May have a new one for you, Dino.

[Mark Hammer]

Meeting up with a fellow later this afternoon to purchase a Korg PME-40X system from him.  In addition to the console that provides the power and switching, he has the compressor, distortion, phaser and octave V modules, plus a blank one for external routing.  I'm particularly interested in the Octave V module, that has octave up, octave down, 1.5 octaves down (divide by 3) and 2 octaves down, as well as adjustable "distortion" for each voice.  I'm guessing that, since such derived tones are generally square waves, the "distortion" controls simply roll off the top end to mellow them.

Almost 40 year-old technology, but I'm eagerly looking forward to it.  I have the Waveshaper module from the series that I have rehoused, but kept the module enclosure and can re-rehouse it.

Looking forward to this.

[digi2t]

Nice! I remember those. I see them on Ebay and Reverb from time to time. In varying conditions, typically not so great though. I would be interested in seeing what makes them tick.

Sidebar; We really do need a "Oh shit... look what I just bought!" thread. And I don't mean in a necessarily good way either. I'll explain....

Over the years, I've developed a habit whenever I'm noodling on the interweb of typing in keywords of stuff that I've always lusted over, just to see what's floating around on the market. I'll type in something like "Traynor YGL-3", or "rare fuzz", or the like, and then look around for a bargain. Well, one of those "catch words" (for a long time) was "Peavey Roadmaster". Not the later 160w version, but the earlier Super Festival 200w monster. Over the years I would catch one here and there. Just the head, or just the 4x12 cab. Even on rarer occasions, the whole enchilada. Generally in fair to rough shape, but it was akin to seeing Bigfoot. In any case, generally priced way beyond my reach, and located even further away, so shipping cost would have equalled the GDP of a small country.

Well... a funny thing happened on the way to the forum....

I'm slacking on the couch the other night, with reruns of House hunters international droning on in the background. I'm conducting my ritual internet cruising, and lo and behold... hark! what do my eyes fall upon? Peavey Super Festival Roadmaster, with matching 4x12 speaker cab.

One eyebrow goes up.

Location: Montreal.

Other eyebrow goes up.

Price: $1000, or make an offer. (For those of you not in the know, the words "make an offer" is like catnip to a Greek. I shit you not.)

Like a lawyer combing through the fine print of a merger contract, I read the ad description. Repeatedly. Savoring every word.

This is a rare find. A Peavey Roadmaster Super Festival Series Amp and matching Mod.412 2 ohm 200 Watt speaker cab. Speakers and pots date code 1976. This is a three channel, 10 input, with Automixer 4 button footswitch. Input and preamp section is solid state, output section is 200 Watts @ 2 ohm output through a matched Quad set of GE 6550B power tubes. Set tested out at 63 across all tubes. Caps have been changed in the output section as well as the 2 350VDC output caps. All original parts replaced will be included. Matching 4 X 12 2 ohm Speaker cab has CTS speakers date coded to 1976. A few, and I mean a few small scrapes on the tolex. The corners on the plastic vent on the head have cracked, but I will include the pieces. This amp is in perfect working condition and L O U D as hell. This was big in the stadium rock days. Footswitch is original. Between the 10 inputs and the Automixer footswitch, you get routing options that can combine the three channels in so many different ways. This is big and heavy. Local pickup only.

OK, needless to say, there's a puddle of drool now forming on my keyboard. Also take into account, I just had our income taxes done, and I'm entitled to a healthy return this year.

It's at this point that a bubble of air goes through my brain. The bubble decides "screw it... let's have some fun!". I send him a redonkulously lowball offer. I mean... for what it is... low. I'm not even going to mention what I offered for fear of anyone choking to death if they happen to be reading this while eating. Anyway, fire off the offer, log off, and then begin to wonder what kind of answer, counter-offer, or obscenities I should expect.

The next morning, I was struck by the proverbial thunderbolt when I saw the amp in my cart. That, along with a message from the seller, "When can you come pick it up?".

So yeah... now I have to rearrange my studio. Needless to say, when I told the missus of my mis-adventure, she smirked, and asked, "so when are you building the new wing?". God bless her little heart.

