Hello there,
Clearly I do not know what I am doing, and I probably shouldn't even be trying to build a Franken Amp from what seems like a mish mash of parts, but here goes,
Main amp board,
E3 Audio TPA3255 2ch PurePath™ Ultra-HD Class D Audio Amplifier
TPA3255-2CH-260W | 3e Audio
Power supply,
Connex Electronic SMPS300RS 300 watt (400 watt peak) 36v, +-12 volt power supply
SMPS300RS | Connex Electronic
Preamp with single ended input,
WEILIANG AUDIO preamplifier board with shield,
WEILIANG AUDIO preamplifier board with shield|breeze audio|lm317 lm337preamplifier audio - AliExpress
Single ended input to balanced converter board,
Unbalanced to Balanced Output Stereo Converter Board Low distortion DRV134PA x2
Unbalanced to Balanced Output Stereo Converter Board Low distortion DRV134PA x2|x2 housing|board to board rf connectorboard msi - AliExpress
It is my understanding that the E3 Audio EAUMT-0260-2-B TPA3255-2CH-260W prefers to be driven with differential input to get the most out of it, that is why I have included the last item.
Perhaps I don't need this last item, and the amp should be driven single ended, what do you think?
Am I barking up the wrong tree here, or does this look like it would work/be a good fit of components?
Thank you,
David
Clearly I do not know what I am doing, and I probably shouldn't even be trying to build a Franken Amp from what seems like a mish mash of parts, but here goes,
Main amp board,
E3 Audio TPA3255 2ch PurePath™ Ultra-HD Class D Audio Amplifier
TPA3255-2CH-260W | 3e Audio
Power supply,
Connex Electronic SMPS300RS 300 watt (400 watt peak) 36v, +-12 volt power supply
SMPS300RS | Connex Electronic
Preamp with single ended input,
WEILIANG AUDIO preamplifier board with shield,
WEILIANG AUDIO preamplifier board with shield|breeze audio|lm317 lm337preamplifier audio - AliExpress
Single ended input to balanced converter board,
Unbalanced to Balanced Output Stereo Converter Board Low distortion DRV134PA x2
Unbalanced to Balanced Output Stereo Converter Board Low distortion DRV134PA x2|x2 housing|board to board rf connectorboard msi - AliExpress
It is my understanding that the E3 Audio EAUMT-0260-2-B TPA3255-2CH-260W prefers to be driven with differential input to get the most out of it, that is why I have included the last item.
Perhaps I don't need this last item, and the amp should be driven single ended, what do you think?
Am I barking up the wrong tree here, or does this look like it would work/be a good fit of components?
Thank you,
David
Attachments
None of us knew what we were doing at first. We all made mistakes and blew things up but after learning
not to make those mistakes, I very rarely damage anything anymore. My last little preamp project went from
schematic to PCB, no simulation or breadboarding. It works well.
In my opinion you have an elementary integrated amp without tone controls or input switching but unless
you make some serious blunders, it will likely work quite well. The 36V supply will limit you to about 80 Watts
at 8 ohms, 160 at 4 ohms per channel. One thing to beware of is the DC output of the amps will be about 18V
(power supply / 2) relative to ground. The speaker will see 18-18V across it and will be fine but DO NOT ATTEMP
to drive a speaker relative to ground. It will cause smoke. Yes, you could put output caps to block the DC but they
will simply increase the cost and space and will NOT improve the audio in any way. In mine I simply left them out
and it's been fine for 2 years.
Good luck, you're off to a good start
G²
not to make those mistakes, I very rarely damage anything anymore. My last little preamp project went from
schematic to PCB, no simulation or breadboarding. It works well.
In my opinion you have an elementary integrated amp without tone controls or input switching but unless
you make some serious blunders, it will likely work quite well. The 36V supply will limit you to about 80 Watts
at 8 ohms, 160 at 4 ohms per channel. One thing to beware of is the DC output of the amps will be about 18V
(power supply / 2) relative to ground. The speaker will see 18-18V across it and will be fine but DO NOT ATTEMP
to drive a speaker relative to ground. It will cause smoke. Yes, you could put output caps to block the DC but they
will simply increase the cost and space and will NOT improve the audio in any way. In mine I simply left them out
and it's been fine for 2 years.
