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dbfs output on preamp not matching up to to DAW input level, why?
Old 26th December 2019
  #1
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dbfs output on preamp not matching up to to DAW input level, why?

I have the focusrite ISA 2 preamp going into a Clarett 4 and on the front panel of the ISA there is metering in dbfs. The problem is that when this meter is just barely peaking at -18dbfs, in my DAW I am already clipping (0dbfs). Does anyone have any ideas as to why this could be happening?
Old 26th December 2019
  #2
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Claret set to mic input rather than line input?
Old 31st December 2019 | Show parent
  #3
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Quote:
Originally Posted by zilla_studios View Post
Claret set to mic input rather than line input?
For the 4 front inputs, the Clarett allows you to change between Line input and Instrument input only. On the Clarett 4, there are 4 additional Line level inputs on the back which is what I am using as the input from my ISA 2. So basically the path is

Microphone > ISA 2 > Clarett Line input on back

Now there is a meter calibration knob at the back which lets you calibrate the meter somewhat from 16dbu = 0dbfs to 24dbu =0dbfs but it seems that no matter where I set this, the meter on the ISA 2 is too low. When I am getting a good level in my DAW, the Dbfs meter on the ISA 2 is pretty much around -42dbfs.

Focusrite have told me to calibrate the meter which I did but as I just mentioned,the calibration knob does little to change the metering on the ISA 2. something, somewhere is wrong. Anyone here have ideas while I wait for support to get back to me?
Old 31st December 2019
  #4
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To be more specific, even when my Meter Calibration knob is set fully anti-clockwise (0dbfs = 16dbu) my Clarett is getting a much louder signal that what the ISA 2 is showing on the meter. In this position my ISA meter barely peaks at -12dbfs and the signal is clipping in my DAW. How can this be?
Old 31st December 2019
  #5
If you check reviews of the ISA two on Sweetwater the only complaint that comes up over and over is that the meter is completely fine with inaccurate. When I found the calibration knob on the back of mine I thought "these idiots just didn't read the manual and didn't know they could adjust the meter calibration.". However that didn't help me at all. There's no setting that matches the peak point of my Orion 32+ so I'm just relying on it. It still sounds great and has plenty of headroom.
Old 31st December 2019
  #6
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Brian M. Boykin's Avatar
 
🎧 15 years
You need to check levels. Run a 1k tone into the line input of the Focusrite and set the meter to read -18dbfs. Now measure the output on the Focusrite in RMS. It should read 1.228v. If it does it’s not the Focusrite. My MOTU input and output preamps are trimable via the software. Not sure if the Clarette has this function but if so it may not be passing the audio on at unity gain. It may be boosting the signal going to DAW. That would explain it. You’d know this because the if the 1k tone is set to 1.228vRMS going into the Clarette the DAW should meter out at -18dbfs. Find where the issue is and then see if it’s fixable. Most people don’t think to check the meters in their DAW to see if they’re accurate. They just assume.
Old 1st January 2020 | Show parent
  #7
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Quote:
Originally Posted by Brian M. Boykin View Post
You need to check levels. Run a 1k tone into the line input of the Focusrite and set the meter to read -18dbfs. Now measure the output on the Focusrite in RMS. It should read 1.228v.
Ok but I have never done this before. Would I achieve this by creating a test tone in my DAW and sending it to an output on my interface then connecting that output to an input?
Old 1st January 2020 | Show parent
  #8
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Quote:
Originally Posted by D_T_Music View Post
If you check reviews of the ISA two on Sweetwater the only complaint that comes up over and over is that the meter is completely fine with inaccurate. When I found the calibration knob on the back of mine I thought "these idiots just didn't read the manual and didn't know they could adjust the meter calibration.". However that didn't help me at all. There's no setting that matches the peak point of my Orion 32+ so I'm just relying on it. It still sounds great and has plenty of headroom.
Yeah, I went and read the review. This:

"0db" on the meters is absolutely nowhere near 0db on the digital scale, the internal bias is so far off that the meters are unusable. Even accounting for the adjustment knob on the back turned all the way up, the meters internal bias is still set WAY too low. If you're near clipping on this unit's meters, everything else in your chain is being clipped to hell and back. 0db on this unit is like 15db in your DAW, straight distortion.

ok but lets hold on a second here. Couldn't this be due to added gain somewhere else in the chain like on the inputs of your interface or your mixing desk? For example, it says on the Clarett spec sheet that there is "fixed added gain" on the back inputs of the Clarett 4 (the front inputs are mic/line inputs with variable gain). This means that when you use the line inputs on the back of my interface, gain is added at the input. I don't know how much gain is added but could this be the case here?

