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Gear / Technical Help => Ask The Tapers => Topic started by: tbger on May 11, 2013, 05:33:37 AM
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(originally "CAFS straight into M10 (mic in) -- overloaded recording. Help me learn my lesson")
The show was quite boomy in bass that I could feel my trousers moving. I thought the extreme highs and the low bass were too loud where I was standing (right where the sound desk was), my guess is that since it was at a park and in front of more than 15,000 people, the sound had to be loud enough so that those standing away from the stage could hear and feel everything.
I was running CAFS straight into PCM-M10's mic in, with recording level set at 7.
I've taped a lot of shows using CA14 > CA-9100 > PCM-M10's LINE-IN, with very nice results. Thought I'd give the CAFS a try, without the preamp, but oh the remorse ...
The single was hot at the recording, and every time there's a bass punch, it overloads. You know it when you can't hear clapping between songs clear enough, and you kind of hear only the loudest claps which 'depress' the rest of sounds ? ... Sorry my description is bad but I hope you get the idea. :)
What could have been wrong with my setup ? Is it the CAFS not being able to handle such strong bass ? Or do they need a battery box to do that ? Is it the recording level, or the fact I didn't use an external preamp ?
I haven't taped for more than a year and honestly forgot to watch my levels. In post (sound editing programs) it looks like obvious overloading, which might imply I should have lowered the recording level. Would that really help ? In my experience when a mic can't handle bass it will overload no matter what level you record it at.
Thanks for any help
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SSIA...
I know you occasionally see opinions to the opposite round here but I don't touch the 'mic-in' on any recorder unless I'm absolutely desperate for some extra gain that can't be provided from elsewhere.
Battery box/preamp into line-in and you can't go far wrong.
Edit to add: also, 7 sounds a bit on the high side to me - maybe that played a role too...
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I just did a LINE IN with the M10 recorder dial on 8 with no problems after Todd R. made a comment
about no real ill effects from going past "Unity Gain" 3 to 5ish on the M10.
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By the way, I don't have the M10 around, but as far as I remember the recording level knob isn't functional when going LINE IN.
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SSIA...
I know you occasionally see opinions to the opposite round here but I don't touch the 'mic-in' on any recorder unless I'm absolutely desperate for some extra gain that can't be provided from elsewhere.
Battery box/preamp into line-in and you can't go far wrong.
Edit to add: also, 7 sounds a bit on the high side to me - maybe that played a role too...
Thanks.
I'll try to see what I should have used in this case, a preamp or a battery box. I guess I don't know enough to figure this out myself.
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By the way, I don't have the M10 around, but as far as I remember the recording level knob isn't functional when going LINE IN.
Not sure where you got that... The recording level knob is functional when using line in.
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I think I read it somewhere on the "Sony PCM-M10 (Part x)" a few years back. Anyway that's great to know, thanks :)
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I think the problem most likely was in the absence of bbox or preamp. Its not easy to overload m10's mic input. It may happen on levels below 2, but not on 7.
Edit: well, if you did not watch your levels, it may be just clipping.
The single was hot at the recording, and every time there's a bass punch, it overloads. You know it when you can't hear clapping between songs clear enough, and you kind of hear only the loudest claps which 'depress' the rest of sounds ? ... Sorry my description is bad but I hope you get the idea. :)
Sounds like hard limiting = clipping to me.
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Hey Tim,
Thanks for your input.
Its not easy to overload m10's mic input. It may happen on levels below 2, but not on 7.
First of all I'd thought clipping and overloading describe the same thing. Isn't it so ?
My intuition about this was: the higher the recording level, the more chances you overload the recorder. I guess I'm wrong ?
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I think I read it somewhere on the "Sony PCM-M10 (Part x)" a few years back. Anyway that's great to know, thanks :)
the recording level knob is functional well when going LINE IN but changing the MIC SENS knob doesn't change anything when going LINE IN - I suppose that's what you read and was in your mind. I've had lots of distortion when going mic in at a very loud concert at level 4 (!!!) and using a battery box (PIP switched off in that case). That was back then when I learned my lessons - never went mic in again ;D
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^^^ thanks a lot for your input, taper666. That's surprising to hear ... lesson learnt here as well now ! :)
Also thank you for the clarification on the level knob and sensitivity switch. I was confusing the two probably.
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@simplemind:
Taper666 is right. The general rule is to use line-in instead of mic-in when you can and *always* use bbox or preamp to provide enough (9v) power to the mics. Use 24 bit and dont worry that the levels will be too low. You can boost them in post. When I'm taping my levels are usually bouncing between -20 and -12db.
Clipping occurs when the wave goes above 0db and gets cutted. The overload (=brickwalling) may happen even if the levels are below 0db. It depends on how loud the signal actually is. The louder music is - the lower level setting you use to keep the levels below 0db, and at some point the overload begins. Line in can take hotter signal than mic-in - thats why you should prefer it for loud shows. It is useful to make some tests with your home stereo or at a cheap local show and see how it goes.
Anyway my experience tells me that micin overload cant happen at level 7. I've recently taped several loud shows at setting 5 mic in with the levels peaking at -12db.
And always set the mic sensitivity switch to low, unless you tape something extremely quiet.
That's as much as I can tell. :)
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Hello Tim,
Let me know if I got you clearly: if overload didn't happen for you at rec. level 5, it will necessarily not happen at 7 ? I mean, does chances for overloaded-signal lower as the rec. level goes higher ?
Thank you again :)
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Quick summary: For a loud show, send the mics through a battery box or preamp into line-in. A battery box is all you need for loud amplified music.
