violin
voice
Classical (nylon string) guitar
Hobbies and interests.
Large Diaphragm
The TSB-2555's finally arrived from China!
Those are the long awaited 26mm (1 inch) Cardioid Mic capsules. At $11.95 a piece, they are going to really change the DIY Large Diaphragm scene.
I ordered a couple from Mark Stong at JLI ELECTRONICS, and built away.
For this microphone, I used a slightly modified circuit. It's still the Schoeps circuit, but there's more capacitor bypassing, rolling off some high end, for a theoretically cleaner signal. Also, a couple ferrite beads and capacitors are added at the output for rfi/emi reduction, a couple diodes added as power safety and also the zener for Fet/capsule power/bias, etc. is 10 volts instead of 12 volts. Thanks to James Gillespie for these modifications.
I initially tried using 4403 transistors instead of 5087's, but was disappointed to hear a lot more noise. Maybe I picked two bad transistors. I'm going to try going through the batch I got, because I've heard these are a 'secret audio weapon' and are very quiet. What I did notice was it was really hard to find two that matched - so maybe I just got cheapos.
The circuit sounds good - very quiet, so I think I may try to make some of these changes on the other mics to see what happens.
I will eventually put up my version of the circuit. For the moment, suffice to say that the typical Schoeps circuit, as shown in the other pages will work just fine.
This was the most difficult microphone to build thus far because of the body. After deciding on the shape and size of the body, I spent a couple hours scrounging for pieces of metal at Apex Electronics. I found a good piece of Brass tubing, along with aluminum discs, bars, etc. that I thought I could use to build the inside skeleton of the mic. Back home, I started hacksawing, and drilling. I finally bought a Dremel tool and that really made my life a lot easier on this project. They are 'must have's if you're going to do this sort of thing. Or anything, really...
I built the body,
then let epoxy do its thing, while I worked on the electronics.
Stuffing the perfboard. Don't start soldering till you've figured out if everything will fit. I also left an area open between the big film capacitors where I'd be able to drill a hole to then use as a mount to the skeleton frame below.
I used bits and pieces of scrap metal to build the inside of the microphone.
I drilled into the edge of some flat aluminum
which I then epoxied to the base. This would be what the shell would screw into
eventually.
To make sure I got everything right, I actually screwed these pieces into the
brass shell and put epoxy on them and then set the shell in place on the base. I
let them dry over night and then unscrewed and removed the shell, leaving the
pieces. I did the same with the vertical piece. I didn't want any ugly
surprises. That long screw in the top aluminum plate was just temporary. I
couldn't find a smaller screw when I took the pic!
With the circuit board attached. Two views - to give you some
perspective on the actual size.
The Capsule area. I struggled with this area for a while - couldn't figure
out exactly how I wanted to mount the capsule. I finally decided to do it this
way - rubber bands stretch across bent brass tube. The capsule is held by the
bands, which provide absorption
from vibration. It works pretty well, however, I will be building a different
mounting system soon - It will comprise of a brass ring that goes around the
capsule, and them mounts to a rubber shock mount.
Here you can see how the capsule is mounted.
Note this is actually the back of the capsule. You can see that the capsule
requires an external FET and 1Gig Resistor.
In this picture you can also see the sound damper (the same stuff I used in the
cardioids - a wet/dry vac filter) covering the aluminum plate. I used the
NT4416a fet. I will experiment with other fets soon as I actually prefer the
2N4338 in the SD cardioids.
Shape the Grille. Solder the edges together, and hide the seams with the body shell.
With the top and the grille on. Clean up (both the mic and my desk)
hadn 't
happened at this point.
A quick and dirty mounting system for the large guy. (to record some samples)
So - how do they sound?
Here are some clips with the two microphones you see above. Once again, I ask
for leniency on the music technique. I just whipped these clips out real fast.
These are two channel recordings with a tsb165a (16mm) capsule being the
comparison.
These recordings were made in my office, so don't expect studio conditions.
The microphones were fed into my GREEN PRE Preamp and then to my laptop. They
were recorded at 48k 24bit pcm and then compressed to 320k mp3s.
To truly hear the differences, I suggest separating the tracks, and listening to them as mono files. A/B listening this way reveals the differences.
My feelings with these two microphones (and they go along with standard audio
engineer thinking) - violin (strings) better with the SD. Voice - better with
the LD. Guitar... hmm.
With the violin, though they are more difficult to use, I tend to prefer the Omni microphones.
What do you think?
The Final product - with a proper shockmount
(which I bought on ebay for $15.00)