Question for Pat


Jon Miller <atsf@...>
 

Question for Pat.
Could you tell me the ohm rating on the speakers. It appears they are
wired in series so was curious if they are 8 ohm. I wish to try a different
(higher quality) speaker/s with one of my units.
I also would like to know the power output of the amp if it's not
classified<G>.
I bought an engine just to play with.

Jon Miller
AT&SF
For me time has stopped in 1941
Digitrax, Chief/Zephyr systems, JMRI user
NMRA Life member #2623
Member SFRH&MS


Pat Quinn <quinn1947@...>
 

Jon,

Our designs generally use 2 8-Ohm speakers in series.
A single speaker would be 16 Ohms. You are unlikely to cause damage
to the ASIC with loads down to 4 Ohms - though 8 Ohms might be a
safer idea. There are other components (such as supply regulators)
to consider. Expeirmentation is good - but, QSI does not encourage
modifying the design because of warranty issues.

I'm not sure what you're after. It is likely volume or bass
response. Typically your most important design variable is baffeling
(treatment of front/back wave mixing.) Larger size is generally
better for base response and volume. Often bass response and volume
don't go together in a speaker of a given size and shape. Another
consideration is that distortion and volume work against each other
for a given speaker. QSI strives for a balance of many factors in
its design. There may be expensive speakers that have some
improvement over more moderately priced ones. You may enjoy a
different solution space than what QSI has selected. I would love to
hear about any expeirmentation going on. Good luck!


Generally, the products that manufacturers develop are a compromise
of cost and performance on a wide range of issues. Individual
modelers may be able to enjoy improvements through customization
that don't pencil in for a market in general.

-Pat


-------------------------------------------------------------

--- In QSIndustries@yahoogroups.com, "Jon Miller" <atsf@i...> wrote:
Question for Pat.
Could you tell me the ohm rating on the speakers. It appears
they are
wired in series so was curious if they are 8 ohm. I wish to try a
different
(higher quality) speaker/s with one of my units.
I also would like to know the power output of the amp if it's
not
classified<G>.
I bought an engine just to play with.

Jon Miller
AT&SF
For me time has stopped in 1941
Digitrax, Chief/Zephyr systems, JMRI user
NMRA Life member #2623
Member SFRH&MS


Jon Miller <atsf@...>
 

I'm not sure what you're after. It is likely volume or bass response<
Not volume but bass. The general favorite speaker is a Intervox
S11X16VNS (8 Ohms). This speaker is sold by the various sound decoder folks
with different names. Given the size this is a very good speaker for bass.

but, QSI does not encourage modifying the design because of warranty
issues.<
I do realize this. I bought an engine simply for the sound unit to play
with. Anyone want a heavy 2-8-2 that just runs on DC, without sound<VBG>.

Generally, the products that manufacturers develop are a compromise
of cost and performance on a wide range of issues<
While in volume this speaker is not very expensive (couple of bucks)
it's probably higher than the regular speakers QSI uses. It is also quite
large which would make it difficult to use in the normal QSI package. As
the frame is styrene it's easy to glue a speaker baffle on it and they sound
very good.
If it turns out to be a solution for bass I will let you know and maybe
post pictures. However as QSI is not going to sell individual modules I
doubt many will do this.

Jon Miller
AT&SF
For me time has stopped in 1941
Digitrax, Chief/Zephyr systems, JMRI user
NMRA Life member #2623
Member SFRH&MS


John M. Fiscella <profirst@...>
 

Message text written by INTERNET:QSIndustries@yahoogroups.com
Jon said:
I'm not sure what you're after. It is likely volume or bass response<
Not volume but bass. The general favorite speaker is a Intervox
S11X16VNS (8 Ohms). This speaker is sold by the various sound decoder
folks
with different names. Given the size this is a very good speaker for bass.

but, QSI does not encourage modifying the design because of warranty
issues.<
I do realize this. I bought an engine simply for the sound unit to
play
with. Anyone want a heavy 2-8-2 that just runs on DC, without sound<VBG>.

