MXR DynaComp

This simple two knob compressor has attracted throngs of faithful followers. What sets the MXR apart from hundreds of other stompers is it's unique voice. It's really not that transparent or really that clean but, for some reason, it makes guitars comes alive. The Dynacomp isn't subtle and the strong squish it creates can be startling at first. Upon first plugging this in, you may have some reservation about the stranglehold it has on your tone but after a few adjustments this things can make your guitar come alive. We prefered leaving the DynaComp on at all time and scupting our overall tone around it but some players like using it for just one/off utilities. These duties include leads, clean chicken picking, or simple boosts. It works well in all these scenarios as long as you take the time to tweak your whole rig to taste.


Vintage vs Reissue

Info from punX Gear Site



Not a test review yet but something I came across recently I wanted to share
(a proper review coming soon)

I own a 1974 MXR Dyna Comp (script logo) which i've been using for the past 10,11 or 12 years. In between I owned a second one, which was an early 80's block logo model (NO 9V out, NO LED), it sounded 1:1 the same to my Script logo model. I recently purchased one of the latest MXR Dyna Comp models and the moment I plugged in I realised a serious volume drop – no matter the Volume setting. I hadn't even turned the SENS knob up. The Volume knob didn't even matched the input level I sent into the pedal when "off" - it was almost like my experience with the Boss OD-2 - the volume knob just didn't deliver line level. BAD!

Before I go further … I kept the signal path super simple: Stratocaster > MXR > Vox AC4

Ignoring the Volume issue, I played with the SENS knob and the pedal started pushing, popping and plucking notes heavily even on lowest settings. It just behaved like a "proper" compressor - all the charm that my vintage MXR has was gone with the new model.
Besides, where I can use my old MXR DC almost as an overdrive, the new one won't let me even push the pedal and tone that far.

So, I opened up the pedal in the hope I could help by changing the internal trim poti …. pah! the platine is screwd tight onto the enclosure, no quick way to access the trim pot (see images - save images for larger versions!).
After I managed to take the palatine off the enclosure I played with the trim pot and …. nada. No improvements on the volume and no improvements getting rid of that annoying heavy tone pumping.

I have no idea what MXR/Dunlop have done to the DC pedal but think this pedal is SO different when compared to my vintage model that I can’t understand why it has the same name.

MXR DC's from earlier years sound fantastic. But the most recent pedals do great compression in a general sense, but they are not what the vintage pedals sound like.
Basically MXR/Dunlop has taken from the DC pedal what used to be so unique about them.
Add to that how tone sucking they've become and you got a highly unnecessary pedal.

MXR Vintage Pedals- Block vs Script - (eBay User Review)

"I have fallen in love with a couple old MXR pedals and want to share what I have found in regards to circuit differences and dating. Disclaimer- This information is to be taken as advice- use your own judgement. I am glad to answer questions but you MUST provide your email address- Ebay will not let me respond to questions without a transaction. (idiots…. Ebay calls me a top 10000 reviewer but cancels any responses to Ebay members questions in regards to this guide…)

There are 3 versions I am grouping- Script, Block, Reissue. This guide is to help define the 2 vintage versions- Script and Block. Heres what Ive learned, and I have actually seen these differences-

  1. The Script versions are DIFFERENT than the Block- ALWAYS. Maybe not by much but there are differences on the circuit board- EVERY TIME. As to the question "do the early Block logo with minimal differences SOUND as good as the script?"- the answer is ambiguous. These pedals can sound different especially if someone has played around inside- which is VERY common. You really have to hear them side by side to make a good decision (which is of course often not the case). Bottom line is I wont make any judgement as to sound other than the Reissue pedals are NOT the same as the originals- any version.
  2. There are MANY versions of Block logo - the later version began, from what I can tell, before the Block logo got an LED at the end of its span, but I am not sure where to draw the line. Potentially when the small logo on the back changed from script to block. Are Block logos different? Yes, as always use good judgement. Early block logo pedals remain extremely close, if not identical to late run scripts.
  3. Date your pots! On each pot there will be 7 numbers. xxx77xx means they are from 1977. The first 3 are the manufacturer code!
  4. Check your BACKS! The MXR logo changed from script to block on the bottom back corner. This is "potentially" a line between good and better. Again, use your judgement.
  5. NEW DEVELOPMENT!!! After purchasing an EARLY 1974 script logo dynacomp I discovered that EVEN SCRIPT LOGOS HAVE DIFFERENT COMPONENTS. Side by side, different!!!! How different, I have no idea- but different YES! Jeeze, this just gets more convoluted! Im estimating pedals in 1974-1975 are different than 1975-77(maybe divided around the change from bud boxes?) BUT not as different as the 1st Block logo circuit change is from ALL THE REST. So I still say use your judgement, all scripts and many blocks will make you very happy! NOTE: I am thrilled to find that my new 1974 script dynacomp is in a bud box, and though pretty thrashed, absolutely PHENOMENAL. It is VERY different than my Block logo- though it looks like the internal pot was accessed on BOTH pedals so I may have to experiment on the Block logo… There are MANY, MANY visible differences on the circuit board BUT that could be the same component in another color as far as I know- AGAIN, use your own judgement.*
  6. Didn't want to forget the "Bud Box". - Its just an early enclosure and on the backplate, on the inside, YES IT WILL SAY "BUD". Collectors like these as they are typically the earliest incarnation of the pedals. Players like them because they are the grandaddy of mojo- the first pedals! Whether they sound different….probably no more relatively different than other versions can.

