boobtube twin revisited

[juansolo]

No more demons then?
Always been a Boobtoob kinda guy... hotness in and out, great buildin

Had been using them since the usenet days. Not the company they used to be by a long, long way. I'd held on long enough, time to move on to a new ISP and get paid for hosting (original was a server under my TV).

[sonolink]

I can see them now!!
Thanks a bunch mate

[sonolink]

I'm seriously considering building one of these babies for my pedal board

Is there a way to make the output impedance switchable using only one pot? Like "front of amp"/"fx loop" modes?

Would you have any stripboard layouts at all for the PSU and Switch?

Thanks a lot
Cheers
Sono

[sonolink]

bumpety bump....

[juansolo]

I'm seriously considering building one of these babies for my pedal board

Is there a way to make the output impedance switchable using only one pot? Like "front of amp"/"fx loop" modes?

Would you have any stripboard layouts at all for the PSU and Switch?

Thanks a lot
Cheers
Sono

There is a vero layout for the PSU. Doubt we still have the tagboard layouts around for the amp sections, but then they're not hard to do from the schematic.

Generally speaking if you want it to work as a pre or a pedal, the biggest consideration is really the presence (which isn't really presence... but it does that sort of thing), but that's on the boards as a trimmer anyhow. You could always put that on a pot. But that I've always twiddled with depending on how I use them.

The other thing I suppose is the sheer amount of vol on tap. It comes with the territory as it's a tube pre-amp essentially. You could turn it down or use a different pot.

@marauder is a better bloke to point these questions at to be fair, as the tube effects were all his thing.

[sonolink]

Thanks a lot for the info John. I'll experiment a bit and ask Marauder

Any idea where that vero layout could be or what it would be called?

Thanks again!

[juansolo]

https://www.dropbox.com/s/rwf8iz5v7up1kn4/555SMPSv2.jpg?dl=0

Dont forget that link under the board (in yellow) put that in first and test it... I'm sure I could have laid it out more conventionally, but it wasn't meant for public consumption and we've got a PCB for it now so it's not something we use any more.

[sonolink]

Thanks a lot John

Cheers
Sono

[sonolink]

Hi again

I was lucky enough to get hold of the STM800 schem and by looking into it, it looks like a final version of the Boob Tube Twin. The GrindFX site seems to be down and the STM800 PCB out of production.

Can I ask a couple of questions about this project since I can't order the PCB and I'd really like to build it? (and building from scratch is ok for me). My questions are basically related to power ratings and the fuse. If it's ok to ask about the STM800 please let me know

Thanks
Cheers
Sono

[m-Kresol]

I think it shouldn't be a problem at all to ask about it.

Furthermore, while the GCFX site is currently down due to server issues or something, I don't think the STM is out of production. My guess is, it is just sold out atm. Rej, who is the mastermind behind GCFX, has a job in the far north of Canada, with on-off cycles, so this limits his time to restock and keep everything in the shop. You can PM him or any of the moderators (juansolo, marauder, selfdestroyer, jubal...) for news about the STM projects.

[sonolink]

Hello

Sorry for the language barrier. What I meant was "out of stock"

My questions are mainly about power ratings for caps (resistors are 1/4w as far as I know except R5 that should be 1w), and the fuse. This polyfuse what specs should it have?

Thanks a lot!
Sono

[sonolink]

So basically what are the power ratings for the caps please?
Thanks
Sono

[m-Kresol]

in the jcm800 version R4, R7 and R11 are 1W. The rest is presumably 1/4W. 0.6W have the same size and that's what I use in all my builds.
The caps are all film caps, which have high voltage ratings as is. It is surely not necessary to have the voltage of all of them higher than the HV from your power supply because some of them are only in the signal path and won't see the HV anyways. Just to be sure, I would get with high voltage ratings anyways.
if you need the build doc, pm me your email adress and I'll send it over

[sonolink]

Thanks a lot mate!

[sonolink]

Can someone tell me specs of the polyfuse please?  100mA/250Vdc  for instance?

Thanks!
Sono