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Conference napalm::commusic_v1

Title:* * Computer Music, MIDI, and Related Topics * *
Notice:Conference has been write-locked. Use new version.
Moderator:DYPSS1::SCHAFER
Created:Thu Feb 20 1986
Last Modified:Mon Aug 29 1994
Last Successful Update:Fri Jun 06 1997
Number of topics:2852
Total number of notes:33157

373.0. "Effects (FX) - Compressor/Limiters" by APOLLO::DEHAHN (feel the spin) Thu May 29 1986 17:41

    
    I'm shopping for a compressor/limiter for my sound reinforcement
    system, to be used mainly as a limiter protecting those valuable
    drivers. I've read through most short discussions in this file,
    and I thought it would be good to ask some of you who own them
    what you have and how you like the product.
    
    The system is used for music reproduction, so good bandwidth and
    low noise and distortion is most important. I've seen but not used
    the following:
    
    dbx 166
    audioarts
    ashley
    
    The dbx is nice, since it's stereo ( I can use one side for the
    mike since the system is mono), and has a noise gate built in.
    The ashley is pretty basic. The Audioarts is real nice, and has
    a de-esser, which would help with some of the high frequency
    overloading problems I've been having.
    
    Budget? I'm open at this point, although I'd like to keep it under
    $500.
    
    Thanks
    
    Christofer
    
    
T.RTitleUserPersonal
Name
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373.1Try SymmetrixERLANG::FEHSKENSThu May 29 1986 18:037
    I have a Symmetrix 512 that I use routinely.  I almost never notice
    it's there.  It's very flexible, and works - has no noise or distortion
    that I can detect, and has full bandwidth.  If you want specs I
    can dig them out.  It was about $350.

    len.
    
373.2dbx 160MEDUSA::ASBASMon Jun 02 1986 12:5123
         I own a dbx 160.  I use it for protecting drivers in a sound
    system.  I am a sound man for a Leominstor, Ma band.  I love the
    unit.  It gives and led readout of 'amount of compression' on one
    readout and the other readout is switchable to read either input
    level or output level.  These readouts are great, as they let you
    know exactly what's going on.  
    It is a one channel unit, but it has a
    strapping connection where you can connect two 160's together in
    a master/slave configuration and run the two off of one set of controls
    for stereo.  It can accept balanced or unbalanced inputs and outputs.
    It has an 'over easy' function which is nice.  There is also an
    output level control which can be used to  cut or boost the overall
    signal.
         I also use the unit to smooth out volume levels while recording
    onto my 4-track at home.  Noise does not seem to be a problem with
    this unit.  It has a detector circuit which is useful in various
    recording techniques, but I have not used this.  (for drums and
    special sound affects)
         I don't know the price on this unit.  I bought it second hand
    from a friend.  I have not seen a unit I like better.
         As you can tell, I strongly recommend this unit.
    
    					Mike
373.3APOLLO::DEHAHNfeel the spinMon Jun 02 1986 15:5615
    
    Thanks for the replies so far, it helps. I'm going to call NYC for
    prices on the 160, 166, and the Symmetrix.
    
    Len, I could really use those specs. Mail stop is SHR1-3/O19.
    
    I thought I saw someone with a 166 in one of the studio notes...I
    know, what can you say about a compressor/limiter...but I'd sure
    like to hear what you have to say.
    
    Thanks for the help.
    
    CdH
    
    
373.4Symetrix 501ERLANG::FEHSKENSMon Jun 02 1986 17:235
    Oops - the model number of my compressor/limiter is 501.  I'll dig
    out the specs and post them here tomorrowish.
    
    len.
    
