# What is like a dynacomp but better?



## achar073 (Jan 1, 2021)

I have a modern block logo dynacomp. I like the super squashy compression thing it does but I don't love the attack. It can almost sound like there's a "popping" noise when you play a note sometimes...? It's something I can live with to some extent but I feel like there's probably a compressor out there that does the "squash" thing but has a smoother attack.

I know about the script reissue dynacomp and it sounds slightly better in demos but is it worth the extra dough? L&M wants $220 bucks which puts it in the same price range as many alternatives, some of which might be better. I looked at demos of the Maxon CP-101 and it sounds good but it is a hard pedal to find and can't try it out in person.


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## Granny Gremlin (Jun 3, 2016)

modded dynacomps:

Ross Compressor was the first back inna day (mostly better power supply/filtering)
Boss CS-2 added a buffer and "attack" control (actually release; misnamed)
Way Huge Saffrom Squeeze
Analogman CompROSSor
Keeley Compressor (added a bunch of tweaks over the years but still based on a Dynacomp at the core)
Janglebox (similarly now has like 6 knobs)

If you're handy, Aion Electronics makes a DIY kit /pcb. You can build it as A Dynacomp, Ross, or Janglebox, and it has the "attack" control. When I built mine I busted out the input trim to an external knob and you can use that as a threshold control.


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## Smylight (Jun 28, 2016)

I use a Keeley and like the blend control very much. It does that squashed sound but by blending in some straight signal you can put some of the attack back in.

I'll say I only use it with an electric 12, so not a comp expert here, but I like it much more than my original 70s Ross clone and my Boss CS3.


Pierre
Guitares Torvisse


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## Greenbacker (Mar 29, 2007)

I've got a Keeley Compressor Plus that I'd sell if that is of interest.

I use the EHX Black Finger tube comp. It's a monster of a thing that requires a dedicated power supply but I think it's great. It can do those ultra squashy sounds as well as some more subtle — and even a bit of overdrive.


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## Granny Gremlin (Jun 3, 2016)

Man, I've had an idea for a dirty compressor on the back burner for a while - gotta get on that.


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## telle-tom (Nov 8, 2021)

Having tried several, I have settled on two that I work best for me anyway. 

On my grab-n-go rehearsal jam board I like the exotic. 








My all time favourite for sure has been the Empress. The one compressor that has not moved off my board in years since I've had it. IMHO one of the best.


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## Starquasi (Feb 11, 2009)

I had the original keeley comp, but went to the Wampler Ego comp. Love the blend and the tone control to give me some of the top end back.


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## mhammer (Nov 30, 2007)

The Dynacomp design provided for a long gain-recovery time. That is, when you pick a note, the gain is suddenly reduced, and then gradually restored. It is the slow restoration of gain that created the* impression* of increasing sustain, even though sustain was not directly affected.

The time taken to restore gain fully, in anticipation of the next sudden peak, is partly dictated by a single 150k resistor, shown below. I can't easily tell if it is the one labelled 1 or 2, but it's one of them. On compressors made by other manufacturers, using the same basic design, that 150k resistance was replaced with a smaller value in series with a pot to provide variable resistance, from 10k up to 160k (10k+150k). At lower resistance values, full gain is recovered more quickly. The impact of this change is not noticeable if one is playing/picking/strumming slowly, since enough time passes between strums for gain to fully or mostly recover. But if you attempt to pick quickly, the attack of whatever you play right after that first pick-attack gets lost as the circuit takes its time to come back. That's why the added control was often labelled as an Attack control, even though it does not modify attack time in any way. Fender was the only company to label the control correctly as "Recovery" on their The Bends compressor pedal. I felt compelled to thank/congratulate Fender project-manager Stan Cotey for doing that when I was at NAMM, and he sincerely appreciated it.

