New at runoffgroove.com: 22/7

[B Tremblay]

22/7 is a CMOS-based version of the Big Muff Pi.  Check it out: http://runoffgroove.com/22-7.html

Three clips are available on the Sounds page: http://runoffgroove.com/salvo.html#227

We've also added an article describing construction of a pinout-matching module for the 4069 CMOS chip.  Build one and use the 4069 in 4049-based layouts: http://runoffgroove.com/6949.html

[spaceace76]

awesome! this is definitely going on the list 

[Ben N]

How does this compare to earlier versions of the 22/7? There used to be a switched filter in the input stage (rev. 1.3, schem by gaussmarkov). What happened to that?

[John Lyons]

The PCB ordering page will be up soon.

John

[petemoore]

  +1, on CMOS Big Muff  and the clips ! Very cool !
 ..just when the BMP has finally taken a position of prominence on my PB..

[Paul Marossy]

Interesting idea. Sounds pretty cool.

[WGTP]

Brilliant.

Also, the 14pin 74HCU04 suggested by Tim Escobedo is a good chip to use.  Don't forget to try LED's as well.   

[gigimarga]

Very interesting...thx a lot B. Tremblay!

I've built sometime ago an earlier version, but it had too much hiss. Is this version better from this point of view?

[stm]

How does this compare to earlier versions of the 22/7? There used to be a switched filter in the input stage (rev. 1.3, schem by gaussmarkov). What happened to that?

The early versions had a BOOST switch at the input.  It provided more gain than a stock BMP, but it also raised the noise floor and produced too much trouble with hum and oscillation, therefore it was discarded in later revisions.  Besides that, is wasn't a filter per se, as it didn't affect the frequency response in the audio band.  More to read here: http://www.diystompboxes.com/smfforum/index.php?topic=55237.msg424565#msg424565

The new circuit has a three-position switch in the tonestack that provides two additional sounds apart from the CLASSIS tonestack.  The SCOOP mode has a deeper notch, but not as much as the one found in the Swollen Pickle, as we found this setting too extreme and introduced an appreciable attenuation as well.  Nevertheless, if a deeper notch is desired, it is a matter of replacing the 10n extra cap with a 22n cap, or even a 33n cap (which would produce the notch depth as in the S.P.  The FLAT mode is a very nice addition, as it produces a sound that can cut its way through the band nicely, especially for leads and solos.

A final note, I just noticed the early schems (1.2, 1.3) in the contest threads are gone.  I didn't take them down on purpose; they were hosted at tynipic.com and apparently they were removed due to a long period of inactivity.  Please refer to the official release now.

P.D.  The 4049 to 4069 adapter module adds the possibility to answer the old question: Is there an audible difference between a 4049 and a 4069?  After all, the output current capabilities are different, so it is very likely that it should have a sonic impact somehow.

[Mark Hammer]

Looks blissfully simple, and sounds great.  I'm just happy that Divide-By-13 didn't produce it, or else the folks in the music stores would be in trouble:"Hi, do you have the 22-divided-by-13, over 7, pedal?  or maybe it's the 7-divided by 13/22.  Wait a sec, I have it written down here somewhere."

[stm]

Looks blissfully simple, and sounds great.  I'm just happy that Divide-By-13 didn't produce it, or else the folks in the music stores would be in trouble:"Hi, do you have the 22-divided-by-13, over 7, pedal?  or maybe it's the 7-divided by 13/22.  Wait a sec, I have it written down here somewhere."

:-)

[Stompin Tom]

Cool. It's on my list. I'm glad to see you guys are still working on new builds!

[mnordbye]

Sounds great, man!

[Brymus]

WOW that sounded sweet! Very 1969
Thanx ROG for another great circuit,and thanx John for the transfer layout.
Also the tut on the 4049-4069 was really nice too.Should be helpful to lots of people who use the 4049 in pedals.
I look forward to the next build you guys post 

[oldrocker]

Thanks again R.O.G.  You rock!

[tol]

Here's my 22/7 built with a sweet basicaudio pcb. Has anybody had any success in lowering the noise in their build? I really love the sound and 'feel' of the pedal. John was saying it's thermal noise rather than power line noise. I am going to try a larger value cap instead of the 100uf to see if it minimizes any hum/hiss but is there somewhere else we should be looking? In a typical bmp there are 470-560pf caps in the clipping stages to block dc. Should we be changing some values there?

There is a discussion on thermal noise from last March here:

http://www.diystompboxes.com/smfforum/index.php?topic=75340.0

[John Lyons]

Mine is noisy as well. It sounds like thermal noise but I don't know for sure.
Sounds like listening to a large waterfall with your hands covering your ears.
A pink noise if you will. Full frequency noise as you can here low mid and high end hiss.
It's about 3 times as loud of as the big muff variants I've compared it to.

I get relatively little hum or outside noise, just the constant hiss.
With the gain lowered it's less but even with the "sustain" all the way off
It's still there just lower. I'm using all metal film resistors so I don't think
it's thermal noise in the resistors.
I have used 2 different brands and prefixes of 4049 ICs with the same result.
I built a second one just to be sure, same deal.

Is this IC related? I seem to remember the Red Llama being noisy as well.
Other than the noise this thing rocks!

Any ideas?

John

[linny1982]

just finished putting mine together with the basic audio layout. sounds awesome and no noise even with switchmode wallwarts on the same powerboard as my pc. running it through my valvecaster into a 50w ss combo and the sound is HUGE (seymour duncan invader pup helps..)

[tol]

OK so I replaced the 100uf cap with a 220uf and I fancy I hear less noise especially in the low end but I may just be fooling myself. Will somebody try it on theirs and tell me I'm crazy?

[John Lyons]

Just tried it but didn't hear any difference.
That cap is a reservoir cap to smooth DC ripple
that may be in the line after the typical 1000uf
smoothing cap in you AC adaptor power supply.
It's a local, sort of buffer of DC power...

I need to audio probe the board again...