Crybaby Input Buffer

[humanbn]

I have found some sites that explain how to bypass this option but nothing that can explain what it's doing. Can anyone point me in the right direction?

[sumgai]

bean,

I wasn't aware that the Crybaby had an option to bypass the input buffer..................

Seems to me that someone, a veritable Einstein perhaps, thought that the input buffer was a bad idea. I'm pretty certain that if this were the case, then any such "mod" would have become widely known long ere now....... after all, the Crybaby has been around for what, sumpin' like 40 years?

I wouldn't monkey with it for one reason only - the impedance mismatch will likely worsen the tone. A buffer is usually used to isolate one stage from another, it shouldn't add or subtract anything from the signal, just keep the impedances matched up as expected. As we've discussed on this Forum many a time, impedance mismatching is usually a disaster waiting to happen, tonally speaking. You might end up with something wunnerful, but Jimmy The Greek, down in Las Vegas......... he isn't making any book on that, to be sure.

Your call, but now you know my humble (!) opinion on the topic.

HTH





sumgai

[humanbn]

Here's a link to the remove buffer mod.

homepage.ntlworld.com/s.castledine/greenfuz/tb4.html


I'm going to try it, see what happens.

[sumgai]

bean,

OMG, that's such a classic "innerweb folklore" snowjob, I can't believe that anyone would fall for that without first checking other sources for corroboration. Oh wait, that's just what you're doing here, isn't it? Good for you!

No, the mistake wasn't the fact that they have added a buffer after some time, it's the fact that the buffer didn't show up until later - it should have been there all along.

Look, you can go ahead and do the job if you wish, but I can tell you exactly what will happen - you'll get the exact same results as you get now, tonally speaking, while in Bypass mode. The reason? It's because you're still loading the signal as it passes through the piece of straight wire that comprises the Bypass circuit. The buffer is intended, in this case, to present a higher impedance to that incoming signal, thus loading the signal less than an un-buffered circuit, and equally thus, robbing no where near as much of your tone.

Remember the definition (posted above) about what a buffer does? That's right, it isolates one stage from another, without coloration (or as little as possible). But here, it's actually meant to reduce, as much as possible, the loading of the input signal in Bypass mode. Simply put, the higher the impedance presented to the signal, the less chance of audible tonal changes. Buffers excel at doing just this, presenting a very high impedance.

I tend to think that the chances of the buffer presenting a lower impedance than the wah circuit itself are pretty dismal. IMO, the engineer who added the circuit was probably smart enough to understand what I just wrote, and designed the buffer circuit with a very high impedance. If he didn't, well, it wouldn't be the first time someone screwed up, eh? But what are the odds?

As usual, where the's a crying need for a simple way to do something, there is a desirably simple solution. Enter the DPDT switch, made to order for truly bypassing a circuit, and all the loading (tone-robbing) said circuit would otherwise induce. It's less trouble, quicker to do, cheaper, and totally reversible as well. Can't be beat - 'nuff sad. ;D


HTH







sumgai

[ashcatlt]

Umm....

Aren't we talking about this

?

Seems to me there is a DPDT switch there. It's kind of tough to say exactly where those wires on the connector actually go when they hit the circuit board, but I'm pretty sure that it's meant to accomplish True Bypass. The True Bypass debate is another topic altogether, one we've discussed around here a couple times. Just a couple threads down, in fact.

My concern is what happens to the circuit when it's not bypassed. Seems to me like that buffer is meant to accomplish two things.

1 - "Protect" the guitar from loading. A low input impedance will change both the cutoff and the resonance of the RLC circuit which is the pickup, pots, and cable.

2 - "Protect" the wah circuit itself. This here is another RLC filter, and I'd think it was pretty deliberately designed to be fed by the relatively low impedance from the buffer transistor. Who knows what's going to happen to that filter when it's suddenly got to contend with this extremely high input Z from the pickups? (Not me...)

[sumgai]

ash,

You're correct, that's a "dual purpose" circuit - it attempts to accomplish two things at once, which gives us the opportunity to divide them out for separate analysis.

The True-Bypass section has been dealt with, quite well to my thinking, so we'll leave that alone for the here-and-now. The attempt to offer a different impedance to the incoming signal, while in wah mode (not in bypass mode) is indeed worthy of consideration here. I don't think I can further enhance what you just said, you were clear and lucid (!), and you did it in near layman's terms. Good job.

Well, I suppose I could make an exception, and say that I like the idea of people experimenting to seek out different tones, but I extremely dislike people who use FelderGarb^™ to explain the how's, why's and wherefore's of what they've done......... that just riles me up sumpin' fierce. Or it saddens me, I can't tell which anymore.

HTH



sumgai

[mr_sooty]

I did the true bypass mod on my ol faithful Vox Wah. I wish I'd read all this first. I don't even know why I did it, as I never noticed any tone suck in the first place. I guess I was just a Lemming falling for the hype.

At first I used a DPDT, which was hopelessly unreliable, so I changed it to a 3PDT, which is much better.

But because my Wah is first in my chain (that's just how it fits best on my board), I now have 'pop's when I turn it on. I know now that I really should have a buffer first in my signal.

Also, my Wah now has this low hum when being powered by an adaptor (which I hook up to the battery clip via a battery clip extension from a daisy chain). I don't know if this is because of the mod or the power supply, because I changed power supplies about the same time as I did the mod. I used to power my wah in a similar way with a different adaptor, no problems. It also doesn't hum when used with a battery.

Unfortunately, this mod is probably not reversable, because it involves clipping a wire. I clipped pretty close to the little white box that all the wires feed into, so I'm not sure if I can re-hook it up again.

I kind of wish I just left it alone. It was perfectly good and I never noticed any tone suck at all. I may sell it to someone who believes the hype and buy one of those new Vox847a versions, with the 9 volt adaptor input.

[humanbn]

I did the true bypass mod to my crybaby gcb95. I didn't take out the input buffer. I can't tell much difference in the sound at all with this mod. The whipple that I installed does a nice job and the blacktop pot is sweet too. I also switched out some of the resistors to bump up the mid range and boost the gain. I like the product that I have now but I don't think I'm quite finished with it. The pedal sounds much better when I'm playing it without any overdrive. Adding some overdrive to the signal seems to decrease the amount of sweep that is apparent. Also, with overdrive, I get a resonance in my cabinet that I don't like. It's almost like the speaker isn't able to handle the signal. This only happens in one part of the sweep. I don't know what's doing but I'm going to keep piddling with it.