07 September 2014

6AK5 mic finished!

-Smoke test sat

-Optest sat, although I may have wired the omni/card switch the other direction. Will need to actually use next to see how it sounds,just did a quick check out

27 August 2014

6AK5 mic almost finished.

All the soldering is done, now just putting it back together. Took some pictures, but a little embarrassed; some of the worst soldering I've ever done...

21 August 2014

6AK5 update

Changed my mind about upping the B+ don't see where that is worth the trouble. Also, the кондензатор turned out to be too big, so in goes a smaller 2.2/250v.

19 August 2014

6AK5 microphone update

MXL V89MBP donor body for RoyerMod/BigUgly/G7'sh mic update 19 Aug   

I'm not a professional blogger. So if anyone has suggestions as to how to best organize this, please feel free to educate me....

13 August 2014

Check out this site for similar schemos (6AK5 project)


 The Sela 12 uses a 60v B+, so no voltage divider for the capsule. Pretty simple circuit. I am thinking about bumping up my B+ a bit higher on this one though. The 6AK5 looks like it can take a bit more than the 5840. I'm not sure that would make that much difference though. I also have an MXL 9000 that I've been looking at. There was a discussion on that mic at GroupDIY. Although looking at it, I had a bright idea to put in an EF86 maybe and swap a few parts. The tube is wired in parallel so comparing the pinouts for a 12A*7 and the EF86, it's only a matter of swapping a couple of wires for the tube. Then look at the G7 vs the MXL9000?

29 July 2014

21 July 2014

MXL V89MBP donor body SELA/Royer/G7sh

MXL V89MBP donor body for RoyerMod/BigUgly/G7'sh mic update 21-July

Picked up one of these that was not working on battery. Had the hole already cut and a switch so thought to make cardioid/omni version of the Schoeps circuit. (I am not interested in doing any metal work)  Upon a brief inspection, some of the circuitry is on the main board on a smd circuit board, and some on the board containing the switch. Seemed too complicated now.

But there is about the same amount of space as found in the MXL 9000/76t; so I thought I could just gut the thing and do a point to point SELA/Royer'sh with a 6AK5 instead of a 5840 and a dual sided capsule. I have some generic K47 clones so will use that. Will post some pics of the internals soon. One more project on the table. This should be relatively simple though.

Have taken apart mic partially, removed XLR plug (which was in pretty tight) remembered this time that the screw is threaded counter-clockwise and tight is up not down. The switchcraft I have will go in much easier. Need to solder the wires to it next. I've sketched out a schematic and a parts placement guide. Plan to leave the switch board in place as it already is lined up, and just remove all the other parts on it. Here is my schematic, the circuit is pretty much the Royer/SELA with an added grid resistor (I have a 2G to try out, with longer leads than the 1G's from the original mic) also an omni/card pattern switch. I want to keep my PSU's consistent (for no good reason, I'm not going to have that many....) so will use the  100/60 voltage divider as in the Royer rather than the  120/60.

 Here is my proposed layout, basically following the schematic:

The transformers are noname appr 11.5:1 or so. I used one in my other RoyerMod 2001, and in the "U87 Front End" mod I did to another 2001. I got several of these off Ebay and in a trade.

20 February 2014

Tube compressor with 6AL5 sidechain and remote-cutoff pentode.

Started a discussion at GroupDIY and DIYAudio. Saw a circuit fragment in an ARRL handbook from 1961. While I am not a designer at all, (and still find it a difficult mental exercise to calc a plate curve...) this looked intriguing.The circuit fragment uses a 6AL5 in the side chain. The circuit calls for a pentode input stage and uses the suppressor grid on the pentode; I've seen other circuits that do this with 6BA6, and decided to give it a swag.

updated  26 Feb 21:00 HST

12 February 2014

In fact, i'm not on Facebook at all... Under any name. Probably need to do that at some point.
OK, I post on a handful of audio related forums as Blue Jinn. There are other Blue Jinn's out there (and here I thought I was so damn clever.) I post on: homerecording.com groupdiy.com tapeheads.net tapeop.com diyaudio.com gearslutz.com Elsewhere I may be known as Waterproof Blue. In fact I started out with that, and switched to Blue Jinn when I couldn't properly set up the Waterproof Blue name on one of them .I'm also blue_jinn on Ebay.