I've picked up a pair of Sterling Audio 151 microphones. They're an identical copy to the old M-Audio Nova down to the K67 style capsule and nasty HF. I was wondering about some ideas for mods. There is several posts about these microphones, but I'd like to maybe get some information here to clarify.
I want to tame the high end, and make them more usable for things like acoustic guitar, vocals and even possibly room mics and or guitar cabinet. I'm one for experimentation before asking for ideas, so that's exactly what I did.
The first things I did was replace C5 which was a 4.7uf 50v electrolytic with a quality Philips 1uF film cap. Next, I changed C1 which is the capacitor between the two 1G resistors by adding a 500pf silver mica in paralell. Next, I started looking for the output capacitor, which ended up being a 10uf electrolytic and I added a Wima 0.1uF in paralell to that as well. The microphones is now a "little" less bright and now seems to be too "boomy". Using coupling cap calculators and etc, that seems to be because the added 500pF to the input capacitor is letting more low-end through. I figured at that point, I could also replace the output 10uF with a quality Philips 1uF as well to help with the "boominess".
But, that got me to thinking about perhaps adding some HF attenuation (like in Neumann style circuits) or by possibly adding a LPF. What route would be better here? I've provided the schematic for the microphone foray help, please and thank you!
My idea for a LPF would be hanging a 0.1uF capacitor off the 200 Ohm resistor at the junction of the 10uF output capacitor and transformer leads. What issues would that cause? That would effectively put the 3dB cut-off at around 8kHz.
I've also seen where members line Ricardo, In67d and etc worked on implementing HF de-emphasis by adding a few components, removing the 1000pf input cap and etc and making the mic closer to the response of a u87 in cardiod only. That would require removing one 1G resistor, the 1nf input capacitor and adding two 1M resistors, a 330nf cap, a 220pf-470pf cap, 6k8 resistor and 12nf-22nf cap. Opinion on this?
The mic still is unpleasant in the high-end and is still boomy. What route would be best? Looking forward to any insight! As always, thank you so much for any help!
I want to tame the high end, and make them more usable for things like acoustic guitar, vocals and even possibly room mics and or guitar cabinet. I'm one for experimentation before asking for ideas, so that's exactly what I did.
The first things I did was replace C5 which was a 4.7uf 50v electrolytic with a quality Philips 1uF film cap. Next, I changed C1 which is the capacitor between the two 1G resistors by adding a 500pf silver mica in paralell. Next, I started looking for the output capacitor, which ended up being a 10uf electrolytic and I added a Wima 0.1uF in paralell to that as well. The microphones is now a "little" less bright and now seems to be too "boomy". Using coupling cap calculators and etc, that seems to be because the added 500pF to the input capacitor is letting more low-end through. I figured at that point, I could also replace the output 10uF with a quality Philips 1uF as well to help with the "boominess".
But, that got me to thinking about perhaps adding some HF attenuation (like in Neumann style circuits) or by possibly adding a LPF. What route would be better here? I've provided the schematic for the microphone foray help, please and thank you!
My idea for a LPF would be hanging a 0.1uF capacitor off the 200 Ohm resistor at the junction of the 10uF output capacitor and transformer leads. What issues would that cause? That would effectively put the 3dB cut-off at around 8kHz.
I've also seen where members line Ricardo, In67d and etc worked on implementing HF de-emphasis by adding a few components, removing the 1000pf input cap and etc and making the mic closer to the response of a u87 in cardiod only. That would require removing one 1G resistor, the 1nf input capacitor and adding two 1M resistors, a 330nf cap, a 220pf-470pf cap, 6k8 resistor and 12nf-22nf cap. Opinion on this?
The mic still is unpleasant in the high-end and is still boomy. What route would be best? Looking forward to any insight! As always, thank you so much for any help!
) - there are mounting holes that should fit the Nova (assuming the ST151 is also mechanically similar).
