Tube boost + overdrive running off a 9 volt battery

[iccaros]

not to jump in or take over, but do you have a voltagemeter or a oscope?
If you have  a voltagemeter can you set it to AC, and measure the signal going to the grids and them measure the voltage after the coupling capacitors? normally when you are getting no gain or not a lot, its because you have something going to ground in the signal chain. Pin 3 and 8 set the voltage the grid will conduct at, so setting it to ground will make it always conduct, which is good for trouble shooting. at 9 - 12v you may get current on your grid so sometimes adding the coupling cap at the input will clean up issue with that, mostly noisy pots on the guitar

The brand of tube does not matter that much in my opinion ( I know sacrilege.. ), at least when it comes to just working, some will sound different, even in the same brand. but any brand 12au7 should work. They are very close to the 12u7 which was made for 9 - 12 volts so they work well in this design. Hope this can help

[Isak]

Hi there.

does any one can say what will be the max V input to the pedal? 5V..7V...10V pp?
I'm asking  cause I built a filter effect and found that If the output of the filter is high and connect it to the pedal the pedal is killing the sound.
It sounds very choked and with low output, rather then that... The pedal killes the reso of the filter, only if I take the reso all the way CW to self osc mode you can hear the reso.
If I turn the input pot of the filter down to 9 o'clock only then the pedal sounds good even amazing I must say, crunchi sound which I love very much.
But...(there always a but) if the input is low then the output will be low as well.
my thinking was that Ill put a resistor or trimmer at the input of the pedal and at the output of the pedal put an amp to amplifi the signal back to the same vol of the filter.
what do you say? Is it a good idea?
If yes, Can you please advice me for simple amp scheme to boost the signal?

BTW this is my effect,
MFOS SVF
MFOS NOISE
MFOS LFO
MFOS AR
MFOS SIGNAL TO GATE
BUGCRUSHER
AND VALVECASTER OVERDRIVE



Thanks in advance for the help.

[esdiezy28]

@ Isak- I absolutely love that setup you have for mounting. I wish I could clearly label my pedals in such a way, usually just get a perm marker and write a couple times over 

[Isak]

Thank you very much for your kind words
I made the design on adobe illustrator and went to a local shop that print on aluminum, it's cheap here so why wouldn't I do that?
I Gusse that for pedals it's not good but for desktop effect it's great

[iccaros]

Hi there.

does any one can say what will be the max V input to the pedal? 5V..7V...10V pp?
I'm asking  cause I built a filter effect and found that If the output of the filter is high and connect it to the pedal the pedal is killing the sound.
It sounds very choked and with low output, rather then that... The pedal killes the reso of the filter, only if I take the reso all the way CW to self osc mode you can hear the reso.
If I turn the input pot of the filter down to 9 o'clock only then the pedal sounds good even amazing I must say, crunchi sound which I love very much.
But...(there always a but) if the input is low then the output will be low as well.
my thinking was that Ill put a resistor or trimmer at the input of the pedal and at the output of the pedal put an amp to amplifi the signal back to the same vol of the filter.
what do you say? Is it a good idea?
If yes, Can you please advice me for simple amp scheme to boost the signal?

BTW this is my effect,
MFOS SVF
MFOS NOISE
MFOS LFO
MFOS AR
MFOS SIGNAL TO GATE
BUGCRUSHER
AND VALVECASTER OVERDRIVE



Thanks in advance for the help.

With low voltage on the tube, I would not push more than 4v and expect anything clean, and that is dependent on your cathode resistor size on your input. your max swing can only be your high voltage. This design is  a boost, so I would put it first in your. Its also low impedance compared to the rest of your devices, which may cause issues.

[esdiezy28]

where in the effect chain are you looking to add a booster at? I can think of several simple options. FET Buffer to a BJT Linear boost, level controlled with a audio pot.

[Isak]

Thanks for replying guys.

I figure it would be less the 5V input cause the filter can handle up to 5V, if its sound choked after the overdrive the it's make sence.
My chain is filter ---> overdrive with on/off switch.
I was thinking to add an input pot/trimmer to the overdrive and at the output of the overdrive to add a boost circuit to the signal back to 5V.
Hope it makes sence.

Cheers.

BTW I'm running the whole deal with 12V

[Isak]

With low voltage on the tube, I would not push more than 4v and expect anything clean, and that is dependent on your cathode resistor size on your input. your max swing can only be your high voltage. This design is  a boost, so I would put it first in your. Its also low impedance compared to the rest of your devices, which may cause issues.

sorry for the newbi question..
By saying cathode resistor did you mean the 50k pot?
I think I can fix the low impadance issue by using a buffer, I could be wrong tho...
I'll buffer it before going to the overdrive by using the advice of the next site..
http://www.eecs.tufts.edu/~dsculley/tutorial/opamps/opamps5.html

If I understand correctly the signal will go through the opamp buffer and the output from the opamp buffer will be a Celt low impadance so that should fix things, right?

[esdiezy28]

stick a buffer from your output to filter input. Vbias with a 1M5 resistor from your 12V+, coupled with a 1M resistor to ground. The 1M5 resistor should drop 7.2V, leaving you 4.8V (very close to the 5V your looking for).

[RoanldJ]

I wonder if the valvecaster would be good in front of a modeler, reduced gain of course, to warm up the sound of amp models ??

