Minimoog model D differences

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torinkrell
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Re: Minimoog model D differences

Post by torinkrell » Wed Jul 30, 2014 10:55 pm

CZ Rider - thanks for posting this intriguing analysis. I always wondered why the three Minimoogs that I have owned ( none concurrently ) sounded different. When I posted here before about this it was suggested that the differences I noticed with phase cancellation between oscillators with each Minimoog was due to power supply differences. In my experience the phase cancellation differences seem to be even more noticeable than the other differences. On my older (and current) 1973 Minimoog I was finally able to get superior phasing to my Pro One while the 1975 and especially the 1978 Minimoog fell short. The 1978 Mini would always have bright ripping sounds intrude on the warm phasing while my 1973 Mini phases in a very warm and creamy way. The ripping sounds of the 1978 Mini persisted even if I used tricks like lowering the level of one oscillator. CZ Rider - thanks again for your impressive and scientific research. I wonder what further study may reveal.
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noddyspuncture
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Re: Minimoog model D differences

Post by noddyspuncture » Sun Feb 22, 2015 7:41 pm

Hi Terry,

Are you absolutely certain that the Moog omission of the 10K resistor on the PNP side of the notes is incorrect..?

The reason I ask is that I am currently in the process of building this matching circuit as I need to match transistors for my 901a build... and I came across this page, where the Moog circuit is 'upgraded' etc...

here:-
http://www.musicfromouterspace.com/anal ... TCHER.html

I noticed that there the 10K resistor is also omitted on the PNP side...!

What do you reckon..?
Cheers,
Tom


CZ Rider wrote:
The Moog sheet on matching transistors seem to have an error. While the common schematic for the NPN is correct, the lesser used PNP circuit is missing the 10K resistor.
Here is a fixed schematic with pinouts of the common Mini/Modular transistors.
(Handy printout!)
Image

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CZ Rider
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Re: Minimoog model D differences

Post by CZ Rider » Sun Feb 22, 2015 9:39 pm

Probably not too important if matching the same batch of NPN's or matching a seperate batch of PNP's together. The difference I found was without the 10K resistor the readings are in a slightly different range than with the resistor installed. Only important I would guess if matching a PNP and NPN together. While not common, the Minimoog filter has a TIS92 NPN and TIS93 PNP that need to be matched per the schematics to within +/- 3 MV. In that case it would be best to build both the NPN and PNP sides of the transistor matching circuit the same. I do not recall any of the modular Moog circuits that required a PNP/NPN matched set.
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noddyspuncture
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Re: Minimoog model D differences

Post by noddyspuncture » Mon Feb 23, 2015 7:39 am

Thanks for the reply Terry,

The 901a controller has three sets of matched NPN and one set of matched PNP...! :)

Cheers,
Tom
CZ Rider wrote: I do not recall any of the modular Moog circuits that required a PNP/NPN matched set.

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latigid on
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Re: Minimoog model D differences

Post by latigid on » Mon Feb 23, 2015 11:45 am

Try also "Ian Fritz Transistor Matching" for a very simple circuit:

https://home.comcast.net/~ijfritz/MiscP ... mat001.pdf

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noddyspuncture
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Re: Minimoog model D differences

Post by noddyspuncture » Sun Mar 01, 2015 9:37 pm

Hi folks,

Now here's a thing... I just spent about four hours with my friend, Kevin's Minimoog, putting it all together so he can finally PLAY the thing. Jeeez...! Well, alI can say is "Phenomenal...!" I do know my Minimoog's quite well but his is just up by about 12 notches...!! I have never heard a mono-synth sound so good. Full, Creamy, Smooth, Bass-end just alive with movement. You can tune two oscillators as close as dammit... and usually end up with a static sound, but not here. Even the closest you can get to unison has animation and movement. Awesome, just awesome. I compared it to two of mine, which I have loved and treasured for decades... but it blew them both away. And it isn't even calibrated or in tune yet... I tried getting mine to sound identical to his - it was hard work. But whatever setting I made on Kev's sounded unbelievable. I have actually never felt like this... *Envy*...! I couldn't believe that a Minimoog could sound SO MUCH better than what I already knew.

Now, at the same time as Kevin bought his, I also bought my fourth from the same seller. I bought mine to sell... no even considering keeping it... after all, who needs four Minimoogs...!? But Kev told me to fire that up also and make the same comparisons. And I'm glad he did. It compared very well to his... having this something I can't really put my finger on, that his also has... and my others don't... :(

How can Minimoog's sound so different...? I think it is a mystical combination of parts and components coming together... it's hit and miss and each a one off. All hand built to a high standard... but there will be lucky unexplained accidents along the way.

