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Vintage Asylum Classic gear from yesteryear; vintage audio standing the test of time. |
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Vintage Asylum Classic gear from yesteryear; vintage audio standing the test of time. |
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In Reply to: Fisher 500-B advice needed posted by Jack Ostroff on November 24, 2001 at 09:20:46:
I'm not sure what degree of restoration would be required for your unit. I think it depends on what the cause of its "degrading" is. If it's just the usual suspects with these units (tired rectifer, beat up main coupling caps, leaky small lytics, a spent 6AQ8), you can buy one of the packaged "resto" kits and have someone do it. However, if you're having a tech do it anyway, anyone who knows what they're doing can order the parts from a jobber like Mouser and save you a bunch over the prepackaged kits, which are more directed to the hobbyist with limited experience. And you're gonna hear 900 different opinions on coupling caps and resistors, both on this board and among the "experts". Personally I've tried a lot of them, including the IC and Sprague polyesters, and I like Sprague 716p (at under $2 each) the best for these units. Whatever you do, don't let someone stuff it full of Solens, Hovlands or other designer caps. Totally unnecessary here. I'd try to stick with carbon comps in the signal path. But most of the OEM resistors are extremely sturdy and dead on accurate even after 40 years, many being precision W. German carbon films. In fact, Fisher used a large number of German-made parts in these units. Unfortunately, the small German electrolytics don't hold up so well. Unless it's humming or they're really hot, the filter caps are OK, and don't let someone talk you into replacing them. Fisher's filter caps generally only fail from non-use, and that is clearly not the case here.As far as techs go, the 500B isn't a nuclear device, and there are a lot of older local techs who are likely perfectly competent with them. Just don't let them do a wholesale parts exchange to make it "modern" or you may find yourself very unhappy with the sound and an excessive parts bill. I know Paul at Bizzy Bee well - he does good work. The FisherDoc is THE EXPERT on these Fishers with access to virtually every conceivable part it could need and is an artist. But he can be extremely slow - painfully so - is not inexpensive and some of his FM mods are controversal to some. Another choice for Fisher service on the west coast is Mike Zuccaro, who does my alignments. But again, any local tech with more than 20 yrs experience has likely seen one of these and they're not that complex. The hard part, the part requiring real experience, will be the FM alignment. Unless the guy's done Fishers before, don't let him touch the alignment, or he'll likely screw it up. Try to do the minimum service necessary to set things straight - the more you change, the more it will change. Have the tubes checked, replace the 6AQ8 tube, replace the main coupling caps, get some cathode fuses on those 7591 puppies and redo the bias voltage circuit up to about -22v and that should resolve or at least pinpoint most of your issues.
Now if your problems are caused by tiring 7591s and/or 12AX7s, then you could run up a good sized bill, especially if you go the NOS retube route. I would think if you've been running this 500B bare stock for years, there's a chance those 7591s could be used up, especially at the bias voltages Fisher originally specified. Lucky for you that EH now makes decent new production direct-fit 7591As for about $80 per quad. I'd be really surprised if the X7s are shot, but I guess it happens. I love old Mullards and Amperexes here (and what Fisher typically used), but if you want to do it on the cheap, try noise-tested shiny plate EIs, which are surprisingly sweet and the closest sound to the original Fishers among new production, for about $12 each. Don't mess with the 6AU6s unless they're truly used up, or you will need an alignment.
I certainly think a functional 500B is worth restoring in any event. I own one, along with a bunch of other vintage Fisher stuff, and it's all good gear. What I suggested above should significantly improve the sound without losing the magic designed into these units. But if you're going to move on, I guess you could get $250-300 for it on ebay in running condition, and a bit more if it has a cabinet. And when you fire up that new Rotel, you'll wonder why you ever got rid of it.
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Follow Ups
- Re: Fisher 500-B advice needed - sgmlaw 11/24/0121:35:53 11/24/01 (0)
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