HDTenEightyP/NetNews huggingface dataset:
From: demaine@ee.ualberta.ca (Cal Demaine)
Subject: Re: VOLTAGE CONVERTER
Organization: University Of Alberta, Edmonton Canada
Date: Thu, 16 Apr 1992 20:49:08 GMT


>In series, if the resistance of the two resistors is equal, they will both 
>get half the voltage.  In parallel, the voltage will be the voltage of the 
>power supply for both resistors, assuming that the power supply can handle 
>the parallel load.  There are separate sets of equations for series and 
>parallel.  Check out a physics book at the library for the formulas :-)

>S. Graham

Ok, before I say anything, IMHO you should go to an electronics dealer and
buy a voltage regulator w/big heatsink before you even attempt to balance
any of this with resistors.

But anyway, here's the formula:

  V= Input voltage, I= Input current
  V1= voltage across resistor 1  I1= current through resistor 1
  V2= voltage across resistor 2  I2= current through resistor 2
  R= total resistance.

  Two resistors in series, R1, R2.

  I=V/(R1+R2)  I1=I2=I  R=R1+R2  V1=I*R1  V2=I*R2

  Two resistors in parallel.

  R=1/(1/R1+1/R2)  I=V/R  I1=V/R1  I2=V/R2  V1=V2=V

Beyond here lie dragons:

  Let's suppose (quite reasonably, for this example) that your little VW bug
radio has a power consumption of... 12 watts.  Power=V^2/R, giving us R=3ohms.
If we use R as R1, then R2 would have to be 3ohms as well, and would also
dissipate 12 watts (ouch!)  But it can be done no problem.

  But let's say that, suddenly (big, musical peak on your radio), your radio
draws 18 watts.  P=V^2/R, and R has become 2ohms!  The battery now sees 3ohms
(resistor) and 2ohms (stereo) = 5ohms.  Therefore, I=2.4, and the voltage
across your radio becomes 4.8V instead of 6.0V.  Chances are, it's not going
to work too good with that low a supply voltage.

  Of course, the above example is simplified a bit, but hopefully it does
demonstrate that resistor balancing is *not* the way to go with loads that
you are unsure of, be them unspecified, or able to change.

  Which, of course, is why they came along with power electronics...

  -- Cal
Newsgroups: rec.audio.car
From: chenh@athena.ecs.csus.edu ( h philip chen )
Subject: Re: Going Through the file wall
Organization: California State University, Sacramento
Date: Fri, 17 Apr 92 08:59:35 GMT

dsg6397@cs.rit.edu (David S Greenberg) writes:
>
>	I was wondering if anyone knows:  Is there some trick to routing
>power / ground cables from the engine compartment through the fire wall
>and into the car interior. I spend a long time trying to find an existing
>hole big enough to route 2 10 ga. cables through. I ended up drilling a 
>hole (what a bitch!!!) and worrying about hitting something important.
>	It ended up working out ok, but I figure there must be an easier
>way!

as for me, i found a factory wire bundle under the dashboard, going 
through the firewall but i couldn't squeeze the fat cables through
there.  instead i used it as a reference point and drilled two holes 
next to it.  (actually it was pretty close to the hydraulic brake 
lines in the engine bay but that was my only choice there.  luckily i 
didn't hit anything but i was already sort of sure that i'll miss it.


regards,

-philip
From: louis@tronix.SignalPath.on.ca (Louis Bertrand)
Subject: Radio-Elec. April/92
Newsgroups: rec.audio.car
Date: 7 Apr 92 17:25:31 GMT
Distribution: world
Organization: Signal Path Designs


Well, it appears I was asleep at the switch and didn't get
to the bookstore on time.

The April issue, with the car stereo amp project, was replaced
by the May issue, taken off the shelves and shredded by the
local news/magazine distributor...

I'll search local libraries, but I haven't seen the magazine 
there previously.

Could some kind soul please photocopy and postal mail it to me?
(Copyright does not apply, this is non-commercial).

e-mail me to get the postal address and avoid multiple sends.

Thank you much
 -- Louis
--
Louis Bertrand   *   Lynden, Ontario, Canada   *   (416) 648-8066
Signal Path Designs (Analog - Digital - Audio - Embedded uCs)
louis@SignalPath.on.ca (new -- may not work yet)
louis%tronix@maccs.dcss.mcmaster.ca (old -- still works fine)
From: david@ganglion.ann-arbor.mi.us (David Hwang)
Newsgroups: rec.audio.car
Subject: Acura Legend Systems
Date: 6 Apr 92 22:01:46 GMT
Reply-To: david@ganglion.ann-arbor.mi.us
Organization: D.J. Services

Has anyone seen/heard any impressive systems installed into an 
Acura Legend (1991 or 1992)?  What components were used and
where were they mounted?  E-Mail replies appreciated.

