BAJA Real Tube Drive pedal project

floris · Post by **floris** » 25 May 2008, 13:15

Thanks Baja, looks nice! Any particular preference for the TL082?
Was there any hum because the heaters are running on AC?

bajaman · Post by **bajaman** » 25 May 2008, 13:51

floris wrote:Thanks Baja, looks nice! Any particular preference for the TL082?
Was there any hum because the heaters are running on AC?

I just happen to like the TL082

No hum if you follow my board layout you will see why - hint: the earth or ground return from the heaters

cheers
bajaman

floris · Post by **floris** » 25 May 2008, 14:59

If I'm correct, I see that the ground return for the heaters goes directly to the other side of the AC power (ground on the schematics). So that's a star-ground, right? Is that why there is no hum due to AC heater power?

So running the heaters on AC never generates some sort of "hum-modulation" in the tube itself? The emitted electron flow from the filament has no 50Hz (in Europe...) modulation? Would that be because the filament acts like a low-pass filter concerning electron emission? (Sorry, but I'm not very savvy with tubes.) So if some tube amp uses AC heater power and hums, it is usually a grounding layout problem?

Gesss, that a lot of questions... you can see I'm in doubt here...

paul525715 · Post by **paul525715** » 25 May 2008, 15:15

Hi,

I have a quick question if that's ok. Would a 16V AC 800mA supply be ok?

Cheers,

Paul

bajaman · Post by **bajaman** » 25 May 2008, 22:09

If I'm correct, I see that the ground return for the heaters goes directly to the other side of the AC power (ground on the schematics). So that's a star-ground, right? Is that why there is no hum due to AC heater power?

You got it first time - yes it is all about grounding practice. A well designed and laid out tube amplifier will not hum.
I have used dc heater supplies in the past, but having learned the correct way to supply the heaters wiring wise, I always use ac heating nowadays - with NO hum problems.
The Matchless people took it one step further with their DC30 amplifier in particular - they ran separate twisted AC heater supplies to each tube gauranteeing no intermodulation effects between each amplification stage.

So if some tube amp uses AC heater power and hums, it is usually a grounding layout problem?

Not always - it could be a bad input reference earthing problem or bad filter capacitors etc.

Would a 16V AC 800mA supply be ok?

Yes - should be okay, but may run a little warmer - try it and see - let us all know if their are any heat problems

Cheers
bajaman

Dror · Post by **Dror** » 09 Jun 2008, 22:31

Hi All,

Here is a stripboard layout for this project.
https://i137.photobucket.com/albums/q23 ... Layout.gif

It's not a confirmed layout since I didn't built it yet.

Enjoy and let me know if there are fixes.
Dror

jrc4558 · Post by **jrc4558** » 10 Jun 2008, 15:45

Oh my god, I would love to build this thing! One thing that is holding me back is my ability to drill the enclosure precisely to filt the board-mounted jacks, switches, and pots. Any tips/hints here?
Thanks!!!

minor7th · Post by **minor7th** » 10 Jun 2008, 21:10

jrc4558 wrote:Oh my god, I would love to build this thing! One thing that is holding me back is my ability to drill the enclosure precisely to filt the board-mounted jacks, switches, and pots. Any tips/hints here?
Thanks!!!

You could use the enclosure drilling template that Bajaman put in his package...

Dror · Post by **Dror** » 11 Jun 2008, 21:44

Dror wrote:Hi All,

Here is a stripboard layout for this project.
https://i137.photobucket.com/albums/q23 ... Layout.gif

It's not a confirmed layout since I didn't built it yet.

Enjoy and let me know if there are fixes.
Dror

I did forgot 1 resistor so the above link is updated.
It's still not aconfirmed layout, so do it on your own risk.
Please note that If the old gif is cached you won't see the update. press the link and after refresh the cache by Shift+F5.

Cheers
Dror

sadrew · Post by **sadrew** » 18 Jun 2008, 12:35

Hi bajaman,
i have a 12ax7 doing nothing so i want to build a tube od.
what are the differences between your beast and the butler tube driver?
i have to make a choice but it's so hard without any sample.
thanks

bajaman · Post by **bajaman** » 18 Jun 2008, 12:50

mine sounds better

bajaman

sadrew · Post by **sadrew** » 19 Jun 2008, 22:52

i will trust you and give it a try

stephenxvp · Post by **stephenxvp** » 07 Jul 2008, 12:31

Finally getting round to building this beauty. Drawn out my own stripboard
Just one small question though; I have a 17 volt supply, +ve and -ve (is that called bipolar?)
Can I use that to power the op-amp and the tube/valve or does it need a little reducing?
Thanks for the cool projects and the fascinating reading,
Stephen

minor7th · Post by **minor7th** » 07 Jul 2008, 12:39

stephenxvp wrote: Just one small question though; I have a 17 volt supply, +ve and -ve (is that called bipolar?)
Can I use that to power the op-amp and the tube/valve or does it need a little reducing?

Is it AC or DC? This pedal takes AC.

stephenxvp · Post by **stephenxvp** » 07 Jul 2008, 20:28

No, I would usethe 17volt supply instead of the rectified AC voltage, with a 5 volt supply for the heaters. It woumake the board a bit smaller and use a power supply I have just lying around.

Gibson78 · Post by **Gibson78** » 06 Aug 2008, 16:00

Hi, how high can I run the pedal? 18VAC? Looks really good!

Cheers and Beers!

bajaman · Post by **bajaman** » 06 Aug 2008, 21:51

As long as you use 35v rated electrolytics for the input main filter capacitors - should work okay.

bajaman

Gibson78 · Post by **Gibson78** » 07 Aug 2008, 09:48

Thanks for the quick reply Bajaman! I'm also building your other tube pedal - just to compare both of them. Will let you know as soon as I finish them both.

Cheers and Beers!

hunter · Post by **hunter** » 20 Aug 2008, 19:49

Hi Bajaman
I am also in Christchurch and am a bit of a hobbiest pedal builder.
I have had some success but my undoing has always been the PCB etching.
I would love to have a go at building one of your Real tube overdrives.

So I was wondering if you are selling any pre etched boards for them?
Please let me know.

Cheers
Mark

(I also have an old Holden 50 head that I would love you to have a look at for me if you still do amp work)

schumann · Post by **schumann** » 29 Aug 2008, 14:40

Hey bajaman!

I'm from Singapore. I'm pretty new towards tubes. May i know if a "holder" was used at the tube?
Forgive for my noob question, I'm really interested to build one my own.

Schumann

BAJA Real Tube Drive pedal project [documentation]