Focusrite 2nd vs 3rd Gen and others - help please

[DaveT]

@John_E

I assume the XLR outs I am dealing with on my amp and B7K and VT Bass DI are CONSUMER level and fine on any XLR input?

The 1/4" inputs let you run hotter than the XLR inputs. You can use an XLR to TRS cable.

These inputs 7/8 seem to take the hottest levels, but they kind of contradict themselves in this paragraph . . .

[howard]

@Koldunya

Instrument In: 1.5MΩ (1/4" of front combos with instrument selected)

This is a very typical Hi-Z impedance. the roland seems pretty low actually, I had not seen less than 1MΩ Hi-Z before. Should be fine though.

@DaveT

but they kind of contradict themselves in this paragraph . . .

Do you know if there is a standard for XLR line level, or even a typical range, for DI outs usually carrying an instrument signal? I am almost certain it would be instrument level or consumer line level but I have never seen a reference. Otherwise passive DI’s wouldn’t work.

Pro line level is +0 to +4dBV IIRC. Not 100% sure that directly maps to dBu but ISTR it’s close.

[DaveT]

@John_E

I assume the XLR outs I am dealing with on my amp and B7K and VT Bass DI are CONSUMER level and fine on any XLR input?

I didn’t look them all up, but if they are hot you can just turn them down on the output of the device (assuming that’s possible). The VT Bass DI is 0dB out, so you could run it into XLR 7/8.

From the VT manual:

From the Roland manual:

[John_E]

Ah, I can also flip the little switch to -20Db and not worry.

Darkglass says this…
Balanced XLR output for connecting the pedal to a microphone preamp, PA system etc.
So assuming its fine.

[DaveT]

@howard

Do you know if there is a standard for XLR line level, or even a typical range, for DI outs usually carrying an instrument signal? I am almost certain it would be instrument level or consumer line level but I have never seen a reference. Otherwise passive DI’s wouldn’t work.

Pro line level is +0 to +4dBV IIRC. Not 100% sure that directly maps to dBu but ISTR it’s close.

DIs are traditionally at mic level as they started passive. There’s nothing stopping a particular design from having more gain. Bass pedals with DI outputs are a good example and there’s no standard.

[DaveT]

@John_E

Ah, I can also flip the little switch to -20Db and not worry.

Yes, the only reason to run a hotter output is to have greater signal to noise ratio. If you don’t have noise, you don’t have a problem.

[DaveT]

@John_E

Balanced XLR output for connecting the pedal to a microphone preamp, PA system etc.
So assuming its fine.

It’s probably fine, but same answer. If it’s too hot try it on input 7/8.

[howard]

@DaveT

DIs are traditionally at mic level as they started passive.

Good to know, thanks!

@DaveT

There’s nothing stopping a particular design from having more gain. Bass pedals with DI outputs are a good example and there’s no standard.

Yeah that was my understanding and fear as well.

[DaveT]

@howard

Pro line level is +0 to +4dBV IIRC. Not 100% sure that directly maps to dBu but ISTR it’s close.

0 dBV = 1 Volt
0 dBu = 0.775 Volts (RMS value of 1 volt sine wave)

Pro audio levels are usually given in dBu. +4dB line out is usually +4dBu or 1.228 volts or 1.8 dBV

Consumer levels are usually given in dBV. -10dBV is 0.32 Volt or -7.8 dBu

Microphone levels are usually given as sensitivities as mV / Pascal or dBV / Pascal. Worst case mics could need 60 dB of gain. Gain is unitless.

[howard]

@DaveT

Worst case mics could need 60 dB of gain. Gain is unitless.

Yep. When evaluating mic preamps usually you see a tradeoff between the noise floor and the gain range. And once you factor in that huge gain needed for some mics, that -120dB noise floor doesn’t look so good. And so, there’s a lot of agonizing about -128dB vs (say) -131dB for the noise floor, which is actually a large difference.