[valve999]

Dear all,
Thank you for the contributors to this thread - it's great stuff, and has led me to make the following decisions:

I'm going to make a Valvemaster based on the Frequency Central schematic at http://www.diystompboxes.com/smfforum/index.php?topic=63479.msg819365#msg819365.
I'm going to use the pictorial guide by David Smith (https://picasaweb.google.com/lh/photo/nWmym5pZuB0fEC5P-SPpkQ) to help with the wiring, substituting the valvemaster components where necessary (I'm new to a lot of this stuff, and this picture will help me to interpret the circuits).
I'm going to use http://gaussmarkov.net/wordpress/thoughts/wiring-up-a-1590b/ to help me wire up the 3PDT switch, and http://www.instructables.com/id/Choosing-The-Resistor-To-Use-With-LEDs/ . (I'm sticking all this in, in case it helps other newbies).
I've got quite a few of the components knocking about from old amps, and an old, broken, wah-wah pedal box to use as a (spacious!) enclosure.

I have a budget guitar and SS amp that I am reasonably happy with (solid bodied Yammy Pacifica and H&K Edition Blue 60R), a limited budget, but a hankering after some tube sounds - plus I want a go at making something so cool!

I'm about to start ordering the stuff I haven't got, but before I do, can I ask the esteemed contributors to this forum the following questions:

1. I'd like to learn about what I'm making - is there anywhere you'd recommend to look at the theory behind what's happening in this valve pre-amp circuit. I've spent a lot of time reading this thread, but I would be lying if I said I'd read every page and that I understood it all, and this will be my first project like this since I made a crystal set circa 1980. On the other hand, I'm reasonably intelligent, fine with a soldering iron, and have a multimeter at the ready!
2. For which components are the values really critical, and which just need to be there or thereabouts?
3. Any last pieces of advice?

Thank you!

[Renegadrian]

1. I'd like to learn about what I'm making - is there anywhere you'd recommend to look at the theory behind what's happening in this valve pre-amp circuit.

Valve Wizard is a mandatory site to visit!
Then just study fenders and marshalls, it's a great beginning!
Basically the valve master follows your ordinary tube preamp stage.

[valve999]

Thanks, Renegadrian - heading over there now.

[carboncomp]

Hey guys, been trawling though the tread looking for PCB artwork for the ValveCaster, but couldn't find one? 

[Renegadrian]

Have you ever heard of a thing called google'? 

[Jdansti]

+1. Like a candy store.

https://www.google.com/search?q=valvecaster+pcb&hl=en&client=safari&tbm=isch&tbo=u&source=univ&sa=X&ei=0nI7UY7nM-e32wXWsoAw&ved=0CC4QsAQ&biw=480&bih=268

[carboncomp]

Have you ever heard of a thing called google'? 

+1. Like a candy store.

OK, I kind of asked for that! 

But ignoring the fact "Have you ever heard of a thing called google?" could be applied to 99% of questions posted here, or on any forum!

I was being a little more community focused, and wondering if anyone here had contributed a PCB that had been verified, or tweak with options and documentation. Rather then just grabbing a random layout off google image only to find out there was something better designed or supported within the pages of this thread. 

[Jdansti]

From the forum:

a manual of condensed thread
http://www.aronnelson.com/DIYFiles/up/12AU7-6111_Valve_Caster_Summary_Rev002.pdf
check HUM and NOISE
a bread board layout of original circuit
http://www.beavisaudio.com/bboard/projects/ttb_Valvecaster.pdf
tube cricket
http://www.diystompboxes.com/smfforum/index.php?topic=63479.msg506164#msg506164
boobtube schem
http://juansolo.demon.co.uk/stompage/schematics/Valve%20Casters/BoobTubeSchematicV2.jpg
latest iteration the Valve-master:
http://www.diystompboxes.com/smfforum/index.php?topic=63479.msg819365#msg819365
high voltage
http://www.geofex.com/circuits/+9_to_33.htm
charge pump layout
http://www.diystompboxes.com/smfforum/index.php?topic=71381.msg607779#msg607779

The first link above has several layout options, including PCB. I think that most people just do a point to point build, but maybe someone who's done a PCB with chime in.

[siroky.jan]

hi

i built 9v valve overdrive like there is on beavis audio. (http://www.beavisaudio.com/projects/ValveCaster/MatsuminValveCaster.gif) but output si sooo low, sometimes even nothing when im moving my gear in winter. can you give me advice please? i cannot find here anyone with same problem like i have (sory, i cannot read all pages of this discussion wire, its so long). thx very much for anything

kivi

[toplak666]

God I hope this thread isn't dead yet because I REALY need your help... So I built a doublecaster with 2 12AX7s. Yea, I know 12ax7s are generally frowned upon when it comes to valvecasters but they completely work for me. Kept the circuit pretty standard, only changed a few resistor values. 12,6V for the heaters, 18V for the rest. Now... Here's the catch: When I wire 3 9V batteries in series and run the doublecaster of those, I get a (at least to my ears) HEAVENLY sound. Crunchy crunch tones, saturated drive tones and next to no hum... But ofcourse, with two tubes those batteries wouldn't last 15minutes... So I hooked the circuit up to a 24V trafo through two LM317s (One for 12,6V the other for 18V) with tons of filtering... When I say tons I mean 4 1000µF capacitors infront of the regulators and 2 1000µF capacitors after EACH of the regulators. And i threw in a few smaller value ones for good measure. Hell, I even put a .65µF 250V capacitor I had lying around infront of the trafo... And after all that filtering I STILL get unacceptable amounts of hum! Adding capacitors doesn't seem to help, however removing them adds more hum. Removing just half of the capacitors would make the circuit pretty much useless... So my question is: How do I get rid of the hum? Seeing as how the circuit works perfectly with batteries, the problem must be with the power supply... Even though I filtered the living heck out of it, it seems I've forgotten something... :S

Any help would be greatly appreciated!
Thanks in advance!