Marshall - ED-1 Compressor  [schematic]

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pedalgrinder
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Post by pedalgrinder »

yeah that is a good point you make strategically used i would agree. i've seen cases where the filtering was overkill and achieved no more. But next to boards and ic's and so on and so on as you've mentioned does make a difference. Valid point
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Post by mictester »

phatt wrote:Hello Mic,
Thankyou heaps all very helpful. :thumbsup
I can't find any schematics for the Tel-Ray or the MXR sustain but I'll keep searching.
.
Morley_Compressor.pdf
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MXR Sustain
MXR Sustain
The MXR thing is pretty good. It has a completely different characteristic to a Dynacomp, and is preferred by several guitarists I know.
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Post by pedalgrinder »

yeah that mxr does look pretty good mictester. On the marshall ed1 the c15 10uf cap that is fed by the attack pot and signal to those surrounding transisotors could you hang a 5 meg pot to earth of it for a good release control as i've seen in other compressors. I really reckon that would give you some good control over time constant that is charging that cap so in audio terms a pot of that size should give you good release control. I do have some 2 meg and 5 meg pots so i was thinking of trying it. Any thoughts on it anyone?
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Post by phatt »

mictester wrote:
phatt wrote:Hello Mic,
Thankyou heaps all very helpful. :thumbsup
I can't find any schematics for the Tel-Ray or the MXR sustain but I'll keep searching.
.

The MXR thing is pretty good. It has a completely different characteristic to a Dynacomp, and is preferred by several guitarists I know.
Thanks Mictester,
Well after all my efforts messing with a few different circuits I've come to realise that these circuits are not for me.

I have no doubt that a quality setup would be very handy in a studio but for live guitar a simple limiter maybe more use to me than most of these comp circuits.

Most axe players want the sustain though some maybe after the funky effect that some styles require in which case the Boss CS3 has the sustain I was chasing but it still kills the signal and has the glitchy choked effect that some might like.

But believe me your input was very helpful in speeding things along and getting my head around it all. :thumbsup

The kind of sustain I wished for was more along the lines of you very clever RSO circuit.
And BTW I've had it on my testboard a few times trying different ideas out.

I'm still using my old faithful *Nobels SST1 OD circuit* which suits my playing styles.

The RSO (on it's own) does not have the mid honk but the 2 together give insane sustain but by then noise becomes an issue.

I'm working on some new ideas but alas that will take many hours of testing and may require a proto build to test live.
What sounds good at home can sound crap in a live venue.
Such is life.

Phil.

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Post by merlinb »

pedalgrinder wrote:yeah that mxr does look pretty good mictester. On the marshall ed1 the c15 10uf cap that is fed by the attack pot and signal to those surrounding transisotors could you hang a 5 meg pot to earth of it for a good release control as i've seen in other compressors.
The 'attack' control on the ED (and all the other Dyna clones that have the same mod) is actually a release control. Why it ever got called attack is a mystery...

There is no easy way to add a true attack control to the Dyna circuit, because everything you do also affects other aspects of the compression. Usually it makes the threshold worse.

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Post by pedalgrinder »

i don't dispute what you say i just question it on the basis of another circuit i have seen it has confused me. the emma transmorgriffier claims to have both attack and release with the dynacomp circuit. as you can see how they have done the release and the attack i don't really get how it would have much effect on the time constant of that cap. Thats why i was thinking of taking a 5 meg to earth to make the attack function actually respond as a attack function it seems to work with some other compressors i've seen i don't see why it wouldn't do the same here. Cheers
Emma transmorgriffier compressor.jpg
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Post by merlinb »

pedalgrinder wrote:i don't dispute what you say i just question it on the basis of another circuit i have seen it has confused me. the emma transmorgriffier claims to have both attack and release with the dynacomp circuit. as you can see how they have done the release and the attack i don't really get how it would have much effect on the time constant of that cap.
Actually that circuit really does do what it says on the tin, thanks for sharing! The attack and release are slightly interactive, but for a Dyna that's as good as it gets.

