Vintage Fisher TX-300 Integrated needs caps

A few things:

a) After a certain basic level of quality construction, a cap is a cap is a cap. So, within the universe of film caps, after that level, there is effe ctively nothing to choose between brands. Similarly within the universe of electrolytic caps.

b) at less than 5uF, moving from electrolytic caps to film caps is generall y a good thing. Keep in mind that a typical electrolytic cap has a toleranc e of -20% to +100% unless screened. The typical film cap (these days) is us ually within 5% or less. So, a film cap will be far closer ab initio, and a lso stay that way. Above 5%, you may run into real-estate problems, so mak e sure the film cap will fit before making a purchase.

c) Voicing Reasons: Not really. Supply availability is far more likely and/ or actual tolerance.

d) Better to 4.7 than 3.3. The 3.3 is at the bottom end of the electrolytic tolerance scale, 4.7 is close enough on the upper end.

e) Make your voltage *AT LEAST* 20% higher than OEM. Try to be "not more" t han 100% if possible. Much more an issue with electrolytic than with film c aps. I stock film caps in 200 (anything less than 100V) and 600/650V (anyth ing above to 550V).

Enjoy! That is a fine unit! Fisher iron is legendary.

Digikey is a fine source, also Mouser and Newark. All three will sell you q uality goods.

Peter Wieck Melrose Park, PA

** Just use any brand name 4.7uF, 63V electros.

Panasonic, Nippon-Chemicon etc.

IMO, 1960s Germanium transistor amplifiers are the "missing link" between tube and modern solid state - and they should stay missing.

.... Phil

.... Phil

OK - a valid opinion. On the other hand, this particular unit does use transistors that are still readily available, so a worthwhile bit of history for all that.

Peter Wieck Melrose Park, PA

** You must have a different idea of "readily available" to mine.

The original RCA 35144s PNP outputs are not easy to find ( no listings on Ebay) and the only similar type I can find from a dealer is the AD149.

... Phil

Didn't suggest they were cheap, just readily available.

The NTE (by direct experience) is a drop-in replacement for the OEM in actual function. Or so it worked for me on a vintage KLH product back in the day. That amp is still working, as it happens.

I also agree that in the US, we have access to a much greater array of relatively local (2 days by cheap mail) suppliers than many other parts of the world.

Would I spend US$100 restoring this amp? Not for me, but given the cult status of vintage Fisher in the US, perhaps for that market.

Peter Wieck Melrose Park, PA

** Then you are wrong on both counts.

** The NTE179 is nothing like the original RCA part and is very expensive.

OTOH, the AD149 is very close as sells for under US$10 on Ebay or just over A$5 from the store I usually frequent here in Sydney.

.... Phil

n tube and modern solid state - and they should stay missing.

Heheh... funny.

Phil: is your objection to 60s germanium amplifiers their performance, quir kiness, or parts availability (or all three).

Peter: none of the outputs are blown, so I don't need to acquire any ge for now, although I wouldn't mind picking up a set just to have. It is a very handsome and flexible amplifier if nothing else.

After doing some resistance checks around the output transistor, it's surpr ising that the outputs didn't blow. The bias controls read between 15 and 2

0 ohms before I marked their exact position and cleaned them. Once cleaned , lubed, and put back on the spot, they averaged about 6 ohms (and they're shunted by 22 ohm resistors). In the manual I have, there is a note about replacing the 22 ohm resistors with 10 ohm ones. Apparently, the bias pots may have been problematic from early on. The note also said to replace all four pots if suspect. Since the manual is of the same year as the amp, it tells me something about them. Perhaps those inert coupling caps prevented the output stage from blowing.