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previous: Stephen Giles Well, I saw 3 of the most respected... -- 2/5/2001 1:49 PM View Thread

Re: Sony Minidisc record level - again!

2/6/2001 4:35 AM
Steve F
Re: Sony Minidisc record level - again!
Are you recording live with mics? (sorry,  
missed the previous thread.) It sounds like  
what you're after is to be able to control the  
level of signal coming into your MD recorder?  
Couple of ideas, although I would not aspire to  
rocket science:  
It surprises me that the pots were not quiet enough  
to be used in a passive attenuator type situation.  
My first impulse would be to try again with better  
pots. Maybe you could rob some faders off a junk  
PA board or something. Or if you have a busted up pedal with a couple of knobs on it, gut it and try again using the pots from the pedal. (Just don't do  
like I did once and hack up a Fuzz Face. AAACK..)  
If you are using balanced output dynamic mics, you could try using a pot as a variable R between the two signal leads to attenuate the signal without the  
resistor being in the signal path. If you're recording off some kind of active circuitry this is  
not a good idea.  
If it's more of a "set & forget" application, you  
could use a couple of rotary switches to build a  
stepped attenuator in lieu of the pots. As long as  
you don't need to trim something in mid-performance  
this would work well and be quieter than the average  
If it's REALLY a set & forget, I think Shure makes  
fixed, inline attenuators that attach in between the mic cable and input. Or you could build some little modular boxes yourself using just resistors and jacks.  
Or you could build a pair of little op-amp based  
mic preamps, and put a pot in the feedback loop  
to adjust the gain. If you need to pad the input  
you could build a voltage divider attenuator at  
the input. In Walter Jung's book, "IC Audio Op-Amp  
Applications", he describes a couple of varieties.  
You'd have to use the right op-amps or it could  
get pretty noisy in its own right.  
There are a couple of companies, like Rolls, that  
make really inexpensive, passive mixers (I think they go for around $25 or so, but I could be wrong)  
that could be modified for stereo output. Some of  
these are about the size of a pack of cigarettes.  
Or, if you don't mind spending a few bucks, do what I did and get a stereo mic preamp with separate controls. The PreSonus Blue Tube ($169 mail order)  
is reputed to be a great value - I use two ART  
MP's for the occasional live stereo recording, with  
decent results, but I hear the PreSonus is much  
nicer and cheaper to boot.  
Hope this is some help.  
Steve F.