# Soul Preacher? Dynacomp? Advice?



## Greg Ellis

I'm looking to add a compressor to my board; it will be my first.

Mostly I'm looking to use it as a noticeable effect, like the beginning of Doobie's "Long Train Running", or BTO's "Let It Ride" or ZZ Top's "Fool for Your Stockings". Mostly with clean tones.

I've seen mixed reviews of the EHX Soul Preacher; lots of people seem to have noise problems with that, although nobody mentions HOW they're using the pedal when it gets noisy.

I've seen similar complaints about the MXR Dynacomp.

I'm not looking to spend a giant pile of cash; maybe $100 max., preferably less.

Any advice?

Besides the EHX and the MXR, are there any other reasonably-priced solutions I should be considering?


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## mhammer

ALL compressors are noisy. This is a logical extension of what they do. They crank the gain when things get quiet, so if there is the slightest hiss or hum in the input signal, when you stop playing the compressor will react to it as if it is the tail end of a note dying out that could _really_ use a lift.

There are limits to what mods and improvements to a compressor will do with respect to this problem. The real cure lies in a) not diming the compression, and b) feeding it an inherently clean and noise-free signal.

Unfortunately, because a lot of players don't quite understand the internal functioning of compressors, one hears a lot of complaints about such and such a model being "crap" because it produces noise when you stop. It's a bit like saying a Mack truck is crap because it doesn't stop immediately when you take your foot off the gas going downhill. The problem there is not with the truck.

That's not a criticism. Rather, much greater satisfaction will be obtained from just about any compressor if you know how they work, and play according to their rules. 

The Soul Preacher isn't a whole lot different than a Dynacomp or a Ross or the many commcercial variations on, and clones of, the Dynacomp and Ross (which are, themselves, near identical twins). The practical difference between the SP and MXR is that the SP provides 3 different recovery times. Recovery is pivotal in the feel and appropriate application of a compressor.

How? Feed a compressor a strong transient, and it immediately turns the gain down in response. But how quickly is the gain restored? If the gain is restored slowly, then notes held via finger vibrato will seem to linger a long time (i.e., the illusion of sustain). Unfortunately, if you pick another note very soon after the first, the gain is stick down so the "attack" of that second note is not heard very well. It's like a comedian trying to tell a second joke while the audience is still busting a gut over the first one. Obviously, unless they wait a bit, the second joke will fall flat. If the gain-recovery time is made shorter, then the illusion of sustain will not be as pronounced, but the unit will be "ready" to let quickly picked notes be heard clearly.

The effect of recovery-rate is not heard on its own. It is strongly dependent on how quickly you pick. So, optimal settings are longer recovery time for Paul Kossoff / Tom Scholz single-string note-holding, and short recovery times for chicken-pickin when you channel your inner Brad Paisley.

Some years back when Tim Larwill was getting Retro-Sonic off the ground, we used to have many chats about the design details. He was making a Ross clone, and I suggested adding a recovery-time switch, using a 3-way toggle for slow-medium-fast, and we agreed on the values. Eventually, he turned it into a rotary knob. When I asked why, he noted that while, just like myself, he couldn't see any value to more than 3 settings (and hearing differences between fast and medium can be tough), customers felt more comfortable having continuous control, so he yielded to consumer demand. The EHX pedal has 3 settings, and that's pretty much all you need.

Note that many companies making Dynacomp-inspired 3-knob compressors over the years (Including the Boss CS-2) have implemented a variable recovery time control, but called it "Attack". It IS, and remains, a gain-recovery-time adjustment, electronically, and has no discernible impact on the attack of a note in isolation. But because it has an impact on the attack of the next note, if it comes on fast enough, and because "Attack" sounds sexier than "Recovery", they continue to call it an Attack control.


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## mugtastic

^ great post!

now i know what the "attack" knob on my cs-2 is doing.


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## zurn

Indeed, thanks mhammer!


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## david henman

...janglebox?


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## Greg Ellis

david henman said:


> ...janglebox?


$179+ for the cheapest one, unless I'm missing something?


