Noise floor too high

[Robyboyd]

Hello,

I’m a new member from France. I have downloaded REW last friday in order to set up my speakers, altec VOT that I run in 3 ways.

I run REW througt Focusrite scarlett solo soundcard and dayton audio EMM6 XLR Mic ordered for the task.

Since the begining, I faced an issue that start to make me mad! I’m pretty sure that I did everything well to set up REW, but I face issue with the noise floor that is too high and make trouble with my metering.. It could be a not so strange issue if the noise floor was always wrong, but the thing is that the pb ALWAYS comes after (let’s say) the five first metering. I mean that everyday, since friday, I can have « good » noise floor and metering for around five minutes, and then, suddenly the noise floor appears and make any usable metering possible.

Each time I tried everything to take back the good noise floor value, from turn everything off, to reboot REW, disconnect cables, tried V5.19 and V5.20... but unfortunately nothing that solve the issue.

The only thing that « works » is to wait the day after, where again I’m able to make it run good 5´ before the pb appears, and so on...

It make me crazy!

Could you please help me to find what’s going wrong? I have very small knowledge in electronic, but this make me think that something could be wrong with a capacitor in the card or the mic (this because there is a question of time of good use before the noise floor arrive). Hope my thougts are enough clear as english is not my mother language.

Thx for your hell.

Br.

Arnaud.

 

[Robyboyd]

Thx for your help (wanted to say)

Br.

 

[DanDan]

Using DAW software, listen to your microphone. These very small diaphragm mics have a high noise floor, hiss. Turn up the gain, listen and meter. Leave it like that for hours to find out if it increases or not.
This should help you decide if the Mic and Interface are OK.

 

[Robyboyd]

Hello,
Thx for your reply. Yesterday I did a direct listening of the micro through the sound card (focusrite scarlett solo) with headphone. At the begining, no noise floor, and I could perfectly here the source (tv). After few linutes, the noise has incresed so I couldn’t here the tv signal in the headphone, just a kind of pink noise.
I’m pretty sure the issue comes from the mic, but if it possible, with the issue described, that could be the mic entry card that is deffeacted?

 

[DanDan]

paso y paso, step by step. Try the mic on the other mic input. Or try another mic on that same channel.

 

[Robyboyd]

Hello DanDan,

unfortunately, I have only one mic input and one mic... I sent it back to have another one. (sorry for the mistake in my previous mess. It was late in France when I wrote it).
Hope to ear you again!

 

[DanDan]

'Late in France'...... Netflix, Beer/Wine?.......
I am sorry to that you on the EU mainland have been hit so cruelly.
Did you send back the mic AND the interface? From your original post, yes I too suspect something like a capacitor, failing after time.....
If you still have the interface, try it without the mic.

 

[Robyboyd]

Ok, you are right, I dis some late post on forum, but obviously It is not the case here as I see that the sending post hour is in the good time zone...
No matter.
I kept the interface. What kind of test do you recommend? I should control the mic input, maybe I could connect any source with XLR connexion (without phantom supply!) instead of the mic and listen to it through headphone if it's ok?

 

[Robyboyd]

Do you think I can connect the headphone output of my preamp to the mic output of my scarlett to do the test?

 

[DanDan]

Testing is just pure cold logic, like an opposite to gambling. You need to test each item separately.
Do you have a separate preamp? You can run this separate preamp into a Line input of the Scarlett. You would also test the Scarlett preamp, removing the separate pre. But these are long shots. A preamp with no input or just a cable can be listened to ..... gain up high, hiss. If it gets worse after a while bingo. But it is far more likely to misbehave with an actual microphone drawing phantom power. Or an Active DI if you have one.

 

[Bernard]

unfortunately, I have only one mic input and one mic... I sent it back to have another one. (sorry for the mistake in my previous mess.

Hello Arnaud,
A french guy who thinks you were badly advised on the choice of the sound card can lend you a Presonus PRM1 to help you if it's a microphone problem.
How can we advise a device if we haven't tried it ourself?
I don't know how we can exchange by private mail on this site.

 

[Robyboyd]

Hello Bernard,
As we are both french, it’s pretty strange to exchange here in english
Why do you think that I was badly advised on the soundcard?

 

[Bernard]

Maybe one day you will want to study a new crossover and at that time you will need two line inputs.
It's strange that the failure always occurs after 5 minutes of operation. Does it happen again within the same time frame?
Do you use the PC on the mains?

 

[Robyboyd]

Hello Bernard,
I bought this sound card for crossover study. Why do you say I need two line input? I have two line output and I one line input for the mic. I think it’s ok.
Indeed, the failure occurs after around 5 to 10’. Yesterday, I plug my preamp to my soundcard, in the mic output. No pb. I pretty sure now that the issue comes from the mic. I sent it back in order to have an another one. Wait and see.

Br.

 

[Robyboyd]

Fyi I post about this on melaudia (french audiophile forum).

 

[DanDan]

"Yesterday, I plug my preamp to my soundcard, in the mic output. No pb. I pretty sure now that the issue comes from the mic. I sent it back in order to have an another one. Wait and see."
Bien Hercule, une autre affaire résolue.....

 

[Bernard]

DanDan,
Oh dear, rather Auguste Dupin or Inspector Lecoq than Hercules Poirot who was Belgian.

 

[DanDan]

Oops a pas faux........

 

[Robyboyd]

ok guys, but what is Kojak doing?