VTB-1 input gain question

[jhebert]

I'm using an EV RE20 (picked up from a friend who did a voice over project) as a general vocal mic to create some demos for a friend's acapella group. It's the nicest mic I have, so I'm using it.

Signal chain is RE20 to VTB-1 to CardDeluxe (in a PC running Sound Forge).

However, I need to run the input gain on the VTB-1 at about 54-60 dB, with the output level at 12 dB, to get a strong signal into the computer. The card sets XP's audio mixer levels at max, which it terms "unity," so there's no further adjustment there; and Sound Forge has no gain in its record panel, so the VTB-1 is all I've got.

I have two problems, I think.

One - where should levels be peaking when I record? I'm getting peaks around -6 dB only with the knobs nearly cranked to their maximum on the pre. Is this normal? I would expect a lot of hiss at these levels, but it sounds pretty good so I may be concerned about nothing that important after all. Is there a preferred avg or peak signal level I should be attaining on the average?

Two - should the recorded waveform be symmetrical? I don't think it's a DC offset issue (running the DC offset function changes nothing), but above the centerline a peak might hit -6 dB, where below the same peak only goes to -12 dB. When I look at a ripped CD track, they're pretty symmetrical, but my recordings are not. Any ideas what to look into on this?

Thanks for your help, questions, or comments!

James

[Scott Collins]

RE: Levels

Alan offered in another thread that the VTB1 sounds a bit better when you run the input gain just a bit hot (with occasional peaks over 0dB). I've tried this and I think this is a non-trivial tip: it does make a difference to my ears when recording vocals (and probably anything). Don't know about the mic you are using, but sounds a little odd that you would have to push the gains on the VTB1 so hard.

I think the level to the sound card should be significantly lower to avoid any kind of clipping/distortion. Sounds like you are on track there: peaks should be -6dB maximum, and it's probably better if they are even a little lower. That's just what I've gleaned reading on the subject, though.

Don't know the answers to your other questions, but someone else will probably chime in.

[Alan Hyatt]

I'm using an EV RE20 (picked up from a friend who did a voice over project) as a general vocal mic to create some demos for a friend's acapella group. It's the nicest mic I have, so I'm using it.

Signal chain is RE20 to VTB-1 to CardDeluxe (in a PC running Sound Forge).

However, I need to run the input gain on the VTB-1 at about 54-60 dB, with the output level at 12 dB, to get a strong signal into the computer. The card sets XP's audio mixer levels at max, which it terms "unity," so there's no further adjustment there; and Sound Forge has no gain in its record panel, so the VTB-1 is all I've got.

I have two problems, I think.

One - where should levels be peaking when I record? I'm getting peaks around -6 dB only with the knobs nearly cranked to their maximum on the pre. Is this normal? I would expect a lot of hiss at these levels, but it sounds pretty good so I may be concerned about nothing that important after all. Is there a preferred avg or peak signal level I should be attaining on the average?

Two - should the recorded waveform be symmetrical? I don't think it's a DC offset issue (running the DC offset function changes nothing), but above the centerline a peak might hit -6 dB, where below the same peak only goes to -12 dB. When I look at a ripped CD track, they're pretty symmetrical, but my recordings are not. Any ideas what to look into on this?

Thanks for your help, questions, or comments!

James

What setting is the impedance switch set to on the rear? Also, what output connector are you using on the rear of the VTB1?

[jhebert]

Thank you, Scott and Alan. I appreciate your comments, and your time.

As an aside, I was once told by an engineer that the RE20 needed to be run by a preamp with more oomph. At the time, I was trying it out with a Mackie 1202 VLZ, with their newer/better preamps, and I just never got a lot of signal. That's one of the reasons I turned to the VTB-1 (which I think is a terrific preamp, by the way), it's higher gain.

Still, I have a tendency to "hold back" from setting the input gain so high, fearing electronic noise in the sound. Again, I must admit, I heard little to none, which was both surprising and cool. (Did I mention I think this is a terrific preamp?)

To answer your questions, Alan: since the RE20 is spec'd at 150 ohms impedance (http://www.electrovoice.com/documents/RE20_EDS.pdf), I have the switch out, which is 200 ohms. The mic comes in on balanced XLR. The 1/4" Line Out from the VTB-1 goes directly to the CardDeluxe in.

UPDATE 1: I've tried both the 200 and 50 ohm switch positions, and get a much stronger signal at 200.

UPDATE 2:
I have discovered something that has bearing, I think. I was sending the output of the VTB1 to the CardDeluxe on channel 1. In Sound Forge, when I choose Mono in the recording panel, both L and R rec meters both show signal presence. When I choose Stereo, only L shows signal present.

Here's what's odd: in stereo mode recording, the same input signal peaks about 3 dB higher than it does in mono mode.

Not sure why this is so... in fact it seems odd/wrong to me. I would not expect a difference in signal level for either recording mode. I cannot tell yet whether this is a software behavior (which I suspect), or something in the hardware. I think I'll try a few other and see if they behave in the same manner.

James