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Are one knob compressors REALLY that bad?
Old 4th March 2014
  #31
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Quote:
Originally Posted by Wyllys View Post
The onus in this case falls squarely on the performer to present an effective program. This can and does include such things as:

Pre-show presence. Make the chatters and computer geeks in the coffee house aware that something is going to happen. Speak to people on the way in. Shift the focus towards audience:performer rather than just being some kind of work-place background music.

Make them be quieter, not yourself louder. Give them something interesting enough that they'll "shut up and listen".

Ask the barristas to save the steamed drinks for between numbers. Incorporate that into your performance. Take over...

Make sure your speaker (you usually only need one) is above the heads of the listeners.

Choose your singing keys so you can project. This usually means "staying out of the basement" unless you have a very, very powerful low range.

Basically, small gigs like this require a high degree of performance, much more so than a sit-down crowd who have come specifically to listen. You have to fight for your "space" and know how to hold it.

YOU MUST BE AN ENTERTAINER, not just a musician. Amplifying something in which people have little interest will only make them talk more and louder.
Thanks for the thoughtful reply. I agree with most of that but you can't totally control the environment and as a new performer I'm not about to try.

There's a poignant contrast in my town between two venues that put on new original acts. One has a mid size PA that most here would consider superior. A&H Mixwizard mixer, outboard rack with eq and compressor and 15" speakers. It sounds like mud and you can't hear quiet performers. The compressors are only on the output. I ask if it can be turned up a little. Others want it turned down. Its a noisy venue.

The other venue's PA is at its heart a Yamaha Stage pass 500 with some add ons and honestly is superior to the other PA. There is a sub added on and a small Mackie iPad mixer controls it. A Good engineer helps a lot but lets not forget he uses compression on each channel as required and the 10" speakers have MUCH more clarity. Its a smaller, quieter venue too so OK, lots of factors.

The upshot is that I still want to make the best of a small pa with at least some compression on every channel and 10" speakers.

Anthony
Old 5th March 2014
  #32
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Wyllys's Avatar
 

Anthony...

Any venue running a compressor across the mains bus is shooting themselves in the foot. The only setting which would be of any use on such a compressor would be "bypass".
Old 5th March 2014
  #33
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This is not necessarily true but we could say the same about anyone who runs a compressor on every input....

The fact that people are chatting and not listening sounds like a performance problem...not a compressor problem.
Old 5th March 2014
  #34
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ionian's Avatar
Are we talking about one knob compressors in general or one knob compressors that come with a mixer because I'm a bit confused at the moment!

As far as one knob compressors go, the SPL DynaMaxx is excellent. It also includes a one knob gate that works amazingly well.

Regards,
Frank
Old 6th March 2014
  #35
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Electrolytic's Avatar
 

Quote:
Originally Posted by Wyllys View Post
Anthony...

Any venue running a compressor across the mains bus is shooting themselves in the foot. The only setting which would be of any use on such a compressor would be "bypass".
how come Wyllys? because of reduced dynamic range?

I've recently been using super light buss compression and its brought some sense of control to the dynamics and general sounds more polished dare I say 'glue'
Old 6th March 2014
  #36
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Quote:
Originally Posted by AnthonyG View Post
I'm looking for a setup for small coffee shop/pub gigs. They can't be too loud or neighbours will complain but if they are too quite you don't get close to being heard at all over the crowd. I don't intend to compress it to the level of recorded music but I certainly want to flatten out the highs and lows somewhat so that you can be heard a little over the crowd without having the neighbours complaining about the peak volume.
As Steve-B already noted, a compressor may help reduce the peak levels but would not raise the lower levels unless you also apply make-up gain, which would increase the average level. To do what you apparently want it sounds like you'd have to apply sufficient compression to the peak levels to obtain some associated reduction in average level, allowing you to then apply some limited amount of make-up gain without causing the average level to exceed what it was initially. That could be a difficult balance to achieve in a live sound situation.

You might also want to look at the amount of perceived difference you need or want. For some reference, a halving of or 50% reduction in the perceived loudness requires about a 10dB reduction in the sound levels while a 25% reduction in perceived loudness relates to around a 4-5db reduction in SPL. A change of 3dB is generally considered the borderline being for a readily noticable change in level.
Old 6th March 2014
  #37
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Quote:
Originally Posted by Wyllys View Post
Anthony...

