RTA Mic pre-amp for PC used with REQ

[thymej]

I’ve read other threads about needing a pre-amp for the RTA mics out there. I’ve seen the ROLLS MP13 mini-mic pre-amp recommended. ThomasW has good writeups on whats needed for doing RTA stuff for the DEQ/FBD. Why not use the Behringer UB802 mini mixer. It has two XLR mic inputs with phantom power? The ROLLS is $80 and the UB802 is $49 at Part Express. The reported THD clamed by each vendor on paper, the UB802 is better. Cost is also cheaper. Just have to make sure you set all the EQ settings on the UB802 to 0 (or flat) to do RTA readings.

Just want our thought before I go out and purchase a mic pre-amp for my ECM8000 (MP13 vs the UB802). I tried using just a phantom power unit and the ECM8000 just does not have a strong enough signal for the PC to use RoomEQ.

ThymeJ

[ThomasW]

No electret mic has enough output to work without a preamp. Phantom power feeds the capsule, it has nothing to do with the output from the mic

The benefit to the Rolls is that it's very small and compact. And you don't need to worry about getting the tone controls in the detent position, which is something that must be done with the Behringer.

If cost is the factor of course get the UB-802

[Dennis H]

And hope the response of the Behringer is actually flat with the controls in the detents.....

[Paul H]

I couldn't confirm that Dennis - I can however confirm that the response is not flat when one of the controls is accidentally turned up or down. 8O

Paul

[thymej]

I'l let you know since I will pick one up at Guidar Center for $40. Being that I will only use it to take readings from 10Hz to 150Hz, I only care about the 10-80Hz since my crossover is 80, I will see what the 80Hz knob does to a reading between 10-80.

My DEQ is connected like this: Denon-AVR to DEQ to Amp to Sub, so the DEQ will only see the 80Hz and below.
I'll also jave to compare what the DEQ-RTA sees compared to what I see with the PC/RoomEQ/UB802/ECM8000 combo.

[Jack Gilvey]

The UB802 is mentioned and recommended in this thread:

http://www.avsforum.com/avs-vb/showthread.php?t=572477

I went with the M-Audio MobilePre USB also mentioned there which I use with the ECM8000.

[thymej]

Here are some sample screen prints of the effects of the lo tone control knob labeled 80Hz on the UB802. As you can see, when it comes to measurement sweeps of 10-100Hz, the 80Hz control will only lower or raise the whole range.

The file name Lo80HzSetTo0.jpg the 80Hz control knob is set to 0

The file name Lo80HzSetTo+6.jpg the 80Hz control knob is set to +6

[ThomasW]

It would be interesting to pop the top of the 802 and look to see if the connections on tone controls could be jumpered, to take the tone control out of the circuit. They maybe surface mount technology, would make using jumpers problematic.