Moog Music Forum

One for Moog museum maybe?

http://www.ebay.com/itm/Keith-Emersons- ... 1230451647

Or Minimoog D for parts maybe ?

$8K for that ? No thanks. I already own a Mini in way much better condition than this butchered one. Keith Emerson or not.
If it was at least looking like this, it could be interesting maybe ?



By the way, this exact same item (the Keith Emerson one) was sold on eBay, by another seller in UK, on Feb 03, 2012 for $7012.09 with 4 bids.
So, presumably, the winning bidder is looking to make a minimum of $1K profit in turn by reselling it on eBay too.

There are a couple of pics of that unit from the GX-1 era but I can't find them online. It was to the left of his C3.

edite: oh wait they're amongst the pics in the auction.

This is what the seller has written to me after I had asked about the electronic modification:

"The Minimoog has some modifications that were done to it for Keith but they don’t seem to be connected and I have not been able to work out what they are for! On the keyboard ‘bender’ panel there are 2 red LEDs and a small toggle switch linked to a ribbon cable. Obviously this was for something that Keith needed on stage but I haven’t been able to work out what. The Electronics section has the ‘mains’ supplied via a DIN style jackplug and there appears to be a balanced output socket added.
All the ‘normal’ MiniMoog bits work as they should and I have just done a complete calibration on it. Note that this has the early ‘much much
richer’ sounding Oscillators rather than the later clinical ones!"

I'd like so much to see my very late "D" one day compared to a very old one to know definitively what about that "fat oscillators" on the early models.

Often, when talking about early Minimoog D oscillators, I suspect that "fat" means unstable and out of tune with each other...

Well, I'm gonna keep close to that thing and machine-gun my tech when he'll have one day two different ones on his table again.
He always claimed 'till now that there is definitivly NO difference.

megavoice wrote:Note that this has the early ‘much much richer’ sounding Oscillators rather than the later clinical ones!"

BS meter is PEGGED (at the seller not megavoice).

It's not the oscillators. It's the filters.

The early model D filter had all five transistor pairs matched, later ones only the top and bottom pair. I own one of the early RA Moog ones and have personally played two other early RA Moog model Ds (serial numero uno and #1009). Between these three they all had different oscillator boards - discrete, 3046-based, and ua726-based. THEY ALL SOUNDED THE SAME.

I have played a later model D with same oscillator board as mine - it sounded radically different. Because the middle three transistor pairs are not matched, this impacts the pole response of the filter IE the resonance will vary and the 24dB/oct slope will not be consistent.

Bob said that the oscillator boards all sound the same. He was correct.

It's not the oscillators. It's the filters.

Curious. My model D is serial 69XX and all the transistors in the ladder are matched (indicated by a small matching blue paint dot, applied by hand, on top of each).

Custom order? That is curious.

I got my info from schematics. They don't lie...

I have no info here indicating Moog ever matched the ladder filter top and bottom transistor pairs on a Minimoog. Perhaps confused with those later designs that used a CA3046 transistor array? Those models had the top and bottom ladder pairs matched using the CA3046 array.

The old schematics do indeed inicate that all transistors were matched in early Minis. And the later ones look to have only the bottom transistors matched, and the top four sets marked as selected but not matched. Have seen this on many Mini filter boards with purple marked bottom pair and blue market top four pairs. The later service manual has these parts listed as TIS97S. I can only guess the S suffix would indicate these are selected and are marked with blue. Moog indicated Matched pairs on schematics with an M in a circle next to the transistors to be matched. No indication what the selected range was on those other transistors, but they do seem to be at least selected. Colored dots indicating matched transistors was not used on my 1969 R.A.Moog. Not sure when this practice began, but probably during the later mass assembly of the Minimoog.
Old and new filter schematics and new parts list:


Here is an early serial#2498 with bottom pair matched (purple) and top four pairs selected. (blue)

All the Mini VCF boards here look the same as the one above with serial 40XX and 106XX, and were built years apart. The both sound very different and have since I got them. The 106XX in 1981 and the 40XX in 1984. My original 1974 purchased 37XX sounded different from my friends 40XX way back in 1975. The envelopes were different and Moog made some revision changes to the envelope between those dates. Moog did make many revision changes over the years. One would have to put the boards side by side to find the differences, and even if minor changes, there are differences between the years they were made.

The original R.A.Moog Mini also had different resistors on the filter/VCA board. They had a higher gain stage and were changed in later revisions. I have verified this with both schematics and photos of original boards.
Here are the differences:

So not only were the transistors all matched in the ladder, the gain for the VCA's was very different too. Whatever the reason, the Mini here with the newer uA726 sounds very different from the CA3046 oscillator board. Have swapped out the filter boards and did not notice much difference. Right now they are swapped and have been for the past year. The uA726 Mini did not get warmer or less stable. Those uA726 oscillators sound sharper/buzzier to me.
I can do some scope pics to compare both if anyone is really that interested.

My mistake. I didn't look carefully enough at my board #4 photograph. Indeed, the bottom ones in the ladder, and output buffer ones, are matched (purple paint) and the others are only "selected" (pale blue paint). Sorry for the confusion...
Incidentally, my #4 board looks identical to the partial photograph of yours in your post, CZ Rider. Down to the two transistors with red dots...

thealien666 wrote: Sorry for the confusion...

All a learning process. I'm always learning something new here. The purple and blue are close, almost have to look under the right light. Still have never seen any indication they used matched top and bottom pairs on a Mini though. That would be Micromoog, Taurus, Prodigy, Rogue and the like with that filter arrangement.

TIS97S is not a "selected" part. They were a product code from the manufacturer of some tighter spec. That convention has been used for decades and still continues today with ICs.

Back later with more info...

(never mind...)

MC, look at CZ Rider's post, you can clearly see that schematic with the circled M all the way up in the ladder, in his first pic comparison on the left from 1971...