Tube boost + overdrive running off a 9 volt battery

[zambo]

This is so funny...I also run a trans tube peavy half stack ( and I have the combo as well ) but I run into the clean side and use a three tube version. It sounds awesome too me.I cant find a better tone right now and I have access to a marshall jcm , 5150, several fenders etc. I just like the peavy the best. Is this weird?

[UKToecutter]

Yes

Very weird

:-)

[snickers_163]

Ok, have it totally dialed in now. Played a small bar the other night. The pre gain was at about 3 and the post at about 8, presence at 8 and t dynamics at about 80%. Valvecaster in the fx loop was: gain at 10, tone at about 6ish, and volume to taste. Bridge pickup cranked on my les paul. Let me say this thing sounded quite a bit like my 5150, and definitely kept up with the other guitarists Classic 50 (4x10). Very impressive. Saved my back not having to lug the half stack!

[zambo]

I dont mean to hi jack the thread but has anyone tried the runoffgroove big daddy distortion into a valvecaster. It is truly a thing of beauty if you like solid state grind ( which i do as well). Simple build and very rewarding. I think it uses a .0068 mf cap and I subbed a .0047 with good results...

[pudelko]

Ive been struggling to get my dual valvecaster to work properly. I did have a working version of the single tube unit but then decided to try and upgrade it.

Heres all the info I can think of, if theres anything else that I can provide that will help in diagnoses please let me know, if all else fails Ill just go back to the single tube and call it a day:

I used this schematic as the basis:


I created my own perf board layout, which I added leads to the different tube pins from the proper points on the perf:


Other notes:
Im using an unregulated power supply, which is why I added the voltage regulator with 100uF cap to the +12V as described in this thread.
All my grounds come together on the perf board, is this correct?
At the voltage regulator there is continuity (beep from multimeter) between my negative (middle pin) and output (right pin), should this be like this?

The voltages at the various pins, I used the main ground on the perf board as the negative lead on my multimeter for all tests:
Tube A:
1> 2.48
2> -0.36
3> 0
4> 0.04
5> 11.6
6> 4.26
7> -0.42
8> 0.04

Tube B:
1> 4.66
2> -0.7
3> 0
4> 0.01
5> 11.56
6> 4.94
7> -2.05
8> 0.015

The problem is that there is an (almost) constant hum as soon as I plug the power in. This hum gets louder/quieter as I move the volume knob. The tone knob does change the tone of the hum. The hum seems to disappear (or at least gets too quiet to be noticeable) when I play the guitar then comes back when I stop. When I am playing the sound is very distorted, sometimes sounding almost like a fuzz effect, or really bad distortion.

from reading this thread I think that its either a grounding problem or a problem with my power supply, if anyone could provide me any help with this it would be great.

Im probably forgetting some other info, If I think of it Ill post. Ill also see if I can record a little MP3 demo a little later

Thanks!

[snickers_163]

I'll bet anything it's the power supply. I first tried mine with an unregulated 9v power supply and it made an awful noise. Bought a regulated supply and now all is good. On a side note, sometimes, even with a regulated power supply, if I have the wall wart too close to the amp I get squeal.

[pudelko]

I think it was the power supply too, Im thinking that it wasnt strong enough for 2 tubes, it is rated for 800mA @ 12V and from what I read the regulator likes more then twelve to start with so it was probably running out of juice.

I rebuilt the single tube one and its working great! The hum is there when I turn it on but it fades away within 2-3 seconds and then its fine.

[zambo]

You should look at renegadrian twincaster vero layout. His stuff always seems to get good results. Power supply is huge too but I think 800 ma should work. Each tube wants about 200 ma. I built a version with 3 tubes and no hum. Used a onespot 9v power supply. 

[trad3mark]

im starting work on a tube od that's kindof running on 9v. Thanks to rick, i'm using a Nixie ps to get 125V for a single 12AX7. Some of you may remember the argey bargey in the pictures thread, but you'll be glad to know, that particular effort has been dismantled and i'll be using the box for a little FX Loop for my KP.

This is going in a bigger box. it's the same size as a Little big muff, or the big muff with tone and wicker, so i'd hardly call it excessively big.

