Vintage 6550 Quad

[Walt-Dogg]

As good as my Model T sounds great solely as a bass amp, I would very much like to be able to use it as a more toneful guitar amp and toneful amp in general with swapping the 6550s with KT-88s. So, here's the kicker, there's no point in changing my tubes right now, as the 6550s in my Model T are original to the amp from 1974 and still have plenty of life in them. Also my MIG 100 H has taken over as my guitar amp since the Model T is dual functional and sounds better as a bass amp anyways because of the 6550s. In short, I want to sell or trade my matched 1974 quad of Sylvania 6550s or trade them for a matched set of KT-88s with plenty of life in them.

[Walt-Dogg]

Or even a different set of 6550s. I just don't like how it sounds driven for guitar.

[MammothVolume]

Whatchou got in mind for a price? I wouldn't mind backups for my T...

[EdBass]

Interesting tube opinion. I think most people consider the 6550 and KT88 pretty much interchangeable, but generally consider the KT88 a more "bass friendly" tube than the 6550.
6550's usually break up a little smoother and quicker and KT88's are more prone to stay cleaner longer and then break all at once. They also generally break up a little harsher than 6550's, not as smooth and musical, hence the general consensus they are a better "bass" tube than the 6550; which ultimately has less clean power but is more "toneful" than the KT88.

The differences are very subtle though, and what one person likes may be the opposite of someone else. The history of Sylvania 6550A's in the 70's is a little convoluted and debatable; not as popular or desireable as vintage GE's or Tung Sols but if your amp has the original tubes they might be rebranded GE built under contract for Sylvania, and if they are and still test well they will likely perform much better (and be worth more $$) overall in that circuit than any new replacement you can get regardless of whether you are using the amp for bass or guitar.
Have you tested the tubes? If so, what are the readings?

[Walt-Dogg]

$170-$190, maybe I think would be fair.

You know Ed, you maybe be very much right about the tubes sounding best in only my amp. And for as much I appreciate tubes and tube amps, maybe I just don't like how they sound. But solid state amps can only be so nice compared to a tube amp and REALLY good solid state amps are far and few between.

[tacklebox455]

hey walt if your wanting the tubes to break up quicker try a quad of soft tung-sol's great with guitar

[Walt-Dogg]

Actually, based upon how my Sovtek sounds with it's quad of EH 6L6s and trio of Sovtek 12AX7s. I kind of want to try the same set up in my Model T but with 6550s instead of 6L6s of course. I do at some point want to try Tung-Sols, in fact a few months back when I was got the T those were what I was looking to get as the previous owner told me he was going to have to retube it soon and not be able to afford it or sell the amp.
And for price I'm going to settle on $250 shipped which I think after having done some research on NOS 1970s Sylvania 6550s is pretty good.

[tacklebox455]

are the yellow lettered sylvania's? if they are and slinder bottle type there rebranded GE's (great tubes btw)
if you wanted to run eh or whatever brand doesnt matter long as you get soft breakup so they break up quicker.

i have used the tung-sol 6550's,6l6's,and 5881's are 3 really impressed me the reissue tung-sol 6550's sound and tone are really close to the NOS tung-sol's and for the money its a steal. let us know what ya get and how it sounds im a tube whore so i'm always interested in something that someone trys that i have'nt

[Walt-Dogg]

Yes to all of that. I'm very much aware/certain if the tubes' origins.

I don't necessarily need earlier breakup, the tone just seems sterile, I think changing the preamp tubes first would be the best idea for that since the Model T is 150 watts anyways and I want to try Sovteks because I was planning on using them anyways.

I'll give this thread some closure when I something happens to the 6550s.

[tacklebox455]

only reason i mentioned soft break up thought you might be trying to get distorted at lower volumes.

very nice on the original tubes