*Side note: according to the Analogman interview with one of the founders of MXR, the early Bud box variation in tone could be potentially the result of limited resources to buy components. Thus the manufacturer used whatever they could find/afford to build the pedals. Damn engineers, always ruining my MOJO! Its this inconsistency that may be part of the MXR magic!

Point of interest- A mint(and I mean the foam inside was PERFECT), Dyna Comp went for $485. (But I would pick my 1974 bud box beat to crud over it in a second- and I paid 125! Sonically I guarantee it doesn't sound any better so I saved $360! Just making a point :)

It also adds to the reasoning of the 3 contributors to the Dyna Comp tone- 1) which set of components PLUS 2) has the internal pot been adjusted PLUS 3)HOODOO VOODOO. It also supports the theory that all the pedals can have a little of their own magic and a Block can sound as good as a Script. But as always-USE YOUR JUDGEMENT. Yes you may be WAY happier with the tone you get from a Block logo… And it will save you at least 100!

TIP TO PLAYERS- Don't waste youre time on the mojo. Old MXR pedals, pre dunlop, sound great. Save money and buy the versions everyone isn't fighting over. If you are a tone LUNATIC and ALSO do a lot of recording (subtle mojo is worthless at live shows) then look into fine tuning. Otherwise, buy a pedal and play it! The only good thing about collectors is they will eventually die and rerelease the pedals back into the wild. And then people like us can buy them in mint condition 30 years from now.

ALSO- if you need ORIGINAL MXR back plates WITH a battery clip hole-they are sold here on EBAY! I have NO AFFILIATION with the seller- Ive just bought 3 from him and am VERY satisfied. search "store listings"- "mxr backs" (the listing should bring up MXR factory replacement backs) They are the original replacement plates from MXR!

Batteries VS AC power- Ive also come to the conclusion that I definitely PREFER the pedals powered with a BATTERY as opposed to ac power w/ adaptor. The constant power of the ac adaptor adds bass, slight roundness in the mids, and crisper highs- SO THIS IS DEFINITELY A PERSONAL PREFERENCE. There also seems to be a slight added distortion when the batterys have gotten some use(voltage drop) that I prefer. As always, could be psychoacoustics so USE YOUR JUDGEMENT!

True Bypass note- these pedals are OLD SCHOOL and will pass signal without power BUT THEY ARE NOT TRUE BYPASS. The pedal is still attached to the circuit board so it affects loading of the guitars pick ups….. ie TONE SUCK!

I got an email from an Ebayer asking about ac power instead of batteries. What I use is the one spot ac adaptor with a 9v battery connector they also sell. If you get a real MXR replacement back from the aforementioned, they have a small hole that allows the cable out (otherwise you would have to leave the bottom plate off or drill a hole in the case). The one potential problem with the one spot is it can get noisey. Rarely but true and Ive had it happen at the worst place possible - IN THE RECORDING STUDIO. But 95% of the time it will work- or at least it does for me. Best part- very inexpensive!

The bottom line is this is all potentially hoodoo voodoo! I have played many MXR pedals over the years ( yes, I was alive in the 70s! ) and own a script phase 45,1974 bud box and 1977 Block logo dyna comp, a bud box phase 90, and a 1979 block logo distortion plus. I love them all. The fact that you can get a script phase 45 for WAY less than a phase 90 is completely insane to me! I will also admit that I have bought into the MXR mojo. The dyna comp is absolutely unreal. Period. BUT if you don't want your tone smothered in MXR gravy, a Keeley would be way better! You can't shake the MXR mojo! I hope this guide at least helps you be sure you ARE getting what you want! And definitely DON'T believe the hype- there are better compressors, phasers, distortion pedals out there. Seriously. If I hadn't fallen for guitar in the 70s, I would probably prefer something better, but for now Im gassing* for MXR! (Note: 2 of 5 of my MXR pedals would be hard to resell- they look like CRAP, but they sound SOOOOO good! Don't live by looks, especially with these pedals! Plus my favorite one-the bud box dynacomp- is in the worst condition of all!)

So I finally got my 1974 phase 90 back and in perfect working order. One of the translucent board versions if that means anything. It sounds INCREDIBLE. Its like cream and butter slathered in mojo…. Ok really, it sounds wonderful. The Block logos are NOT the same pedal. Even the early ones. This pedal deserves all the hype. Compared to my script phase 45, its way warmer and creamier- yes two completely useless words in musical terms, but they are right on in this case. I love my 45 but there is a wierd thickness to the 90 that is just incredible! Its like a light distortion but perfect…….. My understanding/experience is that the block logos, in general, use a more effected signal- its stronger. Again, use your own judgement. (and don't think I prefer it over the phase 45! But its thick…..)

And next to come is the script phase 100 that looks like its lost a fight…. Fed Ex tried to deliver today… That should be a fun pedal! WAIT as Im typing this he is back! I gotta go! NICE!

For more and BETTER information about this and other effects check out Analogmans effect guide- I have NO AFFILIATION other than I own it and find it a GREAT reference tool! Bought it here on Ebay!

Note- ( I may have left some out- sorry to those whos pedals aren't represented! And I purposefully left out any pedal not in "bud box" size enclosure.)

MXR pedals nobody cares about, thus DON"T PAY HIGH FOR THEM regardless of script or block- Line Driver, Micro Amp, 6 band eq (don't believe em!)

MXR pedals EVERYONE cares about- script versions of: Dyna Comp, Phase 90 and 100, distortion plus

MXR pedals MANY people care about- Block dyna comp, script phase 45, block envelope follower(not sure if there is a script version)

*gassing- gear acquisition syndrome ie gas. Sometimes referred to as guitar acquisition syndrome."

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