Portable analog compressor?

Hunter Hampton

Hunter Hampton

Carbonite Member
Anyone know of a portable analog compressor that could be used in conjuction with a field recorder? Or do any field recorders use an alalog compressor?

A friend of mine was curious to know as he comes from a music producing background but is starting to do some location audio work for film.

Thanks!

P.s. I dont know why he wants an analog one but I guess its because the digital compressors dont work quite as well. Maybe too noisy? Too nasty of a clamp?
 
In my experience, compression really isn't used in the field. Limiters are included on many field mixers and recorders, but on anything less than Sound Devices level gear or better, they're not clean enough to use.

If he thinks he needs compression, he's probably got his levels set too high. Generally you want to set your gains so that 0 on the mixer corresponds to -20dBFS or maybe -12 on the recorder.
 
Agree with Jordan. Effects like compression, etc, are best applied as needed in post, not when recording the master in the field. Limiting, yes. High pass filtering to remove wind and handling noise, again yes. And perhaps just a smidge of equalization in certain circumstances. But every thing else should be deferred until post where you can always change your mind. If you apply compression in the field and then later in the leisure of post where you can hear it in the context of the other tracks, if you change your mind and decide it just doesn't work as you thought it would, you're screwed. Remind your friend that location audio recording and studio music production recording are two entirely different critters.
 
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Furthermore, development of analog compressors ended several decades ago because making digital ones is SO much easier (and BETTER).

One VERY HIGHLY regarded small compressor is the FMR Audio "Real Nice Compressor". You didn't really define what you mean by "portable". Do you mean something with an internal battery that fits into your bag? Or do you mean something that isn't a big rack-mount box? The RNC falls somewhere between those cases.

http://www.fmraudio.com/rnc.htm

Yes, there are many recorders that have built-in limiting, some better than others. Some of them are horrible and should be avoided at any cost, and others are so great, you can leave them turned on all the time. But location production sound people typically try to optimize the levels for each shot and don't rely on effects like compression, limiting, etc. when recording original sound out in the field.

For that matter, I record lots of location music events multi-track digital, and I don't rely on limiting or compression, either. Set the levels properly so the sound stays in the "sweet zone" (below being clipped, and out of the noise mud.)
 
I come from a live background with a little studio recording on the side. Location work is a completely different world and there's a lot of re-learning that has to be done. It can feel like you're taking a step back to take the time and learn how to do location work, but things that may be perfectly logical in a studio or at a live gig might be completely ridiculous on set.

It's always interesting to me to discover the little things that one world takes for granted and the other has absolutely no clue about.
 
I come from both worlds so I can say: the job of the audio recording person is to RIDE the volume.
This means you have headphones on and the volume slider/pot in your hand, one of your eyes on the VU meter and the other on the scene and you ride the volume if necessary.
Compressors? no
Limiters? yes sometimes but they tend to pump if not handled correctly....and Pro´s dont use them if possible.

Richard has it all right! and I want to add my 2 cents: compressors suck! why? because hardly anybody knows how to use them and everybody does, thats why music recently is nothing but overcompressed overlimited digital acoustic warfare!

Take any recent recording and look at the waveform in any digital audio editor, what do you see? a black bar of rectangular waveforms...:Drogar-BigGrin(DBG)
 
"development of analog compressors ended several decades ago ?"
hmm what about Manley, SPL, Avalon, Summit Audio, TL audio, Drawmer, SSL, Universal Audio,... lots of top analog companies that still develop their analog products, and to be honest, no digital equals their quality but very pricey and not portable.
 
Those "retro" firebottle things are vintage designs from decades ago, kept alive at least as long as the NOS tube stock holds out. None of them qualify as "modern" analog designs that I can see. They also don't qualify under Mr. Richards' "portable" specification. Some people still prefer the sound of black vinyl LPs. No thanks, I'm having none of that.
 
vinyls still have a greater dynamic range than cds,
in the same time they tend to have more distortions, but comparing digital distortions to analog ones is a no match, digital distortions are just inaudible.
no thanks, i want the least digital stuff in my audio, even more with compression
:)

same goes for dynamic range of all analog equipment vs digital.
and by definition digital is 0 or 1, while analog still get all values between 0 and 1.
 