373.5Symetrix 501 SpecificationsERLANG::FEHSKENSTue Jun 03 1986 15:1590
			Symetrix 501 Compressor/Limiter Specs

	compression ratio	RMS section:  from 1.4:1 to infinity:1
				peak section: infinity:1

	thresholds		RMS section:  -40dBm to +10dBm
				peak section: -10dBm to +20dBm

	equivalent input noise	unity gain:   < -88.5 dBu (29 microvolts)
	(600 ohm source)	-20 db:       < -98.5 dBu

	frequency response	20Hz - 20kHz, +0dB, -1dB

	maximum available	60 dB
	gain reduction

	manual attack time	.25 to 12 dB/sec
	(RMS section)

	manual release time	5 to 300 dB/sec
	(RMS section)

	automatic attack/	program dependent
	release time

	peak limiter attack	2000 dB/msec (approximately 1/2 cycle
	time			 at 50kHz)

	peak limiter release	110 dB/sec
	time

	visual indicators	10 segment LED gain reduction display,
				 accurate to within 2% of reading
				RMS above threshold LED
				Peak above threshold LED
				Output peak LED
				Power on LED

	controls		RMS threshold
				manual attack time
				manual release time
				auto/manual attack-release selector
				RMS compression ratio
				RMS compression in/out
				stereo interconnect
				side-chain select
				peak limiting in/out
				peak threshold
				output gain
				power on/off

	connectors		3 pin XLR type for balanced signal input
				 and output connections
				1/4" phone jacks for unbalanced signal 
				 input and output, side-chain equalizer
				 input and output, and stereo 
				 interconnect connections

	distortion		< .025% THD, 10dB gain reduction, 600 
				 ohm load, 1 kHz, 0 dBm output level
				< .03% THD, 10dB gain reduction, 600 ohm
				 load, 20 kHz, 0 dBm output.
				(all distortion components are 
				 primarily 2nd harmonic)

	maximum output level	+20dBm into 600 ohms or greater, unbalanced
				+26dBm into 600 ohms or greater, balanced

	minimum rated load	600 ohms
	 load impedance

	input impedance		balanced:   16.7k ohms
				unbalanced: 23.1k ohms
				side-chain:  9.1k ohms

	output impedance	balanced/unbalanced: 51 ohms
				(Note: the 501 is supplied with active 
				 differential input and output 
				 amplifiers.  A transformer balanced 
				 output utilizing the Jensen model 123-S
				 output transformer is available at 
				 additional cost.)

	physical size		1 3/4" high (1 rack unit), 19" wide,
				5" deep.

	shipping weight		7 lbs. (15/4 kg)


373.6dbx 166JUNIOR::DREHERWed Jun 04 1986 17:0886
    I own a dbx 166 and like it very much.  I got it because it has
    two channels and a noise gate on both channels which can be used
    while compression/limiting is going on.  You can also 'key' a gate
    to open from another source. 
    
    The specs:
    
    	Freq response
    		20 Hz - 20 kHz +-0.5 dB
    
    	THD (total Harmonic distortion)
    		0.2% at maximum compression, 1 kHz, 0 dBv
    
    	Equivalent input noise
    		-85 dBv unweighted
    
    	Maximum input
    		+24 dBv
    
    	Maximum output
    		+21 dBv
    
    	Input impedence
    		24 k-ohms differential
    		18.5 k-ohms unbalanced
    		Detector: 6.8 k-ohms, unbalanced
    
    	Output impedence
    		Low, single-ended, for driving 600 ohms or greater
    
    	Output gain
    		-20 to +20 dB
    
        Threshold range
    		Compressor: -40 to +20 dBv
    		Gate: +10 to -60 dBv
    		PeakStop: 0 to +21 dBv
    
    	Attack times
    		Compressor (program dependent):
    		  15 ms for 10 dB,
    		   5 ms for 20 dB,
    		   3 ms for 30 dB
    		Gate:
    		   2 ms for 28 dB (70% of return to unity gain)
    
    	Release times
    		Compressor:
    		   8 ms for 1 dB,
    		  80 ms for 10 dB,
    		 400 ms for 50 dB (125 dB/s rate)
    		Gate, slow: 100 ms for 1 dB
    		      fast: 100 ms for 100 dB
    
    	Maximum compression
    		Greater than 60 dB
    
    	Power requirements
    		90-135 V (110-V model),
    		200-260 V (220-V model),
    		50-60 Hz; 15 W
    
    	Dimensions
    		1-3/4"h x 19"w x 8"d
    
    
    	Backpanel inputs and outputs
    		Audio in (2)
    		Audio out (2)
    		Sidechain input (2)   for keying gates
    
    	Frontpanel controls
    		Gate Threshold (2)
    		Gate Release rate - fast or slow (2)
    		Compressor Threshold (2)
    		Compressor Ratio (2)
    		Gain Reduction LED's (2)
    		Peakstop Level (2)
    		Sidechain Monitor switch and LED (2)
    		Output Gain (2)
    		Bypass Switch and LED (2)
    	        Stereo Couple and LED
    
                                 
    	Price:  $400 to $450
    
373.7Maybe It Doesn't Make Any DifferenceERLANG::FEHSKENSWed Jun 04 1986 20:524
    Hmm... interesting how similar the 501 and 166 are!
    
    len.
    
