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Calibrating the Mytek 8x192 ADDA
Old 19th June 2009
  #1
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Calibrating the Mytek 8x192 ADDA

The Mytek seems to be set for -15 dBFS = +4dB OVU=1.228 VRMS) which means it's rather hot compared to what I'm used to.

I've been using Apogee and RME, so this doesn't sit well with my setup. I also find that this high level output on the Mytek tends to overload some of my analog units at unity when playing back a near full scale digital signal from the DAW.

I'm wondering what the reasoning is behind the default Mytek setting, and why I shouldn't simply re-calibrate it.. especially seing as all the input trims are rather off from the factory! ;-)

Anyone calibrated a Mytek 8x192 ADDA and care to give me some tips?

I guess I'll hook up a voltmeter for the output and use the DAW when trimming in the inputs.

But what's the reference level from the DAW, -18, -20 dBFS and at what reference voltage if I want to match my old setup? I guess I could look it up or simply experiment but I know someone here as been through it all...
Old 19th June 2009
  #2
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I'm mostly mixing records, so not sure if this will help. Although I do master about 30% of the work I'm doing these days.

-18 seems to be the default level.

I have a tonelux console, and various outboard...usual suspects for the most part. I have a DIGI 192. I have my A trims setup for -18 and my B trims setup for -14. Like you, I find in certain instances my outboard needs a lower feed, so I just switch to one or the other depending on the needs of the situation. I'm not fimiliar with the Mytek, so I don't know if this is possible. If it does have this flexibilty, then that would be the best way around this in my opinion. Have both options ready to go.

I'm glad you asked this, because i'm about to get a Lavry Blue setup for capture of the end of my chain, and now wonder what they default their cal to.
Old 19th June 2009 | Show parent
  #3
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Interested in this too. Probably going down the 8x192/RME route here in the not too distant future.
Old 19th June 2009 | Show parent
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Funny, I misread the thread title as "Celebrating the Mytek 8x192 ADDA"

I run the Mytek at default, no problems here (except with one unit I recently had on trial).

If you wanted to calibrate to lower the level, why not just connect the outs straight to the ins, play a tone through all outputs and remember the input level reading, metering ITB. Then first lower the output pots by x.xx dB (watching ITB input metering) while having the A/D on default jumper. When all are adjusted, take the A/D jumpers off default and adjust those pots to get back to the original return level ITB.

I don't see any reason to get out the voltmeter... am I missing something?
Old 20th June 2009 | Show parent
  #5
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I'm not sure how that would ensure the correct output level, or at least it will take quite some time to find it.

Mytek 8x192 ADDA manual:
http://mytekdigital.com/download_lib...r.feb_2006.pdf

Page 10
Old 20th June 2009
  #6
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Quote:
Originally Posted by Lagerfeldt ➑️
The Mytek seems to be set for -15 dBFS = +4dB OVU=1.228 VRMS) which means it's rather hot compared to what I'm used to.
......
But what's the reference level from the DAW, -18, -20 dBFS if I want to match my old setup? I guess I could look it up or simply experiment but I know someone here as been through it all...
It's early Saturday morning and I'm watching cartoons with my kids, so maybe I'm misreading you ... but doesn't -15dBFS=0VU=1.225V indicate a quieter signal than -20dBFS=0VU=1.225V?

I need coffee.

-dave
Old 20th June 2009 | Show parent
  #7
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I don't think it's 1.225 V (1.228 BTW) but OVU=0.775 V I'm used to, I believe. Correct me if I'm wrong.

I'm just looking for a simple way of getting output levels to match my other converters.
Old 20th June 2009 | Show parent
  #8
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Well, the voltage difference (.775 or 1.225/8) is whether you're thinking of 0dBU or +4dBU ... to 0VU either way

I guess from the DAC's perspective, if you're aligned to -20 = 1.228 = 0VU, aren't you cranking the signal up hotter than you would be for -15 = 1.228 = 0VU?

Tom and Jerry say hello, by the way



Sorry this is of no direct/specific assistance ... just confused by the initial description.

