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Black Market / looking for some parts for Neumann KM84
« Last post by andre tchmil on Today at 06:13:07 PM »
Hi , I'm looking for the plastic slider part that switches the -10 dB pad on a KM84 microphone.
And the purple mica tube holding the slider on the body part.
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Drawing Board / Re: Marshall JTM45 clone with 30W of power.
« Last post by john12ax7 on Today at 05:46:11 PM »
Cathode bias would work,  but it's a more noticeable change in tone and feel of the amp when going from fixed to cathode bias.  So it really depends on the sound you are going for.
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The Lab / Re: Noise in tube mic pre gets worse when chassis is closed
« Last post by rock soderstrom on Today at 05:42:31 PM »
Quote from: hop.sing on Today at 04:34:43 PM
:-)
A bit over my head, what might be a possible remedy, more and better shielding inside the chassis? Transformer orientation? (I already tried that with little success)
Building a new backlid from a different material, probably possible but would be ugly, the case as is is so beautiful.

Yes, the metal lid "shorts" the magnetic field of the power transformer. Aluminum would be better than steel.  I had the same issue with a 1HU 19" case made of steel.

Something like this could be a solution.

https://www.don-audio.com/trafo-shield_3
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Drawing Board / Re: DB25 V2
« Last post by NOON on Today at 05:41:52 PM »
I designed a DB25 board purely for input/output purposes, no summing system. It has the 3 pin Molex style connectors for easy connection to shielded cables and caps to chassis ground for RF. Feel free to pinch ideas from it if you think they're relevant. (top GD plane turned off for clarity)
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Black Market / For sale [EU] Revox M3500 microphone
« Last post by tazwolf on Today at 05:38:12 PM »
HI
Revox M3500 microphone  with tuschel to xlr cable.
Silver, good condition.
100Euro + shipping.
Location Sweden.
/taz
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Black Market / Re: FS: 2 x Lundahl LL1524 = 55euro
« Last post by andre tchmil on Today at 05:00:38 PM »
1 pair available
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Black Market / Re: FS- DBX 202c goldcan VCA - SOLD
« Last post by andre tchmil on Today at 04:59:13 PM »
sorry to hijack this thread.  I think I have a goldcan available
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The Chamber / Re: REW Update
« Last post by trobbins on Today at 04:57:41 PM »
Yes it is "horses for courses".  For valve amps, it can show parasitic feedback resonances coming out of the noise floor well before they would ever show up in a waveform.  And with 96kHz bandwidth, i reckon i would see anything amiss from an 807 acting as a radio tx, as something would fold back in to tha audio band.

But i get the scope out for X-Y low frequency phase shift and resonance effects - it can be fun trying to use various tools to gain a better awareness of some topic.
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The Lab / Orban 111B No Output Either Channel
« Last post by sws2h on Today at 04:43:23 PM »
Last week I bought a broken Orban 111B. For some reason a previous owner removed the dual input/output attenuation potentiometers 😳. They aren’t jumpered so obviously it doesn’t pass signal.
They are an unusual pot because it has two values...10K and 500K log clockwise.There isn't a readily available modern alternative so I ordered individual pots from Mouser.

Unfortunately I'm not getting any reverberated output. One the left channel, using the "mixed" output I get dry, unaffected signal and the input does turn it up or down, but the output doesn't do anything. If I increase the input, the "limiter" indicator flashes so I believe it's getting that far! Using the balanced, all wet output I get nothing.

On the right channel, again using the "mixed" output I get dry, unaffected signal but it cuts out. However the "limiter" indicator stay solid no matter what so not sure what's going on there. Using the balanced again nothing.

Any thoughts on where to start? I recapped the electrolytic caps.

Here's the schematics: http://www225.pair.com/audio/waltzingbear/Schematics/Orban/111B.htm
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Microphones / Re: Neumann Vintage U87 Clone : Build Thread.
« Last post by PG_Sax on Today at 04:42:27 PM »
Quote from: Haoxian on November 17, 2018, 03:22:13 AM
How did you solve the problem? My FET will not work for 5 minutes after starting up because the voltage is too low, but will slowly rise to 9V after 5 minutes and maintain a perfect sine wave. It makes me sad

For me the was a electrolytic capacitor that was orientated the wrong way. Think it was C8.
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