Tube boost + overdrive running off a 9 volt battery

[Anon]

pin 5 and  6 are connected through the circuit.So, if pin 5 is supplied seperately  there is no intervention at all.If you already gave it a try please let me know your results

I was gonna try this design except I'll wire an LM317 before the 12.6VDC input to adjust the 16V down to 12.6. I can wire the 32V from psu to the 24VDC. looks like the designer changed R2 & R3 but I'm gonna keep those values as same as Matsumi design (220K & 100K) so there is no gain loss

[yoo86]

ah ok.please tell me,what clarity stands for? and C5 by the cathode?

[red_92]

hello!
i'm having a problem (or two)  with my homemade valvecaster and i thought you could help me
firstly...it sounds strange...with gain at max its like some crunch but its not smooth ,its like a "cracking" sound-the tube is an ecc82 RFT (equivalent to 12au7);this sound is more "visible" on the thick strings E,A,and D
secondly...when the tone pot is at the minimum i get a bit of hiss,the hiss dissapeares when i turn the pot at max but i also loose the treble,so i have to find a solution to this problem

[zambo]

smaller value plate resistors give a cleaner boost. The resistor from pin 5 to pin 1 and the other to pin 6 can be disconected from pin 5 altogether. So just the 12.6 to pin 5. the higher voltage will go to the resistors connected to pin 1 and pin 6. That will seperate your heater from your plate voltage.

The gain at max setting never sounds good to me on this design. 3/4 seems to be the real max gain thats usable. The hiss is probably due to the fact that the gain is maxed or you could be overdriving the input to much.

on a regular tube amp in the preamp a bypass cap on the cathode resistor ( C5) helps boost some of the highs by amplifying them more. Some times it works on low voltage designs, sometimes it causes problems. Not sure in this case. Hope this helps.

Oh yeah, when all else fails, suspect your power supply.

[Edalicious]

Regarding the 386 amp, that's the route I'm taking with my wired tube socket thing. Trying to fit it in a small plastic case.

For the questions about using a tube other than the 12AU7, as said earlier, they are higher gain and won't work nicely unless you modify the circuit, I don't know how to do that part.

tubesandmore.com has the tube and sockets, it is the standard 9-pin tube socket you would use for guitar amp preamp sections.

Here is a rough *unverified* wiring diagram for anyone who wants to try it.

Would it be possible, on this schematic, to use a DPDT to switch between two separate gain pots and to switch on and off an LED indicator light? I'm VERY noob at this so I could be wildly off with this but the way I guess it would work is that the two different gains would be running off to ground and the LED would be coming from the 9V then run off to ground too. Would the LED coming straight from 9V (via a resistor of some sort) and running to ground cause problems? Has anyone any idea what kind of current this circuit draws? Would it make any sense at all to run the LED back to pin 5? All advice greatly appreciated! It'd be great to be able to have a pedal with a clean tubey pre channel and a higher gain tubey overdrive channel all in one box.

[eric1123]

Hello everyone, I just want to start off by saying that this project has been consuming my life for the past few weeks, I love it! You all seem so helpful and contributive.
Back to business though, I seem to be having a similar problem as Red_92. I can't seem to get as much gain as i hear in sound clips and youtube videos of the valvecaster (are they just cranking the volume on the pedal so to drive the amp's input to get distortion?). The little crunch that I do get however, sounds very buzzy like a bee. Very flat with no bite. I followed the point to point beavisaudio schematic using original resistor and capacitor values with a removed tone control. I have different R2 and R3 resistors and tried a variety of 12AU7 and 12AX7 tubes with a bit of a difference in gain, but still that flat buzzing sound. It is powered with a regulated 12V with a switchable 9V battery going to the plates for a bit more volume and gain but still not the sound I hear other people getting.

My voltages are:
P1 8.21V
P2 -0.44V
P3 0V
P4 0V
P5 11.9V
P6 8.68V
P7 -0.47V
P8 0V
P9 has fallen out of the socket - its not need anyway right?

