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Author Topic: Elam 251 getting Noisy, i think...  (Read 7203 times)

Rudimenta

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Elam 251 getting Noisy, i think...
« on: February 09, 2012, 03:22:37 am »

HI All,

Tried to register on this forum a couple times but somehow never got the activation mail. Finally figured out that they where hold back on server level. Anyway fixed.

Ok so i got an original Elam 251 E, so with the 6072 tube. I am having the feeling the noise is increasing over the last few months. I dont know if this is really true because i did change preamps, but when connecting with the old pre i got the same feeling. I know these are not the most quiet mics for noise floor concerned, but maybe somebody can give me some pointers on what should be acceptable and not acceptable. Maybe the Tube is getting old (which i hope the case is) so i can just replace it. If this is it where to get a good one, which supplier? Because the ones on Ebay... lets just say with this kind of mic i dont want to take any risks, seems they are faking everything nowadays...

Cheers!
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klaus

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Re: Elam 251 getting Noisy, i think...
« Reply #1 on: February 09, 2012, 01:22:12 pm »

If I understand your post correctly, you DID substitute mic pres? If that is the case, we can concentrate on troubleshooting the mic system. Here is the flow chart I use when I analyze noise in tube mic systems:

1. All voltages from the power supply correct (6.1-6.3VDC heater, 120VDC B+)? If yes, then:

2. Tube substitution with a GE 5-Star 6072 tube. Nothing but this specific model is prescribed for these mics. Noise still there? Try one more of these tubes, to lower the possibility that you had two new, bad tubes in a row. Noise still there?

3. Capsule investigation: membranes still fully tensioned under polarization voltage, or is there excess contamination or tension loss?

Usually these three steps will give you the answer why your ELA M is noisy.

By the way: an original, fully set up ELA M 251 with a well-selected 6072 is not particularly noisy. It should only be one or two dB noisier than a (well set up) U47.
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Klaus Heyne
German Masterworks®
www.GermanMasterworks.com

Rudimenta

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Re: Elam 251 getting Noisy, i think...
« Reply #2 on: February 09, 2012, 02:11:37 pm »

Hi Klaus,

Thanks for responding:

Yes indeed i moved to a Neve 1073, however the API when i connect back is also to my idea sounding more noise then before. So I am almost sure that it has increased from the mic side.

I dont have a volt tester at hand (we are on 220 here) Ill get a voltage meter this weekend and test. On a side note, the voltage selector on the power supply does not have indicators, could it be set to 240 by mistake... and that be the cause, dont think so anyway.

I am currently living in a country where i can not obtain tubes from any stores/suppliers. I do have regional dealer i could ask, which ill do, if you have any other suggestions on where to buy a GE 5star 6072, please let me know, maybe via pm if you dont want to advertise. The tube in the mike is indeed a 5 star GE.

My noisy remark was more in relation to a lets say modern day Neumann.
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klaus

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Re: Elam 251 getting Noisy, i think...
« Reply #3 on: February 09, 2012, 02:31:17 pm »

It is important that you have the supply voltages of a tube mic checked periodically. Especially when we are talking about the most expensive serially manufactured tube mic in the history of tube mics!

Not only the tube, but the irreplaceable capsule in particular can be greatly harmed if these voltages are off. 

If you use the mic in a 220VAC county, you need to set the voltage selector at the bottom of the ELA M950EC power supply to 220V. Then you need to check, and if necessary, adjust, to the DC voltages I gave you in my last post.
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Klaus Heyne
German Masterworks®
www.GermanMasterworks.com

Rudimenta

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Re: Elam 251 getting Noisy, i think...
« Reply #4 on: February 20, 2012, 11:43:01 am »

voltage is ok.

Now where to get tubes, anybody have a suggestion?
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J.J. Blair

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Re: Elam 251 getting Noisy, i think...
« Reply #5 on: February 20, 2012, 06:18:11 pm »

I've used Christian Whitmore for the last bunch of tubes I had to source.  I'm not sure if he has any 5 star GE 6072s in stock, but I would start with him.  He has a great collection and is very knowledgable.  You can contact him at proudiotubes (at) aol.com. 

