commanderberti
Well-known member
What are your experiences with what the last dB of noise improvement brings? PSU filters, special capacitors, transformers, which tubes... I'm grateful for all your tips!! Thanks
Build a low-noise, high-quality tube microphone
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RuudNL
Well-known member
A good tube! (The quality of tubes nowadays isn't what it used to be...)
commanderberti
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thanks, what tubes ecc83 can you recommend
LevinGuitar
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A good capsule too, some of the cheap ones can be slightly noisy.
I remember I was amazed of the silence more than of the sound when I tried for the first time a real K49 in mint condition.
I remember I was amazed of the silence more than of the sound when I tried for the first time a real K49 in mint condition.
..basically, the ECC83 is not suitable as capacitor microphone front end, grid leak and miller capacitance are prohibitive..
The reason the chinese started using it for mics was most probably just that they could get very-cheap "only-one-half-working" ecc83's, rejects from current production (check the original tube in there - most of the time the "other half" of the mounted dual triode is defective).
/Jakob E.
The reason the chinese started using it for mics was most probably just that they could get very-cheap "only-one-half-working" ecc83's, rejects from current production (check the original tube in there - most of the time the "other half" of the mounted dual triode is defective).
/Jakob E.
commanderberti
Well-known member
which tube(circurit) do you prefer?
How quiet do you really need a tube to be? I personally use tube mics for their coloration which starts to show at high-ish SPL. If you use a tube mic at low SPL where noise is starting to play a role you don't really get much of the tube goodness. My approach is FET for low noise, Tube for louder stuff where these mics really shine. Unless you record something with crazy dynamic range. I feel when people talk about tube mics noise as an issue it's where it becomes really obvious, where you clearly hear the noise in the recording. Couple of db in noise floor difference shouldn't be a deal breaker.
I am also a synth guy, and we use noise as an enhancement. What is a Juno 6 without it's noisy chorus? There's something nice about little bit of noise, but that's just me.
rogs
Well-known member
A good example of a nice bit of extra noise is the key click and generator 'leakage' on a Hammond organ....
Laurens Hammond himself spent years trying to minimise those things -- only for modern 'clones' of the original tonewheel organs to actually add these noises back in as a feature ......
You can 'dial it out' these days if you want, but it's not the same without the extra 'noise'....
The newest Yamaha clone even allows you to deliberately introduce hiss into the simulated Leslie amplifier..... just like the original
(it's a fully adjustable hiss level now of course!
)
RuudNL
Well-known member
IMHO the ECC83 (12AX7) is the worst tube to use in a condenser microphone.
Personally I have good experiences with the EH EF86 and the Russian 6SB6-V.
(I even replaced the original tube in my Neumann U67 reissue with an EH EF86, resulting in a lower noise floor)
Personally I have good experiences with the EH EF86 and the Russian 6SB6-V.
(I even replaced the original tube in my Neumann U67 reissue with an EH EF86, resulting in a lower noise floor)
Marik
Well-known member
Here is a more or less complete list of the tubes in more or less common tube mics.
http://audiotubes.com/mictubes.htm
The only omissions I can think of are C3G (Pegasus mic), 6S31B, and 5842/417A. Some tubes might look unusable--for example aforementioned 12AX7. Frame grid tubes (like 6922, or 6N1P) might look questionable, but then it is rather about implementaion. In general, it is better to look for the tubes with lower mu, lower Rp and higher transconductance. This allows you to use lower ratio transformers--it is easier to make them well in comparison to high (10:1--12:1) ratios.
If your goal is low noise then you better use jFets. Another way is making a first stage on jFet followed by a tube. This way you will take a good care of tube grid leak problems, as well. You could also use jFet as a lower shoulder of a cascode and then a frame grid tube on top--this arrangement will make perfect sense.
Hope it helps.
Best, M
http://audiotubes.com/mictubes.htm
The only omissions I can think of are C3G (Pegasus mic), 6S31B, and 5842/417A. Some tubes might look unusable--for example aforementioned 12AX7. Frame grid tubes (like 6922, or 6N1P) might look questionable, but then it is rather about implementaion. In general, it is better to look for the tubes with lower mu, lower Rp and higher transconductance. This allows you to use lower ratio transformers--it is easier to make them well in comparison to high (10:1--12:1) ratios.
If your goal is low noise then you better use jFets. Another way is making a first stage on jFet followed by a tube. This way you will take a good care of tube grid leak problems, as well. You could also use jFet as a lower shoulder of a cascode and then a frame grid tube on top--this arrangement will make perfect sense.