-dave
Old 20th June 2009 | Show parent
  #9
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I get your point and which is why I was a bit confused by the manual.

But did you read the part I wrote about OVU=0.775V?
Old 20th June 2009 | Show parent
  #10
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Yes, sorry -- I edited my post while you replied ...

Anyway, seems like you're gonna have to measure the other stuff to answer the question though .. If your Apogee and RME output a -18dBFS (or whatever level brings you to) 1.225, or 1.228 or 0.775 V = 0VU, you have found your target.

As loud as signals get through the chain these days. I personally like to hit the chain a bit softer. Might be worth experimenting with making a fundamental change in your room's cal level if you're in the midst of a converter swap.

I'm probably preaching to the choir here though, and have no answer to why there'd be any fiddliness in the cal from the factory. Looks like you have to open the box to tweak too -- Fun Fun Fun!

Good luck, Holger!

-dave
Old 20th June 2009 | Show parent
  #11
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Thanks, Dave.

Quote:
As loud as signals get through the chain these days. I personally like to hit the chain a bit softer. Might be worth experimenting with making a fundamental change in your room's cal level if you're in the midst of a converter swap.
Yes indeed.
Old 20th June 2009 | Show parent
  #12
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Quote:
Originally Posted by Lagerfeldt ➑️
I'm not sure how that would ensure the correct output level, or at least it will take quite some time to find it.

Mytek 8x192 ADDA manual:
http://mytekdigital.com/download_lib...r.feb_2006.pdf

Page 10
Can't you derrive change in output voltage from the changed dBfs readout (post the loop)?

You start with a guaranteed reference: -15dBfs= 1.228 V.

If you adjust the out pots to a tone (and measure post the shortest possible loop at the DAW input) to be, for example, 6,21 dBfs lower (than the original reading) then you are at -8,79dBfs = 1.228 V. You now have your outs calibrated to -15dBfs = 0.775 V = 0dBfs = your new 0VU.

Repeat with the input pots so that the reading is at the original value (that showed post the loop when both were on jumpers).

I'm not sure where the complication lies... If there's a flaw to my thinking, please do correct.
Old 20th June 2009 | Show parent
  #13
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🎧 15 years
Quote:
Originally Posted by 24-96 Mastering ➑️
Funny, I misread the thread title as "Celebrating the Mytek 8x192 ADDA"

I run the Mytek at default, no problems here (except with one unit I recently had on trial).

If you wanted to calibrate to lower the level, why not just connect the outs straight to the ins, play a tone through all outputs and remember the input level reading, metering ITB. Then first lower the output pots by x.xx dB (watching ITB input metering) while having the A/D on default jumper. When all are adjusted, take the A/D jumpers off default and adjust those pots to get back to the original return level ITB.

I don't see any reason to get out the voltmeter... am I missing something?

You need the voltmeter, Robin, or everything will be relative and you cannot ensure accuracy. How do you know if the adjustment pots were jangled between the factory and you? So I suggest you set the ADC side with a known analog voltage level and an accurate digital meter, then you can connect the DAC to the ADC and set it, but at that point as long as you have the analog voltmeter out might as well set the DAC as well.

A -18 dBFS = +4 dBu is a bit more conservative setting vis-a-vis analog headroom but only on the DAC side. However, on the ADC side it does not permit occasional peaks from a live recording to be captured without clipping the ADC if you are using VU meters in your console. Thus I recommend -20 dBFS = your standard reference level. For equipment that clips at exactly +24 dBu I recommend using a 0 dBu reference level = -20 dBFS sine wave. It does sound a little cleaner.

BK
Old 20th June 2009 | Show parent
  #14
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Quote:
Originally Posted by bob katz ➑️
You need the voltmeter, Robin, or everything will be relative and you cannot ensure accuracy. How do you know if the adjustment pots were jangled between the factory and you?
But there's no variable in the equation to begin with, nothing relative. The Mytek 8x192 has jumpers, for each in & out, that can fix the level to nominal, bypassing the pots completely.
That's the basis of my suggestion, as with the jumpers set to fixed level, -15dBfs is 1.228V. Which in turn, when patched back into an input (with jumper on to bypass the pot) is -15 dBfs.