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Post by merlinb »

merlinb wrote:
pedalgrinder wrote:i don't dispute what you say i just question it on the basis of another circuit i have seen it has confused me. the emma transmorgriffier claims to have both attack and release with the dynacomp circuit. as you can see how they have done the release and the attack i don't really get how it would have much effect on the time constant of that cap.
Actually that circuit really does do what it says on the tin, thanks for sharing! The attack and release are slightly interactive, but for a Dyna that's as good as it gets.
Although, a problem is that with any feedback compressor you are likely to get overshoot with longer attack times, i.e., it overcompresses just after a loud transient and goes oddly quiet for a split second. Can be a cool effect, but not always what you're after.

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Post by pedalgrinder »

see to put the whole picture together of what iam up to. I managed to get my hands on a marshall ed-1 on evilbay i liked the emphasis bit on it how it controls the side chain. then i wanted both attack release so i thought of modding it. Iam also going to change the caps on the signal path for bass. all in all it's about then as good as your going to get for bass with a dynacomp circuit as far as i can see. Any other ideas more than welcome.
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Post by pedalgrinder »

Anyhows iam going to try the 5 meg pot off that 10uf cap c15 to earth i'll keep you posted to let you know how it goes i believe it will make a really good release function. :thumbsup
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Post by mictester »

Just for amusement, I built a "Dynacomp" - type audio path (with an additional emitter follower audio output transistor). I added another op-amp in parallel with the output of the input buffer stage to drive the phase splitter transistor and the rest of the rectifier circuit. This is no a "feed-forward" compressor, and has some interesting effects available. It tends to act more as a limiter than a compressor, but with some careful adjustment gives amazingly long sustain.

I still don't like the 3080 in the signal path - it's a nasty, distorted, noisy, old-fashioned part - so I'm moving over to the BA6110 for a transconductance amp in the signal path, or a different configuration that uses the OTA in the negative feedback circuit of a good quality op-amp.

The MXR sustain circuit uses the 3080 in the negative feedback path around an op-amp, and provides really smooth, long, clean sustain. The rectifier circuit is a bit over-complicated, but the device has a similar number of parts to a "Dynacomp", and give MUCH better results.... PCB and Vero to follow!
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Post by stonefreed »

the device has a similar number of parts to a "Dynacomp", and give MUCH better results.... PCB and Vero to follow!
looking forwadr to it !

I agree with you that the dynacomp is nice but the limited headroom and distortion are a big drawback.

I still like mine but would really love to see a better performing comp.

Alf

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Post by atreidesheir »

I try not to do this, but [smilie=bump.gif]
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Post by pedalgrinder »

what are you bumping for atreidesheir the schematic is on page 1 or are you looking for a layout on this one? The other thing you can probably buy one on ebay as cheap you could build it. They don't go for much. I picked one up for $40 dollars.
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Post by atreidesheir »

I don't remember now. :oops:
I my attempt a pcb layout for the mxr sustain. I haven't seen one around.
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Post by marushio_rima »

mictester wrote:
phatt wrote:My Marshall ED is still coming out wrong in live use, it's insanely hard to find a balance between the bypass sound and when it's engaged it's ever so touchy with the dreaded hi gain hiss.
Which is not much better than the old Boss CS3 I once owned.
Phil.
The problems are the same as with all these types of compressor.

The first two constraints are that everyone seems to want their pedal to work from a 9 Volt battery, and that battery has got to last for weeks. So - we've got little headroom and little current to play with.

The next problem is the transconductance amplifier IC. The 3080 wasn't ever intended to pass audio, so it's a really poor choice. It's distorted and noisy. It also doesn't really work very well at lowered supply voltages. Also, the whole of the signal goes through it the whole time the effect is engaged.