Richard Crowley said:
Those "retro" firebottle things are vintage designs from decades ago, kept alive at least as long as the NOS tube stock holds out. None of them qualify as "modern" analog designs that I can see. They also don't qualify under Mr. Richards' "portable" specification. Some people still prefer the sound of black vinyl LPs. No thanks, I'm having none of that.
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I'll agree they are not portable, but I don't know where you are getting your information about compressors not being modern. Almost every mic preamp that you can buy has an analog compressor because a digital compressor on an Analog to Digital recording device makes NO sense at all. None. Zero. The whole point of the analog compressor is to push the analog signal down so it fits inside the digital dynamic range.

It also makes NO SENSE in the digital world to ever have a compressor right after your input because at that point, the damage is done, with regards to input source. Granted, compressors are used for musical purposes such as affected the transient response of instruments like drums where you want to keep the initial dynamics but smooth down the bassy second part.

However, this is totally unrelated to capture. Every modern mixing board I have used including Neve consoles has analog compressors. They are used for the purpose that this audio guy is trying to use it, although that said, the advice to not use it is very sound.

I just bought a $1500 preamp a few years ago for my microphone. It's great when recording my acoustic guitar so the softer parts are louder and the louder parts softer without enhancing the digital noise of the A2D if I went the other way (compressing it after the fact).

With voice, both singing and spoken, as said, it is always best to not use compression as it ruins the dynamics since voice changes so much and the attack qualitys of different vocal formings are so different. They are probably concerned about the noise they are getting, but this is GOOD. You need ambience in a scene or it sounds wrong. Tell him to turn down the gain!

I have used a Sony PCM-D50 which has a limiter built into it that when it detects an overload, it reduced the input by 20dB as it records 2 streams at once with 2 different analog gains which allows us to take some great takes that would have other wise been lost. But more than anything, crank that gain down!

:)

To add one more example, guitar players use analog compressors as well. When built right, they add WAY LESS noise since you are essentially bringing loud parts down into the ADC range instead of bringing lower parts up which is what you do in digital compression.

(And the person who responded with the Really Nice Compressor, yeah, that has always been regarded as one of the best for what it is. I use a Focusrite professional series (not their Platinum crap) for all my analog compression).
 
grimepoch said:
I don't know where you are getting your information about compressors not being modern.
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You seem to have mis-read what I wrote. I said that analog compressors of the kind you are using as examples are not modern. Nobody can claim that a 40 year old circuit that relies of hidden caches of old tubes is a "modern" circuit.

grimepoch said:
Almost every mic preamp that you can buy has an analog compressor because a digital compressor on an Analog to Digital recording device makes NO sense at all. None. Zero. The whole point of the analog compressor is to push the analog signal down so it fits inside the digital dynamic range.
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It is simply not true that "Almost every mic preamp that you can buy has an analog compressor". Very few mic preamps have compressors (or, more typically, limiters.) As has already been observed by others, professional equipment operated by professionals does not need artifical means like limiters to keep recording levels in their proper range. Furthermore, even old traditional equipment put the compressor in the signal path AFTER the mic preamp because there are no compressors that operate at mic level. So they ALL depend on the operator knowing what they are doing and adjusting the mic preamp gain properly.

grimepoch said:
It also makes NO SENSE in the digital world to ever have a compressor right after your input because at that point, the damage is done, with regards to input source
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Indeed. The original question was vague enough that several of us took different approaches at guessing the context and the missing parts of the question.
 
Using a compressor in a field recording will only result in the noise floor fluctuating, and being loudest when you need it to be quietest - when nobody is talking. He wants to apply studio techniques to a field situation and it's just the wrong way to go about it. I too am an audio engineer who has moved to video/location production. In a studio there usually is very little noise happening in the room, so a compressor can do it's job without causing hiss to be accentuated much. But in the field it's a different story.

Best case is to use a quality mixer with limiters, like the Sound Devices MixPre (for 2 channel). It will get the result he wants without adding noise. Rember compression and limiting are the save thing applied at different levels. If he can record in 24 bit he will have more headroom, enabling him to set the record levels lower and therefore protecting against clipping, which is the main thing to worry about with field recording.