Any venue running a compressor across the mains bus is shooting themselves in the foot. The only setting which would be of any use on such a compressor would be "bypass".
Quote:
Originally Posted by Electrolytic View Post
how come Wyllys? because of reduced dynamic range?

I've recently been using super light buss compression and its brought some sense of control to the dynamics and general sounds more polished dare I say 'glue'
When running compression across any bus, the channel with the hottest input to that bus will trigger compression for the entire contents of that bus. This can render the compression very audible and obvious if the person mixing is not on top of everything. Of course, it all depends on how much processing is happening on the channels feeding any group bus or the mains.

The more you can go towards dealing with any "problems" at the source, the better off you should be. There may well be some legitimate use for mains bus compression, but if that's the ONLY compression you're running, then the loudest channel will control everything...and I don't think that's a good thing.

But like I said, it depends...
Old 6th March 2014
  #38
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Mains compression can drive your speakers into "thermal compression" ("longterm compression") and lead to premature deaths of voice coils due to excess heat.
Old 8th March 2014
  #39
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Quote:
Originally Posted by monocluster View Post
Mains compression can drive your speakers into "thermal compression" ("longterm compression") and lead to premature deaths of voice coils due to excess heat.
Please elaborate...
Old 8th March 2014
  #40
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Quote:
Originally Posted by Samc View Post
Please elaborate...
This is a good introduction to the concept. Also discussed nicely in the McCarthy book and the Yamaha sound reinforcement handbook.

Reader's Digest version: Compressed program material > lower crest factor > less breaks in program for driver cooling > accelerated thermal wear and tear
Old 8th March 2014
  #41
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The problem with one knob compression is there really isn't a threshold setting. I learned the "value" of this knob back in the late 80s. I brought a DBX166 and two DBX 160s to a gig. After trying the DBX 160 on vocals and winding up with more drums than imaginable in the mix and monitors, I won't use them live. Would a DBX160 work on a loud mic'd guitar amp, yeah probably. In regards to the Yamaha MG102c I actually own and use this piece of gear only for acoustic solo, one vocal one guitar live. It's actually a better DJ, keyboard mixer or something for sending a monitor mix back to. I also bring a Lexicon MX400 and Ensoniq DP/4 + and use the inserts of the Yamaha for outboard chorus/reverb/compression and gates. The compression on the Yamaha tends to kick in best at 12 o'clock. But I prefer outboard gear for compression. The weakness of the Yamaha MG102c is the pre-amps are clean but not really colored, which equates to zero analog warmth with no parametric EQ. Don't run these preamps in the red at all they will distort. But what can one expect for $85 street price? The older Mackie 1604 VLZ series sounds better and has more analog in it. I'm ready to sell some outboard to go with an X32 rack or the new X18 whenever it comes out. I really don't even like the idea of going with the brand starting with the letter "B". A decision mostly due to ease of moving gear not sound quality. I think my Mackie 1604 VLZ with my outboard would sound better. If the A&H ZED series had inserts I would have been all over it. The SoundCrafts do but they are even more money for a compact. I'll probably get a small Art Tube pre and bring it out as well. Maybe some day music manufacturers will figure out we still want the analog sound even if it's digital gear. Allen & Heath has with it's QU16 but it's also $2000.
Old 8th March 2014
  #42
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Quote:
Originally Posted by monocluster View Post
Reader's Digest version: Compressed program material > lower crest factor > less breaks in program for driver cooling > accelerated thermal wear and tear
If this were true as stated we would have dead loudspeakers at a lot of gigs and many modern CDs would fry loudspeakers.

While in theory this is possible in a very extreme and very extended situation, just strapping a comp across your main output (under normal use) will not result in this condition. The compression would have to be so extreme (that it locks the audio into a narrow bandwidth) the material would be unlistenable….and the loudspeaker driven at (or near to it's limit) for a very extended period.
Old 8th March 2014
  #43
S21
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There isn't a threshold setting on a mixer one-knob compressor, but you can tweak things a bit by running the channel trim a little hot or a little cold. Obviously that has tradeoffs.
Old 8th March 2014
  #44
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Quote:
Originally Posted by Samc View Post
If this were true as stated we would have dead loudspeakers at a lot of gigs and many modern CDs would fry loudspeakers.

