Compressor Output Signal Level Drops When Activated Using Wireless

[dpaterson]

Hi Folks.

New to the forums here (but certainly not new to Seymour Duncan and the business of making music)!!!

I noticed something last night that's perplexing to me (and I'm sure that there is a reasonable or scientific or technical explanation for it):

I use AKG wireless for all my guitars. I go from AKG receiver into MXR Dyna Comp compressor pedal (and from there a variety of things happen depending on whether live or recording). What I noticed was that if I connect a guitar directly (using a cable) to the MXR compressor pedal then, as one would expect, the output signal from the MXR compressor pedal (it's set on maximum output) INCREASES when the pedal is turned on (I can see the levels on my sound card and within my DAW software). However: when I connect an AKG receiver to the MXR compressor pedal then the output signal from the MXR compressor pedal DECREASES when the pedal is turned on (and noticeably so too). That's the issue.

Now my own initial thoughts or notes:

The AKG receiver does boost the guitar signal if output on the receiver is set to maximum (which it always is in my case). In other words: the guitar signal output from the AKG receiver is higher than the guitar signal coming direct from the guitar itself. It is, however, possible to adjust the output of the AKG receiver from mic. level to line level (of course: at maximum output it's line level). So: is it POSSIBLE that the compressor is boosting the direct guitar signal but compressing the output from the AKG receiver??? And if so: WHY??? I would have thought that the MXR compressor pedal would simply boost whatever signal it's being given. It's a compressor not a limiter. Could this be some type of mismatch??? I've never checked the levels like this before but did notice that I got more distortion (but less sustain and feedback of course) out of my amps. with the MXR compressor pedal OFF while using my wireless system(s) and that's what prompted me to check these levels visually last night.

Any thoughts or input on the matter???

Regards,

Dale.

[VinceT]

Compressor Output Signal Level Drops When Activated Using Wireless

Don’t ‘ow the answer, but interested to read responses.

I *think* the AKG might be hitting the front end of the pedal so hard that it’s pushing it to limiting, but couldn’t tell you why for sure - I think it’s signal level.


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[dystrust]

Re: Compressor Output Signal Level Drops When Activated Using Wireless

Don’t ‘ow the answer, but interested to read responses.

I *think* the AKG might be hitting the front end of the pedal so hard that it’s pushing it to limiting, but couldn’t tell you why for sure - I think it’s signal level.


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Could also be impedance. Unless the guitar has active pickups it probably has a high impedance output, while the wireless will definitely have a low impedance output.

[dpaterson]

Re: Compressor Output Signal Level Drops When Activated Using Wireless

Hello.

Thanks so much for the prompt responses.

VinceT:

Not sure myself (obviously) but if it was limiting the signal from the AKG then the output signal from the compressor would be as high as the signal being sent out of the compressor when the guitar is plugged in directly using a cable. But this is not the case i.e. it's actually noticeable lower.

dystrust:

Nope. Not active pickups. Three guitars (Jackons) have Seymour Duncan "designed" (Jackson) humbuckers with ceramic magnets and one (Blaze VC-II) has real deal Seymour Duncan's (Alnico 5 magnets).

But assuming it's impedance: what's the fix???

The problem is that WITHOUT the compressor: the AKG systems overdrive my amps even more (and they sound WONDERFUL like this lemme tell ya) but, of course, I lose the desired compressor effect(s). And it's a problem when recording assuming that I'm not micing. up my amps. which, fortunately, is my preferred method but sometimes I muck about with the likes of Amplitube or Guitar Rig Pro (depends on the neighbour's mood that day!!! LOL!!!).

Regards,

Dale.

[devastone]

Re: Compressor Output Signal Level Drops When Activated Using Wireless

The compressor's headroom is limited by the voltage it runs on, it's not infinite. It's probably in the range of 4Vp-p (a wild-a$$ guess on my part based on the fact that it runs on 9V), it can't boost signal beyond its range. The real question is, is the boosted signal from from the guitar straight in as loud as the limited signal from the receiver? If it is hitting the limits it is also probably clipping the signal and adding distortion, try a clean signal and see if it is adding distortion.

[dpaterson]

Re: Compressor Output Signal Level Drops When Activated Using Wireless

Hello davestone.

Interesting and thanks for the response.

I shall test tomorrow (it's real late here now) and report my findings.