I know of no portable analogue compressors for mics, but if he insists on playing out this flight of folly, he could buy some cable adapters and and purchase a quality stomp box compressor like the "EBS Multi Comp" for each channel he needs. It has a split compressor that will compress the lows separately from the highs - and that prevents some pumping. But man, just compress in post like the pros do.

Why risk coloring your recording in a way you can't reverse?
 
PS the MixPre has limiters on the input as well as the output. When calibrated with a camera or recorder your signal is virtually unclippable.
 
Richard Crowley said:
You seem to have mis-read what I wrote. I said that analog compressors of the kind you are using as examples are not modern. Nobody can claim that a 40 year old circuit that relies of hidden caches of old tubes is a "modern" circuit.



It is simply not true that "Almost every mic preamp that you can buy has an analog compressor". Very few mic preamps have compressors (or, more typically, limiters.) As has already been observed by others, professional equipment operated by professionals does not need artifical means like limiters to keep recording levels in their proper range. Furthermore, even old traditional equipment put the compressor in the signal path AFTER the mic preamp because there are no compressors that operate at mic level. So they ALL depend on the operator knowing what they are doing and adjusting the mic preamp gain properly.



Indeed. The original question was vague enough that several of us took different approaches at guessing the context and the missing parts of the question.
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When did I say the compressor/limiter goes before the mic preamp? Most of the expensive preamps I have either seen or used have the compressor/limiter even after an isolation circuit being either electronic, like transformer isolation, or through an optical coupler.

Maybe you are looking at this from a film position and from film sound acquisition devices, and from that end I cannot really comment as I've not used a lot of the more expensive field mixers. From the portable recorders I've used, the Sony PCM-D50 being the example I used, it has a limiter and has 2 analog recording paths per channel that one is 20dB less than the other in case an accidental spike, it can recover the waveform in that area. I tested it, worked pretty darn good.

You talk about professionals *knowing* levels when they are recording, but in special circumstances, like recording live events, having 20 to 30 channels into a board that you are recording is WAY too much to be able to manage usually by one person without certain help for when recording. Typically in those cases the protection is right before the amps, but when recording, I have seen MANY people use compressors or limiters in the recording path as a final protection for situations where something unexpected could happen. And many times it does happen because someone breaks a cable, or any variety of situations that can occur.

I mean, I agree again as I said that I would NEVER use a compressor with anything film related (except music) because it bounces the noise as mentioned, which is one of the things people HATE about cameras like the 7D with its AGC in camera (which bounces the noise).

But professional equipment wise, I'm sorry, but you are incorrect. Compressors are used in the recording chain before the analog to digital converter to tame high dynamic range signals that wont fit easily in 24-bit audio without causing the ADC noise floor to get pulled up into the sound. For acoustic instruments and recording drums, I've heard it make a world of difference. Some people are fine with adding in the extra noise, but I am usually not. I judge each performance with each instrument and decide what sounds best for the end product. If the musician is playing too soft along with harder parts, sometimes I need to compress them analog to tame their playing.

Examples of professional non-tube compressors are the Really Nice Compressor, Chandler limited Germanium Compressor, SSL G compressors, dbx compressors, ART compressors, focusrite compressors, Empirical Labs Distressor which is one of THE most popular compressors that is all analog and NO tubes although it does model tubes, Avalon compressors, joeMeek compressors to just name a few, I could go on.

Most of these companies also make preamps for mics, and most of them have compressors and EQs built into them as well. They usually come as a package, although the REALLY EXPENSIVE boutique models might just have the mic pre.

And believe me, I know digital compression as I also use the UAD2 cards which sound fantastic, but there is a reason people like tube sound. It saturates more pleasantly than other methods. While digital emulation is coming A LONG way and for almost 95% of the uses is hard to distinguish, I can say for things like guitar amps, the real thing is still hard to beat. My line6 XTpro really has nothing on a Bogner amp and cabinet combo. Feeding multiple marshal tube amps together produces a tone that is SO MUCH MORE pleasing then trying to emulate it.

That said, to the original poster, tell him NO COMPRESSOR! :) compressor does not dance! :)
 
Hey Guys,

I'm the guy Hunter was talking about...lol! Thanks for the great discussion on this thread, I have learnt a lot from it. I think my initial thought to get a compressor for the field stemmed more from wanting to get ride of the transients that were clipping my signal than to really crunch down the waveform. But after reading this, I defiantly had a 'duh' moment. The compressor would bring up the floor noise which I am trying to get rid of as well as make the signal louder.