I've sourced many of these myself on eBay, and the results are a little hit and miss, at leads in terms of noise.  Some are dead quiet, and some are the tiniest bit hissy, but I've not found any NOS 5 star 6072s on eBay that were unusable. 

Klaus, have you ever tried any of the orange label Raytheons?
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klaus

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Re: Elam 251 getting Noisy, i think...
« Reply #6 on: February 20, 2012, 07:15:28 pm »

I have not. I generally have been so very satisfied with GE's Five Star (as you indicated, easily one of the most reliable tube models for microphone applications- in difference to ANY other 6072 I have investigated in the past) that I did not see a need for a quest to find anything better. But  if you tell me that the Raytheon is better than the GE I will test one out to confirm.
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Klaus Heyne
German Masterworks®
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Rudimenta

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Re: Elam 251 getting Noisy, i think...
« Reply #7 on: February 20, 2012, 09:27:28 pm »

Thanks i start with sending him an email.

I rather buy from a guy that knows what he is selling (and pay extra for that) then do the gambling on ebay.

Cheers!
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Rudimenta

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Re: Elam 251 getting Noisy, i think...
« Reply #8 on: February 22, 2012, 07:36:48 am »

Thx Blair Chris has been more then helpful and will be sending me 3 tubes ;)
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klaus

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Re: Elam 251 getting Noisy, i think...
« Reply #9 on: February 22, 2012, 06:12:31 pm »

Please report your noise findings on all three tubes!

Thanks,
KH
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Klaus Heyne
German Masterworks®
www.GermanMasterworks.com

Rudimenta

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Re: Elam 251 getting Noisy, i think...
« Reply #10 on: February 28, 2012, 08:31:38 pm »

Hi Klaus,

I will, they should be arriving tomorrow. He send me the following (his description):

  The 1970s-1980s version has the softest sound because the focus is not as sharp as the other versions.  Telefunken USA uses a similar tube in their 251 re-issue, as does AKG in their C-12 re-issue. 

  The mid-1960s version is the most clear and crisp sounding GE 6072.  The highs are a little more present and the transient response is the sharpest of the GE types. 

  The 1950s through early 60s (aka "triple-mica") version is similar to the above but with a slightly softer high frequency response and just a little more body in the low-mids.  The difference is not big though. 

He burns them for 100 hours and preselects, seems like he has big stock.

But before i open up the microphone. Could you let me know the best way to proceed, do you have a post on this subject already? It would be my first tube change and opening up of the microphone i have to do myself and like to follow the right steps. Last time it was opened was when i bought it. However where i live now there are no tech's around..

Cheers,
Ruud
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saxmonster

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Re: Elam 251 getting Noisy, i think...
« Reply #11 on: April 23, 2012, 01:09:57 pm »

How does the new tube sound and how much was it?  I am looking at build a 251 clone with this tube but was wondering how this tube sounds.

-Scott
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MrChick

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Re: Elam 251 getting Noisy, i think...
« Reply #12 on: November 13, 2016, 02:21:07 am »

Hi all. I'm having a problem with a 251V (original CK12). It have a lot of noise and low signal but only in cardioid. In omni and fig8 it works fine. The mic came from USA so I've changed the PSU at 220V.

Any idea what is happening, what must I do?
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klaus

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Re: Elam 251 getting Noisy, i think...
« Reply #13 on: November 13, 2016, 12:15:15 pm »

What is  "251V"? If it is a copy mic, please contact the manufacturer.

If it is a vintage, original AKG-made ELA M251, and the noise only appears in cardioid, I'd suspect capsule contamination, as the front diaphragm gets lots more spit exposure which attracts air-borne contaminants which, in turn, eventually lowers the impedance of the capsule and discharges with noisy side effects.

Do not attempt to clean the capsule yourself. It will more often than not destroy it.
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Klaus Heyne
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MrChick

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Re: Elam 251 getting Noisy, i think...
« Reply #14 on: November 13, 2016, 03:56:26 pm »

Thank you Klaus. This is a early 2000 251e  tele USA made with vintage parts (NOS original CK12). I guess the problem is in the capsule too. Today the mic has worked fine all day, though. Can you recommend a European mic tech for overhaul it?
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