My Amp is Broken - Not Sure What to Do - Any Recommendations?

Parts go obsolete, I've had to run down a lot of obsolete parts, some companies have made products using discontinued parts, knowing before their production run that the parts had been discontinued!

If you really liked that amp, I'd contact Roy Mottram at tubes4hifi.com, he has designed many tube amps, preamps, and phono preamps. You could also contact Don Sachs, but it's unlikely that he'll do repairs, last I knew he was way behind in making his own amps and preamps. Anyway, those guys are big on tube circuit design and may have already worked on your problem for someone else.

Oh, there is one other option I could suggest. Vandersteens are not the most articulate speakers out there, so you can probably procrastinate doing a bridge rectifier mod to it, but there is a PS Audio 200C amplifier on eBay right now. I think he has come down at least 100, and it may be 100 and free shipping, I don't recall if he was throwing in shipping or not initially. $700 is still a little high for that amp, but it will drive the Vandys with no problems. I have a friend who is borrowing one of my 2 PS amps for his Vandy 2CE Signatures and he loves it. Obviously owning 2 of them, you know that for a transistor amplifier I really like them for the money. BTW, I would try offering him $550, and even that may be high for a stock amp, but no way would I pay more than 600 shipped, and make sure it's insured, clumsy delivery people can destroy an amp with the monster coil it has if they drop it the wrong way.

I think the slew rate is a crazy 400V per millisecond, my tube amp is 60? It owns speakers, back in the day it was one of only a few that could really drive the big Appoge speakers, which went down to 2 ohms. You will fry the amp if you plug or unplug your preamp or speakers while it's turned on though,  and the relay buzzes. A lot of folks think it's the coil, but the relay chatters, if you go that way, there is a company that makes a direct replacement for about 60 dollars. It's one of those, if it bothers you things. It's worth it because you would have to spend a ton to get another transistor amp that sounds as good, much less that can drive a load like the 200C or 200CX.

The other thing is, like most amps of its age, the bridge rectifiers suck! So at some point you really should replace them with Fred's, Hexfreds, or Stealth diodes, I prefer to use IXYS Freds from Partsconnexion, or Michael Percy Audio.  Anyone who can solder should be able to easily replace them for you. It wouldn't hurt to add some nice bypass caps to the power supply. One of mine has a TX2575 resistor on the input, and I am probably going to go through and replace all the resistors in it. I am a detail freak, it is just a shade dark, but like the old Forte F44 preamp, it's actually a pretty awesome viscerally pleasing sound, which is why I have never gone that far with one. I have replaced the caps on the boards with Black Gates, but the bridge rectifiers are what it really needs to fully come into its own. I have been told that some Levenson amps can really control speakers, I can't speak to that, but the PS amp owns what ever I have thrown at them.
 

Look, I have B&W 801M’s with all caps in series with the speakers bypassed with Audyn True Copper Max caps. Thiel CS-7 speakers, Paradigm Studio Reference 100 V2’s Ellis Audio 1801’s, KEF Reference 105s I have had Quad ELS57s, Acoustat 3300’s Acoustat Mdl 3s, Vandersteen 1Bs, 2CE Signatures, etc. All the Vandersteen speakers that I have heard, including 3A Signatures as I recall, sound like pretty good speakers with blankets over the tweeters. As a test, I bypassed the T-H-R-E-E capacitors IN SERIES on the 2CE Signatures tweeters with a .1uf V-Cap, it made ears bleed. They knocked down they highs so the tweeters were not crazy hot. As a test, I installed a pair of Hiquphon tweeters, they didn’t have the range of the Vandersteen tweeters, and the crossover was tuned to the Vandersteen tweeters, but the details were now there without the harsh highs as they should have been all along. A friend was over and immediately fell in love with them. I explained that with those tweeters there would be issues, but he loves them anyway, and he wanted nothing to do with them without and especially with the V-Caps until I decided to try out the Hiquphons. So, I know bright from dark, and frankly I now have a full range driver and with no crossover whatever, that is THE most detailed speaker I have EVER heard. In fact I pretty much had to revamp my entire stereo because of the ability of these drivers to revel details. Anyway, Vandersteens excel at masking upstream issues. They sound very musical, very enjoyable unless you are about really drilling down on detail. Detail can ruin an otherwise beautiful song. Poor recordings, less than awesome equipment, etc., etc., are all good reasons to love Vandersteen speakers. Relentless details are not for everyone! If you love Vandersteens, that’s great, enjoy them. Everyone has different goals where their listening is concerned. Find yours, and enjoy before you end up with a ridiculous list of gear that you have bought and sold!

Ouch! The government regulates support for equipment, but sometimes even that ends up being ignored. A manufacturer is supposed to stock enough spares to last X years depending upon the product. Stereos are likely about 3 years. Near the end of tube screen TVs a salesman told me that one TV had a faulty horizontal flyback transformer issue, and they had run out of spares, but were still selling the TVs, so the spares are judged based upon estimates/projections not actual parts lives.

johnsonwu, cool!

"Do you guys think it would alter the sound to replace the 3281D and 1302D Thermal Trak transistors with NJL3281DG (NPN) NJL1302DG (PNP) Thermal Trak transistors, and do you think the work to match the output devices would be difficult or highly involved?"

Matching devices properly is expensive and a pain. You have to buy a ton of them to get the matched sets you need. Jon Soderberg repairs old Threshold amps, he buys transistors in lots, then sorts them according to which matches which. If you do that you’ll end up with a very large number of devices that you’ll have no use for. Unless you are going to do a lot of amps, once you get a matched set, all the rest are pretty much useless to you. Someone who does it all the time will just keep putting together matched sets. The few oddballs left will be matched up when he buys another lot.

If you have no need to replace the output devices, leave them alone. I have been fortunate enough to have always found someone who matches them, so I don’t have to. They cost a lot more, but far less than it would cost to buy enough to get a matched set!

It depends upon how tight you want them matched I suppose, and if you want to set up a test bed for them, etc. I just have better things to do. I have a pile of gear to troubleshoot and repair as it is...