Topic: attenuant at the mics or recorder?

[willndmb]

here is my situation...
i have (mics) > Littlebox > Sony PCM-M10
the few times i have been able to run it i am running hot or very close to it
my question is basically which is better - to attenuate at the mics via -10db pad OR use the dial on  the side of the M10 to attenuate there?
if it makes a difference i am going xlr in on the lb and the gain is all the way down
thanks for the input

[stevetoney]

I don't know which is better technically, but I know in your situation I'd 100% be flipping the mic switch to give me max recording headroom.  I'd much rather have access to the headroom than be worrying about riding the red line and going back to having watch my recorder like a hawk during a show, but that's just me. 

[Husker Du]

There was a pretty good discussion here: http://taperssection.com/index.php?topic=132272.0

[guysonic]

Mic input sensitivity switch is preamp GAIN control, and should always be in LOW for quality and headroom.   I your knob is near the bottom, then you have this set in HIGH, and this is wrong.  Here are my tips for getting the best from this model deck:

TIPS: (For highest quality recording purposes)

Use M10 ONLY set in 24 bit recording mode.  Sample rate is your choice, but suggest using 44.1K sample rate if wanting best CD compatible editing options.

Use M10 ONLY with MIC INPUT sensitivity switch set in "LOW" taping over this switch to not be moved.  "HIGH" setting is way too much 20 dB boosted first stage gain giving inferior audio quality.  Even with very low VU levels, LOW setting gives cleaner more defined 24bit depth audio best boosted in post edit, NOT by using deck in HIGH setting.

Use M10 in full manual (not AUTO, Limiter) record level control mode setting also taping over this switch. 

Wise tact is to always engage HOLD feature so touching buttons do not accidentally stop recording until you're ready to stop the session. 

Do all editing in 24 bit mode, adjusting loudness and other changes desired.  Then as last software edit step convert copy of file to 16 bit if later doing CD storing this copy of file for disc burning purposes.

See taperssection.com M10 comments/tech data GuySonic posted at: http://taperssection.com/index.php?topic=130924.0;all 

[Walstib62]

Isn't the output of Littlebox a line level signal? If so, then you would want to connect the LB output to the LINE IN of the M10. Then set the M10 input to around 35-50% of max gain, and use LB as your gain fine adjust. If you attenuate using the mic pad, you will be adding noise to the mic output signal.

[stevetoney]

Isn't the output of Littlebox a line level signal? If so, then you would want to connect the LB output to the LINE IN of the M10. Then set the M10 input to around 35-50% of max gain, and use LB as your gain fine adjust. If you attenuate using the mic pad, you will be adding noise to the mic output signal.

...except he said he's got his LB dialed all the way down and he's still riding the red line, so he can't get to 35-50% of max gain (unless you're using mic-in, which I'm confident you're not).

[bhadella]

The littlebox's minimum gain is 6 dB (or 18 dB with the optional +12dB input transformer) paired with typical condensor mics should have plenty of headroom.   I think the issue lies with the settings on the M10. 

[page]

The littlebox's minimum gain is 6 dB (or 18 dB with the optional +12dB input transformer) paired with typical condensor mics should have plenty of headroom.   I think the issue lies with the settings on the M10.

I concur, line in on the M10 is of 7XX proportions (like +26dbu), for there to be no additional gain at the littlebox stage and close to clipping would require an attrociously loud noise of 140db proportions or incorrect settings on the M10 (such as mic-in). Since he can still hear, I'm betting it's the M10.

[willndmb]

i AM running Line In
however at some point my Mic Sens did slide to HI (lesson learned there - gaff it)
but if i am going line in does that switch even affect anything?

EDIT just did a white noise test and the high low had no effect when going line in

[Walstib62]

Something still isn't adding up here. If you are in fact using the line input, you should have no problem. The fact that the M10 input is overly sensitive is the issue. If this continues to be the case, you may need an inline attenuator at the M10 input. You need to be operating your gain settings closer to the middle rather than everthing set at minimum. Good luck.

[page]

i AM running Line In
however at some point my Mic Sens did slide to HI (lesson learned there - gaff it)
but if i am going line in does that switch even affect anything?

