I recently got a YuanJing brand low cost TDA8920 based board from ebay. This is a fairly basic low frills build but worth documenting for those interested.
I'd already wired up the case for my second ConnexElectronics TDA8920 board when I managed to fry the board. Out of curiousity I decided to check out this lower cost board that was going cheap cheap ($19USD + $9USD postage), as I could use the transformer I'd already mounted in the case as they are similar units.
This is the board on ebay:
TDA8920 Class D Amplifier board/ audio Power AMP 2X100W - eBay Power Amplifiers, Amplifiers, Home Audio, Electronics. (end time 19-Jul-10 02:14:45 AEST)
It has a smaller heatsink than the connex module, and smaller PSU 4700uF caps.
Initially it sounded OK, but not as good as the Connex module, quite a bit more grainy.. also interestingly it uses 5W power even when silent, and hence (with the smaller heatsink) runs a lot hotter.
Tracing out the circuit it appears it is pretty much the reference implementation of the TDA8920 circuit, with a volume control tacked on. Though the PCB mentions 0.680uF caps, they have used values 0.470 as per the reference circuit
Some minor tweaks I have made to the unit include:
The overall result now sounds better. Not incredible but quite OK for a modded cheapy. Interestingly this unit doesn't seem to have what I call the "Diana Krall" bug (faint fizz audible on very soft piano notes) thats been noted on other TDA8920 based modules. I'm using a basic plastic enclosure from Altronics, 160VA toroidal transformer, and have the ESP groundloop protection in there as well.
I'd already wired up the case for my second ConnexElectronics TDA8920 board when I managed to fry the board. Out of curiousity I decided to check out this lower cost board that was going cheap cheap ($19USD + $9USD postage), as I could use the transformer I'd already mounted in the case as they are similar units.
This is the board on ebay:
TDA8920 Class D Amplifier board/ audio Power AMP 2X100W - eBay Power Amplifiers, Amplifiers, Home Audio, Electronics. (end time 19-Jul-10 02:14:45 AEST)
It has a smaller heatsink than the connex module, and smaller PSU 4700uF caps.
Initially it sounded OK, but not as good as the Connex module, quite a bit more grainy.. also interestingly it uses 5W power even when silent, and hence (with the smaller heatsink) runs a lot hotter.
Tracing out the circuit it appears it is pretty much the reference implementation of the TDA8920 circuit, with a volume control tacked on. Though the PCB mentions 0.680uF caps, they have used values 0.470 as per the reference circuit
Some minor tweaks I have made to the unit include:
- remove the input capacitors, and put the inputs where the capacitors were. This cuts out the 0.47 coupling caps, the volume control, and some 5.6K resistors. Also means I have to make sure anything I plug into it doesn't have any DC offset! This has really cleared up the amps sound quality a lot.
- took the 10000uF caps from the connex amp and wired them in parallel with the existing 4700uF caps. Seems to have more solid bass... but hard to say.
- took the 11uH inductors from the Connex amp and replaced the 33uH inductors (which are in metal cans). After comparing the circuits and discussing with Col also replaced the 0.470 caps output filter caps with 2 in parallel (0.95uF) to match the values as per the Connex amp. Hard to tell if this helped either.
The overall result now sounds better. Not incredible but quite OK for a modded cheapy. Interestingly this unit doesn't seem to have what I call the "Diana Krall" bug (faint fizz audible on very soft piano notes) thats been noted on other TDA8920 based modules. I'm using a basic plastic enclosure from Altronics, 160VA toroidal transformer, and have the ESP groundloop protection in there as well.
Last edited:
In what way does it sound "cleared up"?
Is the input differential? Split supply with one input tied directly to ground and the other directly to signal?
Do you happen to know why it doesn't?
When I first fired up the amp it just sounded a bit "grainy", though not in an unpleasant way. It just sounded clearer I think.. though this could be my perception bias of course after investing the effort fiddling with it.
Inputs are differential (can be tied together BTL?)
I didnt trace the whole circuit, but the parts I did trace indicated to me it is pretty close to the reference circuit as per : http://www.eurica.ru/sound/TDA8920TH.pdf
No.
also.. a few weeks ago I killed it.. sent a blast of full amplitude noise into it while fiddling with a pre-amp and fried the TDA8920 chip. Although I could attribute removing the input capacitors, I did have it buffered via a behringer Xenyx1204 mixer.
re-using the case for an AMT2050 board, as the toroid is the right voltage.