Last edited by attaboy_jhb; 1st January 2020 at 03:01 PM..
Old 1st January 2020 | Show parent
  #9
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Brian M. Boykin's Avatar
 
🎧 15 years
Quote:
Originally Posted by attaboy_jhb View Post
ok but lets hold on a second here. Couldn't this be due to added gain somewhere else in the chain like on the inputs of your interface or your mixing desk? For example, it says on the Clarett spec sheet that there is "fixed added gain" on the back inputs of the Clarett 4 (the front inputs are mic/line inputs with variable gain). This means that when you use the line inputs on the back of my interface, gain is added at the input. I don't know how much gain is added but could this be the case here?
This is my point. So to find out you need to measure levels all along the way. You can google “tone generator” and pick one. Set it for a 1khz tone. Feed the tone into the focusrite. It doesn’t matter what level you feed it in at but a decent enough level you don’t have to crank the Focusrite to get the meters to read -18dbfs. Measure the 1khz tone with a multimeter at the line output of the focusrite when the meter is reading -18dbfs. It should read 1.228vrms. (This reference changes with who you talk to. Some use -15dbfs and others -20dbfs. It’s all about the headroom you want and even type of music your recording. -18dbfs was referenced but the OP so I ran with it. Subsequently, This is probably why Focusrite gives you the ability to adjust them.) Anyway, now feed your 1.228vrms 1khz tone to the Clarette. Then arm a track in your DAW. It should peak at -18dbfs unless the Clarette is boosting or cutting the gain upon entry or the DAW is referenced different. Your calibrating 3 different pieces of gear here and all three can have different preprogrammed references to the analog world. Thus the reason for being able to trim input and output stages.
Old 1st January 2020 | Show parent
  #10
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i think your issues are in the analog domain:

the max. output of the isa preamp is at +24dBu, so 6dB higher that the clarett's max. input at +18dBu.

use a 6dB line attenuator and things should be fine...
Old 1st January 2020 | Show parent
  #11
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Quote:
Originally Posted by Brian M. Boykin View Post
This is my point. So to find out you need to measure levels all along the way. You can google “tone generator” and pick one. Set it for a 1khz tone. Feed the tone into the focusrite. It doesn’t matter what level you feed it in at but a decent enough level you don’t have to crank the Focusrite to get the meters to read -18dbfs. Measure the 1khz tone with a multimeter at the line output of the focusrite when the meter is reading -18dbfs. It should read 1.228vrms. (This reference changes with who you talk to. Some use -15dbfs and others -20dbfs. It’s all about the headroom you want and even type of music your recording. -18dbfs was referenced but the OP so I ran with it. Subsequently, This is probably why Focusrite gives you the ability to adjust them.) Anyway, now feed your 1.228vrms 1khz tone to the Clarette. Then arm a track in your DAW. It should peak at -18dbfs unless the Clarette is boosting or cutting the gain upon entry or the DAW is referenced different. Your calibrating 3 different pieces of gear here and all three can have different preprogrammed references to the analog world. Thus the reason for being able to trim input and output stages.
I dont have a multimeter. Can you not test this without one?
Old 1st January 2020 | Show parent
  #12
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Quote:
Originally Posted by deedeeyeah View Post
i think your issues are in the analog domain:

the max. output of the isa preamp is at +24dBu, so 6dB higher that the clarett's max. input at +18dBu.

use a 6dB line attenuator and things should be fine...
Does the variation in max output/input between the two units have the ability to change the level of the incoming signal? How is this possible?
Old 1st January 2020 | Show parent
  #13
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nosebleedaudio's Avatar
 
🎧 15 years
Quote:
Originally Posted by deedeeyeah View Post
i think your issues are in the analog domain:

the max. output of the isa preamp is at +24dBu, so 6dB higher that the clarett's max. input at +18dBu.

use a 6dB line attenuator and things should be fine...
The specs I saw was +26dB Max input @ minimum gain (Channels 1-4)..
Old 1st January 2020 | Show parent
  #14
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Quote:
Originally Posted by nosebleedaudio View Post
The specs I saw was +26dB Max input @ minimum gain (Channels 1-4)..
if so, even worse...