373.8APOLLO::DEHAHNfeel the spinThu Jun 05 1986 11:5914
    
    I think the dbx came first, so it's Symmetrix that's doing the
    copying...
    
    I've found a used 501, Len, I'm going to take a look at it before
    the weekend. I'll also be in NYC on Saturday so I plan on hitting
    Sam Ash/Manny's/AST to check out what they have (I'm also looking
    for a 4-way crossover).
    
    Thanks much,
    
    CdH
    
    
373.9Copying or Converging?ERLANG::FEHSKENSThu Jun 05 1986 21:257
    dbx may have been around before symetrix, but I think the 501 predates
    the 166; what I had in mind, actually, was not so much copying as
    "convergent evolution"; i.e., how many really different approaches
    can you take to compressing/limiting/gating?

    len.
    
373.10Yamaha SC-2020SSDEVO::MCCOLLUMWed Jul 02 1986 16:407
    I have a Yamaha SC-2020, which I think I paid $375 for. It's a dual
    compressor/limiter with noise gates. The channels can be linked
    together for stereo compression, or one side can control the other
    for broadcast voice-over applications. I can recommend it.
    
    Peter
    
373.11should I delete this?APOLLO::DEHAHNTue Sep 16 1986 12:0910
    
    Just to let you know, I purchased a Symetrix 525 stereo comp/lim/noise
    gate. It sounded a lot better than the 166, although it's not quite
    as flexible. Couldn't beat the price...$290.
    
    Thank you all for your help, especially Mr. Feshkens for swaying
    me in the Symetrix direction...
    
    Chris
    
373.12REGENT::SCHMIEDERMon May 11 1987 22:3516
The Symetric sounds like a good beast, especially for the bucks.

Is the compression in the SPX90B pretty lame, in terms of flexibility as well
as audio quality?

The Symetrix sounds like the kind of full-feature compressor I would need for
the bass, although a noise gate might be necessary (I'll check again to see if
it's included).

Wurlitzer says that dbx isn't a real compressor; they take their noise reduction
system and put it in a big box and call it a compressor.  Apparantly they took
a completely different design approach to the typical compressor architecture.


				Mark

373.13MELODY::DEHAHNTue May 12 1987 18:1914
    
    Re: Wurlitzer - dbx
    
    I don't buy it. Maybe the $139 163x is half a dbx NR system, but
    not the better models. dbx has been building compressors for studios
    and radio stations for years, even out of discrete op amps. The
    160 series is a direct outgrowth of those early models which
    incorporate LSI and are built overseas to control costs.
    
    Sounds like another fish story to me. The 160x and 166 (stereo)
    are greaty units.
    
    Chris
    
373.14dbx is what?!?JUNIOR::DREHERPlatitudes and Folklore...Tue May 12 1987 20:209
    re: .11
    
    Sounds like a line a bullshit to sell other 'in stock' compressors.
    
    re: .12
    
    Thanks.
    
    Dave dbx_160x_and_dbx_166_owner
373.15REGENT::SCHMIEDERTue May 12 1987 22:1717
RE: .14

Yeah, they were trying to sell the Yamaha and some other fancy one that cost a
lot but didn't do anything.

Daddy's in Boston told me there's no such thing as a good compressor anymore,
because "everyone's using reverb instead" so "all the major vendors have stopped
making (high-end) compressors".

Now you see why I don't own one.  With info like that, how the hell does one
know what to buy, what's available and what to look for?

Fortunately, Len Fehskens and others have provided some very helpful information
in this file.


				Mark
373.16OOOOOclickooooooMINDER::KENTWed May 13 1987 07:3140
    
                       
    I've been running the Yamaha Gc2020B for about 6 months now.
                       
