Help! Replacement Alembic style Q filter for an Aria 850 RS

Pickups, wiring schemes, switch techniques and onboard active electronics for guitars and basses
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mooger
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Post by mooger »

Hullo.
The short version is -
Does anyone know how I can replace an Alembic style active Q filter board which some previous owner took from the 1980 Aria Pro II 850 Rev Sound I now own?
The longer version is -
I have a sad tale of axe murder to tell, and I hope that one of those technical minds out there can help me towards a happy ending. Please bare with me. I write too much.
This is my problem. A couple of years ago, I decided it was about time I bought myself an electric guitar. After much looking, I fell in love with a 1980 Aria Pro II 850 Rev Sound. Well, who wouldn't?
So I “won” the Fleabay auction and toddled off to collect my prize. I got it for what I thought was a fantastic price, indeed the guy didn't really want to sell it to me for so little, but an auction is an auction. It played wonderfully, the neck, the ebony fretboard, the action, all utterly superb. It made me sound less average than I am. The electronics seemed a little meh, but hey.
More recently, my subsequent admiration of Matsumoku built guitars lead me to buy a couple more, though none as grand as the RS 850. There were a few pots and switches on various guitars that needed attention, so I turned my mind to fixing the electronic faults with help from someone who knows one end of a soldering iron from another. I decided that it was about time to sort out the Aria.
I knew that it had been modified, the extra mini-switch that had been drilled in was a give away.
In my ignorance, I had no idea of what a bad, bad job someone had done to it.
Now is a good time to copy paste the details I got from the Matsumoku site slick:

Aria Pro II 850 Rev Sound

Ash body, walnut stripes. Maple/walnut transmit neck. Heelless cutaway. 650mm scale. Ebony fingerboard. 24 fret. Two RSP-I single coil main pickups, slave pickup. (Humbucking)
RS circuit type 1: Master volume control, two active tone controls, two Q selector switches (3 position) and pickup selector switch.
Super tunable bridge, quick hook tailpiece, individual die cast machine heads.


Basically, it was Aria's attempt at something Alembic. The styling, the active pickups with Q filter control, the fact (or fiction) that Alembic sent Aria pickups and electronics when they were developing the series (though I have read that this happened just for the active basses, the likes of the SB-1000).
When Mick (the chap who is helping me with the electronics) took a look at the contents of Aria's cavity, he swore a lot. The wiring was awful, wires twisted together with a bit of tape instead of solder. Bare wire ends just left hanging. The x2 three position Q filter switches had been replaced with two position switches. They just seem to cut the tone frequency, or volume, or both. The third switch had been added to provide battery power (stereo jack option? Nah, lets drill a hole instead) and is a three position, even though it only needed to be two. Amateurish is not the word as I'm doing a disservice to amateurs. A retarded baboon could have done a better job.
Most disturbingly, someone had liberated the circuit board and done a bodge job replacing it with, well, I don't know what. A small black box with a few wires badly attached, rather than the relatively large enclosed PCB with the professional looking wiring loom attached. I've found a picture of what the innards of an RS 850 should look like, and it isn't what I have. (See pictures below)
So, I have a guitar that doesn't do the cool wah-like Q filtering, cos someone's nicked the black box. To add insult, after a while of wondering why the throw on the volume and tone pots didn't seem to do much, I discovered that they had used 250k pots for active pickups, which require 25k pots. With the impedance being out by a factor of x10, that at least explains why the potentiometers don't seem to do much. They act more like a switch than a pot, all the action taking place in the last 10% of the throw.
Anyone still with me?
So. I have a problem to which I have no answer. I suppose the first question should be, does anyone know of a way to get the whole active Q filter thing going on again? There's a nice example or two on You Tube of how the RS 850 should sound. is probably the best demo as it's played clean, but alas, I don't speak French.
A helpful RS 850 owner on Gearslutz suggested “The other thought might be to go over to "Freestompboxes.org" and see if anyone there has a schematic for the Alembic preamp and whether they might be willing to help you build the project?” Good idea, I thought. Though slightly scary.
I've been researching mod boards, but I can't find anything that might do similar. I'm seriously thinking about installing an active EQ pre-amp from Guitar Fetish, as, well, it's not nothing. http://www.guitarfetish.com/Onboard-Pre ... p_571.html for the f28 gain/mid/high version, or http://www.guitarfetish.com/Guitar-Prea ... p_411.html for the f29 gain/bass/mid/high version. I'd rather the latter obviously, but my guitar takes three pots, not four.
I wondered if I could mod the mod board by placing two controls on to one potentiometer, either by a push pull pot, a stacked pot or a mini-switch somehow. I don't have the knowledge to know if this is do-able, and when I asked GFS if it could be done, my reply was basically “Sorry, I don't understand. Ask a local guitar tech.” To which my answer was something like “Really? You don't know. Honestly?” I've asked a local guitar tech as it goes, but as he doesn't work for the company who makes the boards, has no knowledge of them and is busy being a general all round luthier, he didn't know. To be fair, I did give the guy at GFS too much detail (you don't say), and I think I may have confused him with words of three syllables or more. I've asked again using simpler language in the hope of a more useful reply.
Does anyone know if I could do the whole two controls on one pot thing with the f29 board? Surely a stacked knob would do it, though I'd prefer a push pull or a switch to keep it looking fairly original.
Failing all that, I don't suppose that anyone out there has an Aria 850 RS with a snapped neck, because if you do, I know someone who wants to buy the internal filter board off of you.
So, thank you for reading all of those words. I've written way to much as it is. All I have left to say is HELP ME (please, thank you)
In hope.
Matt
Attachments
How an 850 RS should look
How an 850 RS should look
The wiring in my 850 RS. (I've replaced the middle switch with a 2 position switch)
The wiring in my 850 RS. (I've replaced the middle switch with a 2 position switch)