Good luck, you're off to a good start
G²
The input of stage of the e3 module already includes op-amps to do single ended to balanced conversion, there is nothing to be gained by doing this is on an external board.
Only if you had a super high quality source that had a balanced output would there be any benefit to use that input mode of the amp module.
Only if you had a super high quality source that had a balanced output would there be any benefit to use that input mode of the amp module.
>>>The input of stage of the e3 module already includes op-amps to do single ended to balanced conversion...
You think this would be worth mentioning in the documentation. 🙂
When I found some high rez photos of the board and zoomed in, I saw the jumper for the SE - DIFF setting, Thank you!
You think this would be worth mentioning in the documentation. 🙂
When I found some high rez photos of the board and zoomed in, I saw the jumper for the SE - DIFF setting, Thank you!
Attachments
I have the new version of the amp with the thru-the-hole caps and the op-amps that can be easily swapped. I’m using the 3e 36V SMPS driving 8 ohm speakers. Sounds superb with just SE input and output. I have a DAC supplying a pre-amp used for volume & balance control. I can remove the pre-amp if I drive the digital signal to the DAC from the USB C output of an old cellphone (has a volume control; music streaming) directly into the amp.
Yes, and worse, the 3e-audio board allows you to configure its input circuit for differential mode - but you cannot bypass these onboard opamps. So even if you chose to use an external SE-differential converter, its balanced outputs would still pass through the onboard op-amps, meaning that you would be adding additional electronics to your signal chain, unnecessarily.
It's my opinion that opamps at the input of TPA325x amps add too much "sizzle" for my liking, so having additional opamps in the chain can only make things worse.
Similarly, that preamp board will add additional opamps to your signal chain. The input stage of the 3e-audio board (and other TPA325x amps) is often described as "SE-differential converter" but it's also effectively a preamp. For volume control all you should need to add is a potentiometer.
Or one step better, in my opinion, is to use a DAC with software-manged attenuation, then just run the TPA325x at full gain, as a true power amp.
@Dave,
Connex SMPS has Dual DC +/-12V as auxillary.
But the WEILIANG Preamp needs Dual AC (Transformer out) as input? how you plan to connect?
any idea how much mA current the Preamp board uses?
I am also in same boat as you. Sorry to Hijack your thread!
Any advice will be welcome.
Connex SMPS has Dual DC +/-12V as auxillary.
But the WEILIANG Preamp needs Dual AC (Transformer out) as input? how you plan to connect?
any idea how much mA current the Preamp board uses?
I am also in same boat as you. Sorry to Hijack your thread!
Any advice will be welcome.
Linuxfan, the input op-amp are socketed so there is nothing to stop you simply removing the opamps and driving your input signal straight into the output pin of the socket.
To me the design as it stands today is a perfect compromise between a board that is straightforward for less experienced user, whole still giving plenty of options for tweeking options for those with skills.
Btw. On the bottom of the board under the DIL sockets are footprints to fit SMD opamps...what more could you want?
To me the design as it stands today is a perfect compromise between a board that is straightforward for less experienced user, whole still giving plenty of options for tweeking options for those with skills.
Btw. On the bottom of the board under the DIL sockets are footprints to fit SMD opamps...what more could you want?
Indeed. And that's exactly what I did with my 3e-audio amp board - the old version - by soldering wires onto the board -
https://www.diyaudio.com/forums/class-d/309813-wrong-tpa3255-97.html#post6113031
But I'm fairly sure the 2 people in this forum thread who are considering the addition of a preamp board are not also intending to follow such a process.
My take-home message is that if you want to add volume control to your 3e-audio amp, there's no need to add a preamp board - because the 3e amp already includes an onboard preamp.
All you need is a potentiometer.
Thank you for your replies.
Can you tell me more about the amp you built here,
https://www.diyaudio.com/forums/class-d/309813-wrong-tpa3255-97.html#post6113031
What else is in there besides the PS and 3e board?