    It compresses.      
                       
    It Limits.
              
    It Ducks.
             
    It gates.          
                       
    It smooths the sound of my terrible voice, bass and good guitar.
                       
    It works !! and I would recommend it. I think this underlies the
    advantage of developing a relationship with one supplier who is
    prepared to loan you equipment to try befor you buy. All this shoping
    and phoning around is all very well but if you end up buying a piece
    of kit which doesn't serve it's purpose then its wasted money anyway.
                       
    The Yamaha does all I need. I also noticed a note somewhere else
    that said (Dave Blickstein I think) , that the Yamaha was noisey.
    I think this may be some naivety in the use of compressors. All
    the compressors I have used, If you tonk up the input volume and
    put lots of compression on they will hiss a lot when the signal
    comes through. I don't find the Yamaha any noisier then the other
    units I tried. I just got a better deal on the Yam.
                                            
  RE .-1                           
                             
  WHAT IS A GOOD COMPRESSOR ?
             
    	     				Paul 
             
             
             
             
             
             
             
373.17More info about my comments about GC2020A noiseDREGS::BLICKSTEINDaveWed May 13 1987 13:2124
>   The Yamaha does all I need. I also noticed a note somewhere else
>    that said (Dave Blickstein I think) , that the Yamaha was noisey.
>    I think this may be some naivety in the use of compressors. 
    
    This of course is quite possible.  One thing to keep in mind is
    that you have the GC2020B and what I reviewed was the GC2020A.
    
>    All the compressors I have used, If you tonk up the input volume and
>    put lots of compression on they will hiss a lot when the signal
>    comes through. I don't find the Yamaha any noisier then the other
>    units I tried. I just got a better deal on the Yam.
    
    The noise was pretty uniform through all compression settings.
    Twiddling with the input volume did have a minor effect on the noise
    level, but not enough.  The only time the noise diminished was when the 
    gate kicked in.  Also, the noise was very noticeable both in the
    presence and absence of input signal (I turned the gate off for
    these experiments).  The noise was definitely related to the compressor
    because hitting the bypass switch got rid of it.
    
    I'm planning to check out a GC2020B as well as the Symetrix and
    the DBX (?) 160.   I'll try and post a comparison.

    	db
373.18Compress-Off Time!JUNIOR::DREHERPlatitudes and Folklore...Wed May 13 1987 14:248
    With all this discussion about what's a "real" compressor, noise,
    features, stereo vs mono, etc., I think it's time to have a
    patented COMMUSIC Compress-Off.
    
    I have the dbx 160x,166, Len has the Symetrix, anybody have any
    other models to bring to a face off?
    
    Dave
373.19Multi-effects versus dedicated boxCLULES::SPEEDDerek Speed, WorksystemsWed May 13 1987 16:0217
    Re: .15
    
    Mark, 
    
    What did the person at Daddy's mean when they said "Everyone is
    using reverb instead" of compressors?  Do you think they meant that
    everyone is using multi-effects units like the Yamaha SPX-90 rather
    than buying dedicated compressors?
    
    That solution is OK while laying tracks assuming you are only
    recording one instrument which needs the effects unit.  What happens
    if you want to compress the bass but also put digital reverb on
    the snare drum?  No can do.  
    
    		Derek

    
373.20%EFX-W-INVARG Invalid ArgumentDRUMS::FEHSKENSWed May 13 1987 17:546
    Also, reverb and compression are utterly different effects.  "Everybody
    is using reverb instead of compression" just doesn't compute to
    me.                                                          
    
    len (who uses both compression and reverb)
    
373.21^C ^C ^Y ^Y JON::ROSSorigs:$15,requests:$99,Proud Mary:$999999Thu May 14 1987 15:079
    
    I usually run thru the reverb THEN the compressor if
    
    I want the SRV to sound more like my basement than
    
    (yuk) Symphony Hall. 
    
    You ever try this len?
    
