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Author Topic: Was low-flux 1/4" tape the best 2-bus compressor?  (Read 9619 times)

breathe

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Re: Was low-flux 1/4" tape the best 2-bus compressor?
« Reply #15 on: October 19, 2010, 07:11:55 pm »

Wait, so, not to sound cocky (a character flaw of mine), but was I correct in saying that 456 is +3 db at 250nWb/m?  And is the naming system (+3, +6, +9) still in reference to 185nWb/m even though no one uses MRL tapes with that reference anymore?

Nicholas



Fletcher wrote on Tue, 19 October 2010 08:56

CWHumphrey wrote on Mon, 18 October 2010 22:18

breathe wrote on Mon, 18 October 2010 16:43

  And 456 is a +6 tape, I was talking about the virtues of +3 or lower tape.




456 came along long before we were working at +6 over 185nWb/m.  You must be referring to 499.

Cheers,



Due respect, you're thinking 250 nWb/m - not 185 nWb/m

The standard alignment for 456 was 3db>250 nWb/m [which was called "+6" but was really like +5.2] and 499 [and other "elevated level" tapes that came out around the same time as Dolby SR and the unfortunate acceptance of the DASH format] was generally aligned to 6db>250 nWb/m [a.k.a 355 nWb/m]

I don't think anyone actually had a 185 nWb/m alignment tape after about 1978 - 1979


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ssltech

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Re: Was low-flux 1/4" tape the best 2-bus compressor?
« Reply #16 on: October 19, 2010, 09:44:19 pm »

I can't keep quiet any longer.

dB's are relative.

"plus three dB" doesn't MEAN anything in absolute measurement terms, so PLEASE, PLEASE PLEASE for the love of precious waveforms STOP using it as an absolute.

The ONLY time that dB is used in an absolute sense is dBA. The 'A' is for 'Absolute', in case you were wondering.

You MUST NOT EVER just say 'plus three dB' unless you FINISH the sentence. Since dB are relative (a dB is a multiplier, [x 1.122 in fact]) you must say WHAT you're multiplying.

THUS:

+3dB OVER 185nWb/m is acceptable.

+6dB over 185nWb/m is acceptable.

+3dB over 250nWb/m is acceptable.

+6dB is not acceptable.

+3dB is not acceptable.


EVERYTHING is dbB over something else. -just like Every number you can think of is half of another number... or Double another number, 0r 1.414 times another number (the square root of two, and -by mathematical good fortune, almost precisely equal to 3dB).

Unless you are unambiguous in your question, neither Fletcher or ANYONE else can unambiguously answer it.

I used to HATE trying to guess what people meant when they sent tapes with no tones and markled the box "calibtate to plus six".

That's like saying "make it double". It doesn't mean ANYTHING in absolute calibration terms, only in relative terms. -unles you state what the absolute you're referring to, you're wasting ink and time.

As for the naming system always referring to 185? -No. i used to get tapes labeled plus six over 250 (which is basically 510nWb/m) or plus three over 250, as well as "plus nine over 185" and "plus six over 185"

When a tape came in sans tones, labeled "plus six" it therefore told me NOTHING.

Keith
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MDM (maxdimario) wrote on Fri, 16 November 2007 21:36

I have the feeling that I have more experience in my little finger than you do in your whole body about audio electronics..

John Noll

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Re: Was low-flux 1/4" tape the best 2-bus compressor?
« Reply #17 on: October 19, 2010, 09:52:29 pm »

I can hear drums that were recorded overly hot on lots of 60's and 70's recordings. Some Frankie Valley hits come to mind, but those were subjected to several generations of reduction mixes so it's impossible to tell where the overload came in. I'm a big fan of the stuff recorded at Rick Hall's FAME studios and hear it on some of those as well. Splat.

CWHumphrey

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Re: Was low-flux 1/4" tape the best 2-bus compressor?
« Reply #18 on: October 20, 2010, 03:17:15 am »

ssltech wrote on Tue, 19 October 2010 18:44

I can't keep quiet any longer.

dB's are relative.

"plus three dB" doesn't MEAN anything in absolute measurement terms, so PLEASE, PLEASE PLEASE for the love of precious waveforms STOP using it as an absolute.

The ONLY time that dB is used in an absolute sense is dBA. The 'A' is for 'Absolute', in case you were wondering.

You MUST NOT EVER just say 'plus three dB' unless you FINISH the sentence. Since dB are relative (a dB is a multiplier, [x 1.122 in fact]) you must say WHAT you're multiplying.

