Point of oscillators in vintage mixers?

GroupDIY Audio Forum

Help Support GroupDIY Audio Forum:

Golgoth

Well-known member
Joined
Jul 24, 2015
Messages
291
Location
Paris, France
I have a stupid question and I'm sure the answer will sound obvious, but I'd rather ask than not know: what was the point of having an oscillator module on vintage mixing desks?

🤓
 
Last edited:

JohnRoberts

Well-known member
Staff member
GDIY Supporter
Moderator
Joined
Nov 30, 2006
Messages
25,121
Location
Hickory, MS
We put oscillators in console master sections to put a few different frequency tones on master tapes so upon playback the tech/engineer can check for HF head alignment.

I also included a slate tone for marking between takes. That slate used a clipped 60Hz tone. At high speed it sounded like a beep, at 1x it was dirty enough be easily audible.

These alignment tones didn't have to be very low distortion just needed decent amplitude stability.

JR
 

Gold

Well-known member
Joined
Jun 23, 2004
Messages
3,155
Location
Brooklyn
We put oscillators in console master sections to put a few different frequency tones on master tapes so upon playback the tech/engineer can check for HF head alignment.

I also included a slate tone for marking between takes. That slate used a clipped 60Hz tone. At high speed it sounded like a beep, at 1x it was dirty enough be easily
After you record tones for the record alignment you print calibrated tones on a different section of tape so that any tape machine can be calibrated to play back the tape accurately.
 

ruffrecords

Well-known member
GDIY Supporter
Joined
Nov 10, 2006
Messages
15,136
Location
Norfolk - UK
Back in the 70s Neve sent me on a studio engineer course run by the APRS. One day we visited a well known London studio (courtesy of Clive Green of CADAC). They had some session musicians in and they were showing us how they tracked. We were listening through huge CADAC monitors the size of wardrobes. We were shown how they added alignment tones to tape using the built in oscillator when somebody somehow managed to route a 15KHz oscillator tone to the monitors. There was a very short screech before the operator quickly flicked the oscillator off. We thought no more of it until it came to record the next take when we all noticed a distinct lack of top end. It turned out the CADAC monitors had fuses in series with all the drive usints and the HF fuses had been blown on both of them.

Cheers

ian
 

pucho812

Well-known member
Joined
Oct 4, 2004
Messages
13,696
Location
third stone from the sun
Back in the 70s Neve sent me on a studio engineer course run by the APRS. One day we visited a well known London studio (courtesy of Clive Green of CADAC). They had some session musicians in and they were showing us how they tracked. We were listening through huge CADAC monitors the size of wardrobes. We were shown how they added alignment tones to tape using the built in oscillator when somebody somehow managed to route a 15KHz oscillator tone to the monitors. There was a very short screech before the operator quickly flicked the oscillator off. We thought no more of it until it came to record the next take when we all noticed a distinct lack of top end. It turned out the CADAC monitors had fuses in series with all the drive usints and the HF fuses had been blown on both of them.

Cheers

ian
Better the fuses than the hf tweeters, drivers. My first tech and studio job when I came to Los Angeles was a place that did not fuse speakers. The owner felt they ruined the sonic. Boss man says no fuses, ok no fuses. Sure enough we had several times speakers were ruined and components needed replacement vs a simple let’s change out the fuse.
 

KA-Electonics.com

Active member
White Market Member
Joined
Dec 13, 2022
Messages
35
Location
Dallas, Texas
As Gold points out tape calibration.

An important safety tip to remember is always place the "record pad" - the place on the master you use for record calibration - at the tail.
Why?
Because if you place it at the head you risk over-running it and erasing the first song. (Or more.)

I knew a tech once doing record calibration with the record pad at the head...
As he was printing tone doing record cal the phone rang...
He answered it, the unattended machine ran past the leader in-between sections, and he erased the first few minutes of the multitrack master.
He was fired on the spot.
Avoiding print-through is another good reason for [email protected]

If the console is used in a broadcast environment tone is frequently run continuously during idle periods to maintain confidence in the transmission path and prevent silence alarms from triggering.
 
Last edited:

JohnRoberts

Well-known member
Staff member
GDIY Supporter
Moderator
Joined
Nov 30, 2006
Messages
25,121
Location
Hickory, MS
Back in the 70s Neve sent me on a studio engineer course run by the APRS. One day we visited a well known London studio (courtesy of Clive Green of CADAC). They had some session musicians in and they were showing us how they tracked. We were listening through huge CADAC monitors the size of wardrobes. We were shown how they added alignment tones to tape using the built in oscillator when somebody somehow managed to route a 15KHz oscillator tone to the monitors. There was a very short screech before the operator quickly flicked the oscillator off. We thought no more of it until it came to record the next take when we all noticed a distinct lack of top end. It turned out the CADAC monitors had fuses in series with all the drive usints and the HF fuses had been blown on both of them.