373.22Toward an Algebra of Effects?DRUMS::FEHSKENSThu May 14 1987 17:2012
    Nope, I always compress first and then reverb.  Reverb is a linear
    effect, (i.e., REVERB(a + b) = REVERB(a) + REVERB(b)) but compression
    is not (i.e., COMPRESS(a + b) <> COMPRESS(a) + COMPRESS(b)), so
    the effects don't commute (i.e., REVERB(COMPRESS(a)) <>
    COMPRESS(REVERB(a))).  I.e., it will sound different depending on
    which order you apply them.  Have not (yet) found a whole lot of
    reason to make my SRVs sound "yukky".
    
    Or are you saying Symphony Hall sounds yukky?
    
    len.
    
373.23Vote for DBXTALLIS::KLOSTERMANStevie KFri May 15 1987 15:443
	I use a DBX 160x on bass.  Don't record much, but live it's great. 
You can pick up one used for around $250 if you look hard.
373.24Good for recording, tooTALLIS::KLOSTERMANStevie KFri May 15 1987 15:517
RE -1.

> Don't record much, but live it's great. 

	Actually, I just remembered.  We're using the 160 in the studio
now, too, and getting some sensational sounds.
373.25REGENT::SCHMIEDERFri May 15 1987 17:4524
It never occurred to me that the guy at Daddy's meant things like SPX90, since 
they don't sell anything like that at the Boston store so the sales puitch 
wouldn't help them at all.

I don't really know what he meant.  I think he truly meant that compression 
doesn't have as many applications now that everyone has reverb.  I guess he 
meant that most people were using compression as a substitute for reverb all 
along.  Actually, none of the explanations I can think of compute, which is 
why I haven't gone back into that store!

Len, I tried the Symetrix at Wurlitzer in Framingham two nights ago, and was 
EXTREMELY impressed by its quietness and the lack of tonal colouration.  For 
$350, it's a steal, although a compressor is still low on my priority list.

On the other hand, I tried out the Peavey Mark IV bass head amp and couldn't 
get a single sound even approaching a jazz sound, even on my fretless!  Stevie 
K verified my theory by pointing out that it has an automatic built-in 
limiter.

I like my compression when I want it, but I hate it when I don't want it!  I 
don't like manufacturers that make the choice for me!


				Mark
373.26 wanna sell anyone ?CYBORG::ROLLATue Oct 06 1987 14:178
    
    
    Anybody know how much the dbx 166 cost.
    
    Where can I get one, preferably used.
    
    Mike
    
373.27$450 new?TOPDOC::DUBEDan Dube 264-4373Thu Oct 08 1987 11:5114
    
    
>    Anybody know how much the dbx 166 cost.

We bought one new at EU Wurlitzer last year for about $450. We 
also bought JBL Studio monitors at the same time, so that price 
may vary depending on how much you buy.

Great unit! The gating and compression features have enhanced our 
recordings tremendously. Good luck finding someone who wants to 
part with one!

-Dan

373.28Symetrix 525 ??????CYBORG::ROLLAWed Oct 14 1987 17:069
    
    
    Has anybody heard or played with a SYMETRICS 525 stereo comp/lim/noise
    gate.
    
    If so, how much for this bugger ?  Is it comparable to the dbx166?
    
    
    Mike
373.29MPGS::DEHAHNWed Oct 14 1987 19:0516
    
    Read back a few replies.
    
    I've got oneadeezbuggas. Works great and is very quiet.
    
    How does it compare with a 166? Well, it doesn't have attack/release
    controls on the compressor, it's designed to be soft-knee up to
    8:1 and hard limit above that ratio. The noise gate has only a
    threshold control.
    
    I use it for vocal compression and driver protection in a
    stereo reinforcement system. For that purpose it's as close to perfect
    as you can get short of Orban, UREI, or Brooke-Siren.
    
    CdH
    
373.30sorry, I forgotMPGS::DEHAHNWed Oct 14 1987 19:065
    
    Oh yeah, I paid $290 for it about a year and a half ago.
    
    CdH
    
373.31MTBLUE::BOTTOM_DAVIDNot so famous rock starWed Dec 02 1987 11:1217
    I just ordered a symetrics 525 from East Coast Sound. I got an
    unbeatable deal on it....list is $499 I got it cash price for $349.
    $150 off list price! Profound sound, Music Emporium and Sam Ash
    couldn't come close to this price. (next best price was $389) Another
    good place to check when shopping. 
    
