DI XLR to Board XLR wrong??

[FuzzBoxVoodoo]

I just got off of the phone with Allen&Heath in regaurd to turning off the phantom power on my specific channel that goes to my bass Amp or preamp.
The Board (Mix Wizard 16:2) doesn't have specific channel selection for the phantom power and I don't want to damage some of my older Bass gear with the +48volts thru the XLR.
Allen & Heath told me that you are not supposed to hook into the xlr jack on the back of the board instead plug into the Line in TRS jack so that you don't choke your signal down with the microphone preamps in the board.
Makes sense to me but I haven't heard of this before.
Any thoughts??

 

[mambo4]

I'm guessing that was their "simplest solution" to your concern.

I'm sure more expert opinions will correct me , but as I understand it, getting your bass signal out of hi-z unbalanced 1/4" into a low-Z balanced XLR is the whole point of a DI.
So running the signal into the 1/4" input on the board must defeat the purpose?

 

[lowfreqgeek]

I'm guessing that was their "simplest solution" to your concern.

I'm sure more expert opinions will correct me , but as I understand it, getting your bass signal out of hi-z unbalanced 1/4" into a low-Z balanced XLR is the whole point of a DI.
So running the signal into the 1/4" input on the board must defeat the purpose?

This actually makes a lot of sense. The 1/4" input is balanced, and it's usually about 10k ohms, vs. anywhere from 600-2000 ohms on the mic preamp. It is a line-level input, which is ideal if you're connecting a line-level source, i.e. most bass amp DI outputs. It potentially keeps you from having to attenuate and then gain the signal again to get the proper gain structures. Just because it's 1/4", doesn't mean it's "high-Z", only that they use a different connector.

However, it depends entirely on the DI and output level and gain available, etc. If you use something like a Radial JDI, with it's 22dB attenuation, and a low-output bass, you may run into gain issues. It also depends on how clean the mic preamps are, and how much they alter the signal ("character").

It's not a fool-proof solution, but it'll work most of the time, and it's sure to be a good alternative with a line-level output such as most amp DIs. I know that my SWR Bass 350 DI sounds fabulous, but it's too hot for the XLR mic inputs on my old Line6 UX2. I haven't tried it on my RME Fireface, though. Will have to do that...

 

[Jimbob Jones]

A/B the two options and see for yourself. I prefer the sound of my (passive) DI, but YMMV.