MXR blue box wierdness ??

[MartyMart]

http://www.pbase.com/image/44598209

This is one from several weeks ago, here's the board pic before the
wire-up, its "almost" working, ie: it fuzzes and octaves, though the
tracking is a little "odd" ! but its like a quater of the volume of other builds, at best , in fact more like a tenth !!!
Any ideas as to what's up here ?
I've done all the de-bugging that I can think of, and have found no
errors in the vero build, its as per the tonepad schem, just minus a few
of the "re-issue" parts that are not required anyway.
http://www.tonepad.com/project.asp?id=33
For all the 56k's I used 47k's otherwise all as is ....
The chips are an NE5532AP and a HEF4013BP....
Thanks for any insight into the volume loss

Marty.

[MartyMart]

Er.... Bump ...... anyone .... ??

Marty.

[hank reynolds 3rd]

I think the blue box, reissue or no, has a low output...my clone is pretty much the same...it goes to about the same volume as the bypassed signal when at maximum volume...the tracking can be pretty shitty also, but thats why i like it  

Cheers
Sam

[LivingDeadPunk]

I tried an original MXR blue box some time ago and the tracking was more than random, it's the way it's meant to be, it is actually better on my clone.

I like the "wierdness" but if you want to improve the tracking you could try a compressor before the blue box, I use an orange squeezer when I want a real octave down fuzz instead of a crazy synth effect and it works perfectly.

On my clone the output is a bit louder than the bypass signal when the volume pot is cranked to max. I used a TL072 instead of the RC4558  2N5088 instead of the 2N3904 and I changed the 50k blend pot for a 100k lin pot.


Hope it helps

[MartyMart]

Thanks for the replies guy's, however the signal is at least a quater of
the bypassed signals level.....
I must have a problem "somewhere"  ??

Marty.

[Fret Wire]

I can't help but wonder if the 56k (47k) subs may have something to do with it.

[robbiemcm]

Could someone explain to me why you wouldn'y be able to put a trimpot on the bypassed section acting like a volume pot. Then some cleanboost before that. Woudln't that work?

[MartyMart]

UPDATE :
Fretwire was in part correct, I have rewired the blue box and now used
all 56k resistors as I should have !
In general the sound is much better however.....
I have a kind of "intermitent" loss of signal, sounds like a "gated digital"
thing going on, rather than a loose wire, if you get my meaning ...
Any clues ... as its almost there  !! ??
Perhaps re-do the 4013 daughter board section .....
one thing, I dont have all the "grounded" 4013 connections going to ground separately, they "link" and then link to ground ... problem ?

Thanks,
Marty.

[hank reynolds 3rd]

If you mean a kind of splutter and dying out of notes, as well as some low volume burbling when not plucking the strings, then i think its supposed to do that aswell (well,mine does that)...there was some mods for a gate pot that were posted ages ago in the old forum,but i can't seem to find them in the search field...i think it was something along the lines of changing a resistor after the first opamp for a 470k pot wired as a variable res....don't quote me on it tho....

Cheers
Sam

[MartyMart]

If you mean a kind of splutter and dying out of notes, as well as some low volume burbling when not plucking the strings, then i think its supposed to do that aswell (well,mine does that)...there was some mods for a gate pot that were posted ages ago in the old forum,but i can't seem to find them in the search field...i think it was something along the lines of changing a resistor after the first opamp for a 470k pot wired as a variable res....don't quote me on it tho....

Cheers
Sam

Thanks sam,
It's worse than that, complete loss of signal for a split second or so
then back to normal, with an almost "ramped up" start again !!

....... ??

Marty.

[Fret Wire]

I don't think that ckt is very IC specific with IC1. I think all the usual suspects will work. You could always try a TL072. Same for IC2, I don't see any different UB/B types with the 4013, like the 4049 types have. Did you check the data sheet for your specific brand of 4013 against a Texas or Fairchild? I'd probably re-check all the 4013 connections (pinouts) again, as well as the grounding scheme. The "reissue parts" are power supply filtering. That might throw the 4013 for a loop if a non-filtered ps was used.

When you've got that puppy all straight, you can try Mark Hammer's selectable octive and tone mods.
http://diystompboxes.com/sboxforum/viewtopic.php?t=22917&highlight=mxr+bluebox

[hank reynolds 3rd]

Im guessing its a solder brige/loose connection/a crack in the trace going off youre description^
I settled for an 082 opamp and bc550 or 2904s,with a & oct or é down switch (its in the search bit) the trannies seemed to affect the volume/fuzzyness and biasing/ sputter of the oct down..i got mine quite growly with splutter at the end (i like that crackly effect)

Ill have a look over the weekend (im just on my way home from travelling europe for the last two months....ive got my guitar but i miss all my pedals!!!)

ill see if i can find the notes on the gate knob mod aswell ( i have 2 bluebox clones, and im gonna add it to the second meself)

Cheers
Sam

Oh ,I also used those red polyester caps from craplins which probably affect something or other... sorry for the ramble; Ive been on too many overnight trains and im living off redbull at the mo...........