While in theory this is possible in a very extreme and very extended situation, just strapping a comp across your main output (under normal use) will not result in this condition. The compression would have to be so extreme (that it locks the audio into a narrow bandwidth) the material would be unlistenable….and the loudspeaker driven at (or near to it's limit) for a very extended period.
Modern CD's are in fact more thermally demanding on the drivers than a live mix. From McCarthy, 2nd edition, pg 28, on the subject of RMS compression/limiting: Overly compressed program content 'can actually endanger the system because the lack of dynamic range causes operators searching for maximum impact to push the system into a continuous state of compression. This creates a worst-case long-term heat scenario[...]"

More resources here and here.
The effect is small unless the system is running near capacity, but it is real and documented.
Old 9th March 2014
  #45
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Quote:
Originally Posted by monocluster View Post
From McCarthy, 2nd edition, pg 28, on the subject of RMS compression/limiting: Overly compressed program content 'can actually endanger the system because the lack of dynamic range causes operators searching for maximum impact to push the system into a continuous state of compression. This creates a worst-case long-term heat scenario[...]"
But this is very different from your what you said: In this scenario people blow up systems because they push them too hard, which can happen even when there is no compression. Putting a comp across the main L & R Bus didn't cause the damage.

Quote:
The effect is small unless the system is running near capacity, but it is real and documented.
It's a non issue…only operator error or abuse will cause the damage you mentioned.
Old 9th March 2014
  #46
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Topsoe's Avatar
 

Are one knob copressors really that bad ?
In short yes , to make a one knob compressor you have to take so many decisions /compromises that you will end up with a comressor that will suit wery few operators other than yourself
Old 9th March 2014
  #47
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One knob compressors are not inherently 'bad' but they have to be used appropriately. They are not meant for everything and are not appropriate for all situations.

We can't use a small car to perform the duties of a truck and then claim that all small cars are useless when it doesn't perform well. We also can't declare that all small cars are bad after only driving (a single model) the worst small car ever made.
Old 9th March 2014
  #48
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With three sources all controlled by one person compression (one knob or otherwise) is not the problem here...performance is in my opinion.

I recently saw a four-piece combo (drums, bass, 2 guitars and vox) performing in a restaurant with such control and consistency they didn't need (and were not using) any compression. The playing level was appropriate for the situation and nobody complained.

Learning how to perform with control and consistency so you can match your performance to any given situation is more important than debating the merits of a badly made compressor.

There are times when a comp will be needed...but it shouldn't be used as a 'crutch' to replace good craftsmanship.
Old 1 week ago
  #49
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Just purchased a used Behringer QX2442USB from eBay and had to strip it down as it was DOA. Scumbag claimed it was fully working. Fault was the two 1000uF cans in the PSU on the ±15V side (totally buggered) and some noisy pots. Anyway, while I was in there I had a quick peek at the compressor sections of the main pcb. The compressor pots are dual gang and the only other givaway components I could see quickly were the 8 JFETs (suspect 2N5457). No DBX or THAT chips anywhere. So I would say that the compressors in these things are based on, or even a clone of the Yamaha circuit supplied in this thread.

Having fixed the desk I tried the compressors out and was initially really underwhelmed by them. On acoustic guitar there seemed to be severe distortion on the transient attack (clicking/buzzing) even at low compression settings. Then I tried the approach of winding the compressor pot up fairly high and then bringing the trim pot up until the compression LED fired up. I got much better results this way and the distortion was not evident. So I would suggest care needs to be taken with the gain structure to get these things to work acceptably. Just setting the channel trim until the peak light flashes and then winding back did not cut it.

