Sunn 200S

[Rknbkr12]

Hi, Folks!

Being of a non-technical nature, I have a question regarding the tube configurations of the Sunn 200S. My original which I purchased new in early 1967 had KT-88's. Is there a huge difference between these and the later 6550's that were used? Also, what difference is produced between a single rectifier tube and a dual rectifier tube setup?

Many thanks,
Iain McLennon

[loudthud]

The 6550 is an American equivalent of the KT88 although the KT88 has somewhat higher ratings. Sunn switched to 6550's around 1969 as either a cost cutting or availability move. Dual rectifiers??? The 2000S uses dual rectifiers because it takes two to provide enough current for 120W. The transformer in a 200S doesn't have the correct windings for two rectifiers.

[Rknbkr12]

Thank you for the information. When I had the amp gone through, I had specifically requested KT-88's to replace the 6550's. The repair (reads: Ripoff) facility ignored my request, stating it would have required rewiring for those tubes. It sounded odd to me then, but again, I'm not a techie.

As for the dual rectifier question, I've had the amp for sale recently, and one of the respondents asked if it had dual or single rectifiers. Without knowing what a rectifier is or what it does, all I could do was count the tubes on the left and respond appropriately.

Thank you again!

Iain

[loudthud]

No re-wiring required. The amp was designed to use KT88s. They probably didn't have any in stock. There is a guy in the Portland area that sells JJ tubes and has quite a Sunn collection. http://www.eurotubes.com/ He doesn't have a shop but maybe can reccommend someone.

[Rknbkr12]

Hi, Thud -

Yeah, I know Bob well - he re-tubed my Dual Showman head. I hate him because he won't part with any of his Sunns. I don't think there's a model he doesn't have at least one of! My dream (I have two, actually) is to come across a nice 1000S and/or a 1200S and have the available funds to take them off the market

So, what I hear you saying is that I could replace the 6550's with KT-88's with no reconfiguration. Would there be any advantage to doing so?

Cheers,
Iain

[loudthud]

No real advantage to KT88s. Your main concern is quality and reliability. Whoever put them in will probably guarantee them for at least 30 days. Make sure you play them hard at least once so if they are prone to failure, you weed out any weak ones.

[Rknbkr12]

Thanks, Thud - that boat has sailed and things are working fine. Have a very Happy New Year!

iain