BAJA Real Tube Drive pedal project [documentation]

[ToneKarma]

No worries, you might want to increase the value of the resistor till you get about 12.7V AC on pins 4 and 5 of the Tube socket, 14.1V AC sounds a little bit too much heater voltage...

Believe me, I have made much worse mistakes than that, one time I went to switch on my little guitar amp, and it wouldn't power up, it wasn't until I realized my silly mistake, I had forgotten to plug it into the mains socket.....

12.97 VAC with a 47R resistor ... I think I´ll leave it as is.

Goodness, that heater resistor gets pretty hot ...

Thanks mates !
I shall post more when I will have finished the build ... and yes Bajaman ... with pictures!

[DrNomis]

No worries, you might want to increase the value of the resistor till you get about 12.7V AC on pins 4 and 5 of the Tube socket, 14.1V AC sounds a little bit too much heater voltage...

Believe me, I have made much worse mistakes than that, one time I went to switch on my little guitar amp, and it wouldn't power up, it wasn't until I realized my silly mistake, I had forgotten to plug it into the mains socket.....

12.97 VAC with a 47R resistor ... I think I´ll leave it as is.

Goodness, that heater resistor gets pretty hot ...

Thanks mates !
I shall post more when I will have finished the build ... and yes Bajaman ... with pictures!

Personally, I'd be happy with 12.97 V AC on the heater pins, that's only about .27 V higher than in my build, which is nothing to worry about, probably well within tolerance....

i agree, that resistor sure does get hot, I'm using a 5Watt 33 Ohm Ceramic Wirewound type in my build, and it gets pretty hot too, if you're using a 2Watt type, consider replacing it with a 5 Watt so it's not over-dissipating, a 5 Watt 47 Ohm Ceramic Wirewound resistor will fit onto the PCB if you bend the leads right at the body ends, allow a space of about 5mm between the resistor and PCB before you solder it in....

Incidentally, the heat generated by that resistor shouldn't cause any problems for the other components, the 12AX7 tube generates heat as part of it's operation anyway.....

[ToneKarma]

Personally, I'd be happy with 12.97 V AC on the heater pins, that's only about .27 V higher than in my build, which is nothing to worry about, probably well within tolerance....

i agree, that resistor sure does get hot, I'm using a 5Watt 33 Ohm Ceramic Wirewound type in my build, and it gets pretty hot too, if you're using a 2Watt type, consider replacing it with a 5 Watt so it's not over-dissipating, a 5 Watt 47 Ohm Ceramic Wirewound resistor will fit onto the PCB if you bend the leads right at the body ends, allow a space of about 5mm between the resistor and PCB before you solder it in....

Incidentally, the heat generated by that resistor shouldn't cause any problems for the other components, the 12AX7 tube generates heat as part of it's operation anyway.....

It is a 5W resistor, one of those green metal (oxide) ones at 5%.
I soldered it well 5mm above the PCB and I bent the two 22µF caps next to it a bit backwards to keep them "out of the way".

Isn´t it said that heater voltage is best at 12.6V but still considered safe within ±10% ?
So, 12.97V would only be +3%.

[DrNomis]

Personally, I'd be happy with 12.97 V AC on the heater pins, that's only about .27 V higher than in my build, which is nothing to worry about, probably well within tolerance....

i agree, that resistor sure does get hot, I'm using a 5Watt 33 Ohm Ceramic Wirewound type in my build, and it gets pretty hot too, if you're using a 2Watt type, consider replacing it with a 5 Watt so it's not over-dissipating, a 5 Watt 47 Ohm Ceramic Wirewound resistor will fit onto the PCB if you bend the leads right at the body ends, allow a space of about 5mm between the resistor and PCB before you solder it in....

Incidentally, the heat generated by that resistor shouldn't cause any problems for the other components, the 12AX7 tube generates heat as part of it's operation anyway.....

It is a 5W resistor, one of those green metal (oxide) ones at 5%.
I soldered it well 5mm above the PCB and I bent the two 22µF caps next to it a bit backwards to keep them "out of the way".

Isn´t it said that heater voltage is best at 12.6V but still considered safe within ±10% ?
So, 12.97V would only be +3%.

Yeah, I reckon so, you might slightly reduce the life expectancy of the 12AX7 tube cathodes, the electron-emitting oxide coating wears out as the tube is in operation and powered up, over time the electron "emission" of the cathodes reduces, but that usually happens over the course of many years, there's stories of tubes having been in use for something like 40 years and they still had good emission levels, anyway I don't think +3% is anything to worry about.....

Have you tried your build out, and how does it sound?.....

[ToneKarma]

Have you tried your build out, and how does it sound?.....

No, I haven´t.
I have still not found a source for proper jacks.
Everything I find over here is wider as the given dimensions on Bajaman´s PCB. Even bending those little legs won´t help.