ACTUALLY and if the truth be told: the REAL reason that all of this started was that last night I was playing around with a clean sound (no effects) (which is something I NEVER do) and I happened to notice that there was indeed distortion being introduced but this was as a result of the gain being set too high on the transmitter and the receiver was clipping the signal in places (loud passages obviously). But at this point in time: the compressor was not even in the chain so this is a separate issue but one thing led to another after that (you know how it goes I'm sure). With distortion, of course, I never noticed that the clipping was having any effect (sounds quite good actually). But this clipping has nothing to do with the output of the receiver of course. If anything: once the gain has been adjusted correctly (to not clip) then the signal strength from guitar (wired or transmitted) should be the same not??? It's only the output of the transmitter here that could be causing an issue (maybe???)???

Of course: NOTHING is simple. If you REALLY want to get into this I also happened to notice something rather odd on the waveforms being recorded i.e. they're not symmetrical. Take a look at most any recording and the waveforms (L and R) are usually symmetrical around the 0dB line. The output from my guitars (all of them) produce an asymmetrical waveform (with or without the wireless systems and / or the compressor). I did some reading up on this and found that this COULD be "normal" but I'm not sure nor convinced. Is it??? For guitars??? Dunno. And it's not due to DC Offset either i.e. got loads of different software that I used to check this. But now I'm wondering if this anomaly could have something to do with all of this??? And what's REAL interesting is that this only shows on a clean signal i.e. when micd. up or using something like Amplitube or Guitar Rig the waveforms are "normal" (for want of a better word). Yeh I know. This is getting REAL technical now!!! LOL!!!

Lemme play around some more tomorrow and see. Somewhere in all of this there is an explanation I'm sure.

Regards,

Dale.

P.S.

Nice article here: https://www.soundonsound.com/sound-a...look-lop-sided on the above (but I think I'm getting off topic here).

Truth be told: I just have "that kind of mind" really i.e. I absolutely LOVE my own sound so this is more of a theoretical "I need to know WHY" type of thing more than anything else. This being said: the wireless / compressor issue I do need to resolve.

[dpaterson]

Re: Compressor Output Signal Level Drops When Activated Using Wireless

Good morning all.

Well: with a (relatively) fresh mind this morning I've taken another look at this and the GOOD news is that it would seem that I've given incorrect information here (well: it was correct at the time of my posting as that was my perception for whatever reason i.e. could be the late nights). The BAD news is that something else is amiss here!!!

All I did this morning was plug a guitar direct into the MXR, output set to maximum, adjusted levels in software and recorded just some strumming to test. Turns out: same thing is happening i.e. this totally independent of my wireless systems. With the MXR off levels are fine. With the MXR on: levels drop noticeably. I've attached a waveform and you'll see what I mean. Now I know it's a compressor and it's doing that just fine it would seem. HOWEVER: I've examined the stats. for the two different passages played / tests and there is at least an 8dB difference between the two. In other words: this MXR of mine is compressing and dropping the levels no matter what (whether it's set to maximum output / throughput or not). Now, of course, I don't know if this is normal for this pedal so anybody out there with more info. please post as it would be greatly appreciated. in the meantime it's probably time to get a hold of the chaps at Dunlop and see what they have to say.

And devastone:

You were right (and thanks for your post i.e. it's what gave me the idea to test this way this morning). The compressed signal (straight from the guitar) is indeed distorted!!! I checked the power requirements too (as I run my pedals off of an isolated and rectified pedal power supply unit i.e. not batteries). The MXR requires only 3.3mA and my power supply is capable of delivering 100mA or 200mA (depending on which receptacle is used). So now this leads to another question: is this pedal faulty or are the outputs from my guitars too much for it (although this I would doubt though bearing in mind that although they're high output ceramics they're not active pickups as previously noted).

Regards,

Dale.

[VinceT]

Re: Compressor Output Signal Level Drops When Activated Using Wireless

Interesting. I found this link:

https://www.electrosmash.com/mxr-dyna-comp-analysis

It’s detailed stuff. Of interest as I scanned was that there is an internal bias trimpot for the op amp - it adjusts for to balance input impedance, so it *could* be the source of your issue.

V


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[dpaterson]

Re: Compressor Output Signal Level Drops When Activated Using Wireless

Hey VinceT.

Thanks for the post and the info. Believe it or not I was reading the exact same info. just this morning. I found something else interesting (a mod):

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.

