DIY Amp for my Home Theater

[fredsal2]

I built a 3 channel AKSA-100 amp for use in my home theater (as well as for 2-channel music). I had no serious problems, other than the challenge of fitting everything into some unique dimensions. It behaves wonderfully.

[jgwinner]

I'm actually building 6 1 channel OPTI-MOS's from Seal Electronics

However, I think the cost of doing this is actually higher than just buying a semi-decent receiver, but then again this should sound better.

[RichardH]

[Not sure if this ought to be new thread, but it's related, so here goes....]

I've been considering something similar, except just for 4 surround channels - I already have a decent power amp for front duty. I'd thought about doing it as a two box solution - power supply in one, amps in another. As this would be a first project, and I don't have a means of producing PCBs, I was intending to use a kit based on the LM1875 which would give me around 25W per channel (+-25V supply). I then got a bit more ambitious, and have started considering a similar kit using the TDA7294 (50W, +-30V supply) to give me a bit more juice, and also mute and standby "out of the box".

My main uncertainty is regarding power supply. I'd like to keep the cost down, so sharing a transformer seems the way forward. Here are a few things I'd like to be confirmed/corrected

1: If I run more amps off one transformer, I need a greater VA rating, but would keep the same voltage output. I should be careful to check what the output of the transformer is UNDER LOAD, as that's what it will deliver in the real world - either that, or I need a slightly higher rated transformer. (Suggestions for what VA rating for the above amps would be appreciated).
2: It's best to have seperate Bridge Rectifiers and Capacitors for each channel on the power supply, although this will up the cost a fair bit. Is if feasible to use the same set to power all channels, or will this degrade things too much?
3: Should I worry about speaker protection circuits, as again this will add to the cost.

Thanks all

[BrianGT]

Originally posted by ccarrigan
I am looking at building an amp for my HT. I have looked and searched this forum and come up with this thread

6ch amp help ?

which deals with the 6 channel 300W amp for the aussie site. But I believe it has said "coming soon" for a while. Does anyone know when it will be available? Are there any other solutions that are fairly straight-forward? I am thinking roughly 150wpc and 5-7 channels. I am new at this but have done some DIY in the past and feel comfortable that I can do anything I put my mind to.

Thanks for your help.

Craig Carrigan

I was actually working on a 6 channel leach amp in a single chassis. I would use two 650VA transformers for this. I put this aside, as with my new Thor TL speakers, I don't need more then 60W per channel. I have a leach amp design that minimizes wiring, if you want the gerber files. I am thinking of getting a board order done in january or febuary, after I finish all of my aleph projects and start on getting a home theater setup going.

Here is a picture of my pcb. Like the P3A (which is great if you need less power), it easily mounts on one heatsink with minimal wiring. It appears to be working now from my testing, and I will soon compare it to a channel of the old design on some measurement equipment. I just have been set back by the ideas of the pass labs designs, making me want to get a good 2 channel setup first with my thor tl speakers, then worry about a ht setup for my other room.

Here is a picture of my leach amp pcb:

More pictures (and hi-rez) at:
http://brian.darg.net/leachamppcb

--
Brian

[BrianGT]

Compare this to my original leach amp wiring as Austin mentioned earlier:

Also, I am getting together a 6 channel PGA2310 digital volume control for the large amp, for when I decide to build it.

I am also working on a version of the leach superamp with integrated devices, should you desire 240W+ power into 8 ohms. I am just building it for driving a subwoofer at 500W+

--
Brian

[jgwinner]

Brian:

Geez, I got one of those 2kw Brigar electronics transformers. I'm going to be able to run the THor's with 200w/channel. That sounds dangerous

I like your heatsinks! Where did you get most of them?

[BrianGT]

John,

which heatsinks?

How are the Thor TL speakers going?

--
Brian

[jgwinner]

*doh*

Sorry, guess it was a non-sequiter [sp?] I'd followed the link to your photo album and wandered around.

I liked your Aleph heatsinks and the ones on your 'other amplifers; specifically Jen's looked prett nice too.

After looking at your 2nd picture above I think that heatsink wouldn't work well for my Opti-MOS, although that one looks pretty nice too.

I have a hard time finding good heatsinks mail order, although I admit I've never called a distributor, I'm usually too busy in the day to do that.

The Thor's are gluing now .. I routed out the speaker holes and have the flat wire mounted. Gorilla glue is great stuff!

[BrianGT]

Originally posted by jgwinner
I liked your Aleph heatsinks and the ones on your 'other amplifers; specifically Jen's looked prett nice too.

The heatsinks that I have for my aleph chassis, I picked up surplus from a company north of atlanta. They only had a few. I picked up 8 of them for $24 each. Here is the aavid profile for them. They are all 8" extrusions of this:
http://www.aavidthermalloy.com/bin/e...8&airflow=57.2

I am thinking of ordering the next heatsinks from mmmetals.com next time, as I can't find anymore large heatsinks. Several people have had good luck with them.

I do like how the chassis has come out so far. I am putting a wooden front on the chassis, matching my speakers.

Good luck with your Thor TL speakers. How are you going to finish them?

--
Brian

[jgwinner]

How are you going to finish them?

By finally getting my A** in gear

I'm routing a radius around the front and back sides, and planning on wrapping a thin Walnut laminate around it. I found 36" and 24", so I'll be using two pieces of 24". This wil make a seam, which I'll locate on the side of the speakers and hide with a trim piece.

That's the plan now anyway. The whole family gets here on Tuesday, I have a bad feeling the finish will be MDF especially considering that Rockler only had ONE 24x96 sheet of Walnut.