About 2 years ago, I modded sometime forum member amagras' Dynacomp, adding a toggle to select between faster and stock gain-recovery. It was a simple matter of popping a strategically-placed hole for a small toggle switch, and wiring up two resistors to place in parallel with the existing 150k - a 56k and 12k - to be able to restore stock recovery time, or an 11k or 41k parallel value, for fast-medium-slow, with roughly equal "distances" between each setting. It's a fairly simply mod, and he felt it added new life to his pedal. The tricky part is placing the hole for the toggle *exactly* where it needs to go without being in the way of anything. Use thinner wire, and after you've tinned the wire, you can easily wrap it around the exposed parts ot the existing resistor, or solder it to the pads on the copper side.

This is functionally the same as any 3-knob pedal with an Attack control. When Tim Larwill was producing his take on the Ross compressor (essentially a Dynacomp with a few very minor changes), we discussed implementation of a gain-recovery switch, exactly as I described. I worked out the math, and he included it in the pedal. Some time later, I noticed it had been replaced with a variable control. I asked Tim about it, and he replied that customers felt "limited" by the 3 switch settings, asking for a variable control. He and I both knew that no one would ever really be able to tell the difference between the toggle and variable control, since it depends on picking speed, with most either setting the control to the 7:00 or 5:00 position. But, whatever the customer wants, the customer gets, even if they don't need it. Kudos to EHX for sticking with a 3--position toggle on their Soul Preacher compressor.

But on to the original question....

The Dynacomp uses a 3080 operational transconductance amplifier (OTA) chip. It's a classic, but has since gone out of production, and been eclipsed by other functionally equivalent chips. The weak spot of the 3080 is that it can't handle hot signals without distortion. That resulted in the need to for the design to reduce the input of the pedal, and then amplify the compressed signal to restore volume, resulting in a worse signal-to-noise ratio. Later compressors used better OTA chips but kept much of the same circuit, whch is why so many still use the 10k+150k pot gain-recovery-time control. I suppose some players like the grit that the 3080 chip provides, while others don't.

What makes something "like" a Dynacomp, but "better"? One feature is the "Attack/Recovery" control which adapts the response to one's picking style. All compressors have the characteristic of seeming to rob the guitar of the bright pick attack. Since the majority of any harmonic content of the string is in the first 100 or so milliseconds, anything that quickly pulls back on the gain within a few milliseconds, and then raises the gain as the string enters the much duller-sounding decay phase, will seem to make the resulting tone seem lifeless. One way around this has been to make the output of the pedal be a combination of compressed and uncompressed sound. This shows up as a "Blend" control. The pick attack shows up from the unaffected signal, quickly dying out, and gets combined with the duller-but-sustaining compressed sound. Many feel this gives them the best of both worlds. Some compressors will add a Tone control, though personally I don't feel the need for it.


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## DrumBob (Aug 17, 2014)

I'll take my Janglebox any day.


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## mhammer (Nov 30, 2007)

The Janglebox IS a Dynacomp, but with a few component tweaks to improve top end. It is borrowed from the compressor circuit included in one of the Rick 12-strings. I suspect the Rick preceded MXR, but I'll leave that to the historians. You'd be surprised at how many different compressors are fundamentally a modded Dynacomp. That doesn't make you wrong to like it. Its pedigree is solid.


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## Granny Gremlin (Jun 3, 2016)

mhammer said:


> The Janglebox IS a Dynacomp, but with a few component tweaks to improve top end. It is borrowed from the compressor circuit included in one of the Rick 12-strings. I suspect the Rick preceded MXR, but I'll leave that to the historians. You'd be surprised at how many different compressors are fundamentally a modded Dynacomp. That doesn't make you wrong to like it. Its pedigree is solid.



Nope - the Ric was a blatant copy of the MXR, just mounted inside a guitar. May have even been legit (licensed); don't remember. Kinda like Gibson ED-0*F* basses in the 60s which had a Maestro Fuzz under the (larger) pickguard (those were for sure legit).