(afaik, we're talking about the isa2 which got 2 inputs; not sure about specs - the manual should contain all info though)



Quote:
Originally Posted by camomiletea View Post
Does the variation in max output/input between the two units have the ability to change the level of the incoming signal? How is this possible?
you got two units which are designed to operate at different max. analog i/o levels before clipping so you risk overdriving the item with the lower input capacity: that's why i recommend level matching them in the analog domain - you then just calibrate to whatever digital reference you prefer working at.
Old 1st January 2020
  #15
What about the front inputs - same issue?
Old 1st January 2020 | Show parent
  #16
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Quote:
Originally Posted by deedeeyeah View Post
if so, even worse...




What??? +26dB is HIGHER than +18dB..BETTER..
Old 1st January 2020 | Show parent
  #17
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Quote:
Originally Posted by nosebleedaudio View Post
What??? +26dB is HIGHER than +18dB..BETTER..
you got me wrong: for the poster seeking to match levels between his items, a higher difference imo is worse.

(and no, higher output does not necessarily mean better audio quality)
Old 1st January 2020 | Show parent
  #18
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Quote:
Originally Posted by deedeeyeah View Post
you got me wrong: for the poster seeking to match levels between his items, a higher difference imo is worse.

(and no, higher output does not necessarily mean better audio quality)
Now your ADDING to what I said...BAD...
Your looking at this wrong..
I would prefer a HIGHER input level NOT lower...regardless of anything else..
Old 1st January 2020 | Show parent
  #19
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Quote:
Originally Posted by nosebleedaudio View Post
Now your ADDING to what I said...BAD...
Your looking at this wrong..
I would prefer a HIGHER input level NOT lower...regardless of anything else..
?!

well, i guess there's no way around the specs of the gear: if preamp has hotter output than the a/d converter's max. input capacity (interface in this case), i stand firm that it's wise to LOWER the level of the preamp output by inserting a line level pad, to prevent the inputs of the interface from clipping...


...or to replace the interface.


EDIT: me bad - i thought you were referring to the isa outputs being even higher to what i read...

Last edited by deedeeyeah; 1st January 2020 at 09:08 PM.. Reason: EDITED
Old 1st January 2020 | Show parent
  #20
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🎧 5 years
Quote:
Originally Posted by omega75 View Post
What about the front inputs - same issue?
No, on the front it is fine so long as I keep the gain all the way down. But isnt that because when you go through the front inputs and the gain is all the way down you are actually attenuating?
Old 1st January 2020 | Show parent
  #21
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Quote:
Originally Posted by deedeeyeah View Post
?!

well, i guess there's no way around the specs of the gear: if preamp has hotter output than the a/d converter's max. input capacity (interface in this case), i stand firm that it's wise to LOWER the level of the preamp output by inserting a line level pad, to prevent the inputs of the interface from clipping...


...or to replace the interface.
Whats the difference between line attenuator and using the variable gain inputs on the front of the clarett?
Old 1st January 2020 | Show parent
  #22
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Quote:
Originally Posted by nosebleedaudio View Post
The specs I saw was +26dB Max input @ minimum gain (Channels 1-4)..
That is input via the front of the unit. The back inputs 5 -7 are 18dbu max which is what I bought the clarett 4 for. I wanted a fixed line in from external pres but I had no idea there would be a problem going into line 5 - 7. In fact i thought it would be better because fron what i understood, the back inputs dont pass through the preamps circuitry and i thought that this would be better as the signal would go straight to the converters inside the Clarett.
Old 1st January 2020 | Show parent
  #23
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Quote:
Originally Posted by camomiletea View Post
Whats the difference between line attenuator and using the variable gain inputs on the front of the clarett?
basically nothing but if the clarett doesn't allow for high enough input levels even on the lowest setting, then you might still overdrive the input stage and clip the converters - of course you could also lower the input gain on the isa but reasults (soundwise) might vary a bit...

[speaking of level matching: one of my studios has all but analog gear (except for efx devices) and EVERYTHING is matched (and needs occasional re-adjustment) via studer line level converters - quite an expensive 'hobby' but it makes live so much easier not to have to think about levels when patching across gear! otherwise, max. i/o capacity varies a lot: from +15dBu to +27dBu in my case)
Old 1st January 2020 | Show parent
  #24
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Quote:
Originally Posted by deedeeyeah View Post
basically nothing but if the clarett doesn't allow for high enough input levels even on the lowest setting, then you might still overdrive the input stage and clip the converters - of course you could also lower the input gain on the isa but reasults (soundwise) might vary a bit...

[speaking of level matching: one of my studios has all but analog gear (except for efx devices) and EVERYTHING is matched (and needs occasional re-adjustment) via studer line level converters - quite an expensive 'hobby' but it makes live so much easier not to have to think about levels when patching across gear! otherwise, max. i/o capacity varies a lot: from +15dBu to +27dBu in my case)
But from what nosebleed said, the front inputs do allow higher input levels right?
Old 1st January 2020 | Show parent
  #25
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Quote:
Originally Posted by camomiletea View Post
But from what nosebleed said, the front inputs do allow higher input levels right?
yes, that would do the trick (i got him wrong and hence edited one of my posts: i thought he was referring to the isa even having higher output) - you can feed the +24dBu outputs of the isa into the clarett's variable level front inputs which are capable of accepting levels of up to +26dBu before clipping (potential 'underpowering' an input does no harm).


the only minor issue is that it's not a fixed level solution which you were originally looking for - for this, you'd use attenuators and stick them before the clarett's rear panel inputs.

sorry for the confusion!
Old 1st January 2020
  #26
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I would guess the problem might be your meter is set to track the signal at INPUT.

That would mean it's not accounting for the actual preamp or EQ gain.

I seem to remember those things having a multi-option meter, make sure it's metering what's LEAVING the machine, not what's appearing at the input.

Oh...and turn off "Fart" "Air" whatever the hell they call that crapola.
Old 1st January 2020 | Show parent
  #27
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Brian M. Boykin's Avatar
 
🎧 15 years
Quote:
Originally Posted by camomiletea View Post
I dont have a multimeter. Can you not test this without one?
I would get one. There are so many uses for one with this being one of them. I’ll also suggest reading up on the different scales for dB. There’s a great thread on the newbie forum. I reread it often just to freshen up.

At the end of the day you have an analog signal coming from the Focusrite and Focusrite has chosen to reference that level in dBFS. I’m assuming to make it easier to match levels to a DAW. Idk. But really, you don’t want to be clipping any of the stages and especially the digital stage because that results in clicks and pops. I track through Symetrix SX202’s and they only have a clip light. I use my ears to find the sweet spot of the preamp and source material. As long as I have a good clean signal being recorded with peaks around -6dBfs I’m happy. I’m surprised an old timer hasn’t chimed in yet and said to just use your ears for setting levels and gain stages. Every piece of gear will have a sweet spot where they just sound pleasing to the ear. The art in all this is finding those sweet spots and gain staging between gear to get that sonic sweetness. Levels are important for telling you where you are on the field like yard markers, even better if their all referenced the same, but your ears do the real work.
Old 1st January 2020
  #28
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And for the record, I’m with nosebleed, I want the highest analog headroom I can get. I’ll adjust my dBFS scale around it.
Old 1st January 2020 | Show parent
  #29
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Quote:
Originally Posted by Brian M. Boykin View Post
I would get one. There are so many uses for one with this being one of them. I’ll also suggest reading up on the different scales for dB. There’s a great thread on the newbie forum. I reread it often just to freshen up.

At the end of the day you have an analog signal coming from the Focusrite and Focusrite has chosen to reference that level in dBFS. I’m assuming to make it easier to match levels to a DAW. Idk. But really, you don’t want to be clipping any of the stages and especially the digital stage because that results in clicks and pops. I track through Symetrix SX202’s and they only have a clip light. I use my ears to find the sweet spot of the preamp and source material. As long as I have a good clean signal being recorded with peaks around -6dBfs I’m happy. I’m surprised an old timer hasn’t chimed in yet and said to just use your ears for setting levels and gain stages. Every piece of gear will have a sweet spot where they just sound pleasing to the ear. The art in all this is finding those sweet spots and gain staging between gear to get that sonic sweetness. Levels are important for telling you where you are on the field like yard markers, even better if their all referenced the same, but your ears do the real work.
finding the sweet spot (if there is any: imo this is mostly wishful thinking unless we're talking mic/preamp interaction: there even drastic mismatches can yield pleasing results) across multiple gear may be fun to do in a small private studio but is certainly not a viable option in a commerical studio (nor in broadcasting nor in live sound) - and setting gear to fixed levels is nothing else than making use of the available headroom; max. headroom however imo is not an achievement per se: my mci jh500 has amongst the highest headroom but it isn't much useful if all the gear connected to it is at permanent risk of getting overpowered/clipped...
Old 1st January 2020 | Show parent
  #30
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Quote:
Originally Posted by deedeeyeah View Post

the only minor issue is that it's not a fixed level solution which you were originally looking for - for this, you'd use attenuators and stick them before the clarett's rear panel inputs.

sorry for the confusion!
I did want a fixed level solution but is that really important. What difference does it make?
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