Your Home Studio and the Calibration of it?

[mdainsd]

Ok, just a calibration question for you analog type home recording enthusiasts.

The basic question is:

Do you or Don't you?

More detailed questions:

Do you calibrate your tape machines at the intervals called for by the manufacturer?

Do you have your test equipment calibrated, scopes, meters etc?

Have you calibrated your control room, mainly monitors using a spectrum analyzer?

Just curious mainly.

Thanks!

 

[A Reel Person]

Ok, just a calibration question for you analog type home recording enthusiasts.

The basic question is:

Do you or Don't you?
Only by necessity. My personal use has gone down dramatically & in the turnaround I've been calibrating recorders as I've been selling them off. I feel better and more ethical doing that & I know the unit is going to the new owner in peak condition and trouble free. Occasionally I'll do a calibration for myself & keep something, but it's a fluid situation and TBD.

More detailed questions:

Do you calibrate your tape machines at the intervals called for by the manufacturer?
No.

Do you have your test equipment calibrated, scopes, meters etc?
No. The recorders begin markedly off-cal, and when done dramatically on-cal, and realistically it's not rocket science. IOW, the proof is in the pudding & close enough not to sweat the small stuff.

Have you calibrated your control room, mainly monitors using a spectrum analyzer?
Yes. You're one of the few people on this board to have shown any recognition of how important this is.

Just curious mainly.

Thanks!
YW!
(See: off-tape response after calibration)

 

[miroslav]

Yes....I calibrate my audio gear as needed....recorders, monitors, console, etc.....and yes, I re-check it occasionally, some things more, some less, but I'm not fanatical about it since I don't use it heavily like a commercial studio might, so it's not going to go out of calibration as fast, and I'm the only one using it, so I know when it's right or wrong.
I'm always checking basic operational levels as I go from session to session....but that's like second nature.

I have all the necessary test equipment...scope, several multi-meters, audio test frequency generators and signal multi-level generator, W&F meter, tape tension meter, test tapes....etc.

 

[Beck]

More detailed questions:

1. Do you calibrate your tape machines at the intervals called for by the manufacturer?

2. Do you have your test equipment calibrated, scopes, meters etc?

3. Have you calibrated your control room, mainly monitors using a spectrum analyzer?

Just curious mainly.

Thanks!

1. Yes
2. Yes
3. No, not with a spectrum analyzer because I don't believe in EQing the monitors, but my control room is carefully setup with sound absorbent and diffusion materials. I use a sound level meter, but that's about it.

 

[mdainsd]

Interesting replies. Need more samples.....

Beck, why may I ask do you not believe in EQing the monitors?

 

[LouI]

TASCAM 234 stuck in fast forward... As soon as a tape goes in it goes in FFd?? HELP!

hi, i'm new here.

I have a Tascam 234 and as soon as you put a tape in the drive it goes right into fast forward??????? This is all it will do and you can't stop it no matter what. Well if you push and hold STOP or PLAY it stops but as soon as you release your finger its goes right back into FF???.

It has new idler tires/Control Belt/Pinch roller and capstan belt.

I hope you can help me.
LouI

 

[ecc83]

In the heady days of tape and Dolby A, calibration was vital.

The absolute levels fed to the Dolby equipment had to be spot on so it was usual to include a few spot frequencies at a specified level so that tapes from other studios/machines coming in for mixing, mastering or cutting could be check and set up correctly.

Then, a studio would buy batches of tape and each would vary a tiny bit in sensitivity so the tape ops job would be to check and mark them up. (Tape Ops were fairly low down the food chain AFAIK so they would not be trusted with the alignment of a 24track 3M!).

Do peeps use Dolby these days? If not, absolute levels are not so critical.

I too am against room EQ as such. There have been many arguments for and against but just one is.."So, the RTA shows an 8dB crevasse at 62Hz (say). Where are you going to find the sort of power needed to correct that!"

Calibrating the nearfileds with a modest (C weighted) SPL meter and pink noise? ALL for that!