My favorite, but probably most useless to the general public, onboard effect on a guitar is the Vox Repeat Percussion (Earthquaker did a take on it - The Hummingbird, but I've never tried that version). It was like a square wave tremolo (hard on/off of the signal vs a volume sweep/ramp), creating a percussive stuttering effect thast could sound somewhat delay-like, or just weird in a unique way I Iove.


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## mhammer (Nov 30, 2007)

Granny Gremlin said:


> Nope - the Ric was a blatant copy of the MXR, just mounted inside a guitar. May have even been legit (licensed); don't remember. Kinda like Gibson ED-0*F* basses in the 60s which had a Maestro Fuzz under the (larger) pickguard (those were for sure legit).
> 
> My favorite, but probably most useless to the general public, onboard effect on a guitar is the Vox Repeat Percussion (Earthquaker did a take on it - The Hummingbird, but I've never tried that version). It was like a square wave tremolo (hard on/off of the signal vs a volume sweep/ramp), creating a percussive stuttering effect thast could sound somewhat delay-like, or just weird in a unique way I Iove.


I wasn't sure. My gut said it followed the MXR, but my head said "So Mr. Smartypants, how did Roger McGuinn like it so much if all those Byrds hits came before MXR even existed?". Not saying you're wrong. Just explaining my own reasoning.


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## Smylight (Jun 28, 2016)

I seem to remember reading an interview in which Roger asked Rickenbacker to put a compressor into his signature model, but this was long after the Byrds’ heyday. Like George, he used outboard studio compressors back in the day.


Pierre
Guitares Torvisse


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## Granny Gremlin (Jun 3, 2016)

mhammer said:


> I wasn't sure. My gut said it followed the MXR, but my head said "So Mr. Smartypants, how did Roger McGuinn like it so much if all those Byrds hits came before MXR even existed?". Not saying you're wrong. Just explaining my own reasoning.





Smylight said:


> I seem to remember reading an interview in which Roger asked Rickenbacker to put a compressor into his signature model, but this was long after the Byrds’ heyday. Like George, he used outboard studio compressors back in the day.
> 
> 
> Pierre
> Guitares Torvisse



Exactly. The Dynacomp came out in 72 and Roger's sig Ric 12 string was 88.


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## loudtubeamps (Feb 2, 2012)

Hello my name is Doug..... I am a compressor junkie.
I've tried just about everything out there.
For the op....Keeley compressor plus which fattens and sustains very well. Very quiet at most settings.
Most of the time , I use the Empress....I like what it does when the volume on the guitar is backed off.
I do use the Boss CS2 as a subtle squish and a not so subtle boost...I have one mounted in each of my guitars along with a 9v rechargeable and a true bypass mini toggle.
They fit nicely into a Godin RG3 and a Heritage H 140.....my secret weapon.🤫😎


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## BMW-KTM (Apr 7, 2015)

Keeley or Wampler would be my choice these days.
I prefer compressors that have a "blend" feature.


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## DavidP (Mar 7, 2006)

What @BMW-KTM said...


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## mhammer (Nov 30, 2007)

Yep. "Blend" accomplishes much of what folks hope to achieve with the "Attack" control.


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## Midnight Rider (Apr 2, 2015)

Acquired this 1978 MXR dyna comp block letter from J.Geils in 1979 and still use it today.


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## mhammer (Nov 30, 2007)

Sweet. Good genes.

