ConnexElectronics TA3020 V3c amplifier module.. built into a ugly but functional steel case.

I recently ordered one of these modules after being very impressed with the sound of an earlier version of this module I borrowed from Col. It’s an amp module using the Tripath TA3020 IC, which can do up to 110W at 8Ω, with max. 0.1% THD, though I’m more interested in the 50W per channel it can do with just 0.02% THD.

This version of the module has a built in bridge rectifier and power capacitors, it just needs AC power.

I ordered it with the dual 18,000 uF Elna caps option, no fan.

The choice of MOS-FETs was added to the page after I ordered, so I guess I got the default.

Being eager to just Get The Thing Up And Running Right Now I have quickly cased it up using an discarded steel power supply case I found in a recycling bin a while back. Luckily this steel case already had all the grounding points, and a medical grade EMI filter as well, so I already have the starting point for an OK build. It’s actually nearly the perfect size for this project, and I repurposed some of the existing holes in the chassis so I didnt have to cut new ones.

As well as the amp module itself I got a soft start module from the same vendor as it is recommended as I’m using a 500VA toroidal transformer, to avoid zapping things when I turn the unit on.

I’ve chosen the 35v-0-35v 500VA transformer as I’ve been told 35v is about the maximum I can drive a TA3020 before it needs a fan to cool it, and I just want to use the heatsink it ships with.

I’ve implemented the ground loop protection as per the Elliot Sound Products article (thats the diode bridge in the middle).

Just using 600V 14AMP cable to connect the speaker outputs, which are poking through unused fuse holes on the box affixed to a bit of masonite for to insulate them from the chassis.

Luckily a phenolic RCA dual socket I had lying around from a long abandoned project fitted one of the DC holes with the screw holes even matching up, as I dont have the tools to cut the steel case.

outside of the case (before I cleaned it and stuck the rubber feet on):

the sound
Ok the case is a bit rough around the edges, but I confident it’s wired properly and safe enough to sit down and have a listen – I tried it first with a CD walkman and some crap Tandy minimus speakers and it worked first go and no smoke escaped… so out to my “cheapowave” Econowave speakers, being driven by an AlienDAC DAC into an Elliot Sound Products p88b preamp.

It sounds GREAT.. really firm, powerful bass, while keeping high end space and detail. A little bit more volume and possibly bass definition than the older TA3020 module (but I am feeding it more voltage via a much larger VA rated transformer).. and heaps more bass and detail than my ART SLA-1 100W RMS Class AB power amp.

Almost dead silent, some white noisy hiss audible if I put my ears right up to the horn of the econowaves, but nothing at normal listening distance. Note I suspect the ART SLA-1 is a bit quieter.

A bit later I spruced up the build a bit, after initial testing showed it to be OK:

  • added gold plated rca sockets
  • illuminated on/off switch (12v switch controlling the soft start module)
  • bolted the ground loop breaker and toroidal transformer to the chassis after drilling holes for them.
  • snipped the simple header wires provided and soldered in some shielded audio cable instead.
  • drilled some holes and mounted the two PCBs with m3 nuts and bolts and nylon spacers. The first attempt caused some ground loop hum, but replacing the metal nuts and bolts with polycarbonate ones from Altronics fixed that issue. Cristi from Connex says “the amplifier mounting holes are isolated from GND except the middle one between the inductors, and that can be used as the GND star point“.
  • Some rubber feet.

still a pretty spartan hacky functional build.. but soundwise definately up to scratch.

Note: this an edited version of some posts to AudioKarma forums..

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