Next we have the rectifier that derives a varying DC control voltage from the instantaneous level coming out of the 3080. The recifier will inevitably suffer from "overshoot" so either the gain of the 3080 will fall to almost nothing as the note arrives cutting a hole in the sound, or the "designer" will have slowed the attack response down to mitigate this and ended with little or no real compression. Also the range of gain control is frequently much too large, leading to ever increasing noise as notes decay.

The phase splitter in the "traditional" Dynacomp circuit also provided a low impedance output signal from the emitter of the transistor. Large signals would be clipped (in one direction) by the lower rectifier diode, and give rise to rather nasty distortion on peaks. My "Improved Dynacomp" elsewhere on this forum took the audio output straight from the 3080 through an additional emitter-follower transistor. This eliminated that nasty source of distortion. The values around the retifier were also tweaked, and there was a measure of pre- and de- emphasis added to mitigate the worst of the noise. It still isn't a very good design!

If you look at the Morley compressors, you'll see a different "gain cell" topology. They've used a good quality op-amp to pass the audio, and then varied its gain by varying the negative feedback around it with a transconductance amplifier. The range of control is reduced (it's about 18 dB max in this type of circuit), but it's enough for very effective guitar compression (which is, after all, what we're after!). You have to remember that most of the audio is passed by the good quality op-amp. The distortion (and noise) is only in the feedback loop, so is much less critical. Since they've got a quad package of good quality op-amps, they've implemented a good recifier circuit which should overshoot rather less.

Morley still get away with a 9V supply, but the performance can be radically improved if you go for a 15V supply.

My current compressor uses two gain cells cascaded, controlled by two rectifier circuits. The whole board has a 4066 for signal routing, a pair of TL 074s and an LM13700. It sounds great, and has huge amounts of sustain.

If the silliness is over on this forum, I'll put it up here later this week.


i was open my ed -1 pedal and the board use a lm13700 :shock: :shock: :shock: :shock: :shock: :shock: :shock: :shock:

http://www.ti.com/lit/ds/symlink/lm13700.pdf


the scheme is different :shock: :shock: :shock: :shock: :shock: :shock:

any idea ????? someone have another scheme with tese component for ed-1????

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Post by roseblood11 »

That's a later version. I guess the schematic is more or less the same.
The CA3080 is obsolete, so they switched to (one half of) the 13700.

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Post by marushio_rima »

roseblood11 wrote:That's a later version. I guess the schematic is more or less the same.
The CA3080 is obsolete, so they switched to (one half of) the 13700.

thanks a lot roseblood11 :applause: :applause: :applause: :applause: :applause: :applause: :applause:

iwas check and the circuit is simmilar. they change for 13700 and t072 ic , other commponent is the same but sometimes the position in the borad is different. do you think in these version the sound is better than the old one? 8) 8) 8) 8) 8) 8) 8)

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Post by roseblood11 »

No, should be the same.
I used a better opamp (opa2134) to tame the hiss a bit, but the main part is, that the OTA is in the signal path. The MXR Sustain pedal ("Comande" series) puts it into the opamps feedback loop.

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Post by marushio_rima »

roseblood11 wrote:No, should be the same.
I used a better opamp (opa2134) to tame the hiss a bit, but the main part is, that the OTA is in the signal path. The MXR Sustain pedal ("Comande" series) puts it into the opamps feedback loop.

i was change c5 with 0.22uf (ceramic \ 221) and the tc072 to ba4560 ( i had one these here ) . i was change all eletrolicts with the same value but with more voltage ( minimum 25v) because i want to test the pedal in 18v ( i made the same mod with all eletrolicts in the the guvnor 2 and the jackhammer ) . i need a new power suplly with 18v to test these 3 pedals :popcorn: :popcorn: :popcorn: :popcorn: :popcorn: :popcorn:

:horsey: :horsey: :horsey: :horsey: :horsey: :horsey:

thanks again roseblood11 :applause: :applause: :applause: :applause: :applause:

p.s.: i will buy some opa2227 to replace all tc072 in the 3 pedals :D

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