If you guys have any ideas on how to get that full, rich, crunchy tube tone, that would be awesome thanks in advance

[BarnyardBill]

if you are fairly confident that you have wired it correctly and that it is working, then I think the next step would be to try a higher voltage.  For me, I like the way it sounds, but I am going to build a voltage pump before I put it into an enclosure.  Also, if you have any good booster pedals, try putting that in front of it.  Other than that, I would look at changing the respective caps and resistor sizes.  Did you try that yet?

Bill   

[Anon]

The resistor from pin 5 to pin 1 and the other to pin 6 can be disconected from pin 5 altogether. So just the 12.6 to pin 5. the higher voltage will go to the resistors connected to pin 1 and pin 6. That will seperate your heater from your plate voltage.

Oh yeah, when all else fails, suspect your power supply.

supplying the power is trickier than I thought. I disconnected the 100K resistor to pin 5 and ran 12.6V to the heater using an LM317 and 32V going to the anodes. all I got was a constant beep tone "boooooooop". The power supply is rated at 700mA  I reconnected the 100K resistor to pin 5 and ran 12V from another psu to the heater and anodes and it worked. I don't think it's the power supply because it works with other devices. I'm stumped 

[eric1123]

if you are fairly confident that you have wired it correctly and that it is working, then I think the next step would be to try a higher voltage.  For me, I like the way it sounds, but I am going to build a voltage pump before I put it into an enclosure.  Also, if you have any good booster pedals, try putting that in front of it.  Other than that, I would look at changing the respective caps and resistor sizes.  Did you try that yet?

Bill   

i have tried doing what others have done - using an 18V or 24V ac adapter into a 7812 regulator and sending the higher voltage to the plates, however I ended up frying the regulator from overheating, even with a heatsink :S I did try your suggestion of putting a pedal in front which gave a more satisfying gain that i liked, but it still has that buzzy sound on the E, A, and D strings. I added a switchable input cap with a 22nf and 47nf and tried a few different caps for C2 which changes the bass response a bit, and i've tried a few different resistors except for R4 as im not too sure what it does. All of which don't really change the actual character of the gain too much. I could however live with the sound of the booster in front, but my plan is to sell these to my friends who don't all have booster pedals of their own, so that makes me wonder if its possible to add a pot that increases the input signal?

[Anon]

for troubleshooting I dumped the LM317, disconnected the 100K to pin 5 again, tried a 15V wallwart to the anodes and kept the other 12V wallwart on the heaters. made sure all the grounds were connected together, including the wallwart grounds. the tube lit up but no signal   I don't understand why I only get a signal when the 100K resistor is connected to pin 5. another strange thing is when the tube in not inserted it reads:
pin 1 - 15V
pin 5 - 12V
pin 6 - 15V

when the tube is inserted it reads:
pin 1 - 14V
pin 5 - 11.89V
pin 6 - 5V  

When I used the 32V supply on the anodes it reads (tube not inserted):

pin 1 - 32V
pin 5 - 12V
pin 6 - 32V  

it reads (tube inserted):
pin 1 - 31V
pin 5 - 11.89
pin 6 - 10V  

so the problem is obviously on pin 6  

[yoo86]

Hello again everybody, built it just now with 12Vdc,2 mono jack (I/O) and 6 contact switch.Volume works , tone variation is hardly noticed, but what bugs me is that gain is not working... As a pot it seems to be working..also connections are checked ...Any ideas?

