Posted: Sun Oct 28, 2007 1:23 am
erichayes wrote:The guy who has the amp is out on tour and his wife can't find it, so I'll just have to wait until he checks in. Almost all of those amps were built by Original Equipment Manufacturers (OEMs) like Matsushita, Hitachi, Toshiba, Trio etc for second-steppers like Lafayette, Western Auto, Radio Shack etc, who would put their brand names on them and sell them "exclusively". Usually, the only differences between amps of the same OEM were the speaker size and whether or not it had tremolo.
When I spoke of leaky coupling caps, I was referring to electrical leakage, although those particular caps did leak physically as well. If, indeed, the amp led a benign life, there might not be that much heat damage and the caps could be good to go for a while. The resistors, on the other hand, are losers out of the chute. I had some NOS I picked up at a hamfest that were all over the map--high, low, and one or two that were dead on.
For replacement caps, I'd use either SBE Orange Drops or Illinois metallized polyprops. Xicons are OK if you're on a budget, but I don't know what long term heat effects there might be.
For resistors, I use Xicon small size metal oxide or NTE 2% flameproof (also metal oxide). MO can handle the heat much better than carbon film or composition resistors do, and they don't drift with age. A small size 1 W MO is virtually the same physical size as a ½ W composition, so there isn't a space issue.
The rubber band effect is the result of an incompetent, lazy or inexperienced tech doing a half-assed repair on a piece of equipment, causing it to snap back into the shop until the job is finally done properly.
Eric,
Thanks for the cool info. Perhaps then Matsushita built this Kawai as it's the brand on the speaker.
How much will the sound change if caps and resistors are changed? Is there such a thing as dialing in resistors and caps on an amp, even if the values are the same as the original? Handpicking the parts, as it were, trying them in the circuit to see the effect? Is there a way to tell sound wise if parts need changing?
Goff