Calibrating the ATR60-16

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ron-e-g

ron-e-g

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Hello all! Hope everyone had a great Thanksgiving. I know, I did.

I finally got the ATR60 tracking problem sorted out. Turned out to be a combination of Reel height, and Tension Roller height problems.. So it's off to the Electronics Calibration...screech!..stop. Now, I'm confused. I want to set the input levels at the 1 kHz +4 dbm level. So here is the thing, My M-600 has a oscillator. The console is balanced. The ATR is all balanced. My Leader Voltmeter is NOT. I have a UHF to RCA adapter, I use on the Leader for inputing a RCA connector. I also have a Male XLR to RCA adapter plus a female of the same variety. These XLR adapters have pin 2 and 3 jumper-ed. BTW, I also have a LA-80, & LA 81 at my disposal.

My Question. What would be the best way to input and output the signals on the ATR60 from the Console Oscillator and to the Leader 181A? Also, what should the meter be set to, and what should it read?

Thanks.
 
Stop right now. Not only are you confused now. You do not have the necessary test equipment to start, let alone finish an electronic calibration. I say this because you made no mention of an oscilloscope.

Read this thread: https://homerecording.com/bbs/general-discussions/analog-only/diy-alignment-calibration-286745/

Notice the test equipment.

Start with the voltmeter, You need a"True RMS volt meter" with a bandwidth of at least 100Khz and read very low i,e, 10 to 20 millivolts.

Get those sorted then come back :)
 
Actually, I do have a Tektronix 2235 (duel Trace), Isn't the Leader, a True RMS? Also... I didn't mention I have a Protek Multifunction Counter B-808, and a RF generator, plus a Fluke 77 multimeter. One more thing I have is a Fostex TT15 oscillator. I even have, a Leader 3610 Wow and Flutter Meter.:) I also have both the 15 & 30 ips calibration tapes.
 
Yes....but do you have the retro inverse spacer tool....????
 
For awhile, I dicked around (technical term) doing some bal/unbal -10/+4 level conversions between my deck and my sources for testing/calibratring....worse was trying to use my DAW for source signal.
Always ended up using my DVM to measure actual voltages, since there was always some minor discrepancy.

Anyway...I grabbed an older Loftec TS-1 off of eBay, which has both proper level options and also frequency choices (though it's pretty sensitive trying to get things at XX.000....but at worst it was like minor 1/100ths fluctuations.
I used the Loftech for a bit, and it was great and it was real cheap....then I grabbed an NTI Minirator MR1 off of eBay, and that thing is THE best little tool for calibrating levels at specific frequencies for a tape deck.
The newer MR2 ain't cheap, but I got the MR1 used for around $100, which was a good deal.

So.....you can do all that conversion stuff and make it work....but man, it's a PITA after awhile.
Ive reached for the MR1 enough times already that it's paid me back the $100. :)
 
Yea, seems as you learn, as with anything... (like woodworking) for instance,you start with a Sledge Hammer then you learn..all you need is a Finish Hammer!
I use that analogy, as I was a Carpenter for 35 Years. That said. I'd like to figure out, how to use what I currently have. I don't have a thorough understanding of such things. I used the current equipment, to calibrate my MS16 but that has RCA's along with XLR's. So I could convert to a -10 signal. Not so on the ATR. I get confused on the signal shift to the unbalanced test equipment. But..I think if I understand it correctly. I should have the Leader set to the 1 position then I would want to read the Red Scale at -2 dBm? or...like this,

SANY0088.webp OK not like that! but -2
 
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After taking a look at the XLR/RCA adapters. It appears they are not correct. They have the pin's 1&3 connected. As I read the ATR manual, it shows the Pin's 1&2 should be connected with Pin 3 Hot. Is that correct?:confused:
 
Maybe too complicated, of a question? I'll rephrase it.:) Anyone.. ever, Calibrate an ATR60-16?
 
Since you're going to use it with the M-600,the easiest way is to first set the osc. level on the M-600,(I don't remember if it is adjustable), so the meters on the M-600 read 0VU when sending the osc.to the busses.Now you can use your mixer VUs as a quasi- reference.Adjust the input levels on the 1"in the input mode until the meters on the mixer when monitoring the tape returns read 0 VU.Adjust the 1" meters in the input mode to read 0VU.Setting it up this way means when you send it 0VU from the busses,the 1" reads 0VU and the tape return metering all read 0VU- "zeros everywhere".
 
That's what I was thinking too. The osc. is assignable to the PGM buss section. At this point the level is adj. at all 16 buses. At that point the Osc..is adj.to each output to recorder by the individual buss faders. Is that what you meant? It's just, I get hung-up on totally relying on the 600's meters. I'm sure it would get me close. So..I started thinking.
I have the LA80 & 81. Both unbalanced to balanced, and balanced to unbalanced converters. If I inserted the XLR coming from the console to the recorder into the 81 thereby converting the signal to unbalanced (RCA) and taking that RCA connection to the input of the Leader AC VM. (I have the UHF to RCA) adapter installed on. At that point..I should adj. the trim on the 81's corresponding channel so the VM reads ? -6? And, or. I could verify the signal by removing the RCA from the Leader and connect the fluke 77, (red to tip and black to shield) and it should read .615 or there abouts?

