deluxe big muff problem... maybe someone can help?

[space_cake]

hey everyone, someone told me that this is the forum to ask all my guitar effect related questions and so it seems. i searched the forum for a possible similar post but found nothing but a wrong scematic of the deluxe big muff.

i got my deluxe big muff from a friend and it had a few problems:
1. the effect won't go off and will leake when bypassed
2. you have to set the volume very high to match the clean volume of the guitar
3. when the compressor section's "release" knob is set anywhere but minimum it starts to make a phase like sound as as i turn it up the phase sound gets longer. when i play a chord and mute the strings i can hear it very well.

i have a little know how in electronics so i opened up the unit and checked a few capacitors and changed the two power filtering caps. the others look to be ok. i also checked for the OA voltages (there are 3 4558 by RCA, CA3080, LM741 & LM1458) and everything seems to be fine. i swapped the 2M5087 trnasistors for new ones as well. the effect does not leak when bypassed anymore but the volume is still has to be set pretty high to get a good sound but that might be normal (?). the main problem which is phasing problem when the release pot is set high and all the same. what should i check (diodes??). i don't have a schematic for this and what i found online is not the same at all. i will appreciate any help!

[nelson]

Hi Space_cake

Welcome to the forum!


Read the sticky thread "what to do when it doesnt work". Follow the instructions.

Also, for two purposes board pictures would be cool if possible. Both copper side and component side.

A) to check the schematic I have against your unit and B) to see if there is anything obvious wrong with the pedal.

I havent seen a schematic for the "Soul preacher" compressor pedal which is supposed to be the compressor part of the circuit.

Is this the version with the series/parallel switch?

[space_cake]

i can take a few pictures, any idea where can i host them?

[Arn C.]

http://photobucket.com/

[Mark Hammer]

There is some information on the inner workings of the Deluxe in this issue of DEVICE.   http://ampage.org/hammer/files/Device1-7.PDF

The Deluxe is a relatively elderly unit, which can imply a few things:

1) Electrolytic caps that are not up to spec anymore.  Not especially likely, but not impossible after 25 years.
2) Trimpot (if there are any) that may have come loose from their moorings after several decades of being kicked relentlyessly by those always-so-emotional musicians.
3) Dirt or other contact-continuity issue in a pot, or switch.

[scaesic]

1. the effect won't go off and will leake when bypassed
2. you have to set the volume very high to match the clean volume of the guitar

these two symptoms scream broken switch, so at least check it for continuity before anything else.

[Mark Hammer]

That may be true of more contemporary units where there were a variety of production runs.  The ancient ones (and the Deluxe probably hasn't been made since 1982 at the latest) probably don't have the switch-related issues that more modern units have....unless E-H made bad switch choices in the late 1970's.

[scaesic]

That may be true of more contemporary units where there were a variety of production runs.  The ancient ones (and the Deluxe probably hasn't been made since 1982 at the latest) probably don't have the switch-related issues that more modern units have....unless E-H made bad switch choices in the late 1970's.

i wouldn't put ANYTHING past e-h.

[space_cake]

hey,

i managed to get some pictures up. board looks ok to me as much as a EH board can.

[space_cake]

i have checked the switches and they work fine. the stomp switch a SPDT by carling and years ago they were made well, the small ON/OFF switch and COMPRESSOR ON/OFF switches are OK as well (made by stackpole). the unit has an internal transformer which i am not sure about but it rattles and prodocues a hum sound but with the threshold knob turned down the unit sound as good as an OP muff can sound. what is interesting is that the phase effect is happening when the compressor is both connected or disconnected. maybe that is a hint towards the problem?

[Mark Hammer]

I found a schematic for the Deluxe that was drawn two years ago by "Tomboy" (who has also contributed a number of schematics and layouts for Marcos/Munk's site and posts here intermittently.)  I've posted it at photobucket but will take it down tomorrow: http://img.photobucket.com/albums/v474/mhammer/bigmuffdlx.gif

Several caveats:

1) The original from Tomboy is a big jpg that exceeds allowable image file size at photobucket so I converted it to a smaller lower-res B&W image that omits the big "Preview Only" watermark on the image.  It is only fair to Tomboy to draw attention to the fact that s/he was not personally convinced of the accuracy of the drawing.  That may have been rectified, but what I posted is a tentative drawing, courtesy of someone who was generous enough to draw and considerate enough to let us all know not to lean on it too heavily.

2) There is a conspicuous absence of a 3080 anywhere in this drawing.  Moreover, the BMP portion does not use two sets of clipping diodes but uses a single 3+3 complement.  Both of these features would make it a mismatch for yours.

One of the things that has not been ascertained yet is whether yours is the "Blend" model or the "Series/Parallel" model.

[Processaurus]

An easy thing to try that has worked on reviving a couple vintage efects in the past for me is re-melting each solder joint and putting a little bit of fresh solder on, so that each joint is shiny again.  Sometimes there was an existing cold solder joint that worked for years, that finally stopped.

Is that a factory mod of some sort with the two resistors and cap on the bottom of the board?

[Mark Hammer]

Is that a factory mod of some sort with the two resistors and cap on the bottom of the board?

When Neil Young showed up to sing on one of those benefit-type recordings 10 or so years ago (I believe it was the Canadian tune "Tears are not enough"), the producer couldn't help but notice that Neil was a little reedy and a little flat.  When he commented on this and suggested another take, Neil responded sardonicly with "That's my style, man".

The "flying components" on the bottom?  That's their style, man.  Or at least it was during the first life of E-H.  My Y-Triggered Filter has some "last minute embellishments" in a very similar style.  Now that E-H has entered the realm of surface mount stuff, I don't think we'll see much more of it though - the components sorta need long leads to be able to do that. 

[space_cake]

blend model?

what should i check so i'll know what model it is?

[space_cake]

it seems to me that the schematic posted here is not of this version of the deluxe big muff by the way.

[Processaurus]

 some talk about the 2 versions:

http://electroharmonix.ronsound.com/articles/bigmuff.html

When Neil Young showed up to sing on one of those benefit-type recordings 10 or so years ago (I believe it was the Canadian tune "Tears are not enough"), the producer couldn't help but notice that Neil was a little reedy and a little flat.  When he commented on this and suggested another take, Neil responded sardonicly with "That's my style, man".

Awsome.  Imagine after Neil walks into the control room and says, "that one's a keeper", having the nerve to look him in the eye and ask,"why don't you try it again?"  Oh man.

[space_cake]

OK - my model is the "blend" model. what next? anyone have an idea what couse this problem?

[space_cake]

trying to keep the post active 

[space_cake]

i recorded a 30sec sample where you can hear the big muff with the problem, anyone knows a place i can upload it to? maybe by hearing it someone will know what the problem might be? i'm pretty sure it's got to do with the compressor section only. i also noticed that the bleeding when bypassed (not the bif muff distortion) in only of the "release sound" and no distortion added.

[Mark Hammer]

blend model?

what should i check so i'll know what model it is?

There are likely other identifiers as well, but the key one is the labelling on the slide switch in the corner.  On one model it says "Blend" and on the later issue it says "Series/Parallel".