Tube boost + overdrive running off a 9 volt battery

[zambo]

nice looking build!!

[Yeahno]

Heh.

The TwinMaster lives.

Just sorted out a blob of solder that was causing troubles with Stage 2.

The sound: It's a little fat on Stage 1, but crisps up nicely with "More" (Stage 2) engaged. The Gain pots make a fair bit of noise when turned, but I suspect that this is "normal" for this circuit. Tone helps tame the highs when More is in play.

The verified circuit, such as it is, is this:


Switching is per my previous post.

Picture to follow. I daren't post an internal shot, and I'd love to be a good enough player to post a clip, but my wiring skills are on par with my musicianship.

Thanks again to Rick Holte, Renegadrian for the original ValveMaster Vero layout, and zambo for helping me wrap my head around the switching.

Time to beat on this thing and see what sounds I can make.

[JRM]

I'm starting the planning for the Valvemaster build and I came across with one doubt:
- What is the transformer power I need? For the specs of the 12AU7 I've calculated 300mA for the heaters + a maximum of 20mA (max. rating) for the anode. Will I be safe with a 350mA@15V transformer (plus a LM7812+filtering caps)?

[Zipslack]

I would say 500mA, minimim.  Most wall warts are very 'inexact' about what they actually put out.  You also lose some power through the regulator.  The wall-wart sagging-out can contribute more noise. I use a 1A supply, but wouldn't go lower than 750mA to make regulation easier.  Of course, it depends on the quality of the supply - good quality with built-in regulation can be lower current.

[JRM]

Thanks Zipslack. I wasn't talking about a wall-wart, I was talking about building my own power supply from a 400mA@15V transformer plus a LM7812 and the filtering caps. Can go for a bigger one but it's heavier and more expensive.

[JRM]

For more current in first stage:
 

rugeb: I can't see almost any of the pictures you've posted!

I've been searching better and I've found at a Philips 12AU7 (ECC82) datasheet that at 12,6V the heater need just 150mA, which made me wonder why is everybody so keen on having a high power source (>750mA).

[rugeb]

rugeb: I can't see almost any of the pictures you've posted!

SORRY... reposted! (ALL PICTURES)

[JRM]

Thanks Rugeb.
Again regarding courrent draw of a valvecaster/valvemaster: I've spoken to a old school electric engineer that is an expert with hi-fi valve amplifiers and he confirmed that the courrent draw of a circuit like this is quite small and we can safely power our valvemaster/valvecasters with a 200/350 mA power supply depending on the voltage we feed the valve heaters (12.6 or 6.3V, respectively). For the guys doing twin or double masters just double your power. This matches with the courrent draw of EHX 2 valves designs, arround 650mA (found in EHX forum).

[iccaros]

I always rate my power supplies at 20% more than what I think the draw will be, I do not like a close match as I have found cheep power supplies that get hot or do not supply their max. So for a pedal with 12v heaters and single tube, where you may draw 160ma, your 250ma would be fine, but in reality those are rare where I live, I see 1a and 500ma all over the place, so I just use those.

[JRM]

You're right Iccaros. As I'm building my psu and I've found 200 and 300 mA transformers, it will be easy to build a customized psu. In fact I'll take the oportunity to build a RG's spyder-like multiple PSU for all my pedal power needs. 

[Zipslack]

Keep in mind, that standalone PCB transformer that is rated to give a certain amount of amps at a certain voltage is basically what you find inside a typical wall-wart.  That's why I recommended you go at least 500mA, because by the time you have some drain/loss from the regulator, you may have a hard time filtering the supply or keeping the transformer cool.  Although, since it is rated for 350 at 15V instead of 12, I think you'll be okay...just watch for heat.

[JRM]

I'm making my final review for the Valvemaster build and I've came across with this:

2. VR1 pin 1 goes to C2, pin 2 to tube pin 7, pin 3 to ground? Other was round: 1 to ground, 2 to C2, 3 to pin 7

3. VR2 pins 2 and 3 are soldered together and the result goes to ground? Other way round: 1 and 2 soldered together and grounded, 3 to C4

2. This is the same as wiring the VR1/Gain pot: 1 to ground, 2 to tube pin 7 (grid) and 3 to C2
3. If we solder VR2 (tone) pins 2 and 3 together and ground it and solder pin 1 to C4 we get Bass on Full CCW (0 resistance between 1 and 2 of the pot will drain treble to ground) and Treble on Full CW, don't we?


