Memphis - Tremolo Modulator

Barcode · Post by **Barcode** » 01 Mar 2008, 19:06

Shockingly great sounding pedal from Memphis. Guts and PCB, I'd like to trace a schem.

Interesting to me is the number of wasted traces and empty holes. Clearly they manufactured 2 or 3 boards and built different effects by populating different areas, but i wonder what else they made with this board.

EDIT: forgot to mention that this is AFTER i already true bypassed it, it had the usual spdt switch from the 70's.

Dirk_Hendrik · Post by **Dirk_Hendrik** » 01 Mar 2008, 19:19

The way the jacks are mounted has a striking resemblance to the Coron Jet Flanger & Filter Matrix!

analogguru · Post by **analogguru** » 02 Mar 2008, 00:20

Interesting to me is the number of wasted traces and empty holes. Clearly they manufactured 2 or 3 boards and built different effects by populating different areas, but i wonder what else they made with this board.

phasers....

The picture below is from a Coron 70 "Space Machine".

When you compare it, you will see that you have a mistake in your wiring in that way that the capacitor beside the IC near the footswitch shouldn´t have a contact to footswitch...
I think you will hear the ticking of the LFo at the moment...

Barcode · Post by **Barcode** » 10 Mar 2008, 06:28

analogguru wrote:
Interesting to me is the number of wasted traces and empty holes. Clearly they manufactured 2 or 3 boards and built different effects by populating different areas, but i wonder what else they made with this board.
phasers....

The picture below is from a Coron 70 "Space Machine".

When you compare it, you will see that you have a mistake in your wiring in that way that the capacitor beside the IC near the footswitch shouldn´t have a contact to footswitch...
I think you will hear the ticking of the LFo at the moment...

hmm, quite confused by what you say guru, as the original switch quite clearly connects there and I received no ticking, actually oddly enough the pedal was quiet as a mouse, and pleasingly choppy.

analogguru · Post by **analogguru** » 10 Mar 2008, 07:21

The wire of the switch is not only soldered to the according pad it is also soldered to the neighbour-pad of the capacitor.

analogguru

Barcode · Post by **Barcode** » 10 Mar 2008, 07:35

analogguru wrote:The wire of the switch is not only soldered to the according pad it is also soldered to the neighbour-pad of the capacitor.

analogguru

oh i see what you mean. no, picture defect. the two pads are not actually connected. by the way, those are some odd part numbers, what do you think suitable common replacements would be? all the IC's are the same and all the trannies are the same. possibly a 741 variant for the IC's? seems to be in the family. I'm figuring likely the two trannies would be subbed with general purpose NPN trans, i can't imagine they are fets or special transistors.

analogguru · Post by **analogguru** » 10 Mar 2008, 07:56

The diode is a Zener-diode probably 4,7 V or 5,1 V - must be written on it.
The transistor marked K92 is a 2SK 92 - a Fet comparable to 2SK 30A
The other transistor is a PNP-trannsistor - can´t read what´s written on it, probably Axxx (=2SA xxx).
The chips are NEC µPC 741 C which are 741.

I am missing some component values, especially from the capacitors. If I get them I can finish the prepared schematic.

analogguru

Barcode · Post by **Barcode** » 10 Mar 2008, 08:11

analogguru wrote:The diode is a Zener-diode probably 4,7 V or 5,1 V - must be written on it.
The transistor marked K92 is a 2SK 92 - a Fet comparable to 2SK 30A
The other transistor is a PNP-trannsistor - can´t read what´s written on it, probably Axxx (=2SA xxx).
The chips are NEC µPC 741 C which are 741.

I am missing some component values, especially from the capacitors. If I get them I can finish the prepared schematic.

analogguru

I've given the pedal back, but have easy access to it. i'll try to get it back within the next day or two and get you what values you need. Then once you have a schem, I'll have a try at the layout. could probably sub in 2n5457 for the fet, no?

bajaman · Post by **bajaman** » 10 Mar 2008, 08:13

great team work guys

bajaman

analogguru · Post by **analogguru** » 10 Mar 2008, 09:13

Barcode wrote:I've given the pedal back,....

I thought, that YOU yourself:

Barcode wrote:...like to trace a schem.

So for this reason i waited for your results....

but now...without component values ?

The schematic is really funny and more intersting than any bootweak-pedal:
It is a "one-stage phaser"...
and for this will sound a bit like a vibrato.

analogguru

Barcode · Post by **Barcode** » 10 Mar 2008, 10:56

analogguru wrote:
Barcode wrote:I've given the pedal back,....
I thought, that YOU yourself:

Barcode wrote:...like to trace a schem.
So for this reason i waited for your results....
but now...without component values ?

