Re: Question for Pat


John M. Fiscella <profirst@...>
 

Message text written by INTERNET:QSIndustries@yahoogroups.com
Pat said:
Your expeirment sounds totally worthwhile.
The results will be a bit uncalibrated and perhaps a bit subjective -
but, it is way better than what we have now - nothing. I am looking
forward to a description of your experiences. Thanks!<

Pat, I too am worried about subjectivity entering into the listening. I
thought about various ways to counteract this, like letting someone else do
the stuffing and then verify the differences blindfolded (the so-called
double-blind test like they do with medications). The other thing is that
the sound must be set at the same level for each loco prior to stuffing.
That I can do: I have a digital sound level meter. Maybe I will enlist the
help of a few Club members. We have 9 Club members with BLI or Lionel
locomotives, a total of probably 20 or so (I have 6). I'm sure they would
be interested in helping. If this experiment improves the already-good
steam sound even one iota, they probably will also stuff their tenders
(provided, that is, after BLI or QSI says it is safe to do so).

It may also be possible to take 2 readings with the SLM using two
weightings (choosing from A, B and C) both before and after stuffing. That
might objectively indicate a difference. A "weighting" means that the
frequency response of the microphone on the SLM is electronically altered
so that it reads the sound spectrum differently. The difference of 2
readings taken with 2 weightings is an indicator of the shape of the sound
spectrum being measured. If the difference changes between empty and
stuffed tenders (along with an audible difference) that can be related back
to the difference in frequency response of the system being measured across
2 bands.

Ciao!
John F. in California

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