Hope it helps.
Best, M
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LevinGuitar
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I would add EC70 made by Mullard and EF762 by RWN/RFT to the best audio tubes. For now that were the nicest tubes I found when using with grounded cathode. Still not same as AC701, but quite closer than the rest of the famous subminis.
JeffKall
Well-known member
I absolutely concur !!!
If the EF86 was the choice of Microtech - Gefell (who IMHO is the REAL contemporary Neumann) and Dirk Brauner … who am I to argue ?
rock soderstrom
Tour de France
Gefell used EC92 and such, Neumann used EF86 (u67)
.. Gyraf G7 was EF86 also..
.. Gyraf G7 was EF86 also..
JeffKall
Well-known member
The flagship Microtech Gefell CMV 563/M 7S tube microphone uses the EF86 … as do others (see the complete list from the @Marik post in this thread) including the M 92.1S and M 990, which wires the pentode as a triode …Gefell used EC92 and such, Neumann used EF86 (u67)
.. Gyraf G7 was EF86 also..
Many of Georg Neumann’s descendants returned to work alongside members of the Kuhnast family … who were some of Neumann/Gefell’s best design engineers … when Georg Neumann GmbH was purchased by Sennheiser Electronic GmbH in the early 90’s … largely voiding the direct influence of the Neumann family and their extended family (Kuhnast) of historical technical advisors on Neumann microphones …
While not sharing the name recognition of Neumann … many music engineers … at least from my era … believe if you want a contemporary Neumann … buy a Gefell …
I had the pleasure of working with a matched stereo pair of Gefell M 930’s in ORTF configuration which produced some of the most beautiful stereo imaging I have ever heard on grand piano and strings (not to take anything away from the Decca Tree) …
References for further reading:
The History of Microtech Gefell
https://vintageking.com/blog/2021/07/buyers-guide-microtech-gefell/amp
https://en.wikipedia.org/wiki/Microtech_Gefell?wprov=sfti1#
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rock soderstrom
Tour de France
Hey Jeff, don't get me wrong, Microtech Gefell (GmbH) builds very good microphones and of course has a Neumann heritage. Unfortunately, the quality has not been consistently high over the years. Like many other GDR companies, VEB Microtech Gefell suffered from the (absurd) political system, lack of materials and the economic restrictions imposed by the Iron Curtain. Today, however, they are once again producing high-quality microphones, no doubt.
Is there any real evidence for the statement:"Many of Georg Neumann’s descendants returned to work alongside members of the Kuhnast family … who were some of Neumann/Gefell’s best design engineers … when Georg Neumann GmbH was purchased by Sennheiser Electronic GmbH in the early 90’s … largely voiding the direct influence of the Neumann family and their extended family of historical technical advisors on Neumann microphones …"?
This is the first time I have heard that "many" Neumann developers and specialists moved to Gefell, a town of just over 2000 inhabitants, from Berlin after the fall of the Wall. They would certainly have been noticed. Have you ever been to Gefell?
I'm very interested in the historical development of German (east and west) industrial history with a focus on electronics, optics and broadcast technology and enjoy researching on this topic.
We can do a source comparison, maybe I've overlooked your new information, but I'm not actually aware of it.
Of course, I don't know everything there is to know about this topic and am happy to receive any new input. But I think the statement"Microtech - Gefell (who IMHO is the REAL contemporary Neumann)" is misleading, as there are two independent brands. How can Microtech Gefell be the real Neumann after all this time? Neumann is Neumann and Microtech Gefell is now Microtech Gefell. I don't understand where this strange transfiguration of reality comes from? Nobody in Gefell would claim that they are the real Neumann. Why should they? They are proud of their work, brand and their origins!
Cheers!
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JeffKall
Well-known member
Hey Jeff, don't get me wrong, Microtech Gefell (GmbH) builds very good microphones and of course has a Neumann heritage. Unfortunately, the quality has not been consistently high over the years. Like many other GDR companies, VEB Microtech Gefell suffered from the (absurd) political system, lack of materials and the economic restrictions imposed by the Iron Curtain. Today, however, they are once again producing high-quality microphones, no doubt.
Is there any real evidence for the statement:"Many of Georg Neumann’s descendants returned to work alongside members of the Kuhnast family … who were some of Neumann/Gefell’s best design engineers … when Georg Neumann GmbH was purchased by Sennheiser Electronic GmbH in the early 90’s … largely voiding the direct influence of the Neumann family and their extended family of historical technical advisors on Neumann microphones …"?