The reason why I have opted for an 18VAC transformer is, as 16VAC transformers are around 40,- Euro here and I bought the 18VAC/1.125A wall warts for around 9,- Euro from RS.

Mentioning RS ... I think I have just found the right ones at RS while writing this. Order no. 342-4471
I better buy a few ... just in case.

To be continued ...

[DrNomis]

Have you tried your build out, and how does it sound?.....

No, I haven´t.
I have still not found a source for proper jacks.
Everything I find over here is wider as the given dimensions on Bajaman´s PCB. Even bending those little legs won´t help.

The reason why I have opted for an 18VAC transformer is, as 16VAC transformers are around 40,- Euro here and I bought the 18VAC/1.125A wall warts for around 9,- Euro from RS.

Mentioning RS ... I think I have just found the right ones at RS while writing this. Order no. 342-4471
I better buy a few ... just in case.

To be continued ...

I had the same issue with the in and out sockets that I wanted to use, but I found a way to solder the sockets to the PCB, here's what you do:

1,With a pair of clippers, cut off the thin part of the socket's solder terminals that normally go through holes on the PCB.

2,Cut some Tinned Copper Wire into 4cm lengths so that you have enough pieces for each terminal on the sockets.

3,Carefully solder one piece of Tinned Copper Wire to each terminal of the sockets so that you don't melt the plastic insulation.

4,Thread each wire into it's respective hole on the PCB, and push the socket down so that it sits as low as possible on the circuit board.

5,Turn the board over and solder each wire to it's solder pad.


Hope that helps....

[bajaman]

oh fo f***'s sake buy the proper Neutrik sockets
As I have stated on many occasions , they are Neutrik stereo type NRJ6HF-1 (or the mono version - NRJ4HF-1 will work fine ).
They are easily available online - try Mouser or Digikey Etc.
bajaman

[DrNomis]

Sorry about that Bajaman, I must have missed something along the line somewhere, and wasn't aware that those were the correct type of sockets to use, it was only when I was about to solder my sockets onto the PCB that I'd realized my mistake.....

[ToneKarma]

I had the same issue with the in and out sockets that I wanted to use, but I found a way to solder the sockets to the PCB, here's what you do:

1,With a pair of clippers, cut off the thin part of the socket's solder terminals that normally go through holes on the PCB.

2,Cut some Tinned Copper Wire into 4cm lengths so that you have enough pieces for each terminal on the sockets.

3,Carefully solder one piece of Tinned Copper Wire to each terminal of the sockets so that you don't melt the plastic insulation.

4,Thread each wire into it's respective hole on the PCB, and push the socket down so that it sits as low as possible on the circuit board.

5,Turn the board over and solder each wire to it's solder pad.


Hope that helps....

oh fo f***'s sake buy the proper Neutrik sockets
As I have stated on many occasions , they are Neutrik stereo type NRJ6HF-1 (or the mono version - NRJ4HF-1 will work fine ).
They are easily available online - try Mouser or Digikey Etc.
bajaman

Thanks mates!
Initially I thought about rising the jacks with the aid of wires myself, as I didn´t like the idea to slot - instead of drilling - the enclosure for the jacks (daft aesthetican me... ), but then I thought "WTH ?!" ...

So, I ordered fitting jacks from RS yesterday.

I agree that Neutrik is the way to go ... but ... let´s be realistic, Steve .. they are not as good anymore as they used to ...
A guy at the counter of "Conrad" (a big electronic parts chain store over here, like Radio Shack) agreed with me on this, after asking "Who the hell wants Germanium diodes these days ???".
After measuring forward voltages for 20 minutes with me and ignoring waiting customers, he turned out an experienced valve amp expert who only works there part-time to finance his still simmering hifi valve amp business.

Anyway, this has certainly to do with the global craze to increase profits to ridiculousness.
Why grow and gain profit margins at any rate, while staying where one is and just getting better with time is a much prosperous, lasting and future-oriented concept, that yields a lot more contentment for all involved (incl. customers)?!

Mouser charges 20 Euros shipping costs for European customers. That´s 27.50 AUD or 37.50 NZD. Digikey´s shipping costs are about 10% less.
For a couple of jacks ??

I´ll post a pic and my first impressions of the BRTO asap ...

[DrNomis]

No worries ToneKarma, glad to help out anytime I can mate....

[bajaman]

I use the Neutrik slimline off centre jacks in a lot of my pedals these days - they save a lot of board space particularly when using Hammond 1590B enclosures (and their generic equivalents)
cheers
bajaman

[DrNomis]

The problem is, those Neutrik Sockets are practically unavalible from anywhere in Australia, sure, I could have ordered some online if I wanted to, but I didn't have any money on my Visa Card at the time, so I ended up getting something similar from Jaycar Electronics, the ones I bought did the job fine...

