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Gear / Technical Help => Battery Boxes, Preamps, Mixers, ADCs, and Processors => Topic started by: achabloop5080 on February 12, 2012, 07:01:11 PM

Title: Leaving SD UsbPre 2 phantom power always on?
Post by: achabloop5080 on February 12, 2012, 07:01:11 PM
Hi guys,
I've got a brand new SD USBPre 2 and so far I like it very much.
Great quality and great DAC.
But there is a little problem: switching phantom power on and off on location is not very friendly....
I can switch on and off phantom powering through very little dip switch on the rear with a slender tool, but what if I leave phantom power always on?
Obviously I'd connect/disconnect xlrs only with the unit turned off, but then when I turn on the USBPre 2 phantom power is already engaged....
Could it damage my wonderful Schoeps MK21g pair?
Any advice?
Please share your experiences and suggestions..
Thank you
Title: Re: Leaving SD UsbPre 2 phantom power always on?
Post by: acidjack on February 12, 2012, 07:20:52 PM
Plug in the mics first. Everything will be fine.
Title: Re: Leaving SD UsbPre 2 phantom power always on?
Post by: page on February 12, 2012, 07:24:21 PM
Plug in the mics first. Everything will be fine.

ditto.

I've left P48 on with every recorder I've had, including my 722. It has to energize sometime. Turning it on when the machine comes on or when you flip switches is essentially the same effect.

Now, I don't leave mine on with the usbpre2, but that's because I use mine as a dac/soundcard the vast majority of the time. When I pack up to use it at a show, I'll flip it on at home and then package it up so it automatically comes on when I'm in the field.
Title: Re: Leaving SD UsbPre 2 phantom power always on?
Post by: achabloop5080 on February 13, 2012, 11:45:36 AM
Thank you guys,
now I'm more relaxed....
:-)
Title: Re: Leaving SD UsbPre 2 phantom power always on?
Post by: dallman on February 13, 2012, 03:08:58 PM
The design of the dip switches is such that the settings would be retained. Easily changed, but not "on the fly" changing. I keep p48 on always. Hey there is not even an "on-off" power switch, so attach power and you are off and running. I always attach power last, but again, I always have p48 on.

And FWIW, I have used a Tascam HDP2 for many years and have never turned the p48 switches off. I never power up until everything is attached, but it has never been an issue and if I did it any other way, I am sure I'd forget to throw those switches from time to time.  ::)
Title: Re: Leaving SD UsbPre 2 phantom power always on?
Post by: DSatz on December 23, 2012, 02:34:11 PM
Old thread, I know, but ... I was the translator and co-writer of the manual for the OP's Schoeps mikes, and AFAIK the main reason manufacturers advise people to connect microphones before turning on the phantom powering is to help you avoid consequential damages--the Big Bang that can course through your preamps, and possibly power amps and headphones and/or loudspeakers if connected, thus possibly damaging transistors, speaker cones and/or your and other people's hearing.

But while I'm not saying that this is something you should always do, it should really be no hazard to a properly designed condenser microphone if you connect it while (correctly implemented) phantom powering is turned on. Heck, at trade shows people from Schoeps change capsules on their mikes while leaving the power on, although that isn't recommended everyday behavior, either (plus they have a stockroom full of replacements in case something does blow up--but I've never heard of it doing so).

This should all be rigidly distinguished from parallel powering (a/k/a "T" powering), which can definitely damage dynamic microphones (particularly ribbons), but fortunately is rarely used any more.

--best regards