madbeanpedals::forum

Well I tried to sell it to make the high voltage version and no one wanted it. So it got gutted and rebuilt in it's original enclosure. The outside is the same as it ever was, the insides however, quite a bit different; 190V & 12AX7. Another we're really pleased with. It can go from one of the nicest sounding clean boosts ever to a massive OD. It's also damn near silent.

The optotron was re-used, I really should have cleaned it up...

(http://juansolo.co.uk/stompage/images/btt-i2.jpg)

You guys are artists.

Agreed, but Juansolo has my heart <3

More details:


EDIT: Can't fix these as my schematics folder has gone private. Though again, there are details in the 'making tube pedals' section on the site and Grind do a kit to make all these now.

This looks sweet!  So this pedal runs the tube at requisite high voltage?  That's awesome, if so...  I have always thought tube pedals were false advertising because of the much lower than optimal operating voltage

Yep, we've tried 12AX7s at lower (even 80v) voltages and they just don't work. 190 seems to do the job nicely.

I'll also add, refresh the schematic as I've been editing it a bit. It's right now though.

Got some ideas for re-vamping the Baby Boobtube also...

I recall Merlin (tube dude) saying tubes like the AX7 don't really get in to their stride until they hit 100V.

A nice mod could be to turn the cathode follower in that in to a MOSFET based one and have an extra triodes worth of gain...

We've done that in the past and it's too much in all honesty. It's got more than you'll ever need with three stages.

You underestimate how much I need 8)

Great job mate! Digging that you did it on tagboard.

Been trying to source those damn inductors from Mouser... 26week lead time.... found some on ebay tho, just hoping that they are true to spec.

I feel the need to replace all the 6.66Multipliers in my other tube builts.. 120V sounds lame now... ;D

Could always send you some over. They're not a problem to get here.

Baby Boobtube is going to be a two tube affair next at 190V also ;) Haven't got around to sticking it into DIYLC yet, but I have Cleggy's hand drawn schematic in front of me ;) Hold on, I'll get a camera...

UPDATE: Obv this is subject to change as we haven't built it yet:

I was looking for that schematic.

I've changed it, the cathode followers are now biased for the 190v supply rather than something like 280v.

The tagboard is 2 columns wider than the boobtube twin, so should still fit with the same internal layout.

Thanks John, i'll see how it goes with those from the Bay... grab them from a Canuck seller.. should be more reliable than a random asian seller...

For the new BabyBoob tube, i see that you're putting the 6BR7 as the second gain stage.

From my experience and testing with both circuits, the 6BR7 has lots more gain on tap, got the best results in gain cascading when having it in front of the Boobtube circuit... maybe a flipper switch to switch the order of both gain stage could be handy?

It's the only gain stage. the 12AU7 is being used as a pair of cathode followers.

Quote from: marauder on February 24, 2014, 06:54:57 PM
I was looking for that schematic.

I've changed it, the cathode followers are now biased for the 190v supply rather than something like 280v.

The tagboard is 2 columns wider than the boobtube twin, so should still fit with the same internal layout.

I'll bring it over Weds. Your Kraken has arrived also and the other bits and bobs.

Quote from: juansolo on February 24, 2014, 07:07:38 PM
It's the only gain stage. the 12AU7 is being used as a pair of cathode followers.

Oh! sorry :)

This is an interesting step you are taking here.
I am a little lost with the 1W/2W 10k dimension between Va and Vb.
Is this for safety or how much current do you expect the plates to eat?

Cleggy will have the definitive answer to that one as it's very likely I'm about to be wrong ;) I think it is to essentially decouple the tubes as it's not recommended to have them running on the same feed...

The plates pull very little current which is why we can get away with 190V from 9V. The major current draw is the heaters.

On a JCM800 that resistor is a 2W one, all the others are 1/2W.  Not sure why, but just be safe I used a higher rated one than normal.  A 1/4W would probably work, but the cost of a few pennies, it's not worth risking.

All the other resistors are 1/4W on the pedal.  I think they are 1/2W as they can also take more voltage, 1/4W can typically take 250V according to the specs, and the real amp would be well over 250V at some points.

We played it through the loop return on my Laney today, it's pretty amazing, and very quiet for a highish gain pedal.  It seems the internal layout is good for noise, and I've got an idea for another one after the revisited baby boobtube.

Thanks for letting me know!

It's also usually a flameproof metal oxide resistor.

Quote from: marauder on February 26, 2014, 08:17:52 PM
I've got an idea for another one after the revisited baby boobtube.

I don't know what you have in mind, but a Tube Trem or Comp....would be killer! ;D

Something orange...

anyhow here's a pic of the outside as I had the camera out:

(http://juansolo.co.uk/stompage/images/btt-o2.jpg)

I've seen all those tube pedals that you've build and it would be plesure to watch video of them   :)

Quote from: brejna on March 04, 2014, 07:37:19 PM
I've seen all those tube pedals that you've build and it would be plesure to watch video of them   :)

Today i was thinking of pumping out couple Demo's... i have the BabyBoobTube and BoobTube here... running them directly into the effect return of the amp... it's simply delicious!

