Valvecaster without tone pot

[cnspedalbuilder]

Hello, I'm planning on building the Matsumin ValveCaster from either this vero layout: http://tagboardeffects.blogspot.com/2014/01/matsumin-valve-caster.html
...or this direct PTP layout:
http://s47.photobucket.com/user/krinor/media/Valvecasternylayoutmkabler.jpg.html



I've heard demos of the ValveCaster and they sound pretty dark (in a not good way). I was thinking of setting it up to run through the GuitarPCB.com Tone Tweq EQ board, or maybe a Rangemaster-like boost on veroboard. I was wondering how to modify the layout so that you can eliminate the tone pot. Actually, it might make sense to eliminate the tone and the volume, since the booster circuit or Tone Tweq can take care of the tone and volume. Any ideas?

[rutabaga bob]

Go to the layouts gallery link at the top of the page, and search for Valvecaster...Renegadrian has some vero's with no tone control (see his pages in the gallery).  If the sound is too dark for your taste, consider using smaller input and output caps as well, and see what you think.

[stallik]

A lot of what the valvecaster does is linked to the amp. If you're using the pedal as a true overdrive to force the amp into its own preamp breakup, the result can be dark as the lower frequencies can be more effected than the highs. As a result, many leave the tone full up all the time. I've built both and haven't heard a difference in my normal setup however, if I use a bright tele, I need to tone down the treble and there appears to me to be a big difference between using the tone pot and changing the input cap.
Also watch out for online demos of the pedal. I can get really good sound out of my valvies but I can't record it well enough to reproduce the bass frequencies. Even if I could, I'm not sure my pc could play it back accurately. The end result is a pedal that appears to sound pretty poor

[cnspedalbuilder]

Go to the layouts gallery link at the top of the page, and search for Valvecaster...Renegadrian has some vero's with no tone control (see his pages in the gallery).  If the sound is too dark for your taste, consider using smaller input and output caps as well, and see what you think.

Thanks that's super helpful! I was able to find R's layouts and they look great. He/She has 12V as input. Would it be ok to run at 9V or would this require component subs?

@stallik, thanks for the tips!

[GibsonGM]

Well, the filament of the tube runs on 12V, so you need to provide that to the heater...and since it's there, it just runs at 12V

In short, no, 9V won't work...

[cnspedalbuilder]

I think this layout looks good:
http://www.aronnelson.com/gallery/main.php?g2_view=keyalbum.KeywordAlbum&g2_keyword=Valvecaster&g2_itemId=37363


If I want to skip the volume pot and run it right into a separate boost or eq circuit, would I just send C3 minus to the input of the next circuit?

Also, for those who have modded this circuit, is it better to stick the eq circuit after or before the Valvecaster?

[GibsonGM]

Yes, but I would be sure about what the voltage level is with no volume control.   You probably don't want to send more than a couple of volts to your next pedal...which is why I choose to leave volume controls in until I know for sure.

EQ is the same for most (all?) distortion circuits --  you try it before, try it after, see which sounds better to you     The ideal situation would be to have TWO EQ's, so you can do both at the same time! 

I typically EQ after, it is just how I roll.  If something is weird, such as too much shrill high content, I will go in and 'snub' it before a stage that accentuates it.

[rutabaga bob]

Well...the original Matsumoto schematic ran off 9 volts, but I wouldn't.  I always put the idea to folks to use a 9au7 tube, allowing the heaters to run at the standard stompbox power, and use a voltage multiplier for the plate supply.  My 2 cents worth, anyway...

[Renegadrian]

Thanks for citing me, Larry! Now, cnspedalbuilder, do me and yourself a favour, ditch the valvy ckt as I did and use the valvemaster ckt - it is more true to real high voltage tube preamps and it reacts better to low voltage - yeah I always complained about the valvy being too dark, so I followed the valvemaster ckt and got better results...heck, they're so damn easy cks you can try both before you finalize the pedal!!! I like to put a resistor on first triode's pot, you know the pin going to ground - that way you don't kill the signal but you mantain some sound even with pot at 0.

If you want to try something more versatile, you may look at the alembic ckt (whick work sooooo good) and there's another tube ckt floating on the net which is similar, with a james tone stack instead of the regular TMB between the triodes (a la Ampeg). else you may want to look at Fender amps' preamp schems and replicate them (they do sound great even at low voltages) (alembic f2b is like the showman, then you may want to try princeton, or other preamps with just bass and middle, etc)

[cnspedalbuilder]

Thanks for citing me, Larry! Now, cnspedalbuilder, do me and yourself a favour, ditch the valvy ckt as I did and use the valvemaster ckt - it is more true to real high voltage tube preamps and it reacts better to low voltage - yeah I always complained about the valvy being too dark, so I followed the valvemaster ckt and got better results...heck, they're so damn easy cks you can try both before you finalize the pedal!!! I like to put a resistor on first triode's pot, you know the pin going to ground - that way you don't kill the signal but you mantain some sound even with pot at 0.

