My weener needs help

[joegagan]

hell yeah. that is good news

[ch1naski]

hell yeah. that is good news

Thanks, Joe. I've got most of the component suggestions from this thread printed out, and (way too many) sockets on the PCB so I can do a little experimenting with it all. It is a VERY deep sweep right now, and really loud compared to my vox (my usual favorite, it's been tweaked). Looking forward to it now that that frustration is over with.

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[joegagan]

it's easy to make a wah quieter or kill off a little treble. it is not so easy to make it louder without getting dirty or get more treble if the sweep is set to low.

one other myth from the internet. that idea that changing the .2 to a .3 on the pot cap will simulate icar taper, real world and spice modeling have both shown this to not be the case very often. in fact, the value of these caps hardly matters at all in most wah configs. in rare cases, raising the one off the C of Q1 up to .7  to .9u can even out the freq plot if there are dead spots.

[ch1naski]

So.... I put the freq pot back in (100k linear), just to hear the difference of having it in versus out of the circuit. It's really only effective for the last quarter turn, where the bass frequencies get extreme. Almost ineffective after that.
When the bass gets extreme, the volume drop is more noticeable.
Need to find a way to keep the sweep level more consistent throughout the range.

Also added a 1k Lin pot with a 1.5k resistor in parallel to get 590 ohms max on it and wired it at R4 for a gain control. Now with the gain up high, the buffer will make a clicking sound. Turn the gain down a bit, and it goes away.



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[octa805]

can't wait to grab my weener again and tweak it this weekend!

think I'll start by pulling the trimpots and going from there. what should I put in R2 & R5?

[ch1naski]

can't wait to grab my weener again and tweak it this weekend!

think I'll start by pulling the trimpots and going from there. what should I put in R2 & R5?

my advice would be useless, since I am not happy with mine yet.

It might be useful to know which component limits the amount of bass frequency in the sweep, and which one limits the high frequencies.  That would let me then concentrate on the peak of the sweep, and gain overall.
That's my thinking, I don't know if it's that simple.

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[octa805]

I just need more quack. I'm a quack addict

[ch1naski]

I've been looking at rg keen's technology of the wah articlehttp://www.geofex.com/article_folders/wahpedl/wahped.htm#basicmod, and noticed that the Rfb resistor (r5 on our wah) is undefined as to what changing it affects.

But I've gained a little more understanding of what does what.

So far tho, no weener love.

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[ch1naski]

Getting frustrated with this. Does anyone have a demo of this build, stock? I'd like to hear it, I've heard Jake's, but his is modded to his spec. I think it doesn't have much in the way of mid frequencies..it goes straight from booming bass to slightly more high freqs than bypassed. And that lack if mid body makes it seem like a volume drop.

[octa805]

Jumping back in on this today hopefully.

Are these the jakefuzz tweaks here?

http://www.madbeanpedals.com/forum/index.php?topic=3685.0

[JakeFuzz]

Hey Octa, I just got back from Chicago yesterday (Chicago is now one of my favorite cities!). Let me crack open my weener this afternoon and take some voltage readings for you. I can also grab all of the component changes I made since then.

[octa805]

Hey Octa, I just got back from Chicago yesterday (Chicago is now one of my favorite cities!). Let me crack open my weener this afternoon and take some voltage readings for you. I can also grab all of the component changes I made since then.

that's awesome! Chicago is great for food & music. appreciate the help

[JakeFuzz]

Okay the specs as they are right now:

C1 = 15nF (at the time that demo was recorded I believe it was 100n though and it might go back to that value soon)

C6 = Short

C5 = Open

Capacitor selector across FREQ lugs 2 and 3

R4 = 220R

R5 = 1.5K

R2 = 47K (at the time of demo this was 68K I believe)

C2 = 4.7uF (the really small gold Nichicon audio electro)

C4 = 330nF

R12 = Lifted open (at the time of demo this was connected)

Q3 = Pulled (at the time of demo this was a 2n5457)

Q1 = 2n2925 (Timbo's) hfe = 180

Q2 = 2n2925 (Timbo's) hfe = 131

Sweep pot is just the standard Vox 100K pot from the V847

Inductor is a Whipple

Idle voltages:

Q1:
E - 0.03
B - 0.59
C - 4.12

Q2:
E - 2.57
B - 3.03
C - 8.78

I am sure those are all the changes. I tend to move values around quite a bit. The feedback capacitor almost always stays on 15nF. I may end up trying to go with a higher gain device in Q2 and see if that does anything, I cant remember why I chose such a low gain for that position. I am probably going to bump up the input capacitor to 47nF or higher just because. My peak trimmer is always set to about the center.

[octa805]

Wow. Thanks!

Do you just have nothing in C6?

[JakeFuzz]

C6 is shorted so it is just a jumper. C5 is open so it has nothing in it. I don't really remember why I did it that way. I think it was because the frequency pot was closer to where I was going to put the cap selector anyways so I decided to reduce my wiring a bit. It is pretty much the equivalent of having a capacitor selector in place of C5 if you don't want to do it this way.

And now that I think about it if you really want, I have a spectrum analyzer in my lab at work. I can actually get a frequency response plot of the wah in different positions to see what the frequency content of this weener is. I think would just be overkill though.