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Mic Pre - ART MPA Gold question

OK, I know ART isn't the best mic preamp, but I have an MPA Gold and I am a little confused about the gain staging. I am hoping that there is someone out there that may have one that can help.

The MPA Gold has a "tube warmth" meter and a VU meter that measures output. I am not used to working with VU meters and was trying to research what it should optimally read. What reading am I shooting for when sending this out to my Roland VS1680 for recording? From what I have read it looks like I should shoot for zero. It just concerns me that since this is reading RMS that I have all kinds of peaks that I would normally see on a digital meter.

Also, I am not clear on the "tube warmth" meter. Here is what the manual states:

"Tube Warmth Meter
The LED meters monitor the operation of the tube section. The meter reads both the average and peak level. Average levels are shown as a histogram. Peaks are held for one second by a single LED. In “normal” plate voltage mode “0” on this meter indicated less than 5dB of headroom, and a great deal of tube warmth. Monitor the average levels to gauge the tube warmth, as most of the peak levels held are so short they contribute little to the perceived warmth. In “high” plate voltage mode there is more tube circuit headroom. “0” on the meter indicates less than 10dB of headroom."

Does this mean that I can peg this meter and still have 5db (or 10db depending on settings) left of headroom?

Anyone have some experience with this unit?

Thanks in advance for any help.



Link555 Fri, 05/15/2009 - 11:24
An educated guess might be:

-given the max ouput 27dBu(17.3 VRMS or 49Vpp)

0 VU = +4dBu(1.23Vrms or 3.47Vpp)

or –10dBu (0.245Vrms 0r 0.69 Vpp) output,

Its Switch selectable....

So 1.23Vrms in dBfs is roughly -15dBfs

Hope that answers the first question,

Q2: I think the "tube warmth" meter is some way to indicate the distortion level. The louder the input to the final gain stage is... the larger the value on the "tube warmth" meter. There are two meters one for peak values and one for rms.

This seems like a gimic to me, I would use my ears first.


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