Generally, the products that manufacturers develop are a compromise
of cost and performance on a wide range of issues<
While in volume this speaker is not very expensive (couple of bucks)
it's probably higher than the regular speakers QSI uses. It is also quite
large which would make it difficult to use in the normal QSI package. As
the frame is styrene it's easy to glue a speaker baffle on it and they
sound very good.<

I am sure that one of the parametric restrictions of the QSI chassis is
that the speakers used are the same units for most (steam) locomotives. But
different steam locos sounded different (the puck-puck-puck of the SP
Mikados ("chickens") to the book-book-book of the PRR K-4's to the
woof-woof-woof of the NYC J-1e Hudsons. And this is despite the differences
in the sound and the different enclosuire volume created by the various
tenders. It also helps to stuff the enclosure with cotton or glass fibre in
the remaining space between the electronics and the speaker units. This is
not done by QSI. Also, the mass of the cones can be increased by globbing
on some felt or solid which adds weight. The higher the moving mass, the
lower the resonant frequency of the system. Usable bass response in an
effectively infinite baffle system is roughly 1/2 octave below the system
resonant frequency. A vented system has less extension. Whether a
locomotive tender more closely represents an infinite baffle or a vented
enclosure needs to be determined. If there is a significant hole through
which air escapes, then a vented enclosure results, possibly with the
double resonances of a typical vented system. Adding mass to the cone would
not help in this case.

John F. in California


bobspf
 

Having been in acoustics in one of my distant past lives, this reminder was
tempting for a moment, but I have had some shortened lives of decoders
without enough free air to dissipate heat.

Bob Zoeller

----- Original Message -----
From: "John M. Fiscella" <profirst@compuserve.com>
. It also helps to stuff the enclosure with cotton or glass fibre in
the remaining space between the electronics and the speaker units. This is
not done by QSI.


Jon Miller <atsf@...>
 

It also helps to stuff the enclosure with cotton or glass fiber in
the remaining space between the electronics and the speaker units<
I have been told that the use of the above materials will eventually
cause them to "shed?" especially glass fiber. It was suggested to use poly
fill from an old pillow or other source.

Jon Miller
AT&SF
For me time has stopped in 1941
Digitrax, Chief/Zephyr systems, JMRI user
NMRA Life member #2623
Member SFRH&MS


Jon Miller <atsf@...>
 

but I have had some shortened lives of decoders without enough free air to
dissipate heat.<
While I have done no tests at all I did notice that the tender was just
slightly warm when I picked it up to put it on the bench. It had been
running about 10 minutes. I do suspect this unit gets warm. To be safe I
think it's better to enclose the speaker which is easy to do with the
Intervox.

Jon Miller
AT&SF
For me time has stopped in 1941
Digitrax, Chief/Zephyr systems, JMRI user
NMRA Life member #2623
Member SFRH&MS


John M. Fiscella <profirst@...>
 

Message text written by INTERNET:QSIndustries@yahoogroups.com
Jon said:
I have been told that the use of the above materials will eventually
cause them to "shed?" especially glass fiber. It was suggested to use poly
fill from an old pillow or other source.<

Yes, that is a better, hi-tech material to use. In the olden days before
poly-fill, sometimes the filling would be enclosed in a cloth bag to
prevent shed. But apparently, most speaker mfgrs. have been unconcerned
about shed. Evidently, it does not clog the speaker driver mechanism.

John F. in California


John M. Fiscella <profirst@...>
 

Message text written by INTERNET:QSIndustries@yahoogroups.com
Bob said:
Having been in acoustics in one of my distant past lives, this reminder
was tempting for a moment, but I have had some shortened lives of decoders
without enough free air to dissipate heat.
<

That may be why it wasn't done. Pat, can you comment on that?

John F. in California


Pat Quinn <quinn1947@...>
 

For the most part, the air closest to the elctronics is "dead" air
(i.e. not moving). It is a matter of time (minutes) before the air
closest to the boards is at a mostly stable temperature. The primary
heat sinking is done with the mounting bracket. I would guess that
back fill would not damage heat sinking too much - though wrapping
something hot in a wool blanket is not going to make it cooler <g>.
Reliability is something that manufacturers must be very cautious
with. If some of you would report your findings, it might lead a
manufacturer to consider fill to increase apparent back-wave air
density.
I think there is the unknown of how much improvement does the
backfill really provide. I'd love to hear a couple of mp3 files from
someone who tried this in an A/B test on the same engine. We can
post such files directly to the Group (under "Files")

-Pat
QSI

------------------------------------------------


--- In QSIndustries@yahoogroups.com, "John M. Fiscella"
<profirst@c...> wrote:
Message text written by INTERNET:QSIndustries@yahoogroups.com
Bob said:
Having been in acoustics in one of my distant past lives, this
reminder
was tempting for a moment, but I have had some shortened lives of
decoders
without enough free air to dissipate heat.
<

That may be why it wasn't done. Pat, can you comment on that?

