ShakaTube under construction (built, audio sample available)

[aron]

The rhythm guitars are recorded with the drive pot at its minimum setting, the solo has a little more drive (but it's still pretty close to 0). The tone pot is all the way down for both rhythm and lead.

WOW, your sample makes me want to build one!  

Try increasing the capacitor to ground (connected to the tone stack) by .01 increments (parallel another .01). I think I need to do that as well.

The drive is close to zero??? hmmmm

[aron]

Here's the schematic:

http://www.diystompboxes.com/cgi-bin/webbbs_scripts/webbbs_config.pl?read=309

I want to thank you guys for building my pedals. I really appreciate it and it makes me feel great whenever I hear a fantastic sample like the one posted.

The 100K drive pot, could be drastically lowered to 50K or lower.
(Hindsight).

[transient]

Thanks : )

Schematic:
http://www.diystompboxes.com/pedals/schems/shakatube.gif

I had also found a cleaner (non-hand drawn) schematic, but don't remember where it was, search the forum archives.

Some more info can be found on Paul Marossy's site (http://www.diyguitarist.com).

...
emre

[aron]

Transient's Shaka Tube sounds better than mine! hehehehe

Here's my old sample:

http://diystompboxes.com/pedals/sounds/shakaTubeDemo.mp3

[transient]

Thanks Aron, glad you liked it

I'll try that mod, i actually was thinking of doing something similar to make the tone pot more useful.

What should i do for a little more bass? After some research and reading RG's "Technology of Tube Screamer" article, i found out that the opamp section is similar to a TubeScreamer. So i'm guessing that increasing the value of the 2.2 uf cap will give more bass, right?

Do you think there's a problem with my build, having so much gain?

By the way, i'm building your Booster 2.5 at the moment

...
emre

[aron]

What should i do for a little more bass? After some research and reading RG's "Technology of Tube Screamer" article, i found out that the opamp section is similar to a TubeScreamer. So i'm guessing that increasing the value of the 2.2 uf cap will give more bass, right?

What I've been noticing is that more and more, amps (or settings) might be set brighter than my old Blond Bassman, which I what I used to play through a while back. Therefore, more bass is needed and a less brighter sound.

I guess I would do the following

Increase the .01uF off the last FET drain to .1uF, this will give you a little more bass and might be all you need.

Try increasing the "tone" cap (as discussed before) to filter out more highs.

Put a .001uF cap from the volume wiper to ground to "smooth out" the highs.

Put .001uF caps in parallel with the plate resistors to filter out even more highs (if needed).

Also increase the .01uF input cap in small increments until you get the bass response you want.

One other thing to experiment with is to take off the 22uF electro in the last tube stage. Less gain, but might give more "touch sensitive" feel.

Aron

[transient]

Thanks a lot, i'll try 'em and report back.

.
e

[Paul Marossy]

Mine seems to work pretty well as the "stock circuit". The only thing I did was add a "bright switch" at the ouput, which is just a 0.01uF cap to ground.

[aron]

I fixed the tone pot years ago and promptly lost the notes... well it's somewhere.

I think I replaced the 100K tone pot with 50K, or maybe even 25K and then put a 68K resistor on the wiper. Essentially making the tone only work the lower 1/4 of the original's travel. I believe the 68K goes on the "signal side", then tone pot, then cap to ground.

[Paul Marossy]

Oh yeah, I did use a 50K tone pot instead of a 100K on my last build, too.

[GreenEye]

question:  on the bottom left of the schematic, at the transformer, does it say 10/1W over that resistor with the diodes coming off it?

[markr04]

Yes. It's a 10 ohm, 1-watt resistor.

I'm thinking that value could vary depending on your power supply. 10 ohms doesn't drop enough voltage from my 12VAC supply, so I have 68 there. Maybe someone can elaborate further on this.