    East Coast Sound
    40 Maine St.
    Danbury, Ct. 06810
    (203) 748-2799
    
    I spoke with Reed.
    
    dave
                                                      
    ps: thnx Chris!              
    
373.32Compressors are boring (so far)AKOV88::EATONDWhere d' heck a' we!Tue Jul 19 1988 13:3213
	Now that I have 'wunnadeezbuggas' (I just bought an Ashley 
lim/compressor), I'm wondering how y'all use them.  Can you describe the way
you set them up in the audio chain, and on the front panel?  Do you set them
certain ways for vocals?  Change them for other uses?

	Len mentioned compression first, then reverb.  What does the audio chain
look like?  Are you saying you take a sum out, run through compressor, then 
reverb, then into the deck?

	Any help would be 'preciated.

	Dan

373.33learn by doingMPGS::DEHAHNTue Jul 19 1988 17:3534
    
    The Ashley SC-50 is a great little simple compressor. They were the
    standard mid budget unit a while ago.
    
    There is no 'right' way to use one, since there are so many things
    you can do with them, and ways to do it, that the best way for you to 
    learn how to use one is to experiment.
    
    In general, you put the compressor first, to avoid overloading
    subsequent processing devices further on down the chain. Reverbs,
    especially, don't have a lot of headroom, so you want to tame the
    signal before overloading the reverb.
    
    In general, ratios under 8:1 are compression ratios. You can vary the
    attack and release to remove the pumping and other abnormalities. Over
    8:1 is bordering on limiting, where you want very fast attack and
    release to prevent damage. In a home studio application, though, you'll
    probably want to do soft compression more than anything (like for
    vocals and mixdown) so your ratio should be somewhere between 1:1 and
    8:1, with the attack/release set to sound most natural. 
    
    To smooth out vocal dynamics, the signal should be well above the
    threshold and into compression. This avoids tripping the threshold as
    much as possible which can cause pumping. However, too much
    compreession introduces distortion and decreased frequency response,
    so go easy on it. For mixdown, you want to keep the average signal
    under the threshold most of the time. This allows greater dynamic range
    within the mix, however, since it is compressed slightly, it is more
    controlled and thus smoother sounding.
    
    Now go play!!!
    
    CdH
    
373.34O.K....AKOV88::EATONDWhere d' heck a' we!Wed Jul 20 1988 15:079
< Note 373.33 by MPGS::DEHAHN >

	Thanks, Chris.  I did some experimenting last night, but apart from some
obvious level holding, I didn't notice an awful lot of difference when I fiddled
with the knobs.  What should I be looking for?  Do I need to have it set up with
high volumes before I notice anything?

	Dan

373.35MPGS::DEHAHNWed Jul 20 1988 17:0311
    
    If it's not tripping the threshold, then it's not doing too much. If
    it's holding your level constant, and you don't hear anything else
    that's different about the music, then it's past the threshold and it's
    probably set up right.
    
    They're not real exciting tools, kinda like a hammer. You can do a
    million useful things with it but it's not gonna charm your sox off.
    
    CdH
    
373.36One At A TimeDRUMS::FEHSKENSWed Jul 20 1988 20:4613
    I compress one input (board channel) at a time, before going into
    the board.  This means I need as many compressors as I am recording
    compressed voices at one time.  Right now, this means ONE.  Once
    in the board, the signal gets EQ'd and effected.
    
    Eventually I wanna get another compressor so I can compress the
    stereo mixdown for casettes, which have farily limited dynamic range,
    especially in the bass frequencies.  Stereo compression requires
    that the compressors be linked so as to avoid abrupt changes in
    the stereo image, but my Symetrix S-501 is capable of this. 
                                                    
    len.
    
373.37MPGS::DEHAHNThu Jul 21 1988 12:0610
    
    Dual channel compressors with the 'slave' switch will use channel 1's
    input VCA to drive the rest of channel 2's circuitry. This assures that
    the two channels track each other correctly.
    
    Now if I can just figure out how to get the 'slave' to load the rack
    onto the truck.....
    
