Topic: using TASCAM DR-2d with CA-9100

[genesisoh]

I'll be recording a few shows this week and am using the CA-9100 preamp for the first time with my TASCAM DR-2d.  Basically the configuration will be CA-14 cards > CA-9100 > LINE IN > DR-2d.  Both shows will be rock shows with one being about 1/2 way back (center) in an open air arena that seats 20000 and the other show being right in front of the stacks (I'll actually use CA-14 omnis for this one).  So both shows will be loud (i.e., I'm not recording a bluegrass festival :-) 

I understand about the gain settings on the 9100 (11:00 is BB and 5:00 is 20db gain) and about the pre clipping lights.  However I am still confused about what I should set the DR-2d recording level to. Should it be set to 100 (or something lower)?  I'm recording in 24/48, so I can err on the side of lower volume because it can be boosted in post.  I basically want to set the DR-2d and then use the CA-9100 to add/lower gain (if needed) to get respectable recording levels. 

Thanks in advance.

[Gutbucket]

Start at 100 line-in on the DR2d, CA-9100 at minimum gain. 
Adjust from there like this: 
If you need more gain, add it with the CA-9100. 
If you need less, turn the DR2d down. 

Be aware that if you need to go much below mid 90's on the DR2d line-input, you may risk overloading (brickwalling) the input.. but since the alternative is clipping the ADC do it anyway, hope for the best, and note if it worked out alright so you'll better know how far you can push the envelope the next time you record something with similar SPLs.  If you do brickwall it, you'll need to use attenuators.

[Church-Audio]

Start at 100 line-in on the DR2d, CA-9100 at minimum gain. 
Adjust from there like this: 
If you need more gain, add it with the CA-9100. 
If you need less, turn the DR2d down. 

Be aware that if you need to go much below mid 90's on the DR2d line-input, you may risk overloading (brickwalling) the input.. but since the alternative is clipping the ADC do it anyway, hope for the best, and note if it worked out alright so you'll better know how far you can push the envelope the next time you record something with similar SPLs.  If you do brickwall it, you'll need to use attenuators.

Good advice. The control on the DR2 is analog. This can be used as for attenuation when less gain is needed. Always run the 9100 at max when using these recorders.

[genesisoh]

Start at 100 line-in on the DR2d, CA-9100 at minimum gain. 
Adjust from there like this: 
If you need more gain, add it with the CA-9100. 
If you need less, turn the DR2d down. 

Be aware that if you need to go much below mid 90's on the DR2d line-input, you may risk overloading (brickwalling) the input.. but since the alternative is clipping the ADC do it anyway, hope for the best, and note if it worked out alright so you'll better know how far you can push the envelope the next time you record something with similar SPLs.  If you do brickwall it, you'll need to use attenuators.

Good advice. The control on the DR2 is analog. This can be used as for attenuation when less gain is needed. Always run the 9100 at max when using these recorders.

Thanks all for the good advice!  So I should start out with the DR2 at 100 and the 9100 at MAX, then turn down the levels on the DR2 if needed (but always keep the 9100 at MAX - unless of course it is clipping).  And this advice is specific to this recorder.  If I got it wrong, please let me know.

Thanks again.

[Gutbucket]

Ummm.  Some conflicting info there.

Here's how I see it, hopefully Chris can confirm or correct any mis-statments-

The 9100 by itself probably has an optimal signal to noise ratio at it's maximum gain setting, so excluding everyting else, that's were you'd prefer to set it for best performance.  Problem is that doing that might produce an output signal so strong as to overload the line-input stage of the DR2d.  I'm not sure what the minimum gain available on the 9100 is but if it produces output at it's minimum gain setting (meaning it doesn't mute the output when turned all the way down, some preamps do), your safe bet is to start with the 9100 turned all the way down (not up) and the DR2d turned all the way up (100).  If your levels are too low, turn up the gain on the 9100 until the levels are were you want them on the meter.  Otherwise, if your levels are too high and are peaking or close to peaking, leave the 9100 at it's minimum setting and turn down the input on the DR2d.

