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View Full Version : History of MXR Dyna-Comp pedals please


jbert
05-30-2008, 12:03 AM
Could someone explain to me what the difference is between MXR Dyna-Comp pedals from the 70's (script logo) and so on up til now. that is, if there is indeed a difference. thanks much.

mooawk
05-30-2008, 04:05 AM
The ones from the 70's can be modded for true bypass and they have better quality jacks. I'm sure there are other differences that others will chime in.

BurstWurst
08-05-2008, 11:41 AM
My MXR (script logo) Dynacomp has been doing an excellent job of holding my control room door propped open for 5 years now. ;-)

BMF Effects
08-05-2008, 12:56 PM
Transistors and transistor gains can vary. Older units can have carbon comp resistors (mine does). Capacitor material may vary. IC form factor changed. The 1977 factory schematic and layout papers I have match the early script unit I have but I've never played a '77 that sounds like mine. I don't *think* the general design has changed much (if at all) over the years but I also haven't seen any schematics for recent units. Dynacomps are one of the few pedals I'll give into mojo mysticism on. I've played a bunch and for whatever reason the one I have sounds very good while others have left me unimpressed.

BMF Effects
08-05-2008, 12:57 PM
My MXR (script logo) Dynacomp has been doing an excellent job of holding my control room door propped open for 5 years now. ;-)

When you're ready to close the door, shoot me an email. :AOK

MaxBoogie
08-05-2008, 01:33 PM
Also, early ones had no LED to indicate it was on... I still have one of those. :D

EBGB
08-05-2008, 03:44 PM
I have a block logo vintage one and love it
My tech advised against making it true bypass (or adding a light)
Compared to the new one with the light (maybe 8 years ago) there was no contest-- the vintage one was serviced at some point and sounds fantastic

rollo greb
08-05-2008, 05:45 PM
I'm waiting on a vintage block logo Dynacomp, and I've played others and I totally agree about the mojo thing. I plan on true bypassing it because I'll be using a couple germanium pedals after it. However I wouldn't add an LED, or do anything that involves drilling holes in the enclosure.

kenoflife
08-05-2008, 10:38 PM
I have a vintage block logo Dynacomp sitting in my basement- just slightly shabby looking and the foam inside is falling apart a little - anyone can say what its value would be?, because I really don't need it....

zachman
08-06-2008, 03:55 AM
MXR Dyna Comp Trivia
1972-1974 Script Logo "BUD" (Logo & pedal name in Script - light Aluminum - plate stamped "BUD" inside - Labeled Circuit Board)
1974-1977 Script Logo (Logo, pedal name & engraving in Script - Heavy Zinc - plate stamped "MXR INNOVATIONS" inside - Labeled Circuit Board)
1977-1979 Block Logo / Script Backs (Transition Pedals) (Logo & pedal name in Block engraving in Script - Zinc - plate stamped "MXR INNOVATIONS" inside)
Company shut up shop in 84 and the rights were sold to Jim Dunlop.
In the course of adding an led to the design, also changed other elements. The script and early Block logo boards use the Ross chip, but that also eventually changed.

Do you remember who did the actual circuit design for each MXR effect....how about the Dyna Comp?

That's shared between Richard and me; I'd say its more Richard's than mine. But its real close to my heart; I love that little box. the Dynacomp was so much fun. i really loved compressors; and for an analog engineer making compressors, a voltage controlled amplifier that really responds the way you want is a tough thing to find. They're all real noisy or or they've got some problem.....

.....we used what is called the 3080, an operational transconductance amplifier, and developed the Dynacomp around it. It didn't have the best signal-to-noise ratio, but it had a really nice attack characteristic, and I remember that Richard (Neatrou) and I experimented with just what the attack characteristic should be so it really gives you a good edge to a string pluck, and we had a real good time with it. I think if you ask Richard which box he feels closest to, he would say Dynacomp, and I would too.

Keith Barr, president and co-founder of MXR, speaking there (analog man's book). Richard Neatrou was one of MXR's first techs/engineers, working for keith before, in the company that evolved into MXR.

strings2wood
08-06-2008, 04:06 AM
MXR Dyna Comp Trivia
1972-1974 Script Logo "BUD" (Logo & pedal name in Script - light Aluminum - plate stamped "BUD" inside - Labeled Circuit Board)
1974-1977 Script Logo (Logo, pedal name & engraving in Script - Heavy Zinc - plate stamped "MXR INNOVATIONS" inside - Labeled Circuit Board)
1977-1979 Block Logo / Script Backs (Transition Pedals) (Logo & pedal name in Block engraving in Script - Zinc - plate stamped "MXR INNOVATIONS" inside)
Company shut up shop in 84 and the rights were sold to Jim Dunlop.
In the course of adding an led to the design, also changed other elements. The script and early Block logo boards use the Ross chip, but that also eventually changed.

Do you remember who did the actual circuit design for each MXR effect....how about the Dyna Comp?

That's shared between Richard and me; I'd say its more Richard's than mine. But its real close to my heart; I love that little box. the Dynacomp was so much fun. i really loved compressors; and for an analog engineer making compressors, a voltage controlled amplifier that really responds the way you want is a tough thing to find. They're all real noisy or or they've got some problem.....

.....we used what is called the 3080, an operational transconductance amplifier, and developed the Dynacomp around it. It didn't have the best signal-to-noise ratio, but it had a really nice attack characteristic, and I remember that Richard (Neatrou) and I experimented with just what the attack characteristic should be so it really gives you a good edge to a string pluck, and we had a real good time with it. I think if you ask Richard which box he feels closest to, he would say Dynacomp, and I would too.

Keith Barr, president and co-founder of MXR, speaking there (analog man's book). Richard Neatrou was one of MXR's first techs/engineers, working for keith before, in the company that evolved into MXR.

Great Post!!!!!:D

I love it when a Gear Pager goes the extra yard to be so helpful and informative.

wingwalker
08-06-2008, 04:10 AM
I agree, very cool!

Thanks for that.

alberob
08-06-2008, 04:11 AM
I still consider my early 70's MXR script logo Dynacomp essential mojo in my set up.It has never left my pedal board for over 35 years.Others have come and gone!:JAM

jstone
08-06-2008, 04:43 AM
As far as I know does the new dynacomps not use the Harris CA3080 IC that it was originally designed around.
Also different transistors are used now compared to the old ones.
The noise level can be improved by changing the transistors. I prefer the 2N5088 over the original script logo 2SC1849 as they are quieter.

The Ross compressor is an improved version of the DynaComp and has added filtering to battle the noise.

I guess most popular guitar compressors today are built around the DynaComp in one way or another.
The script logo MXR DynaComp is probably also one of my favorite pedals of all time.

BBHendrixon
08-06-2008, 06:16 AM
How long does a good battery last in these?

jstone
08-06-2008, 06:24 AM
How long does a good battery last in these?

Actually sometimes a flat battery sounds better :) It changes the attack a little or something like that.
But honestly I don''t remember I use PSU

rollo greb
08-06-2008, 07:47 AM
I have a vintage block logo Dynacomp sitting in my basement- just slightly shabby looking and the foam inside is falling apart a little - anyone can say what its value would be?, because I really don't need it....

I paid $100 for mine, in pretty much the condition you describe. It's the script ones that have a lot of value, probably due to legend more than any real difference in sound.