Yeah, these chips seem to fry easily. From what I know, the PROT cap on pin 13 determines the trade-off between short circuit protection and audio drop-outs at high volumes.
Hi,
yes the heat sink is pretty small, though it didnt get much hotter when I was using it, but then I didnt crank it that much (or bridge it). It did have pads on the board for soldering thr bridges in.
The ConnexElectronics units run a lot cooler, and have a lot more options, and are smaller.. though cost a few bucks more - and harder to mount, depending on your case layout.
yes the heat sink is pretty small, though it didnt get much hotter when I was using it, but then I didnt crank it that much (or bridge it). It did have pads on the board for soldering thr bridges in.
The ConnexElectronics units run a lot cooler, and have a lot more options, and are smaller.. though cost a few bucks more - and harder to mount, depending on your case layout.
Thanks, I'll think I'll check out the ConnexElectronics modules, I don't mind spending a little more really. I'm tempted to check one of these board out though, mainly out of curiosity really, if I don't use it for the subwoofer I have plenty of other uses for it.
i also have another question if i have a 20V DC current (instead of AC) can you tell me which components to bypass in order to make it work? I tried to connect the 20V DC in the circuit after the rectifier GBU808(in my pcb), but the only sound i can get is a small "CH" when I connect the line in. Thank you.
if i have a 20V DC current (instead of AC) can you tell me which components to bypass in order to make it work? I tried to connect the 20V DC in the circuit after the rectifier GBU808(in my pcb), but the only sound i can get is a small "CH" when I connect the line in. Thank you.Hi.
I bought the same amp on ebay for a portable soundsystem that needed a new amp.
Unfortunately im a newb in this field and cant get more than some very small hums out of it.
Im most confused about the powersuply as im using 12v batterys to power it and I don't really know how to connect the power to the amp.... It says ac2x20v(se attachment).... How do i connect it when im using 12 v batterys????
sorry for being a newb
I bought the same amp on ebay for a portable soundsystem that needed a new amp.
Unfortunately im a newb in this field and cant get more than some very small hums out of it.
Im most confused about the powersuply as im using 12v batterys to power it and I don't really know how to connect the power to the amp.... It says ac2x20v(se attachment).... How do i connect it when im using 12 v batterys????
sorry for being a newb
Attachments
hello i just bought same model as you have and i want to ask about capacitators because i think 4700uF is not enought for good bass i tryed to add 2200uF 35V from ELNA and its better now.
where is limit for PSU caps?
i have 50W 6ohm reproductors from old sony tower and 240V - 20VAC-0-20VAC transformer as power source
where is limit for PSU caps?
i have 50W 6ohm reproductors from old sony tower and 240V - 20VAC-0-20VAC transformer as power source
Hi,
I reckon this amp have an upgraded TDA8950.
Else will be 2 TDA8920 in BTL mode.
TDA8920BTL 2.0¹¦·Å°å£¨TDA8950Éý¼¶Æ·£©-ÌÔ±¦Íø in Chinese.
I reckon this amp have an upgraded TDA8950.
Else will be 2 TDA8920 in BTL mode.
TDA8920BTL 2.0¹¦·Å°å£¨TDA8950Éý¼¶Æ·£©-ÌÔ±¦Íø in Chinese.
link on ebay is unavailable now. There're a lot of other choices:
TDA8920B 100Wx2 Class-D HiFi Audio Amplifier - Boards | Kits | Components | Modules | Tools
TDA8920B 200Wx2 BTL Class-D HiFi Audio Amplifier - Boards | Kits | Components | Modules | Tools
TDA8920B 100Wx2 Class-D HiFi Audio Amplifier - Boards | Kits | Components | Modules | Tools
TDA8920B 200Wx2 BTL Class-D HiFi Audio Amplifier - Boards | Kits | Components | Modules | Tools
Bypassing the input coupling capacitor did improve the sound, provided you are sure the source doesn't have any DC .. but then I killed my TDA8920 amplifier a playing with a preamp I was assembling after that.. good it wasn't expensive!
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.