Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: kagliostro on June 14, 2016, 04:24:46 pm

Title: In wich amp was used the Duette Ampeg Preamp ? (that uses a 6SJ7 as optional)
Post by: kagliostro on June 14, 2016, 04:24:46 pm

I've find this interesting preamp schematic (to me is interesting that there is a tone control that follows a pentode)

(http://i.imgur.com/nb1ShUd.jpg)

I would like to know more about this 6SJ7 optional pentode channel used on the Duette, someone has news about ?

Which is the schematic of the whole amp ?

Thanks

Franco

Title: Re: In wich amp was used the Duette Ampeg Preamp ? (that uses a 6SJ7 as optional)
Post by: sluckey on June 15, 2016, 07:03:43 am

You have found a rare bird! Those amps were only around for a short time. They were built in a combo cabinet with a split chassis design. Preamp(s) up top, power amp/power supply down in the bottom of the cab. The power amps were a simple push/pull design. At least a couple different power amps were used. I see some reference to the power amps being called a '600' or '700' series amp, but I cannot find any schematic. The amps were said to have a clean sound well suited for jazz players. I found a few pics but no technical info other than the schematic you posted.

Title: Re: In wich amp was used the Duette Ampeg Preamp ? (that uses a 6SJ7 as optional)
Post by: kagliostro on June 15, 2016, 07:35:01 am

Ciao Steve

Yes, people refers to this amp as a good amp for Jazz

a bit of more info can be read here, unfortunately no schematic

http://www.ggjaguar.com/duette.htm (http://www.ggjaguar.com/duette.htm)

I think it was an interesting amp

Franco


p.s.: This 835 runs a pair of EL37 as the Duette


(http://i.imgur.com/mLXMXLq.jpg)

Title: Re: In wich amp was used the Duette Ampeg Preamp ? (that uses a 6SJ7 as optional)
Post by: sluckey on June 15, 2016, 07:39:59 am

I saw that page. There are also a couple pics elsewhere showing the back of the cab with split chassis.

Title: Re: In wich amp was used the Duette Ampeg Preamp ? (that uses a 6SJ7 as optional)
Post by: kagliostro on June 15, 2016, 08:00:02 am

Yes ... isn't cool ?  :grin:


Franco

Title: Re: In wich amp was used the Duette Ampeg Preamp ? (that uses a 6SJ7 as optional)
Post by: sluckey on June 15, 2016, 08:04:47 am

Here's some more info on those amps. Nothing very technical but still interesting...

https://books.google.com/books?id=O36Ro9MSkccC&pg=RA1-PA61&lpg=RA1-PA61&dq=ampeg+700+series+amp&source=bl&ots=X4-C7M2Yfo&sig=50B8ZJBIE9eta_tySJpKBRsV3iQ&hl=en&sa=X&ved=0ahUKEwjDi5KmiKrNAhXKQSYKHeC_CP4Q6AEIZTAE#v=onepage&q=ampeg%20700%20series%20amp&f=false
 (https://books.google.com/books?id=O36Ro9MSkccC&pg=RA1-PA61&lpg=RA1-PA61&dq=ampeg+700+series+amp&source=bl&ots=X4-C7M2Yfo&sig=50B8ZJBIE9eta_tySJpKBRsV3iQ&hl=en&sa=X&ved=0ahUKEwjDi5KmiKrNAhXKQSYKHeC_CP4Q6AEIZTAE#v=onepage&q=ampeg%20700%20series%20amp&f=false)

Title: Re: In wich amp was used the Duette Ampeg Preamp ? (that uses a 6SJ7 as optional)
Post by: shooter on June 15, 2016, 08:30:01 am

Franco, you do find some interesting things!  surfing, I stumbled across an early reverberocket that uses a 6BK11 triple triode tube!! then I went looking for tube data, then......, then.....,then  I went to bed!

Title: Re: In wich amp was used the Duette Ampeg Preamp ? (that uses a 6SJ7 as optional)
Post by: kagliostro on June 15, 2016, 08:40:49 am

Thanks Steve

Hey Shooter something like the 6C10 tube on the Super Champ ?

http://el34world.com/charts/Schematics/files/fender/Fender_champ_super.pdf (http://el34world.com/charts/Schematics/files/fender/Fender_champ_super.pdf)


about triple tubes in one bottle ........ give a look here  :smiley:

(http://www.mif.pg.gda.pl/homepages/frank/short/001/6/6AF11.gif)

datasheet
http://www.mif.pg.gda.pl/homepages/frank/sheets/123/6/6AF11.pdf (http://)

on this link a project
http://solorb.com/elect/musiccirc/squirrelmonkey1/ (http://solorb.com/elect/musiccirc/squirrelmonkey1/)

(http://solorb.com/elect/musiccirc/squirrelmonkey1/SquirrelMonkeyR1.jpg)


! No longer available (http://www.youtube.com/watch?v=8YFqkp_JocQ#)

Ciao

Franco

Title: Re: In wich amp was used the Duette Ampeg Preamp ? (that uses a 6SJ7 as optional)
Post by: shooter on June 15, 2016, 09:16:30 am

Quote

the 6C10 tube

Yup, 6BK11 to 6C10, to schematics, crossed eyes.........It's a new day now,
I'm just gonna play outside :icon_biggrin: (for now)

Title: Re: In wich amp was used the Duette Ampeg Preamp ? (that uses a 6SJ7 as optional)
Post by: Paul1453 on June 15, 2016, 06:41:49 pm

I recently got a Wollensak (3M) R-R with one of those triple tube compactrons in it.

I forgot which, maybe a 6C10.

Interesting you have EL37 output tubes.
I haven't run across any of those.
I'll have to check it's data sheet.    :dontknow:

I only find a data sheet for a Mullard EL37.
It seems like a very nice tube!
69 W PP at 400 V fixed bias with 2.5% distortion.
Probably rather rare, high quality, valuable tubes?

Title: Re: In wich amp was used the Duette Ampeg Preamp ? (that uses a 6SJ7 as optional)
Post by: PRR on June 15, 2016, 10:24:02 pm

EL37 wasn't anything so special. It was good for HIGH power, which was not often needed, and it wasn't cheap. It may have only been used in a dozen designs.

EL34 is very much the same idea, made cheaper, heavily promoted, and came about the time that high power amplifiers began to sell well.