bad mic design?

[asm]

i recently saw this pic of a mic on ebay, a u47 clone from the 70's i think. supposedly it has a real m7 cap:

http://tinypic.com/f5e6a

but ive NEVER seen the tube placed in that location, especially on a dual sided capsule.


what gives? looks to me that it would cause major problems, i thought it was always smart to have the tube sheilded and farther away from the capsule? or am i wrong?

help a curious mic-enthuasist!!

thx!
Taylor

 

[soundguy]

considering that there is a large school of people who will only hang mics with internally mounted tubes inside upside down as to disappate heat AWAY from the capsule, that just seems like the worst idea in the universe. Having a heat source that close to a capsule cant possibly be a good thing when considering a 30 or 40 year life span.

dave

 

[asm]

exctly what i was thinking about the heat issue. i just dont understand how someone could sell the mic for the 1,000$ range, and have such a crappy design like that. rest of it is laid out fine, but why they decided to stick it there just makes no sense at all.

 

[Marik]

[quote author="soundguy"] Having a heat source that close to a capsule cant possibly be a good thing when considering a 30 or 40 year life span.

dave[/quote]

In fact it would not be that much big of a problem with Mylar films, but M7 has a PVC diaphragm. Any heat source right next to it will shorten its life dramatically, as PVC tends to dry and crack.

 

[toby]

and if the tube was abit microphonic..................

i'm supprised that behringer haven't build a mic like that, just to prove it has a tube in- so you can see th e tube through the capsule, but it would have to also have a bulb in there!

 

[Marik]

Oh yeah,

Right in front of the capsule what kind of obstacle to the sound the tube is? :shock:

 

[toby]

plus it would be ace if it just fed back on itself, like some guitar amps do with microphonic tubes in.

 

[Guest]

[quote author="asm"]
http://tinypic.com/f5e6a
[/quote]
Some benefits of this arrangement:
Tube heat can dry the air, and then make capsule less noisy
In front of the capsule tube can serve as difraction element and then
improve (in positive, or negative way) high frequency response.

Be sure, that this piece have no this benefits.

xvlk

 

[zebra50]

Hi,
That capsule looks very similar to the ones in my Reissman tube mics, and the resistors look a similar vintage too. Do you have any pics of the rest of mic?

 

[asm]

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=41466&item=3758351313&rd=1&ssPageName=WDVW

 

[soundguy]

asm, your avatar is none more black. did you record it in dubly?

dave

 

[Marik]

Nickel plated M7??? :shock:
It seems that they had to put the tube next to capsule, as it has internal supply, and it might be just a matter of room restriction.

 

[Tim Campbell]

This capsule is not an M7.
This mic resembles nothing Neumann ever made.
There are some RFT mics with internal power supply.

 

[toby]

depending on his reserve it might be worth a rebuild. take out PSU and move the tube.

i only say this as it has a nice case, and i am disguistingly lazy when it comes to metalwork

 

[zebra50]

Yup, the capsule looks just like those on the small reissmann mics, except that they are gold not nickel plated. The contact to the diaphragm is made by a sprung metal bar that presses down on the skin - kind of strange as it is not screwed down or soldered. It looks like it shouldn't work but seems to be OK in the reissman mics so far. I would worry about this type of connection under high SPLs

Look out, though - zero feedback.

 

[dale116dot7]

I remember seeing some of the CMV3 capsules disassembled and I seem to recall that they used the spring contact, but I though it was a gold coating. Unless someone re-skinned it and used a straight nickel evap process or something like that (which is easier to get good adhesion to plastics). I dunno.

The spring force is likely far higher than required even at some jet engine SPL's, though there might be some resonance from the spring contact. On the other hand, a lot of SDC's use springs to make contact and they seem to work ok.

 

[Steve Jones]

I guess figure 8 isn't one of it's strong points. :wink: