Another Prof Tweed thread...

[madboy]

Hey guys and girls.  I hope someone here can help. I finished a prof tweed a while ago, and after having lived with it for a while, and re-listening to the clips, I've started wondering why mine doesn't quite sound the same. Here is a link..

http://www.runoffgroove.com/professor.html

Mine just doesn't seem to have the grit or glassy breakup of the posted samples. I bought a kit for it from OL circuits, and their info posts the same link as above.

The only substitutions I've tried were the recommended ones that came with the kit ( J201's to increase gain. )
The pedal does work, but it seems like more of a cleanish boost than the samples. I can get it to break up a bit more if I really hammer on the strings, but it's not a nice breakup, more of a farty, blatty distortion.
The tone control is also quite subtle, I'm not sure if this is related.

The voltages are set according to instructions ( around 4.6 volts for the drains )

I there anything simple I may have missed? I'm running it of a 9 volt ( 9.3 volts )

Thanks for any info and your time.

madboy

[oldrocker]

I think there is something wrong with your build.  My Professor Tweed has a nice tube grit sound by just turning the knobs full and jammin.  I'm playing through a SS power amp with a DOD G7 as a guitar pre-amp.  The PT breaks up the guitar signal and sounds almost like a tube amp distortion.  If I put a Tube Screamer in front of it, you almost can't tell I'm not playing out of a tube amp.
How are your trim pots set?  You need 4.5v at the trims.  Too low a voltage might cause what you're describing.

[madboy]

Yep, I've set the trims according to the specs ( actually around 4.6 volts ). I'm tempted to rebuild this thing on perf or vero to see if it sounds any different...

[grolschie]

Yep, I've set the trims according to the specs ( actually around 4.6 volts ). I'm tempted to rebuild this thing on perf or vero to see if it sounds any different...

Take clear digital photos of both sides of the populated circuitboard and email them to Mark at OLC. He may spot something weird. He is very keen to help people with their builds.

[markm]

Mines got loads of grit as well......something just ain't right. 

[mcasey1]

At least yours works, .............. :(damnit.

[Threefish]

I haven't built this one myself yet, but it's on my to-do list. I can remember reading this thread that started out about the ROG "18", and went on to the Prof Tweed, regarding the cap in the feedback loop and it's effect on gain. Here it is :
http://www.diystompboxes.com/smfforum/index.php?topic=46070.0

What cap have you got in there? Try this maybe.

[madboy]

I just tried replacing the cap you mentioned in the feedback loop... it seems to have helped! It does darken the sound a little, but does add a bit more grit. The effect seems a bit more pronounced on the low to mid range, but I'll get to try it through a decent amp tonight at rehearsal ( they've rented a dual rectifier for me to play with! ) Thanks again for all the help! Now I just need to figure out which overdrive I need to build to go with it... a tube screamer, a peppermill or...?  Man, this building is addictive.

thanks,
madboy

[Rafa]

Thanks again for all the help! Now I just need to figure out which overdrive I need to build to go with it... a tube screamer, a peppermill or...?  Man, this building is addictive.

JAJAJA
It happend the same to me, now I try to save every cent to build my pedals.
Cheers
Rafa