Moral of the story; don't make an offer, unless you're really really serious. Like I wasn't. But sorta was. Maybe. I think. Or is it, don't be afraid that you'll offend someone with a lowball offer, because they might just take it anyway?

I don't know anymore.

[Mark Hammer]

A hearty congratulations, Dino.  Will never beat my $30 tweed Bassman, but likely comes close.
That said, will you have to sell the Vette to keep this beast in tubes?  I only see 4 power tubes, so what kind does it use?  I'm guessing a KT variety.

The Korg unit is well made.  I'll be posting gutshots over time as I explore it, including the internals of the switching system as well as how they implement the "stereo" output.  For now, here a couple of pics of the external loop module the guy included. As you can see, it appears to provide a buffered in and out.  The modules may be plastic, but have an internal metal shielding shell that provides all the shielding you need.

[digi2t]

Nope, nowhere near your Bassman scoop. That one was one for the ages, for sure.

The Peavey is solid state preamp, tube power section. Quad 6550's.

I'm really interested in the octave as well, but I'm also wondering about the compressor. I wonder if it's something original, or a derivative of something else.

[Mark Hammer]

The compressor uses an LM13600, a 4558, a trio of 2SC2785 NPN bipolars, and has a 22k trimmer.  The "Attack" control is 150k, the Compression control is 500k, and the volume control is 100k.  Very near two of the transistors are a silicon resistor and 1Meg resistor.  Sounds pretty familiar, doesn't it?

The distortion uses some Harris SIP that is presumably a dual op-amp, plus a pair of 2SC2785s and a K30A FET, and a couple of diodes.  My guess is a pretty plain vanilla circuit but there are a LOT more passive components than one would expect for any sort Distortion+ derivative.  My guess is that it is trying to cop a DS-1 thing.

[Mark Hammer]

Looking at the phaser, there is a lot going on in there.  Haven't tried it out yet, but now I'm really looking forward to it.

Semi count is a lot bigger than the typical 4-stager.  EIGHT dual op-amps: five 4558s, two 4560s, and a 358.  Add to that a 4069 hex invertor, a 4016 quad CMOS switch, three trimmers, one transistor whose number I can't make out, and a 2SC1583 NPN matched pair.  Not any FETs in there.  Quite possible the 4069 is used as the control element, which would mean it can't be more than 6 swept stages.  There could be additional fixed stages, but I can't tell by visuals.  Needless to say, the board is pretty packed.  I'll post pics tomorrow.

[Mark Hammer]

Last but not least is the Octave V.  OY!!!

Four trimmers and two LM13700s.  Four 9-pin SIPs, only one of which I can see the part number of (NJM4558).  The other three are so tightly packed around with passive components that it is impossible to see what they are.  Not even a chance in hell of bending a few vertical resistors and caps out of the way to see, because nothing has enough space to bend.

But here's the real party spoiler.  There are two gooped modules: one with 7 pins, and the other with 15 pins, the latter running the entire length of the board.  The epoxy is thin enough to see what kind of things it contains but not thin enough to see what they are.  The smaller module has 3 surface-mount chips, an 8-pin, a 14-pin and a 16-pin.  The larger one is double-sided, with a pair of 8-pin dips on one side and a second pair on the other.  While the modules may be double-sided, the main PCB is not, which means there are all sorts of flying leads straddling all over the board to connect places that can't reach each other any other way.

Sadly, unless one has a few of these units available to sacrifice, I'm afraid it is not going to give up its secrets.  Dang.  And I was so looking forward to dissecting it and having it turn into a Dead End FX board. 

[digi2t]

Just... woah....



Going to keep my eyes peeled for one of these.

[Mark Hammer]

Turns out the compressor is pretty much a Korg CMP-1, but with the fast/slow switch replaced with a variable control.  Also turns out I could have saved myself some time and energy by looking here first: https://synthbrigade.altervista.org/korg-pme-40x/

[digi2t]

I see there's a 70 page service manual that was written for the PME-40X, apparently including all of the modules. I'm looking for a pdf version.

[digi2t]

I decided to pony up for a service manual. We'll see what we can gleen from it when it gets here.