I think in retrospect, what I would love to get for the field is an analogue limiter to boost the signal to it's max with no distortion. I am not a big fan of riding the gain, it brings up the ambient noise too (and that starts to sound inconsistent) it's also hard to predict when someone is going to speak a word really loud.

Basically, how can I record, in the field, the cleanest, loudest, and most natural sound free from hiss and clipping? Going from the studio into the wild out doors is a tough change...
 
Sloan Inns said:
Hey Guys,

Basically, how can I record, in the field, the cleanest, loudest, and most natural sound free from hiss and clipping? Going from the studio into the wild out doors is a tough change...
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Welcome to the world of location sound. I, too, came from a studio and live music environment and location sound is the hardest thing I've ever done with audio.

Here's what's been working for me.

I have not found any alternative to riding the gain. However, within a take or two, I get a feel for how the actor is going to deliver, and I'm often using my boom position to make slight adjustments for level, without being so extreme as to alter the amount of ambient being picked-up. I use this a lot when the actor goes from some whispering line to a primal scream. Lastly, I engage the limiter, and adjust my gains so the limiter is only being tickled on loud transients. As with all location sound, how well this worked is entirely dependant on very good boom position. In my work, I have found anything beyong about 24" is going to be trouble.

Also, I record a good amount of room tone, and then in post, the dialog tracks are stripped of everything but dialog. The room tone is layed in and adjusted for level so it matches the loudest level of ambient found in dialog phrases. Finally, additional fx are added to help solidify the location being depicted. The fx are usually brought in strong at the beginning of the scene for anchor, and then backed-off as dialog progresses.
 
Sloan Inns said:
Hey Guys,

I'm the guy Hunter was talking about...lol! Thanks for the great discussion on this thread, I have learnt a lot from it. I think my initial thought to get a compressor for the field stemmed more from wanting to get ride of the transients that were clipping my signal than to really crunch down the waveform. But after reading this, I defiantly had a 'duh' moment. The compressor would bring up the floor noise which I am trying to get rid of as well as make the signal louder.

I think in retrospect, what I would love to get for the field is an analogue limiter to boost the signal to it's max with no distortion. I am not a big fan of riding the gain, it brings up the ambient noise too (and that starts to sound inconsistent) it's also hard to predict when someone is going to speak a word really loud.

Basically, how can I record, in the field, the cleanest, loudest, and most natural sound free from hiss and clipping? Going from the studio into the wild out doors is a tough change...
Click to expand...

I can say only one thing, I feel your pain :) I did the same thing, as I was used to studio recording and paying SO close attention to the noise floor, building sound booths, etc, that when I did my first audio job, I was FREAKING out. What's all this noise? :)

What helped me was this. I watched a bunch of movies and television shows in headphones so I could hear what the sound was like. What I realized, is that 'hiss' we like to call it is actually the ambience in the scene that makes it feel natural and not recording in a studio.

After using my equipment for awhile, what I found was, I always had the tendency to try and ride up the audio as loud as possible (from studio recording), but then, as I realized what I really wanted to capture was the human voice at a natural level with natural ambience, I started bringing it a lot farther down and just cranked up the headphone volume to appease my prior learning :)

Most of the good field recorders I have seen have a limiter in them. I've not seen an extra piece of gear to add this, so I'd probably look for something that has it. That said, I try to limit my use of the limiter (haha) almost completely. For me, it is there if something goes wrong and the take is really good that we want to salvage it. In the end, even with a limiter, when someone goes from whispering to screaming, it can sound unnatural because the limiter is compressing down the loud parts and making the louder voices sound weird (well, compressed) since with the limiter the ratio is so high.

Once you get a lot of practice under your belt, you'll just be able to nail the gains easily AND be able to instruct your actors you are working with to give you some test dialog that should be their loudest.

Also, this book:

http://www.amazon.com/Tools-Video-Film-Multimedia-Book/dp/159200069X

Was very helpful. I setup my studio using a sound meter to get dialog at a specific dB that sounds natural. I then played back popular movie audio and brought the voice into the same range. Then, I played back what I did and could study my gain settings and learn how to tweak what I am doing.

