Dunlop - Cry Baby GCB-95: how to improve it for cheap

FloydFan · Post by **FloydFan** » 06 Sep 2008, 19:02

Thanks for having moved my 3d

However , today I've been searching into my father's old diy circuits (made in the 70's) and i've found several tropical fish, Ducati, ITT and others caps and bags of carbon comp resistors as well a pair of BC109 ... I feel like I won the lottery

Unfortunately I have to change the pot..what do you suggest ? Fulltone copy,Pro Pot Deluxe,black top audio or a simple and cheap life pot (like the roger mayer ones)

Solidhex · Post by **Solidhex** » 06 Sep 2008, 19:09

yo

I like the Black Bear pot from Small bear. Got a scratchy one once but they sound good and aren't too expensive.

--Brad

FloydFan · Post by **FloydFan** » 06 Sep 2008, 19:15

Thx but I have to order it at Banzaieffects !

I'm a bit unsecure about that black anti-dust cup which the pro pot has ..and it costs the same as the fulltone copy (16-17€)
What should I do ?

Post by **modman** » 17 Sep 2008, 18:57

FloydFan wrote:Thx but I have to order it at Banzaieffects !
I'm a bit unsecure about that black anti-dust cup which the pro pot has ..and it costs the same as the fulltone copy (16-17€)
What should I do ?

Buy the ICAR Black Bear. It's really high quality stuff with a 'long dead zone' and a steep reverse log taper that makes your wah wah really ohlala! Don't know the Fulltone pot, never heard reports on that.

boxnix · Post by **boxnix** » 26 Sep 2008, 01:55

After hours of goofing with my GCB-95 wah I now have a slightly less crappy wah lol. Whipple is still comming though.

On to the question.

I added a 100K pot in series with the 33K resistor that determins the "Q" or if your wah is a wah or a woh... supposidly. After adding the pot I hear zero change in the sound of the wah. 133K ohms is above any recommended value and I sort of expected some unusable sounds. I am hearing no change from 33K to 133K. Is this a REALLY subtle effect or did I screw something up? It sounds fine, I was just expecting a lot more.

Thanks!

jrc4558 · Post by **jrc4558** » 26 Sep 2008, 13:29

OMG, and I thought that I'm alone!
That's the only mod I never heard any useful function from. True story, imho.

bajaman · Post by **bajaman** » 26 Sep 2008, 19:47

You will hear a difference with th Whipple inductor.

bajaman

Fuzzer · Post by **Fuzzer** » 27 Sep 2008, 14:59

Something I found useful when pimpin' my wah was to build a small board with a DIP switch which adds capacitors in parallel, in place of the .01 sweep cap.

I arranged 9 caps as in the Real McCoy Wahs, the values are the following;

220 [pF]
470 [pF]
820 [pF]
1.5 [nF]
2.2 [nF]
4.7 [nF]
10 [nF]
22 [nF]
47 [nF]

Enjoy.

Oh, a question for bajaman, or anyone who has tried changing the 4.7 [uF] capacitor for 4 [uF]; is the audible difference somewhat only in conjuction when you use the upgraded whipple inductor? Because to me these parts are unavailable, so I just have the stock dunlop coil and pot and I found that using a 6.8 uF was the beneficial thing.

Thanks in advance.

boxnix · Post by **boxnix** » 27 Sep 2008, 16:55

I pulled the trigger on the tropical fish caps, xicon caps, new switch and ICAR pot. I'm gonna try the 4uf cap thing too. Whipple is still on the way.

Bside2234 · Post by **Bside2234** » 27 Sep 2008, 17:00

I have a couple of axial 4uf caps that I am going to try to fit in one of these days to see what it does.
What did the 6.8uf cap do?
I should take a picture of my Crybaby. It's got 4 switches and 3 inductors! One switch adds bass, the other 3 switches switch a red fasel, a yellow fasel, and a Whipple on and off. So you can have any one inductor or any combination of the 3.

Fuzzer · Post by **Fuzzer** » 27 Sep 2008, 18:11

In the GEOFEX article about wahs it is stressed that over 4.7 [uF] there will be not much difference, but under 4 [uF] the wah will start to behave more as a volume pedal than a wah. The thing is, I found it to be a more solid 'wah' using the 6.8, maybe it din'd even had to do with the value, my pedal is a little old, so maybe the 4.7 was going defective and thus I heard a difference.

Bside2234 · Post by **Bside2234** » 27 Sep 2008, 19:10

The Maestro wahs used a 6uf cap here. I'm sure I have seen others.

Fuzzer · Post by **Fuzzer** » 27 Sep 2008, 19:45

Thanks for the tip, but also, according to fuzzcentral, some old Clyde McCoys used a non-polar 4 [uF], Ducati brand. I'll have to wait to try the change, because I have the 3.3 NP but ran out of .68 [uF]. If you try it fist let me know, please, I'd appreciate it greatly.

