| David Royer MXL 2001 tube mod [message #151081] |
Tue, 25 April 2006 14:11  |
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 Vertigo
Messages: 1334
Registered: April 2004
Location: Atlanta |
Platinum Member |
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I got a couple of MXL 2001's for free when I bought a pair of MXL 603's a couple of years ago. The 603's were "ok" on a couple of sources, but I found the 2001's to be completely worthless so they sat in a drawer in my workshop for about two years. Then I came across this Tape-Op article by David Royer about rebuilding the MXL 2001 microphone and thought I'd give it a try:
http://www.prosoundweb.com/recording/tapeop/tube_mic_25_1.sh tml
I've since completed the project and finally got a chance to give the mic a good test drive, so I thought I'd post about it. I know the MXL is a budget mic, but due to the technical level and DIY spirit of this project I thought it might belong here in the "Whatever Works" category. Terry or Ross - please feel free to move this over to Harvey's if you feel it doesn't fit.
The idea of this project is to scrap the electronics in the 2001, and replace them with a 5840 tube based head amplifier powered by an external PSU. Mojave Audio no longer sells the kits for this mod, but Dusty Wakeman was able to find a couple of printed circuit boards for the head amplifier and power supply that they had lying around the shop. I'm not certain that they're still selling the PCB's, but the circuits are fairly simple so a printed circuit board really isn't necessary. It just saves you time and the risk of wiring errors. Just be sure you know how to read a tube schematic.
I started by disassembling the mic and stuffing the components into the new PCB's:
And here is a not-so-clear pic of the "gold sputtered mylar capsule". These capsules are showing up in a lot of Chinese mic's these days - they're a copy of the U67 capsule:
I picked up an M-160 ammo case from the local Army Surplus store for about $5. Here it is before drilling and painting:
Drilling it out was easy enough, but I didn't have a bit large enough for the panel-mount XLR jacks. So I used the largest metal bit I had (3/4") and then used a Dremel with a grinder attachment to grind out the holes until they were the proper size. It was a bit of a pain to do, but it was fun to see the sparks flying all over the workshop. I used a file to add notches in these holes to match the notches on the panel mounts, which worked out to a perfect fit.
Here is the ammo case after drilling and painting:
I then mounted the PCB and all of the switches, and wired everything in. Here is the PSU after stuffing and wiring:
And here it is completed and powered on:
Here is the completed mic (tube side):
And again (component side):
Once all wiring and assembly were complete, I tried the mic out for the first time - and was immediately bummed! Very little output, and a LOT of distortion. Something was definitely wrong... I spent a few hours tracing circuits and measuring voltages and was unable to find any errors, so I contacted Dusty again and he put me in touch with Dave Royer. Dave walked me through some measurements over the phone, after which we discovered that the transformer was open-circuited (meaning that the internal windings were broken or shorted). He had some interesting (and humorous) theories about why this sometimes happens - including the chemical composition of women's sweat when they're winding transformers during their menstrual cycle.
I actually had a humorous theory of my own as to what was wrong with the transformer, but I chose to keep it to myself to avoid my own utter embarassment. Those of you that keep up with Klett's forum (now Hecht's) will know exactly what I did wrong (sigh)...
So a few days after a call to Jensen, a new transformer arrived. I ran right downstairs to the workshop and spent a few minutes wiring it in. I then plugged the mic into my PA, powered it on, and gave the tube a few minutes to warm up. I gave it a quick "check 1 2 3" and... It bellowed right at me! Awesome!
I tried it out on my own voice and found it really smooth, with a very rich and rounded bottom end. There was a definite peak at around 6k (which I was expecting), but the high end remained smooth and unharsh. And driven hard, the mic has a VERY pleasant soft clipping characteristic, which doesn't get too muddy. Given the frequency response, my initial thought was that, aside from vocals, this would be a great mic to try out on toms.
I got to put it through its paces on a project I tracked last week. I placed it on the drummer's floor tom, about 4" away, aimed at the center of the drum (as per my usual). And it was absolutely the best floor tom sound I've ever gotten! All of the effort and expense the build the mic was worth it for this purpose alone. It was even a nice compliment to the sound of the D19's I used on the rack toms.
After the instruments were tracked I wanted to give it a try on the vocalist. This was a death-metal screamer, so I had an idea that the soft clipping characteristics would probably be a good match. So I standed the mic next to one of my modded MK-012's with an M3 Lomo head and had him take a pass on each.
Now here is where the differences in capsule quality became apparent. The Lomo is a Russian-made replacement capsule for the U87, and it's not quite a Neumann, but it's a great capsule in its own right. The Chinese made MXL capsule is a "good" capsule, but not great.
The tube-modded MXL had more meat and "girth", and the overdriven sound was VERY complimentary to the music and the vocalist's style. But the Lomo was definitely bigger, and more "in your face" sounding. The Lomo on its own was a bit too clean for this vocalist, and not as meaty as the MXL, but the two of them together... WOW! I had him double all of his vocals with both mic's and the blend of the the two of them was just perfect.
So it's working out quite well for me, and the project itself was a great learning experience. The only shortcomings of the mic are in the capsule - it's no U67... But in my opinion a "good" capsule + "great" circuitry can still equate to a great and useful mic. This was an excellent addition to my mic locker, and well worth the effort. In fact I'm actually considering building another one in order to have a stereo pair...
Total cost: <> $200 (with $75 of that being the transformer)
Total time: <> two weekends
I'll update this as I get the chance to try the mic on more sources. I'm thinking acoustic guitar might be the next thing to check out.
-Lance
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| Re: David Royer MXL 2001 tube mod [message #151381 is a reply to message #151081 ] |
Wed, 26 April 2006 11:09  |
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Rockin' Lance! Thanks!
M
All that is neccessary for bad music to succeed is that good ears do nothing, and blow up the internet with contrived viral marketing.
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| Re: David Royer MXL 2001 tube mod [message #152430 is a reply to message #151081 ] |
Sun, 30 April 2006 18:32 |
John Jennings
Messages: 2
Registered: October 2005
Location: Burbank |
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Nice job Lance! Looks like a clean mod. I hope you get a lot of good use out of that mic.
Mojave stopped making the mod kits last year. We'll always support the mics that people built from kits they purchased from us, but Mojave is definitely out of the kit business now. Sorry to say that there aren't any circuit boards left either. We get a lot of requests for them, but they're all gone.
The capsules in Mojave Audio's large diaphragm mics are similar to those in the Marshall mics, but they don't come from the same factory, the build quality is better, and they sound a bit smoother. I think that modded Marshalls sound very good (especially for the money - pretty much unbeatable), but Mojave's MA-200 is a step up. You'll hear it if you put the two mics side by side.
John Jennings
Royer Labs
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