GCB-95 Bass response

[Marra]

Hi,

Recently I modded my GCB-95 to Paul Marrossy's tastes and i love the new sweep and vocal quality etc. I was also hoping it would fix the poor bass response, but if anything its made it worse. Its so muted in the heel position that it sounds more like a wah/volume hybrid. Can anyone suggest what I might do to fix this?

Any help would be very much appreciated as i LOVE the tone of the thing, but at the moment its unusable.

Thanks!

[nero1985]

i had a problem like this before, there are two ways to fix it, eighter move the pot so that its a little bright when its toe up or put a piece of rubber in the back of the rocker, this way you wont have to go all the way down to the LOW frequency, i did this and it works better now

[Paul Marossy]

I would say that adjustment of the pot is in order.

[KRK]

I would say that adjustment of the pot is in order.

Is that as simple as changing the position of the gear turning the pot? I haven't opened mine up and honestly naver gave much thought as to how much play there would be.

[Paul Marossy]

Yep. The wah doesn't use the whole rotation of the pot. There's usually some room to go up or down. 

[KRK]

Yep. The wah doesn't use the whole rotation of the pot. There's usually some room to go up or down. 

Thanks! I may have to play with mine a bit.... Wah that is 

[Paul Marossy]

Please let us know if you get it to your liking! 

[KRK]

Please let us know if you get it to your liking! 

Unfortunately the play is all in the wrong direction. No worries though I'm still happy with it.

Thanks for the advice!

[Paul Marossy]

Hmm... I think that the value of the inductor must have something to do with these wah pedal mods. I did the Fat Wah mod to a friend's GCB-95 wah pedal, and it sounds quite a bit different than my Fat Wah mod does. 

[formerMember1]

could be the pot itself too.  The fulltone pot had a dead spot, the propot didn't for me.  I think the dunlop pots have adead spot too.

Did you do the obvious and play with the bass resistor?  I assume you did.  I also read on castledines site(or another site?) that raising  the 1k5 mids resistor will help if your pedal sounds dull and muted when rocked back.  I like the mids at 1k5 though, it is too touchy to change it for me.  Even 1k8was too high. I acutally like to just use the 5%tolerance of resistors as a "mod".  Some wah mods people do are way to extreme.

To adjust pot loosen white wire clip, push gear back, rotate pot to full treble with pedal squeezed and switch depressed, push gear, tighten clip, try out, then try backing off one tooth at a time.  I like doing what 1wahfreak said, and manually turn the pot to treble and rotate back until you get to a tooth rigth before the treble changes, for maximum quack and sweep.

I like to remove all rubber stopppers and felt pad, i could never get a dull spot if i tried.

funny thing, Actaully i was trying a few weeks ago to make it dull an muted at heel,  Jimi had it that way at the bcc sessions album.

I have to look into that fatwah mod paul marrossy has on his site, i would like to try that.  I was reading a while back and i thought it was just an input buffer installed, but i guess it isn't since you talked about doing this to your dunlop wah and it has an input buffer already,..

[GBlekas]

My guess would be the .01 cap that goes to the emitter of Q2 was raise to a .018 uf or higher. This would be better for a bass than a guitar but it is an obvious change to the circuit tone wise.

Changing the 4.7 uf to a higher value would also make the pedal woofy as well. The best I ever hear read 3.9 uf and unfortunately not a value that is available today unless you are lucky enough to have found a stash of them somewhere. Lowering to a 3,3 uf will brighten up the circuit as well.

The resistor off Q1 to ground can also be lowered too much to create an overly saturated tone as well. I found the standard 510 ohm to be too high and like to play with this one. a small trim pot would be cool in this part of the circuit.

For great tone keep your transistors in the 300 or less HFE range.

Hope this helps.

Regards,
George

www.PedalworX.com

[Paul Marossy]

I think I am going to try that with my 70s Vox Fasel wah (raising the value of the 0.01uF cap at the emitter of Q2). It's just a little too shrill for my liking right now... 

[GBlekas]

The absolute best way to deal with a wah is to find one that you think sounds killer.
You might need to spend a few dollars in the process but when you find the holy grail of a wah you need to lift one leg of every part in the pedal and take a measurement.
Take notes because you will probably only need to do this once or twice, should you find two that catches your fancy for different reasons.

