Resurrection: Old Parts - New Amp.

[MJL21193]

Originally posted by jaycee
but am cautious about using them because they are pretty much irreplaceable.

Tennyson said it best: "Better to have loved and lost than never to have loved at all"
I say use 'em, and if they break, are you any worse off? They are only valuable if you put them to good use.

As for the ceramics, the 100pF I have are 500V AVX and I couldn't see a difference during testing. Some (many) have prejudices against certain type of caps and ceramic is no exception. I would like to know if there is a truly valid reason for this bias. I have yet to open an older receiver or amp that has a silver mica anywhere to be seen. Granted, none of the amps I scrap are "audiophile" quality.

[ostripper]

By mjl - I have yet to open an older receiver or amp that has a silver mica anywhere to be seen. Granted, none of the amps I scrap are "audiophile" quality.

yes , junk (except for trafo and some good 8200uf 63v caps)
on sony/fisher ,etc.. they use multilayer ceramics for signal
path (miller ,filters) and only use el cheepo round disk
ceramics for bypass and stray capacitance duty..
OS

[SQLGuy]

Originally posted by jaycee
I have some nice 2SK389 dual FET's from the Teac amp I gutted, but am cautious about using them because they are pretty much irreplaceable.

Not exactly irreplacable...

Linear Systems has what they claim is an improved replacement for the 2SK389's - their number LSK389. You can buy them in small quantities from Trendsetter with a $25 minimum order.

[jaycee]

That's what i mean by "pretty much" irreplaceable - the only replacements are either NOS, or hard to get expensive parts.

[SQLGuy]

It's a $25 minimum order, not $25 a piece, not even $25 per part number. Not sure how much the LSK389's are, but the metal can LS844's I bought the other day were $6.50 a piece.

[jaycee]

That's nearly £17 in my currency, and undoubtedly i'd have to pay extra on top of that for shipping and tax. And what would I do with the surplus parts?

I'll keep them for something like a headphone amp. If they go in that, i'd be more prepared to build a new circuit than i would be prepared to rebuild a 100W/8 ohms power amp.

[MJL21193]

Originally posted by ostripper


yes , junk (except for trafo and some good 8200uf 63v caps)
on sony/fisher ,etc..

The transformers and heatsinks, case if you can recycle it. Transistors, film caps (tons), rectifier diodes, screws, fuse holders, pots, knobs and hardware, etc. I draw the line at resistors (too much work to measure and sort each) and electrolytic, especially the PS ones. Life span and unknown abuse are factors. I had an Akia that had one that was swollen and the other had ruptured. Some things are not worth saving.

Originally posted by jaycee
. And what would I do with the surplus parts?

Sell them to someone here. I wouldn't want them though...my ears are not golden enough for such refinements. Low noise bjt inputs are as good as it needs to be for me.

New schematic. I have added decoupling to the cascode to ground and tidied it up a bit.
The Vbe multiplier will use the 2SC4137 which I found in a Kenwood receiver. These are supposed to be for temperature compensation and have incredibly high gain. I'm not sure if I have the Vbe multiplier configured properly for there use. I guess I will need to try it and see.

[jkeny]

I use to regularly visit my local recycling centre although I haven't been in a year or more. Great source for parts although they don't like you taking things away - in fact openly object to it. Seeing as you have to pay €15 to drop anything off I reckon you should also be allowed to pick up anything you might find useful - I see the staff do it themselves.

Anyway, some goodies I retrieved include
- a Rogers Cadet III tube amplifier- fully working with 4 ECL86 tubes & 3 ECC807 tubes (worth about €100 on ebay) - I've since rebuilt it into a Baby Huey amp using the PS & o/p trafos & tubes
- 3 Samson servo 550 studio amplifiers 275W per channel - all working except for one - good source for large heatsinks, case, 55-0-55 trafo ( I've used one of these as a voltage converter for US gear - gives balanced power), 6 SA1943 & 6 SC5200 + driver transistors in each amp - I'm building a Krill O/p stage with these
- Rega planar II turntable with glass platter - needs a belt.

All of these were found in good shape mainly because I was lucky & lots of other junk hadn't been thrown in on top of them. It breaks my heart to think of all the good stuff that has gone to be broken down in the year I've been away.

When I retire I want a job there!

[MJL21193]

Originally posted by jkeny

When I retire I want a job there!

Excellent finds! I leave the tube stuff where I find it though.

I hit the garage sales (occasionally) in the summer and Goodwill, Sally Ann. "Antique" shops/used furniture though these are expensive - no fun unless it cost nothing or next to it.
The garage sales are really good for vinyl - I found a giant stack last year, asked the lady how much for the lot. $5.00 for almost 100 records in near perfect shape.

I have the schematic where I want it (assume it's ok, no comments from the audience) and I've started the layout. The heatsink (pictured above) has a angle on the bottom, a place for the outputs to mount vertically with the sink standing up and a place on the bottom of the angle to fasten the sink (and PCB) to the chassis. Both channels are on this heatsink so I need to make a fairly narrow layout.
BTW, amps will be ~60 watts per channel, over voltage is for clipping headroom.

[jacco vermeulen]

Originally posted by MJL21193
and marshal NEC.

Slurp, the Black & Blue velvet pimp devices are lovely.
(Harman Kardon assassin ?)