Note a few things about the unit:

It does not provide true bypass, as was true of pretty much all pedals of that era. Many were designed to factor in the "loading" down of the input, that was never disconnected from the circuit board, and maintain an effect/bypass volume balance. Not the case with those circuits that were capable of great boost, in some instances when people would try and convert pedals of that era to "true bypass", they would experience a volume difference between effect and bypass modes.
the switch, jacks, and pots are all larger than what is typically used nowadays, leaving precious little space for the circuit board in that size of enclosure. MXR adapted to these constraints by use of ceramic disc capacitors and tantalum capacitors (the blue ones and brown one) which they could easily bend over to lie flat. You'll note that the transistors themselves are also bent over to lie flat. Much of MXR's "design philosophy" was to produce a circuit board that had as low a profile as possible.
The pots and stompswitch were good quality. Not that there were many other choices at the time, but that's why these things still hold up so well. My experience with contemporary pots of smaller diameter is that the smaller the diameter, the worse the wiper (the internal contact that gets moved around). Wipers on bigger pots make more "polite" contact with the resistive strip, resulting less long-term wear and abrasion of the strip. That Dynacomp is over 40 years old. I do not expect pedals made today to be still working 40 years hence, without replacing the pots.
No external power jack or status LED. When one's "pedalboard" consisted of 2, maybe 3, pedals connected by patch cords and lying on the floor (an Indian print throw rug if you were a big shot), replacing worn out batteries was not a hardship. Moreover, the standard power supply of the time was generally designed for powering a desktop calculator, rather than audio equipment of any sort, and so was not especially well-regulated (i.e., did not reduce hum low enough to be comparable to battery power). Addtionally, the most common type of power jack, when there WAS one, was a 1/8" mini phone jack. The issue that posed was that people would often forget to insert the plug *first*, before plugging the wallwart into the wall or power bar. During insertion, a "live" power plug would short out the hot tip and ground, producing an impressive light display. The 2.1mm barrel type, that came in with Boss and eventually everyone else, was a godsend.


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## Midnight Rider (Apr 2, 2015)

Website Link - ElectroSmash - MXR Dyna Comp Analysis

*MXR Dyna Comp Analysis*
The MXR 102 Dyna Comp is a compressor effect guitar pedal, released in 1972 by MXR and rapidly becoming popular because of its price and ease of use. The electronic circuit was also used as a reference design on many other compressor effects like the Ross Compressor, T-Rex CompNova, Ibanez/Maxon CP5/CP9/CP10 and boutique pedals. This model is neither the most silent nor the most hi-definition piece of gear but it has real character and it's easy to find.

This pedal produces dynamic range compression, this is basically smooth out volume differences between notes; giving more body and level to weak notes so the sound does not change drastically no matter what the real signal level is, giving better articulation and sustain to the guitar. The pedal also adds its own coloring and tone to the signal.



*Table of Contents:*



1. MXR Dyna Comp Schematic.
1.2 MXR Dyna Comp Part List / Bill of Materials.
1.3 MXR Dyna Comp PCB Layout. 
2. Power Supply Stage.
3. Input Buffer.
3.1 Input Buffer Frequency Response.
4. The OTA Amplifier.
4.1 The OTA Chip: CA3080.
5. Envelope Detector Block.
6. Output Stage.
7. Resources.



*1. MXR Dyna Comp Schematic.*

To make the circuit easier to understand, it is divided into 5 blocks: Input Buffer, OTA Amplifier, Envelope Detector, Output Stage and Power Supply:



The main design idea is this: The Input and Output Buffers isolate the circuit, keeping good signal integrity. The core of the circuit is the OTA amplifier, this part will give higher or lower amplification to the signal. In order to decide the amount of amplification, the Envelope Detector will measure how big or small the guitar signal is at a time and gives to the OTA a current feedback proportional to the guitar level, amplifying weak signals.The simple Power Supply provides energy and bias points to all the circuit parts.

*note:* The circuit is redrawn trying to make it simpler. Usually, the _Envelope Detector_ stage is represented in parallel looking like aLong Tailed Pair or a Differential Amplifier that could be misleading.



* 1.2 MXR Dyna Comp Part List / Bill of Materials.*

The parts in the design are not critical, you can use substitutes for the transistors (2N3904) or the silicon diodes (1N914). The only part which is not so easy to find nowadays is the CA3080 IC.