Which way you'll need to go (up on the 9100 or down on the DR2d) depends on the SPL where you are recording and the sensitivity of the mics you are using. Since the CA-14 mics are designed for recording loud music and are not overly sensitive, I suspect you'll be turning the 9100 up, which puts you closer to the ideal signal level for best performance from the preamp.  But not overloading anything in the recording chain is far more important, so if you are close to a stack and things are really loud, you may need to reduce the gain on the 9100 as much as you can and still turn things down even more on the DR2d.

Hope that makes sense.

[Will_S]

I would have thought the above (Gutbucket's) approach was the way to go as well, but maybe the 9100 adds some nice flavor when pushed harder.

Be aware that if you need to go much below mid 90's on the DR2d line-input, you may risk overloading (brickwalling) the input..

Have you confirmed this with a known good source signal?  I did some testing that has me pretty convinced the MIC-in can go as low as 67 without brickwalling (didn't try 66, 65 will brickwall if fed a signal that is full scale on the meters at that level).  But I found that all of the consumer-line level SOURCES I had available to me started clipping their output if I tried to get a signal hotter than what registered as full scale at line-in in the mid 90's.  It wouldn't surprise me if it could take a hotter signal, though obviously I don't know that for sure.  Seems odd though that the mic in could usefully go down much lower than the line in (of course, it's also odd that mic in can't usefully use 2/3 of the input adjustment level range except if you want a recording peaking well below 0 dBFS - which actually might make some sense for the "mix" mode.).

[Gutbucket]

I've not run actual input level tests to check where it bricks before full scale.  There's been discussion and some testing in the DR2d thread by ToddR (& perhaps by you Will, I don't remember who else).

For my use, I run the mic input at 67 and the line input at 100 most of the time, simply because that's were their sensitivities are about equal, and the line-input level adjustment appears to be some form of attenuation control so I err towards using no attenuation unless necessary. 

I've adjusted the line input down to 95 or so and the mic input to 63 for some louder stuff when I can't actively check levels, just to make sure I'm safe from clipping, but levels did not get within a few dB of full scale so I'm uncertain it would have overloaded with a few more dB or if that was even necessary.  I really only do that because I want to keep gain matched across all four channels and it's a PITA to adjust the gain evenly across all four channels of the two CA-UGLYs I'm using with it.

[genesisoh]

I would have thought the above (Gutbucket's) approach was the way to go as well, but maybe the 9100 adds some nice flavor when pushed harder.

Be aware that if you need to go much below mid 90's on the DR2d line-input, you may risk overloading (brickwalling) the input..

Have you confirmed this with a known good source signal?  I did some testing that has me pretty convinced the MIC-in can go as low as 67 without brickwalling (didn't try 66, 65 will brickwall if fed a signal that is full scale on the meters at that level).  But I found that all of the consumer-line level SOURCES I had available to me started clipping their output if I tried to get a signal hotter than what registered as full scale at line-in in the mid 90's.  It wouldn't surprise me if it could take a hotter signal, though obviously I don't know that for sure.  Seems odd though that the mic in could usefully go down much lower than the line in (of course, it's also odd that mic in can't usefully use 2/3 of the input adjustment level range except if you want a recording peaking well below 0 dBFS - which actually might make some sense for the "mix" mode.).

I can now confirm this.  Last night I was recording a loud show close to the stacks.  I decided to set the DR to 90 and start off with the 9100 at 11:00 (no gain).  Once the show began I noticed that there was no clipping and in fact ample room for DB increase.  Now what I should have done was to start raising the DR levels, but instead what I DID do was to crank the 9100 to max (20DB gain).  It wasn't clipping and the levels on the DR looked fine.  What I didn't notice, and that I now know to look for, are levels that don't bounce around much.  The resulting recording had moderate brickwalling in one channel.  I should mention that I recorded in 24/48 if that makes any difference.  It sounds ok, but I am sure there is some overloading on that one channel that is not intense enough to be obvious. 

So my lesson here for recording near stacks or in a very loud environment is to set the DR at 100 and the 9100 at 0, then lower the DR if clipping.