    CdH
    
373.38IAMOK::CROWLEYere lies David St. 'ubbins, and why not!Thu Jul 21 1988 12:518
    
    
    ...A technique commonly referred to as 'ducking'.  Tons of useful
    applications for it too.
    
    ralph
    
    
373.39ALmost But Not QuiteDRUMS::FEHSKENSThu Jul 21 1988 13:0013
    re .38 - no, ducking uses more or less the same mechanism but in a
    different way.  In ducking, two *independent* (i.e., not related as
    a stereo pair) signals are used, one as the master.  When the master
    comes in, the slave is dramatically gain reduced; the master is not
    itself compressed.  This is used, for example, when an announcer's
    voice over comes in and the "background" music is "ducked" so it
    doesn't interfere with the announcer's spiel.  A stereo link forces
    the compression on the two channels to track one another.  Ideally
    this should be done from a sum signal so sudden changes on the slave
    channel aren't "overlooked".
    
    len.
    
373.40MIZZOU::SHERMANincompetence knows no boundsThu Jul 21 1988 13:048
    FWIW - Right now I'm just using the MXR for mixdown as the last
    stage before the tape deck.  It's pretty uninteresting except that
    I no longer have 'hot spots' where the levels go too high.  There
    is a loss of dynamics (slight) and no apparent loss of bandwidth.
    In general, I keep the attack and release short, the stereo button
    in and clamping (?) set to 4:1.
    
    Steve
373.41just duckyMPGS::DEHAHNThu Jul 21 1988 17:0313
    
    Steve,
    
    try 2:1 next time, and set the threshold a little lower. You might get
    better dynamics that way. Or you might overload your deck. Only you
    know for sure.
    
    Len,
    
    beat me to it. 
    
    CdH
    
373.42trying to type quietly.....IAMOK::CROWLEYere lies David St. 'ubbins, and why not!Thu Jul 21 1988 17:5711
    
    
    re .39 (I think) 
    
    You're right len.  My mistake....I misunderstood what you were saying.
    That'll teach me to read notes first thing in the morning with a
    hangover!  :^)
                                                                          
    ralph
    
    
373.43MIZZOU::SHERMANincompetence knows no boundsThu Jul 21 1988 18:3114
    re: back some
    Well, I only have 4:1 and infinity:1, but the dynamics problem is
    really *extremely* minor.  The input level on the limiter has been
    set so that it only limits during the spikes, and then only a tad.
    But, the meters on the tape deck don't go into the red during the
    spikes.  By the way, when I recorded my submission for Commusic
    V, the meter went into the red most of the time (about 3 dB), which
    played back fine, but when duping caused saturation on the target
    tape (Dolby B for both tapes).  Now, it's important to me to keep
    the levels at 0dB with only occasional spikes at 3 dB.  The limiter
    helps me do that without having to mess with the other equipment
    and possibly screwing up things.
    
    Steve
373.44help getting startedNORGE::CHADWed Nov 23 1988 18:1641
I have an AudioLogic MT66 compressor/limiter (or some such model :-).
The MT66 is much like a Y* one that was about $300.  Dual channel
that can be linked to track each other for stereo or separate.
With a gate, threshold, attack, decay, input, and output on each channel.

I know nothing about such things or audio technicalities either.

I also have the D50 synth and the TX16W sampler with up to 10 outs
going into my M-160 mixer.  I have one effects box, an ART Multiverb,
with which I "effect" the various channels.

The following situation describes my goal.  Over the Thanksgiving holiday I
hope to experiment with the MT66 but I have no idea where to start.  I would
like some general pointers on where to start given the situation.

First the situation:

I want to compress everything (synths and samplers), ie, the mix so as to
not send things into my stereo that would harm it.  I also want to use it on
the mix for making tapes for folks to hear and not have their speakers make
funny noises.

Q1) Where in the chain do I put the compressor.  ON a pre or post FX send,
or from the mixer into the compressor into stereo/control-amp, or where?
(10 words or less for the answer)

Q2) ratio 

Q3) general threshold 

Q4) general input and output (hi, low, medium, etc)

Q5) general attack and decay (hi, low, medium, etc)

Q6) using the gate

Basically I want to experiment over the weekend and need a starting point.

Thanks for any input.

