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Preamp bypass

PostPosted: Wed Sep 25, 2019 3:24 pm
by Phil.c
I have had a Focusrite ISA 430MkI for about fifteen years, I rarely us it exept for DI'ing an instrument, apparently the pre amp is supposted to be very good but if it's used for say, a mic and then going into the d8b, both preamps are used?

If the ISA's preamp is better than the d8b's then the question is, how to bypass the d8b's preamp, I read somewhere that this could be done by removing the earth? From the XLR feeding the d8b, any input with this?

Re: Preamp bypass

PostPosted: Wed Sep 25, 2019 5:40 pm
by Crash
I use the Alt I/O slot with an analog card for that sort of thing. That seems the cleanest way in as to avoid a mic pre or line amp on a channel.

Re: Preamp bypass

PostPosted: Wed Sep 25, 2019 9:58 pm
by Phil.c
Question is.....how much better is the ISA 430 than the d8b.......if it is?

Re: Preamp bypass

PostPosted: Wed Sep 25, 2019 10:22 pm
by Crash
Phil.c wrote:Question is.....how much better is the ISA 430 than the d8b.......if it is?


Don't know. I've never used one of those. I would venture to guess that it's probably more different than better. I find the d8b pres to be kind of dark to neutral, which can work with some mics and not others. Just a different color crayon in the box.

Re: Preamp bypass

PostPosted: Fri Sep 27, 2019 5:43 am
by Bruce Graham
Hey Phil;

On channel 1-12, if you use the Insert Return. That should post pre-amp.

The level should be -10dBu, but could be 0dBu. I don't have a a block diagram at the moment to say for sure.

Channels 13 to 24 your hooped, as there are no inserts.

You can unbalance your pre-amp out by taking Pin 3 to ground.

Or as Crash says.

Hope that helps.

Bruce

Re: Preamp bypass

PostPosted: Fri Sep 27, 2019 9:01 am
by Phil.c
Thanks all, worth a try.

Re: Preamp bypass

PostPosted: Fri Sep 27, 2019 8:46 pm
by Old School
Hi all,
I'm glad you guys brought this up, I've always wondered if there was a way to bypass the mic preamps and I'm going to try these methods and see if my external mic pres are any better than the D8b's. Thanks guys!

Have a blessed day,
Mike W.

Re: Preamp bypass

PostPosted: Sat Sep 28, 2019 12:00 am
by arjepsen
I think I'm missing something here due to being a total noob at mixing, but since the mic preamps are only on channel 1-12, wouldn't it work to just use channel 13-24?
Or use the optical out of the focurite into channel 25+? (of cause presuming you have optical cards equipped).

Re: Preamp bypass

PostPosted: Sat Sep 28, 2019 1:40 am
by Bruce Graham
Hey Anders;

Generally we don't want to have more than one preamp (processor) in the signal path. Even though ch 13 to 24 don't have mic pre's it does have line level preamps. thus possible addition noise and "distortion".

Most would try to have the preamp output directly in the channel of the recorder they wish to record onto, thus bypassing all processing in the console and recording just the signal source with just one processor. The outboard preamp.

The way Crash has suggested is the easiest to do.

Hope that helps.
Cheers
Bruce

Re: Preamp bypass

PostPosted: Sat Sep 28, 2019 12:44 pm
by arjepsen
ok, thanks :-)