Seymour Duncan - SFX-11 Twin Tube Blue

Port · Post by **Port** » 08 May 2023, 15:37

Hi does anyone have the schematic for the Twin Tube Blue SFX-11 or know the differences of components other than the tubes from the SFX-03 schematic . It looks like they use the same pc board.
Thanks PCB.

karul · Post by **karul** » 08 May 2023, 16:46

sfx-03 (6021 tubes)
https://www.unbrokenstring.com/seymour- ... e-classic/

sfx-11 guts (6111 tubes)
https://reverb.com/item/64239061-seymou ... 0217-12-20

Port · Post by **Port** » 08 May 2023, 19:18

Thanks , I have the info on the tubes.
Looking for the SFX-11 schematic to compare with the SFX-03.
I have a SFX-11 coming , when it gets here I'll trace it out and see what the differences are .
Looks like a good platform to mod.

karul · Post by **karul** » 08 May 2023, 19:28

Port wrote: ↑08 May 2023, 19:18 Thanks , I have the info on the tubes.
Looking for the SFX-11 schematic to compare with the SFX-03.
I have a SFX-11 coming , when it gets here I'll trace it out and see what the differences are .
Looks like a good platform to mod.

sfx-03 thread with schematic
viewtopic.php?t=19980

Port · Post by **Port** » 08 May 2023, 20:19

It's the SFX-11 schematic I'm looking for. I've seen the SFX-03 doc and downloaded it.

karul · Post by **karul** » 08 May 2023, 21:01

I know Port, I've put the link for the ones who are reading this thread and don't have the schematic for sfx 03.

Port · Post by **Port** » 08 May 2023, 22:43

Ok! After I get the SFX-11 Blue I'll post what I find .

Klaus53 · Post by **Klaus53** » 12 Feb 2024, 17:22

Hello everybody,
I'm new to the forum, I'm from Germany and I bought a Twin Tube Classic some time ago. So far I'm content with it, but since I'm more into jazz and blues maybe the Twin Tube Blue might be better for me. I know the Blue one uses 6111 tubes with less gain than the 6024 in the Classic version. Asking for support from Seymour Duncan (schematic) they did not want to send me one. Since I'm kind of experienced with tube technology I'd like to modify my Classic stompbox and hope to find more information here.
Does somebody own maybe even both versions and can say more to the differences in sound? The author of some test on the web said that they did not differ very much, and I do not know if modyfying makes a big difference. The support team on the other hand said that there are more differences made than simply having replaced the tubes with less powerful ones.
So if someone has both versions, please let me know how your sound experiences are. Posting a photo of the complete board would be helpful too, I could compare that version with my board, provided the quality is good and shows resistor and capacitor values clear enough.
I do not know if it makes much sense asking for a schematic . . .

So far - thanks to everybody willing to help! Greetings from Klaus in Germany

Klaus53 · Post by **Klaus53** » 07 May 2025, 10:12

Bump . . .

Post by **modman** » 07 May 2025, 16:49

If you're so desperate and sure that this will solve your problems, buy the other version.
There are pcb pictures available above, start by comparing those to pictures of your unit.

Dirk_Hendrik · Post by **Dirk_Hendrik** » 10 May 2025, 11:32

modman wrote: ↑07 May 2025, 16:49 If you're so desperate and sure that this will solve your problems, buy the other version.

This.
And feel free to tell us your experiences and trace a schematic.