C1 0.01uF
C2,C3 1uF
C4,C6,C7  10nF
C5 1nf
C8,C10,C11 10uF
C9 50nF
Q1,Q2,Q3,Q4,Q5 2N3904
D1,D2 1N914
D3 1N4148
RV1 500K
RV2 50K
Rtrimmer 2K
R1,R3,R9,R10,R14 10K
R2,R4,R6,R11,R12 1M
R5 470K
R7 15K
R8,R13 150K
R17 27K
R15 56K
R16 22K
U1 CA3080
J1, J2 Audio Jacks



*1.3 MXR Dyna Comp PCB Layout. *

The original MXR Script model which is not available nowadays uses the classic MXR white/yellow PCB with a distinctive shape. It was a one layer PCB with all the components on one side. When Dunlop acquired MXR in 1987, the PCB was progressively redesigned using modern materials/components and a double-sided PCB with red solder mask. 



*2. Power Supply Stage.*

The Power Supply block provides +9V supply to the circuit components and also an unusual bias of +2.5V with resistor divider (R15 and R16) to be used as a virtual ground to the CA3080 and also as a bias voltage for the transistor stages:




Seems that the original design did not include decoupling caps in the power supply, but a moderate-high value 10uF caps (C10 and C11) could be included to remove noise from the power supply line.
A protection diode D3 helps against reverse polarity connection. Some schematics include this diode in series and some in parallel with the 9V source, both ideas will work fine.
A stereo guitar input jack could be used as an on-off switch, connecting the battery (-) pin to ground when the mono guitar jack is plugged.
*3. Input Buffer.*
The Input Buffer is implemented using a basic Common Collector (Emitter Follower) transistor circuit. It provides high input impedance and unity gain in order to preserve signal integrity avoiding high-frequency signal loss (tone sucking).



The base of the transistor is biased to 2.54V through a high-value resistor R2 (1MΩ).
The input series resistor R1 (10KΩ) will limit the amount of current into the base of the transistor, protecting Q1 against electrostatic discharges and making the pedal more robust.
The input capacitor C1 (10nF) gives DC isolation and together with R2 (1MΩ) - R1 is ignored because 10K is much smaller than 1M - and the input impedance of the Emitter Follower (equal to 1MΩ and calculated in the next point) creates a high pass filter: 
fc= 1/2πRC = 1/(2 x 3.14 x (1MΩ//1MΩ) x 10nF) = 31.8Hz
The output of this buffer is DC isolated through the capacitor C2 (1uF). This C2 and R4 form again a high-pass filter with a cut frequency of fc=1/2πRC = 1/(2π x 1uF x 1MΩ) = 0.15Hz. This filter will DC-isolate the next stage without modifying the audio levels.

*MXR Dyna Comp - Input Impedance Calculation:*

In order to calculate the input impedance of the Emitter Follower, the hybrid-pi model can be used to analyze the small signal behavior. If you want to get all the details, please check the Tube Screamer Input Impedance Calculation, it is basically the same circuit with some changes in the components values, otherwise just stick to the general formula:


Zin = R1 + ( R2 // [rπ + (β+1) x R3])
Zin = 10K + 1M // [rπ + (300+1) x 10K]
Zin = 1MΩ


*note:* The value of β is 300 (taken from the 2N5088 datasheet), the value of rπ is very small compared with the value of (β+1)xR3 and can be considered as 0 (ignored).

Therefore, the MXR Dyna Comp input resistance is 1MΩ (almost the value of the biasing resistor R2) which accounts for almost the entire signal loading at the input and can be considered a good/high input impedance.

*3.1 Input Buffer Frequency Response.*

The plot of the Input Stage freq response shows a unity gain and a filtering of the excess of bass (dc-level), preserving a good flat response between 20Hz and 20KHz.