ChristoMephisto · Post by **ChristoMephisto** » 28 Sep 2008, 18:33

I did a complete overhaul on my GCB95 wah to Maestro specs (now that's a wow pedal)
http://www.diyguitarist.com/DIYStompboxes/Boomerang.htm
Originally left the 4.7uf cap as is, and found the wah 'tight'
Replaced it with a 10uf (didn't have a 6uf on hand, or bother with 4.7//2.2 caps) and found that it opened it up
On the other hand, my Vox Thomas Organ Fuzz/Wah has a 3.9 uf tant cap and the wah is perfect

Has the Q mod with a pot, the lower the resistance, the sharper the peak, altho can be subtle. Try yours after a comp/dirt pedal and you should notice it there.
The Technology of Wahs is a good artical to read, I agree

Fuzzer · Post by **Fuzzer** » 28 Sep 2008, 19:23

Thanks for the tip, I was thinking today that maybe I'm paying too much attention to this issue and probably the 4 [uF] is recommended because it attenuates some lows and thus keeps the wah from muddying, I might be wrong, but is the first thing that occurs to me as a solid reason to pick that value.

Post by **modman** » 28 Sep 2008, 20:36

Fuzzer wrote:Thanks for the tip, but also, according to fuzzcentral, some old Clyde McCoys used a non-polar 4 [uF], Ducati brand. I'll have to wait to try the change, because I have the 3.3 NP but ran out of .68 [uF]. If you try it fist let me know, please, I'd appreciate it greatly.

You can make a 4uF non polarized by putting two 2.2uF caps in parallel too. If you connect each + to the - in the other cap, you have a non polarized. If you have some cheap electrolytics in stock, you will see you will get 4.05uF or so. I'm really stupid except that I bought a DMM with capacitance meter and I know now the below is bullshit.

[quote="from diystompbox wiki]From Jack Orman:You can simulate a non-polarized by using 2 electrolytic caps. Connect them together negative to negative and use the positive leads as the component leads; which is probably why someone notated it as +-||--||-+

From R.G.

"You can make a quick and dirty NP cap by tying together the negatives of two equal-sized polar caps.

In the series-NP connection, the capacitance value is funny. Normally caps in series are a smaller capacitance than either cap by itself. If you had two 3.3uF polyester caps, then the expected value for two of them in series is 1.65uF. However, electrolytic caps actually conduct in the reverse direction, so two 3.3uF polarized aluminum electrolytic caps act like they each have a diode in parallel with them that conducts when the voltage is backwards for that one cap. So two 3.3uF caps hooked up as series non polar (i.e. negative to negative) look like a single 3.3uF NP cap.
... except for tiny region near zero volts where they withstand a tiny reverse voltage, so they look like 1.65uF there..." [/code]

I even had to read this 3 times, but: I know capacitance in parallel adds up
when I connect the +'s together and measure two 1uF electrolytics in parallel = 2uF
when I connect the + to the - and measure two 1uF electrolytics in parallel = 2uF
when I connect the +'s together and measure two 1uF electrolytics in series = 550nF
when I connect the -'s together and measure two 1uF electrolytics in parallel = 550nF
when I connect the + and the - together and measure two 1uF electrolytics in parallel = 550nF

There are a lot of problems regarding the Technology of the Wah article as the definite words about wahs.

Cout -- still working this one --
Cef-- still working this one --

Also, these 10nF capacitors were not tropical fish Mullards, but polystyrene as we know from Fuzzcentral documentation. The Mullards are 20% tolerance, so falling for these vintage suckers may degrade your sound to below Behringer wah level... As Bajaman noted earlier, these are the caps that have to make your pedal wah through an entire octave, and as the rule of thumb that is more to go by than the entire Technology article

"Let me know how that change sounds..."
The big unknown in the equation is the impedance of the wah coil. I agree as stated above, that a 100k pot in parallel with the coil (instead of the 33k or 100k) does not affect a stock Crybaby circuit. I always kick out the buffer (first thing) of Crybabies, makes them sound hard and boosted, while a real nice wah should be sweet and I'd almost say 'thin'.

m

floris · Post by **floris** » 28 Sep 2008, 20:47

ChristoMephisto wrote: http://www.diyguitarist.com/DIYStompboxes/Boomerang.htm

I get a: "404 Not Found error"

Post by **modman** » 29 Sep 2008, 09:52

floris wrote:
ChristoMephisto wrote: http://www.diyguitarist.com/DIYStompboxes/Boomerang.htm
I get a: "404 Not Found error"

I don't and I hadn't looked at that page in a long time

Some good info there which supports my case of "wah loves low gain transistors"

I honestly don't know how mine sounds compared to the real thing, but it sure sounds good with the reissue yellow Fasel inductor. After playing this for a while, it appears that the 2N5089 transistors may have slightly too much gain for clean wah sounds, but it does sound great with distortion! I tried out some MPSA18s in it to see if that would get a little better clean sound,

Update 11/20/05: For clean wah sounds, the MPSA18 transistors still had too much gain as some distortion would occur, especially with a humbucking pickup. I can find no data on the transistors originally used in the Boomerang, but I am guessing that they are general purpose transistors with an Hfe of around 200-250. I had some 2N3569s lying around that were within that range, and those work better still.

Update 12/26/05: I still wasn't completely satisfied with the 2N3569 transistors, so I decided to try some BC109s with an Hfe of around 400, and now I am finally totally happy with it. It actually sounds a little more vocal with these transistors, to my surprise.

Hfe400 is really high for a BC109, and in the US without BCs around, I would try 2N2222 metal cans.

bajaman · Post by **bajaman** » 29 Sep 2008, 11:38

I must try some MPSA42 devices - very low gain (100 - 200)

cheers
bajaman

Fuzzer · Post by **Fuzzer** » 29 Sep 2008, 14:34

Heeey mister Bajaman, what's the deal with the 4 [uF]?

Thanks