EDIT just did a white noise test and the high low had no effect when going line in

Ok, so next set of questions;

What's the configuration of your LB? Did you get input/output trannys? Do you have a high/low gain switch or just the knob? Last, I'm assuming it's with your AKGs.

Another test I'd do (to at least get a better handle on what's going on) is: Take your stereo amp/dac and send a tone through it (say, -10db, maybe -15db). See what you get when you hook up the LB to your fr2le (use a 3.5mm>1/4" jack, only need 1 track). and measure the resulting db reference (and add any gain needed to get near 0). Now, remove the adaptor and try the M10 (after verifying that it's set to line in, and the gain is around 4 on it). You should get significantly less since the fr2le clips around +4db while the M10 when near it's unity gain won't clip until the +20 range. If the signals are the same, then there is something wrong with the M10, if you can't get low enough on the LB to keep the fr2le from clipping, it's the gain structure as I would think the baseline +6db while dailed down would still keep a line signal under the +4db limit.

Something still isn't adding up here. If you are in fact using the line input, you should have no problem. The fact that the M10 input is overly sensitive is the issue. If this continues to be the case, you may need an inline attenuator at the M10 input. You need to be operating your gain settings closer to the middle rather than everthing set at minimum. Good luck.

I can't believe that he's sending that much signal to the M10, that's crazy. 

[stevetoney]

I think from reading your first post that you know this, but the 480b has switchable attenuation (three positions; 0db, +6db and -10db).  The online schematic shows that the switch is on the inside of the mic body.  Perhaps your issue is that your particular 480s are set to highest sensitivity setting, but for rock music you'd obviously want them set for lowest sensitivity.

Does the problem persist when you record with your Busman mics?

(FWIW, I think those that are discussing attenuation earlier in this thread have been referring to the sensitivity switch on the side of the M10, not the switch on the inside of the mic bodies.  My first response to your question suggested that I'd for sure have the mic switch set at lowest sensitivity...but others have pointed out and you've verified that the switch on the M10 does not have any bearing on the Line In function.)

[willndmb]

page
i an not following you
but would this work...
take a -10db white noise file
play it into the LB > fr2le and i SHOULD see the fr2le meter say -4db (because the lb has 6db gain at the lowest setting and don't add any gain via the fr2le)
then replace the fr2le with the m10 and see what i get for a reading there (with the gain dial on the m10 at 4)


then again how could i hook the lb up to a line signal, i would need to turn the power on somehow

[willndmb]

not sure if this helps at all but i ran the white noise from my stereo to m10 (set at 4) and got it to match db wise
switched the m10 for the fr2le (phantom off of course) and had to set the gain at 12:30 to match the level db wise
changing the trim knobs had no effect

EDIT
now i just played the file via speakers and set my mics up in front
1 akg and 1 bm (they are pretty much matched so that was helpful) > LB (48v) > recorders
i got the same results - for the fr2le to match the m10 db wise on the meter i had to have the gain around 12:30

i am wondering if maybe i had a couple of loud shows and everything is fine??

[page]

page
i an not following you
but would this work...
take a -10db white noise file
play it into the LB > fr2le and i SHOULD see the fr2le meter say -4db (because the lb has 6db gain at the lowest setting and don't add any gain via the fr2le)
then replace the fr2le with the m10 and see what i get for a reading there (with the gain dial on the m10 at 4)


then again how could i hook the lb up to a line signal, i would need to turn the power on somehow

1) Yes, that's basically what I'm after.
2) Is the LB set to "All P48 All The Time" or can you turn the power off? (similar question; how would you run a ribbon with it).

not sure if this helps at all but i ran the white noise from my stereo to m10 (set at 4) and got it to match db wise
switched the m10 for the fr2le (phantom off of course) and had to set the gain at 12:30 to match the level db wise
changing the trim knobs had no effect

Trim knobs won't work when you are using TRS jacks. 

I would have expected that to be flipped. Less gain on the fostex and more needed on the M10. I sounds like it's pretending it's a mic signal.

[willndmb]

you might have missed my mic test above

but my lb has off/48v/20v
then a aux plug for plug in power

[willndmb]

one more test
white noise (line out) > m10 (line in AND out) > fr2le (phantom off)
the m10 showed the white noise exactly
the fr2le had to have the gain turned up to approx 2:00 to match db wise on the meter - thats an increase from 12:30 when receiving the white noise directly from the stereo vs the m10

[Walstib62]

So are you saying that the M10's inputs seem to be more sensitive than that of the FR?
I know there are other M10 owners out there. (not me). Hopefully they can help shed some light on this. I know it's frustrating dealing with issues like this. Again, good luck. It seems like you're on the right track.