And.... Orange.... that's a nice color! :P ;D

Then you have to share those tasty tones with us :D

Does anyone know why I can't see ANY of the links or pics posted on the messages please?

Thanks a lot  ;)

I changed my hosting... I'll fix them, but if you go to the site they're all in tube pedals anyhow.

FWIW, removed 'demon' from the link and they will work (I'll do that now).

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

Quote from: nzCdog on November 12, 2016, 03:10:13 AM
No more demons then? ;D
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).

I can see them now!!
Thanks a bunch mate ;)

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

bumpety bump....

Quote from: sonolink on November 21, 2016, 05:23:30 PM
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.

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!

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.

Thanks a lot John ;)

Cheers
Sono

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

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.

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

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

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

Thanks a lot mate! :)

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

Thanks!
Sono

Pretty bump...

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

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

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

Excellent. Thanks John!! ;)

A couple more questions please ...

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

(https://s12.postimg.org/omdkk9qyx/Pop.jpg) (https://postimg.org/image/omdkk9qyx/)

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

I have redesigned the previous schem like so:

(https://s7.postimg.org/ko52sif3b/Boob_Twin_Switched.png) (https://postimg.org/image/ko52sif3b/)

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

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!

(http://juansolo.co.uk/stompage/images/jcm1-i2.jpg)

Prettier outside...

(http://juansolo.co.uk/stompage/images/jcm1-o.jpg)

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.

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

Cheers
Sono

Like this?

(https://s11.postimg.org/k148mbi1b/Boob_Twin_Switched.jpg) (https://postimg.org/image/k148mbi1b/)

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

Bump

pretty bump.....

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.

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?) ;)

Quote from: juansolo on March 16, 2017, 11:05:23 AM
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.
(https://s11.postimg.org/k148mbi1b/Boob_Twin_Switched.jpg) (https://postimg.org/image/k148mbi1b/)

I'm nearly ready to prototype :)
Thanks a lot

Yeah that's in the right place as per Cleggy's suggestion.

Great!!
Thanks John. I'll keep you guys posted!!!
Cheers  ;)
Sono

BTW, It´s a Hammond 1590BB box you used?

Cheers
Sono

1590XX

A BB would be very snug!

Good thing I asked hehehe!!
Thanks mate! ;)

I'm trying to cut down on things as much as possible since I now have more switches and knobs than the original project. So I'm thinking of customizing a double gang pot to have a single Master knob that depending on SW4 position would act as 1Mlog or 100klog Master output. (It's a matter of swapping wafers basically)

On the same line of thought I'd like to ask: is the Presence knob really necessary? Is it's role rather important?

Thanks :)

Quote from: sonolink on May 05, 2017, 04:20:51 PM

I'm trying to cut down on things as much as possible since I now have more switches and knobs than the original project. So I'm thinking of customizing a double gang pot to have a single Master knob that depending on SW4 position would act as 1Mlog or 100klog Master output. (It's a matter of swapping wafers basically)

On the same line of thought I'd like to ask: is the Presence knob really necessary? Is it's role rather important?

Thanks :)

It can be a trimmer as you only need to change it really depending on what you plug it into amp-wise. If it's always the same amp it can be set and forget.

Great!! I'll definitely go for that then. A trimmer inside will give me more room :)

Thanks John!!
Cheers
Sono

Probably a dumb question but I've been checking the pics of the guts you have posted along the thread and cannot figure out what you use to hold the boards in place!! They look like they're floating held by the cables!! Could you share what you use please? :)

Cheers
Sono

Part of it is the cables as it's all solid core in those builds. But the board is secured to the back of the pots using Scotch tape.

Clever! ;)

Cheers
Sono

Lovely.

I agree about using tubes at higher voltages. They just don't seem to sing otherwise.

I just let the wires hold the board in place too. I was worried until now.

Maybe a dumb question but lately I've been asking myself:

Why a 9v converter? If it needs nearly 2A to work and the best way to feed it is with a separate PSU such as the Truetone One Spot why not have directly a 240VAC input?

Just out of curiosity :)
Cheers
Sono

I would guess it's because standard centre negative plugs and cables are not made for such high voltages. Also, you would need another circuitry internally for heaters.

not to speak of high voltage dangers..

Sorry what I meant is why not going directly from a 240VAC outlet into the pedal and inside the pedal have a PSU converting that into whatever is needed by the effect? After all we're using a One Spot that converts 240VAC into 9v, and inside the pedal the charge pump is converting those 9V into 190VDC and 6V for the effect...

Just wondering... :)
Oh and of course I wouldn't use a standard coaxial DC cable for that... :)
Cheers
Sono

Building a smps to deliver two different tensions is  more difficult than a single one. The noise from one side could affect the other.

