BAJA Real Tube Drive pedal project  [verified]

Original effect designs complete with verified schematics, layouts and instructions. All project were freely contributed by members and cannot be used for commercial purposes without consent of the respective owners of the copyright.
stojanos
Posts: 27
Joined: 06 Oct 2016, 17:56
my favorite amplifier: fender 57 deluxe
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Baja Real Tue Driver, Really Cheap Compressor

Location: London
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Post by stojanos »

schemripper wrote:
bajaman wrote:Hi schemripper
You could try decreasing the 2 x 47k plate load resistors - try 22k for example when using the lower plate impedance 12 AU7 type tubes - A 12AT7 might work okay in here too. :wink:
Cheers
bajaman
Hey, Bajaman, I've said it before but what a great circuit. The 12AT7 did work, but was still a bit too much.

I found a very old 12u7 (12v ex car radio valve- just like Brian May! ;) ) in a dusty box in the very back of the workshop. I swapped in some 78/7912s to get the voltage down, and ended up with 18k for the plate load resistors- that's probably the dubious state of the valve more than anything. I think it's probably that the 12u7 is operating at its intended voltage, but it has that little bit extra sweetness over a 12au7 to my ears.

It also opens up the possibilities of running it at a regulated 12v dc, but that's too much hard work when I already have a working device :) Any other little fiddles I tried didn't provide sufficient returns for the effort. The tone stack (what there is of it... ;) Simple and effective) was pretty much spot on.

Overall- it suits my needs, but if anyone else tries this, YMMV. Remember- a 12(a)u7 is not a gain monster. It's about 20 vs 100 for a 12ax7.
Hi Baja and Schemripper,

I also want to play with tubes. What do you think will make a bigger difference: different 12AX7 manufacturer or different tube type (ECC83, ECC82, ECC81). My logic is to first find the best tube type for sound that I am looking for (buying cheap chinese tubes ) and than to tweak it further if necessary with more expensive one of the same type. Also is playing with plate resistors affecting too much sound or this is only to get optimal voltage for longer tube life.

Thanks,
Srdjan

stojanos
Posts: 27
Joined: 06 Oct 2016, 17:56
my favorite amplifier: fender 57 deluxe
Completed builds

Baja Real Tue Driver, Really Cheap Compressor

Location: London
Has thanked: 7 times
Been thanked: 9 times

Post by stojanos »

Just to report back that pedal worked and that I have settled with 12AU7. 12AX7 sounded more like a BRIT amp overdrive and it did not work well for with my strat -> 69CS -> 5E3 setup. It is off course very subjective. Thanks Steve !!!

bopelado
Posts: 2
Joined: 10 Apr 2015, 14:07

Post by bopelado »

I was wondering if the opamp gain si based on other pedal? I know gain pot on feedback is used by tubescreamers but the whole gain until tube is based on other? I'm thinking in bulilding only that part tu use with only tube pedals like matchless and valvecasters.

rafammbass
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Joined: 31 Aug 2010, 02:39
Location: Ottawa, ON
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Post by rafammbass »

Just wondering if PCBs are still available for this project?

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bajaman
Old Solderhand
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New Brighton, Christchurch, NZ

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Post by bajaman »

rafammbass wrote:Just wondering if PCBs are still available for this project?
yes :D
pm me for details
cheers
bajaman
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nonost
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Joined: 27 Mar 2017, 01:27
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Post by nonost »

Great project!

Any problems if using true bypass?

What does it mean the 100nf - 100r in the schematic? Is it to ground the enclosure?

Thanks!

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bajaman
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Post by bajaman »

yes
be kind to all animals - especially human beings

sidmanp
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Joined: 01 Jul 2020, 10:25
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Post by sidmanp »

IMG_20200701_120737.jpg
Haha I have one of these... Bought it second hand in Akl.
Great sounding thing.
A bit hard to use nowadays though, as I have a pedal board powered by a onespot cs12, which doesn't do 16v AC.


Cool to read up the backstory on here though, I had no idea about its history. I was directed here from Reddit.
Thanks bajaman

nonost
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Post by nonost »

I'm wondering if a 18v ac supply would be better...With 16v ac after the 4007 it drops to 15.5v and I though regulators worked better with a 1v or 2v margin. But I might be wrong, I'm not an expert at all. I'm sure there's an explanation to that.

Cheers!

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