Completing this thought.. I could, or should then, take the output of the recorders channel under calibration, and connect it to another channel of the 81, thereby allowing the RCA unbalanced output cable to be also measured by my Leader.? To properly measure the input and output of the ATR 60. And that channel on the 81 should also be trimmed to reflect a -6 level with the leader's Range, set to 1? and I would be reading the Green scale?SANY0088.webp
 
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ok, this is how i would do it:

1. The LMV-181A is TrueRMS meter with high bandwidth, to that is not a problem, you have the right equipment

2. 0 db on a 4dbu balanced signal means 1.22Vrms - that is the voltage that you need to measure in the RMS meter. You put it in scale "3" and measure there 1.22V, that is your reference level.

3. For Input calibration: as you are trying to measure a differential signal with the meter, one way of doing it is to use only the GND and HOT pins of the XLR connector ONLY. so it is ok to ground the COLD pin at the input of the recorder. What are you using to generate your signal ? if it is an audio generator, then it should look like this:

Generator Recorder Input
----------- -----------------

HOT (signal) -----------------> HOT on XLR input at recorder
GND ------------------> GND on XLR input at recorder
COLD on XLR input at recorder (short to GND)

So in conclusion, for the input calibration you can use one of those RCA to XLR connectors that short COLD and XLR pins, and measure 1.22VRMS on the output of the generator and that is the reference signal that you can use to calibrate input levels, meters, etc

If you are using the generator of a console that is 4dbu, then just measure with the LMV181 the voltage between HOT and GND and that should be HALF, meaning 0.614VRMS, as you are only looking at half amplitude of the signal. Or if you want you can also measure 1.22VRMS between HOT and COLD pins of the output of the console. With that adjusted, you can have your reference set for your generated signal.

4. How to measure the output: The output can be trickier as it may not be safe in all cases to short the GND and COLD pins of the output of the recorder. It depends if the output has a transformer or if it is an OpAmp, if you can post schematics for the audio card that will help. But in any case, to be safe for the output just measure the HOT pin and the COLD pin with the RMS meter. That means that GND of the meter goes to the COLD pin and the other one to HOT, leave the GND pin of the XLR on the recorder disconnected. You will be measuring 1.22VRMS as 0db or your reference. For this you may need to build your own cable or adapter to hook it up properly, not a big deal.

Hope that helps.
 
Actually, under the above conditions I think I might want to see a -10 reading on the Leader.

wkrbee Thanks for that great reply.

fganza2 Thanks once again for the very simple but descriptive response. I PM-ed you some pic's.

mdainsd Thanks for your reply...and the lashing!:laughings:
 
Sorry, no lashing intended. i wasnt familiar with your Leader meter. It physically looks like a copy of my trusty HP 3400A, but Im pretty sure they use diferent technologies. But that doesnt mater as the long as it does what you need it to!
 
No problem. It's all good.:thumbs up: I just felt like a kid, who's teacher sent him home, because he didn't have his pencil!:laughings:
 
Don't know if anyone's still following this thread. Seems like probably not, (by the lack of responses).
But, if by the off chance someone happens along. I'm going through the process of Calibrating the ATR 60. At step 7-6-4 in the manual it mentions checking the Peak LED. But no mention of how to adj. the firing of that LED. I've studied the REC/Play, and LED, and controll PCB's. Can't find any Adj. point. Anyone ever done this?

Thanks...Ron
 
hey Ron, just saw the schematics. so it is safe to jump the COLD and GND pins. that makes it easier, just use an RCA to XLR adapter that shorts those two and feed it 1.22V, to do that, put the LMV181 meter in "3" in the scale and measure the 1.22V there for the 4dbu. There must be a potentiometer to control the peak level LED. If you send the full schematics of the audio card or the part that connects to the meters, we can probably find it out in there. The ATR60 is such a great machine, it is an MS16 on steroids :)
 
U5 is an open loop amplifier, the only thing that will have an effect on the gain (thus the peak LED level) will be R310 which is the same meter adjustment. In other words you can't adjust the peak LED independently of the meter level. So it is designed to match, meaning, that you set the meter level and that should also set the LED peak properly.
 
I agree that the peak led indicator is non-adjustable. But I disagree that R301 will have any effect on its trigger point. The non-inverting feed to U5 is constant regardless of the setting of R301 as it comes off of the feed to R301, not after the wiper. The peak level is set by the resistor divider of R62 and R63. Those values give a trip point for the LED of 1.77V. That level is altered slightly (downward) by an incoming H/L input (bar over the H) which causes Q28 to conduct changing the reference voltage of U5.
 
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