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Microphones / Re: Is Aurycle still in business?
« Last post by Spencerleehorton on Today at 09:05:11 PM »
As soon as they turn up I'll let you know
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Mixers/Monitoring Systems / Re: Tube Mixer
« Last post by Whoops on Today at 08:43:55 PM »
What design are they?

Ian's own tube designs
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Just substitute a 7.5 or 8.2V Zener for the 1K resistor in your original drawing which places the Zener in series with the coil.

Zener cathode points to the coil. Zener anode to -16V.
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Black Market / FS: 2 API 312 PCB’s
« Last post by fsalter on Today at 08:14:12 PM »
For sale are 2 API 312 preamp pcb’s with their switch pcb’s, designed by Eric Labrie of Quebec. I had 4 and decided to build only 2 (and regretted it). They are super easy to build and sound great with the right ingredients. I have all the docs.  50$ for both.
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Drawing Board / Re: How could this work? (+/-24v w/ 48v)
« Last post by squarewave on Today at 08:12:11 PM »
So, re-racking a pair of clrec modules that were seemingly well done but quite ugly. The external power supply is a bipolar 24vdc power one. Somehow the previous setup was getting phantom out of it as well. I would assume they were using the -24v as the phantom common.

How can this work though if pin 1 is tied to the chassis and  the +/-24v common? Would I have to float pin 1 from the chassis?
Pin 1 MUST be connected to the chassis. Instead, you use a virtual ground. Like in guitar pedals. Preferably it should be active using an op amp to drive the ground (as opposed to a giant capacitor between the virtual ground and -24 which is earth ground. But you can't really source / sink a lot of current from / to the virtual ground. You can only use it to bias things. Or at least you should only use it to bias things. So if there are outputs of amps driving into ground or LEDs or relays dumping current into ground, it's not a good idea. And you need caps on outputs if they're not transformer outs. If you have a pointer to a schem I can tell you if it will work well or not.

The virtual ground trick works perfectly fine if you're just biasing an op amp input or sourcing and sinking equal currents through at least 10K or so. But otherwise, for a pro-build, I personally would just get two appropriately sized 24V SMPS and the smallest 48V SMPS you can find. Then stack the 24V so that the intersection of the two is your ground (which you can now connect the chassis and pin 1). Or maybe get another very small 24V and stack that on top of the upper 24V. Both 24 and 48 are common voltages for stock SMPS. I like the MeanWell supplies but they get some hate around here for being LED supplies. For some reason people don't realize that they're all LED supplies. I have no clue why it would many any difference. 200mV ripple at 50kHz is easy going with a small choke and an even smaller cap. That can make a really nice clean, sturdy supply with no mains hum.
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Drawing Board / How could this work? (+/-24v w/ 48v)
« Last post by RSRecords on Today at 06:14:13 PM »
So, re-racking a pair of clrec modules that were seemingly well done but quite ugly. The external power supply is a bipolar 24vdc power one. Somehow the previous setup was getting phantom out of it as well. I would assume they were using the -24v as the phantom common.

How can this work though if pin 1 is tied to the chassis and  the +/-24v common? Would I have to float pin 1 from the chassis?
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Brewery / Re: Ultimate Food Hacks Compilation
« Last post by cyrano on Today at 06:13:51 PM »
I made it up to the potato. And, no, you can't make fries like that.  ::)

There are no real hacks on Youtube.  ;)

Although this is still a million times better than "Five minute crafts" and their hundreds of support channels.
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The Lab / Re: Anyone know about this old neve microphone mixer
« Last post by cyrano on Today at 06:09:55 PM »
@Ian

I wasn't dishing passive mixers, Ian. The "ouch!" was because I kinda like the thing. And Pucho confirms my fears, as it's being cannibalised.

If the owner is only interested in the transformers, maybe Pucho could inherit the rest. It would still look fine from the front  ;)
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Brewery / Re: covid politics
« Last post by cyrano on Today at 05:35:29 PM »
“Follow the Money: How the Online Advertising Ecosystem Funds COVID-19 Junk News and Disinformation.”

https://comprop.oii.ox.ac.uk/research/covid19-disinfo-seo/

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The Lab / Re: Plate Reverb pre EQ Issue
« Last post by deveng on Today at 04:32:01 PM »
In the early stages of my plate I had built a pair of high impedance JFET pickup amps.   In fact it was one of the first things I built.   I just never got around to applying it to the plate since I got the Isotrons.   If I ever need to go back to it, its ready to go!   

One thing I noticed during the initial testing of the Isotrons, very quiet.   My problem with the sound appeared to be plate tension and the driver (an old Acoustic coneless driver).   It was distorting a bit on transients so drum hit attacks were not good.  Could be I was driving it too hard as that's a common issue.   I managed to get my hands on an original EMT driver magnet with the wide gap.  I purchased a 3/4" voice coil and fashioned a bullet head on it so its very much like the original EMT coil.   I need to get my plate properly tensioned first then I can drill and mount the bullet coil.    Only then will I know if I'm on the right track!

Regards,
Jeff
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