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## gearalley

1 vote for the Soul Preacher, althought I've owned a Dynacomp and it was was pretty good. Just a bit sensitive to control (I found)


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## mhammer

mugtastic said:


> now i know what the "attack" knob on my cs-2 is doing.


As well as why it doesn't seem to be doing much of _anything_, sometimes!


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## Greg Ellis

Dyna Comp seems to be missing that "recovery time" control. Is it hidden inside somewhere, or simply not available? You're stuck with whatever the manufacturer thought was best?

Edit - never mind, I see it now. If I want that control, I can buy the Super Comp for $10 more than the Dyna Comp.


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## mhammer

It's basically the difference between using a single fixed 150k resistor, or replacing it with a variable resistance. Smaller resistance = faster recovery, larger = slower. 150k = slow recovery. The CS-2 uses a 150k pot in series with a 10k resistor, so that resistance goes from 10k to 160k total. The Marshall "Edward" compressor does too. The Ibanez CP-9 uses a 100k pot + 24k. Other designs may not use the same system for extracting the signal envelope, but these, and all MXR/Ross variants do too.

There may be other differences, I suppose, but a Dynacomp can be easily modded to provide several different recovery times. I've done it on mine and the difference is audible.

Note that the Danelectro Surf & Turf compressor is actually a Dynacomp inside, so you can get your squeeze on inexpensively. (A number of Dano mini pedals are clones of designs that no longer have patent protection.)


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## Greg Ellis

I thought about the Danelectro. I have their Phaser already, and it's fine for what it is.

I've seen Surf & Turfs around for very cheap. Definitely worth considering.


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## hughesp

I had a dyna comp and found it too noisy at the time... it certainly wasn't a transparent pedal, but I personally like the colour that it adds to your tone. I feel like that is part of the charm of the dyna comp. You either like it or you don't - so make sure you try one out. I really loved the sound, but couldn't take the noise.

I recently picked up an older DOD FX80b for $30. These pop up used fairly often and aren't worth a whole lot, but I actually prefer mine over the dyna comp. Much less noise, and just seems to sound better to my ears... but everyone looks for something different in a compressor. 

If you want to really spend some good money, though, I hear Keeley's compressor is hard to beat, though I haven't had much experience with it.


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## mhammer

Looking at the components in the FX80B, it appears to be yet another variant on the Dynacomp. The input and output stages are an improvement over the Dynacomp. 








There are (at least) two versions of the FX80B, it would appear. The version shown in the photo has a "Release" control (recovery time) and uses a CA3080 chip, just like the Dynacomp and Ross (and so many others). You can see 8 transistors on the board, at least 2 of which are used for switching in the now-standard DOD circuit up in the right hand corner of the picture. Below, we have the schematic for another issue of the FX80B, which uses a CA3094 (a slightly better chip than the 3080), and a TL022 instead of the MC1458 (again, a bit of a step up), but more importantly replaces the release/recovery control with an actual "attack" (i.e., quickness of onset) control. There are also only 6 transistors on the board, 2 of which are for switching. Which issue is better, I don't know, but they do appear to be somewhat different in some audible ways.


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## Greg Ellis

I settled on an MXR Supercomp; seems like a good compromise - dynacomp plus a sensitivity control. 

I saw one pop up for a fair price, so why not?

I'll update once I get a chance to play around with it.


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## keto

dup post bug bites again!

I'm sorry I missed this thread first time around. I would have strongly recommended the Marshall Edward comp. Extremely tweakable high quality comp. Not sure what circuit it's based off (most, as referenced above, are based off a couple of old circuits) but I've had mine for years and never had an issue, and it does what a comp does and then some.


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## mhammer

The Edward is also essentially a Dynacomp, but has a few interesting tweaks.

First, it has the better input stage, like the FX80, and a better output stage.
Second, that improved output stage separates/isolates the audio output stage from the rectifier stage. JC Maillet has a mod to do this on a Dynacomp ( MXR "Dynacomp" /// Low Battery Sim and Hi-Fi Mods ), albeit in a different way, that essentially makes the best of a bad situation.
Third, it adds an additional stage which lets you adjust what portion of the spectrum the rectifier responds to most. In one direction, it is most sensitive to stuff in the bass/low-mids side, and rotated the other way, it responds more to upper mids.


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