Here are my measurements   Pin   1  9,75     V
                                                  2   -0,14
                                                  3   0
                                                  4   0
                                                  5   12,6
                                                  6   10,38
                                                  7  -0,36
                                                  8   0,12
                                                  9   6,28

[yoo86]

ok it seems i put a 4K7 pot instead of a 47K...i just changed it..So now gain seems to work as a volume pot.So if volume is max, gain takes it to eleven(spinal tap) no overdrive whatsoever,please help

[BarnyardBill]

my valvecaster is still on my breadboard and I was fiddling with it yesterday after I soldered a nice 3-out daisy chain.  I tried using the daisy chain on the valvecaster and it began to buzz again.  So, after trying a few other wall warts, I concluded that the only one doesn't cause a bad buzzing noise is the 15V Toshiba Laptop Charger.  At least I assume it's for a laptop.  I have a 12V regulator to make sure the heaters dont get any more than 12V.  I just though this might help if anyone is still troubleshooting their valvecaster for loud buzzing or humming.

Next I want to try a higher voltage on the plates.  I am just deciding on some other things before I make an order.

-BIll

[Anon]

oops  found out I made one of the ground connections come loose while I was wrestling with this thing  I finally got it to work. Wow it really sounds great! It has a full warm earthy sound  I use a 12AU7WA tube in it. I noticed the gain pot is scratchy due to DC current going through it. gonna try different cap values before the gain pot to see what sounds best while blocking the DC

[eric1123]

Could any of you possibly make a quick recording of the valvcaster with the Volume unity gain (no boost or cut) and gain knob at full? Just so I could compare and further troubleshoot my pedal? thanks so much

[Anon]

oops   found out I made one of the ground connections come loose while I was wrestling with this thing   I finally got it to work. Wow it really sounds great! It has a full warm earthy sound   I use a 12AU7WA tube in it. I noticed the gain pot is scratchy due to DC current going through it. gonna try different cap values before the gain pot to see what sounds best while blocking the DC

hmmm tried different caps both film and electrolytic and between pin 3 and the gain pot and all it did was attenuate the signal to almost nothing. I wonder if there is a way to block the DC to the gain pot without killing the signal. also the 2n2 cap going from pin 3 to ground really brightened up the sound nicely

[yoo86]

Hello ..I am a bit confused..I looked again my measurements.I can't get pin 1 below 8.32V.Running it at 12.6 .All other pins are as the ones stated correct.

R1 is 890K , R2 270K and R3 47K .You can notice the gain now a bit (little bit).I tried changing R2 values..Trim pot @ 1M  gave pin 1 7,36V...Went up to 2,2M and as a result i had 5,46V at pin one but no gain.I ended up putting a 270K , close to the schematic reference.Connections quadchecked , so are all components.Can please someone give the noob an explanation?Sorry for bad usage of english language. 

[BarnyardBill]

Could any of you possibly make a quick recording of the valvcaster with the Volume unity gain (no boost or cut) and gain knob at full? Just so I could compare and further troubleshoot my pedal? thanks so much

http://www.youtube.com/watch?v=rgSLIworWSQ  

this is just me messing around.  I cant remember how high the gain was, but probably about halfway.  Also, a fuzz pedal is in there too.

Also,

check out this:   http://www.youtube.com/watch?v=HveUY7eivfI&feature=related

[ultran8]

i dont know why people stick to the 12au7. im runin mine with a very used 12ax7 and it still will be a clean boost but it will get sum drive into it that sounds like a cranked princeton . i also found if u use used up tubes that have ran hours on an amp that it runs better than a new tube. its just seems more broke in and is more effficient to be ran on 9 or 12v. i used all orange drops on mine and built to be pretty much what u would find on a turret board old preamp section instead of treating it like a transistor stylized circuit. it loves being the last in the signal chain. love it . all hail matsumin!

[Anon]

i dont know why people stick to the 12au7. im runin mine with a very used 12ax7 and it still will be a clean boost but it will get sum drive into it that sounds like a cranked princeton . i also found if u use used up tubes that have ran hours on an amp that it runs better than a new tube. its just seems more broke in and is more effficient to be ran on 9 or 12v. i used all orange drops on mine and built to be pretty much what u would find on a turret board old preamp section instead of treating it like a transistor stylized circuit. it loves being the last in the signal chain. love it . all hail matsumin!

some people built twincasters with a 12AX7 as the second tube that can be switched in/out of the circuit. thats what I plan on building next