Next time, I might see if I can get some of those Neutriks online.....

[ToneKarma]

Have you tried your build out, and how does it sound?.....

Whoo-hee !
Goodness, that pedal´s middle name is Raaawk!

I have now tried it out with the old National 12AX7 (from the unused ADA MP-1) which gives 12.97VAC at the heaters. Also a TAD (Tube Amp Doctor) 12AX7 @ 12.63VAC and a TAD 7025 @ 12.7VAC.
All with a 18VAC/1.125A wall wart and a 47R/5W heater resistor (which is still a bit smelly while working). I will measure how hot it actually gets this weekend.

At the current setup, it sounds best with the DRIVE up to max. 2 o´clock.
After two o´clock the pedal becomes really grainy, growly, oversaturated which does not sound so nice to me. Perhaps there is a mistake ... ... any ideas to tame the gain?
It is perfect with the DRIVE set between 10 and 1 o´clock, although you can have nice bluesy tones at low gain settings too.

The BRTO is a really sweet pedal and there is no noticable noise in my two builds.
The TONE knob works very efficient and covers all areas.

So far, the 7025 valve sounds best to me, as it is warmer as the 12AX7 and provides more transparency and detail, still with a rich/fat overdrive.

Since I have a second PCB, I will definitely mod this one to fit a 12AU7 valve.

To be continued ...

[DrNomis]

Have you tried your build out, and how does it sound?.....

Whoo-hee !
Goodness, that pedal´s middle name is Raaawk!

I have now tried it out with the old National 12AX7 (from the unused ADA MP-1) which gives 12.97VAC at the heaters. Also a TAD (Tube Amp Doctor) 12AX7 @ 12.63VAC and a TAD 7025 @ 12.7VAC.
All with a 18VAC/1.125A wall wart and a 47R/5W heater resistor (which is still a bit smelly while working). I will measure how hot it actually gets this weekend.

At the current setup, it sounds best with the DRIVE up to max. 2 o´clock.
After two o´clock the pedal becomes really grainy, growly, oversaturated which does not sound so nice to me. Perhaps there is a mistake ... ... any ideas to tame the gain?
It is perfect with the DRIVE set between 10 and 1 o´clock, although you can have nice bluesy tones at low gain settings too.

The BRTO is a really sweet pedal and there is no noticable noise in my two builds.
The TONE knob works very efficient and covers all areas.

So far, the 7025 valve sounds best to me, as it is warmer as the 12AX7 and provides more transparency and detail, still with a rich/fat overdrive.

Since I have a second PCB, I will definitely mod this one to fit a 12AU7 valve.

To be continued ...

I get that grainy, growly, over-saturated effect when I turn the drive up past 2 O Clock too, it's a characteristic of the design and not a fault, to tame the gain, you can try increasing the 680 Ohm resistors to something like 1k, or maybe 2k2, this will reduce the maximum gain of the opamp when the drive control is set to maximum....

I've found that 12AX7, 12AT7, and 12AU7 tubes will all work in this design....

Hope that helps....


I've got a Sovtek 12AX7WA/7025 tube currently installed in my build, and it sounds pretty good, I went through all my tubes and tried all my 12AX7s, my 12AT7, and my 12AU7A, two of my 12AX7 tubes made barely any sound, so I think that they're no-good at all, a couple of other 12AX7s were very low on gain, but the rest of them were fine....

[bajaman]

After two o´clock the pedal becomes really grainy, growly, oversaturated which does not sound so nice to me. Perhaps there is a mistake ... ... any ideas to tame the gain?
It is perfect with the DRIVE set between 10 and 1 o´clock, although you can have nice bluesy tones at low gain settings too.

THERE IS NO MISTAKE
But perhaps you have answered your own question with the last sentence - turn the gain control down
The higher gain settings with tone control adjusted towards the bassier end will get you into "American Woman" territory
Incidentally, your favoured settings are precisely the same as I use on my pedal board.
Try and obtain a 16vAC power pack if you can - and yes that 47 ohm heater dropper resistor will get VERY hot with the additional uneccessary 2v AC supply
cheers
bajaman

[DrNomis]

After two o´clock the pedal becomes really grainy, growly, oversaturated which does not sound so nice to me. Perhaps there is a mistake ... ... any ideas to tame the gain?
It is perfect with the DRIVE set between 10 and 1 o´clock, although you can have nice bluesy tones at low gain settings too.

THERE IS NO MISTAKE
But perhaps you have answered your own question with the last sentence - turn the gain control down
The higher gain settings with tone control adjusted towards the bassier end will get you into "American Woman" territory
Incidentally, your favoured settings are precisely the same as I use on my pedal board.
Try and obtain a 16vAC power pack if you can - and yes that 47 ohm heater dropper resistor will get VERY hot with the additional uneccessary 2v AC supply
cheers
bajaman

I told him that it's a characteristic of the design and not a design fault....

