D-EF47 Tribute To Oliver Archut U47 Build Thread.

[Purplenoise]

Should be easy. I cant see the power supply schematic right now but you can just leave those components out. you can leave them in too, doesn't really matter. Just don't put in the relay off current sink resistor. No real modification required. You could even use the power supply from your mic with the relay as long as the switch is off. If you flipped the switch on, there would be less current draw and your B+ would rise.

Same with the mic. Leave out the (rear diaphragm) pattern resistors and the cap that isolates the two diaphragms.

Thank you so much, I’ll look into it and maybe hit you up for clarifications if you don’t mind. Cheers.

 

[Delta Sigma]

Do you have a local copy of the schematic? Until the gdiy site file migration gets figured out, maybe post the schematic in a message so we can refer to it. PS and mic (preferably the redrawn schematic).

 

[Purplenoise]

Do you have a local copy of the schematic? Until the gdiy site file migration gets figured out, maybe post the schematic in a message so we can refer to it. PS and mic (preferably the redrawn schematic).

Unfortunately no...waiting on the site to iron out the bugs haha

 

[wrentema]

Hey First post here in this thread. Starting my build very soon. PCB Almost there.

I'm already prepping the cable and I have a question about the wiring. I'm DIYing the cable too and using the Sommer SC-Octave Tube cable (Sommer cable Shop | Microphone Cable SC-Octave Tube; 5 x 0,14 mm²; 2 x 0,50 mm²; PVC Ø 6,50 mm; grey | purchase online).

Two of the wires are thicker (Green/Blue). So my question is: Do I use the thicker wires for H+ and B+. Or is it for H+ and ground?

I'm assuming Orange/White should be A+ and A- since they're twisted together (correct me if I'm wrong).

Thanks

 

[egroys]

H+ and Ground should be the two thicker wires. Otherwise, the colors do not matter as long as you maintain consistency

 

[dmp]

This is how I would do it:
Yes, twisted together should be audio
Blue/Green should be H+ and H-(gnd)
Red B+ and Black B-(Ground)
Purple can be pattern.
Keeping the heater ground and B+ ground separate in the cable gives you options to minimize ground noise.

 

[Purplenoise]

I always thought that the thicker wires should be for H+ and B+

 

[dmp]

You need thicker wire for higher current. The current to and from the heaters is high, the B+ current is very low.

 

[dasnevestheo]

Should be easy. I cant see the power supply schematic right now but you can just leave those components out. you can leave them in too, doesn't really matter. Just don't put in the relay off current sink resistor. No real modification required. You could even use the power supply from your mic with the relay as long as the switch is off. If you flipped the switch on, there would be less current draw and your B+ would rise.

Same with the mic. Leave out the (rear diaphragm) pattern resistors and the cap that isolates the two diaphragms.

Hey ! I'm having a relay-less mic in cardoid only and leaved the relay resistors is the PSU, shorting the COM and CRD pads. I indeed have a rising B+ problem causing audio dropouts after a few hours (at least I think that's the culprit). Do you recomend just removing R9 and R5 as well as leaving the switch pads alone, and not connecting pin 6 on the XLR ?

 

[wstratton]

My sole EF800 went microphonic, so today I popped an old Mullard EF-80 in and it sounds rather nice, if a bit less refined. I ordered a couple EF802s and an EF184--looking forward to trying them all out in conjunction with the Thiersch Blueline capsule.

 

[dasnevestheo]

My sole EF800 went microphonic, so today I popped an old Mullard EF-80 in and it sounds rather nice, if a bit less refined. I ordered a couple EF802s and an EF184--looking forward to trying them all out in conjunction with the Thiersch Blueline capsule.

What were the symptoms of the EF800 going microphonic ? I'm not sure if mine is...

 

[wstratton]

What were the symptoms of the EF800 going microphonic ? I'm not sure if mine is...

It developed some relatively high self-noise, as well as a faint ringing sound on sibilants. Not enough to render the mic useless, but enough to be annoying.

 

[dasnevestheo]

Cool, that's good to know. Please let us know how the other tubes compare !

 

[wstratton]

Cool, that's good to know. Please let us know how the other tubes compare !

Will do!

 

[Delta Sigma]

Hey ! I'm having a relay-less mic in cardoid only and leaved the relay resistors is the PSU, shorting the COM and CRD pads. I indeed have a rising B+ problem causing audio dropouts after a few hours (at least I think that's the culprit). Do you recomend just removing R9 and R5 as well as leaving the switch pads alone, and not connecting pin 6 on the XLR ?View attachment 81388

Wow. I typed a response to this but must've closed the tab before submitting it. To make things worse, I went on a two week canoe trip so I'm just realizing that I didn't submit my response now.

Don't short the CRD and COM pads. Leave out R5 and R9. Shorting CRD and COM and installing R5 and R9 will work, it would have the same effect as having the relay in the mic. The COM terminal normally switches between the relay and the R9 relay dummy load. I would leave them out though since they are unnecessary.

 

[innercityman]

Hi,

I've powered up for the first time my PSU just to check my voltages, without wiring the PCB. I put a 300mA slow blow fuse like suggested in the BOM between Live and Power trafo's brown wire and it immediately blew up. 230VAC set up transformer so Primary in series, Violet and grey together and isolated, Secondary in series with Red and orange together and isolated. So just to be sure... is the power rating (300mA) of the fuse right ? Or should I put something like a 1A fuse ?

Thanks !

 

[Delta Sigma]

Hi,

I've powered up for the first time my PSU just to check my voltages, without wiring the PCB. I put a 300mA slow blow fuse like suggested in the BOM between Live and Power trafo's brown wire and it immediately blew up. 230VAC set up transformer so Primary in series, Violet and grey together and isolated, Secondary in series with Red and orange together and isolated. So just to be sure... is the power rating (300mA) of the fuse right ? Or should I put something like a 1A fuse ?

Thanks !

Sounds like a short or incorrect wiring. Can you post pictures? Is your heater transformer wired in as well?

 

[innercityman]

Thanks for your answer. The heater trafo is wired to the IEC and on/off switch but not to the pcb yet. My light bulb blew with the fuse, I took it out and the new fuse is not blowing anymore. I measured B+ without any dummy load and I get about 100VDC. I get 23.5VAC from heater trafo which is right I guess. From the bulb socket, red wire is connected to live and white to neutral, and obviously 230V bulb.

 

[innercityman]

I forgot to mention that when polarity switch is on Omni position, B+ is rising up above 150VDC on and on and don't stop. Is that a normal behaviour ?

 

[innercityman]

Well, I inverted the bulb socket wiring and no more bulb or fuse blowing. I wired the heater transformer and measured H+ and I get a huge 27VDC... What did I miss or do wrong ???