The Electra Forums

My X120 Leslie West appears to have the Super Charger add on kit installed, I'm not certain of this, but it seems to match the (foggy) descriptions that I've read:


Resistors added and possibly volume/tone potentiometers changed out (again not sure). This guitar has seen better days, came to me with all three switch tips broken off and missing the volume knob. However the tone knob seems to have some sticker residue on the top, we know that many of the upgraded guitars had stickers put on the knobs after surgery:


This is a picture of my Outlaw MPC innards, older generation by the looks of the pots, I'm assuming this is the stock setup, missing the extra resistors and the cap installed in a different place. (Pot order in all three pics is Vol/Tone/MPC/MPC, you can see the 150kohm pots on the right):


My question is, what did the Super Charger consist of, and what does the kit in fact do? A couple of admissions on my part, I) My ears aren't what they used to be II) I've only had the X120 a couple months III) The pots on the X120 are pretty scratchy so even when I do adjust them, there are more than a few dead spots and weird drop outs. There has been much speculation about this kit on here, and I think the scarce literature about them is laden with marketing superlatives that don't really say too much (if you know what I mean). Keep in mind that many of us don't know the difference between an Audio Taper or a Linear Taper, or what resistors tied to ground do to the signal. Thanks in advance, Mike.

P.S. Bonus question, would SLM change Tone Spectrum 5 way Rotarys to a typical 3 way toggle by request on the Omegas and MPC's? We've heard some tall tales (and some believable ones too) in the sometimes seamy underworld of used guitar sales.

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Electra Guitar Videos ===> http://www.youtube.com/user/mjm33mjm?feature=watch

I'd like to hear Tom weigh in on this.



The 4.7Meg ohm resistors are to help reduce popping and thumping when the effect is switched in or out of the signal path. I don't know if those are part of the Super Charger kit.

So those resistors are not part of the Super Charger kit? I've only seen a handful of MPC control cavities, and didn't know they had gone through revisions. Well that makes me look dumb. Still would like to know what the aim of the SC upgrade was.

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Electra Guitar Videos ===> http://www.youtube.com/user/mjm33mjm?feature=watch

I don't know if they were part of the kit or not. I may have further info shortly.... stay tuned...

the resistors are part of the stock MPC wiring.

http://www.rivercityamps.com/electra/slm1.php

however both of yours look fairly original... interesting....

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My Electra Pages
I have too many projects!

Hello all, I hate to claim ignorance about the SC Kit but I frankly don't remember all of the mods we did over the years. I do know that we changed the pots, installed the damping resistors and modified a lot of stuff in St. Louis to improve the design. The pot change was due to some circuit changes in the modules. At times, there'd be a notch in the pot that would create almost an envelope effect.

As to changing out the 5 way to a 3 way under custom order, ... No. We didn't have that as one our options. I personally did change out a few for potential endorsers that were using the instruments. Some simply were replacing their LP with an MPC and it was easier for them to integrate the Electra of they had a familiar PU selector.

I will do my best on audio Vs linear taper pots. Human ears do not respond to volume changes in a linear way. For instance it takes more energy to change from 90db to 91 db than from 80db to 81 db, noting that the decibel scale (db) is tuned to human resonse. Linear pots will give you a smooth response to change but our ears will not hear it that way. An audio taper pot takes our response into acount and makes for a smoothe signal.

I have an Acoustic Control bass amp that uses linear pots for volume. The difference between 1 and 2 is that of home studio to club gig. I have never had it above 3

I don't know if the above holds true for tone perception.

Here is all I have or can find on it. There are 2 pages and they take forever to load. Please be patient. Maybe someone copy it, crop it, pretty it up, and put it on the website?

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Thorny

Oh yeah, I put the values on the pots, they were not there!

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Thorny

Thanks for those wiring diagram scans. I thought I'd seen the Super Charger on non-MPC guitars, but maybe not. I'm very skeptical of the claims:

15. You should notice more output, better high frequency response, more definition of low notes and improved balance.

Really? I could understand the high frequency boost as electronics seems to eat up high end, but more output? And what exactly does 'more definition of low notes' mean? Improved Balance? Compared to what? Sounds like a lot of marketing jargon to me. Also looks like a lot of work...

I'm disappointed that Electra never used or offered (to my knowledge) a Treble Bleed circuit. You tend to loose a lot of high end 'brightness' when you turn down the volume pot, and a capacitor between the two pins on the volume pot allows a certain amount of high frequencies to 'bleed' through when you turn the volume down. G&L had these stock in the early 80's as did Peavey, and I'm sure other manufacturers had it available. Very useful live, you can turn the guitar down for clean passages (without losing high end) and still have the ability to crank it out for solos or more distorted stuff.



P.S. I bet Paul could resize and repost those scans (hint hint!)

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Electra Guitar Videos ===> http://www.youtube.com/user/mjm33mjm?feature=watch

Yeah, I was never really convinced it truly changed much of anything. My vote was for it was a an upgrade or fix for something with some clever marketing hype attached. Unless, by chance a batch came out with lower pot values or something of that nature. A 250K volume pot would attenuate the signal, roll off high end and clarity, so putting a 500K in would help.

I know, I had a peavey oddysey - a killer guitar when they first started making them and it seemed they wanted to compete with PRS and other boutique builders. I couldn't get good tone out of it and didn't understand it. I changed pickups at least to two different sets, and all sounded like junk. Then I found out Peavey put 50K pots in there instead of 500K - duh! No wonder everything sounded terrible. I put new pots in the guitar and it was FANTASTIC (except for that tiny little neck - that was something I couldn't easily fix so it was sold). I overlooked the obvious.

Stuff like that happens all the time. Pick up a late 50s to mid 60s Gibson tube amp and you have about a 30-50% chance there is a wiring or parts problem in the amp from the factory (it is NOT uncommon and I think it is the reason why they never were popular like Fender amps were). I had one for years with an odd problem but none of the usual suspects revealed the problem. We had to go over the schematic piece by piece. It turned out to be wrong from the factory. We just found it after about 50 years or so later.

As far as a treble bleed cap on the volume pot, yeah lots of makers do that. Ibanez does it. With just a treble bleed cap alone it can sound kind of "waspy" when you turn down though. The treble can be too loud at very low volumes. A better solution is a cap and resistor together that seems to give you a bit more middle of the road effect. Reverend does that, and many others do now too. I think guitar nuts or some other site has some suggested values. Maybe even reverend does. I don't recall. Some say if you use particular paper in oil caps and better pots (RS makes kits) that they won't bleed the treble off and the whole thing sounds better. I know that some guitars seem to have the problem pretty badly and other don't. I haven't really determined to my satisfaction that this is true or not. This LP I just picked up has Hovland Musicaps in it (super expensive) and it really does not sound any better to me. I don't know what pots are in there. I put some PIO caps in another guitar and I don't think I hear any improvement. I can DEFINITELY hear a difference in the cap types in a guitar amp though.

I am off on a tangent again.

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Thorny

Keep the tangents comming they are very informative.

Here's the best shots I can get of my X720 supercharge - Looks like an official factory install to me. My battery pull thing says 7-1-79.

Four 4.7 meg resistors for $1.40 and 10 minutes of solder time persuaded me to do my newly acquired X730. I believe there may be a miniscule difference in sound - still hard to tell for sure. I believe it did knock out the pop from activating the MPC switches though.