Dave.

 

[miroslav]

Do peeps use Dolby these days? If not, absolute levels are not so critical.

Well...I don't know if non-use of any Dolby really removes the need for calibration and awareness of level structure.

If peeps calibrated their gear/room/signal chains....the understanding of gain structure and better level balance would be easier and the results would be more consistent.
Sure, digital lets your do whatever you want with levels...but it's exactly that lack of absolute reference and any adherence to it that leaves so many with level issues both going in and coming out of DAWs.

Yes, back in tape/analog-only days everyone just did it, and even the early home-rec tape guys learned quickly about it....but these days, the peeps don't even think about it or realize the value of it.
It's safe to say that almost everyone that came up from the tape/analog-only world and transitioned over to the DAW or some hybrid combination, most likely has had little trouble with level structure on their digital side because they probably still follow those basic tape/analog calibration procedures and principals.

 

[A Reel Person]

...

hi, i'm new here.

I have a Tascam 234 and as soon as you put a tape in the drive it goes right into fast forward??????? This is all it will do and you can't stop it no matter what. Well if you push and hold STOP or PLAY it stops but as soon as you release your finger its goes right back into FF???.

It has new idler tires/Control Belt/Pinch roller and capstan belt.

I hope you can help me.
LouI

It's impossible to tell from afar, but as I've done the 234 belts/tires refurbishment & made a few mistakes along the way,... my inclination is to suspect that in reassembly the tech got a couple connectors swapped and plugged into the wrong sockets,...

i.e., the reel motor connector may be plugged into the connector that "homes" and controls the up/down motion of the heads. Most of the internal connectors are color coded, number of pins-specific, and cable dressed for certain length, but these (reel motor and head-carriage motor) two leads are the same color and relatively the same length wire,... and therefore can be confused and swapped.

What happens, first and foremost when the unit is initialized, is the mechanism tries to lower the heads into the down-most "home" position, before proceeding. If it does not sense the head is all the way down, the motor will keep driving endlessly. So, I suspect in your case the two connectors are inadvertently swapped and this constant energy to drive the heads down is being fed to the "reel" motor. (tape hub motor, whatever you'd like to call it).

That's a best guess estimate from afar, sight unseen. Good luck!

 

[ecc83]

"Well...I don't know if non-use of any Dolby really removes the need for calibration and awareness of level structure."

Sorry M! Did not mean to imply that you are sloppy!
The point about Dolby is that even a dB or two up or down will(did) result in a frequency imbalance. Whereas if you send your mate a tape and he plays it back 3dB under your level it will just be quieter.

I completely agree that folks should always keep levels consistent, if nothing else it show a degree of "professionalism".

Not so sure I agree about the old tape guys coming into digital "unscathed"? Top studio techs no doubt but there are STILL many people out there that do not grasp the "neg 18" concept!

Dave.

 

[miroslav]

Not so sure I agree about the old tape guys coming into digital "unscathed"? Top studio techs no doubt but there are STILL many people out there that do not grasp the "neg 18" concept!

There's still a lot of debate about -18dBFS.
I've had my analog front end doing exactly what it should and what I wanted it to do...with an eye on reference levels and calibration.....and I could still hit the converters hotter than -18dBFS.
Sure, that's the absolute "safe" target....but the audio will not automatically suffer if your hitting -12 or even -8 dBFS at times.

Point was....if you have your tape/analog stuff calibrated the "old school" way....there's little chance the digital side will suffer in any way whatsoever without you having to make any adjustments.
Trouble is, the peeps who never did or never understood old-school analog calibration...are often all over the place in the digital world, and they follow little if any level structure because digital allows them not to....but that constantly causes issues for a lot of people when their audio just doesn't seem to "gel" as desired...not to mention the ones who try to balance things by eye in the DAW.

 

[ecc83]

Not quite sure what you mean about "still a lot of debate about -18dBFS"?