Here's why:
A Mic-in jack does two things. It provides power (Plug-in power on the PCM-M10, a few volts) to the mic and it sends the signal through a built-in preamp.
The Line-in Jack, meanwhile, is for a signal from something amplified or powered, so it provides neither power or preamp.
Going through Mic-in, overload can happen at two different spots in the recording chain:
1) It can happen at the mics themselves--mics can only handle a certain sound pressure level (volume), particularly in the bass.
2) It can happen in the preamp, and again megabass is the quickest to overload it. If you had the mics at Hi Sensitivity, the preamp is boosted higher and overloads faster.
To help prevent (1) you provide more power to the mics, either through a battery box (which is generally all you need at loud shows) or a preamp (which, turned to zero gain, is essentially a battery box); more power helps them handle higher volumes.
(2) To skip the built-in preamp in the unit, you go through line-in with a better preamp or a powered signal (via battery box) from the mics. For loud shows, a battery box into Line-in works well because it's loud enough--you don't need amplification from the preamp.
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^^^ That's very helpful, thanks a lot.
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Let me know if I got you clearly: if overload didn't happen for you at rec. level 5, it will necessarily not happen at 7 ? I mean, does chances for overloaded-signal lower as the rec. level goes higher ?
Generally speaking, yes. Because you most likely will use higher level for *quieter* music, so there'll be less chances for overload.
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When the claps "depress" the rest of the sound it means you are running too high, and using the auto-limiter function. You are better off not using the auto limiter (arguably) because if it comes into play it sounds terrible anyway, so just learn to run at a reasonable level. The M10 LEDs are great for this- you want to see the green lights come on a least every once in awhile, but you don't want to see the red ones more than flash every once in awhile. Green is -12dB (a reasonable recording level at 24 bits) and Red is approaching the highest value that it can record. If you have loud claps, then you can remove these in post production using limiter compression which does a similar thing as the auto limiter, but you have control over exactly what it does and an undo button in case that isn't what you expected.
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Hi Eman - that's a great idea. I remember turning the LEDs off when I got the device. Since I'm stealthing, and can't take the recorder out with all the cables connected to it (I also use the remote), I can't really know what's going as far as levels go. This could help me a lot.
It was the remote's cable and the other 1 or sometimes two cables running from the device, that made me not take out the device for checking for levels. It wasn't the case when I last taped a concert, but that was about two years ago, and since then I taped hundreds of lectures with the remote, so the whole issue of levels wasn't on my mind at all and I forgot that with time of using the device daily. BTW, an awesome device (M10) - and mics (CAFS) - made hundreds of lecture recordings with not a single fail !
Good idea again, thank you ! ;)
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Bring it to some events that don't require >:D and learn where your rig needs to be set up for different volume ranges. I just got caught being too conservative last week with levels so low that I got hiss when I normalized it. It's been a long time since I had a hissy recording!
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Hello everyone,
Here to report I tried the CAFS again, hooked directly to my PCM-M10 (didn't have the CA-9100 handy once again) for a Pet Shop Boys show in a closed hall. This time I set the recording level to just 3 on my M10 (40% of previous time). The recording turned out fantastic, balanced and without any distortion. This time I was sitting right in front of the stack.
I do keep in mind the bass wasn't as strong as the previous show (a Depeche Mode show that time), and therefore am still doubtful as to whether these mics can hold strong bass SPLs without overloading, without a battery box / a preamp. Better not take the risk of course, but the this last outcome is very tempting to give it a try.
Cheers
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Hello everyone,
Here to report I tried the CAFS again, hooked directly to my PCM-M10 (didn't have the CA-9100 handy once again) for a Pet Shop Boys show in a closed hall. This time I set the recording level to just 3 on my M10 (40% of previous time). The recording turned out fantastic, balanced and without any distortion. This time I was sitting right in front of the stack.
I do keep in mind the bass wasn't as strong as the previous show (a Depeche Mode show that time), and therefore am still doubtful as to whether these mics can hold strong bass SPLs without overloading, without a battery box / a preamp. Better not take the risk of course, but the this last outcome is very tempting to give it a try.
Cheers
Here is the deal with my gear.
If you have a 9100 use it. Reduce the level to 80% leave it there, run the preamp into line input shoot for -10 db on your VU and you should be good to go. The mics are much less likely to overload with my preamp because of the higher bias voltage. You can always get away with going straight in if the sound pressure level is not that loud.. But the main problem is you don't know what "not that loud" means and have no way to measure it. Not that loud for my mics would be around 98 db anything much over that with low bias voltage you will get overload with a battery box or preamp my mics have less than half a percent of distortion at 114 db at 1k. My mics will not overload my preamps unless they are put inside a kick drum.. You would not be able to stand SPL that loud.
So use the preamp you have whenever possible use a good quality battery with it. Make sure you USE line input always.. Unless you are recording acoustic stuff then you can use the mic input and my preamp carefully. I dont know what unity gain is on the D10 BUT thats a good starting point for you to go with.
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Thank you for these helpful hints Chris.
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I've used my 9100 at MAX and my m10s gain knob on 8-10 and the show turned out fantastic. I used LINE IN tho ;) Like everyone has said, ONLY use the MIC IN when recording acoustic or music with much lower SPLs. I would NEVER risk a recording without a battery box or preamp. It's been noted a million times that recordings get distorted without them, so if you have either one, why not use them?
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Thank you for these helpful hints Chris.
No problem you or anyone else can always email me about questions regarding my gear or anything else audio related.