Author Topic: My model T does not match the schematics  (Read 119 times)

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Offline liwerks2

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My model T does not match the schematics
« on: June 18, 2022, 05:52:00 pm »
Good day, all:
    I have a Model T that I purchased from our guitarist back in the mid-1970's (one owner). I am under the impression that it is a early production model, and I am re-capping and re-tubing this beastie prior to possibly selling it (I am way too old for stage any more, and it's just tooo loud for use at home.
    My question revolves around that fact it does appear to be an early production model, but it has what appear to have line in, and a line out jacks on the back, and these do not appear in the schematics that I have. The inspection label appears to be dated as 9-23-71 or 9-23-74 (1974 seems more likely). To this point, I have not found a listing of serial numbers that would enable me to pinpoint the date any closer, although the SN plate #48847. I have included photos with this posting and would appreciate any illumination concerning exactly what do I currently have on my bench.
    I can provide more photos if someone would benefit from circuit details, etc.

    Thank you for your time and consideration. -L
Sunn Model T
Sunn 2000S
Kustom K100 combo
Ampeg SB-12
West Grande
2pc - 118RH cab
2000S cab
Sceptre (4x12) cab
Studio Bass (?) (2x15) cab
Fender Precision
Danelectro Longhorn
Gibson EB3
Ibanez bass (I don't know the model)

Offline Isaac

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Re: My model T does not match the schematics
« Reply #1 on: June 19, 2022, 11:16:11 am »
As far as I know, the Model T has always had a line out, and never had a line in. I don't see a line in in your photo, either. In most amps that have one, the line out comes after the preamp but before the power amp. In the case of the Model T, the line out comes after the power amp. It's just a couple of resistors to reduce the output voltage to a line level. You can make an external one for older amps that lack it.

I wonder if yours is an early production model. It doesn't have the finishing touches I would expect on an actual production unit. Labels written in Sharpie? Doesn't sound ready for prime time to me. Either the labels came off, or were never put on. Maybe a late prototype? Or maybe they just came off.
Isaac

Offline liwerks2

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Re: My model T does not match the schematics
« Reply #2 on: June 20, 2022, 10:29:55 am »
Alrightly! I did not understand how attachments work on this website, so here I try again to attach photos (my wife also thinks I can be trained, but the supporting evidence is minimal). Here is another photo of the back side of this amp with the in/out jacks in question. The amp (as I purchased it) had the typewritten labels on it that you can see in the photos. The writing in Sharpie was me ensuring that I could find the right jacks (for the speakers, etc.) in the near dark, which was consistent with the bars and cow barns that I played at in the 1970's.
The line out jack is certainly there, and that is consistent with the first gen schematics that I have, but there is also the input/output jacks near the speaker jacks.
I obtained this beastie used in the mid 1970's, so it could be an early prototype/production model, but I have no way of telling.

Now that I am in my late 60's, and between BMI/ASCAP and Covid19, there are no longer places for local bands to play, therefore I am prepping this amp for sale (along with 5 cabs and 5 other tube amps) and I want my description for Ebay to be accurate. (For some obscure reason my wife does not think big Sunn amps are suitable decorations for our living room. I disagree......if she is out of earshot.)

Later today I will modify my Model T 1st Gen schematics to include these jacks.
Sunn Model T
Sunn 2000S
Kustom K100 combo
Ampeg SB-12
West Grande
2pc - 118RH cab
2000S cab
Sceptre (4x12) cab
Studio Bass (?) (2x15) cab
Fender Precision
Danelectro Longhorn
Gibson EB3
Ibanez bass (I don't know the model)

Offline Isaac

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Re: My model T does not match the schematics
« Reply #3 on: June 21, 2022, 09:23:44 am »
Interesting. I've never seen anything like that on a Model T. I'd like to see how it's worked into the circuit.

Aside: a bandmate had a Fender tube amp with pre out and power in, but that was implemented via some solid state circuitry.

This is what I expect the rear panel on a Model T to look like, though mine is a 2G:
Isaac

Offline EdBass

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Re: My model T does not match the schematics
« Reply #4 on: June 21, 2022, 12:29:40 pm »
Some of the Sunn mega rigs of the late 60's/early 70's were similarly modified. I think someone posted pics of Pappalardi's Sunn rig with ins and outs here, but I can't find it.

A few years ago I had some conversation with Steven O'Malley from the band Sunn 0))). The emails are on a now defunct PC's hard drive, but I'm pretty sure he told me that he played 9 Model T's on stage simultaneously. I guess theoretically he could have daisy chained inputs, but I think it would be more likely that he had them rewired as the amp we're discussing here. Sunn

liwerks2; You got the rig from the original owner, right? Ask what and why they did the mods, that should settle it.