David Hwang

-- 
David W. Hwang     [david@ganglion.ann-arbor.mi.us]  |  "Friends come and go.
3000 Glazier Way, #260                 313/665-0555  |   Enemies accumulate."
Ann Arbor, Michigan           U of M Medical School  |  "I'm *not* amused..."
From: koziarz@chinet.chi.il.us (Louis Koziarz)
Newsgroups: rec.audio.car
Subject: Looking for discman->FM gadget
Date: 16 Apr 92 18:56:54 GMT
Article-I.D.: chinet.1992Apr16.185654.6286
Distribution: usa
Organization: Chinet - Public Access UNIX

I'm trying to find a gadget that takes a walkman-type jack output and
transmits it to an FM frequency, usually through the cigarette lighter.
I've seen these in a few places, but now that I want one I can't find them
anywhere.  Does Crutchfield carry them?  Help!      
 

-- 
Louis Koziarz
koziarz@chinet.chi.il.us
From: harner@test1.dab.ge.com (Keith Harner)
Newsgroups: rec.audio.car
Subject: Re: enclosure questions
Date: 8 Apr 92 00:53:43 GMT
Organization: General Electric SCSD, Daytona Beach FL

In article <1992Apr3.030657.507@ncsu.edu> blaine@catt.ncsu.edu (Greyland Blaine Mull) writes:
#I have a porting equation that is right on the money already, i just
#need the equation for the volume - any takers?

The optimum internal volume for a ported enclosure is given by:

  Vb = 15 * Qts ^ 2.87 * Vas

  The optimum internal volume for a sealed enclosure is given by:

         Vas
  Vb = -------------
         0.7
       ( --- )^2 - 1
         Qts


--
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
|Keith Harner                                   |harner@civax.DAB.GE.COM     |
|General Electric Simulation and Control Systems|harner@sunny.DAB.GE.COM     |
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
From: yystg@lims01.lerc.nasa.gov (STEVE GRAHAM)
Newsgroups: rec.audio.car
Subject: Re: Speaker Connections
Date: 17 Apr 92 14:13:00 GMT
Article-I.D.: lims01.17APR199209133627
Organization: NASA Lewis Research Center
News-Software: VAX/VMS VNEWS 1.41

In article <1992Apr16.054144.5644@scott.skidmore.edu>, jreiser@scott.skidmore.edu (jason reiser) writes...
>	I went out on a limb and assumed that he would know which
>wires went to which speakers since he installed those wires himself.
>Thanks for the advice on the dangers of this method though.  From my
>experience, it's always best to do all the electrical wiring first and
>then do the speakers.  Tends to avoid that scenario.
> 
>				- Jason
> 
I don't think you went out on a limb.  As I remember, the original poster 
did know which wires were the speaker wires, it was just that he used the 
same color/type of wire for both + and -.  In this case, your suggestion 
was excellent, IMO.

S. Graham
Newsgroups: rec.audio.car
From: jreiser@scott.skidmore.edu (jason reiser)
Subject: Re: VOLTAGE CONVERTER
Organization: Skidmore College, Saratoga Springs NY
Date: Wed, 15 Apr 1992 21:22:21 GMT

mitch.blades@cccbbs.UUCP (Mitch Blades)  writes:
> NG>   I have a 6 volts VW car radio which I would like to run on my new
> NG>12 volt battery car.  I want to build a 'voltage converter' that would allow
> 
> Well I'd try a resister myself.. just go to radio shack..
> 


Even easier, while you're at Radio Shack, just ask for a 12volt to 6
volt converter.  I know that they DID make these, as my local store
has a surplus they've been putting "On Sale" for the last year.  It's
really cheap too.  Of course, you miss out on the satisfaction of
building it yourself, but this will get the job done.

				- Jason Reiser
Newsgroups: rec.audio.car
From: frank@owlnet.rice.edu (Franklin Tae-Sung Kang)
Subject: Re: Amp schematic request
Organization: Rice University
Date: Wed, 8 Apr 1992 09:51:56 GMT

In article <10842095@tronix.SignalPath.on.ca> louis@tronix.SignalPath.on.ca (Louis Bertrand) writes:
>frank@owlnet.rice.edu (Franklin Tae-Sung Kang) writes:
>> Check out Radio Electronics, April 1992.  It has schematics for 
>> a 200wpc(I think) power amp.  I briefly looked over the design and
>> it looked ok.  Only thing I was concerned about was the somewhat
>> small package for a powerful amp (heatsink area that is).
>> 
>> Louis Bertrand, I don't suppose you've looked at it?  How about an
>> expert opinion?
>
>I'll check it out as soon as I can and keep you posted...
>BTW, heatsink area is ALWAYS too small in a car stereo amp, as long
>as we can't put 19-inch racks in our automobiles...

