Thanks for the welcome and comments. I appreciate it very much!
Great suggestions, some that I haven't even thought of. Keep 'em coming.
BTW, this mic preamp design works with dynamic mics, condenser mics, FET condernser mics, tube mics and ribbon mics. No problem with gain settings or operation on any of them. (Check out MIX magazine May 2008 issue, this mic pre design was used in the gear review of a Peluso vs. Neumann mic.)
2 channel and or four channel versions I think my PSU can handle that (2 ch). The current consumption of the mic preamp is only +/-17mA. (And 5mA of that is being used by the LED phantom power lamp, otherwise it's only +/-12mA)...
and YES, it runs internally on +/- split rail voltages. About 30V+ peak to peak voltage. Plus TRUE +48V for the phantom power.
in a as small as possible metal case say 9"x7"x2" say brushed AL. or black AL.Noted. ... The case I'll be using is 6" x 4" x 1.5" and an option for 6" x 4" x 2.5"... single channel, extruded aluminum (not plastic), with anodized aluminum front and rear panel.
first Variable knob for +or- 10 dbI'm using a high-quality Bourns sealed potentiometer, conductive plastic... (will not get dusty, scratchy or worn out like carbon pots). It functions as a "trim/volume knob"... from cutoff to 0dB (i.e. no trim).
second indented knob in 10db increments from 6 to 76DB give or takeI'm using a high-quality sealed Grayhill 12-step, 1-deck selector switch. Gain adjustment is 6dB increment in 12 steps, from +6dB to +72db gain (balanced out). If unbalanced output, it will be from 0dB to 66dB gain.
Runs on anything from 6volt to 12 voltCheck. Done.
XLR input switchable line level to mic levelThe current mic inputs can be used as line level inputs. Just set the gain switch down to 6dB.
XLR outputs and RCA outputs.I think this is doable. Just need another jack. My balanced line driver stage behaves well with single-ended loads.
Good LED metering.What is the definition of "good"?
I have a separate VU meter kit, but it only has 5 LEDs. Will run from 4V to 24VDC input (has on-board regulator).
if an LED VU is required, the 2.5" case height is probably needed.
Recessed front panel so knobs aren't acidently bumpedGood idea. I think this is more on the chassis/case construction... so need something to "guard" the knobs from being adjusted accidentally. I have to think about this one.
power switch on the front panel not the backHmmm... I don't have this. Need to add a power switch.
ability to turn phantom power on or off for dynamic mics or ribbonsDone... and my phantom power is a soft start. The 48Volts is ramped up gradually from 0V to 48V over a span of few seconds. So there is no big THUD when you turn on/off phantom power. Same thing when you turn it OFF, no big THUD... it's decayed down from 48V to 0V.
and very low noise floor at maximum gain.......Is this good enough?
http://www.fivefishstudios.com/audio/SC1Solo-NoiseTest.mp3Oh yes a fair price.....it can't break the bank.....tapers aren't rich but will spend for a good reliable product.I think the most common pre is the SoundDevices pre for tapers, is that right? Or do most go the DIY approach?
I don't have any pricing on this yet... still need to get quotes for extruded aluminum case with anodized front and rear panel.
QUESTION:
Is needing an external battery pack a big deal or a deal breaker? I don't have room for an internal battery. Hmmmm....
At the moment, this just a single channel mic preamp. In the future I'll be converting this to SMD and cut the size further in half, or cram 2 channels on the same board. But that's a far future.
Thanks for the comments.