All Minimoog's sound awesome... but apparently some just sound MORE awesome than others. And I'm glad the two we found two here take the biscuit... :) Looks like I'll be keeping this fourth Min after all.

Cheers,
Tom

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MC
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Re: Minimoog model D differences

Post by MC » Mon Mar 02, 2015 6:23 pm

Most Minimoogs use a filter circuit with unmatched transistor pairs (only top/bottom pairs are matched) which is a big reason why they sound different from unit to unit. The early RAMs/Musonics had all matched transistor pairs, the sound is more consistent from unit to unit. I own a RAM and the two other RAMs I have played sounded just like mine. It sounds great. Does it sound better? Purely subjective.

Also there were changes to the mixer circuit over the years. When the minimoog first came out, the engineering team realized they made an error that overdrove the filter but they hesitated to fix that "happy accident".
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noddyspuncture
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Re: Minimoog model D differences

Post by noddyspuncture » Mon Mar 02, 2015 8:37 pm

Cheers MC,

Yes, I know about the ladder-filter transistor matching... but I do think there is more going on here with these Mini's - mine and my friends.

I do consider myself extremely lucky in that I could actually easily compare five Minimoogs..! Most people manage to acquire one and that's the one they "know"... but when you hear that particular *one* - it just jumps out at you, it is THAT different and that is what happened to me yesterday.

I now have a dilemma in that I need to take stock and decide which of my Mini's to sell, as I really think four is too much. It's a nice dilemma to have though.... :D

Cheers,
Tom

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thealien666
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Re: Minimoog model D differences

Post by thealien666 » Mon Mar 02, 2015 8:52 pm

Easy, keep the one that sounds best to you, no ?
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Re: Minimoog model D differences

Post by Mr.ToR » Thu Jun 11, 2015 12:08 pm

Hi,

I have two Minimoogs.

R.A. Moog Minimoog Model D, Serial #1079
Image


MuSonics Minimoog Model D, Serial #1227
Image

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thealien666
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Re: Minimoog model D differences

Post by thealien666 » Mon Jun 15, 2015 12:36 pm

Mr.Tor, there is no Filter Scale adjustment potentiometer on both your filter printed circuits boards ? Image

I see the ones for A-440 Cal, 1st VCA Balance, 2nd VCA Balance, Filter Range, Filter Regen Cal, but no Filter Scale trimpot...?

Here's my filter board (serial 69xx): (the Scale trimpot is the one with a chrome finish)
Image
Moog Minimoog D (1975)
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MC
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Re: Minimoog model D differences

Post by MC » Mon Jun 15, 2015 2:28 pm

Early Minimoogs did not have a scale trimpot for the filter. My RAM unit doesn't have one.
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thealien666
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Re: Minimoog model D differences

Post by thealien666 » Mon Jun 15, 2015 2:46 pm

I didn't know that.

I knew that some boards around serial 18XX had a "vertical" trimpot instead of a flat one, but didn't think that the first ones had only a fixed resistor instead.
Thanks for the info MC ! :D

Oh, and thanks for your pics Mr.ToR ! 8)
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Re: Minimoog model D differences

Post by luckynerd » Tue Feb 23, 2016 8:27 pm

thealien666 wrote:Silly me. :oops:
I didn't realize that you were using the names of those ICs just as a means to differentiate between those oscillator boards... :roll: :mrgreen:

As for those caps, I don't know. I guess Kevin Lightner might be able to identify them, but unfortunately he doesn't seem to come here anymore... :(

One thing surprises me about them though, the markings on some of them state 50 volts maximum operating voltage when only a few volts actually run thru them (if I'm not mistaken)... Talk about overkill ! :shock: :D
The timing of this thread is quite ironic. 7/13/14 was the last day Kevin spent on earth. :oops:

All the filter board pics made me think quite fondly of the hours I spent replacing the caps and any resistors that looked suspect.
thealien666 wrote:Unless the comparison between Minis is done scientifically and rigorously, by using the exact same audio monitoring equipment, side-by-side simultaneously, any subjective reference of the type "it seemed brighter, or softer, warmer or colder", or any other qualifier of that type is pretty much meaningless. Especially when we all know how memory is something that is easily distorted with time.
Well said! *applause*
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