You will definitely need a flyback transformer with some odd taps,  which would be difficult to find, or costly.

It ends up being a really complicated design when compared to a single SMPS. Take a look at your PC'S power supply for a better idea.

A simpler approach is using odd tube heaters, which already work at higher voltages like 25v and add them in series. Using a 24v transformer with center tap you can have 48v for heaters and with a quintupler circuit achieve almost 250v.

Would something like this do?

Bumpety bump!

Quite simply because I run my pedals from a 9v DC centre negative PSU. Having multiple psu's is a ball-ache :)

Also, adding a transformer in there would be a significant bump in cost and parts to fit inside. Finally it's really easy to get the 190v from a charge pump as it's low current. The high current feed is the 6.3v or 12v for the heaters (depending on how you run them). So it makes sense to regulate a 9v supply to 6v for those. Or if you set the whole thing to run at 12v it makes it even simpler. It wouldn't really change what the SMPS delivers to the HV side either as 190v is about what it's nice and stable at.

If you want to go to the trouble/risks of dealing with mains voltages in a pedal, you may as well just build an amp, as that's what you're doing at that point.

Right you are. I won't go that way. It was just curiosity :)
Thanks
Sono

Hi again

Sorry for the delay but I got busy with other stuff. I picked up this project again and built the PSU. I use a 1 Spot 9v PSU connected to "9V" and "G" pins of the schem. When I juice it up I read 9v everywhere (Test, HV and 6V terminals).
I've checked the board several times but everything seems correct. Any ideas on what I could be doing wrong?

Thanks in advance for your time and help
Sono

Update: the NE555 went up in smoke :(
Any help troubleshooting very much appreciated. Thanks :)

Cheers
Sono

If you're in the uk you could send it over and we'll take a look at it.

Hi Juan

I sincerely appreciate your kind offer. I live in Spain and it would probably be the easiest thing to do, but with all due respect, I'd like to fight this one myself (with some support and guidance of course)...I like this beast so much I want to make it mine if you know what I mean :)

So I went back to square one, back to strip board and back to Cleggs design, only adding a diode that is on GrindFX schem, one that bridges 9V to ground right at the start. I'm not sure "bridges" is the correct term but I think you get what I'm saying...excuse my language barrier :)

So I put it together this evening and fired it up and get to read 30V. I tweaked the voltage adjuster and POP went the 2.2uF electrolytic (it was the wrong way around). I replaced it and made sure it was the right way now. Fired it up again and now I get 300V!!

The thing is, when I tweak the pot it won't do much. It stays around 300-350V...of course I don't know if it's because something was blown together with the cap or because I placed something wrong...I guess anything is possible. If there's nothing obvious you can think of, I'll check the resistors, unsolder caps, diodes and ICs, check them and try again tomorrow and report back.

Thanks again for everything :)
Cheers
Sono

UPDATE: It works now!! :)
There was a bad connection to the Vol. Adj. Once fixed the PSU seems to be now running smooth and I could adjust it to 190V :)

Cheers
Sono

One more question please:

I am joining the Clegg PSU to 3 Optotrons on a vero. Both circuits original schems have a diode between 9V and GND. I guess I should put only one diode for the whole thing right? Or should I put one diode for each circuit?
Not sure this makes sense....

Yeah you only need one.

Excellent. Thanks Juan!!! ;)

Another couple of questions please:

1-The negative terminal of the DC connector would be the final GND terminal (like the green cable to chassis on an amp)?

2-On GrindFX schem "VA" and "VB" (connected to plate resistors) are connected to B+ (190V) right?

3-I've added True Bypass Switch and Clean/Crunch/Lead Channels to the circuit.
Here's the GrindFX schem:
(https://i.postimg.cc/xJctj52p/STM800.jpg) (https://postimg.cc/xJctj52p)

Here's the same schem with the switches:
(https://i.postimg.cc/kBYWM3gq/Angry-Boy-Hoffman-Tone-Stack.jpg) (https://postimg.cc/kBYWM3gq)

2-should C13 (right after the Master pot) go after SW2.B? SW4 is supposed to allow the player to choose to place the preamp in front of an amp (through 100k pot) or in its FX loop (through Presence circuit and 1M pot)

3-I just realized I won't be able to use the Opto to switch from Clean to "Dirty", right? :(
If so will a regular Stomp DPDT switch make noise when switching and is there a fix for that?

I really appreciate some input on these questions please :)
Thanks in advance for your time and help!!
Cheers
Sono

Hello again,

A question about the PSU, please. If I want to use only one HV terminal (HVBA), can I just delete C7, R5, HVB1 and HVB2 from the schematic?

Thanks! ;)

Quote from: sonolink on July 21, 2019, 11:45:12 AM
Hello again,

A question about the PSU, please. If I want to use only one HV terminal (HVBA), can I just delete C7, R5, HVB1 and HVB2 from the schematic?

Thanks! ;)

Sure, just omit those parts

Thanks!! ;)