CHad
373.4557076::SHERMANLove is a decision ...Wed Nov 23 1988 19:2912
    FWIW - I have mine (MXR dual limiter) after the FX and before my
    audio system (cheapie stereo).  As far as settings go, I'd listen
    over headphones (speakers off) to hear the effect of each setting.
    When it sounds okay with some limiting during spikes, then try the
    speakers at a low volume.  But unless your system has level meters
    for the speakers or something, all bets are off as to how far you
    can push it before hurting your system.  My system is all 'regular'
    speakers (no piezos, no boosters).  The speakers are rated at just
    lightly above the rating of the amp, so I suspect I would have a
    hard time burning out my speakers.
    
    Steve
373.46Rane DC24 dynamic controllerSTROKR::DEHAHNFri Dec 01 1989 13:4938
    
    I just picked up a new tool that you gigging folks with sound systems
    might be interested in, it's a Rane DC24 dynamic controller, aka
    compressor/limiter/gate. It was a sad day removing the Symetrix 525
    from the rack, as it always did the job extremely well, but the DC24 
    has several features that make it different from all the others on the 
    market, features I really wanted.
    
    First thing that makes it different is that it has completely
    independent sections for gate (threshold and ratio), compressor
    (threshold and ratio) and limiter (threshold, ratio set by signal
    level). Thus I can compress the signal with a low ratio to avoid
    sonic nasties but still have a limiter set to cut the peaks. The
    limiter action is hard knee but doesn't degrade the signal until you
    get to about 24dB of limiting where it starts to chop up the signal.
    Of course, if you're driving the thing that hard you'd expect it to 
    complain.
    
    It's a two channel device like the 525, and they can be ganged for
    stereo so the VCA's track properly. The DC24 has an active 24dB/oct
    crossover which can be switched in between the channels. So you can
    process the low frequencies seperately from the highs, a very nice
    feature for those with two way active systems. This means I can get rid
    of my crossover, since it's built into the DC24. You have the option
    with the outputs after the crossover, to take them seperately (lo and
    hi), or recombine them into a full range signal. This feature lets you
    process the two frequency bands seperately but then recombine them into
    a mono full range signal.
    
    It's a one rack space device, and like all new Rane products, has an
    outboard AC supply (wierdo wall bug with a normal Edison plug). Ins and
    outs are all 3 pin and are fully balanced, which is something I was
    after since it will now drive my amps directly, fully balanced. There
    is a ground lift switch. List is $599 but I paid $380 with my
    contractor discount.
    
    CdH
    
373.47ALLVAX::SCHMIEDERFri Dec 01 1989 15:073
RE: .46

This soundfs great, but do you have info on dynamic range?
373.48STROKR::DEHAHNFri Dec 01 1989 16:5915
    
    I have all sorts of lit at home. How do you define 'dynamic range?'
    If you take the engineer's approach, you sum the difference between the
    noise floor in dB and the peak output at clipping. I believe the noise
    floor, balanced, at +4dBm is around -107 or -108 dB, but I'll check. I
    also think the clip point is at +22dB or thereabouts. So you're talking
    about 130 dB or so. Dynamic range means different things to different
    people though.
    
    One thing's for sure, it's VERY quiet. Much quieter than my big Crest
    amp and especially my board. The gate really helps here.
    
    CdH
    
    
373.49STROKR::DEHAHNTue Dec 05 1989 12:2529
    
    Some more info on the DC24 for those who asked:
    
    Exapander/gate
      threshold   -50 to +10 dB
      ratio        1:1 to 20:1
    
    Compressor
      threshold   -50 to +20 dB
      ratio 	   1:1 to 10:1
    
    Limiter threshold -20 to +20 dB
    
    Inputs
    3 pin active balanced/unbalanced 20Kohm
    Maximum input level +20dBu
    
    Outputs
    3 pin active balanced 600 ohm
    Maximum output level +26dBu
    
    THD and noise .05% at +4 dBu @ 1kHz
    IM distortion .1%  at +4 dBu
    
    Signal to noise ratio 108 dB unity gain at +20dBu 20 kHz bandwidth
      "     "   "     "    92 dB unity gain at +4 dBu "   "      "
    
    CdH