Is my head a Sceptre, Sentura I or Other?

[theeevilelvis]

Hello All....maybe you can help me.  I recently acquired a Sunn head that has had all of its markings removed and I am having trouble identifying it.  After gathering all of the information I could, I believe that it is either a Sceptre or a Sentura I.  It has been modified in that it has had an extra gain stage inserted via two extra 12AX7's.  There is also a switch added to the front panel.  I can't decide whether I want to de-modify it or not, but I would definately like to identify it so that I may try to find a schematic or service manual to check what else may have been done to it.
I've uploaded a bunch of pics that you can check out on:  http://www.geocities.com/killbots2000/sunn.html
Any help or advice that you might be able to give me is greatly appreciated.  Thanks!!

Thee Evil Elvis

[Spectrum II]

I have no idea what I'm talking about technically, but...

From what I could gather from the catalog info provided on this site is that the Sceptre is going to be putting out more power (60 watts RMS, 140 peak) than the Sentura I (40 watts RMS, 90 watts peak). I can see that behind your power cord what looks like it says "140 watts" on the last line of the label, which would rule out the Sentura I.

It has to either be a Sceptre or Sentura II. I'm gonna go with Sceptre.

I have the same going on with my Spectrum II head. From what I can gather it's built like a 2000s & that it had been mentioned that Jimi Hendrix had used a Spectrum II model that was set up the same way, but wasn't pleased with the way it sounded (the 4 KT88's didn't break up as fast as the EL34 loaded Marshalls that he was used to). As a bass amp, I couldn't be more pleased.

[Spectrum II]

Sceptre also have that black toggle switch between the tremolo & reverb controls. The Senturas do not.

[pennierich]

From what I can tell, it appears that you have a 1200S top from the late 60's.

The Sentura ll and Sceptre were not 24 inches long but the 1200S and 2000S were.

If you send me an address, I will mail a copy of the schematic and any other service info I have. I will be back to my office next Monday and will try to get them out. After that, I will be on the road for a couple of weeks.

pennierich

richard@pennierich.com

[Anonymous]

I must disagree with pennierich regarding the length of the 2000S and 1200S amp head cabinets. They were 30" long. All of the 40 watt (2-EL34's) and 60 watt (2-6550 or 2-KT88) heads (after 1967) were 24" long. I just measured my 1969 2000S and my 1971 200S and that is what they measure. The only exception is the original Coliseum PA head (4-6550 tubes) that had a 24" cabinet (I owned one of these too).
Ryan

[pennierich]

I stand corrected. I guess I must have been half awake when I wrote my response.

I build cabinets based on the old Sunn schematics and plans and I should have known the measurements because I use them all the time.

Thanks for correcting me.      

[Isaac]

I have never seen a Sceptre with EL34s, so I have to go with the Sentura I. Also, Spectrum II says that the Senturas don't have a switch between the reverb and tremolo controls, but my Sentura II does. For nitpickers, it's a slide switch, not a toggle switch.

Spectrum II, where do you see 140 Watts? No matter, the power ratings on the labels near the power cords are for power consumption, not power output.