"Shaka Tube" re-visited and mp3 .... HELP !

[MartyMart]

http://aronnelson.com/userfiles/Shaka%20full:min%20gain.mp3

OK, I dont want this to have to turn into a 7 pager, like last time
Trying to get this right now, here's what I have :
New 12v AC supply @ 1200 Ma
Circuit back as "stock" with just a couple of extra caps at the power board
V+ V- and bias, to ground ( 470n poly's )
Tried re-wire for a TLO72 and sounds exactly the same ....
Now have an NE5534AP in.
The sound sample :
First chords with "gain" full ... how does this sound to you ? a little miss-biased ?
Not bad though, tone and volume working well, but at full gain it's a bit quieter than ...
Second chords with "gain" at min ... brighter and much louder, still some distortion.
If I can solve this "wierdness" then I'm happy
Gain pot is wired thus :
Lug 1 from op amp pin 6
Lug 3&2 from op amp pin 2 with 220 ohm /2u2 to ground and 220pf cap across pins 6/2

Thanks,
MM

[8mileshigh]

Marty,

It sounds a bit splattery to my ears, it's one twaek or two from being "there".  How's that for technical advice 

Chris

[RLBJR65]

Marty, I still think you need to try two bias trimmers 1 for each half of the tube.

Richard

[MartyMart]

Update :
So I've rewired the power section ( neater ) put the TLO71 back in.
swopped the valve from a Marshall ECC83 to an older and much better Mullard
12AX7 - type.
Re-wired the "gain" section, as it looked a bit "odd" to me .

Result :
Gain ranges from "slight" overdrive to "medium" but without the level drop 
The tone and "richness" of the OD is WAY WAY better, no "splatty" sounds now.
There must be a way to get more signal from the op amp, because when driven
by a compressor/booster the OD increases and sounds better to me ... ?
How about a 250k gain pot , anyone tried this ? or will I start to get more
op-amp clip that way ?

Well, 85% there ....

MM.

[Paul Marossy]

Increasing the gain pot to 250K would be worth a try. That would increase the gain in the opamp quite a bit compared to the 100K pot. This reminds me of the first time I built the Shaka Tube - I wanted to smash the thing because it just refused to work right!  Anyhow, keep at it, I think you're real close on this one. 

[PurpleTheory]

i built one recently and had the same gatey, farty problems. since i perfed it i thought i must had made some error in the process, so i rebuilt it only to end up with the same problem. i read some old threads and found something that fixed the problem. i built the tlo72 version, so hopefully this is even relevent.



i just added a 10k resistor between the two green dots and took care of the problem completely, now i have 2 shaka tube pedals. don't know if that helps, but worth a try.

matt

[A.S.P.]

Just for reference...

[MartyMart]

i built one recently and had the same gatey, farty problems. since i perfed it i thought i must had made some error in the process, so i rebuilt it only to end up with the same problem. i read some old threads and found something that fixed the problem. i built the tlo72 version, so hopefully this is even relevent.



i just added a 10k resistor between the two green dots and took care of the problem completely, now i have 2 shaka tube pedals. don't know if that helps, but worth a try.

matt

OK, so you take opamp output ( pin 1 ) to 10k, then the 250pf before drive pot .... yes ?
You would have "cut" that trace then ...to insert the 10k
Thanks,
MM.

[Paul Marossy]

You would have "cut" that trace then ...to insert the 10k

Why would you have to do that? I think all you have to do is add the resistor between those two points, or at least that is what I interpret. I'm still perplexed as to why y'all are have a problem with gas... 

[MartyMart]

You would have "cut" that trace then ...to insert the 10k

Why would you have to do that? I think all you have to do is add the resistor between those two points, or at least that is what I interpret. I'm still perplexed as to why y'all are have a problem with gas... 

I dont have that kind of "gatey/farty" problem at all, I just seem to have almost one "drive"
level ... ? ... which a 250k pot made even more "equal" if you like !
It's either "slightly clean" or "slightly dirty" and I'm beginning to wonder if the tube
is being driven at all !
Could it be that a booster up front is just overdriving the op amp ?

MM.

[MartyMart]

I think that I've found my problem..... you're going to LOVE this .

...... my 12AX7 pin connections are totally REVERSED  !!!!   

That shows you my "Tube" knowledge  eh !!

Rewire time ..... Sorry guy's ....

MM.

[Paul Marossy]

I think that I've found my problem..... you're going to LOVE this .

...... my 12AX7 pin connections are totally REVERSED  !!!!

Doh! Those tube pinouts will get you every time. 

[MartyMart]

Oh man, how could I have done that !    what a "dumb ass" ....
I checked the pinout, then built it and by the time I wired up all the
tube connections, I must have just "reversed" the image in my mind ...
looking at my ceramic tube socket upside down .... DUH  !!
I just hope I have not "ruined it"  I had pin 1 as pin 9  !

Oh well, lesson learned for sure . !

MM.

[Paul Marossy]

Well, worst case is that you need a new tube and opamp. It's easy to get those tube sockets messed up. All you have to remember is that you're looking at the bottom of the tube with respect to the pin numbering.