That makes my converter input stage + DAW meter a very good digital volt meter imo.


This helps for voltage conversion: dB dBu dBV to volts conversion - calculator volt volts to dBu and dBV dB mW - convert dB volt calculation online attenuation loss gain ratio reference audio engineering dBFS dBVU 0 dB audio level converter - sengpielaudio Sengpiel Berlin
Old 20th June 2009 | Show parent
  #15
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Quote:
Originally Posted by 24-96 Mastering ➑️
But there's no variable in the equation to begin with, nothing relative. The Mytek 8x192 has jumpers, for each in & out, that can fix the level to nominal, bypassing the pots completely.
I see. Well, you know I was referring to a completely variable situation :-).

BK
Old 20th June 2009 | Show parent
  #16
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Quote:
Originally Posted by 24-96 Mastering ➑️
Can't you derrive change in output voltage from the changed dBfs readout (post the loop)?

You start with a guaranteed reference: -15dBfs= 1.228 V.

If you adjust the out pots to a tone (and measure post the shortest possible loop at the DAW input) to be, for example, 6,21 dBfs lower (than the original reading) then you are at -8,79dBfs = 1.228 V. You now have your outs calibrated to -15dBfs = 0.775 V = 0dBfs = your new 0VU.

Repeat with the input pots so that the reading is at the original value (that showed post the loop when both were on jumpers).

I'm not sure where the complication lies... If there's a flaw to my thinking, please do correct.
I think you are correct, though my problem is that the inputs aren't right either. So I think I need that volt meter still.
Old 20th June 2009 | Show parent
  #17
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Yes you need a digital volt meter, and then simply decide how you want to run your chain. My decision was based on the levels I want to see hitting the chain, not what the DA is doing. It can do whatever you want within reason.
Old 20th June 2009 | Show parent
  #18
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Quote:
Originally Posted by lucey ➑️
My decision was based on the levels I want to see hitting the chain, not what the DA is doing. It can do whatever you want within reason.
But assuming you have a somewhat hot signal going out and you don't want to attenuate that digitally, wouldn't it be better if the DA output level was matched with the input clipping point of the analog chain from the beginning.
Old 20th June 2009 | Show parent
  #19
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Quote:
Originally Posted by Lagerfeldt ➑️
But assuming you have a somewhat hot signal going out and you don't want to attenuate that digitally, wouldn't it be better if the DA output level was matched with the input clipping point of the analog chain from the beginning.
i have some questions for Mytek 8x192 owners,

#1. Mytek 8x192 has DC coupled outs? = works with Motu Volta ?
https://www.gearslutz.com/board/elect...lta-kills.html

#2. can you make an RMAA rightmark loop test?
http://audio.rightmark.org
and upload results like these:
RightMark Audio Analyzer test: Lynx Aurora 8 24/44 (+4 dBu)
RightMark Audio Analyzer test : Lynx Aurora 8


#3. can you make loop tests and upload results? from these source files:
https://www.gearslutz.com/board/gear-...est-redux.html

https://www.gearslutz.com/board/gear-...hout-ears.html
Old 20th June 2009 | Show parent
  #20
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Let's keep this thread on the calibration subject if possible.
Old 20th June 2009 | Show parent
  #21
Mastering
 
🎧 15 years
Quote:
Originally Posted by Lagerfeldt ➑️
But assuming you have a somewhat hot signal going out and you don't want to attenuate that digitally, wouldn't it be better if the DA output level was matched with the input clipping point of the analog chain from the beginning.
Of course. You should have the same measured analog level on both analog points and the same digital level at both digital points when they are chained. The D/A/D chain is a unity gain insert. And in between, a calibrated analog attenuator and/or gain control in your analog rack to tweak levels up or down from that calibration for, say, clipping purposes [god forbid :-)] or compensate for analog processors that are not unity.

BK
Old 20th June 2009 | Show parent
  #22
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Right, I realize I probably misunderstood Lucey's post.