The battle you make with field recorders is this, your mindset is to try and minimize the ADC noise as much as possible. Since most locations are just noisy in general with ambience, there is not a lot of issue with the ADC noise unless it is a really cheap recorder. Therefore, knowing that, you do have a constant. Voice to ambience is going to stay the same no matter where your gain is. If you record with more gain, you are gaining up the ambience as well, so there is little benefit to riding the gain so high. That's why you can record a lot lower, but always making sure the actors are speaking at a proper volume that makes sense.

I will say this though, one thing to MAKE SURE, when using your boom mic is not being too far from the actors. This is essential and again, something that takes practice. When you are too far away, you receive the room reverbs at levels similar to the actual dialog and it makes it sound like a person is far away (kind of like micing a guitar from across the room to give a large room feel). This never really sounds good as most dialog sounds best clear with minimal room verb (although verb is necessary unless you want everyone to sound like they are speaking from their mind and not their mouths) :)

Hope any of this helps! :)
 
Sloan.

Let's not be so extreme here with a goal to, "boost the signal to it's max with no distortion". It's just not necessary. Boosting a signal does nothing to help you in field recording. When you turn up the level, you turn up everything right? So boosting will also boost the ambient noise as well. What you want is DYNAMIC RANGE. The best way to preserve that is to have headroom. The cleanest way to have headroom is to record in 24 bit. You can record a lower signal with less noise, then boost it all you want in post with no significant added noise. Yes a limiter is great to protect against peaks, but you don't want the limiter coloring the signal the whole time.

So what are your options? Like I said before, a mixer with limiters like the Sound Devices MixPre, which has the best limiters (input and output) out there without getting into something that costs a lot more. Now, you haven't said what you need. 4 tracks? 2 tracks? Budget? Here's what I suggest.

Sound Devices MixPre: 665.00. 2 channels. Frickin' awesome.
http://www.bhphotovideo.com/c/product/292988-REG/Sound_Devices_MIXPRE_Mixpre_Portable_2.html

Recorder
2 track: Zoom H4N is popular, but mostly menu driven. 300.00
http://www.bhphotovideo.com/c/product/669360-REG/Zoom_H4n_Handy_Recorder_Kit.html

Awesome 4 track recorder.
Edirol R-44
There is the stock one, but for just a little more there is the modified one that replaces the mic pres for very quiet ones. The B&H one is good to look at for specs etc, but you should order the Oade Brothers modifies one for the best sound. It also has decent limiters, so theoretically you could record with no mixer, but a mixer would be better.

From B&H 995.00
http://www.bhphotovideo.com/c/produ...4_R_44_Solid_State_Four_Channel_Portable.html

Oade Brothers Mod
"Concert" for music and dialogue 1,025.00
http://www.oade.com/mm5/merchant.mv..._Code=EDR44CMGND&Category_Code=EDIR44-Concert

"Super" mod for the quietest pres tuned for dialogue and nature recording. 1,055.00
http://www.oade.com/mm5/merchant.mv...ct_Code=EDR44SMGND&Category_Code=EDIR44-Super


Yes you can find better gear than this, but not for this cheap. Remember you need good mics too. Again I'm suggesting what I thinnk is the best bang for your buck.

For out doors use a shotgun. Rode has the best banf/buck ratio with the NTG-3, which is a MKH-416 clone at a much lower price.
699.00
http://www.bhphotovideo.com/c/product/563798-REG/Rode_NTG_3_NTG_3_Precision_RF_Biased_Shotgun.html

Full Kit
http://www.bhphotovideo.com/c/product/573977-REG/Rode_NTG_3_Basic_Shotgun_Microphone.html

Cheaper shotgun: Rode NTG-2 269.00
http://www.bhphotovideo.com/c/product/481528-REG/Rode_NTG_2_Condenser_Shotgun_Microphone.html

For indoor recording you need a Hypercardioid, because shotguns can sound phasey in reflective rooms.