The low frequencies area is dominated by the high-pass filters that place two poles on 3.1Hz and 0.15Hz creating a roll-off for the low harmonics. This filters will just remove DC-offset at the input and between stages, the audio band (20Hz to 20KHz) is not touched.

*4. The OTA Amplifier.*
The OTA Amplifier is the heart of this effect.
To understand its functionality, it is important to understand the concept of how an audio compressor works:


The principle of an audio compressor is to modify the volume of the guitar signal, attenuating the peaks and reducing the span between the softest and loudest sounds. There is a defined point _threshold_ above which the signal gets reduced (contrary to distortion effects where the signal gets clipped/squashed and distorted).

The aim of the OTA is to apply a variable gain to the original guitar signal, giving more amplification to weak signals and less to the hi-level waveforms. This amount of gain is set by the current bias pin 5 of the CA3080 and generated in the next stage (Envelope Detector)




The CA3080 has a differential input, it amplifies the current differences between the inverting (-) and non-inverting (+) inputs.
The 2K trimmer resistor adjusts the bias currents of the OTA differential inputs, trying to make a perfectly balanced OTA. Imbalances in the + and - input pins can make the OTA noisy as the signal change levels. In practice, this trimmer is adjusted to the middle position and in very very very rare occasions it is adjusted to any other value.
The bias point for the inverting and non-inverting input is around 4V, the image below can help to understand how to calculate this bias point:



The input resistance of the CA3080 inputs (Zin) depends on the amplifier bias current, looking at the "input resistance VS amplifier bias current" it can be seen that the Zin has a middle value of around 1M.
With the simplified middle circuit, the bias at the input of the CA3080 (Vx) can be calculated as:

Vx= R5 *[9V/(R5+(R4//Zin//Zin//R6))] = 470 * [9V/(1M//1M//1M//1M)] = 3.1V

note: The Rtrimmer is ignored because its value is much smaller than R4, R5, R6 or Zin.

Usually, the bias point sits around 3~4V (depending on the CA3080 current bias pin)



*CA3080 input Filter.*

There is a filter in the non-inverting input: R7(15KΩ), C3(1uF) and C4(10nF) that creates a low pass filter making the frequency response to be different in each input:



The blue line (CA3080 positive input) level is slightly smaller (~1dB) than the negative input, it is due to a small signal bleed through the Rtrimmer and R5/R6. This OTA chip amplifies the voltage difference at its input pins:


The freq response at pin 2 (-) is flat.
The freq response signal at pin 3 (+) reduces the high-frequency harmonics because of the filter created by C3 (1uF), C4 (10nF) and R7 (150K).
This frequency response is very important because it tailors the tone character of the pedal. It is important to understand that the CA3080 will amplify the difference between the red and the blue line. At mid/low freqs (let's say 300Hz) the difference is small (1dB) but at high freqs (let's say 10KHz) the difference is bigger (4dB) so the output generated will be also bigger.

In the image below you can see the input voltages VS the output voltage:



As mentioned before, the output of the CA3080 will be bigger at high frequencies because the voltage difference of its inputs is also bigger at high freqs. This will give a general high freq boost to the tone of the effect.

The C5 cap (1nF) cap placed at the output of the OTA will smooth out the excess of hash high harmonics, in orange and red the difference can be observed.

This equalization is often attributed to a pre-emphasis / de-emphasis method to reduce noise (the CA3080 is a pretty noisy part) and also will give some signature to the sound of the pedal.



*MOD: *Some users lower or remove the 0.001uF C5 cap to give the circuit full or emphasized top end response (values between 100pF to 470pF or completely removing it).



*4.1 The OTA Chip: CA3080.*
The OTA is implemented using the CA3080, this part was the first commercially available OTA by RCA in 1969, manufactured also by Intersil/Harris and discontinued nowadays. 
Transconductance is a way to measure the gain of an amplifier relating the input voltage with the output current and usually designated with the letter _gm_ and measured in Siemens. In a nutshell, the CA3080 is basically an amplifier whose differential input voltage produces an output current.




