Fixing that Ibanez WH10 tone suck

[rockhorst]

The Ibanez WH10 (V2) is notorious for sucking tone in bypass. People have discussed this, but no one (as far as I can see) has actually come up with a solution. Hacking a 3PDT into the enclosure is one way of course, but this seems silly to me. I've noticed that there's no tone suck with a buffered pedal in front of the wah, so it's supposedly and impedance issue. I could add a buffer to the enclosure, which is, IMHO already better than the 3PDT. But the best thing to me would be to fix the unit's own input buffer. I just don't really understand where it goes wrong. It seems pretty run of the mill. A schematic was drawn up a few years ago by Dirk Hendrik and can be found here.

Referring to this schematic, so far I've increased R2 to a 1M resistor and removed C20 and C21 (although their corner frequency is well above 20kHz). This makes a mild improvement but not a lot. My next guess would be to remove/lower R1 and R31 (maybe to 100R total). However, I've seen effects with input jfet buffers with a 1k series resistance that seem to not suck tone. I can't work on the unit right now, hence I thought I'd post it up here for ideas. Has anyone identified (and fixed) the culprit? As said, with something like a Klon buffer in front of it, bypass doesn't suck any tone.

[PRR]

2n2 caps in and out seem VERY high. That's 2,200pFd, which is like 73 FEET (22m) of cable. That sucks guitar. Less on buffers, though still loading the top of the guitar band.

Someone must have been playing under a big radio transmitter.

Try few-hundred pFd.

> removed C20 and C21 (although their corner frequency is well above 20kHz)

No. Their "R" is not 220r but "the guitar": 5K + 5H (and the 220r). They are real suckers.

Use much smaller caps. Add some resistance so WABC-AM or taxi-radio does not play duets with you.

C1 shaves lowest guitar notes. Your 1Meg is better.

[rockhorst]

Thanks for the reply Paul, and sorry it took a while for me to get back to it. What is not entirely clear to me is what the 10k at the input does. Won't that just load the signal even more?

[rockhorst]

I tried the modifications Paul suggested: works like a charm. With the pedal in the signal chain there is now slightly more top end, indicating that the pedal's input buffer is doing it's proper thing now.

[Jordansooks]

Hey rockhorst,

What were the exact modifications that you ended up doing? I'd love to do this myself and write up a guide for others who are interested in fixing this problem (as well as showing how to add a volume pot to the pedal)

[rockhorst]

I'm not a 100% sure what I ended up with...try these things and see if it works. If not send me a note and we'll figure it out

The following is not what I did but thinking about the schematic now I think it should work:

Jumper R1, R31 and C1, double or triple the value of R2 and lower C21 to 50 pF. Remove C19 and C20.
If you get some radio interference, use a 470 to 1k resistor in place of R31 or R1.

[anotherjim]

I'm not sure the input is entirely at fault.
For sure, the RF filter cap C21 could be smaller than 2n2 and R2 can be raised to 1M or more.

...but 3 stages of "unity" buffers and a FET switch are probably adding a little loss & distortion of their own - not so much tone-suck as tone-change. A change to mechanical switched true bypass is probably the best cure. If you don't want to mod it heavily, simply use with a send/return loop pedal.

...maybe the K30 JFET's in any particular example are not best biased via a half supply 10k/10k divider. A 20k, 22k or 25k multiturn trimmer in place of R25 & R26 might find a sweet spot bias voltage that suits them better. It don't matter in bypass, but the LM358 op-amp gets better equal headroom with a lower bias voltage than half supply - closer to 3.5v than 4.5v.

[rockhorst]

@anotherjim: I have had some first hand experience modding the pedal. I should've kept my notes on it to be sure what I did, but there is an easy fix. It is def. the input buffer. I tinkered with the output side of the pedal and that didn't do much. It is fixable and the mod is easy to do. It'll be a much better pedal. Instead of TB-ing it, a much quicker fix would be to stick a better buffer in front. It's not a great pedal to try and stick a TB switch in. It requires drilling a new hole or some other 'redecorating' if I recall correctly.

[xaxxop]

Hello guys, sorry for bringing this old post up but I wondering if anyone found a solution/mod/fix for this issue?
Thanks

[rockhorst]

I think the hints for what to do are pretty well laid out in the topic. You have to add a buffer or improve the input buffer. Remove C21, jumper R31 and R1, replace R2 with 1M and see how that sounds. This is completely reversible, so if it doesn't work you can restore the pedal to its original state if you work carefully. Please let me know if you succeeded.