SUPERTWIN (RM): converting from SS to a AC3 Twin Top Boost
Moderators: pompeiisneaks, Colossal
SUPERTWIN (RM): converting from SS to a AC3 Twin Top Boost
Hi,
as buddy Karl is very busy at work so he doesn't have time enough at the moment to complete a few things on our projects (see Surrounded by Clones) I took my 1980 Supertwin (RM) I've bought last year. The reverb tank was missing and the sound didn't make me happy either.
This is how it looked after total surgery:
I definitely wanted to use existing material like the NOS PT N50/1 (Engel) from the Sixties and the OT N503S (Socora/Radio Bourse) - a left-over from a 2x 6W amplificateur I made in 1963.
As schematic I used parts of the AC30 TB (NORMAL & BRILLIANT w/o VIB/TREM) feeding a EL84. To get the soft-start of a tube rectifier (EZ80) despite the fact the PT has only 1x 250V I added two 1N4007 to get a bridge-rectifier. Works perfect!
The original chassis has been supplemented with an aluminum profile bar so I had room for the tubes (ECC83 - ECC83 - EL84 - EZ80).
All pots have the same function except Reverb VOL which became the NORMAL volume.
The power supply will be changed a bit - I'm waiting for parts.
Tomorrow I start with the wiring between the socket and the tagboard. There isn't much room so this will be a real challenge (for eyes & hands)!
Mod edit: Fixed image links
Cheers
Claus
as buddy Karl is very busy at work so he doesn't have time enough at the moment to complete a few things on our projects (see Surrounded by Clones) I took my 1980 Supertwin (RM) I've bought last year. The reverb tank was missing and the sound didn't make me happy either.
This is how it looked after total surgery:
I definitely wanted to use existing material like the NOS PT N50/1 (Engel) from the Sixties and the OT N503S (Socora/Radio Bourse) - a left-over from a 2x 6W amplificateur I made in 1963.
As schematic I used parts of the AC30 TB (NORMAL & BRILLIANT w/o VIB/TREM) feeding a EL84. To get the soft-start of a tube rectifier (EZ80) despite the fact the PT has only 1x 250V I added two 1N4007 to get a bridge-rectifier. Works perfect!
The original chassis has been supplemented with an aluminum profile bar so I had room for the tubes (ECC83 - ECC83 - EL84 - EZ80).
All pots have the same function except Reverb VOL which became the NORMAL volume.
The power supply will be changed a bit - I'm waiting for parts.
Tomorrow I start with the wiring between the socket and the tagboard. There isn't much room so this will be a real challenge (for eyes & hands)!
Mod edit: Fixed image links
Cheers
Claus
Last edited by LuciMan on Tue May 26, 2015 9:16 pm, edited 1 time in total.
Re: SUPERTWIN (RM): converting from SS to a AC3 Twin Top Boost
Why are you're leads so long on that one filter cap?
It looks sloppy and is less mechanically stable than a cap with properly terminated leads, more like the cap to the left of it.....
TT
It looks sloppy and is less mechanically stable than a cap with properly terminated leads, more like the cap to the left of it.....
TT
Re: SUPERTWIN (RM): converting from SS to a AC3 Twin Top Boost
Nice project I did the same thing on one of those SS AC4 cabinets it's now an AC15 sort of.
Re: SUPERTWIN (RM): converting from SS to a AC3 Twin Top Boost
Maybe you overlooked this ...tictac wrote:Why are you're leads so long on that one filter cap? It looks sloppy and ...
It will be done properly, but with this provisional PSU I was able to test the amp successfully this night when I completed the wiring.LuciMan wrote: The power supply will be changed a bit - I'm waiting for parts. ...
I enjoyed doing this project very much - the costs were low and the amp sounds nice.M Fowler wrote:Nice project I did the same thing on one of those SS AC4 cabinets .....
The only limitation are these small 5"- 6" speakers - I bet with the AC10 Twin combo i've got here it will sound "bigger"!
Cheers
Claus
Re: SUPERTWIN (RM): converting from SS to a AC3 Twin Top Boost
Hi,
Here are some more pics ...
The original wooden cover at the back won't be used - I'll build a two-piece AC30-like cover. The amp sounds lovely - just like a little AC30. No hum at all although everything is placed quite close to each other.