THUS:

+3dB OVER 185nWb/m is acceptable.

+6dB over 185nWb/m is acceptable.

+3dB over 250nWb/m is acceptable.

+6dB is not acceptable.

+3dB is not acceptable.


EVERYTHING is dB over something else.




Exactly.  So, 250nWb/m is roughly 3 decibels hotter than 185nWb/m (As I remember, It's actually 260nWb/m just to confuse things).  At Larrabee, we tech's always labeled tapes as something like "+3/185nWb/m (250nWb/m)".  By putting the actually fluxivity on there as well as the elevated alignment over the reference, it helped reduce the confusion.  It wasn't until the mid 90's that I started to see +6 over 185nWb/m (355nWb/m) on a regular basis.

You could certainly print 456 at +6 over 185nWb/m, but things started to sound compressed.

Cheers,
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Carter William Humphrey

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CWHumphrey

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Re: Was low-flux 1/4" tape the best 2-bus compressor?
« Reply #19 on: October 20, 2010, 03:30:51 am »

Fletcher wrote on Tue, 19 October 2010 08:56



The standard alignment for 456 was 3db>250 nWb/m [which was called "+6" but was really like +5.2] and 499 [and other "elevated level" tapes that came out around the same time as Dolby SR and the unfortunate acceptance of the DASH format] was generally aligned to 6db>250 nWb/m [a.k.a 355 nWb/m]

I don't think anyone actually had a 185 nWb/m alignment tape after about 1978 - 1979



With all due respect, by doing the math, 370nWb/m is 6dB hotter than 185nWb/m (notice 2X185=370).  MRL made 355nWb/m tapes that were technically 5.5dB hotter than 185nWb/m.

6dB over 250nWb/m would be 500nWb/m.

By the way, in the early 90's, I took a detour into film post production and everything (2", Mag, etc.) was aligned to 185nWb/m.



Cheers,
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Carter William Humphrey

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CWHumphrey

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Re: Was low-flux 1/4" tape the best 2-bus compressor?
« Reply #20 on: October 20, 2010, 03:37:33 am »

ssltech wrote on Tue, 19 October 2010 18:44



+6dB is not acceptable.

+3dB is not acceptable.



While we're at it, I prefer +4dBu and -10dBV, not just +4 and -10.

Lately, I have noticed a number of citations in print implying that dBu and dBV are the same thing and therefore interchangeable.

No, 0dBu=.775Volts, 0dBV=1Volt.

Thank you for listening.  Carry on.

Cheers,
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Carter William Humphrey

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"Or you can just have Carter do the recording, because he's Humphrey."-J.J. Blair

johnR

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Re: Was low-flux 1/4" tape the best 2-bus compressor?
« Reply #21 on: October 20, 2010, 07:40:22 am »

dBu is more or less interchangeable with dBm however.

0dBm is the signal voltage needed to put 1mW rms into a 600 ohm load, ie. 775mV rms. The m is for milliwatt.

Now that hardly any gear has 600 ohm inputs, it's become more common to see dBu (u for unloaded). 0dBu is also 775mV rms.
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ssltech

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Re: Was low-flux 1/4" tape the best 2-bus compressor?
« Reply #22 on: October 20, 2010, 10:49:00 am »

CWHumphrey wrote on Wed, 20 October 2010 03:37

ssltech wrote on Tue, 19 October 2010 18:44



+6dB is not acceptable.

+3dB is not acceptable.



While we're at it, I prefer +4dBu and -10dBV, not just +4 and -10.


Oh... you bet your bippy!

Using terms like +4 and -10 suggests that there's a 14dB difference. -Of course, there ISN'T. -It's actually almost exactly 12dB difference.

If we substituted "1dB" with "1.122 x...", 2dB with "1.259 x...", 3dB with "1.413 x..." and so forth, people would possibly start to understand how not putting anything after the term renders it worthless as a means of communication.

Keith
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MDM (maxdimario) wrote on Fri, 16 November 2007 21:36

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Fletcher

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Re: Was low-flux 1/4" tape the best 2-bus compressor?
« Reply #23 on: October 20, 2010, 11:11:40 am »

CWHumphrey wrote on Wed, 20 October 2010 03:30

Fletcher wrote on Tue, 19 October 2010 08:56



The standard alignment for 456 was 3db>250 nWb/m [which was called "+6" but was really like +5.2] and 499 [and other "elevated level" tapes that came out around the same time as Dolby SR and the unfortunate acceptance of the DASH format] was generally aligned to 6db>250 nWb/m [a.k.a 355 nWb/m]

I don't think anyone actually had a 185 nWb/m alignment tape after about 1978 - 1979



With all due respect, by doing the math, 370nWb/m is 6dB hotter than 185nWb/m (notice 2X185=370).  MRL made 355nWb/m tapes that were technically 5.5dB hotter than 185nWb/m.

