amp design help

[blrh93]

hi, i bought a helder hifi tripath ta2020 amplifier a few years back

i managed to make the chip explode as in the photos below

what is the likelihood of the amp working if i replace the chip? or will other components need replacing also?

i have found replacement chips on ebay

TA2020-20 Integrated Circuit from Tripath | eBay

i also need some advice about creating a finished amp with the helder board if i can fix it,

i would like to build an enclosure with a phono pre amp, i have found this kit for sale

United Kingdom ear834 12AX7/ECC83 Tube MM RIAA Phono Amplifier DIY KIT For HiFi | eBay

would this ear834 tube amp pair ok with the helder tripath board? or is it a bit over kill for a cheap tripath amp? if so can anybody recomend a cheaper phono pre amp stage i can pair with the helder amp?

i also require advice about wiring all of this together and other components to use like volume pot and psu for the tripath amp, ideally i would like a phono input going through both amps, an aux input through just the tripath amp and possibly a bluetooth module and also volume control

i will be using the amp to drive a pair of G chang cabinets with pioneer 8" full range drivers

any advice and design ideas you have would be greatly appreciated
Thanks in advance
Ben

 

[djoffe]

Assuming that you're looking for a moving magnet phono preamp without an enclosure, this one has a lot of favorable reviews. You'll need +/-12 supply.

Phono Preamp

It's made for Akitika's PR101 Preamplifier,
PR-101 Stereo Preamplifier

but could be easily integrated into many other pieces of gear.

 

[blrh93]

that looks good thanks, will 20w from the tripath work ok with it?

is it advisable to run the phono pre and amp from separate power supplies?

 

[djoffe]

sure...it should play together nicely...but a lot of what goes on depends upon things like volume controls, and the rest of the signal path.

for supply rails, so long as you have +/-12 to +/-15 Volts, you'll be fine.
Of course, quieter is better, but there are a lot of ways to skin that cat.

 

[blrh93]

i cant find much in the way of 12dc supplies

iFI AUDIO iPOWER | 12V POWER SUPPLY | AUDIOPHILE POWER SUPPLY 12V DC OUTPUT | eBay

i would prefer an internal supply, how do you measure noise? is ~1uV good?

is a toroidal transformer the way to go? do you know of any 12v Power Supply Regulator boards

An externally hosted image should be here but it was not working when we last tested it.

is there a good well know type of pot for volume knob and a rotary switch for input selection? when i look, i just find cheap ones, cant seem to find high quality audio stuff?

i just need a website with all this kind of gear layed out in front of me?

 

[blrh93]

this is roughly what i want to achieve

when you say signalpath, does this involve component layout or just quality of components and connections?

 

[djoffe]

Some comments:

1. I'd probably move input selector and volume POT to the right side. Keep them away from the power supply.

2. What rails does your amp run on? Plus/minus 25? You could use some 3 terminal regulators to generate +/-12 or 15 for the phono preamp. 1 millivolt
of noise or less on each rail should be pretty obtainable.

3. I'd probably swap (on back panel) your outputs to the left, and your inputs toward the right (still aiming for lowest noise).

4. Pots...Lots of people use ALPs...Bourns pots are also quite fine. As to finding parts...I mostly go to Mouser or Digikey (US), but their catalogs are huge and it can be daunting to find stuff. Ebay is another good source for this kind of stuff when buying in small quantities. In the UK, I see many people buying from Farnsworth, but I have not roamed their web site.

5. Since you only have two inputs to select from, you could even use a toggle switch (or push-push-button) DPDT for the selector switch. Depending on your source impedances, you might have a bit of crosstalk between the sources. That could be addressed by a bit more complex switching arrangement.

 

[Fast Eddie D]

How did you blow the tripath up? Since these are so cheap, they hardly seem worth fixing.

People seem to like them, so they must have some virtue. But for a 12 volt power supply, there's bridge amp chips designed for mobile audio that would work great for your application.

I like your speaker idea. Efficient full range in large cabinet can = big sound. This was hi-fi in the 50s. I built some large cabinets with arrays of 8" speakers like yours. The cabinets were huge, and so was the sound. Compared to modern huffy-puffy air suspension speakers, the sound was effortless and dynamic. And loud.

 

[blrh93]

the board was made by helder hifi, who no longer seems to do audio stuff
its alot better quality than some of the Chinese tripath boards, this and the fact they are no longer made, lead me to want to repair it

i think it blew because the power leads got crossed/dodgy temporary wiring
it has just been sitting about for 4-5 year since

thanks for your words about the cabinet design, the anticipation is propelling me to get them built, i priced up the birch ply yesterday at my local supplier

 

[AndrewT]

.................i think it blew because the power leads got crossed/dodgy temporary wiring ...........

I did something similar and too boot broke my own rule of ALWAYS power ON via a Bulb Tester after every modification.
It was working minutes before. I disconnected the three power supply wries from the screw in terminals. I can't remember why, But I do remember that I reconnected the three wires and turned ON.
The chipamp literally blew up.

I had swapped two of the PSU wires around.

 

[Fast Eddie D]

You know how to have fun, Andrew. I haven't blown up a chip amp yet (a miracle) but I did blow up one of those huge power transistors that's the size of a 3886 chip. All it took was one slip of the test lead on the driver transistor and there was a bolt of lightening, a puff of smoke, and the emitter lead was no longer connected to the transistor. The case had a crack and a hole was burned through.

Cook em till they're dead! Fun times.

 

[blrh93]

andrew, do you know a good cheap supplier of 18mm birch ply, im in cumbria so we may be quite close if your just over the border

i have been quoted £67 + vat

 

[AndrewT]

An 8x4 (2440x1220, or 2400x1200) sheet for £67 sounds incredibly cheap for 18mm birch.