Tube boost + overdrive running off a 9 volt battery

[suncrush]

I think the general concensus is that 12ax7's don't work as well but my experience is that old ones do. Brimar, Mullard etc sound pretty good but newer valves really need higher voltages.

Agreed. I've tried older Mullards that still sound good, but I've tried brand new Sovteks and JJ's that sound awful.

JJ does a terrible job of doing tube burn-ins.  Their 12AX7's sound terrible in everything until you've run them about 10 hours.

[cranedewd]

You guys have been really helpful and I appreciate it. Next question. If I have a 3pdt switch can I use it as a standby switch with the LED circuit?  If so, where  do I put the switch in the circuit?  One more, is it necessary?  Thanks in advance.


Sent from my iPhone using Tapatalk

[suncrush]

You want an LED that lights up to tell you the unit has power, and another to tell you the drive circuit is engaged?

[cranedewd]

The LED is not really necessary. Could I just use that part of the switch as a standby switch. If I could keep the LED too that would be cool but not the biggest deal if not. I guess the thing I need to know is where would I put the standby in the circuit?


Sent from my iPhone using Tapatalk

[suncrush]

The LED is not really necessary. Could I just use that part of the switch as a standby switch. If I could keep the LED too that would be cool but not the biggest deal if not. I guess the thing I need to know is where would I put the standby in the circuit?


Sent from my iPhone using Tapatalk

By standby, do you mean bypass?

The way you wire these, the heater circuit on the tube is not switched.  If the pedal is plugged in, the heater is on.  You use the 3PDT switch to switch between effect and bypass, and between LED on and off (or if using 2-color LED's, which is not common, between color 1 and color 2.)

[cranedewd]

I meant standby. I know tube amps have standby switches, just wondered if this needs one too.


Sent from my iPhone using Tapatalk

[duck_arse]

I think, if you search PRR's posts for the last couple of months, or maybe in this thread even, he gives some of the reasons for 12AX7 being not best suited to this type low-volts circuit.

[edit :] here and here:
http://www.diystompboxes.com/smfforum/index.php?topic=103881.0
http://www.diystompboxes.com/smfforum/index.php?topic=112782.0

[suncrush]

I meant standby. I know tube amps have standby switches, just wondered if this needs one too.


Sent from my iPhone using Tapatalk

Oh, ok.  No, they're not usually built with one.

The standby on an amp turns on the heater circuits of the tubes, while disengaging the audio circuit.  This prevents wear-and-tear on the power section of the tubes.

In practice, the benefit is infinitessimal.

It's not necessary here, because the tube life of 12A_7 is very long, and the power you're supplying to the power section is not substantial.  Typical service life is nominally in the ballpark of 9000 hours.  Even with the suboptimal build, running the heater at 9V, you'll get more than half of that.  You could play over an hour a day and only have to change tubes once every two years, at most.

[cranedewd]

Last night I took this pedal to band practice at church. I ran through a volume pedal to the valvecaster then to a direct box. I play bass so I am really just kinda looking to use this for a good tube sound. There wasn't nearly enough signal. We use in ear monitors and with the rest of the band playing I couldn't barely hear myself. Should I use a signal boost?  I've seen a couple people that used 2-3 tubes in a valvecaster pedal. Is this what I should do?  Thanks


Sent from my iPhone using Tapatalk

[suncrush]

Last night I took this pedal to band practice at church. I ran through a volume pedal to the valvecaster then to a direct box. I play bass so I am really just kinda looking to use this for a good tube sound. There wasn't nearly enough signal. We use in ear monitors and with the rest of the band playing I couldn't barely hear myself. Should I use a signal boost?  I've seen a couple people that used 2-3 tubes in a valvecaster pedal. Is this what I should do?  Thanks


Sent from my iPhone using Tapatalk

Ok--question 1--Are you getting a volume drop, or just not much boost.

Question 2--Did you use the default capacitors?

[cranedewd]

I'm not sure about a volume drop. Yes I used all default caps.


Sent from my iPhone using Tapatalk

[suncrush]

Well, the pedal is designed for guitar, so the caps are chosen for that frequency range.  I'd have to math it out, but I suspect that your 47nF caps may all need to be larger.  If I get a chance to do said math today, I will, but that could be problem #1.

Do you have a guitar you can try the pedal with?  If so, let us know if works as desired.

[cranedewd]

Yes I've played a guitar through it and it seemed to have plenty of signal. The bass I'm playing is a 5 string Schecter with a preamp if that helps.


Sent from my iPhone using Tapatalk

[cranedewd]

I let a guitar player friend of mine borrow this pedal to get his opinion of it. He says that he wasn't getting good lows or mids.  I built it exactly like the schematic said. What caps would I change and what would I change them too? 


Sent from my iPhone using Tapatalk

[PaulBass]

anybody know how to make a 60 volt power supply with a voltage divider for 12 volts to power this?

[rutabaga bob]

It's mostly been done the other way 'round - 12 volt heater supply with a voltage multiplier or charge pump arrangement to boost voltage for the plates.  Do a search for them...Renegadrian did a voltage multiplier or two, and I think Frequency Central posted a charge pump layout.

[PaulBass]

anybody know how to make a 60 volt power supply with a voltage divider for 12 volts to power this?

how is the noise on those charge pumps? any hums or hissing?

[PaulBass]

found it much easier to tap into the secondary 52 & 12v power of the amplifier with 2 conductor shielded cable. problem solved 

[Wag]

Time to give this incredible thread a bump... and a little recognition. Many thanks to everyone that has contributed to this project. I mean.....like...... WOW!

I dont know how the valvecaster eluded me for so many years. I first "discovered" it only a few short weeks ago and I bet I hadnt even made it 10 pages deep into this thread before deciding I needed one and ironically, I completed the valvecaster AND this thread right about the same time.

I definitely want to explore a few of the valvecaster variations ive read about here but decided to stick to the basics for this first build. I eliminated the tone control and added the treble bleed cap to the gain pot but everthing else was by the book. It was a fairly easy build and it fired up on the first try with an RCA 12au7 installed.

How does it sound?

I own two of the most infamous "clean" amps known to mankind... One is a 68 Bandmaster and the other is a 78 Twin. The VC matches up to them both very well. VERY well...

Then I tossed in my Aqua Puss clone and NPN boost....

Unreal.

[Renegadrian]

anybody know how to make a 60 volt power supply with a voltage divider for 12 volts to power this?

how is the noise on those charge pumps? any hums or hissing?

In the 40106 one, nothing bad to report - in the 555 smps, it depends on many factors, like type of inductor, type of 555 ic, etc. - I built a couple and one type of inductor (the green "resistor-like" type) just burned in a few moments - the black "electrolytic-like" type seems stronger. as you americans say, your mileage may vary.

Renegadrian did a voltage multiplier or two.

I have to be honest on that, I just made some layouts I posted and shared here but the projects they come from are not mine. I always give credit on my images where needed.

Yes I've played a guitar through it and it seemed to have plenty of signal. The bass I'm playing is a 5 string Schecter with a preamp if that helps.

I sometimes used a toneless valvy with my bass, got good results with it, I tell you I prefer to use it with bass than with guitar. It always gave me a good boost both in volume and in "air", fat sound garanteed. maybe it doesn't match well with the bass internal preamp!?