6dB over 250nWb/m would be 500nWb/m.

By the way, in the early 90's, I took a detour into film post production and everything (2", Mag, etc.) was aligned to 185nWb/m.


2 counts of "my bad" -- happens with gray hair, the emergence of "man boobies" and not having used that part of the memory process in over a decade.

You're absolutely right, 355nWb/m was the MRL equivalent of 3db>250nWb/m the 499 [etc.] alignment was 6db>250nWb/m a.k.a 3db>355nWb/m -- my bad

As for film post, an area with which I was never acquainted, I could be very wrong... in "rock and roll music" studios I never saw a 185nWb/m alignment tape... it could very well have been prevalent in the film world... I entered that world only once - as an installation tech, I never actually used one of those studios [though hanging out and building one was pretty damn cool].

-------  Keith, before you blow a vein / have an aneurism... there are commonly referred shortcuts [vernacular] in every field.  The "aligned to +6" [etc.] thing was a common abbreviation as it was generally understood [at least until the late 80's early 90's when the real "riff raff" started to filter in from the 'cordin' skools] that "+6" implied 3db>250nWb/m with far fewer sounds to recite.  

Same with the +4 / -10 thing... it was well known that the difference was 12db and change [that is until the "riff raff" started to filter in].  I guess I was just a bit lucky and got into the industry when there were real and actual professionals still involved on the music side of things [they were always in film... because that's where the money was... the "music studios" could only provide "a living" and access to show passes and the key to the tech room where the drugs were consumed].

Peace.
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CN Fletcher

mwagener wrote on Sat, 11 September 2004 14:33
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If you've spent most of your life with a few thousand dollars worth of musicians in the studio, making a decision every second and a half... and you and  they are going to have to live with it for the rest of your lives, you'll get pretty arrogant too.  It takes a certain amount of balls to do that... something around three"
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Jay Kadis

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Re: Was low-flux 1/4" tape the best 2-bus compressor?
« Reply #24 on: October 20, 2010, 11:26:20 am »

CWHumphrey wrote on Wed, 20 October 2010 00:37



Lately, I have noticed a number of citations in print implying that dBu and dBV are the same thing and therefore interchangeable.

The confusion probably comes from dBv, which IS the same as dBu - dBV is not.

ssltech

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Re: Was low-flux 1/4" tape the best 2-bus compressor?
« Reply #25 on: October 20, 2010, 02:23:18 pm »

Fletcher wrote

-------  Keith, before you blow a vein / have an aneurism... there are commonly referred shortcuts [vernacular] in every field.  The "aligned to +6" [etc.] thing was a common abbreviation as it was generally understood [at least until the late 80's early 90's when the real "riff raff" started to filter in from the 'cordin' skools] that "+6" implied 3db>250nWb/m with far fewer sounds to recite.  

Same with the +4 / -10 thing... it was well known that the difference was 12db and change [that is until the "riff raff" started to filter in].  I guess I was just a bit lucky and got into the industry when there were real and actual professionals still involved on the music side of things [they were always in film... because that's where the money was... the "music studios" could only provide "a living" and access to show passes and the key to the tech room where the drugs were consumed].

Peace.


yeah, I get ya.

The trouble (and my sensitivity to button-pushing!) began for me when 'Webber' started to market test tapes in the UK. -They were available at either 200nWb/m or 250nWb/m.

We originally had an Ampex 185nWb calibration tape which I checked against the Webber when we bought it to replace the Ampex. -I couldn't make them agree very closely, but I shrugged it off, and put it down to the Ampex probably being knackered.

-But then we started getting tapes from clients with no tones on (this is probably about the mid-1980's by now) and notes like "line-up to plus four" on them... and nothing more.

This made my life hell. We'd also bought a 250nWb Webber, and the discrepancies with the other Webber and the (now elderly) Ampex meant that we didn't trust anything. -We eventually bought a 250nWb MRL. -Guess what? -It agreed with the Ampex.

Webber could go to hell for all I cared, but they were cheap, and now we had other studios springing up who had bought Webber tapes... and just about nobody quoted WHICH reference level they were referring to, on any of the boxes.

