Maybe I should clarify.

I have been using this radio shack 30W PA head (which I am sure is less efficient than a modern design) driving a couple of home made cabinets with dept store announcement speakers and car audio speakers (all thrifted) for about 1 year for live shows. It works, but it gets distorted at the levels I use it. I don't play super loud.

By PA I mean that I mix a couple of synths, a guitar, and a seldom used mic into one amp.

I'm going to see how this amp works. I can always add more in some way or another. Maybe I can use it alongside my rat shack PA.

This isn't to mix drums, amps and a full band of mics through. Maybe think of it more like a "keyboard amp."

Quote from: joecool85 on June 01, 2011, 09:10:30 AM
I would go with the 25-0-25 100VA one that JP linked to.  For $18 you can't beat it and you would get full output from your chip.  At full bore it would be maxed out, but trust me, you will rarely if ever be full bore on it assuming you have a decent speaker hooked up - it is LOUD!

I ordered that one last night. I hope it is loud.

I am planning to use the amp for my portable pa system for my live setup. Currently I am using a 30W rat shack PA head from the 70's and it is not cutting it.

Sorry for my absence/lag in response... I am getting back to this project.

So there has been links to transformers in this thread that are rated 160VA and 100VA. What does that rating mean?

At 100VA, will I not be able to get the full potential output of the chip?

Thanks again for your patience.

Ok thanks both of you for your responses. Haha, I had no idea that it was not a commercially available board. No wonder I was so confused about it.

I have access to a decent electronics surplus store, so I may be able to get the transformer I need. I don't think I will be able to dig up a bipolar DC supply at that high of a voltage, or at least I haven't seen one so far.

So I am sorry because I am really ignorant when it comes to transformers.

If you could give me as much detail about the type I should be looking for - I am a little confused, for example about what 22v+22v means? Is that for the output of the transformer? Would that be two outputs that are out of phase with eachother?

Or if you could point me to a commercially available transformer that meets the necessary specs, so that I can look them over and compare them to one I can buy locally?

Thanks so much again.

Hi Everyone,

I was the lucky winner of the most interesting amp enclosure contest. I most graciously received the 3886 amp in the mail a couple weeks back and am ready to finish up this project - I am working it into a self-contained live rig.

I've built several SS amps before, but always used a thrifted DC power supply of one sort or another. I have no idea about making a power supply.

Honestly, I've been looking at chipamp.com and I am a little confused about which amp I even have. I believe it is the 3886 mono kit - though I think the PCB is different than what he shows there as it looks like on mine the power supply is included on the board (other than transformer), and on the site it shows them being seperate boards. There is no pic of just the 3886 mono kit though, and the PDF manual for building is confusing to me, again because the boards shown there all look different from mine.

SO all that out of the way - my questions:

1. How do I know what to look for in a transformer? As mentioned before, I have never built an AC->DC power supply and don't really know much about transformers in general. I read the choosing a transformer section of the PDF manual and it was largely greek to me...

2. If I found a suitable DC power supply, could I just use that and connect it into the power inputs on the board?

3. If this is possible and I were to look for a pre-made DC supply, could it be single rail, and what type of voltage and amperage output ratings would I be looking for? I have a knack for finding things at thrift stores. Also, if so which connections would go where AC1, AC2, gnd...?


FYI, my hope is for it to be "as loud as possible" so that is what I have in mind when looking for the above components.


Thanks

Quote from: dmartn149 on March 06, 2011, 12:20:31 AM
TopTop, That's really cool! I figured you would have something for this contest.

Thanks...

Also, HI EVERYBODY!

My entry

Old Art Deco Space Heater made into a small 2 output channel SS chip amp.

Uses TDA2005 Stereo chip, custom designed tone shaping preamp based around a cmos 4069UBE hex inverter and custom voiced for the speaker. Germanium limiting diodes between the preamp and power amp sections. Has built in speaker and external speaker output for the second channel.

It is a very clean "chimey" sounding amp.

Uses a vintage radio shack 6x9 speaker which is mounted to the inside with a custom fit/cut wood panel covered in thin dark blue cotton fabric.

I kept the original heat knob (used for volume) and power indicator glass, grill cover (what a sweet looking pattern), and paint. Drilled holes for input, speaker ouput, and power switch. Did a little work to keep rattles down. The steel enclosure actually is surprisingly tight and does not sound like a speaker in a metal garbage can, as you might expect.  :duh