How to build yourself a Warm+Tube-Like 2x120W Power Amp for dirt cheap.

vultures

vultures

Well-known member
So you want to have Warm+Tube-like Tone? It can be in your hands for under.. $60+/-


I had a friend talk me up on this Kruse power amp. He sent me the pedalboard version of the power amp. He bought two of them brand new. I got curious. What made this relatively unknown amp builders stuff just that good? What's the secret sauce? What do these sweet sweet guts look like? Well I'm surprised and I'm sure you will be too.

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The first sign of serious engineering was EPOXIED SCREWS. How delightful. There must be some unbelievably advanced circuitry going on inside. What else would possess a mortal man to seal this wizardry behind sullied screws?
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Here lies the bounty. THE GUTS. The.. What is this? What could these symbols on this board possibly mean? WX-DC2416? If only there was a Rosetta Stone of amp building to guide me to this mysterious tech. Oh. I can just punch that in on Amazon or Ali-Express. Also the first result for "Dual Channel Power Amp Board" on Amazon directs right to this thing.

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My favorite part is having a hard wired 3 prong power cable with absolutely no grounding.

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Anyway, all funny business aside. I normally would have just thrown this in the trash and been on my way.. But plugging something into my cabinets and into my walls with a floating ground rubs me the wrong way. Along with a lot of these screw on connections are loose. I told my buddy to ask for a refund, but he doesn't want a confrontation. I asked him to take a look inside his. His screws are also epoxied and he isn't able to get it open. These also started showing up with this sticker on the bottom.

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Anyway, I was always taught to leave something better than I found it. Grounded it to the enclosure. Replaced the hard wire cable for an IEC port. Replaced some of the wires. Swapped the jacks so that the Left Input/Output were on the LEFT side and the Right Input/Output were on the RIGHT side. Is it safe? Maybe. Will I use it again? Sure, plugged into a power conditioner. I'm going to send this back to my buddy and have him send me the one he can't open.

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So let's get into how much it would cost you to build this yourself.

WX-DC2416 - Power Supply Board:
XH-M543 / TPA3116D2 - Dual Channel Power Amp
Alpha A10K Potentiometers
Latching Power Switch - 12-24V
Insulated Stereo Jacks
IEC Port
Knobs?
  • Whatever, man. I don't tell another dude what to do with his knobs. Pick your own.
Enclosure - Hammond 1550G
Rackmount Enclosure Option(s)

So you can build yourself one of these tube-like power amps for around $52.67 +/-. Good luck. Happy building.



Also a FYI, I found a site that thoroughly reviewed the power amp board. According to the datasheet this chip is only rated for 2 x 50W at 4Ω. Which means half that at 8Ω and half that again at 16Ω.

Link to the review:
https://smartpuls.ru/diy/tpa3116d2-1/amplifier-tpa3116d2-en.shtml

Link to datasheet:
https://smartpuls.ru/diy/tpa3116d2-1/tpa3116d2.pdf
 
Aside from the crazy markup, that missing ground seems super sketchy. What would be the reason to do that? :confused:
 
Jinkies!

I believe that the 2x120w rating comes from using a 24v power source in a very specific scenario and 2x50w is when using 12v. That said, the PSU in that thing is rated at only 220w, but I'm guessing even that's a typo and is actually closer to 150w and the 220w is probably from the the wall which would indicate that it is terribly inefficent (under 70%) and probably only has just enough lifespan to sneak a warranty onto it for a heavy user. 🤷‍♀️ The voltage regulation mirroring and wiring seems to indicate the design is likely two separate chips in two separate sockets instead of both silicon on the same package. Probably allowing a higher TDP vs the latter.

Thanks for putting lipstick on that pig! Definitely poor/possibly dangerous assembly. Cool that you made it safe, at least. That company should be ashamed of themselves, tbh.
 
Erock said:
Aside from the crazy markup, that missing ground seems super sketchy. What would be the reason to do that? :confused:
Click to expand...

Guessing from the power cord side it was suppose to be connected to the nut perhaps to ground it or wedge to the chassis if that piece is plastic, but there is no factory grounding for either the psu or amp boards, either. No standoffs, just what I'm assuming is velcro. Junk, poorly engineered or even maliciously built to fail, possibly.
 
Yeah, that ground is quite sketchy.

Building poweramps with these little Class D amps has become pretty common. I have thought many times about grabbing a few of the ICEPower modules and using one of these cases from here: https://www.ghentaudio.com/
 
For anyone interested in a decent MOSfet power amp, I recently picked up a used Avantone CLA-100 which has much better build quality than the Kruse for about the same price. It's got a toroidal transformer and takes only a single rack space.
It's very loud into stereo 8 ohm 4x12 cabs and sounds great. Convection cooled for silent performance as well.

https://avantonepro.com/en/products/cla-100
 
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chumbucket said:
For anyone interested in a decent MOSfet power amp, I recently picked up a used Avantone CLA-100 which has much better build quality than the Kruse for about the same price. It's got toroidal transformers and takes only a single rack space.
It's very loud into stereo 8 ohm 4x12 cabs and sounds great. Convection cooled for silent performance as well.

https://avantonepro.com/en/products/cla-100
Click to expand...
Heard these are killer. I believe this is the stuff Dave Friedman is recommending these days, too?
 
Shask said:
Yeah, that ground is quite sketchy.

Building poweramps with these little Class D amps has become pretty common. I have thought many times about grabbing a few of the ICEPower modules and using one of these cases from here: https://www.ghentaudio.com/
Click to expand...
I haven't heard any of the new high end Class D stuff but the lower end stuff like the Seymour Duncan power amps don't hold a candle to MOSfet in my opinion. The difference is really noticable when you crank up loud. The Class D stuff is fine at low volumes but the high frequencies get weird as you turn up.
 
In your first image there is a Kruse logo on it. Was that just stuck there or was that actually built and sold by Kruse?
 
Pretty positive this is a legit Kruse. I had a correction from my friend. The unit I have, he bought used. The unit with the warning label on the bottom he bought new. Given that the screws on both of them are expoxied in the same exact manner.. I can confidently say they are built by Kruse. Nobody opened this unit, swapped in cheap chinese parts, got new black screws and expoxied them in just to sell it. I've had this up on Reverb for $150 after I fixed it to try to get my buddy ANY of his money back, but nobody wants this piece of shit.

I pulled the listing. I keep getting asked pointed questions about what wattage at what ohms and I just can't bullshit people. I know this outputs 50W MAX at 4 Ohms. I don't feel right selling this as a "120W Stereo Power Amp" when it doesn't even meet half that. Hoping nobody here wastes their money.
 
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