Mod edit: Fixed links
Cheers
Claus
Here are some more pics ...
The original wooden cover at the back won't be used - I'll build a two-piece AC30-like cover. The amp sounds lovely - just like a little AC30. No hum at all although everything is placed quite close to each other.
Mod edit: Fixed links
Cheers
Claus
Re: SUPERTWIN (RM): converting from SS to a AC3 Twin Top Boost
Wow, this looks awesome!
Would love to hear a sound sample!
This is one of my dream builds, I need to find one of those.
This must look awesome on top of a 2x12 vox cab!
Thomas
Would love to hear a sound sample!
This is one of my dream builds, I need to find one of those.
This must look awesome on top of a 2x12 vox cab!
Thomas
- tubelectron
- Posts: 128
- Joined: Sun Dec 04, 2011 10:33 am
- Location: France
Re: SUPERTWIN (RM): converting from SS to a AC3 Twin Top Boost
Fine job, LuciMan !
Your SuperTwin looks like to be the GrandBrother of my AC3 Top Boost
[img:640:480]http://img10.hostingpics.net/pics/303590IMG_3367.jpg[/img]
[img:640:480]http://img10.hostingpics.net/pics/669128IMG_3368.jpg[/img]
[img:640:480]http://img10.hostingpics.net/pics/148604IMG_3296.jpg[/img]
[img:640:480]http://img10.hostingpics.net/pics/557420IMG_3485.jpg[/img]
A sample, for sound comparison with yours :
https://soundcloud.com/tubelectron/vox- ... 12/s-45eI7
A+!
Your SuperTwin looks like to be the GrandBrother of my AC3 Top Boost
[img:640:480]http://img10.hostingpics.net/pics/303590IMG_3367.jpg[/img]
[img:640:480]http://img10.hostingpics.net/pics/669128IMG_3368.jpg[/img]
[img:640:480]http://img10.hostingpics.net/pics/148604IMG_3296.jpg[/img]
[img:640:480]http://img10.hostingpics.net/pics/557420IMG_3485.jpg[/img]
A sample, for sound comparison with yours :
https://soundcloud.com/tubelectron/vox- ... 12/s-45eI7
A+!
If it works, don't fix it...
www.guilhemamplification.jimdo.com
www.guilhemamplification.jimdo.com
- tubelectron
- Posts: 128
- Joined: Sun Dec 04, 2011 10:33 am
- Location: France
Re: SUPERTWIN (RM): converting from SS to a AC3 Twin Top Boost
@Thomas_H :This must look awesome on top of a 2x12 vox cab!
For my VOX AC3 Top Boost, smaller than the SuperTwin of LuciMan :
[img:640:480]http://img15.hostingpics.net/pics/191194IMG5967.jpg[/img]
A+!
If it works, don't fix it...
www.guilhemamplification.jimdo.com
www.guilhemamplification.jimdo.com
Re: SUPERTWIN (RM): converting from SS to a AC3 Twin Top Boost
Tubelectron that picture is amazing !
it's like a little brother! And it sounds very nice.
Which speaker did you used in it? Is it too small to a 6" or 8"?
it's like a little brother! And it sounds very nice.
Which speaker did you used in it? Is it too small to a 6" or 8"?
- tubelectron
- Posts: 128
- Joined: Sun Dec 04, 2011 10:33 am
- Location: France
Re: SUPERTWIN (RM): converting from SS to a AC3 Twin Top Boost
Thanks Thomas,Thomas_H wrote:Tubelectron that picture is amazing !
it's like a little brother! And it sounds very nice.
Which speaker did you used in it? Is it too small to a 6" or 8"?
I used a NOS AUDAX / SIARE 5" speaker (ref. 12CPPA) that I had in stock (I should have bought more...) which is unfortunately out of production (since AUDAX / SIARE are out of business : a pity !). This speaker has a paper edge, an efficiency of 91.5db and accepts 20W RMS : a true marvel...
The battery switch selects : pentode normal mode, triode mode, pentode with treble attenuated mode.
A+!