Ever since I finished my build, I've been loving it and enjoying it alot Bajaman, have you ever thought of doing a higher gain version of this?, I do realize that it's hard to get higher gain tube based pedals to sound good...

[ToneKarma]

After two o´clock the pedal becomes really grainy, growly, oversaturated which does not sound so nice to me. Perhaps there is a mistake ... ... any ideas to tame the gain?
It is perfect with the DRIVE set between 10 and 1 o´clock, although you can have nice bluesy tones at low gain settings too.

THERE IS NO MISTAKE
But perhaps you have answered your own question with the last sentence - turn the gain control down
The higher gain settings with tone control adjusted towards the bassier end will get you into "American Woman" territory
Incidentally, your favoured settings are precisely the same as I use on my pedal board.
Try and obtain a 16vAC power pack if you can - and yes that 47 ohm heater dropper resistor will get VERY hot with the additional uneccessary 2v AC supply
cheers
bajaman

I told him that it's a characteristic of the design and not a design fault....

Ever since I finished my build, I've been loving it and enjoying it alot Bajaman, have you ever thought of doing a higher gain version of this?, I do realize that it's hard to get higher gain tube based pedals to sound good...

Thanks a lot lads !

However, I think I will try to tweak the gain of the OP-amp a bit more.

Otherwise it´s a fantastic pedal ! Great job, Steve and thanks for sharing !

Still I have the hope that you will share your Deluxe Drive some day in the future as well ... and if this may only be as a RTS PCB .. nudge, nudge ... wink, wink ...

16VAC power packs are rather rare over here, 15VAC yes but they are quite pricey too.
I shall leave the 47R "toaster" in for the time being and change it if I´ll find a lower output voltage AC transformer

Cheers for now ...

[DrNomis]

After two o´clock the pedal becomes really grainy, growly, oversaturated which does not sound so nice to me. Perhaps there is a mistake ... ... any ideas to tame the gain?
It is perfect with the DRIVE set between 10 and 1 o´clock, although you can have nice bluesy tones at low gain settings too.

THERE IS NO MISTAKE
But perhaps you have answered your own question with the last sentence - turn the gain control down
The higher gain settings with tone control adjusted towards the bassier end will get you into "American Woman" territory
Incidentally, your favoured settings are precisely the same as I use on my pedal board.
Try and obtain a 16vAC power pack if you can - and yes that 47 ohm heater dropper resistor will get VERY hot with the additional uneccessary 2v AC supply
cheers
bajaman

I told him that it's a characteristic of the design and not a design fault....

Ever since I finished my build, I've been loving it and enjoying it alot Bajaman, have you ever thought of doing a higher gain version of this?, I do realize that it's hard to get higher gain tube based pedals to sound good...

Thanks a lot lads !

However, I think I will try to tweak the gain of the OP-amp a bit more.

Otherwise it´s a fantastic pedal ! Great job, Steve and thanks for sharing !

Still I have the hope that you will share your Deluxe Drive some day in the future as well ... and if this may only be as a RTS PCB .. nudge, nudge ... wink, wink ...

16VAC power packs are rather rare over here, 15VAC yes but they are quite pricey too.
I shall leave the 47R "toaster" in for the time being and change it if I´ll find a lower output voltage AC transformer

Cheers for now ...

Both my BRTO plugpacks are 16V AC/ 1.25 A types, and they seem to work fine, I think I paid about $16.00 or so for them, so I agree, they aren't cheap.....


And Bajaman, I am soooooo itching to build one of your Deluxe Drives too, if these Real Tube Overdrives are any indication, the Deluxe Drive should be awesome....

[ToneKarma]

Both my BRTO plugpacks are 16V AC/ 1.25 A types, and they seem to work fine, I think I paid about $16.00 or so for them, so I agree, they aren't cheap.....

I wish they would be $16.00 over here, I would have bought a pair straight away.
The 15VAC/1A I found the other day costs 38.00 AUD / 51.50 NZD ... ... and that´s one of the cheaper ones.

[DrNomis]

Both my BRTO plugpacks are 16V AC/ 1.25 A types, and they seem to work fine, I think I paid about $16.00 or so for them, so I agree, they aren't cheap.....

I wish they would be $16.00 over here, I would have bought a pair straight away.
The 15VAC/1A I found the other day costs 38.00 AUD / 51.50 NZD ... ... and that´s one of the cheaper ones.

Geez, I can understand why you're shocked at the price of one of those.....

Do you get a GST imposed on everything that's bought or sold too?....

Over here in Australia, we do, not sure what the percentage is, though......