boobtube twin revisited

[sonolink]

Pretty bump...

[sonolink]

Ok sorry I have noticed only now that it's marked on the Boobtube schem. It's a 50mA polyswitch.
I was looking for it on the PSU vero instead.
Cheers
Sono

[sonolink]

Hi again

I've been trying to get in touch with Grind Customs with no luck.
I'd like to ask: There doesn't seem to be a primary power switch anywhere on the scheme. Wouldn't it be a good thing to implement? I know it's all contained inside a box and the input is going to be 9v but I've seen a similar project and it had such a switch. Did you discard it for a reason or simply didn't consider it or thought it wasn't really necessary?

Thanks
Cheers
Sono

[juansolo]

Didn't consider it necessary. Running at this voltage they should last forever (relatively speaking).

[sonolink]

Excellent. Thanks John!!

[sonolink]

A couple more questions please ...

I was thinking of implementing a "Clean Channel" like so:



Would you use another Opto switch for that to prevent noise etc, or a simple 3PDT would do? (I'd like to have an LED to signal which channel would be in use).

The last switch is my attempt to allow for a "in front" or "in loop" use. After some testing it would probably be a fixed resistor or an internal trimpot. What do you reckon?

Thanks for your help and time
Cheers
Sono

[sonolink]

I have redesigned the previous schem like so:



Basically there are 4 switches for:
-FX on/off
-Clean Boost/BoobTube
-BoobTube Twin/BoobTube Twin
-Impedance selector for front of amp or FX loop

Do you think it's a good idea to use Opto switches for each switch to prevent noise?
Any blatant mistake? Any suggestions?

PLEASE all your input is very much appreciated.
Thanks
Sono

[juansolo]

I'm no expert on this, but I expect you'd want to put sw3b before v2b. Also I suspect you'll want to ground the input of the gain stage that's not in use when it's switched out. We've done this before in the dark distant past but I can't remember for the life of me how we did it and the schematic for it will be long gone. Cleggy's (marauder) the valve man anyhow, so I'll get him to take a look at this thread.

EDIT: found a pic of the guts of the one we did. It had a clean/dirty switch.

Busy inside!



Prettier outside...

[juansolo]

Not sure about the optoswitches, you'll have to experiment with those.

I'd move SW3B between V2A and V2B, so that the tone stack is being driven by the cathode follower as a single or twin.


EDIT - That was actually Cleggy responding there... I must have been logged in on his computer.

[sonolink]

Thank you very much for the suggestions John
I will report back soon.

Cheers
Sono

[sonolink]

Like this?



About grounding the input of the gain stage that's not in use when it's switched out, wouldn't that happen automatically with the opto switches?

Thanks again for your help
Cheers
Sono

[sonolink]

Bump

[sonolink]

pretty bump.....

[juansolo]

Thinking about it, you might not need to ground them when not in use. I think I might be getting mixed up with something else. Wouldn't hurt to do it though.

Cleggy rarely sticks his head in here (I have to admit, I'm not as frequent as I used to be), but I'll mention it next time I see him. Can't remember what we did with the Mesa one above (I have an awful memory) and no schems for it so without getting the pedal back from NY (we're in the UK), we're a bit stuck there.

This is why tagboard is your friend with valve effects. We've built loads. Many of which didn't work as well as we'd like and we didn't take any further. We build them on the backs of old enclosures and if they fail, you salvage the PSU and the valve sockets and try again with something else. Best way to figure stuff out is build it and see what happens.

[sonolink]

John

Thanks for your reply. I'll test and try as you say

I just wanted to know if my last schem was correct after your last suggestion (or was it Clegg's logged on your computer?)

I'd move SW3B between V2A and V2B, so that the tone stack is being driven by the cathode follower as a single or twin.
EDIT - That was actually Cleggy responding there... I must have been logged in on his computer.

Here's the schem again. Just let me know if SW3B is now correctly placed please.


I'm nearly ready to prototype
Thanks a lot