I never clip the A/D, by the way. I don't see the point in doing that as opposed to clipping ITB at another stage in the chain.
Old 20th June 2009 | Show parent
  #23
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Quote:
Originally Posted by Lagerfeldt ➑️
I think you are correct, though my problem is that the inputs aren't right either. So I think I need that volt meter still.
The 8x192 inputs have jumpers for bypassing the pots / setting to standard nominal level (+4dBu=-15dBfs) too. But by all means, do use a volt meter, whatever method works best for you... I'm not on a mission here
Old 20th June 2009 | Show parent
  #24
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The problem seems to be that it isn't calibrated right with the jumpers in the factory setting. It's 0.2 dB or 0.3 off, and on channel 4 it's a massive 3 dB off.

I don't know if an elephant sat on my unit and that caused it but it looks physically okay :-) Brand new unit.
Old 20th June 2009 | Show parent
  #25
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Quote:
Originally Posted by Lagerfeldt ➑️
The problem seems to be that it isn't calibrated right with the jumpers in the factory setting. It's 0.2 dB or 0.3 off, and on channel 4 it's a massive 3 dB off.
Wow.

I've only checked pairs of twos, but they were all within 0.02 dB of each other here. OK, then you will very much need a volt meter. Or a new 8x192...

PS: did you double check that the jumpers are set to "calibrated" position? They weren't when I bought mine (bought it from a distributor, but was a demo unit, I should add)
Old 21st June 2009 | Show parent
  #26
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I can't offer any expert technical advice, but I just wanted to chime in... When I got my Mytek 8x192 it was feeding a hot signal to my daw as well. It made sense to me to feed pink/white noise (I can't remember which at the moment. Is White noise the one to use cause it's flat and pink is perceived as flat...?) Anyway, I fed some noise (hopefully the correct choice) into the line level of a pres vu meter then ran the output to the input of the converter. changed the internal jumpers to variable positions, and then I adjusted the sound so that 0 on the vu was 0 in my daw. That did it for me. That is my experience from a common sense approach... hopefully. Please, chime in otherwise.
Old 21st June 2009 | Show parent
  #27
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Quote:
Originally Posted by 24-96 Mastering ➑️
PS: did you double check that the jumpers are set to "calibrated" position? They weren't when I bought mine (bought it from a distributor, but was a demo unit, I should add)
My dealer installed the DIO card for me, so there's a chance they switched something by mistake. I'll check and report back how this all ended :-)
Old 23rd June 2009 | Show parent
  #28
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Quote:
Originally Posted by cichy ➑️
#2. can you make an RMAA rightmark loop test?

yes please !


my mytek shows noise level -98.2db
and thd 0.0015%

with loopback test at 44.1khz 24bit


what's wrong !!:?
-98dB is too high for a highend converter, problably you have verry dirty AC power line, bad calibration or worse.

please create a .html report, and also a .sav
and upload them as .zip
thanks
Old 23rd June 2009 | Show parent
  #29
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I think you should make a new post for such as comparison thread unless it's related to the calibration issue.
Old 30th June 2009 | Show parent
  #30
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So I calibrated the Mytek today, here's what I did:

I sent a 1 kHz sine tone @ -14 dBFS from my DAW and calibrated the outputs on the Mytek until it measured at 0.00 dBu on the external volt meter. I did this on all 8 outputs using a Dolby pen.

The output trim pots are quite sensitive but I managed to trim within 0.005 dB accuracy, which is more than adequate.

Now with calibrated outputs, I then output a 1 kHz sine tone @ -6 dBFS via an I/O plug-in in the DAW, coming back on an input. Each input was trimmed until the meter in the DAW showed -6 dBFS. A practical approach that I preferred.

The Mytek sounds very pleasant and detailed, and both I and Freddy of Danfield Audio took an instant liking to it. Somehow there's a lot of "sound" coming out of that converter, a bit psycho-acoustical of me to say that, I realize. I haven't even tested the A/D yet, just playing back various reference songs from the D/A, using the internal clock.

I think the RME in comparison has a bit of smearing which can be flattering on some sources. The Mytek seems more detailed but not sharp in any way and doesn't have the "smiley" sound of the Apogee. So I'm happy with my purchase!
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