You are here

EFX12 - using insert with mic issue

All about the tools and techniques involved in capturing sound, in the studio or on location.

EFX12 - using insert with mic issue

Postby sameloop » Wed Jan 31, 2018 11:44 am

Hi. Strange problem - I have a Soundcraft EFX12, it’s pretty new and hasn’t given me any problems until now. I’m hoping it’s just ‘operator error’, but when I try and use a channel with a microphone (either an SM57 or AT 2030) and insert cable (running to an FX loop with various Moog pedals etc), I get almost no level on the mic - it’s like it’s running it pre-everything into the pedals. If I crank the gain up to almost full I get a small amount of signal but with nasty distortion.

If I remove the insert, the channel behaves as normal. If I use a line input with the insert, that also works as expected. I can’t work it out. It’s my understanding that an insert is post gain but pre fader/eq on these and pretty much all desks, so I just can’t see how I’m not getting a normal level.

I’ve tried various channels and get the same thing.

Any ideas?

Thanks.
sameloop
Posts: 2
Joined: Wed Jan 31, 2018 11:33 am

Re: EFX12 - using insert with mic issue

Postby Hugh Robjohns » Wed Jan 31, 2018 12:33 pm

sameloop wrote:... when I try and use a channel with a microphone (either an SM57 or AT 2030) and insert cable (running to an FX loop with various Moog pedals etc), I get almost no level on the mic - it’s like it’s running it pre-everything into the pedals. If I crank the gain up to almost full I get a small amount of signal but with nasty distortion. ... If I remove the insert, the channel behaves as normal. If I use a line input with the insert, that also works as expected.

The insert point is after the input stage preamp which handles both mic and line signals -- so the signal appearing at the insert point will be the same regardless of the actual type of channel source. This is assuming you set the channel gain structure for mic and line sources to provide the same signal levels on the meter when you PFL the channel(s).

So, when you say the inserts work with line sources but not mics there must either be some level of 'user-error' going on, or you're talking about different channels connected with different Insert cables and different FX pedals.... in other words something must be significantly different in the insert signal path, but you're overlooking that difference for some reason.

The way to resolve a problem like this is to simplify as much as possible, and then work logically through the signal path.

So, the likely fault options are:

    (a) You have a defective Insert Y-cable
    (b) You have a plugged the split ends of the Y-cable into the pedals the wrong way around (ie, the send is connected to a pedal output and the return to the pedal input -- which is easily done!)
    (c) The pedals can't handle the line-level input signal or are not able to operate at unity gain and are therefore returning too low a signal level into the insert return.

You can test the cable by setting the mic channel up as normal without the insert cable plugged in. Next, plug in the insert cable: at this point the channel should go quiet because the send/return plugs aren't connected to anything, and so the send signal is not getting back into the return path.

If you now touch the tips of the two send/return jack plugs together the channel should burst back into life. If it does the cable is good... if not, it ain't!

So... if you have a good insert cable, the next thing is to confirm the correct send/return connections. Although most desks use the tip-send/ring-return connection format some, inevitably, wire unbalanced inserts up the other way around, and in the same way some insert cables are labelled for the uncommon/incorrect arrangement!

To check whether you have a reversed send/return configuration, plug the Insert Return lead into the output of an FX pedal that you know works, and plug a guitar (or some other suitable device the input of said pedal to serve as an independent sound source.

You should then hear the guitar (or other source) passing through the pedal and straight back into the mixer channel via the Return connection. If necessary, adjust the output level of the FX pedal to achieve a similar volume through the mixer to that achieved previously during the mic channel test.

If it won't go loud enough, the pedal isn't suitable for use as an insert effect on its own -- you'll need something else in-line to boost its output signal level.

If you get nothing at all, you probably have the reversed send/return scenario so try swapping to the other side of the insert Y-cable and see if that works. If it does, the insert cable is labelled the wrong way around for your system configuration, so re-label it!

Having proven that the return side of the insert connection is working properly with the FX pedal, you can check the send side. Disconnect the guitar (or other source) and plug the Send side of the insert cable into the FX pedal instead. You'll probably need to adjust the pedal's input level downwards at this point because the insert Send level will probably be louder than the guitar used previously!

And hopefully, everything will now be working as required...

If not, come back and tell us more!

H
User avatar
Hugh Robjohns
Moderator
Posts: 21950
Joined: Fri Jul 25, 2003 12:00 am
Location: Worcestershire, UK
Technical Editor, Sound On Sound

Re: EFX12 - using insert with mic issue

Postby sameloop » Wed Jan 31, 2018 2:38 pm

Hi. Thanks so much for your very helpful and detailed reply.

I'm now feeling totally stupid for not checking my connections - it was a simple matter of things wired up the wrong way (that old chestnut!)

I'm using a Boredbrain Patchulator as my effects patch bay and you really have to concentrate on ins and outs with it - not the most helpful layout and graphics on that thing, to be fair to myself.

Still, problem solved in the way you suggested, which was to troubleshoot it properly (like I nearly always do!)

Must be having an off day...

Thanks again.
sameloop
Posts: 2
Joined: Wed Jan 31, 2018 11:33 am

Re: EFX12 - using insert with mic issue

Postby Hugh Robjohns » Wed Jan 31, 2018 3:58 pm

:thumbup: No worries -- we've all been there. Swear blind everything 's wired up properly, then spot the blindingly obvious cock-up after a cup of tea ! :lol: The Patchulator is an attractive thing in some ways, but I don't think it's anything like as easy to use as a traditional patchbay.

H
User avatar
Hugh Robjohns
Moderator
Posts: 21950
Joined: Fri Jul 25, 2003 12:00 am
Location: Worcestershire, UK
Technical Editor, Sound On Sound


Who is online

Users browsing this forum: ConcertinaChap