My previous attempt was not unlike a ZVex Super duper, with 2 switches, 2 gain stages and 3 controls. This is a bit more... practical? It still has 2 gain stages, but one is only a little boost, and quite clean. The other is really gritty. So it'll have 4 controls; Boost, Drive, Tone and Volume. Boost is the cleaner stage. It'll be strong enough that if you've a high output pickup, on full, it'll probably just start to clip. Drive on the other hand will go into cutoff and clip at around 40-45%. There's tonnes of tonestacks out there, but i think i'll probably base it on the Big Muff filter. It's nice and easy, and gives a pretty good range.

One of the major problems with the last project was that nothing really was mounted. This time, it's kinda the opposite. I'm just working things out now, but it looks like the board will be mounted to the 4 pots and the two jacks. As for the tube, i'm ordering 10 nice new sockets, and 28 tubes. The 10 sockets are the ones with the rings with screw holes. I'll probably mount one side of the tube to the outer wall of the box, using a small L-Plate, and the other side will be mounted to the top wall of the box, again, with a small L-Plate. I've still got 2 x 12AX7's i pulled from an old philips turntable, but the tubes i'm ordering are old russian 12AX7's (and some mini pentodes ) so i'll try out the russian tubes too.

The only forseeable problems i have so far is time (i'm mega busy with uni at the moment) and ventilation. Where the tube will sit, should i put a hole or two for ventilation? particularly if it's going to be running 125V?

[zambo]

Vent it. I hear even at 9 to 12 volts you should vent the box when they are inside. I was talking to an amp maker about it. He said vent the sides and front if you can. That way no one can spill beer into it. I was just playing in a bar last week that had a leaky tub of ice by my rig and I was real glad to be running at 9 volts. 125 might have scared me to death

[trad3mark]

cool. Cheers zambo. I left my camera in the studio in uni so no pics till monday or tuesday. It'll only be pics of the enclosure, but you can see my mammoth improvement efforts.

[motorhead]

guys, I can hardly understand what's happening.... 12AU7 needs a minimum of 100 V plate voltage, how could it run on 9 V?

read this:

http://www.nj7p.org/Tube4.php?tube=12AU7

I don't believe this valvecaster would ever work with 12AU7

I am looking into building something similar, but I will have to use 100-250 V

[anchovie]

guys, I can hardly understand what's happening.... 12AU7 needs a minimum of 100 V plate voltage, how could it run on 9 V?

read this:

http://www.nj7p.org/Tube4.php?tube=12AU7

I don't believe this valvecaster would ever work with 12AU7

I am looking into building something similar, but I will have to use 100-250 V

That says "Typical operation", not "Minimum operation". You'll see on the Plate Characteristics graph that the X-axis starts at zero, not 100!

[motorhead]

correct

but who can guarantee any liniarity or characteristics in that range? it's probably random

[anchovie]

Nobody guarantees linearity. It's a guitar distortion pedal, not a hi-fi preamp. The lack of linearity with such a low plate voltage is exploited deliberately.

[Renegadrian]

guys, I can hardly understand what's happening.... 12AU7 needs a minimum of 100 V plate voltage, how could it run on 9 V?

read this:

http://www.nj7p.org/Tube4.php?tube=12AU7

I don't believe this valvecaster would ever work with 12AU7

I am looking into building something similar, but I will have to use 100-250 V

Do you really believe that?! Strange, I have built 9 Valvys (at 12V) for me and some friends - they are working so good!!!
So please read people's reports before making silly statements...

[frequencycentral]

   After two and a half years and over eighty pages of this thread we find that all of our many Valvecasters don't work?   

[motorhead]

I'm not saying that, but I suspect it's a matter of chance rather than science. As a matter of fact, I found some 6-7 tubes myself and i will build one

if you look at some of the characteristics, you will not see the line going down until 0V Plate voltage, so 9V is clearly out of range
that's why I would not expect much out of the circuit, maybe experimenting with various tubes I'll get a good sound, but it's more of an experiment than science

[Renegadrian]

modern science is based on experiments...Isn't it?! 
To say, one of the rules of modern science approach is that you must be able to duplicate your "invention" in every moment.
As you can read, The valvy successfully falls in that rule.

[rotylee]

the initial tube was a 12U7 i think
http://www.nj7p.org/Tube4.php?tube=12U7
the "science" looks better with that tube ?