This drove me to a near apoplectic rage on at least one occasion. -Clients who were  not just too cheap to use a decent studio, but also too cheap buy enough tape to print tones, and then the studio engineer not knowing what the hell to tell me when I call and ask what level they calibrate to.

Here's my recollection of a phone call to an owner-operator-engineer-chief-cook-and-bottle-washer from a studio in the Yorkshire area which had sprung up and had set about taking clients from us, helpfully sending them back to us for mixing, (since he "didn't believe in [translation: couldn't afford] automation, man!")

"Hey, this multitrack doesn't have any tones on it... and it just says to align to..."

"Plus four" he finished my sentence for me.

"Plus four over WHAT?" I asked.

"Plus four over the test tape" He said (implying the -"Duh!"-as if I was a moron for asking).

"Yes, but WHICH test tape?" I pressed.

"The Webber" He'd tell me, as if people should be BORN knowing this fact.

"Yes, but WHICH Webber do you use?" I urged.

"The Multitrack one" He said.

".... (the creaking sound of my knuckles whitening as my grip tightened around the telephone handset)... What. Is. The. Reference. Fluxivity. Of. Your. Test. Tape." I hissed through clenched teeth, praying that the divine, almighty and ever merciful lord would grant me the patience to not purchase a cricket bat and go around to modify his smile for him.

"Zero VU". He told me. "-But we line up to plus four over that." He added. "...that means you make it point to MINUS four." He explained, after hearing silence for several seconds.

...

If there were tones printed (you know... like you're SUPPOSED to do... in the real world... where all those "professional" people live!) this became a non-issue. They could print "plus nine over forty one and three-quarter femto-Quarads" on the box, and it simply wouldn't matter... you could just point the needle to zero VU, and trust that your playback would match whatever effort they had made on the originating machine.

-But even WITHOUT tones, you could have a CHANCE at being somewhere NEAR right... within the ball-park.

But when people started just using the dB number (in the mid-1980's was my darkest hour for being asked to psychically divine what level people had actually recorded something at) then I began my seething rants, occurring whenever people would start using decibels without the reference. -My blood pressure would soar, and my face would generally go past mere 'scarlet', and on to the shade of crimson which always seems to give interior decorators a nice warm feeling in their catalog pile around late September.

I noted with admiration that tapes from Air, from Abbey Road, From the Town House, and any number of other righteous studios used to be marked "+6/250nWb" or similar. -This used to gladden my heart, and grateful tears would well up in my eyes, crowning my quivering lower lip, as a tidal wave of gratitude overwhelmed me. -I swear that shafts of light would beam down from the skies, illuminating the box label and bathing me in a reflected golden glow, while entire string sections would spontaneously assemble themselves, and immediately launch into swirling, rhapsodic, uplifting themes, whenever I read a properly labeled box.

So... yeah... I do get overly wound up, but I'm trying to teach Nicholas IN PARTICULAR, but also anyone else who has picked up the 'enough-to-be-dangerous' habit of learning the "plus x dB"  habit... that they MUST know the number.

-And -at least until you've made enough mistakes to call yourself a 'real' engineer- the best way to make SURE that you know the number (in my opinion) is to get in the habit of SAYING the number.

Please accept my apple-hoagies for ranting, and know that all in the name of getting people to think about things to the point where perhaps one or two who read my demented ramblings maybe start to 'get' WHY it matters.

-Cheers,

Keith
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MDM (maxdimario) wrote on Fri, 16 November 2007 21:36

I have the feeling that I have more experience in my little finger than you do in your whole body about audio electronics..

CWHumphrey

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Re: Was low-flux 1/4" tape the best 2-bus compressor?
« Reply #26 on: October 20, 2010, 03:18:07 pm »

Jay Kadis wrote on Wed, 20 October 2010 08:26

The confusion probably comes from dBv, which IS the same as dBu - dBV is not.



From my research, about 1978 the NAB and the IEC standardized this.  Pro analog would go with dBu and not use dBv (note lower case) and consumer analog would go with dBV.

And yes, the difference between +4dBu and -10dBV is about 11.79dB making pro equipment's operating level almost 4 times louder than consumer.

So, are we going to hash out "over bias" next? HA!

Cheers,


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Carter William Humphrey

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CWHumphrey

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Re: Was low-flux 1/4" tape the best 2-bus compressor?
« Reply #27 on: October 20, 2010, 04:04:10 pm »

Fletcher wrote on Wed, 20 October 2010 08:11



As for film post, an area with which I was never acquainted, I could be very wrong... in "rock and roll music" studios I never saw a 185nWb/m alignment tape... it could very well have been prevalent in the film world... I entered that world only once - as an installation tech, I never actually used one of those studios [though hanging out and building one was pretty damn cool].