The PSU design is just ****e (not very robust regulation on the ± rails) and so I suspect everything is too close to the bone to allow for any kind of sensible headroom.
Old 1 week ago
  #50
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I've used a little Behringer QXsomethingUSB mixer for years for open mic nights and crapioki - it cost well under £200 new (can't remember now!) it's been dropped countless times, beer spilled on it - used and abused and it still works perfectly well - the sound is fine, the pre's are good enough as long as you don't clip them (then they get nasty) the one knob compressors are not Fairchild 660s - but they do a job - they work pretty well on bass and to take a bit of variance out of vocals - I'd say the biggest problem with them is the granularity of the knob - it can be tricky to set the compressor where you need it - but once you've found it - they work at least as well as can be expected - much better than not having a compressor! Annnnd it has reverb+delay - which is nice. Cricky - I've spent more than that on a bottle of wine! This is dirt cheap and is tremendous value for money - what's the problem? I've never had a complaint about the sound - it can't be that bad!

I've also used an MG (12 I think) a few times - it's very similar - to the Behringer, slightly cleaner perhaps but nicer pre's, I found the single knob compressor to be no better or worse with similar issues finding the sweet-slot - but again I'd rather have that "trouble" than not have access to compression.

PS people forget some of the bloody awful small mixers we had to put up with in the 70s, 80s and 90s - from top brand-names as well. Although I remember my first gear lust was when I used to do sound for a band that had an Alice 828 - one of, if not the best, sounding small mixers I've ever heard - and the pre's were wonderful. I couldn't afford one unfortunately in the mid 80s! Not the quietest mixer - but the sound was pure syrup!

Last edited by Scragend; 1 week ago at 11:59 PM.. Reason: Added PS!
Old 1 week ago
  #51
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Quote:
Originally Posted by AnthonyG View Post
Thanks for the input. Does an Allen & Heath Zed 10 stand above the cheap brands? It doesn't have compressors or even inserts for a compressor. You would have to put the compressor between the mixer and speakers. Does that work? The A&H Zed 12fx looks better with inserts and I would be tempted to hook up a 4ch Behringer compressor but are they really better?

I've heard SOO many small PA's that were just DYING for some compression that I don't want a setup without compression.

Anthony
I have had both the behringer xenyx and Allen & Heath Zed (as well as a MixWiz).

The improvement in sound quality from the Xenyx to the ZED is astounding. It is literally night-and-day.

In a one man band, I would recommend only using compression on the vocals ... and then sparingly. If you really want vocal processing, maybe a TC Helicon. They make a nice, very easy to use, foot efx unit: https://www.sweetwater.com/store/det...n-voicetone-t1

As far as the mixer goes, you should see just how great you sound through a ZED 10fx before you go putting anything else in the signal chain. Seriously, if you are used to the sound of the Xenyx you are really in for a treat with the ZED.
Old 1 week ago
  #52
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Quote:
Originally Posted by OneEng View Post
I have had both the behringer xenyx and Allen & Heath Zed (as well as a MixWiz).

The improvement in sound quality from the Xenyx to the ZED is astounding. It is literally night-and-day.

In a one man band, I would recommend only using compression on the vocals ... and then sparingly. If you really want vocal processing, maybe a TC Helicon. They make a nice, very easy to use, foot efx unit: https://www.sweetwater.com/store/det...n-voicetone-t1

As far as the mixer goes, you should see just how great you sound through a ZED 10fx before you go putting anything else in the signal chain. Seriously, if you are used to the sound of the Xenyx you are really in for a treat with the ZED.
Thanks for the reply. This is actually an old thread that was brought back to life by Anfirmor who was giving us a run down on the electronics inside a Behringer QX series mixer that he pulled apart and repaired. Some interesting information.

Since starting this thread I decided to go digital and bought an X18.
Old 1 week ago
  #53
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Quote:
Originally Posted by AnthonyG View Post
Thanks for the reply. This is actually an old thread that was brought back to life by Anfirmor who was giving us a run down on the electronics inside a Behringer QX series mixer that he pulled apart and repaired. Some interesting information.

Since starting this thread I decided to go digital and bought an X18.
Which should also be night-and-day better sounding than a Xenyx

How are you getting along with the X18?
Old 1 week ago
  #54
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Quote:
Originally Posted by OneEng View Post
Which should also be night-and-day better sounding than a Xenyx

How are you getting along with the X18?
The X18 is great. Very powerful and I'm still leaning how to use it.
The visual frequency analyser is a very useful tool indeed to see what's going on.
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