Cheers

ian
Back when I was still spending time in recording studio control rooms, for chuckles I would sometimes stand in the back of the room and whistle softly at 10kHz+, then wait to see how long it took for somebody to notice. ;)

JR
 

pucho812

Well-known member
Joined
Oct 4, 2004
Messages
13,696
Location
third stone from the sun
As Gold points out tape calibration.

An important safety tip to remember is always place the "record pad" - the place on the master you use for record calibration - at the tail.
Why?
Because if you place it at the head you risk over-running it and erasing the first song. (Or more.)

I knew a tech once doing record calibration with the record pad at the head...
As he was printing tone doing record cal the phone rang...
He answered it, the unattended machine ran past the leader in-between sections, and he erased the first few minutes of the multitrack master.
He was fired on the spot.
Avoiding print-through is another good reason for [email protected]

If the console is used in a broadcast environment tone is frequently run continuously during idle periods to maintain confidence in the transmission path and prevent silence alarms from triggering.
I always splice leader tape between playback and record pads as well as after the record pad before useable tape.
It sounds different and can easily let a person know when they went too far forward and to rewind back to continue alignment.

I also use the leader tape with arrows and write on it in sharpie. If a person screws up after all that. Then they really were not paying attention
 

fazer

Well-known member
Joined
Sep 10, 2007
Messages
1,829
Location
Elizabeth
All of the above. After years in the studio seeing alignment over running into the program recording , put the record pad at the end after the program. It’s such an easy prevention. Thing is you might want to leave an extra 2 mins after the tones and move it to the end of the last song after it is recorded in the basic tracking session. That way you leave all the tape at the end for the last song so as not to run into a leader when doing the initial recording.

Hey puncho are you splicing 2” or just using it for analog sound quality and then into protools?
 

pucho812

Well-known member
Joined
Oct 4, 2004
Messages
13,696
Location
third stone from the sun
All of the above. After years in the studio seeing alignment over running into the program recording , put the record pad at the end after the program. It’s such an easy prevention. Thing is you might want to leave an extra 2 mins after the tones and move it to the end of the last song after it is recorded in the basic tracking session. That way you leave all the tape at the end for the last song so as not to run into a leader when doing the initial recording.

Hey puncho are you splicing 2” or just using it for analog sound quality and then into protools?
Yes I am splicing 2” but not as much as I used to. If the client wants it, we’ll you know the deal.
 

pucho812

Well-known member
Joined
Oct 4, 2004
Messages
13,696
Location
third stone from the sun
Back when I was still spending time in recording studio control rooms, for chuckles I would sometimes stand in the back of the room and whistle softly at 10kHz+, then wait to see how long it took for somebody to notice. ;)

JR
Years ago was in the studio with a client who was the poster boy for how not to treat staff. He was a complete jerk. So deciding I had enough of him treating staff as such so I casually turned on the oscillator at the highest frequency it would go, 16k. I put in earplugs as it was a tracking date. With in minutes his attitude changed from yelling at people to I got to get out of here. Session was soon postponed to a later date.
 
Last edited:

Dualflip

Electronic monk
Joined
Nov 15, 2008
Messages
1,885
Location
Mexico City, MX
Years ago was in the studio with a client who was the poster boy for how not to treat staff. He was a complete jerk. So deciding I had enough of him treating staff as such do I casually turned on the oscillator at the highest frequency it would go, 16k. I put in earplugs as it was a tracking date. With in minutes his attitude changed from yelling at people to I got to get out of here. Session was soon postponed to a later date.
You basically implemented the first studio crowd control ADS.
 

pucho812

Well-known member
Joined
Oct 4, 2004
Messages
13,696
Location
third stone from the sun
You basically implemented the first studio crowd control ADS.
Well, in the old days of crt monitors, was in school and talking to the studio tech basically said there is something wrong in studio”insert letter”. He asked what I was talking about and I explained how it felt weird in there. He laughed and said turn off the monitor. When it doesn’t have signal but is on, it’s black screen, bring on emits high frequency which is most likely what you noticed and way it was weird. He was not wrong.
 
Last edited:

Dualflip

Electronic monk
Joined
Nov 15, 2008
Messages
1,885
Location
Mexico City, MX
Well, I’m the old days of crt monitors, was in school and talking to the studio tech basically said there is something wrong in studio”insert letter”. He asked what I was talking about and I explained how it felt weird in there. He laughed and said turn off the monitor. When it doesn’t have signal but is on, it’s black screen, bring on emits high frequency which is most likely what you noticed and way it was weird. He was not wrong.
Yes, I can very much remember the unmistakable high-pitched sound of a CRT TV.
 

Latest posts

Top