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WIGGLING 'LITE' IN GUEST MODE

Some words about Mike Peake
MUFF WIGGLER Forum Index -> Buchla, EMS & Serge Goto page 1, 2  Next [all]
Author Some words about Mike Peake
ritchiedrums
I am posting this here because it is about my 208r.
If you feel this post should be somewhere else on here.... move it.

In a world where so many people are quick to Rant &
Post negativity everywhere.... I want to post something NICE!

August 2017 I purchased a used 208r here on Muffs.
Great guy & a very easy transaction.
The reverb was broken & a couple of other functions felt quirky.
This 208r was originally built by Peake,
so I got in touch with him.

Mike not only fixed the reverb & addressed my requests,
but he also added a couple of mods.
All at no charge to me.

This is a man who stands 200% behind his work. Guinness ftw!
ym2612
Mike is a class act! I bought a 158 board and panel from him to build myself, and he included rare parts and offered support on the build, to the point of offering to fix it himself when I was having trouble with troubleshooting. I ended up finding and fixing the problem myself (builder error), but the 158 sounds great!
Peake
Ritchie is being far too kind...my already literally disabling physical health has been extremely low for months and I got piled up with projects and took months to do his mods and calibration...Ritchie was regardless very understanding and generous. I still owe one more project from that batch to another extremely patient person. Thank you Ritchie, your being happy with the module is highly gratifying. Best wishes to you for a wonderful new year. Super shout-out to Dave Brown who showed me how to accomplish the mods and repair, speaking of amazing people. (The 208r had been damaged and some wiring replaced, causes unknown.) Thanks ym2612. I mean well even if I can't always pull it off.
djangosfire
I love reading positive posts... especially when I agree 100%!! Guinness ftw!

Cheers!!
J3RK
Agree! w00t

May all Mike's Vactrols misbehave within the appropriate margins!
Minimoog56
I concur with all the good vibes stated above. Great peeps.
chorus7
Likewise agreed... Mike you are a gentleman... amazingly talented and kind... we're not worthy
vgermuse
I'm jumping on board! Kudos well deserved Mike!
I've always cherished our transactions and interactions.
Mike rocks!
ritchiedrums
https://youtu.be/16ePoxozKEs
Peake
There's that tracking non-linearity I mentioned in the 3rd Octave. Cannot figure out how to get three accurate octaves out of a 208; it always goes out beneath the octave for which you trim. I've followed published calibration procedures and tried different things...
qu.one
hear hear... an invaluable MW member.
Ozz
Well done, Mike. This is a great community.
SlayerBadger! applause
folpon
Love this positive post. smile

And also love the reassurance that I'm not insane that my 208r can't quite track 3 octaves no matter what I do... :..(..
Peake
Yours too? The given tuning procedure is to set the front panel accessible trimpots to center then use the CO and MO Range trimpots on the rear to set V/Octave response...I'm going to use multiturn trimpots on any future builds for all of those. Won't make it track better but would be easier to dial in.

I wonder if the keyboard response trimpot should be set lower or higher than center before setting the MO and CO Range trimmers. Or if the HF linearity circuits are causing the problem and can be somehow tamed. I mod the MO and CO trims for these with 500K multiturns and you can indeed get them in the zone but at the expense of what's below it :(

Thanks everyone for the kind words.
papz
The 208s I build with the pA726 expo converter track on 5 octaves. A fine calibration needs subtle selection on test of R5 and R58 on board 6 and R14 and R44 on board 7.
Multiturn trimpots are not needed.
muncky
papz wrote:
The 208s I build with the pA726 expo converter track on 5 octaves. A fine calibration needs subtle selection on test of R5 and R58 on board 6 and R14 and R44 on board 7.
Multiturn trimpots are not needed.


Hey Papz - any chance you could give a bit more detail? I’ve built mine with UA726s, but intend to treat myself to a further calibration in the new year nanners
papz
In my latest build, calibrated for 1.2V/oct. :

Board 6
R58 : 390k
R5 : 91k

Board 7
R14 : 44k (68k added in parallel with 120k)
R44 : 150k
R45 : 100k trimpot

These values might not be ideal in another 208 or with another expo converter, why selection on test is needed for R58 and R44.
R5 and R14 values should be ok for 1.2V/oct. but not for 1V/oct. or 2V/oct.
It's a time consuming work : 5-10 minutes warm up time and calibration adjustment are needed for each resistor change.
muncky
Thanks Papz - will try it out and report back in the new year
folpon
Ok. I feel inspired now, thank you Papz. My third octave (i'm using ua726's with some custom resistor values already) is only maybe 10-15 cents flat of the others -- which felt playable to me. But this thread makes me think I ought to dig in just a hair more. we're not worthy
Peake
I used a jhulk uA726 replacement in the other 208r I built and it seemed to do better especially with the heat up. I will absolutely be using those again. Could the uA726 be a limiting issue?
papz
I built several 208s using µA726/uA726 (old and new) as well in the past and was able to calibrate proper tracking on about 5 octaves although I remember it was a bit more tricky, but maybe this was because these were my first builds.
5 octaves seems to be the µA726/uA726 limit in this circuit, the pA726 can go a little higher, in a build I even got almost 6 octaves.

I have no experience with jhulk's circuit so I won't comment about it.
Peake
It works perfectly, I'm sold on it. I've heard of people getting up to 5 octaves, how linearly though? Is this done through ignoring the HF linearity trimmers? Or over-doing their settings so the result is linear...I'm wondering if proper calibration is not object-oriented in terms of listening and trimming to the desired point but on the HF trims, to tune them to the desired response then to further out so the linearity in the octave(s) below is actually compensated. So many potential variations :(
papz
Well if it works perfectly, your calibration schedule might not be perfect then.
I calibrate the tracking on a 208 with a 218.
I first adjust the offset and range trimpots with a frequency counter and then I adjust the HF (and LF for the CO) tracking trimpots and the panel "(trim)" ones together, and change the aforementioned resistors if the HF trimpot is off range, using a Boss TU-2 chromatic tuner.
To me, proper calibration means all the notes played with the 218 are in tune with MO initial frequency C0 (32.7Hz) and CO initial frequency C1 (65.4Hz).
Peake
HF trims and front panel keyboard trims at the same time, interesting. I mod my builds so the HF trims actually do something (500K multiturn trimpots). If you have a written procedure with target pitch frequencies it would be highly appreciated if you'd share it with the community in the 208r build threads.
papz
I have no written procedure, I'm just sharing what I learned myself building and servicing 208s and other synths.
The target pitch frequencies are written on the panel. hihi

As far as I know, no calibration procedure or service manual exists for the 208.
I think to write a detailed one and share it on my website for the 208 PCBs I'll offer soon, but it's not a small job...
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