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Noisy Mic Issue

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Re: Noisy Mic Issue

Postby Hugh Robjohns » Fri Jun 12, 2020 6:52 pm

Glad it was an easy restoration... Yes, a new valve would be a sensible next step.
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Re: Noisy Mic Issue

Postby blinddrew » Fri Jun 12, 2020 8:56 pm

So is a 6072 the same as a 12AY7 then? Or is there a further aspect I should consider? And is worth spending more than the one Dave identified in his initial response?
This is not, as you may have guessed, an area of my expertise! ;)
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Re: Noisy Mic Issue

Postby Hugh Robjohns » Fri Jun 12, 2020 9:04 pm

Yes, the 6072 is the equivalent of a 12AY7... But there's no shortage of pukka 6072As.

https://www.watfordvalves.com/search.asp?search=6072a&Submit=Search

...and other suppliers are available.

But not all 6072As are built as well and accurately as others.
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Re: Noisy Mic Issue

Postby blinddrew » Fri Jun 12, 2020 9:07 pm

Ok, so I don't need to be looking for something silly and esoteric then.
Excellent. Payday on monday, I shall place an order.
Thanks all. :)
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Re: Noisy Mic Issue

Postby ef37a » Fri Jun 12, 2020 10:22 pm

Forgot about Watford Hugh!

The 20 quid 6072A 'Harma' seems a decent bet for the money and at least you will have a reference. If it is not at least AS quiet as the original bounce it back!

Maybe record the noise?

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Re: Noisy Mic Issue

Postby blinddrew » Fri Jun 12, 2020 10:50 pm

Cheers Dave, will test and record when I get it.
Thanks
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Re: Noisy Mic Issue

Postby blinddrew » Tue Jun 16, 2020 8:48 pm

New valve fitted and noise is now down to similar levels as my sE2200a.
And a quick check with a couple of mics shows that the massive suck out at 5kHz, which I've only just noticed, is, in fact, just my voice.
ho hum
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Re: Noisy Mic Issue

Postby Hugh Robjohns » Wed Jun 17, 2020 4:02 pm

blinddrew wrote:New valve fitted and noise is now down to similar levels as my sE2200a.

Most excellent. :-)

And a quick check with a couple of mics shows that the massive suck out at 5kHz, which I've only just noticed, is, in fact, just my voice.

You need one of those mics with a big presence peak at 5kHz then... :lol:
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Re: Noisy Mic Issue

Postby CS70 » Wed Jun 17, 2020 5:00 pm

I was just gonna write “sounds like a loose wire” when I read the end of the thread. :-)

Have you checked that when you reassembled the chassis you re-tightened the screws as they were?

Some time ago the helpful chaps here helped me to solve a noise problem due to a screw that was not touching the chassis while it should have, creating a grounding issue. Long shot but..
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Re: Noisy Mic Issue

Postby blinddrew » Wed Jun 17, 2020 5:14 pm

I'm pretty sure it's fixed, i just have a hole in my voice at 5k.
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Re: Noisy Mic Issue

Postby Tim Gillett » Wed Jun 17, 2020 10:04 pm

blinddrew wrote:I'm pretty sure it's fixed, i just have a hole in my voice at 5k.

Drew, I've heard your voice on recordings youve posted and on this mic test. Yours just sounds like a normal voice to my ears. I'm not even sure anybody can have such a trough in their voice. Yes loudspeakers, headphones, amps, mics, recordings etc , but voices? We talk about the tried and true technique of using our voice to test the flatness of a mic or speaker's response. But the other way round? What do people think?
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Re: Noisy Mic Issue

Postby Mike Stranks » Thu Jun 18, 2020 9:16 am

Tim Gillett wrote:
blinddrew wrote:I'm pretty sure it's fixed, i just have a hole in my voice at 5k.

Drew, I've heard your voice on recordings youve posted and on this mic test. Yours just sounds like a normal voice to my ears. I'm not even sure anybody can have such a trough in their voice. Yes loudspeakers, headphones, amps, mics, recordings etc , but voices? We talk about the tried and true technique of using our voice to test the flatness of a mic or speaker's response. But the other way round? What do people think?

I've been squirting the human voice through either monitoring or PA speakers for all of my adult life.

I used to be quite surprised at how much EQ some voices needed to sound 'good'/'normal'. In particular, a friend of mine who was small and compact and didn't have a deep voice needed huge amounts of cut in the lows and mids. And it's just as true in other parts of the frequency spectrum for other voices - boosts as well as cuts.

I can't comment on Drew's voice specifically, but it seems perfectly possible to me. (And no, I don't want a sample so we can judge for ourselves.)

And I do hope we can keep this 'light' without diving down endless rabbit holes, citing various YouTube videos and/or Internet articles and constantly adopting an 'Ah! Yes, but...' tone. ;)
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Re: Noisy Mic Issue

Postby blinddrew » Thu Jun 18, 2020 9:48 am

I'll test a few mics and share the results, it'll only take a couple of minutes and i'm curious myself.
But it'll be a couple of days, so hold your horses 'til then. ;)
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Re: Noisy Mic Issue

Postby blinddrew » Sun Aug 02, 2020 10:40 am

Hmmm. Totally forgot to do the tests but may be doing so anyway as I think I may have mis-diagnosed the original issue. I'm beginning to wonder if it's actually as issue of output level rather than noise per se. Will post a couple of files in a bit once I've got some comparable tests done.
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Re: Noisy Mic Issue

Postby blinddrew » Mon Aug 03, 2020 9:04 pm

No files because I forgot to export them, but I have narrowed it down to a) it definitely needed a new valve last time, but also b) the power supply box is humming at about 150Hz (with a little resonance at 225).
If you stick your ear up against it you can pretty clearly hear it but it's then getting into the recorded signal as well even if the microphone is a long way away. Putting a couple of notches on the eq at those frequencies can remove it but unfortunately that's in a pretty critical area for my voice and leaves it sounding ugly.
Which is a bit vexing.
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