We are not describing in detail how everything works inside the CA3080, there is a fantastic application note by Intersill that describes how it works, and some other works that can give you more details about the internal electronics of the IC.

* 5. Envelope Detector Block.*
This block provides the current feedback to the OTA amplifier in order to create the compression effect:




The base of the Q2 transistor is biased to 2.5V through the R8 transistor.
The C5 (1nF) capacitor removes the excess of treble, rounding the sound, there are more details in the previous _OTA Amplifier_block.
After the OTA amplifier, the guitar signal is _doubled_ using a common collector transistor in a _phase splitter_ topology, so at the points _OUT_1_ and _OUT_2_ the input signal is doubled with the same amplitude (gain=1) and opposite phase.



After the phase splitter, 2 networks in parallel will average out the guitar signal, both the positive/negative semi cycles creating a unipolar signal (because it goes from 0 to 9V). This averaged value will indicate how loud the guitar signal is:


Above image: the averaged signal in blue color (measured at the C8 cap) changes following the amplitude of the guitar signal in purple/green colors (measured after the phase-splitter at R11 and R12):


When the level of the guitar signal starts to rise (at around 1Vpp), the blue averaged signal decreases from 9V to 0V, giving less current feedback to the OTA.



The signal is high pass filtered in parallel with C6 & R11 and C7 & R12 and the diodes D1 and D2 will protect the base of the transistor from negative voltages (the diodes are just clamping diodes that ground the base of the transistor under damaging negative voltages).
*MOD:* Disconnecting C7: If you check the full schematic the output of the pedal is also connected to the emitter of Q2. The D2 diode could clip the output signal making the signal distorted, this is why some people decide to remove the bottom envelope detector (by disconnecting C7) and just use the top one. The side effect is the fact that using half-wave rectification leads to some envelope ripple on lower notes during the decay of held notes




The transistors Q4 and Q5 work as switches, when the voltage at their bases is over the Vbe (0.6V typ), the transistor will conduct allowing the current to flow through the R13 resistor (150K). The big C8 capacitor (10uF) will act as a low pass filter, making the voltage at the base of Q5 to change slowly and follow the general envelope of the guitar signal.
*MOD:* The attack mod makes the effect more flexible to play different styles of music. It can be done replacing the 150KΩR13 resistor with a 10k+150k pair in series or using a toggle switch to select different values i.e 150KΩ or 10KΩ.

*6. Output Stage.*
The output signal is taken from the emitter of the phase splitter Q2 simplifying the circuit and using less parts. 



The output series capacitor C9 (0.05uF) will remove all the DC voltage. It also forms a high past filter together with the resistor R14 and VR2.
The cut frequency of the output low-pass filter changes slightly with the level potentiometer (RV2). This fc calculation is not easy because the interaction between R14 and RV2 does not allow to use the simple formula fc=1/2piRC. However, in the real application this fc is:
fc min with (RV2 max 50KΩ) = 52Hz
fc max with (RV2 min 1) = 310Hz



*MOD: *The output series 0.05uF capacitor C9 can be enlarged to a 1uF to give to the effect a full bottom end response.

* 7. Resources.*
CA3080 Datasheet.
CA3080 Application Note (AN6668).
Don Tillman great article about the CA3080 background. (Mirror)
MXR Dynacomp mods by JC Maillet
Dyna/Ross Clones and Variations. (Mirror)


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## Nork (Mar 27, 2010)

This is interesting - i'm actually thinking of building one and can't decide which. I'm leaning towards the Keeley because of the blend option. this is good reading. tks.


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## 2112 (Dec 30, 2020)

If you like the dyna comp except for the attack, MXR makes the Super Comp...same pedal, with an attack knob.


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## basscarter (Mar 11, 2016)

Recently picked up a Saffron Squeeze and the sound/feel is fantastic - a blend control would definitely be nice, though


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