[lion]

I build one too - to try as a preamp to add some warmth/saturation to a digital delayeffect - simulation vintage tapeecho. For this purpose it runs (obviously) in the lower gain area, with a just a soft OD. After a lot of experimentation - and missing a little more 'compression', I decide to try a string of diodes in the opamps feedback loop. This works very well - and with adjusting the total Vf of the paralleled diode strings - and 20K trimmers instead of the fixed 10/10K resistors betwen the tube stages - it possible to setup where each stage clips/compresses in relation to each other. For the time being I have a BM-type tonecontrol after the circuit - still working on the details here, for simulation tapeechoes I don't need much bandwith above 3-4 kHz.
One odd thing - I experienced the less than unity bass response as well, and no matter what I did (increasing cap values) I wasn't able to cure it totally () It seems to me that with the trimmer before the first tube stage at higher/max settings the bass increases, turning down causes LF roll off - I'm not smart enough to figure out why.

Erik

[RLBJR65]

I kind of built one of these. Had some problems with my perf layout of the opamp section so I hooked my ROG tube reamer to drive the tube instead, it really sounded awesome Never finished it though, after hearing your clips I'm going to have to get back on it!

I also used 2 bias trim pots one for each half of the tube. As I recall there seemed to be several places you could set the trim pots to get different tones that way.

[george]

What should i do for a little more bass? After some research and reading RG's "Technology of Tube Screamer" article, i found out that the opamp section is similar to a TubeScreamer. So i'm guessing that increasing the value of the 2.2 uf cap will give more bass, right?

What I've been noticing is that more and more, amps (or settings) might be set brighter than my old Blond Bassman, which I what I used to play through a while back. Therefore, more bass is needed and a less brighter sound.

I guess I would do the following

Increase the .01uF off the last FET drain to .1uF, this will give you a little more bass and might be all you need.

Try increasing the "tone" cap (as discussed before) to filter out more highs.

Put a .001uF cap from the volume wiper to ground to "smooth out" the highs.

Put .001uF caps in parallel with the plate resistors to filter out even more highs (if needed).

Also increase the .01uF input cap in small increments until you get the bass response you want.

One other thing to experiment with is to take off the 22uF electro in the last tube stage. Less gain, but might give more "touch sensitive" feel.

Aron

Also try increasing the output cap to about 0.015 or so.

"Increase the .01uF off the last FET drain" ?!?  no FETs in mine Aron ...?

signed A Satisfied Shaka Tube User :-)

[george]

I fixed the tone pot years ago and promptly lost the notes... well it's somewhere.

I think I replaced the 100K tone pot with 50K, or maybe even 25K and then put a 68K resistor on the wiper. Essentially making the tone only work the lower 1/4 of the original's travel. I believe the 68K goes on the "signal side", then tone pot, then cap to ground.

just another $0.02 ...

I have a 10K tone pot because the original was too touchy even with a log taper.  I did have a 100K resistor where you have 68K but it made things too bassy.  I think I now have the same tone control setup as the 9V (3 knob) tube driver .

And the tone cap is 0.047uF.

With this setup I can have the treble up on the amp to have a nice clear clean tone, without getting "icepick-in-the-ears" tone when I kick in the ST

[transient]

Thanks for the tips George.

I've tried a few of Aron's mods, it really helped. I'll report back when i'm done with modding.

Aron meant "tube" when he said "FET". I think calling a tube FET is a side effect of emulation circuits

RLBJR65, i too am planning to try the tube section with other circuits, just out of curiosity.

And Lion, since you're trying to simulate a "vintage" delay, i don't think you need too much bass response. But this is assuming that you've placed the ShakaTube *within* the the delay circuitry (so that it only effects the repeats). Of course, if you have placed it *after* the delay, you'll need bass.

...
emre

[lion]

Arrrgh - sorry for the (more than usual) poor grammar/misspellings in my previous post.

Transient - you are right about the bass response being no problem (for my use - 'inside' the delay), just noticed that it was the case, and found it odd.
Looking into it again, it doesn't make sense - where/how should the bass be 'lost' - I'll have to admit that it points more in the direction of an error on my part.

Erik

[george]

Thanks for the tips George.

np

btw ... nice pics!  nice clip!!! awesome!

[aron]

hehehehe you are right "TUBE"!