Silly question regarding xlr to 1/4" cable

Lestratcaster

Someone told me I shouldn't be using an xlr to 1/4" cable for a microphone input, say an SM57. Is there any truth in this? That I should be using xlr - xlr? Is this because the signal wouldn't be a balanced one?

Or can I actually use a female xlr to 1/4" jack into an interface/mixer? I only ask as my mixer only has 1 xlr port for a vocal mic usually, so if doing anything with a backing track I need that port, if I was to use an SM57 say, to mic up either an acoustic guitar or guitar speaker would it better to do xlr to xlr?

mrkb

Is the 1/4” plug TRS or TS? If it’s TRS it will be balanced, if it’s TS it won’t be.

Lestratcaster

I haven't actually got one yet, just wanted to know if I can run a mic into say, the 2nd port of a mixer or would I need a mixer with 2 xlr ports.

mrkb

If the 1/4” input is balanced and the Mic doesnt need phantom power, then you can use a 1/4” input with a microphone. But that probably means the 1/4” input doesn’t have a Mic Preamp (as they are usually used on xlr inputs on the mixers I have), so might not give the best mic sound/gain structure.

Lestratcaster

Yeah this is what brought my question as 1/4" input doesn't have a preamp.

Lestratcaster

Just bringing up this thread again, someone said if I was to get an Sm57 and use an xlr to 1/4 I can use a passive DI box to convert to a balanced input to the mixer? I didn’t get the DI box function, would it act as a preamp as well?

maltingsaudio

In real terms it’s all about gain. A quarter inch input non balanced ie one ring on the Jack is usually line level not mic level so you need to up the gain on the channel to get a decent signal which usually introduces unwanted noise.  . If the input on your interface accepts a balanced signal then the quarter inch Jack will have two rings on it to be balanced but a normal Jack one ring will still work, and there should be no need to ramp the gain to get a decent signal. A Di box in the chain won’t make any difference it’s all about the input to the card.
To answer your particular question, an SM57 gives out a balanced mic level signal.  Using a quarter inch Jack with one ring , simply removes one side of the signal, it’s still at mic level although due to having one side of the signal removed is more prone to interference. Putting a Di box after the quarter inch one ring Jack cannot reproduce the signal that isn’t there in the first place.

Lestratcaster

Yeah I get that about balanced and unbalanced, I use balanced cables to go from my interface (Focusrite) out to my Yamaha HS8 monitors. The Focusrite accepts balanced inputs, so would it be a case of getting an xlr to balance 1/4 cable? And if the DI box is redundant will a preamp thing such as a Cloudlifter/FetHead box be more suitable? They're supposed to boost the input on dynamic mics (in this scenario an SM57)

*EDIT having said that those pre amp boxes only have an XLR input which wouldn't be much use if its an xlr - 1/4" cable

maltingsaudio

Yes only use balanced cables from mic  to the focusrite all should be good and no need for an outboard preamp into the computer, all gains can be matched in software.

Lestratcaster

A reminder I use a mixer to do live stream stuff, and that mixer only has 1 xlr input which is used for a vocal mic so I haven't got another way of getting an xlr cable into the signal. I use another input for backing music so its 3 really.

steamabacus

It might help to know exactly what interface you have - it sounds like it might be a Focusrite Solo (one xlr mic input, one 1/4" line/instrument input).

The second input cannot be 'converted' to balanced.

What you would need is an external mic pre-amp with a line level output. You could then plug the SM57 into the pre-amp's mic-level balanced XLR input (with an XLR-XLR cable) and plug the pre-amp's line-level output into the Focusrite interface (set to 'line') with a standard 1/4" cable. Balance the pre-amp output level with the Focusrite's Gain control (and any output level control on the mic pre-amp).

Lestratcaster

It’s the 8i6 but windows 10 only picks up analogue 1+2 ports on the front and as mentioned before I use 3 inputs (hence why I need the mixer). Vocal mic, guitar (usually plugged in with a 1/4” from my Kemper if on electric guitar) then backing track with a dual 3.5mm to 1/4 cable. Then main out of mixer into front two analogue ports of the 8i6

My main issue is when I want to use acoustic guitar mic’d up with an Sm57 there’s nowhere to plug it into with an xlr unless I get an external pre amp for it like you said.

steamabacus

I didn't see your last post until after I posted mine.

