Stereo monoblocks - 3255 or irs2092


Paid Member
2018-07-16 10:53 pm
North Notts
I have an interest in building a pair of mono block channels. Maybe just theoretical but I fancy the idea. Just because!
I am thinking seperate trafo>rectifier >smoothing per channel and maybe even in seperate chassis.
I have no specific power requirements and currently use 3255 at 42volts to power modest sized speakers in a modest sized room at near ish field. So I dobt NEED lots of power, but the lower thd and dynamic headroom I like.

I could use 2 x 3e audio 3255 pbtl mono amps. Does the slave/master thing come into play?
Or I could use irs2092.?
3255 will be more expensive to purchase but potentially cheaper single rail psu. Possibly the slave master thing complicates the build?

Or I could build 2 x irs2092. Cheaper boards. More costly dual rail higher voltage psu.

Or would you use a good old LM chip amp?

Thoughts appreciated
With $44 48Vdc 800w SMPS from Aliexpress that’s been measured to be low noise, combined with a good TPA3255, the performance for the price is hard to beat. 3E amp amp is $75 and since you have it already, makes sense to get dual SMPS for two monoblocks.

Better performance is achievable with higher performance 3255 implementations. Especially ones with post filter feedback and good layout and good inductors.

No need to go master slave if monoblocks.

But if you already have large linear power trafo capable of 51Vdc, that works well too. Also let’s you make dual rail PSU for IRS2092 amps which are dirt cheap at $20 for 200w.
I did not measure the ripple out of the SMPS itself but observed that the TPA3255 had a -120dB noise floor with it as the power supply. Moreover, the amp was silent with ear pressed to speaker - consistent with measured -120dB noise floor of amp.

PSU is here (pick 48v 800w):


More info here:
TPA3255 Reference Design Class D Amp GB
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2012-07-20 6:55 am
PSU is here (pick 48v 800w):

More info here:
TPA3255 Reference Design Class D Amp GB[/QUOTE]

Thanks for the link XRK
I checked out the PSU with the specifications you recommended.
Does it have a fan ?

I have a Meanwell 48V 600 watt PSU . It has a noisy fan, which I hve disconnected and use with the top cover removed . So far so good.

I would like to get another PSU. I am glad that you think they measure well and these are cheap!.
Hope they dont come with inbuilt fan.
I too am interested in a pair of mono block class D to drive a par sub woofers to accompany my Nelson Pass amps. I was looking at these as a quick simple cheap fix until I find something that I want to build dedicated for subs only.

Google Shopping – Product not found

Wondom 1x3000w 3kw Class D Audio Amplifier Board -irs2092 Module Mono

Does anyone have any experience with these would they fill the purpose I’m looking for they say they take up to 92 V power.

I would either build my own power supply or purchase one depending on my time available for such a project.
A "reference design" should consider all problems and have the most decent solution´s to the chip´s demands implemented. So if you build an amp module based on such a design, it should match the data sheet´s best data.

In contrast, the "Chinese art of amplifier design" is to leave away any expensive part possible and replace the rest with the cheapest junk that will still work, maybe, for a short period of time. (Also look for "I have no clue about electronic´s, but develop audio stuff for a living".)

xrk971 is designing an amp that he hopes will be even better than the "TI reference" and it seems this might work out well. The TI design is an universal board for trying the chip, not an end user product
3e audio tries the same, while Wondom want´s people to believe that black PCB´s are automatically superior to any other color, while circuit design is irrelevant.
Should answer your question :D;)
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Disabled Account
2010-01-17 9:20 pm
The TI EVM modul is a reference design. I do not like it too much with its bulky caps reverse mounted, but it is hard to beat its performance. It is a universal board to demonstrate all these different settings like 2xSE, 2BTL, 1 PBTL etc so there are many parts and option jumpers on board. For a specific application you can omit the redundant parts yielding a smarter design.
If you want to tweak the THD and noise figure numbers furthermore you may choose bigger inductors and a post-filter feedback - to achieve an improvement in the ballpark of 6~10dB at substantial efforts. I have been there and done that:p
All in all there is nothing wrong with using the EVM for your private HiFi imho.
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