[willndmb]

So are you saying that the M10's inputs seem to be more sensitive than that of the FR?
I know there are other M10 owners out there. (not me). Hopefully they can help shed some light on this. I know it's frustrating dealing with issues like this. Again, good luck. It seems like you're on the right track.

yes in my tests the m10 was much more sensitive
the good thing is that i am now onto what needs to be done as far as not clipping so it shouldn't be to much of a problem unless i am really close to the sound source (which sometimes i am )
also on a plus side i did learn that unity seems to be closer to 4 vs 6 which means if was adding approx 4db of gain at the recorder
so all in all i was set up at the sbd running akgs > LB (set as low as it would go, 6db of gain) > m10 (adding 4db of gain)
and was peaking around -2.5
all a learning experience that didn't cost me a bad recording

[willndmb]

good news here
so it looks like the Blues Traveler show was just LOUUUUUUD
ran the same set up for soulive in a club and had to put the gain around 11 to 11:30 to the get same results i was getting at the BT show
not that i want to run that hot but just testing it out
so thanks for those who helped me look into the issue and answer my question of where to attenuate if needed

[fmaderjr]

also on a plus side i did learn that unity seems to be closer to 4 vs 6 which means if was adding approx 4db of gain at the recorder

Unity gain is around 6. Guysonic reported that after performing his famous test.

[willndmb]

also on a plus side i did learn that unity seems to be closer to 4 vs 6 which means if was adding approx 4db of gain at the recorder

Unity gain is around 6. Guysonic reported that after performing his famous test.

yes and in my first "test" i got 6 too
but after doing a series of test after that i got 4 many times so i assume i did the first wrong and guy poss did too

[page]

also on a plus side i did learn that unity seems to be closer to 4 vs 6 which means if was adding approx 4db of gain at the recorder

Unity gain is around 6. Guysonic reported that after performing his famous test.

yes and in my first "test" i got 6 too
but after doing a series of test after that i got 4 many times so i assume i did the first wrong and guy poss did too

john had some questions about that as well when he ran it behind the sax. I'm not saying someone has done something wrong, but a lot of test cases don't seem to match up...

[aaronji]

^^^ I am pretty sure unity is less than 6 (famous tests notwithstanding!).  I read somewhere that 0 dBFS on the M10 is 1 Vrms (~2.2 dBu).  Couple that number with Will's SVU-1 experiment (-3 dB re: -10 dBu on the SVU-1 and -3 dB at 6.5 on the M10), and you'd be adding about 12 dB gain at 6.5...Assuming all the numbers are more or less accurate, of course...

[willndmb]

^^^ I am pretty sure unity is less than 6 (famous tests notwithstanding!).  I read somewhere that 0 dBFS on the M10 is 1 Vrms (~2.2 dBu).  Couple that number with Will's SVU-1 experiment (-3 dB re: -10 dBu on the SVU-1 and -3 dB at 6.5 on the M10), and you'd be adding about 12 dB gain at 6.5...Assuming all the numbers are more or less accurate, of course...

as a follow up aaron (after learning about the svu info) i then made a cd with 3 white noise files
first -10, then -6, then 0
i played it back on my bose via line out (dual rca > 1/8) > M10
on 4 the m10 read the files all exactly as they were -10, -6, 0

bottom line for me is that i had the best results as far as gain is concerned on 4 and it sounds fine to me so i am going to stick with it for now

[aaronji]

^^^ So far, I have heard a 2, a couple of 3s, a 4 and a 6...This is more complicated than a 1040! 

[fmaderjr]

I have to admit willndbm appears to be correct that unity gain is about 4. His results spurred me to record white noise at just below 0dB onto a CD . When I played it back and went line out from the CD player to line in on the M10, it took a setting of around 4 for for the M10 levels to reach 0 dB. My mistake-I thought guysonic's tests were so scientific they couldn't be wrong, but nobody is perfect.

Settings of 2 & 3 are definitely attenuating the signal.

