schematic shows an LM317 but that's there merely for the mechanical footprint so this can fit where an LM317 exists on a PCB. I will look out the gerbers.

Please note this is rather an experimental design and it does run rather hot with the PCB layout we currently have. I'd not recommend using it inside a box where the internal temperature is significantly above room temperature. I keep mine in the open. If I were to respin the PCB I'd increase the radiating area.
 
#238
Hm, ok, will check temperature in my box. It is 1 HE in height and includes 2 big SMPS thingies. Have a look at #41. Maybe some kind of heatsinking via the chassis might be possible...? Richard, I am not in a hurry. If you think, you would rather redo the design in order to support your kits, I am fine by waiting for that.
Yes, I did think that the LM317 would have to leave, yet it took me a few moments.
Cheers, Ernst
 
#239
There are quite a few PCBs in line now for production and as I'm not planning on selling the regulator anywhere at present the PCB re-spin will be quite a long time coming. It'll come if I see an opening for a product though.
You could have a chat with @Shertzy to find out what regulator he's been using, I understand its a Sparkos one. He did mention an improvement with that over the LM317.

If you wanted to build your own regulator on perfboard, the 2N2905A is an acceptable substitute transistor for the hot ones in the schematic and that's available in TO-5/TO-39 package which you could heatsink with a clip. This would be a way to get more thermal headroom than my PCB layout.
 
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