Thing is: I don't want to mod. anything (and not to mention the possible "side effect" noted). Not only that: I'd find it hard to believe that I'm the first person that's noticed this "behavior". And it is indeed a problem i.e. it's reducing the input into my amps. and mucking with my distortion (got it down to a fine art on my amps.). The pedal is obviously compressing. I just don't understand why it's lowering the overall output signal (or why it's distorting for that matter unless the above mod. is indeed the fix possibly in addition to what you found). If it's faulty then great (it's still under warranty) but if this is by design then it's going to need to be returned and replaced with something that doesn't mess with my output levels.

Thanks again.

Regards,

Dale.

[VinceT]

Re: Compressor Output Signal Level Drops When Activated Using Wireless

Hey VinceT.

Thanks for the post and the info. Believe it or not I was reading the exact same info. just this morning. I found something else interesting (a mod):



Thing is: I don't want to mod. anything (and not to mention the possible "side effect" noted). Not only that: I'd find it hard to believe that I'm the first person that's noticed this "behavior". And it is indeed a problem i.e. it's reducing the input into my amps. and mucking with my distortion (got it down to a fine art on my amps.). The pedal is obviously compressing. I just don't understand why it's lowering the overall output signal (or why it's distorting for that matter unless the above mod. is indeed the fix possibly in addition to what you found). If it's faulty then great (it's still under warranty) but if this is by design then it's going to need to be returned and replaced with something that doesn't mess with my output levels.

Thanks again.

Regards,

Dale.

Right. The Dynacomp is such a widely used pedal, that I can’t help but think something is wrong here. Definitely worth asking the Dunlop support team.


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[dpaterson]

Re: Compressor Output Signal Level Drops When Activated Using Wireless

Hello again.

Yip. Glad you're in agreement. Sent details to Dunlop this morning (along with a link to this thread) and await their response. Will definitely update here.

And all good i.e. this issue has forced to me look at some other things that I've never bothered with nor noticed before and only noticed because I was testing with a clean tone (and therein lies a good lesson - for me anyway). I've eliminated a distorted and clipped guitar signal coming into the wireless systems for one and have also learned about those asymmetrical waveforms which, by the way, are specific to pickups in my case i.e. the waveforms generated by my Jacksons are more asymmetrical than the waveforms generated by my Blaze (actually the Blaze's waveform is almost perfectly symmetrical) and this I found very interesting because the Jacksons are much brighter guitars (I call it the "Jackson Jangle") than the Blaze (which is a darker but fuller sound) and I'm guessing that there's some relation between the waveforms and the tone of the different guitars and pickups (and perhaps I'll start a new thread purely for information purposes and comments on this topic). Anyway: point is I know at least two things today that I didn't know yesterday (this in addition to the MXR issue of course) so all good.

Regards,

Dale.

[devastone]

Re: Compressor Output Signal Level Drops When Activated Using Wireless

I really don't think the pedal was intended to be run with the output max'd as "normal operation". The waveform is indeed compressed (compression works both ways, it raises the small signals and reduces the big signals), and exactly what I was expect to see from a compressor. You are most likely running out of headroom in the pedal and/or clipping the output buffer in the pedal. What do you have the sensitivity set at?

FWIW, quite a few people have intentionally used a compressor for distortion, this isn't a new discovery.

[dpaterson]

Re: Compressor Output Signal Level Drops When Activated Using Wireless

Good morning.

The sensitivity for those tests was set at only 8 'o clock i.e. almost minimum. And output was indeed on max.

I think my issue is the fact that the pedal is dropping the overall level of my output signal when on: even on max. output and min. sensitivity. And if those waveforms are examined the RMS level when on, even on max. output and min. sensitivity, drops substantially. I mean: I could understand if it was not actually boosting the output and just leaving at unity gain when on max. output and min. sensitivity but dropping the overall output level with those settings??? Doesn't make sense to me. I did try various other settings including lowering the output level and increasing sensitivity but no matter what: it drops the output level overall. Never checked if distortion disappears at a lower output level but it's certainly there with min. sensitivity. Probably the only way the distortion would disappear is if I lowered the input to the pedal by dialing back my guitars but then of course it's taking away from my amp. drive. Anyway: no response from Dunlop as yet.

As for the "discovery"??? One thing I do NOT need more of is distortion i.e. got loads of that!!! LOL!!!

Regards,

Dale.

[devastone]

Re: Compressor Output Signal Level Drops When Activated Using Wireless

Let us know what you hear!

[chadd]

Re: Compressor Output Signal Level Drops When Activated Using Wireless

As mentioned, that's exactly what I expect from a compressor. If you want the level back, put a boost on the back side to get it back.