I love the AT4053b 498.00
http://www.bhphotovideo.com/c/product/642499-REG/Audio_Technica_AT4053B.html

A compromise would be the cardioid pattern Rode NT3 (not NTG-3) cheaper than 269.00
http://www.bhphotovideo.com/c/product/233750-REG/Rode_NT3.html


You can research more, but these items (I have found) are the best bang for your buck. To go cheaper will reduce your quality significantly, to get higher quality will cost a lot more.

Good luck!
 
Some opinions.
Vinyl does have a better signal, for about 5 plays. After that you have worn off the the high feq. parts of the groove. You get more plays with really high end gear but every play is destructive no mater what you do. Well there were those laser readers but oops now your back to digital...
I could be called wrong but analog (recordings) never had the dynamic range digital has. Analog sit's on top of a sea of noise and at the top you have mechanical (or magnetic) compression. You could never get away with the low level sounds that digital can capture. Tape sounds better when saturated than digital when overloaded but that doesn't constitute added dynamic range. The effective dynamic range is between the noise and the distortion and digital wins. The real issue is that a lot of people like the "inferior" signal of tape and vinyl. That is a mater of taste. So own it say you like the sound better. It doesn't really matter what the "best" is 99.9% of the time. If it did MP3 would not exist.

And I think I posted a long thread on this somewhere before but with Tape VS "digital", it is inherently a bogus argument. Why? Because magnetism is digital. When you get down to the lowest level it either is or it isn't, there isn't any "partly magnetized" particles. Tape is just a unclocked random distribution digital signal that is read by an averaging decoder. The "problem" , if there is one, with digital systems today is not that they are digital but the way that they encode/decode the signal. And electrons come in a finite size also so all electrical signals are also inherently digital.

Compressors: They are used differently in the music world than they are in production sound. In a lot of cases compressors are used to alter the sound in music production. That is exactly what you should not be doing in production. The poster who talked about listening to movies on DVD and realizing that they recorded a lot of noise and it was important, got it about 1/2 correct. Most of that ambient noise you heard (if they were big films) was added in post. But yes you don't want to go crazy trying to get a studio sound, it's not going to be possible. As a post person if I had my choice I would get production tracks that sounded totally clean and close miced. I don't want any of the "ambience" of the set on the tracks if possible. They will just get in the way of post. I spend a lot of time trying to get rid of all that stuff in post. Most sets sound nothing like what the director wants the location to sound like. Robins in a day for night scene are murder.

Limiters are often a good thing IF they stay out of the way except when that unexpected bang/ shout/ etc happens. AGC is not a limiter it is a very poor compressor like function. The problem with production sound and limiters is that you have a LOT of noise and a limiter is going to make that more of a problem. An expander could be useful, until the leading lady decides to whisper an important line. So really your best bet is to capture as clean a signal ass possible. Hot is good but clipping is not. It's a balancing act because too far down and you slide under the mud of the ambient sound (that post will try to make go away). One of the good reasons to hire someone who has some experience.

And lastly, having worked with a slew of boards big and small and an awful lot of mic preamps, I don't remember any having compression built in. THere was one but it was a pre / compressor as two units in one box. I have never seen compression on the channel strip. A lot of field mixers have limiters. And I have seen some boards with per channel limiters but not a lot. Now if your saying it's built into the A/D converter you might be right, but that's the converter not the mic pre.

The SD limiters, at least my read on the docks, look at the signal after the initial gain stage (MixPre also looks at the output) and acts on the signal before the initial gain stage. So in this case both of you are correct. The limiter is looking at a post mic pre signal but it's triggering a limiting function on the mic level signal.
 
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grimepoch said:
... They are probably concerned about the noise they are getting, but this is GOOD. You need ambience in a scene or it sounds wrong. Tell him to turn down the gain!
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Not exactly true. I mean it is, but it is NOT the production recorders job do get the ambience, that is done in post. They should be concerned if they are getting a lot of noise. But the cure is probably to get the boom in more aggressively, you want to be as close as possible.


To add one more example, guitar players use analog compressors as well. When built right, they add WAY LESS noise since you are essentially bringing loud parts down into the ADC range instead of bringing lower parts up which is what you do in digital compression.
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Two points. If it's just bringing down the top, it's a limiter not a compressor. Second "digital" compressors are modeled after analog ones and they act the same. A compressor limits the top and raises the bottom, if it's just playing with the top it's a limiter not a compressor.
 
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