Amp board - seeking options

[tpremo55]

I've long wanted to build my own amp but have never made it a priority. I've saved this transformer from a landfill and am looking for options and recommendations. With a pair of 13v secondaries, it's not going to power anything big, but how big can I go? Looks like I can do the 2x8w with the TI TPA3110 chip.

Goal is to simply to build a cool little amp that sounds good. If it sounds good enough, I may power a pair of efficient speakers in my office.

Thoughts?

Thanks!

[edlafontaine]

Re: Amp board - seeking options

What you have is best suited to powering a pre-amp, maybe with active x-overs. It has the potential to be the heart of a fun project.

I see ~ 60 VA capacity by the numbers on it. I see you understand the limitations. I think you need more voltage and current for an amp.

If you really want to build an amp you can buy 350VA @ 70VCT from Fair Radio Sales for $12.95. Look for item #401-21

https://www.fairradio.com/catalog.php?mode=view&categoryid=1546

With a couple of SymAsym boards you would have 2 x 100 w/ch @ 8 ohm. Excellent amp, good documentation for the beginner. Post back for links if you are interested.

[tpremo55]

What you have is best suited to powering a pre-amp, maybe with active x-overs. It has the potential to be the heart of a fun project.

I see ~ 60 VA capacity by the numbers on it. I see you understand the limitations. I think you need more voltage and current for an amp.

If you really want to build an amp you can buy 350VA @ 70VCT from Fair Radio Sales for $12.95. Look for item #401-21

https://www.fairradio.com/catalog.php?mode=view&categoryid=1546

With a couple of SymAsym boards you would have 2 x 100 w/ch @ 8 ohm. Excellent amp, good documentation for the beginner. Post back for links if you are interested.

Thanks Ed.
Yes, please post or send the links as I'd be interested in reading them.

I've got an old Optonica integrated amp with a blown amp chip or two. Had it in a shop many years ago and they did not fix it (said replacement chips were very hard to come by, were $$$ and I was in college.

It's been relegated to pre-amp duty, but is a well crafted piece of equipment. Maybe I should revisit repair or pull it apart for chassis and parts such as that nice power supply. Rated at 70wch.

[edlafontaine]

Re: Amp board - seeking options

The Optonica is a neat amp. I agree the output chips may be difficult to find. I think you'll need a schematic before deciding whether to scrap or rebuild.

I have posted an inquiry to AAK asking about SymAsym board availability. I'll pass on the news.

http://www.diyaudio.com/forums/solid-state/175216-symasym-sequel-aaks-rev_1-4-pcb-builders-thread.html

I misspoke earlier. A single board includes 2 channels and integrated power supply...just hook up the tranny.

[tpremo55]

Ed, have you built this amp before?

One question I have is how does the sound compare to the mid-level amps and receivers of yesterday? Can such a project exceed the sound quality of readily available used equipment for the same investment?

[edlafontaine]

Re: Amp board - seeking options

I am still waiting to hear back from Al about board availability.

I built it. All the components are through-hole. I am listening to it now. It is in my 1st choice music chain. There are testimonials and measurements for this amp over on DIYAudio. I have Denon receivers in 2 other locations in my home.

[AJ]

Re: Amp board - seeking options

I misspoke earlier. A single board includes 2 channels and integrated power supply...just hook up the tranny.

I think you have a typo there. A single AAK board is one channel, with it's own power supply. Ideally, you would have two transformers (for a dual mono build) or one transformer with two center tapped secondaries (hard to find).

[edlafontaine]

Re: Amp board - seeking options

AJ is right. :o Thanks for the correction. One of the transformers I linked to will power 2 channels

[tpremo55]

Thanks guys. Ed, I did see your posts over on the other forum.

[tpremo55]

Btw, I did dig up the schematic for the Optonica, but don't have component values listed. Of course, I have the amp, so I can get component values if I can read what is there.

I'm not ready to tackle the repair myself, but that should help another shop to review.

Has anyone had experience with Rodd Elliott's MOSFET amp project 101? More info here:
Http:/sound.westhost.com/index.html

How would this compare?

[AJ]

Re: Amp board - seeking options

Btw, I did dig up the schematic for the Optonica, but don't have component values listed. Of course, I have the amp, so I can get component values if I can read what is there.

I'm not ready to tackle the repair myself, but that should help another shop to review.

Has anyone had experience with Rodd Elliott's MOSFET amp project 101? More info here:
Http:/sound.westhost.com/index.html

How would this compare?

The correct link for P101 is: http://sound.westhost.com/project101.htm

The P101 is a very simple amp, and probably sounds very good. However, one could buy a Hafler DH120, P125, or SE120 and have basically the same thing (low power version). The small Haflers can be had for $100-$125 in good shape. Strictly speaking, the small Haflers actually have a better circuit.

I'm not trying to disrespect Rod's work, as I love his website and projects, and wouldn't want to discourage a DIY attempt at a simple lateral mosfet amp... Just be aware a DIY amp will cost much more than the Hafler and probably be no better.

[tpremo55]

Thanks AJ. So are you suggesting that most DIY amps would only provide a result similar to the hafler reference? ...or specifically the P101? Do you have any experience with the AAK amps referenced by Ed?

Do you recommend mods to the older amps like the haflers or others? Any good guidance sites you recommend?

[AJ]

Re: Amp board - seeking options

Thanks AJ. So are you suggesting that most DIY amps would only provide a result similar to the hafler reference? ...or specifically the P101? Do you have any experience with the AAK amps referenced by Ed?

Do you recommend mods to the older amps like the haflers or others? Any good guidance sites you recommend?

Specifically the P101 as it has similar circuitry to the small Haflers and uses the same Hitachi output devices as all of the Haflers. Again, i you like the looks of the P101, go for it.

If the mod is trageted to fix something the manufacturer cheaped out on, or some design issue - great. I have not experience with the AAK version of the symasym but they are well regarded.

diyAudio is great if you can filter through the audiophile nonsense. Bob Cordell has a nice website with some technical info, and a great book. Doug Self has a lot of info on his webpage, and a ton of good books. This website is operated by Bonsai at diyAudio, and has a few good articles. The Leach Low TIM and Double Barrel are classic designs, and there's some good info there. ...just a couple suggestions, as there is tons of info on the web depending on how technical you want to get.

[tpremo55]

Well, a few days ago I found a Adcom GFA-6000 with a guy who was willing to part with it for $100. While this wont kill my interest in a DIY amp, it does distract me for a while again. This Adcom will work well in the theater setup for a while and then may take up a job with Soundeasy doing crossover design as I can now dynamically model 3-way crossovers in stereo. Really clean amp and sounds nice.