best 6550's for model t

[gray]

As stated by my other thread, I'm having my Model T worked on, and I'm thinking of retubing it. It takes 6550's, and I'm wondering what the best ones might be. Right now, I'm more concerned about what would be best, rather than what would be cost-efficient.
I thought of the JANs (if I could find a couple pairs) and Tung-Sols but frankly I don't know what would be the best. I play two Rickenbackers, a 4001 and a 4003, if that helps...

[Isaac]

Best would probably be some NOS Mullards or something like that.

[gray]

I see, thank you. Any idea what the best of today's production tubes might be for the Model T's?

[Isaac]

No, not from personal experience. A lot of people rave about the Eurotubes KT88's.

[gray]

Thanks, I just looked up their website, and I've found a couple different sites that talk about the JJ KT88's. I may have to try those if I can't find any NOS 6550's.  I haven't been using tube stuff long enough to know that KT88's and 6550's were interchangeable. I'll keep my eye out for Mullards, though.

[Isaac]

To be precise, they are not exact replacements for each other. They do have the same pinout, but the KT88 can take higher voltages. So, you can put a KT88 into a 6550 circuit, but not necessarily a 6550 into a KT88 circuit. The Sunns were originally designed for KT88s, but the 6550s seem to work fine in them. I know I've never had any trouble. However, I think I'm going to switch to KT88s when I next retube.

[AdmiralB]

Best would probably be some NOS Mullards or something like that.

Mullard never made 6550s or KT88s.  The only real KT88 was made by Genalex and only in England; the only real 6550s were made in the US and were made by Tung-Sol and Sylvania, and the 'A' revision by G.E.

6550s will work fine in any Sunn; there are some circuits where they cannot replace KT88s but Sunns don't qualify in that regard.

Nobody is making a real KT88 these days.  The tubes sold under that designation will work in Sunns, and will sound good (in the ear of the beholder) but they don't behave like real KT88s in the circuits that demand them (again, Sunn doesn't count here).

Current 6550s work well, but don't last nearly as long as G.E. 6550As, nor do they sound as rich as Tung-Sols.  But since a quad of either would exceed $300, I can live with that.  I prefer the tone of Svetlana (the original SED or 'Winged C') 6550s for guitar; I've heard the new Russian-made Tung-Sol is excellent but have not tried them.

[Sunn_Tubeamp_Revival]

Get hold of Bob at Eurotubes.com.  Do not pass on this!  The JJ KT88s are fantastic!!!  He will match a quad for you and take good care of getting them to you, making sure you are happy.  He is passionate about tubes and does not cut corners with service.

Regards,
Chuck

[gray]

I see! Thank you all for your input!  This gives me a lot more to work with, then, whether I go NOS or brand new.  I'm tempted to seek out the JJ KT88's if I can't find good NOS, unless anyone with more experience than I recommends otherwise.

[AdmiralB]

It's all a matter of taste, but I don't care for the JJ KT88s for guitar.  I use them in my 2000S - I like them for bass - but I prefer other tubes for six-string.

Bob is a good guy but that doesn't mean that JJs are the best thing for every type and application.

[gray]

Actually, I do play the bass. I'll be using the Model T with a Rickenbacker, potentially with a two-amp setup.

[thetiethatbinds]

i just re tubed my 1970 1200s with the new tung sol 6550's and there great...warm thick tone and mean breakup when cranked

[gray]

Hmm, interesting. Personally, I'm not sure how much breakup I really want, but it does depend on the quality. I can hear it sounding good with my Ricks. Thanks for the input.

[Soundmasterg]

I play guitar and bass, but only play bass (RIC 4001) through my Sunn 200S and 2000S. The 2000S is from '68 and has the used GE 6550A's that were in it when I got it, and the 200S is from '70 and is using JJ KT88's. I used to have a '67 all original 200S with 2x15 JBL equipped cabinet that had original Tung-Sol 6550's and later I put in JJ KT88's before I sold it. For bass, the JJ KT88's sound better to my ears than the GE 6550A's, although I do like the GE's a lot in my Ampeg SVT. The original Tung-Sol 6550 sounded VERY nice, but good luck finding any NOS for a reasonable price. The new Russian made Tung-Sol 6550's have been getting good reviews so far, but I haven't tried them yet so I can't comment on them. The Winged C/SED 6550C is a good tube and sounds nice, and I have some in my SVT currently, but I think the JJ sounds better than those for the Sunns. The JJ KT88 is a well made and long lasting tube, and sounds good. Bob at Eurotubes is a Sunn nut and has good service. You can also get the JJ's from other dealers like www.tubesandmore.com.

The KT88 is a better choice for the Sunns at their high voltages. The screen rating is exceeded in 6550's when used in a Sunn with today's wall voltages, whereas the KT88 has no problem with them. The 6550's will work, but the KT88's will work better IMO, and the 6550's may wear out sooner due to the circuit in the Sunns. If you're running a 6550 in a Sunn, I would suggest to add a series screen resistor if one is not in there already. Something like a 47ohm that is in the 2000S is probably fine. I believe the Model T already has the screen resistors, but if it doesn't adding one per tube socket will extend tube life.

Greg