Peace.



In music, the MRL was always a 250nWb/m tape (Larrabee, Record Plant).  Which is funny, because if someone said, please align at "+3", we would be aligning at zero, and technically not at +3 over the MRL (Keith, I feel your pain).

As I detoured into post in 1992, sometimes it felt like I'd taken a trip with the way back machine.  We used 185nWb/m alignment tapes and some of the time, productions used Dolby A!  It seemed odd to me since we had Dolby SR.  Sometimes, there was no noise reduction.

Cheers,
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Carter William Humphrey

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Gold

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Re: Was low-flux 1/4" tape the best 2-bus compressor?
« Reply #28 on: October 20, 2010, 07:49:33 pm »

CWHumphrey wrote on Wed, 20 October 2010 15:18

Jay Kadis wrote on Wed, 20 October 2010 08:26

The confusion probably comes from dBv, which IS the same as dBu - dBV is not.



From my research, about 1978 the NAB and the IEC standardized this.  Pro analog would go with dBu and not use dBv (note lower case) and consumer analog would go with dBV.

And yes, the difference between +4dBu and -10dBV is about 11.79dB making pro equipment's operating level almost 4 times louder than consumer.

So, are we going to hash out "over bias" next? HA!

Cheers,





I don't believe this is correct. Lower case v is the consumer one referenced to .316 volts and capital V is a professional standard referenced to 1 volt.
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Fletcher

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Re: Was low-flux 1/4" tape the best 2-bus compressor?
« Reply #29 on: October 21, 2010, 03:14:32 am »

ssltech wrote on Wed, 20 October 2010 14:23


If there were tones printed (you know... like you're SUPPOSED to do... in the real world... where all those "professional" people live!) this became a non-issue. They could print "plus nine over forty one and three-quarter femto-Quarads" on the box, and it simply wouldn't matter... you could just point the needle to zero VU, and trust that your playback would match whatever effort they had made on the originating machine.


I feel your pain!!  

I would have to wager that this was about 1985 - 1986 when SONY began their hardcore entry to the "recording studio market" and purchased MCI.  The purchase was actually done in 1984, but the damage didn't really start to hit home until around '85 / '86 when it SONY's marketing strategy began to hit home.

SONY was making digital machines at that time which were got-awful expensive and they needed a larger separation between analog and digital.  In order to do this they purchased MCI -- within 2 years of that purchase multi-track machines and consoles became available for about 2/3rds of what they had been selling for prior to 1984... why?  ...so more "riff raff" could become "studio owners" and due to the sheer proliferation of analog gear "digital" would seem like a far more "exclusive" club and the "pros" would demand it [because they had large budgets to play with in the "go-go 80's" and often got a taste of the machine rental money].

So it seemed that damn near every moderately successful drug dealer started a recording studio to use as a money laundry [and cool place to show their friends].  The rate war began in earnest and thus begun the downward spiral from which we currently feel the effects [more than ever, and not bloody likely to change any time soon].

I remember getting tapes in with no tones -- first it was with no 15kHz tone, then it was a 1kHz reference tone only [usually :30], and every now and again one with nothing.  I too had a conversation with the manager of a "money laundry studio" that was brutally similar to the conversation you recanted in your original post... "just put the tone tape on the machine and make the needles point to zero, what's your problem"... and when I tried to explain that every machine performed differently I was lambasted with the most ignorant rant I had ever experienced [at the time -- remember this was a good 15 years before Gearslutz]... it was like an out of body experience.

I explained the situation to the client who arranged with "Money Laundry Recording" to allow me to come up and print reference tones.  I even trained their staff on how to print reference tones under the threat to the "Money Laundry"s manager that if another reel came to where I worked from his studio without tones we would put an ad in ALL the local papers that said we do not accept tapes for mixing that were recorded at his studio.

The beginning of the end...
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CN Fletcher

mwagener wrote on Sat, 11 September 2004 14:33
We are selling emotions, there are no emotions in a grid


"Recording engineers are an arrogant bunch.  
If you've spent most of your life with a few thousand dollars worth of musicians in the studio, making a decision every second and a half... and you and  they are going to have to live with it for the rest of your lives, you'll get pretty arrogant too.  It takes a certain amount of balls to do that... something around three"
Malcolm Chisholm

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