Gainclone for HT

[soundNERD]

I am thinking of building a gainclone amplifier with many channels for a Home Theater Surround setup. The gainclone would drive the surround speakers, with a seperate sub (8" velodyne with 10" passive radiator), so not much bass is going to be going through the surround speakers at all. All I am really concerned about is the clarity and volume without distortion.

And which chip should I use? I have the following:

lm2876
LM1876
LM4780
LM1875
LM3886
LM3875
LM4766
OPA541
OPA549

Will the sound output from a well built surround amp using one of those chips be clearer and more detailed than the sound from a Denon 100Wx5 reciever (which I also have)?

Thanks for the help!

[soundNERD]

anybody?????

[Adam M.]

I just finished a 5 channel lm3886 gainclone based on national's schematic, slightly minimized, with the help of these fine people on the forum. It outperforms my Integra DTR 5.4 hands down. THe biggest difference I noticed between the 2 devices is the noise floor. The gainclone has NO hiss. Nada, Nothing when there is no input signal, the integra has a minor hiss, which during quiet passages of classical music can be annoying.

The associated equipment are Seas Thor based mains (no TL, Hiquphon OW1 replacing the millenium tweet), another DIY center, and MB20's as rears fed by a denon DVD-2200.

The gainclone amp will drive them all happily to a much louder volume than I would ever listen at, and it only gets warm, louder than the integra with all channels going, but not quite as loud using only 2-channel audio.

Very long story short, I like the lm3886, cause I have 4 ohm main speakers. :-)

[thomas997]

4780, 3886, 3875, and 549 would all be fine....


Depends on your speakers and really what you want.

3875 = simplicity
3886 = more power

etc.

[soundNERD]

I really want to go with a 549 because it has much more power than the 3886,

But would I lose sound quality with that over the 3886? Probably the 3875 would be the best, but if my speakers are ever 4ohm or below then it loses all power.

I have also noticed that the 549 has very little troubles driving a 2ohm speaker, which makes it even a better choice. I'm just worried about it being a Class B amp.

[Greg Erskine]

soundNERD,

Just build it and lets us know your results.

If you ask too many questions you'll get to many conflicting answers and you'll never start. Go with your gut feeling.

[Raccoon]

Adam.M :

I have similar project in my mind, but Im a total neewbie when it comes to amp design. I would be most interested on your design

-Raccoon-

[Adam M.]

THere wasn't anything special about my design, I took it directly from the national spec sheet and the minds of the folks on this forum.

I used 1K input resistor, 20k feedback resistor. 1kUF on the rails, and a large resistor for the mute resistor. Dind't use any of the optional parts or the mute cap. All that was done point to point.

I used a parts express 625VA transformer, and one bridge that was recommended by Siegfried Linkwitz on his website linkwitzlab.com. I had some 10,000uF caps laying around, so I used them on the bridge.

I used 5 Pentium 2 heatsinks, one for each channel and crammed them all into a 2u case. Make sure to read up on grounding, that caused me many problems!!!

The only change I would have made is in the layout. I put the transformer in the middle of the case trying to make it so one side wasn't tons heavier than the other...that made routing the wires harder...picked up tons of hum until I used careful wiring layout....Don't do that.

If you have more specific questions, please ask, but my knowledge may quickly run out and you'd need the more knowledgeable folks on this forum to help. :-)
-Adam