[sdiy] coupler module2

[Czech Martin]

The 10mV example was certainly exagerated,
it should just illustrate
"why are there so many different levels"
and "why is there a need for scaling"
as somebody has asked.

So , really you have something between 300mV/1V and 13V,
which is still a lot (~ 33dB / 22dB).

Somewhere I read that dBu and dBv is sometimes the same
(from the old times, when the letter v was equal for u
 and vice versa, roman empire).

dBu seems to refer to 0.775 V RMS, sometimes written as dBv
dBV seems to refer t0 1.000 V RMS

After all, there is no science in it, just calculating with logarithms
and some definition of the reference level.

If you go to digital recording, a peak meter is a must.
A 10 min recording is easily noticeable spoiled from 10ms overdrive,
since there is no headroom above full scale.
So a comparator with some storage device to light a red
LED is a good idea, if you do not want to look constantly
at the meter for 10 min.

m.c.

> -----Original Message-----
> From: jhaible at debitel.net [mailto:jhaible at debitel.net]
> Sent: Dienstag, 26. August 2003 14:06
> To: Czech Martin
> Cc: Peachey, Dave; Sdiy (E-mail)
> Subject: RE: [sdiy] coupler module2
> 
> 
> > E.g. a cascade filter will need small signal levels,
> > like 10mV, this is also true for other structures
> > wich use "linearised" junctions as variable gain circuits.
> 
> You will *never* want to run 10mV signals over patchcords.
> Always amplify them to 1V at least at the module output
> and attenuate it again at the module input.
> Otherwise your ground will "bypass" some of the unfiltered
> signal (in case of the module being a filter).
> And pick up hum like hell, of course.
> 
> JH.
> 
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