Tube boost + overdrive running off a 9 volt battery

[JRM]

There she is, my PSU:


Caps are 100uF and 470uF 25V The schem is dead simple: 15V@200mA Trafo to DB102 rectifying bridge, 100uF Cap in parallel, 7812 voltage regulator and 470uF Cap in parallel at exit. As I wanted to have 12,6V I've added a 4001 diode between the 7812 and the ground. Already tested without the diode and it's the same. What's driving me nuts it's that the 9V that doesn't hum is the one on the right, the parts and schem are the same except the trafo (12V@375mA) and the regulator (7809).

And my Valvemaster:

The disconnected wire is the LED ground in a desperate test to discover what is causing hum. It's not the led...
Ground is not in a perfect star grounding but almost: a wire goes directly from the power jack to the valve socket (pin 5) and another to the input jack where the other ground connections needed go...

[duck_arse]

jrm - on your humming trafo/reg combo - can you put your audio probe to the DC into the reg, and then the DC out of the reg? does either point humm?

and what is the measured DC voltage into (and out of) regulator on the humming combo?

[Jdansti]

I agree with Duck's advice.

The Fairchild data sheet shows a o.33 uf cap on the input and a 0.1 uf on the output. I've seen examples where you have two or more caps on each end. There's a reason for this, but someone else smarter than I will have to explain it.

I would experiment with smaller caps in parallel with the other caps and see if that helps. See if you can temporarily hold the leads of the smaller caps against the leads of the caps on the board to see if that makes a difference. Be careful not to cause a short across the caps if you do this.

If this doesn't work, maybe breadboard or knock up a new circuit using smaller caps. Someone else should be able to chime in with more advice on the caps.

[JRM]

DC voltage before the regulator (no load/full power)= 33.8V/14.8V
DC voltage after the regulator (no load/full power)= 11.95V/11.8V

I think the problem is that the no load condition ruined my first filtering cap! It has a 25V rating and got a much higher voltage that ruined it. I've tried to put several caps in parallel with the out cap and no improvement achieved but a 220uF 50V cap reduced the hum and was just being hold in my hand, not soldered.

[Finom1]

It appears Matsumin's site has gone 404'd on us, but here is my redrawn schematic with a few cap substitutions.

He moved his site recently to a new address http://www.matsumin.net/

Thanks for the schematic! Looks like fun

Hi, I need help, I can not find any schematics. I do not know where it is located.

Can someone send me a direct link to the schematic or just post a pdf of it?

Thank you.

[duck_arse]

it's only 181 pages to look thu, finom, don't you have any spare time?

here is "a" version of the circuit, modified from the beavis diagram. I take no responsibillity for its accuracy.

[vigilante397]

it's only 181 pages to look thu, finom, don't you have any spare time?

here is "a" version of the circuit, modified from the beavis diagram. I take no responsibillity for its accuracy.

The diodes are the only thing added there, other than that it's the original schematic.

[JRM]

It's rockin'!!! I've replaced the 100uF/25V on the PSU for a 220uF/35V and the hum was gone. Now I can fine tune the beast. I might switch again that first cap to a bigger 1000uF (must buy it) as I saw on Tube Town's Banana Booster and/or the second cap to a 2200uF sitting at my parts drawer.
Regarding the pedal's sound I dig it! I'll add a resistance between the gain pot and ground as I don't like that the first half of the travelling adds so little boost/gain (it's a log pot but...). I'm thinking of adding a 50 to 75k resistance in order to set the minimum gain. Another twicking is the tone stack: never liked it much but don't know what fit's better in this circuit: either a Stupidly wonderful tone control (MH original or Jack Orman's variations), a Big Muff tone stack or something else. Another idea is to change the place of the tone control from the exit to before the gain pot as it might affect the tone more effectivly.
Time, I need time!!!

[stallik]

Or, better still, remove the tone control completely. On each of my builds it was superfluous and removing it gives you a little extra something

Glad you've got yours working

[gikai]

Hi everybody!
Before all I need to sorry, because my English is very bad , but I think that everybody can understand me.
I build Valve caster on USSR 6n23p tube. But when I try to check and connect my phone to IN and press "play" I don't hear anything on out(connected 8ohm, 0.5 W speaker! Its only 0.26V on OUT. Please help me!!

[vigilante397]

Hi everybody!
Before all I need to sorry, because my English is very bad , but I think that everybody can understand me.
I build Valve caster on USSR 6n23p tube. But when I try to check and connect my phone to IN and press "play" I don't hear anything on out(connected 8ohm, 0.5 W speaker! Its only 0.26V on OUT. Please help me!!

Which layout did you use? Pics of your build? Are you running the valvecaster into an amplifier or just trying to run it straight into a speaker? If you're plugging your phone into it how do you have it hooked up?

Welcome to the forum by the way

[Jdansti]

I think he meant phone jack which is an old name for the 1/4" guitar jacks we use. They were originally used for phone switch boards.

It sounds like he's running the output to a speaker.

[vigilante397]

I think he meant phone jack which is an old name for the 1/4" guitar jacks we use.

But he said "connect my phone to IN and press play," which leads me to believe he's trying to use it as a stereo amplifier.

Clarification gikai?

[Jdansti]

I interpreted "press play" as pressing the stomp switch. I'll shut up now and let him speak for himself.   

[gikai]

I'm sorry, because I show myself like a stupid
I forget, that tubes have high output impedance. When I connect output to headphones I hear "Sweet victory" in my head! It works (my first working project ). I near time i will post 3D printed box for Valvevaster
I did not think that someone will respond at all to my cry for help , lol

[Jdansti]

There are no stupid questions here!  Glad it works!  Looking forward to seeing your enclosure.

[cranedewd]

Would it be possible to add a balanced line out to this circuit? That way I wouldn't have to use a di box.


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[cranedewd]

So I built this pedal last night. It sounds good but I have a few issues. The tone pot is backwards, can I just solder to the other pin?  Also there is a grounding issue I think. As soon as I touch the box, it goes away. Here's a pic of the build too.


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[Jdansti]

Regarding the tone pot, yes, move C3 to the other outer lug.

Regarding grounding, are you using plastic I/O jacks?  If so, connect a ground wire directly to the enclosure.

[cranedewd]

One more issue. This thing has a nasty hum. As long as your playing its ok but stop and it's overwhelming. I've read some earlier posts about the same hum, but they are mentioning caps that my pedal doesn't have!  I have built this exactly like the schematic that duck_arse posted earlier except for the diodes. Is this my problem?  Is it maybe the wall wart that I'm using? Any help would be awesome!


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