D-EF47 Tribute To Oliver Archut U47 Build Thread.

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Bonnie1

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Since I'm using a 'stock' AMI power supply, I haven't messed with the heater voltage at all--I tried building my own power supply based on the schematic, but I was in over my head once I got to the wiring stage.

Interesting! Hadn't heard of anyone using a PF86 in this circuit. I wonder if it's worth trying in my mic, considering I don't have the capability to adjust the PSU.
Your PSU from AMI has 2x internal trimmers, Fil. 0-8vdc / B+ 116 - 120vdc
 

TLRT

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Guys I'm still selling many Telefunken/Siemens EF800/EF802, you can find me in the Black market section
 

Purplenoise

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Guys I'm still selling many Telefunken/Siemens EF800/EF802, you can find me in the Black market section
I’ve gotten a few ef800/802s from TLRT. Great prices and perfect condition. Like new and no noise or microphonics. Highly recommended
 

ElSmurf

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I have a question I can’t seem to find a clear answer to - does it matter if the laminations of the transformer connect to ground? I’m using Moby’s BV08 and it seems inevitable there will be a connection to ground, either through the mounting screws or the inside of the mic body.
 

Purplenoise

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I have a question I can’t seem to find a clear answer to - does it matter if the laminations of the transformer connect to ground? I’m using Moby’s BV08 and it seems inevitable there will be a connection to ground, either through the mounting screws or the inside of the mic body.
Use plastic spacers before the nut
 

Bonnie1

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I have a question I can’t seem to find a clear answer to - does it matter if the laminations of the transformer connect to ground? I’m using Moby’s BV08 and it seems inevitable there will be a connection to ground, either through the mounting screws or the inside of the mic body.
Transformer lam's should indeed connect to mic chassis.
 

Purplenoise

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Transformer lam's should indeed connect to mic chassis.
Early 47s had a shield I believe connected to ground. The later versions I guess ground the lams by the mounting disk. There is no harm but is it necessary? I have made a d-ef47 and a point to point following original schematics and there are absolutely no issues ( that I know of :) with lams not touching the chassis.
 

innercityman

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I have a question I can’t seem to find a clear answer to - does it matter if the laminations of the transformer connect to ground? I’m using Moby’s BV08 and it seems inevitable there will be a connection to ground, either through the mounting screws or the inside of the mic body.

I was wondering the same, and I decided to use Colson strips instead of nuts and bolds. It's tight and solid enough to me so I'll let it like this.
 

Purplenoise

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After finishing a ptp 47 clone my quest for a 47 is over. Now I am thinking of changing my D-EF47 towards something more modern…a modern 47. Thinking of using a toroidal output transformer, heiserman hk-47 and modern components for a cleaner sound.
Has anyone tried something like this? Impressions? Tips?
 

Purplenoise

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So I started the experiment of a “clean” 47 and it’s very promising.
Metal film resistors, pp cap for c3, v-cap oimp for c2, terrapin 7.5:1 toroidal output transformer…all modern components.
The capsule now is Danys D7 but I’ll change it to a heiserman eventually for a little more high end and less vintage vibe.
The tube is a tfk ef800 and the circuit stock d-ef47. So far it sounds really smooth and balanced with great reach. Not as aggressive and forward in the midrange but still pretty big and bold.
 

dasnevestheo

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Hey there,
So here I am with my weird PTP 47, still sounding amazing but randomly bursting some weird noises : I had the chance to recording just the noise for demonstration :
Does this sound familiar ?
At first I thought this could be humidity related but my studio is a solid 50% humidity..

Tube is siemens EF800, capsule Beesneez K7, caps NOS russian PIO
 

alphasnk

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Maybe try to see if you don't have something creating a short inside? Does your PSU for the mic have a led, does it blink along with the noise?
 

Purplenoise

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Hey there,
So here I am with my weird PTP 47, still sounding amazing but randomly bursting some weird noises : I had the chance to recording just the noise for demonstration :
Does this sound familiar ?
At first I thought this could be humidity related but my studio is a solid 50% humidity..

Tube is siemens EF800, capsule Beesneez K7, caps NOS russian PIO
Start with the easy stuff first before major troubleshooting. Clean the pins of the tube you have. If problem persists change tube. Once you have eliminated the tube then inspect the cable paying very close attention to the xlr connections/soldering.
 

wave

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Start with the easy stuff first before major troubleshooting. Clean the pins of the tube you have. If problem persists change tube. Once you have eliminated the tube then inspect the cable paying very close attention to the xlr connections/soldering.
Hi Purple,
That's the capsule causing that noise

-Dave
 

Purplenoise

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Hi Purple,
That's the capsule causing that noise

-Dave
That’s what I am afraid so too but I think it’s good to take the easy stuff out of the equation first just in case. I have had a similar issue, but without the extreme spikes, and a simple resoldering of the capsule wires fixed it. But then again I have had dirty pin tube contacts causing random crackle noises and a little bit of cleaning fixed it. Ughhh…I hate troubleshooting hahaha
 

dasnevestheo

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I'm also suspecting the capsule now, it makes sense since I also had similar effect when using it as a drum overhead, it would make crazy spikes when the bass drum would hit. I suspected microphonic tube but maybe the capsule membrane is damaged and it's touching the backplate ? Could explain the spikes maybe...
So I grounded the tube grid to isolate the capsule. microphone has been on for almost an hour and no noise, just standard tube noise. Hard to say if the issue's gone because the spikes are really random...
Let's wait and see I guess !
 

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