Tube boost + overdrive running off a 9 volt battery

[JRM]

I have the schematics here: http://img341.imageshack.us/img341/3121/bajarealtubeoverdrivesc.png

[paulyy]

@JRM = I've built the baja tube pedal and its got some hum to it. Its not a bad pedal but I need a noise gate or suppressor to keep it quiet. If you run it thru a clean channel. Its not bad but when you use it to drive distortion, it hums like crazy. My dual valvcaster runs quiet compared to the baja pedal.

[JRM]

Thanks Paulyy! I've already decided to go for the valvemaster anyway.

[cableguy]

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.

Wow very cool. I will build this and post back. I have most if not all parts on hand.

Can you please help me with the value of the capacitors, resistors etc. (I only see potentiometer values on the picture...)

[tasos]

It's all here
http://www.beavisaudio.com/projects/ValveCaster/

[cableguy]

Thx

[Mad Al]

Hi guys! I want to build this circuit as a part of a preamp for recording. Most likely I'll use two ECC 82's (Twincaster). What's confusing me is this; I'd like to use higher voltage supply, minimum 18V, but for the heaters I have to use 12.6V, right? So, I have this 18V transformer. What kind of IC should I use to get 18V regulated for the valves. Also, can I use another IC (or Zenner) in series after that point to get the 12V for the heaters, and which IC would that be?

Thanks!

[iccaros]

you have several options
A resistor to lower voltage, gets hot is good for limited voltage ranges once calculated (voltage-drop/current) and wattage, voltage * current
you could use a Zener diode with the right dropping voltage and calculated wattage. 
a Voltage regulator like a LM317 works well, needs heat sink, works with a wide range of voltage inputs

Merlin has  good write up on tube heater supplies http://www.freewebs.com/valvewizard/heater.html
at the Bottom is well regulated 6.3 supply, and a good rolling supply if you want more flexibility in tubes used. NOTE: 12a*7 type tubes run off 12.6 or 6.3 depending on how they are wired

[tasos]

Or you could use this power supply...
http://www.generalguitargadgets.com/pdf/ggg_bipolar_ps.pdf
Omit the negative supply output and you are ready....(omit d2,c2,c4,rg2,c6)
For 18volt output the chart says 24-30volt transformer,however i got it working using a 18volt transformer once...
I guess you will have to try yourself

[Frances Rhodes]

would it be a good idea to replace the tone part of the circuit by a Baxandall tube circuit?
like this one:


i believe this kind of circuit has to be buffered but i'm not sure.
i have the full paper that i can upload somewhere for anyone to download it if interested!

[texstrat]

I have a question regarding using the 7812 voltage regulator to eliminate the hum when using a 12V PS. I recently built the original VC using this schematic,

I have noted my resistor and capacitor values based on others trial and errors. I have tested a variety of tubes 12ua7 and the 12ax7. Using these R/C values, the 12ax7 sound not bad at all. For testing purposes I am using a Fender Stratocaster with Klein pickups and a Fender 15G amp.

For PS I am using a BOSS red label 9.6VDC 200mA and a Insignia (generic) 12VDC 700mA. Dependent upon which tube I am testing, I will get very little to no hum using the BOSS PS. The Insignia will give me varying levels of hum dependent on the tube being tested.

The 12VDC clearly is the better choice for more headroom, but the 9VDC sounds good as well. I did not change anything on the circuit to switch between 9 and 12VDC, just plug them in.

So, to get to my point. I used Renegadrian's layout, http://www.aronnelson.com/gallery/main.php/v/Renegadrian/regulator.gif.html, to integrate the voltage regulator into my circuit, shown on the above diagram. When I engage the effect, I get nothing but hum, no sound what so ever. I took it out and everything works. So not being the brightest with circuits, what did I do wrong?

Can someone explain to me what the difference is between the above schematic and this one that Beavis put out, http://www.diystompboxes.com/smfforum/index.php?topic=63479.2500, look at post #2509. The main difference is the way the Volume, Tone and Gain are connected in the circuit. It was noted that someone said the schematic I used would not work, but all three potentiometers function as they should.

Thanks,

Patrick

[tasos]

Is the ''head'' of the regulator touching the chasis?
IT SHOULDN'T!
Also is your dc jack plastic or metal?
Hey here is an idea!
Post some pictures!

[iccaros]

would it be a good idea to replace the tone part of the circuit by a Baxandall tube circuit?
like this one:


i believe this kind of circuit has to be buffered but i'm not sure.
i have the full paper that i can upload somewhere for anyone to download it if interested!

I would place it between the stages and up your voltage, or better, use  a dualcaster, this way you will have a recovery stage

[texstrat]

Right now the circuit is not in an enclosure. I have a heatsink on the regulator. Here are some pictures.







So I have the ground leg of the 7812 to ground on the DC jack, in leg to positive on DC and out leg of the 7812 going to lug 4 on my foot switch which is tied to C1 and pin 2. The 100uf is soldered to the ground and in legs of the 7812. Is the out leg for the 7812 good at lug 4, or does it need to be tied in elsewhere?

[Frances Rhodes]

would it be a good idea to replace the tone part of the circuit by a Baxandall tube circuit?
like this one:


i believe this kind of circuit has to be buffered but i'm not sure.
i have the full paper that i can upload somewhere for anyone to download it if interested!

I would place it between the stages and up your voltage, or better, use  a dualcaster, this way you will have a recovery stage

i would try to draw it with eagle cadsoft but i looked for tubes and never found how to add tubes to schematics...  
and also i would replace the penthode by a triode to have a 12AU7 and a 12AX7

[Jdansti]

Well, my thought on this issue is that I dont care about the design of anything - as long as it sound sgreat.
And if you like the sound of an IC before the pedal, why dont you go for it? An all-tube-approach does not help you, if you dont play it because it does not sound as good.

In addition: I think even the hardcore tubers agree, that a buffer behind the tube is needed. The buffer also has an IC... So why not put anotherone in front of the pedal to boost?
And by the way: ICs are still analogue.... so you still would have an "analogue, hand wired tube pedal"...

Dongle: I'm about to start putting a twin Valvecaster together.  I was wondering if you are still using your Valvemaster configuration and if you still like it.  Does the gain behave any differently after you moved it between the 1st and 2nd stages?

[texstrat]

Any ideas about where Vout from the regulator is supposed to be wired with the Valvecaster?

[Zipslack]

A regulator by itself won't give perfectly clean DC, especially if your wall-wart is being "pulled-down" below 12.6 volts (remember, the 7812 will eat up about 0.6 volts).  Try adding a filter cap or two - one before and one after.  Try maybe 10uF and see if that helps.  If so, you can start playing around with values to get the hum to an acceptable level, or eliminated.  It's been a while, but I recall having to add filter caps on mine to help clean things up...even 10mV of fluctuation can cause pretty bad hum.  I think I eventually got mine down to about 2mV ripple before I was satisfied.

[texstrat]

Zipslack my WW pulls 18.15V at the wall so it is sufficient to use with the 7812. What I am trying to do is get it wired properly to my circuit. Ground on the reg goes to ground on the jack, in on the reg goes to positive on the jack, my question is, "Where does the out on the reg tie into the circuit?" I have not had to use a regulator on any other pedal builds so I am a little unsure where to tie in.

[iccaros]

IF you are using a regulator, it becomes your B+, on its output. So ground goes to ground all around, plug + goes to regulator + and output goes to circuit plus.

or................

could connect 18V to the resistors connected to pins 1 and  6, and to regulator +, and out of regulators to the heaters, pin 4, with pin 5 to ground.