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The Gold Lion KT-66's arrived today. Pace Tom, but these are muuuuuch better, sound like real KT-66's to me. The Chinese ones didn't sound at all nice in this amp.

I don't know. Some used pentode outputs and other used triodes, but I don't know about the circuits. A lot of HF-60s were destroyed for these OTs.

LOL. Was that Vu ripping them apart? I seem to recall he had a fondness for Acros...

I want to add that after a few hours these Gold Lion KT66's are **lovely** in these amps. The 807s are good but these are really beautiful. I think this is a keeper. At $130 a quad from Viva Tubes, I can afford to splurge a bit.

And by the way, if you don't know Viva Tubes, they're a really fine eBay seller that's opened a web shop featuring new, NOS and used tubes, as well as vintage trannies and other components. I have always found them ultra-reliable with good prices and prompt shipping.

During the late 1980's, early 90's, I was involved with inspecting Ticonderoga Class (CG-47) cruisers under construction at Ingalls Shipbuilding in Pascagoula, MS. Anyway, when I was down in one of the Sonar Room on one inspection, I noticed a McIntosh tube amplifier that was being used for sonar system testing. Don't remember the model number, however.

The installed sonar cabinets still used Nixie tube displays, BTW.

David

Cool! Thanks for confirming that!

Thought I'd update everyone on this. Learned a lot about Williamson amplifiers in the past 6 months. The key thing I've learned is that you can't improvise! At some point I'd like to do one of the following: Order a pair of Sowter "Williamson" OPTs, or Heyboer's Peerless S-265-Q clones, or find a mate for my Patridge, and build a vintage Williamson. It would probably be stable enough and it would be a good project for learning how to properly test an amp for stability and bandwidth. In the meantime, I've built this:

http://audiokarma.org/forums/index.php? ... ld.795322/

I found a very clean, working pair of Heathkit W4's on eBay for $400 (!) and have modified them accordingly. It's a lovely amp, sounds much more powerful than it should thanks to the low distortion. Definitely not missing those 300Bs now. Highly recommended if you can find a a pair of the Stancor 51-17 outputs. There are still some "for parts" W4's on ebay and chances are the OPTs are good.

But I have my eye on what I think will be even better. Found a pair of Peerless 16277's on eBay just the other day, so I'll be doing this:

http://audiokarma.org/forums/index.php? ... 2m.767851/

I like the KT66 and the Peerless should be very sweet. And I can go either triode or "ultralinear" with just a few quick mods. I think this will probably satisfy my goal of getting as close to an original Williamson as possible while knowing that stability and distortion are well under control.

That would take care of any issues getting a good soundstage. Since soundstage is a big part of what I'm after, mono is not for me.

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Dave,

My memory may not be accurate, aren't your ribbon tweeters beside the main speaker box like this?



If so, your ribbons might be suffering from the mid range edge diffraction of the box. I would handle it first. Try positioning the tweeter on top of the box, slightly forward of the front face of the box and tilted down aiming at the listening position.

Yup, there has been some discussion about a mono setup. It would certainly standout.....



This is probably not a popular opinion here (since LOTS of people here use resistive passives or pots on their amps) but I have virtually never heard a system that did not sound better with an active preamp compared to resistor based passives. I have heard plenty of GREAT sounding system that use passives/pots but I suspect I would like them more with a good preamp in the chain. In cases where I have actually compared the use of an active preamp vs a simple attenuator in a system, with the passive device is almost always sounds cleaner, less distorted, more transparent and also strangle Hifi and artificial in a way that is hard to describe and ultimately a turnoff. And this in cases where impedance issues should really not have a significant impact (short connections, high input impedance amps with fairly stout sources etc etc). Autoformers (which I use) seem to split the difference between active preamps and attenuators but I still have the sneaking suspicion that I would be better off building a really good active preamp.

I've got an NOS pair of UTC LS-61s I've been saving for a project like this. One of these days....

Roscoe

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