Home » R/E/P » Klaus Heyne's Mic Lab » Gefell UM70/MV692 combo -- fact or fiction?
| Gefell UM70/MV692 combo -- fact or fiction? [message #435185] |
Fri, 17 July 2009 19:01  |
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 Mike Jasper
Messages: 85
Registered: October 2006
Location: Austin, TX |
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I'm writing an article on the UM70/MV692 and thought I'd fly a few paragraphs here first since there are no such thing as editors anymore.
Does this seem accurate? Anything I'm leaving out? Appreciate the help.
<<<There are so many variations of these mics that people get confused. First, you have the MV 691, which is essentially the same as an MV 692 except no low cut or -10db pad. Also, the original models came with Tuchel connections, but you can get them converted to XLR (Andreas Grosser and Peter Drefahl in Germany are a couple of good men for for that job) or use a Tuchel to XLR cable. If you want to go back further, the original MV 690 required a power supply to work and the original MV 691 and MV 692 had no phantom power. That didn't come along until the MV 692 P48V version, although earlier versions could be converted.
Wait, there's more! Two types of no-longer-made MV 692s exist, the older RFT model and the newer Microtech-Gefell version. The latter comes with factory installed XLR connectors and an updated Microtech-Gefell logo. They were later replaced with the non-modular UM70S, which is essentially the same mic without a removable capsule. Capsules can get confusing, too. The UM70 capsule can be adjusted to cardioid, omni and figure 8, but there's also an M71 which is a cardioid-only large diaphragm capsule and an M70 capsule which is a small (or medium for you purists) diaphragm nickel capsule. There are several no-longer-made capsules that can still be found on Ebay -- M93 Far Field Omni, M94 Small Cardioid, M69 Near Field Omni
and M73 Shotgun.
There's also a tube version of the preamp, the MV 582, but I don't want to get into that at all. There's one more confusing aspect of these mics. The part that attaches to the capsule, the body or handle of the mic, is called the preamp -- not to be confused with the mic preamp you'll use to amplify the entire mic itself.
Further, the only place to get these mics properly serviced are in Germany. If you want your UM70 capsule reskinned, you have to either send it to Microtech-Gefell or Sigfried Theirsch. To repair or convert the preamp, you'll send it to either Gefell or Peter Drefahl or Andreas Grosser. The good news is that these mics can be be refurbished as good as new and -- likely because of the confusion -- good working mics can be found for $1000 or less.>>>
My goal is to clear up the confusion surrounding these mics. I'm not sure I'm really helping.
Jasper
SD mic shootout from Tape Op now online
http://www.proaudiobay.com/shootouts.html
"Where are the repair people in this country? Where have they gone? Currently, the state of microphone service availability in the US is an unmitigated disaster, especially in light of the fact that there has never been a boom in the history of recording mics like this."
-- Klaus Heyne
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| Re: Gefell UM70/MV692 combo -- fact or fiction? [message #435529 is a reply to message #435185 ] |
Mon, 20 July 2009 12:42  |
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Oliver Archut
Messages: 1165
Registered: April 2004 |
Platinum Member |
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Hello Mike,
not 100% true, I think best choice for you is to contact Mr. Thiersch, as far as I know he developed some of the MV 69x stuff.
There is the MV690, 691 and 692 were the 690 with several sub versions, mostly in respect to components used.
The 690 has no build in DC/DC converter so not all capsules will work/fit.
The 691 is the universal pre-amp that works for all capsules, but the quality spread due to east german/russian components is quite large, in my experience 2 out of 10 will work quite fine.
The 692 is an even bigger night mare than the Elam, due to its "peoples own" duro plast. Once broken there are no replacements... but the bigger problem is the op amp based electronics.
You point out the confusion on the model and sub versions, but in my view the biggest confusion is the idea that it will sound like Neumann, which it does not!
The 691 is a good chassis for a modification project, and even then in order to use all those capsules it is just a compromise, none of them sounds to their potential.
Also they do not use Tuchel connectors, they use an east german generic version.
The main sound of the 69x P48V conversion depends largely on how it is done, there are several circuits out there but not all work great.
Best regards,
Attachment: MV69x.jpg
(Size: 965.91KB, Downloaded 1217 time(s))
Oliver Archut
www.tab-funkenwerk.com
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| Re: Gefell UM70/MV692 combo -- fact or fiction? [message #435530 is a reply to message #435185 ] |
Mon, 20 July 2009 12:45 |
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Oliver Archut
Messages: 1165
Registered: April 2004 |
Platinum Member |
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Attachment: MV69x1.jpg
(Size: 462.88KB, Downloaded 1193 time(s))
Oliver Archut
www.tab-funkenwerk.com
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| Re: Gefell UM70/MV692 combo -- fact or fiction? [message #440778 is a reply to message #436007 ] |
Wed, 19 August 2009 18:01 |
volki
Messages: 272
Registered: June 2004
Location: Berlin, Germany |
Active Member |
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just bumped into this thread. some small additions:
the "handle" of the mike, meaning the metal tube housing the electronics, may also be called "impedance converter", so it won't get confused with a micpre. that's actually the labelling gefell use themselves (if i'm not totally mistaken). schoeps, as a counter-example, simply call it "amplifier", others call it "head amp" or "capsule amp". it is indeed an amplifier circuit, but what it does primarily is convert the capsule's high capacitive impedance to a low (and mostly ohmic) one, so it can be interfaced via cables of more than a few inches length in the first place 
as for the IC in the MV692, it's actually not an op-amp, but merely the MV691's o/p transistor and associated resistors in one package. so i would still count it as discrete...
i've seen an MV690 schematic containing a germanium output transistor. interesting detail, though i don't think it would sound very different - probably just the noise floor is higher
IIRC, MV690 doesn't have the second ring-shaped gap at the head piece (for the second polarization voltage), so the UM70 is likely not to fit for mechanical reasons alone.
regards
Volker Meitz
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| Re: Gefell UM70/MV692 combo -- fact or fiction? [message #440835 is a reply to message #440807 ] |
Thu, 20 August 2009 05:55 |
volki
Messages: 272
Registered: June 2004
Location: Berlin, Germany |
Active Member |
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@ oliver:
do you happen to know the contents of that metal can in the MV690? i first thought that it might contain the DC/DC converter, but since MV690 obviously does NOT contain one... ?
Volker Meitz
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| Re: Gefell UM70/MV692 combo -- fact or fiction? [message #454216 is a reply to message #454158 ] |
Thu, 12 November 2009 10:29 |
Haolemon
Messages: 91
Registered: April 2004
Location: San Francisco |
Member |
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Since I got a prompt answer from MG, I thought I would share the information. Given the circumstances, I don't think Herr Militzer will object to my quoting him:
"Dear Gary,
Thanks for your inquiry and for using Gefell Mic's.
The "S" stands for 80V charging voltage for the M7 capsule.
Before the "S" versions, the microphone had only 60V for the M7.
The 80V make the mic more sensitive.
If you need further details please feel free to contact me again.
Michael Militzer
Sales Engineer"
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