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Jarno
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Post by Jarno »

Well, I would be very interested in seeing the original schematics, but someone has made a "alembic-like" filterpreamp with a perf layout. So you could DIY something that at least works the same.
"It crackles....., but that's ok"

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mooger
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Post by mooger »

Hi Jarno.
I'd be interested in seeing the original schematics too. Try as I might, I'm not having much luck. Rare guitar. I'm going to write to Aria and Alembic today, see if they can be of any help.
I've found this http://www.ebay.co.uk/itm/331142646057? ... EBIDX%3AIT which may or may not be exactly what I'm looking for.
I've asked the vendor, but it's not an everyday question.
New 3rd party Alembic pre amp and filters on e-bay. Could this be the answer?
New 3rd party Alembic pre amp and filters on e-bay. Could this be the answer?
It's the only 3rd party Alembic board I've found, and it seems to do what I'm wanting.
My other two brilliant ideas are to install one of the following, if it were feasable.
http://www.madbeanpedals.com/projects/K ... teShop.pdf
This is a Systech Harmonic Energiser clone pedal board. It seems to do not dissimilar to what I want it to do. It uses a notch filter instead of a LPF so it may be a little more, er, bitey, but it does the stuck wah filter pass thing nicely enough. Controls are bandwidth (Q, yey), frequency and gain. And it's very Zappa, as was Alembic I guess.
The other idea was to buy a Moog MiniFooger Drive, rip out the PCB and stitch it in to my guitar.
http://www.premierguitar.com/articles/2 ... iew?page=4
I've written to Moog to see if this may be doable. Again, it's similar to the original RS sound, LPF with gain, ouput, filter and tone pots and switches for peak and drive. No real Q control though, it may be too big, and it may be daft idea. I'm a Moog lover, so this idea appeals loads... I dunno. Here's a pic of the PCB.
Moog MF Drive PCB
Moog MF Drive PCB
moog4.jpg (27.92 KiB) Viewed 1914 times
I began researching how to build my own Moog style ladder filter, (again, you can get a PCB for it) but then I decided I may be over-thinking.

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HENK
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Post by HENK »

Google:
state-variable-filter for bass/guitar
(Pictures). :idea:

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