If it works, don't fix it...
www.guilhemamplification.jimdo.com
www.guilhemamplification.jimdo.com
Re: SUPERTWIN (RM): converting from SS to a AC3 Twin Top Boost
Thank you very much - your Escort-modification looks nice too.tubelectron wrote:Fine job, LuciMan !
Your SuperTwin looks like to be the GrandBrother of my AC3 Top Boost
How did you manage to realize the input stage & a top boost circuit with just one ECC83?
Cheers
Claus
- tubelectron
- Posts: 128
- Joined: Sun Dec 04, 2011 10:33 am
- Location: France
Re: SUPERTWIN (RM): converting from SS to a AC3 Twin Top Boost
Thanks Claus,LuciMan wrote:Thank you very much - your Escort-modification looks nice too.tubelectron wrote:Fine job, LuciMan !
Your SuperTwin looks like to be the GrandBrother of my AC3 Top Boost
How did you manage to realize the input stage & a top boost circuit with just one ECC83?
Cheers
Claus
I called my amp AC3 Top Boost as a to its big brother the AC30 Top Boost (I had a 1976 model), but it has nothing to do with the Top Boost official circuit, it only can duplicate some of its well-known tone settings.
I think that I may have already posted that schematic some years ago on the forum, but here it is again :
[img:640:450]http://img10.hostingpics.net/pics/66860 ... ematic.jpg[/img]
I wanted to do the same as yours but with a reverb but I didn't found such a well preserved SuperTwin as yours, so I discarded the idea...
A+!
If it works, don't fix it...
www.guilhemamplification.jimdo.com
www.guilhemamplification.jimdo.com
- schaublin65
- Posts: 88
- Joined: Sun Jul 08, 2012 11:59 am
- Location: Ireland
Re: SUPERTWIN (RM): converting from SS to a AC3 Twin Top Boost
Hi,
thanks for posting these really cute amps.
take care..
John
thanks for posting these really cute amps.
take care..
John
Re: SUPERTWIN (RM): converting from SS to a AC3 Twin Top Boost
Hi there,
the AC3 TB SuperTwin did get a nice Upgrade last week!
After testing the circuit ...
... I managed to get more space on the left by moving the four already existing valves to the right including the fuse around the corner ...
... for an additional ECC83 using the AC4-VIB circuit. The ECC83-vib goes to the cathode of the first triode (NORMAL)
The existing tagboard was extended by the testing tagboard. The VIB isn't as strong as the AC15-AC30-VIB but very nice and the SPEED can be set very sensitively. Of course there is a foot-sw too..
There was no need to drill any hole for the speed-pot - replacing the SLAVE-jack socket gave the necessary place. The former slave jack-socket is now the foot-sw-socket (bottom).
In the meantime my buddy Karl had built AC30-like rear panels (still waiting for identical screws ). The metal vents came from my AC30-Combo '78, which now has plastik vents (2 metal vents had to be replaced already in the past so now they look al the same).
Mod edit: fixed links
Cheers
Claus
the AC3 TB SuperTwin did get a nice Upgrade last week!
After testing the circuit ...
... I managed to get more space on the left by moving the four already existing valves to the right including the fuse around the corner ...
... for an additional ECC83 using the AC4-VIB circuit. The ECC83-vib goes to the cathode of the first triode (NORMAL)
The existing tagboard was extended by the testing tagboard. The VIB isn't as strong as the AC15-AC30-VIB but very nice and the SPEED can be set very sensitively. Of course there is a foot-sw too..
There was no need to drill any hole for the speed-pot - replacing the SLAVE-jack socket gave the necessary place. The former slave jack-socket is now the foot-sw-socket (bottom).
In the meantime my buddy Karl had built AC30-like rear panels (still waiting for identical screws ). The metal vents came from my AC30-Combo '78, which now has plastik vents (2 metal vents had to be replaced already in the past so now they look al the same).
Mod edit: fixed links
Cheers
Claus
Re: SUPERTWIN (RM): converting from SS to a AC3 Twin Top Boost
This thread keeps getting better...
You managed to squeeze one more tube in that tiny little amp!
If you can, please make a video. I would love to hear it. It looks awesome.
Cheers,
Thomas
You managed to squeeze one more tube in that tiny little amp!
If you can, please make a video. I would love to hear it. It looks awesome.
Cheers,
Thomas