Michael_Joly
Active member
- Joined
- Nov 11, 2004
- Messages
- 42
Years ago I built Dave's MXL/5840 mod. Love the sound but have never done much recording with it because of the noise. Here's some figures for S/N. What are you guys getting?
Test source: Tongue / teeth "click" (that fast transient sound made by pullling the flat surface of your tongue quicly away from the top of your front teeth) and normal level speaking voice.
I'm using a peak reading LED meter. Mic warmed up for 12 hours (more on this later)
I set the gain of the mic pre to read 0dB on the peak of the tongue click 2" from the capsule. My normal speaking voice comes in at -24dB at the same distance. Noise floor measures -56dB. I was recording a quiet singer yesterday, a 32dB S/N is just not going to be acceptable.
Noise is very LF and MF weighted - not hiss, a real rumble and crackle. My engineering notes from several years ago state "...this mic takes several days to warm up and settle down to a level that aproaches a solid state circuit".
I'm going to let it continue to sputter away for a couple of days and check it again to see how valid my old lab note is and if all the bad electrons have boiled off and the thing has settled down.
Should I swap tubes? Bad resistor noise? What have you guys found for this circuit? I noticed Mojave doesn't publish a noise spec for their 5840-based MA-200 mic.
Test source: Tongue / teeth "click" (that fast transient sound made by pullling the flat surface of your tongue quicly away from the top of your front teeth) and normal level speaking voice.
I'm using a peak reading LED meter. Mic warmed up for 12 hours (more on this later)
I set the gain of the mic pre to read 0dB on the peak of the tongue click 2" from the capsule. My normal speaking voice comes in at -24dB at the same distance. Noise floor measures -56dB. I was recording a quiet singer yesterday, a 32dB S/N is just not going to be acceptable.
Noise is very LF and MF weighted - not hiss, a real rumble and crackle. My engineering notes from several years ago state "...this mic takes several days to warm up and settle down to a level that aproaches a solid state circuit".
I'm going to let it continue to sputter away for a couple of days and check it again to see how valid my old lab note is and if all the bad electrons have boiled off and the thing has settled down.
Should I swap tubes? Bad resistor noise? What have you guys found for this circuit? I noticed Mojave doesn't publish a noise spec for their 5840-based MA-200 mic.