I'm thinking of replacing the plate resistances by 200k  trim pots and 1k resistances with 1k trim pots for adjusting the gain to my ears. I think I'll mess with the caps also, specialy C1 and C2.
I've also read that someone placed some small caps in paralel with R2 and R3 but I don't remember with what purpose (and can't find it anymore).

[zambo]

@ Yeahno - Congrats! Yeah scratchy gain pots are normal. Fun pedal though for sure! You should post shots or clips. Its inspiring for people to see!

[JRM]

Finaly breadboard the Valvemaster and it doesn't work at all, only some hum on the amp's speaker
With both Gain and Vol pots on Max, I got the following voltages to ground on the 12AU7 pins:
1: 8,48V
2: -0,503V
3: 0,04V
4: 0 (GND)
5: 12,41V (+)
6: 8,61V
7: -0,509V
8: 2,13V
9: not conected.

Any hints?

[JRM]

Finaly breadboard the Valvemaster and it doesn't work at all, only some hum on the amp's speaker
With both Gain and Vol pots on Max, I got the following voltages to ground on the 12AU7 pins:
1: 8,48V
2: -0,503V
3: 0,04V
4: 0 (GND)
5: 12,41V (+)
6: 8,61V
7: -0,509V
8: 2,13V
9: not conected.

Any hints?

It was a problem of the f*king breadboard!
Now working and... What a sound! I love it. I'll solder it tonight and tweak the trimpot values then to adjust the gain.
I'll add some resistance in series with the gain pot in order to increase the useful range (otherwise with the por full CCW we don't have any gain/sound).
Loved the warm overdrive and cool boost! My amp got LOUD!

Corrected Voltages:
1: 8,35V
2: -0,682V
3: 0,043V
4: 0 (GND)
5: 12,48V
6: 8,77V
7: -0,715V
8: 0,038V

[Renegadrian]

Nice!!!

[VintageVenzi]

Hey guy, I'm new here obviously to build my own stompbox ^^
I stumbled across the Valvecaster on the net and I have enough knowlegde how to build/solder ist but I'm lacking the knowledge for the details :/
As I'm bass player (Rickenbacker 4003 with 12kOhms pickups) I don't think the this setup will be the best tonal one http://www.beavisaudio.com/projects/ValveCaster/ and as the search wasn't so lucky I wanna ask you here what parts should i change to make it bass-compatible? Diagrams would be very helpfull! Btw I wanna use it as extra pre-amp/overdrive pedal ^^

[Jdansti]

Hey guy, I'm new here obviously to build my own stompbox ^^
I stumbled across the Valvecaster on the net and I have enough knowlegde how to build/solder ist but I'm lacking the knowledge for the details :/
As I'm bass player (Rickenbacker 4003 with 12kOhms pickups) I don't think the this setup will be the best tonal one http://www.beavisaudio.com/projects/ValveCaster/ and as the search wasn't so lucky I wanna ask you here what parts should i change to make it bass-compatible? Diagrams would be very helpfull! Btw I wanna use it as extra pre-amp/overdrive pedal ^^

I think that it should be fine stock. It's been a while since I ran my bass through my Valvecaster (I normal play regular guitar), but my memory is that it sounded great.  If anything you might want to substitute a different input cap.  You came to the right place, though, because Renegadrian is a bass player and one of the Valvecaster gurus.  He should be able to help you out.

[The Tone God]

Hey guy, I'm new here obviously to build my own stompbox ^^
I stumbled across the Valvecaster on the net and I have enough knowlegde how to build/solder ist but I'm lacking the knowledge for the details :/
As I'm bass player (Rickenbacker 4003 with 12kOhms pickups) I don't think the this setup will be the best tonal one http://www.beavisaudio.com/projects/ValveCaster/ and as the search wasn't so lucky I wanna ask you here what parts should i change to make it bass-compatible? Diagrams would be very helpfull! Btw I wanna use it as extra pre-amp/overdrive pedal ^^

Hi,

Welcome to the forum!

I would like to point out that cross posting / duplicating posting is frowned upon here. Also when you start a new thread please use a descriptive subject title. "Newbie needs help!" is not appropriate.

I hope you enjoy our community. Good luck.

Andrew

[Renegadrian]

Thanks man! yep I'm a bass player and I did use the Valvy on bass with good results...it boosts in a good way, without being "too much" - that in the stock version, but with no tone control.