If you want to try something more versatile, you may look at the alembic ckt (whick work sooooo good) and there's another tube ckt floating on the net which is similar, with a james tone stack instead of the regular TMB between the triodes (a la Ampeg). else you may want to look at Fender amps' preamp schems and replicate them (they do sound great even at low voltages) (alembic f2b is like the showman, then you may want to try princeton, or other preamps with just bass and middle, etc)

@renegadarian, thank you I just pulled up your layout for the Valvemmaster. That does look like an easy layout. Is it a lot better than the Valvecaster (which I've already built)?

You'll have to forgive me but I'm not sure what you mean by "ckt".

You've got a ton of cool tube layouts. One that I noticed was the Vibracaster, which I assume does tube tremolo? Does that circuit do overdrive and tremolo, or do you sacrifice overdrive for the tremolo feature? Would you recommend using that instead of the Valvemaster? I'd love it if I could get tube overdrive and a switchable tremolo from a one-valve pedal!

[rutabaga bob]

ckt - circuit.

[Renegadrian]

@renegadarian, thank you I just pulled up your layout for the Valvemmaster. That does look like an easy layout. Is it a lot better than the Valvecaster (which I've already built)?

You'll have to forgive me but I'm not sure what you mean by "ckt".

You've got a ton of cool tube layouts. One that I noticed was the Vibracaster, which I assume does tube tremolo? Does that circuit do overdrive and tremolo, or do you sacrifice overdrive for the tremolo feature? Would you recommend using that instead of the Valvemaster? I'd love it if I could get tube overdrive and a switchable tremolo from a one-valve pedal!

yeah ckt is for circuit. the vibracaster is a valvecaster plus the tremolo part - the latter uses two transistors to do the job, when depth is at 0, you have a regular valvecaster. It's not a bad circuit per se, but I guess it would be even better to take the tremolo part of the vibracaster and add it to the valvemaster - you won't find a layout of it, but I guess it won't be so difficult to mod a vibracaster layout to valvemaster specs.

[cnspedalbuilder]

@Renegadrian: How would you alter the Valvemaster layout if you didn't want a tone pot? Or would you strongly advise against that idea?

[stallik]

The tone pot grounds the high frequencies. Just leave it out and the circuit works like the tone knob is at max

[suncrush]

So, I looked at the Valvemaster.  Looks like it uses fixed gain on each triode, and the "gain" knob is a volume control between triode 1 and triode 2.  Certainly a viable option.

2 questions--Why the choice to go with much smaller resistors, and what are the caps between the cathode and ground for?

[cnspedalbuilder]

I finally built the valvemaster and have it in my former valvecaster enclosure. The pedal is much less noisy, which is good. Also, it can get LOUD. The only thing is that, even on max gain, it's not as distorted as I'd like it to get.

@Renegadarian (or others): Is there a simple mod to up the gain/tube distortion in this circuit?

Even if not, I can see using this as an "always on" pedal to get more preamp gain. I definitely recommend it.

[GibsonGM]

Lower the supply voltage. But keep the heaters at 12V....

In a tube circuit, the power supply allows for 'headroom'...how far you can swing a signal without it distortion. The more headroom you have, the lower the distortion (in conjunction with a couple of other things...biasing and so on).      Originally, this thing ran on 9V...put it back there, you'll have more drive due to lower headroom.   

You can also try raising the plate resistors to 100k, 220k, allowing for more swing for a given input, altho admittedly we are WELL below anything we can really predict based on load lines.  Might be interesting, tho!

[Renegadrian]

Running a tube at 12V makes a good pedal but hey you can't have your cake and eat it too...you have to compromise somewhere...yeah it gives a good push but the gain will be limited...you may want to try higher voltages, a multiplier or a transformer...

[stallik]

I've always considered the valvecaster best when overdriving the input of a valve amp. Doing this can give you some serious tones and leaves you with amazing control over distortion via the guitar volume pot.
If you're not using a valve amp or would prefer to keep levels more normal - perhaps to better work with their pedals, you could try clipping diodes. I've done this on one of my valvecasters and organised them on a switch so that without the diodes, a resistor is in line with the signal. This is bypassed when the diodes come in so that the volume loss with the diodes is not noticeable.
I know it seems to defeat the whole idea of a valve pedal but it does sound nicely distorted.

[GibsonGM]

Running a tube at 12V makes a good pedal but hey you can't have your cake and eat it too...you have to compromise somewhere...yeah it gives a good push but the gain will be limited...you may want to try higher voltages, a multiplier or a transformer...

GTFO