Question

My application is using an SM57 for acoustic guitar or vocal input. I have a BlueTube v2 and just acquired a ********* UMC404HD. The preamp on the UMC404HD is OK, but I think I'd be happier with the BlueTube as pre.  If I use XLR out to XLR in, what recommendations are there for gain setttings (both BlueTube and UMC404HD)? What about for the Pad that the UMC404HD has? Also, I assume no need for Phantom power on the downstream UMC404HD.

Thanks for reading/responding.

Answer 1

Knowns: 

• BlueTube with 80dB gain (output level not given); 
• SM57 open circuit voltage: -56dBV/Pa (1.6mV)
• Corresponds to 16V output at BlueTube (max); 80dB gain is 10,000 Voltage Ratio Gain
• UMC404HD line  max input level is +20dBu; 20dBu correspond to 7.746Vrms or 21.91Vpp

So, it seems that the BlueTube if full up would not overdrive the UMC404HD (don't know how it would sound).

Any further opinions on whether the BlueTube would nuke the UMC404HD input? The UMC404HD doesn't provide a Line-in Z (assumed to be 10kohm).