Peeps WILL debate the arse off anything audio in forums! No, I am simply referring to neg 18 as a calibration point that equates with 0VU and that anything above that should be viewed as entering into what WAS the old analogue headroom region.

Of course for "prosumer" electronics, analogue and digital, the equipment is "calibrated" all over the shop as far as levels are concerned. It is hard, sometimes impossible to find out what signal input voltage gives you -18 or any other measure on many AIs!


Dave.

 

[miroslav]

Not quite sure what you mean about "still a lot of debate about -18dBFS"?

The debate that recording with higher average levels is not good....since that coresponds to 0VU, and going higher there is most likely going to be distortion/overload on the analog side.

 

[ecc83]

The debate that recording with higher average levels is not good....since that coresponds to 0VU, and going higher there is most likely going to be distortion/overload on the analog side.

Ah! Well that would be a failing of design. No system should produce any significant distortion at even -0.1dBFS!

The highest level most A/D chips can (must!) accept is about 5volts peak to peak and so it is hardly rocket science to produce an analogue circuit that can produce a miserly 2V rms at practically zero distortion. (NE5532s have been doing it for 30 years!).

Dave.

 

[miroslav]

No...not on the digital side....on the analog side.
The logic is....if you're hitting your converters at stuff higher than say -12/-10 dBFS, your analog front end is probably distorting, or working at its outer most limits.
My point was that I've been able to hit up to -6dBFS or higher...and my analog front end was doing fine.

That said...I get the logic behind the lower levels at the converter, since it will automatically put the analog front end in a more "safe" operating range, but I find that's more relative to the many cheap all-in-one analog/digital interface boxes, but not really the case with higher-end individual analog components that can churn out quite high levels without even breaking a sweat.

 

[ecc83]

No...not on the digital side....on the analog side.
The logic is....if you're hitting your converters at stuff higher than say -12/-10 dBFS, your analog front end is probably distorting, or working at its outer most limits.
My point was that I've been able to hit up to -6dBFS or higher...and my analog front end was doing fine.

That said...I get the logic behind the lower levels at the converter, since it will automatically put the analog front end in a more "safe" operating range, but I find that's more relative to the many cheap all-in-one analog/digital interface boxes, but not really the case with higher-end individual analog components that can churn out quite high levels without even breaking a sweat.

Morning Miro' I think we are on different buses with the wrong map here!

My point was that A/D converters only need around 2V (+6dBV, +8dBu) to produce 0dBFS. So even the meanest, cheapest AI mic/line/instru' pre should be able to drive that with minimal distortion.

Yes, "pro" converters have input capabilities of some +22dBu for 0dBFS so, in order to keep the converter happy they would have to have a large net internal attenuation so that all other analogue kit, mixers, outboard etc, can run at pro, +4dBu levels.

All the noob needs to know is "Run at 24 bits (44.1kHz) and keep average levels at -18dBFS". It would be nice if all AI mnfctrs told us how many decibabble "u's" we needed to achieve neg 18 but few do!

Dave.

 

[miroslav]

"Run at 24 bits (44.1kHz) and keep average levels at -18dBFS".

Right....but that has become some sort of "rule"....and I've seen people argue that not following ^^^^ you will have problems.
All I'm saying is....that isn't necessarily so. Not keeping things it -18dBFS isn't automatically a bad thing.

That's the debate I was referring to.

 

[ecc83]

Right....but that has become some sort of "rule"....and I've seen people argue that not following ^^^^ you will have problems.
All I'm saying is....that isn't necessarily so. Not keeping things it -18dBFS isn't automatically a bad thing.

That's the debate I was referring to.

No, not a bad thing but I cannot see a lot of merit in departing from it? -18dBFS is digital "operating level" tho' some strange folks use -20 I believe?

You can set a tape machine for any dBu value out within reason for reference flux but unless you have some odd bit of gear that needs strange levels I can't see the point? I would rather mod the oddity with an amp or attenuator to bring it in line with the +4dBu paradigm.

Dave.