| HDTVman |
I just finished my second 2 channel amp. using the National 3875 chip amp. The first one had some problems and was a retro fit for an old SS amp that was laying around. It just didn't work very well. I think the amp had some power supply problems.
The new one is a whole different story. I like this one a lot. It's scratch built, air terminial construction. It has a single +-22VDC pie type power supply. Transformer is 34VAC CT @ about 400VA, one bridge rect. from the junk box, 2 4700uf no name caps, a .47 ohm 5 watt resistor in series for each rail and then 2 9600uf no name caps. Just 10uf at the chip X 2, one for each rail.
I banged together a case from 3/4 inch plywood and masionite(sp) and some old heet sinks I had laying around. I think I have about $15 bucks in it.
It sounds very good. I am driving a pair of 4.5 inch RS speakers in TL enclosures and the computer is the source.
Oh ya, this is a non inverting amp.
Later BZ:geezer:
Just wanted to add that I used the part values from the National data sheet |
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| planet10 |
| quote: | Originally posted by HDTVman
I am driving a pair of 4.5 inch RS speakers in TL enclosures |
Which ones? Got some pictures?
dave |
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| HDTVman |
Hi Dave
I made a mistake about the driver size. The ones I used were 4" RS 40-1040 with a spec. response of 80-20kHz. The TL was inspired by something I saw on your site, Rob Sampson's "Boomtubes". I am please with the sound of these but they do need some EQ to sound there best.
Later BZ:geezer: |
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| planet10 |
| quote: | Originally posted by HDTVman
4" RS 40-1040 .... Rob Sampson's "Boomtubes" |
:)
Pictures?
dave |
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| HDTVman |
| Ok Dave, I don't have much luck at this but here goes. |
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| HDTVman |
And here is the amp.
Later BZ:geezer: |
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