David.
- a good quality external regulator for the amp's 12V rail -
LT3045-78XX Ultra Low Noise LDO Voltage Regulator
In hindsight I'm not sure this made much of a difference.
- and a cap multiplier -
Capacitance Multiplier
I was intending to add this at the output of the Connex SMPS, to see if I could hear any improvement, but with all the other fixes and modifications, I never got round to it.
The biggest improvement to this amp was bypassing the SE-to-differential input stage - of course for this you need a playback device with differential outputs.
It used to be the case that such DAC's were uncommon, and expensive, but just recently there are 3 commercially available DAC's with differential output which are quite affordable -
SMSL Sanskrit 10th AK4493 edition, Topping E30, and Soncoz LA-QXD1. Any of these with your 3e-audio opamp-bypassed amp should be a killer combination.
SMPS300RS -
SMPS300RS | Connex Electronic
I ordered it with 32V output, since this is the upper voltage limit that the cap multiplier can handle. If there was no cap multiplier to consider, I would have ordered 36V.
Bear in mind that my amp was the TPA3251 version. For the TPA3255 version you should go for 48V, and possibly the next model up the Connex single-output range, the SMPS600RS -
SMPS600RS | Connex Electronic
SMPS300RS | Connex Electronic
I ordered it with 32V output, since this is the upper voltage limit that the cap multiplier can handle. If there was no cap multiplier to consider, I would have ordered 36V.
Bear in mind that my amp was the TPA3251 version. For the TPA3255 version you should go for 48V, and possibly the next model up the Connex single-output range, the SMPS600RS -
SMPS600RS | Connex Electronic
What do you think of this power supply?
Nobsound Hi Fi 400W Switching Power Supply (SMPS) 48V/8.3A with PFC for Digital Power Amplifier|Amplifier| - AliExpress
Any pictures of your finished build?
What power supply did you use?
Thank you,
David.
I'm suspicious of the quality. And it doesn't include resonant LLC technology. Having said that, modern class D amps seem to be unfussed about less than ideal SMPS's, so it might sound just fine ...
but I really consider it a mismatch. For a bargain TPA3255 amp, sure, use a bargain SMPS. But for a 3e-audio amp, get something better. The difference is only $40 or so.
It is possible to get a "bargain" resonant LLC power supply -
LLC resonant soft switching power supply power amplifier 600W +/ 55V voltage regulator output|dvd honda|accessories flowerdvd add - AliExpress
But again, you only save a few dollars. I would get the reputable Connex.
Actually, I asked the same question in TPA3255 thread also, but haven't got clear cut suggestion.
Thanks Linuxfan for the advice.
@Dave/Linuxfan,
Can you please share ur opinion about this PSU? Single 48V?
500W HIFI Amplifier Switch LLC Soft Switch High Power Supply Single DC Output 24V 36V 48V 60V 70V 80V Replace RingCow H133|Amplifier| - AliExpress
I'm fine getting the Connex, I have seen it recommended in other threads for other amps.
What would the difference be between say,
SMPS300RS 38V 110V power supply
SMPS300RS 48V 110V power supply
SMPS600RS 48V 110V Power supply
Is it possible to buy too big a power supply?
Thank you,
David.
No. Your amplifier (and most other electronic devices) draws only the current it needs/demands.
If your power supply has a current rating higher than what your amplifier requires, that's a good thing - it gives you additional headroom, and means that the power supply will never be operating near its upper current limits.
Hello, I am preparing a 3e Tpa3255 build. Are you sure the SMSL and Topping have differential output? They only have RCA output. Can they do differential output through RCA?
I was looking at xlr out dacs with volume control, remote and, maybe, a rotary knob. On my shortlist are Topping dx7, dx7s, which are rather expensive at around 400 usd and SMSL M200 250 usd. I am waiting for the launch of SMSL su-9 to make my decision.
I have ordered the Nobsound power supply, mainly because it has PFC and the heatsink offers some shielding. I may be able to give some uninformed feedback once it arrives.
Since the op amps are socketed, can't we just short same pins on the socket to remove the op amps?