MOOG MODEL D DAY!!!!!! with pics

[shipatsea]

Here is my new baby, complete with original manual, sound chart and sample sounds. The wood is perfect and even has some flame in spots. Cosmetically it is perfect! I even got an S-trigger dummy plug. I thought it was a 72 but turns out it is a 74. I have read hot debate about whether it is the early discrete osc board or the filter that makes the earlier ones sound different. Is it true that the later filter boards only had the top and bottom transistor pairs matched? I have heard that the earlier ones had all pairs matched and that was the key to the sound. I wonder if they were still all matched in 74.

I got a good deal on this but it needs a couple things. Osc 2 is out – missing a knob – bad output switch – key bushings need replacing

I have a knob and the key bushings on order. I have a replacement rocker switch on order (although it is black)

I will be sending all 4 boards into Kevin Lightner for a full restoration ($400 is a bargain!)

[MC]

I have read hot debate about whether it is the early discrete osc board or the filter that makes the earlier ones sound different.

They sound different because of the filter. All the oscillator boards sound the same.

Is it true that the later filter boards only had the top and bottom transistor pairs matched? I have heard that the earlier ones had all pairs matched and that was the key to the sound. I wonder if they were still all matched in 74.

Yes laster filter boards only had top and bottom transistor pairs matches. I have schematics for early units and they confirm that all pairs were matched. My schematics for late units show only top and bottom pairs were matched.

I have personally played three early units (serial 1001 numero uno, 1009, and my 1053). All had different oscillator boards, yet they sounded alike. Played two late model Ds with same oscillator board as mine - sounded radically different.

The reason late units had different sound from unit to unit was the top/bottom pairs were the only ones matched. With unmatched pairs in the middle three, the pole position of the filter response wasn't consistent. It is more noticeable as you turn up the filter emphasis.

I don't know the exact date they changed the matching. Matching transistors is a labor intensive job, this was one place they could cut corners.

The Voyager filter has all matched pairs and it sounds really close to my unit.

[shipatsea]

MC,

do you know how I would tell by looking at the board if they are matched? Any special markings?

I am sending all 4 boards in for an overhaul by the Lightners. Do you know if they match transistors to replace the mismatched ones in the filter section?

[MC]

They're not marked.

Kevin may be the better one to answer that.

[Unfiltered]

you shouldn't have opened it up, you probably voided the warranty. you might want to call Norlin and to make sure. Not sure if you guys heard, but this new band called Journey is playing the Superdome this weekend, you dig?

[CZ Rider]

do you know how I would tell by looking at the board if they are matched? Any special markings?

Seems they marked the matched pairs with colored paint dabs. The newer schematics I have indicate only the bottom pair were matched, indicated by the circled "M".


This would seem correct as the bottom pair on my 108XX Mini has the bottom transistors with violet markings and the top four pairs marked in blue. I would guess the blue marked ones were a least screened and selected.

From the photos you posted, it looks like the same markings, the bottom two with violet paint dabs and the top ones with blue markings.
Cropped and brightened photo:

I could see where if the transistors in the ladder were really mis-matched, it would throw the filter poles off. But it would seem Moog used selected but not perfectly matches transistors in the top pairs. Still it would be interesting to swap in matched sets to see if there is an audiable difference. I have my doubts though that it will sound like an RA Mini with the old oscillator board, but could be an improvement? I have a bag of new TIS97's from Mouser.

[MC]

This is the schematic for the early units (too big for embedding)

http://www.ka-electronics.com/Images/Mi ... Filter.JPG

As you can see, all the pairs are matched.

None of the pairs on my RAMoog unit are marked. That practice must have been later.

[shipatsea]

CZ Rider,

Thanks! That's interesting. What year is yours from? your boards look cleaner than mine. I'm sure once I get mine back from Kevin they will look awesome.

[CZ Rider]

What year is yours from?

I think that one was built in 1978? Those had the last revision osc board and the serrated wheels. The wood cabinets were different, a little thicker and a mud finish on the wood. The ones made in the early to mid 70's like yours really had a nicer wood finish. I picked up that one as my second Minimoog back in 1982, so I have had it for over 28 years. Still looks clean all these years later.

Just passed on a MuSonics mini the other day ser 18XX. Didn't have the first revision oscillator board. But the wood looked great, and it had the clear wheels with metal panel!

[shipatsea]

that sure is purty! I like the dark finish on the wood of the later ones.