There isn't many parts in there so it's definitely not rocket science and should be quite easy.
There are some other tricks one can do to a wah that are not posted anywhere and I ain't saying

The best inductors are the Stack of Dimes and Halo.
I have seen many TDK and Fasel inductors and something like 9.5 out of 10 the TDK isn't good and the Fasel has been somewhat better than the TDK with perhaps 5 out of 10 needing to be replace to get "the tone". 
Fasel as the holy grail inductor is a myth, imho.

Regards,
George

www.PedalworX.com

[Marra]

Ta for the responses!

I had already moved the pot into optimum position, so I think its something else on my particular wah. Everything is socketed, so im going to try as many different values as I can. Ill let you know if something works particularly well. Id rather not go with removing rubber stoppers etc becuase, well, thats just cheating!

Now that I think about it, im pretty sure it was muted even before the mods but I just never used it enough to notice. Does this mean I should start looking at transistors, pots and inductors? Ive been looking for an excuse to do that for a while....

[Paul Marossy]

Id rather not go with removing rubber stoppers etc becuase, well, thats just cheating!

Well, not really. It's necessary if you want the maximum sweep possible from your wah pedal. Remember, the pot does not go thru its full rotation in the CryBaby wah... 

[GBlekas]

Id rather not go with removing rubber stoppers etc becuase, well, thats just cheating!

Well, not really. It's necessary if you want the maximum sweep possible from your wah pedal. Remember, the pot does not go thru its full rotation in the CryBaby wah... 

+1
Don't remove the rubber, just trim it down.


Transistors aren't your problem. It's most likely either the 4.7uf to ground or the .01 to the emitter of Q2 are to high of a value.
I am pretty sure the value has been a .01 and 4 uf for a good reason.

Regards,
George

www.PedalworX.com

[Marra]

Hey,

I trimmed the rubber down at the front and added a little rubber foot at the back. Definately an improvement.

However, its still not quite "it". It's something to do with the feel of the thing. Its a bit limp and doesnt 'choke' enough for my liking. And the bass is still a tad weak.

So ive come up with 3 possible ways to sort this out once and for all:

1) Buy a new inductor/ pro-pot off Stuart Castledine and fit them to my GCB-95.
2)Buy a new inductor/ pro-pot off Mr Casteldine, and make a fresh start with my own Clyde McCoy circuit.
3)Get a cheap Vox V847 off ebay and mod it (ive heard good things.....)

Which do people feel would give the best results? Or maybe theres another option that ive missed? I may very well end up tinkering with the GCB-95 for a while without any of the above, but id be interested to see what people think.

Cheers!

[Paul Marossy]

Changing the inductor might help with that. The inductor does play a role in the overall frequency response and quality of the circuit. If you could measure your current inductor's DC resistance and inductance, we could determine the best course of action to take.

Building a Clyde McCoy clone will probably get you a really good sounding wah, if you do it with "the right parts".

You could buy a wah off of ebay, but your results may not be any better than what you currently have. 

[Marra]

Thanks for the advice Paul.

How do I go about measuring inductance? I Googled it, but all the methods involved kit that I dont own 

formerMember1, I remember reading a thread you started a while ago when you were building a Clyde McCoy. Any useful tips about components etc? I think im essentially after the same sound you were.

Thanks - Marra

[GBlekas]

Before you go nuts buying replacement parts try a 1k trim pot off Q1 to ground. This would replace the standard 510 ohm resistor. As this gets below 510 ohm you will notice a fatter bottom end. Too low of a value and the pedal will saturate to you have to tune it by ear. You could even find your sweet spot and remove the trim pot in favor of an equal valued fixed resistor.

Besides this you could raise the input cap to let in more bottom end into the circuit.

Also, remove the inductor and measure the resistance on it. It should read about 4o ohms. If it reads under 20 ohms this is not a good inductor. The only way that I have found to get those to work is to put two of them in series. Then you could have some serious mojo happening.  You might have to tweak a few other values in circuit to keep the bottom from getting to be too much though.

I have tested many pots in the wah and found, for the most part, all to be more or less the same. The blue Bournes pot was the only one I did not like.
100k or 200k makes no difference in a wah, imho.
Small Bear has good prices on parts and I have NOS Stack of Dimes and Hot PotZ II, if interested.
I have not tried the Pro-Pot but heard from formerMember1 that it's a good one.

Keep us posted and have fun!

Regards,
George

www.PedalworX.com