John F. in California


John M. Fiscella <profirst@...>
 

Message text written by INTERNET:QSIndustries@yahoogroups.com
Pat said:
I think there is the unknown of how much improvement does the
backfill really provide. I'd love to hear a couple of mp3 files from
someone who tried this in an A/B test on the same engine. We can
post such files directly to the Group (under "Files")
<

Pat, I have two synchronized BLI J-1e Hudsons (different numbers and
different weathering). I could backfill one, run them together, and see if
it makes any difference in the sound, and report back. Making MP3 files
would require setting up microphones to record, with its plethora of
pandora's box acoustical issues.

John F. in California


Pat Quinn <quinn1947@...>
 

John,
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

-------------------------------------------------------------

--- In QSIndustries@yahoogroups.com, "John M. Fiscella"
<profirst@c...> wrote:
Message text written by INTERNET:QSIndustries@yahoogroups.com
Pat said:
I think there is the unknown of how much improvement does the
backfill really provide. I'd love to hear a couple of mp3 files
from
someone who tried this in an A/B test on the same engine. We can
post such files directly to the Group (under "Files")
<

Pat, I have two synchronized BLI J-1e Hudsons (different numbers
and
different weathering). I could backfill one, run them together,
and see if
it makes any difference in the sound, and report back. Making MP3
files
would require setting up microphones to record, with its plethora
of
pandora's box acoustical issues.

John F. in California


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


denlippert <denlippert@...>
 

I would certainly be happy to hear that some poly-fill could
eliminate the "hollowness" of the Hudson's sound. (which brings up
other thoughts of "damping" materials that could be applied to the
inside of the shell... helping to damp the sound, and still allowing
airflow around the QSI electronics....

Den


--- In QSIndustries@yahoogroups.com, "Pat Quinn" <quinn1947@y...>
wrote:

John,
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

-------------------------------------------------------------

--- In QSIndustries@yahoogroups.com, "John M. Fiscella"
<profirst@c...> wrote:
Message text written by INTERNET:QSIndustries@yahoogroups.com
Pat said:
I think there is the unknown of how much improvement does the
backfill really provide. I'd love to hear a couple of mp3 files
from
someone who tried this in an A/B test on the same engine. We can
post such files directly to the Group (under "Files")
<

Pat, I have two synchronized BLI J-1e Hudsons (different numbers
and
different weathering). I could backfill one, run them together,
and see if
it makes any difference in the sound, and report back. Making MP3
files
would require setting up microphones to record, with its plethora
of
pandora's box acoustical issues.

John F. in California


John M. Fiscella <profirst@...>
 

Message text written by INTERNET:QSIndustries@yahoogroups.com
I would certainly be happy to hear that some poly-fill could
eliminate the "hollowness" of the Hudson's sound. (which brings up
other thoughts of "damping" materials that could be applied to the
inside of the shell... helping to damp the sound, and still allowing
airflow around the QSI electronics....
<

Damping materials would also help the Hudson: one of mine has the tender
walls buzzing. But damping material to help absorb the backwave of a
loudspeaker should entirely fill the space behind it for maximum effect.
That is what I aim to test.

John F. in California


Pat Quinn <quinn1947@...>
 

A thought: if the difference is so minute that it takes double-blind
tests to protect objectivity, chances are, the difference is
negligible. Any significant improvement should be somewhat apparent
(one hopes.) Thanks for doing this. Roger about the weighting -
especially if you know what the weightings are. We (at QSI) are
constantly working on ways to get the best sound out of a given
cavity.
-Pat


--- In QSIndustries@yahoogroups.com, "John M. Fiscella"
<profirst@c...> wrote:
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


John M. Fiscella <profirst@...>
 

Message text written by INTERNET:QSIndustries@yahoogroups.com
A thought: if the difference is so minute that it takes double-blind
tests to protect objectivity, chances are, the difference is
negligible. Any significant improvement should be somewhat apparent
(one hopes.) Thanks for doing this. Roger about the weighting -
especially if you know what the weightings are. We (at QSI) are
constantly working on ways to get the best sound out of a given
cavity.<

Pat,

does QSI do frequency response measurements of a locomotive in an anechoic
chamber or outdoors (a poor-man's equivalent)? If measurements (using a
"real time analyzer") are done outdoors, the loco should be hung on a pole
at least 25 feet off the ground. The idea of measuring outdoors or in an
anechoic chamber is to remove the boundary effects from floors, walls,
layout, etc. in order to really determine what the intrinsic frequency
response is. Boundary effects usually alter bass response below 200 Hz. Of
course, if the QSI speaker systems in locos don't produce any substantial
output below 200 Hz, then measurement indoors is OK.

