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Filters/Equalizers / Re: EQP1A Standard Test Procedure
« Last post by dbonin on January 21, 2021, 10:04:25 PM »
Thanks Ian, Doug.
Brewery / Re: Raspberry Pi does it again
« Last post by Gold on January 21, 2021, 09:47:34 PM »
We also hired someone from Hopkins last year who stuck one in a rocket hooked up to a radio transmitting flight data as a cheap black box.

From APL? My uncle spent his career there.
Microphones / Re: Official C12 Clone - Build and Support Thread
« Last post by Haberdasher on January 21, 2021, 09:40:36 PM »
I somehow neglected to order 30M resistors (I used 100M for R15, 16).  Looks like mouser is out of stock.  I do have metal film 33M here for R11 Vishay VR37000003305JA100.  Is that going to be ok?

Brewery / Re: Raspberry Pi does it again
« Last post by midwayfair on January 21, 2021, 08:59:58 PM »
Nice price. They've come down quite a bit. A few of the people in my OS class used them for their term projects, one of which controlled a drone. We also hired someone from Hopkins last year who stuck one in a rocket hooked up to a radio transmitting flight data as a cheap black box.

When I was a kid, we actually did learn some programming in elementary school, but it went away a few years later (the closest thing when I was in high school was a basic computer literacy course -- typing, office suite, etc.), and when I was working as a sub after my first degree, it wasn't being taught at any grade even in the magnet public schools. It's starting to come back as the school system discovers that some familiarity it is a basic modern life skill. Hell, the BASIC my dad taught me when I was 6 paid off when I was working as a science editor in my 20s. I can't fathom why it didn't just stay part of the curriculum.
Brewery / Irish Stockbroker firm predicts 4.8% growth in 2021
« Last post by Tubetec on January 21, 2021, 08:38:45 PM »
despite the damage caused by Covid to highstreet trade ,small/medium enterprise and the hospitality sector in Ireland, one of the top firms of stockbrokers predicts an overall 4.8% rise in economic output in 2021. 2020 saw a rise of around a 2.5% . Of course the fact that the rise is due to Big Pharma/Chemical and IT alone hides the true scale of the damage to indigenous business , not to mention we pay more for our prescription dope here than almost everywhere else in the EU, but I guess thats the thanks you get for allowing your people to be used as guinea pigs  >:(
Dynamic Processors / Re: GSSL HELP THREAD!!!
« Last post by living sounds on January 21, 2021, 08:29:18 PM »
Thanks for the detailed explanation.
I did everything here. All Pin 1 connected to chassis. Bolted with the earth from mains inlet. CRC board ground is now connected to Chassis at the bolt. I Check the voltages and find out that 7815 was not working properly so I replaced it. But, The hum is still there. Is there any schematic or a link to a schematic for the proper CRC board for GSSL? Is it also connected to main at some point? Inpult voltages on CRC board are 22V ac and output are +27.1V and -27.8V DC. Is this normal or am I missing something here?

Something is probably wrong at the input of the CRC board.

I can't see what kind of transformer you are using. For +/- 15VDC a center tapped dual 15V trafo will be fine. A dual 22V trafo would be excessive and force the regulators to produce a lot of heat. With the CRC board an 18V trafo might be best, since there needs to be sufficient voltage for the regulator to drop some.

You need a transformer with two identical secondary windings. If you don't have a drawing for the trafo, connect one wire from one secondary to one wire of the other secondary. Measure the voltage across the other two ends of the secondaries. If you measure a very low voltage and you connect those ends to each other, the windings will be in parallel, but if you measure about 30 volts, the wires you've already connected will be the center tap of a 15 - 0 - 15 secondary.

Take a look at the image. The blue connection between 4 and 5 is your ground and goes to the ground connection of the input side of the CRC board. The other two wires (3 and 6) go to the other two inputs of the CRC board.
Drawing Board / Re: What's up with OEP?
« Last post by CurtZHP on January 21, 2021, 08:27:41 PM »
Ordered some of the cans from Farnell UK before Xmas and they came without the plate. Spoke to Farnell who said they werent sure if the plate was being supplied anymore.
So contacted OEP who were very apologetic and said yes, the plate should have been supplied and sent me some direct.

So the ones Newark got from OEP were probably from the same batch that Farnell UK got.

That's good to know.  How did you contact OEP?
Brewery / Re: Raspberry Pi does it again
« Last post by pucho812 on January 21, 2021, 08:09:43 PM »
There is a guy on GitHub who is making a working uptown automation system with a raspberry pi and uptown faders.
Hey Everyone. I ran into a problem (that i think i solved) but wanted to put it up on the forum incase it helps any one in the future.

I made a vp28 about 8 months ago and LOVE it. Use it for everything. So what comes next? Another one of course!

I bought it (watched the website like a hawk as it sold out in less than 3 days), and got it built. Upon trying it out for the first time it sounded like the 160hz was stuck on. My first move was to try the DOA’s (all 4 are self built 0252’s) from my first successful build in the new module... no good.

Then I tried my new DOA’s in the old module and got vastly smaller signal than it should with or without the 160hz drop. I thought strange but... ah- ha?

So i put the old DOA’s back on the old module and back in the capi 511 rack. There want really any reason to, but i tried it out anyways. Low and behold my previously working vp28 and DOAs had super low signal. I wasnt stoked.

I started with troubleshooting my new build. I could go on in detail about what i tried (rack spots, cables, reflowing, resistor checks, voodoo), but in the end I found that my output transformers blue and green cables didnt have any continuity when all the others did. I find it weird that that would just cause the low end to drop out, but im just a stubborn dude with a soldering iron.

The first module wasnt working because one of the feet for the opamps lost their connection to the PCB when i swapped the DOA’s. they all felt solid, but when i reflowed the solder it worked again.

I just ordered another transformer (and an extender kit) about half an hour ago, but ill let you know if it doesnt work.

I read all 54 pages of this thread and although read ALOT of useful info, thought this little anecdote might help someone down the line.

Thanks for designing such killer stuff guys. Cant wait to have my 2nd vp28 up and running!
Machine Shop / Re: API knobs
« Last post by john12ax7 on January 21, 2021, 07:56:13 PM »
The 6mm 1/4" thing has been an ongoing annoyance for a long time.  I think the API knobs are usually 1/8" or 1/4".

Vemaline seems to be the original manufacturer so you could look for them as well.  Don audio has some API style knobs for sale,, but in a common tale of knob annoyance they don't specify the diameter.
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