Sunn Septre Dating

[JoeArthur]

Yah, thats what I meant Joe.  I guess I failed that chapter in phonics.....

Phonics was one of those things invented after I went to school, and a lot of people claim that "dirt" was also one of those things!!

Just one of those "old people" moments you have to look forward to...

    

[Isaac]

Damn, Joe. Yer, like, old and stuff.

[JoeArthur]

Hey!!! It still beats the alternative!!

[Isaac]

I couldn't agree more!

[Isaac]

My Septre amp tube chart says the power tubes are to be KT-88s. All the other Septres I've seen take 6550s. I also don't have that little slide-switch on the front panel. Anybody know if this is an earlier model of the Septre?

Have you taken the chassis out of the case, and looked for the date? There is almost always a date inside.

[EdBass]

I'm attempting to post this letter from Robert P Selby, Jr, announcing the switch to 6550's from KT88's. It's actually March 3rd, 1969, not September '69 as I thought. Let's hope this works...

[rick.heil]

Worked beautifully, thanks Ed!

[djc]

KT-88s can be substituted for 6550s. 6650s were original tubes, KT-88 are not.

Check the markings on all of the transformers/chokes. If they are original they can closely date the amp within something like +/- six months or so.

I have an original choke and output transformer.  How can I date my amp by these numbers?

[MrCreosote]

...I always liked the name "6550" better than "KT88"... (!)

[basiklybass]

My 200S has "10/17/67" in red grease pencil on the inside of the chassis with initials that I can't decipher. It looks like "JK" or maybe "LP".

Most everything I have read says that the KT88's sound better than the 6550's. The Dynaco was designed for KT88's.

I have KT88's in it. Maybe someday I'll try the 6550's.

[Soundmasterg]

I've tried both the 6550 and KT88 in my 200S's. My old '67 that I sold 10 years ago had Tung-Sol 6550's in it that were original and I replaced them with JJ KT88's. My '70 Sonic 1, which is a 200S essentially, had GE 6550A's in it when I got it, and I replaced them with JJ KT88's, but I also tried some NOS GE 6550A's and some SED/Winged C 6550C's. It sounded best with the JJ KT88's, and made more power too....70 watts RMS!