In order to scientifically optimize the sound system, QSI should buy/rent a
real time analyzer and good condenser directional microphone. The output of
the RTA can be put into a computer to visualize the frequency response.
Then, when a change is made to the QSI system, a curve is rerun. Acoustic
design is always part science and part art; so repeat measurements are a
technique of importance in getting good sound. Just adding a little weight
to a speaker cone, for example, using a drop of glue, *could* make a
profound difference in the audible sound. And also, the production
variation between identical speakers is typically enough to produce good
sound on one loco and terrible sound on another of the same type. So each
speaker unit must be tested to be within an acceptable tolerance. If it
does not fall within the tolerance, it is thrown out and never used for
assembly.

John F. in California


John Burkhardt <johnb@...>
 

John,

Both my BLI SF 4-8-4 and Heavy Mikado suffered from distortion due to tender
side wall flexing. My remedy was a piece of the foam rubber from an Athearn
blue box cut to length to wedge between the side walls.

Thanks and regards,

John Burkhardt
South Africa
where the sun always shines,
and steam still reigns!

----- Original Message -----
From: "John M. Fiscella" <profirst@compuserve.com>
To: <QSIndustries@yahoogroups.com>
Sent: Tuesday, December 07, 2004 10:12 PM
Subject: [QSIndustries] Re: Question for Pat



Message text written by INTERNET:QSIndustries@yahoogroups.com
I would certainly be happy to hear that some poly-fill could
eliminate the "hollowness" of the Hudson's sound. (which brings up
other thoughts of "damping" materials that could be applied to the
inside of the shell... helping to damp the sound, and still allowing
airflow around the QSI electronics....
<

Damping materials would also help the Hudson: one of mine has the tender
walls buzzing. But damping material to help absorb the backwave of a
loudspeaker should entirely fill the space behind it for maximum effect.
That is what I aim to test.

John F. in California




Yahoo! Groups Links








Steven Orth
 

John wrote:

The idea of measuring outdoors or in an anechoic chamber is to remove the boundary effects from floors, walls, layout, etc. in order to really determine what the intrinsic frequency response is. Boundary effects usually alter bass response below 200 Hz.<<
John:

I understand the concept of testing speakers in an anechoic chamber. However, I would interject that we don't listen to our locomotives in an anechoic chamber, and therefore evaluation of the "system" (driver, enclosure, damping, venting, crossover) should be done in the environment in which the system is used. Reflections off the surface that the loco is setting on are significant and will make a difference. On my layout, I have a through truss bridge with an open deck. When a sound equipped loco goes over the bridge, the volume and frequency content of the sound changes significantly, enough so that you can hear it from 10ft away. Adding damping material to the enclosure will change the "q" of the system, and may change the frequency spectrum of the system's output.

I would perform the comparison tests on ballasted track with scenery around the track for a few feet. I've got three Lionel Challengers and three turbines. I may play with this some also.

Steve Orth


John M. Fiscella <profirst@...>
 

Message text written by INTERNET:QSIndustries@yahoogroups.com
The idea of measuring outdoors or in an anechoic chamber is to remove
the boundary effects from floors, walls, layout, etc. in order to really
determine what the intrinsic frequency response is. Boundary effects
usually alter bass response below 200 Hz.<<

John:

I understand the concept of testing speakers in an anechoic chamber.
However, I would interject that we don't listen to our locomotives in an
anechoic chamber, and therefore evaluation of the "system" (driver,
enclosure, damping, venting, crossover) should be done in the environment
in which the system is used. Reflections off the surface that the loco is
setting on are significant and will make a difference. On my layout, I
have a through truss bridge with an open deck. When a sound equipped loco
goes over the bridge, the volume and frequency content of the sound changes
significantly, enough so that you can hear it from 10ft away. Adding
damping material to the enclosure will change the "q" of the system, and
may change the frequency spectrum of the system's output.

I would perform the comparison tests on ballasted track with scenery around
the track for a few feet. I've got three Lionel Challengers and three
turbines. I may play with this some also.

<