The schematic is really funny and more intersting than any bootweak-pedal:
It is a "one-stage phaser"...
and for this will sound a bit like a vibrato.

analogguru

i was still planning on it, but i got the impression from your last post that you had worked a schem up minus a few values. but i can get the pedal back and start a-tracin'. you are right, it is quite a unique little tremolo. it's like it throws an out of phase signal in at regular intervals to cancel out the original signal to produce the trem.

Brian M · Post by **Brian M** » 10 Mar 2008, 11:13

analogguru wrote:
Barcode wrote:I've given the pedal back,....
I thought, that YOU yourself:

Barcode wrote:...like to trace a schem.
So for this reason i waited for your results....
but now...without component values ?

The schematic is really funny and more intersting than any bootweak-pedal:
It is a "one-stage phaser"...
and for this will sound a bit like a vibrato.

analogguru

i think the red witch tremolo does something like that. At least that's the rumor. Never tried it my self.

Weren't all these pedals actually made in japan? That is what i had always thought. I always thought that was funny since they were named after an american city (although i suppose it could have been named after the ancient egyptian city) I remember seeing them practically brand new in pawn shops in the late 80's and no one wanted them... of course everyone thought the rockman stuff was awesome back then

analogguru · Post by **analogguru** » 10 Mar 2008, 11:27

Made by Coron, sold under different brand names like Asama, Grant, Memphis, Nashville, Storm... whatever you wanted to have printed on them.

analogguru

Brian M · Post by **Brian M** » 10 Mar 2008, 11:33

analogguru wrote:Made by Coron, sold under different brand names like Asama, Grant, Memphis, Nashville, Storm... whatever you wanted to have printed on them.

analogguru

never would have guessed that... the coron stuff i am vaguely familiar with were all black and looked like a DOD fx series pedal... of course those had plenty of different names on them as well... Probably more familiar with those, because i didnt pick up a guitar until 1989 or so.

Barcode · Post by **Barcode** » 11 Mar 2008, 01:12

Brian M wrote:
analogguru wrote:Made by Coron, sold under different brand names like Asama, Grant, Memphis, Nashville, Storm... whatever you wanted to have printed on them.

analogguru
never would have guessed that... the coron stuff i am vaguely familiar with were all black and looked like a DOD fx series pedal... of course those had plenty of different names on them as well... Probably more familiar with those, because i didnt pick up a guitar until 1989 or so.

you are correct that they are made in japan, it is stamped on the box.

Brian M · Post by **Brian M** » 11 Mar 2008, 02:32

Barcode wrote:
Brian M wrote:
analogguru wrote:Made by Coron, sold under different brand names like Asama, Grant, Memphis, Nashville, Storm... whatever you wanted to have printed on them.

analogguru
never would have guessed that... the coron stuff i am vaguely familiar with were all black and looked like a DOD fx series pedal... of course those had plenty of different names on them as well... Probably more familiar with those, because i didnt pick up a guitar until 1989 or so.
you are correct that they are made in japan, it is stamped on the box.

You know, sometimes i wish i could go back in time and kick my self in the butt for not loading up on stuff from pawn shops like this. The local place had a bunch of the nashville pedals for $15 to $20 each... but a boat load of the newer black 80's coron pedals... I was funny too, since they seemed to have 20 different brand names on them... washburn, sound city among others. Then again, i was dirt poor back then.

GT45 · Post by **GT45** » 25 Sep 2008, 16:27

Newbie here looking for a Coron Space Machine or schematic, or a similar sounding easier-to-find pedal?

Any and all suggestions welcomed, and I have a few things I could post gut shots of if anyone's interested (ross stereo analog delay and dod 585-b, for starters)

thanks!
GT

PurplePeopleEater · Post by **PurplePeopleEater** » 18 Dec 2008, 16:48

any progress on the tremolo schematic ?

Barcode · Post by **Barcode** » 18 Dec 2008, 16:51

PurplePeopleEater wrote:any progress on the tremolo schematic ?

well, the friend that owned the pedal moved away before I could get it back from him. I should be seeing him soon though, will update.

Harold · Post by **Harold** » 06 Sep 2012, 18:36

Barcode wrote:
PurplePeopleEater wrote:any progress on the tremolo schematic ?
well, the friend that owned the pedal moved away before I could get it back from him. I should be seeing him soon though, will update.

I have a Coron Sound Cutter 60, which should be identical to the Memphis Tremolo Modulator acoording to this: http://www.effectsdatabase.com/model/me ... omodulator

I already planned to draw a schematic of it, but that's a skill I don't really own ... yet!