1 (edited by blackcom 2018-10-09 11:44:21)

Topic: M-32 AD Analog Input Level selector

A lot of users on various forums are reporting they have to use in-line attenuators with their API 3124+ mic preamps because the output on these preamps is so hot that most AD converters will clip. Im using Adesign ATTY2Ds attenuators with mine.

However, the other day I tried bypassing the attenuator and just set the M-32 AD Analog Input Level selector to +24dB (you can choose between 13, 19 and 24dB) and guess what? The API 3124+ preamps does not clip the M-32 AD converter with this setting!

Is this somehow just too good to be true or does the Analog Input Level selector actually let you handle preamps with very hot outputs and are there any cons of doing it this way?

When reading the manual it says the level adjustment is done in the analog domain but I still dont quite understand what it does.
Anyone care to give a little further indepth on what the Analog Input Level selector is and how it actually works?

2 (edited by JRT 2018-10-11 03:26:41)

Re: M-32 AD Analog Input Level selector

blackcom wrote:

A lot of users on various forums are reporting they have to use in-line attenuators with their API 3124+ mic preamps because the output on these preamps is so hot that most AD converters will clip. Im using Adesign ATTY2Ds attenuators with mine.

However, the other day I tried bypassing the attenuator and just set the M-32 AD Analog Input Level selector to +24dB (you can choose between 13, 19 and 24dB) and guess what? The API 3124+ preamps does not clip the M-32 AD converter with this setting!

Is this somehow just too good to be true or does the Analog Input Level selector actually let you handle preamps with very hot outputs and are there any cons of doing it this way?

https://dt7v1i9vyp3mf.cloudfront.net/styles/news_large/s3/imagelibrary/G/GainStaging-02-k5HCZkbd7Ru9rk76oMPIOGXCAviwFt8..jpg

Please refer to the graphic above as you read what follows.

API 3124+ includes some LEDs on the front pannel for metering. With the front panel pad button turned off, the "nominal operating level" of 0_dB on the VU meter correlates to an output analog signal level at +4_dBu.  That also means that +20_dB on the VU meter correlates to +24_dBu output.

RME M-32 AD can be set to one of three different input levels (+24_dBu, +19_dBu, +13_dBu), and the setting choice correlates to output digital signal level at 0_dBFS. You correctly chose the setting +24_dBu input correlating to 0_dBFS output, which also means that +4_dBu input level correlates to -20_dBFS output. And as noted above, +4_dBu output from the API 3124+ correspnds to the nominal 0_dB level on the API 3124+ front panel VU meter LED when the pad is turned off.

Read some more about the subject of "Gain Staging" in the article linked below.
https://www.soundonsound.com/techniques … w-software

And a couple of articles on the subject of Level Practices (parts 1 & 2) authored by Bob Katz are linked below.
https://www.digido.com/portfolio-item/l … es-part-1/
https://www.digido.com/portfolio-item/l … es-part-2/

Re: M-32 AD Analog Input Level selector

This has to be the best reply ever! Thank you so much!

Re: M-32 AD Analog Input Level selector

Great post JRT - good educational skills!

Madiface XT, Madiface, 3x Micstasy, ADI8QS
Sequoia 14,  W7Px64, W10Px64

Re: M-32 AD Analog Input Level selector

+1

BR
Ramses
Win7 Prof, CubPro9.5, UFX+, XTC, ADI-2 Pro FS/DAC, RayDAT, ARC USB, Sonnet USB3-PRO-4PM-E

Re: M-32 AD Analog Input Level selector

The Attenuator can still be used of you like to drive the 3124 into harmonic saturation as I know they can put out more than +24dBu when in the "warm zone".  Thus the built-in attenuator on the newer 3124's...

cool

MADIface-XT+ARC / 3x HDSP MADI / ADI648
2x SSL Alphalink MADI AX
2x Multiface / 2x Digiface /2x ADI8

7 (edited by blackcom 2018-10-13 00:54:13)

Re: M-32 AD Analog Input Level selector

Randyman... wrote:

The Attenuator can still be used of you like to drive the 3124 into harmonic saturation as I know they can put out more than +24dBu when in the "warm zone".  Thus the built-in attenuator on the newer 3124's...

cool

I like to push the APIs juuust "before" it goes red. I used to go into red before and the op-amps would break a bit too ofthen and I had to return the broken one to API to be able to buy a new one from them.

Btw, I noticed my ADI-QS (not the M-32 AD) also has a Output Level Selector 4, 13, 19, 24db. What's that for, like technically?

Re: M-32 AD Analog Input Level selector

Blackcom, Potscrubber, Ramses,
Thank you for the positive feedback.

Re: M-32 AD Analog Input Level selector

Is it ok if the M-32 AD goes into "red" once in a while? Does it only affect the sound or could it potentially cause damage?

10

Re: M-32 AD Analog Input Level selector

No damage to the hardware.

Regards
Matthias Carstens
RME

Re: M-32 AD Analog Input Level selector

MC wrote:

No damage to the hardware.

Thanks, bro!