This is the first time I have heard that "many" Neumann developers and specialists moved to Gefell, a town of just over 2000 inhabitants, from Berlin after the fall of the Wall. They would certainly have been noticed. Have you ever been to Gefell?
I'm very interested in the historical development of German (east and west) industrial history with a focus on electronics, optics and broadcast technology and enjoy researching on this topic.
We can do a source comparison, maybe I've overlooked your new information, but I'm not actually aware of it.
Of course, I don't know everything there is to know about this topic and am happy to receive any new input. But I think the statement"Microtech - Gefell (who IMHO is the REAL contemporary Neumann)" is misleading, as there are two independent brands. How can Microtech Gefell be the real Neumann after all this time? Neumann is Neumann and Microtech Gefell is now Microtech Gefell. I don't understand where this strange transfiguration of reality comes from? Nobody in Gefell would claim that they are the real Neumann. Why should they? They are proud of their work, brand and their origins!
Cheers
@rock soderstrom …
Thank you for your reply …
I should definitely be more specific regarding the expression of my opinion based on accounts and stories I had read and also heard amongst engineers in Los Angeles on how Georg Neumann had chosen Gefell as his place of relocation during the war and how he nurtured and built up Georg Neumann & Company Gefell with his technical director Erich Kuhnast and legal adviser only referred to as Mr Drechsler, who both accompanied him to Gefell from Berlin … as recorded in the Vintage King “The History of Microtech Gefell”
“Georg Neumann is best known for his industry-standard Neumann microphones, but when the original factory was damaged during WWII, he relocated from Berlin to Gefell. In Gefell, he began creating microphones with his technical director Erich Kühnast, his legal adviser Mr. Drechsler and a small team in an abandoned textile factory. After the war ended, Georg Neumann returned to Berlin, but continued making microphones at the Gefell factory under the name of Georg Neumann & Co/Gefell.
With Sennheiser purchasing Neumann in the early 1990s, Gefell and Neumann would remain separate entities. Georg Neumann's descendants would come back into the fold at Gefell and join members of the Kühnast and Drechsler families in leading the company into a new era.”
I likely took too much liberty using the word “Many” to describe the number of Georg Neumann’s descendants who returned to Gefell after the sale of Georg Neumann GmbH to Sennheiser in 1991 …
My sincere apologies for the confusion, sir !
But I will stand with my engineer peers, who felt that the sale of Neumann to Sennheiser was detrimental to Neumann … and I frequently heard the statement that IF someone wanted a true Neumann after the sale to Sennheiser … they should buy a Gefell !!!
Kind of similar in prevailing attitude among Fender purists, who refused to buy the CBS Fender product after Leo Fender sold his interest to CBS in the early 70’s …
The Wikipedia post refers to a “Sound On Sound” magazine Microtech Gefell M930 review article written by Hugh Robjohns that calls attention to Gefell carrying on the work of capsule building as specified by Georg Neumann:
“As a January 2004 Sound on Sound article stated: "Currently under the technical supervision of Kühnast's son, Microtech Gefell still produces the M7 capsule in exactly the same way Georg Neumann taught the elder Kühnast in the 1940s — hand drilling each hole in the backplate, making the PVC membrane, and gluing it all together by hand just as Neumann specified!"
“Robjohns, Hugh; "Microtech Gefell M930"; Sound on Sound January 2004”
I agree that Gefell definitely has ridden a quality roller coaster during its VEB era … but as you pointed out they are once again reclaiming their quality … (the same could be said for Fender in its post CBS era) …
Again … my sincere apologies if my opinion caused any unintentional confusion !
Best Regards !!!
Referenced Sources for the Wikipedia article:
https://en.wikipedia.org/wiki/Microtech_Gefell?wprov=sfti1#
Sources
- "Microtech Gefell 75 Year History"; https://web.archive.org/web/20040502160450/http://www.microtechgefell.de/eng/history/HistoriePDF/E_History Microtech Gefell _pdf.pdf
- Cucoo, Jeremy; "Microtech-Gefell M296"; Recording.org;
- "The History of Microtech Gefell"; Mercenary Audio; https://web.archive.org/web/20070914105604/http://www.mercenary.com/hiofmige.html
- Robjohns, Hugh; "Microtech Gefell M930"; Sound on SoundJanuary 2004; http://www.soundonsound.com/sos/jan04/articles/microtechgefell.htm?print=yes
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