Browsing all articles from April, 2008

Makin’ Mic Pre’s – The SSL9K 4 Channel Mic Preamp

Posted by DibS in DIY

Apr
28

Here’s my latest endeavor. The SSL9k 4 Channel Mic Preamp. Here’s what I’ve done so far. Power supply, Balancer, and one Mic Pre board are stuffed and ready for testing. The power supply tested at +17.99v, -18.2v and 44.8v so we are looking pretty good there. Next I have to wire up the other two cards, get the gain switch going and plug in a mic and see how it works!

One channel done and mounted.

Close up of Channel 1 and Balancing Amp

More Progress. I fired up channel one.

NO SMOKE CAME OUT!!! = AWESOME!!!
PLUGGED A MIC IN ONE END AND SOUND CAME OUT THE OTHER!!! = AWESOME!!!
IT SOUNDED LIKE CRAP!!! = NOT AWSOME!!!

So there was some troubleshooting involved. After swapping out one of the 5534′s it sounded MUCH better.

Channel 1 wired up.

Gain Switch.

Then I got started on Channel 2. This one went much faster than the first. What took way longer, though, was wiriing all the connectors and switches. Eeesh what a pain! But it’s all wired up. I plugged it back in and Channel 1 still works and Channel 2 seems to be working too. The gain seems roughly the same between both channels. +48 is also working on both channels.

Two channels all wired up.

Two Channels wired close up.

My makeshift front panel. This is temporary.

In the rack.

Logo.

UPDATE!!!
Finally finished channels 3 & 4. Had some issues with thermal shutdown on the power supply but that was fixed with a couple of these:

Couple of heat sinks and now she runs like a top.

Here’s all four channels installed.

Little spaghetti like, but I’ve seen worse.

DIY Meta

Posted by DibS in DIY

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Apr
8

LA2a Meta

http://www.prodigy-pro.com/diy/index.php?topic=3278.0
The Grand Daddy of LA2a threads.

http://www.recproaudio.com/diy_pro_audio/teletronix_la2a.htm

Awesome Cayocosta Layout and BOM

http://www.jblproservice.com/pdf/Vintage%20JBL-UREI%20Electronics/UREI-LA-2A%20manual.pdf
Manual

http://www.diyfactory.com/projects/diyla2/diyla2.htm
Another DIY LA2a

http://s11.photobucket.com/albums/a173/AnalogPackrat/Bloo%20LA2A/
Another DIY LA2a (Bloo)

http://www.prodigy-pro.com/diy/index.php?topic=21907
Explanation of where to put the grid stoppers.

RCA BA-31 Restoration Meta

http://www.waltzingbear.com/Schematics/RCA/BA-31A.htm
Schematic

http://www.prodigy-pro.com/diy/index.php?topic=28210.msg341628#msg341628
Great analysis of the schematic by PRR

http://www.prodigy-pro.com/diy/index.php?topic=2867.msg180431#msg180431
Great breakdown of the RCA product line by emrr

http://www.vo-bb.com/phpBB2/viewtopic.php?p=79133&sid=b29713c1037b216131c7e2fb21b8f0bf
An example of a racked module.

http://dibsreaction.files.wordpress.com/2008/11/ba-31b_bom.pdf
My own re-cap BOM or Bill Of Materials

NYDave Mixer

http://www.twin-x.com/groupdiy/albums/userpics/balancedmixnetwork.pdf

The way I put this together was that I have it built right into my patchbay. My PT outputs normal into my mixer where 10K resistors sum the + and – sides into their respective bus wires. Odd channels sum to the left and even channels sum to the right. The last four channels of my 16 channel mixer are mono. I did this by using 14.3k in place of 10K resistors (incorporating the two resistors into one) to go to both sides.

TNC ACM Chinese Microphone Mod Meta

This is my own mic mod meta for the purposes of consolidating information on the three specific Chinese microphones I bought through the TNC Musicians Workshop “Group Buy.” When all is said and done, there will be this thread containing links and quotes from outside sources and a tread for each of the three microphones I will be addressing (I will try to credit my sources as best I can, but to all those who get snubbed, I apologize). The individual threads will cover my own personal experiences in the mic mod process. I will be updating this post throughout the process.

ACM-1200

The ACM-1200 is a rebrand of the same mic as is the Apex 450, Nady TCM1150, Avantone CV-12 and the Telefunken R-T-F M16. The mods for these mics are vast and well documented. My goals are:

Replace Tubes (Chinese 12AX7B)
Replace Transformers (Chinese Unbranded 10:1)
Remove unnecessary parts (Filter Caps to compensate crap transformer, etc)
Replace important parts (C8, etc)
Remove Cathode Follower (Unnecessary after transformer swap)
Replace multipin cable (Not first priority but definitely needs to happen)
Replace Capsule (Dale’s M7 is what I’m thinking but not ruling out Peluso’s)

Links:

http://studioforums.com/eve/forums/a/tpc/f/1526095781/m/2111089522/p/1
Main Apex thread on StudioForums.com

http://studioforums.com/eve/forums/a/tpc/f/1526095781/m/2111089522?r=4971028262#4971028262
A specific set of mods with schematic

http://www.prodigy-pro.com/diy/index.php?topic=21266
Mic Mod Meta

http://www.prodigy-pro.com/diy/index.php?topic=27793.0
ACM Specific mod thread

http://www.10000cows.com/M7CopyCapsulePhotos.htm
Dale’s Capsule Process

ACM-70

Seems to be an Apex 210 in a slightly different case. It came with a shock mount and case. I overall like the sound of these mics but some mods are going to be needed:

Change transformer
Remove inner headbasket? (Not sure about this one)
Re-Ribbon (I may send them off for that one)

Links:

http://www.hometracked.com/2007/08/17/ribbon-mic-mod-part-1-apex-205/
A ribbon mod how-to thread.

http://www.morphproductions.com/apex210transformermod.htm
Another ribbon mod how-to thread.

http://www.hometracked.com/2007/08/28/ribbon-mic-sag-and-repair/
Ribbon Sag Repair article

http://www.lkmusic.co.nz/ribbonfix.htm
Ribbon Replacement Article

ACM-3

This is an obvious rip-off of a Royer R-121 or a Bang and Olufsen ribbon mic. It sounds a bit dark and wooly as is. I’m looking forward to hearing different transformer options on this.