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Turning an old capacitive terminal keyboard from 1978 into a modern USB keyboard with fully programmable keys. Got it working fine, but had to tear it back down for keycap polishing and a few minor tweaks. Currently reapplying dielectric lube to all the key stems.


Need to finish up this project so I get back to testing Circlotron stuff.





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  • 2 weeks later...
  • 2 weeks later...

Finished up the separate "Universal" PS that will be used to power my GG. Maybe try it with a Carbon later. 


GRHV+: 404.5VDC

GRHV-: -406.4VDC

GRLV+: 15.01VDC

GRLV-: -15.00VDC

Pro Bias: settles at 580VDC

Casework by Head-Case member joehpj

Awaiting select parts on a slow boat from China to finish up the GG. 










Edited by Laowei
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Four of these - http://www.sbacoustics.com/index.php/products/subwoofers/12-sb34swnrx-s75-6/

I did plenty of research and my main goal was to find a light subwoofer driver which can do twenty. Initially I was looking at Dayton, but they're poorly represented in EU and they're anything but light. A high Mms/Bl factor was a must.

Scanspeak had a 13" which was twice as expensive. Other than that I had to look for exotics like Audio-Technology and Accuton which are even more expensive but TS specs aren't any much better.

SB Acoustics is actually a very decent manufacturer, but I'll mention that one of them came with a minor defect that's audible on higher excursion. Let's see how they'll handle it.

Edited by RudeWolf
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I know I shouldnt be posting in this thread as Im not really on this level but I saw near the beginning what I had been thinking about...... milled foam for earpads(I want to repad everything and I dont want to pay 50 bucks each or 30 plus i want to use the right foam).  I noticed the higher end K series uses gel memory foam(for bass rentention? instead of cooling(from the mattress and pillow industry)). Also, memory foam seems to be comfortable, form fitting, and doesnt pass air as easily as something like say Talalay Latex(slow recovery).  I might even do a carbon gel foam for cooling and bass retention as headphones always tend to be hot also need to do experiments with foam weight and source a good cheap quality protein leather fabric.  Just thought I would throw this out there since this is the best thread I have seen to date on this subject.  What foams did you use Kerry?  Also is that a mill built from a kit? sure looks more than good enough for making earpads..........

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  • 4 weeks later...

I went to the thrift store and there was nothing cool there until I saw this on a bottom shelf... 


They were asking 20$ with stickers that they were unsure if it worked so perfect for me.  :)  This is a PSU for Mackie mixing desks with a super long umbilical cable which I have removed.  Heavy fucker too... at least 10kg. 


Healthy output current so the idea came into my head to use it as a bench supply should it work. 


After some cleaning it looked ok with no bad caps or any visible damage.  Just look at that monster of a transformer.  So I turned it on and well it worked so this was next:


No current limiting here but hey, this one was cheap so who cares.  Also I can test large class A amps with this beast. 

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@cetoole was visiting, so we made a slightly absurd amp using parts from the bin. 


I had originally milled the chassis with the intention of building a 6E5P triode -> 4P1L triode SE; then realized that would be a bit awkward, since the 6E5P is rated for higher dissipation than the 4P1L. I may have also forgotten that 4P1L filaments need power supplies when I bought my power transformer, too, so that was a non-starter.

Not wanting to leave two unused holes in the panel, the obvious solution was to throw some 0C3s in. :) Glow tubes are pretty; it follows that any amp that uses them will sound better than one that does not. A normal person might be tempted to string them in series and use them as a reference for a regulator. Instead, each channel gets its own shunt regulator with a voltage reference made up of a zener stacked on top of the glow tube, and a SiC shunt device. R7 ensures that the tube strikes.


And the current source (which is nothing inspired)




The regulator terminates into the cathode rather than ground, keeping the cathode regulator out of the output current loop. It also forces the PNP to run at constant current regardless of cathode current, meaning its impedance will also be constant.

It sounds like a single ended triode (i.e. terrible). But it was an awfully fun build. Slightly tempted to parafeed or otherwise upgrade the iron. It's surprisingly silent when nothing is playing.

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52 minutes ago, Whitigir said:

Lol....Liquid Quantum will be the name ?

On that note... There's a rumor that Cavalli and Schiit are merging. Instead of merging product names and calling the next amp the Liquid Schiit, they're just going to call it Diarrhea.

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12 hours ago, swt61 said:

On that note... There's a rumor that Cavalli and Schiit are merging. Instead of merging product names and calling the next amp the Liquid Schiit, they're just going to call it Diarrhea.

Sad but a possible name for them.  I can't see why the two would merging.  Cavalli is highly overpriced while some Schitt(s) can be quite a good value.

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