newbie builds ioaudio MK47 microphone

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Bowie

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Jun 22, 2012
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365
micaddict said:
Regarding microphonics, would these help and/or has anyone here tried them?
https://www.gcaudio.com/cgi-bin/store/showProduct.cgi?id=130
Sometimes, they can be worth trying in hopes of a small improvement but, unfortunately, they are unlikely to help much here.  They can be worth trying if you're looking to salvage some life out of an expensive tube that is microphonic.  Or, in gear/amps that are subject to vibration, like the EF86 in an Vox.  If a 6028/408a is microphonic enough to create problems in the mic then it's probably best to just move onto another tube.  The rings are unlikely to help for long. 
 

ln76d

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A friend gave me three sets of those for tests.
He was disappointed from purchase  :)
I didn't noticed any change in any type of circuit where i used it.
Waste of money, another voodoo.
If fit, can be used as gasket in water tap :p
Sometimes better result is  to use metal screen can with hard spring inside.
 

Matt Nolan

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Apr 29, 2015
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Bath, England, UK
Yeah, surely most of the microphonics in a tube come from the metal parts inside, not from the glass envelope, so damping the envelope with a rubber ring isn't going to make much difference.
 

wolcott

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Jan 1, 2015
Messages
23
strange , I've had no luck with WE tubes .
I have a bunch of jan/phillips 6028 though that are all quiet
they sound good too
 

cariocaman85

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Sep 24, 2011
Messages
54
Hello,

I've just finished my mike!  :D

Do you know where I can source good GE or RCA 408 tubes?
It seems that only WE or Philips are easy to find....

Many thanks!

Remi
 

ln76d

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Aug 11, 2012
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cariocaman85 said:
Hello,

I've just finished my mike!  :D

Do you know where I can source good GE or RCA 408 tubes?
It seems that only WE or Philips are easy to find....

Many thanks!

Remi

Are you sure that RCA manufactured these tubes?
For me RCA version looks like relabelled philips - these which i had at least.
 

Pip

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Nov 17, 2004
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626
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New York City
ln76d said:
cariocaman85 said:
Hello,

I've just finished my mike!  :D

Do you know where I can source good GE or RCA 408 tubes?
It seems that only WE or Philips are easy to find....

Many thanks!

Remi

Are you sure that RCA manufactured these tubes?
For me RCA version looks like relabelled philips - these which i had at least.

http://www.tubebooks.org/tubedata/hb-3/miscellaneous_types/408-A.PDF

Are you sure they didn't?

http://groupdiy.com/index.php?topic=47112.msg764053#msg764053
http://groupdiy.com/index.php?topic=47112.msg764111#msg764111
 

ln76d

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No, i'm not :)

These links doesn't show anything btw.
Someone subjective feelings about the tubes sound are worth not much ;D
Or do i missed something?

Like many tube manufacturers, Philips was making some tubes for RCA and RCA for Philips (and both for many others).
For example i have 20ez7 labelled Rogers by Philips and these were made by RCA :D
Usual RCA tubes had silver painted rectangular frame with model marking, except the logo.
RCA 408a didn't have it and the bulbs with internals were looking exactly the same as philips.
WE or GE looks little bit different than philips for example.

 

Avgatzeblouz

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Nov 6, 2015
Messages
159
Location
Montréal
Hi there, I'm about to take the plunge in this build, so I thought I could ask my question on this topic, hope I'm not hijacking : what do you guys recommend for a good body ? I'm looking at either Aputis or Flea, but Flea is way more expensive. Any advice ?

Thanks a lot.
 

micaddict

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Jan 3, 2012
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Welcome.  :)

If you're in a hurry; Flea.

If not, Aputis seems a good choice.

Oh, and Max himself makes one for his MK-U47.
Partly Flea, too, so you can have the pattern selector on the body.
But of course the MK-47 doesn't need that.
 

Avgatzeblouz

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Nov 6, 2015
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159
Location
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Thanks a lot. That's funny, because I emailed Max himself, and did not get any answer. I'll wait a little bit more, then, to look at his option.
 

JW

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Jun 8, 2005
Messages
893
Location
Portland USA
Finding something strange here. I wonder if this is the right thread. I believe I'm getting a polarity reversal of the transformer secondaries AT the transformer itself. As in, the way it solders to the board results in A+ being A- and A- being A+

Can somebody check that their MK47 is in correct phase, when wired like the pcb board says?

I found this when I replaced Max's MK47 transformer in one of my two MK47's with Moby's. I realized at one point that they were out of plarity with one another. I checked against two Sm58's and realized that the MK47 with Moby transformer matched the polarity of the Sm58's and the one with the original MK47 transformer needs to have polarity flipped on the preamp for them to all be the same.

So I traced and retraced the circuit after the output transformer and everything is the same on both mics from the +/- "A" outs on the mic board all the way to the XLR output in the power supply. So, I'm wondering if there is actually an error on the board, flipping transformer secondaries.

The fix is easy. Just puzzles me.

 

JW

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Jun 8, 2005
Messages
893
Location
Portland USA
Hmmmm. Okay, I flipped the phase on the output of my MK47 and now it matches the rest of my mics.
Hope people see this. You might have been recording with an out of phase mic. I can't figure out any other way that the polarity would be flipped except at the transformer secondaries. . . . .  Next time you have an MK47 up, check it against another mic for polarity. Sorry I keep using polarity and phase interchangeably.
 

mrclunk

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Nov 29, 2006
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London
JW said:
Hmmmm. Okay, I flipped the phase on the output of my MK47 and now it matches the rest of my mics.
Hope people see this. You might have been recording with an out of phase mic. I can't figure out any other way that the polarity would be flipped except at the transformer secondaries. . . . .  Next time you have an MK47 up, check it against another mic for polarity. Sorry I keep using polarity and phase interchangeably.
Think you're correct.
I had my MK47 ioaudio xform next to a real U47 and had to flip polarity on desk.
Doesn't really matter tho just changed socket wiring on PSU.
 

mhelin

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Mar 12, 2005
Messages
552
Location
Tampere, Finland
Matt Nolan said:
Yeah, surely most of the microphonics in a tube come from the metal parts inside, not from the glass envelope, so damping the envelope with a rubber ring isn't going to make much difference.
If the metal parts were magnetic an external magnet could maybe damp the ringing but guess they are not (nickel etc.).
 

innercityman

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Joined
May 12, 2016
Messages
285
Location
France
Hi everyone,

I'll start to build an MK47 bought on the black marcket and I'm actually searching for parts... Mic body, capsule, PSU case etc... I found this cheap Tube mic PSU on eBay, so I'm thinking about buying it and modify it with the Zayance's MKPSU pcb and just keeping the chassis, sockets, switch, maybe toroidal transformer if it suits. I was also wondering if it could power the MK47 with or without modifications...

Here's the link of the PSU

https://www.ebay.fr/itm/DELUXE-VINTAGE-SYLYE-TUBE-VALVE-7-PIN-MICROPHONE-POWER-SUPPLY-UNIT/352960018975?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20160908105057%26meid%3D27f5008437d24a2cb7999be087e90d8f%26pid%3D100675%26rk%3D4%26rkt%3D15%26mehot%3Dnone%26sd%3D362889269743%26itm%3D352960018975%26pmt%3D0%26noa%3D1%26pg%3D2380057&_trksid=p2380057.c100675.m4236&_trkparms=pageci%3A0aedb770-8eb4-11ea-b6fd-74dbd1802d38%7Cparentrq%3Ae43291d51710ac3dcde71cdcffba49e2%7Ciid%3A1

and here's the schematic....
 

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