And as illconditioned reported months ago, settings above 6-7 add almost no gain (I tested that with a white noise track peaking at -30 dB). It appears that you can add approximately 14 dB of gain when going line in to the M10, but most all of it is added by the time the record level wheel hits 7/10.

[aaronji]

To be honest, I don't think this definitively answers the question (although maybe I am missing something).  You still need to know two numbers, I think: the voltage that the test signal generates at the CD player's line-out and the voltage corresponding to 0 dBFS on the line-in of the M10.  Then you could figure out the level on the M10 that corresponds to the same voltage coming out of the CD player...

I read somewhere that 0 dBFS corresponds to 1 Vrms, but I can't for the life of me remember where I read it (and can't find it again either), so take that with many grains of salt.  And there is no real standard for CD player line-outs, so that can vary from player to player.

[willndmb]

To be honest, I don't think this definitively answers the question (although maybe I am missing something).  You still need to know two numbers, I think: the voltage that the test signal generates at the CD player's line-out and the voltage corresponding to 0 dBFS on the line-in of the M10.  Then you could figure out the level on the M10 that corresponds to the same voltage coming out of the CD player...

I read somewhere that 0 dBFS corresponds to 1 Vrms, but I can't for the life of me remember where I read it (and can't find it again either), so take that with many grains of salt.  And there is no real standard for CD player line-outs, so that can vary from player to player.

i'll try it on a couple of other players and see what i get
thats the best i can do because i have no way to test the voltage

[fmaderjr]

To be honest, I don't think this definitively answers the question (although maybe I am missing something).  You still need to know two numbers, I think: the voltage that the test signal generates at the CD player's line-out and the voltage corresponding to 0 dBFS on the line-in of the M10.  Then you could figure out the level on the M10 that corresponds to the same voltage coming out of the CD player...

I read somewhere that 0 dBFS corresponds to 1 Vrms, but I can't for the life of me remember where I read it (and can't find it again either), so take that with many grains of salt.  And there is no real standard for CD player line-outs, so that can vary from player to player.

That's way beyond my comprehension-I don't know the technical stuff. Maybe guysonic was right as I should have suspected. However even if unity gain in really 4 and you set the M10 to 6 it shouldn't really audibly effect the recording in a negative way since the M10's pre is very quiet.

[aaronji]

That's way beyond my comprehension-I don't know the technical stuff.

I am not too strong with the technical stuff myself; that's why I try to be careful to put lots of qualifiers in those posts!  In the previous one, as an example, I think you might actually need to measure the voltage from the CD player at the line input on the M10 to account for the input's impedance?  Not really sure...But I am sure about needing to know references for dB comparisons.  dBs are always ratios, so to compare them directly the references need to be known...

Maybe guysonic was right as I should have suspected. However even if unity gain in really 4 and you set the M10 to 6 it shouldn't really audibly effect the recording in a negative way since the M10's pre is very quiet.

Part of one of your earlier posts gives me further reason to suspect 6 as the estimate of unity.  You said:  "And as illconditioned reported months ago, settings above 6-7 add almost no gain (I tested that with a white noise track peaking at -30 dB). It appears that you can add approximately 14 dB of gain when going line in to the M10, but most all of it is added by the time the record level wheel hits 7/10."  Here, the reference level still isn't really known, but since you are comparing everything to dBFS on the M10 it doesn't matter (the unknown quantity ends up being in both the numerator and denominator of the ratio so it cancels).  But your finding, and that of illconditioned, makes 6 seem even more unlikely; I have a hard time imagining that the entire amount of gain you can add is the interval from 6 to 7...

[fmaderjr]

Part of one of your earlier posts gives me further reason to suspect 6 as the estimate of unity.  You said:  "And as illconditioned reported months ago, settings above 6-7 add almost no gain (I tested that with a white noise track peaking at -30 dB). It appears that you can add approximately 14 dB of gain when going line in to the M10, but most all of it is added by the time the record level wheel hits 7/10."  Here, the reference level still isn't really known, but since you are comparing everything to dBFS on the M10 it doesn't matter (the unknown quantity ends up being in both the numerator and denominator of the ratio so it cancels).  But your finding, and that of illconditioned, makes 6 seem even more unlikely; I have a hard time imagining that the entire amount of gain you can add is the interval from 6 to 7...

That certainly makes sense...