So what mixer exactly? It might be that the simplest solution is a new mixer with enough mic inputs?

Or could you put two inputs (1 mic, 1 backing music) via the mixer in mono into one of interface's input's and the second mic directly into the interface's second mic input?

steamabacus

Or, of course, can you get a 'computery' type (which isn't me unfortunately) to help you to get the interface working properly with Windows10 so you can use its line inputs for your mixer?

Lestratcaster

steamabacus said:

I didn't see your last post until after I posted mine.

So what mixer exactly? It might be that the simplest solution is a new mixer with enough mic inputs?

Or could you put two inputs (1 mic, 1 backing music) via the mixer in mono into one of interface's input's and the second mic directly into the interface's second mic input?

It’s the Alto ZMX52 compact mixer. Should really have got the 862 with 2 xlr inputs. 

For some reason when I use 2 separate inputs into the Focusrite it only comes out of one speaker side so might be something to do with stereo or mono output on the software control of the Focusrite.

maltingsaudio

steamabacus said:

It might help to know exactly what interface you have - it sounds like it might be a Focusrite Solo (one xlr mic input, one 1/4" line/instrument input).

The second input cannot be 'converted' to balanced.

What you would need is an external mic pre-amp with a line level output. You could then plug the SM57 into the pre-amp's mic-level balanced XLR input (with an XLR-XLR cable) and plug the pre-amp's line-level output into the Focusrite interface (set to 'line') with a standard 1/4" cable. Balance the pre-amp output level with the Focusrite's Gain control (and any output level control on the mic pre-amp).

Read the manual page 16 4.

Input 2 – 1⁄4” TRS jack socket for connecting instruments (unbalanced) or line level (balanced)

sources.

GAIN 2 – adjusts the gain for the line/instrument signal at Input 2. The gain control has a tri- colour LED ring as [2].

INST/LINE – Instrument/Lin

Lestratcaster

What if I got one of these transformer things?

https://www.gear4music.com/PA-DJ-and-Lighting/Shure-A85F-Line-matching-Transformer/33MC?origin=product-ads&gclid=EAIaIQobChMI-7qtjviW8QIV2trVCh1ftw_DEAQYASABEgL-IfD_BwE

looks like its meant to boost gain into a line input from xlr.

prowla

What's the issue with converting balanced (3-pin XLR) to instrument (2-pin jack)?

Danny1969

You can just reverse a passive DI box to match the low Z mic to a typical 10K ish line input.

Balanced connections on short runs aren't really necessary for the most part ..... in fact in some cases a short unbalanced signal chain will be less noisy than a balanced one because total noise  = circuit noise and noise picked up from cable and a differential opamp input circuit like the design in the Alto is noisier in design than a singled ended opamp circuit. 

Any more than a couple of metres though an electrically noisy environment though  and balanced will win out. 

The amount of gain needed on the desk depends entirely on the output of the mic's transformer and this depends entirely on the sound pressure level and how near it is to the source. Put it near a drum and almost no gain will be needed, for a soft spoken vocal quite a bit of gain, maybe 30 to 40dB 

Lestratcaster

prowla said:

What's the issue with converting balanced (3-pin XLR) to instrument (2-pin jack)?

Because a 1/4 line input doesn't have the desired preamp gain to drive the microphone to acceptable volume without hissing and feedback?

Lestratcaster

Danny1969 said:

You can just reverse a passive DI box to match the low Z mic to a typical 10K ish line input.

Balanced connections on short runs aren't really necessary for the most part ..... in fact in some cases a short unbalanced signal chain will be less noisy than a balanced one because total noise  = circuit noise and noise picked up from cable and a differential opamp input circuit like the design in the Alto is noisier in design than a singled ended opamp circuit. 

Any more than a couple of metres though an electrically noisy environment though  and balanced will win out. 

The amount of gain needed on the desk depends entirely on the output of the mic's transformer and this depends entirely on the sound pressure level and how near it is to the source. Put it near a drum and almost no gain will be needed, for a soft spoken vocal quite a bit of gain, maybe 30 to 40dB 

Any suggestions on a DI Box? Preferably not too expensive - less than £50?

"Reverse" meaning running it the 'wrong' way round so its the line input first? What sort of cables would I need from the SM57 then?