[Mark Hammer]

A tip of the hat in your direction, sir.

[digi2t]

Update...

I contacted JAM Industries, who are the Canadian Korg distributors and service center. They also happen to be about 20 minutes down the road from me. They sent me an 8 page service manual for the base unit. While kind, not really useful.

According to stereomanuals, there is a service manual for the entire line, which according to the site totals approximately 70 pages. This is the one I decided to spring for.



I replied to JAM, I thanking them for what they sent, and also asked if there wasn't a more extensive manual that also covered all the pedals. I immediately (I mean, within seconds) received a reply "that doesn't exist". Of course, this isn't the first time that I've received non-help from JAM. They are actually pretty notorious for being non-helpful. Especially their so called "service department", which has gone beyond the call of duty in trying to convince me that a particular unit is not repairable, and I should just trash it and by a new one. Now I'm very curious to see what stereomanuals will be sending me. If indeed it is a complete service manual, as advertised, then it would further entrench my belief that JAM are just a bunch of @#$%ers.

Stay tuned...

[Strategy]

Watching this with keen interest. I've always wondered if the Korg pedal circuits have any similarities / relationships to their synth technology of the period. (I'm an original Korg MS-20 owner, huge fan of the brand.)

Of course, Dino knows firsthand my penchant for obscure 80s MIJ pedal designs (Holmes Spectrum!!? file under "what the...?!?" but still a favorite build)

My most recent acquisition along these lines is a MIJ Applause branded pedal called SUPER DISTORTION. Internet apocrypha calls it a direct OEM rebrand of a Boss DS-1 but the guy I bought it from said he started to trace the circuit at one point and noted variations. It sounds amazing and does not sound verbatim like a DS-1 to me either. From a $30 box of dismantled, parted-out, but largely salvagable DOD and Ibanez pedals I bought off a guy on Craigslist.

- Strategy

[digi2t]

Well... things are not boding well where the OCT-V is concerned.

Besides the fact that I still have not been able to get my hands on the service manual (don't ask, long story), I did get a look at a picture of the service manual cover. Unfortunately, out of the 12 modules covered, the octave module is not amoung them. I guess unless we find one to sacrifice to the cause, it's going to remain an enigma.

[stonerbox]

First off congrats Dino!

I'll type in something like "Traynor YGL-3", or "rare fuzz"....

That amp has such warmth and those ghost notes are super heavy (2:37)! Never heard of it before until today.

https://www.youtube.com/watch?v=07p8nTIRYH4

[wavley]

Does yours have crosstalk between the channels?  I'm working on one for a dude and I feel like it's completely normal for this amp to bleed the channels into each other a bit.  I recently rebuilt the power amp/power supply and replaced all the electrolytics in the whole amp.

How's tricks otherwise?  I've been staying away because I'm busy at the shop and resisting the temptation to build more stuff and mess with my rig so I can actually concentrate on making some records.

[fowl]

...my $30 tweed Bassman...

(record needle scratch noise)

Wait...what?  You wanna DOUBLE your money?

[digi2t]

Does yours have crosstalk between the channels?  I'm working on one for a dude and I feel like it's completely normal for this amp to bleed the channels into each other a bit.  I recently rebuilt the power amp/power supply and replaced all the electrolytics in the whole amp.

How's tricks otherwise?  I've been staying away because I'm busy at the shop and resisting the temptation to build more stuff and mess with my rig so I can actually concentrate on making some records.

Yup, there is a bit of crosstalk. It's exemplified by how the tone changes when you manipulate the offline volumes. I recapped the preamp section, and it didn't really affect that aspect of it. It might be the reason for the great overtones that stonerbox mentions, which in this case, is a good thing.

Not to totally derail this thread, I'm still on the lookout for an Octave V, so if anyone spots one for sale, please let me know.

[wavley]

Thanks for confirming that for me, I agree, it's part of the sound of this beast.

Ironically, I've done up two YGL-3s lately, one was for my old band mate and the other was for the dude that owns this Roadmaster!  He's got your guitar rig, want me to beat him up and take it for you?