Ok, that would be great.  I'm curious, how much of the heatsink is
needed for the acutual output transistors and how much is needed
for the power supply?  The heatsink problem doesn't seem to be as
bad as soom home receivers though.  For example my JVC 100wpc has
one aluminum internal heatsink about the size of a 25wpc Alpine
amp I used to own.  I'm planning to build a project from Audio
Amateur (40wpc Class A amp by Nelson Pass) - it will have about
8 heatsinks the size of forementioned amp. :-)

Frank


-- 
Frank T. Kang-------------------------------------------------frank@rice.edu
"...if there was a doubling of the current engineering enrollment-the growth 
rate of the economy would rise 0.5% a year.  By contrast, if law school
enrollment doubled, the growth rate would fall 0.3% annually."  BW 4/6/92
From: yystg@lims01.lerc.nasa.gov (STEVE GRAHAM)
Newsgroups: rec.audio.car
Subject: Re: Damping Factor in amplifiers.
Date: 15 Apr 92 16:25:00 GMT
Article-I.D.: lims01.15APR199211253126
Organization: NASA Lewis Research Center
News-Software: VAX/VMS VNEWS 1.41

Damping factor is now considered to be about as usefull as THD in 
determining what an amp can do.  Consider that the resistance of the wires 
used to hook up your amp to the speakers will add enough resistance to 
nullify an "excellent" damping factor.  The only way to really tell if an 
amp effectively damps a certain load/speaker is to try it out.  The numbers 
don't say much.  The damping factor is usually rated at the speaker outputs 
on the amp - a good rating there can turn into a lousy one at the speakers.

Personally (IMO) a damping factor does not tell much about the ability to 
control a speaker.  This opinion is supported by most of the stereo/audio 
mags out today.  It can almost be discounted as simply a buzzword to get 
people's attention.

What I'm saying is that the number of the damping factor is pretty useless 
if you add in the speaker wires, connections, etc.  It may give a general 
indication of how the amp will perform, but given the fact that the 
resistance of the wires will destroy the number, the stress on the damping 
factor of an amp is overkill.  How it performs when hooked up to a 15 or 18 
inch woofer is important. (or 12 inch or 10 inch or 4 - 10 inch.....)

As with all audio equipment, performance, not numbers, is the only thing to 
look for.  There are exceptions, but this is a very good general rule to 
follow, especially if you don't know what the numbers mean or better yet, 
what they _don't_ mean :-)

S. Graham
From: rslau@usc.edu (Robert Lau)
Newsgroups: rec.audio.car
Subject: Re: WeenieBox! [was: Re: DSP for automatic Volume Control]
Date: 15 Apr 1992 12:22:18 -0700
Organization: University of Southern California, USA
Distribution: usa
	<RSLAU.92Apr15002950@tarazed.usc.edu>
	<15APR199211114813@lims01.lerc.nasa.gov>
NNTP-Posting-Host: tarazed.usc.edu
In-reply-to: yystg@lims01.lerc.nasa.gov's message of 15 Apr 1992 11:11 EST  

In article <15APR199211114813@lims01.lerc.nasa.gov> yystg@lims01.lerc.nasa.gov (STEVE GRAHAM) writes:

   I don't know whether or not this was a flame.  Can't tell.  I'll assume it 
   wasn't. (graciously)

nope, not a flame.

   But seriously, I'm talking about a variable response curve to match the 
   ears response at variable volume levels.  How possible is it to do this 
   cheaply?  Seems like if you could build one yourself you could get some 
   extra points in an IASCA competition.  I know that this is somewhat like a 
   loudness switch, but what I'm thinking about would definitely be a neat 
   improvement, IMO.

I don't think I'll build an sbc yet, but a great development platform
would be a NeXT box driving a color LCD display.  Now that would win
points. Fully and easily programmable too.  Anybody want to send me
money so I can buy a NeXT box???  Better yet, anybody at NeXT reading
this, maybe you could find an unused NeXTStation that you could donate

;^)

-- 
Robert Lau - Systems Programmer, Unix Systems     213-740-2866
--  University Computing Services                 Internet: rslau@usc.edu
--  University of Southern California             Bitnet:   rslau@uscvm
--  1020 W Jefferson, LA, CA  USA, 90089-0251     UUCP:     ...!uunet!usc!rslau
From: william@pvcs.pvamu.edu (Devine, William Charles)
Newsgroups: rec.audio.car
Subject: a/d/s pq8 Center channel woes...
Keywords: ads center channel bridge
Date: 11 Apr 92 01:45:00 GMT
Organization: Texas A&M University, Academic Computing Services
News-Software: VAX/VMS VNEWS 1.41


   Hi....I have an a/d/s pq8 four channel amplifier and i am trying 
         to figure out a way to use my pre-existing center channel
         i had connected to the punch 45 this amp is replacing.
         I don't have a manual for this amp as i bought it from 
         someone second hand.  I was wondering if anyone knew a way
         to connect the center channel speakers to this amps left and
         right front channels to achieve a mono signal...I really liked
         the sound from my center channel (ads 320i plate) and would
         like to continue using it.. 
   If anyone has any suggestions or recommendations please reply...
   thanx
          (Frank, you out there?) see ya soon
                                           Whiz Kid
----------------------------------------------------------------------
william@pvcs.pvamu.edu      -----------         devine@riphys.rice.edu
----------------------------------------------------------------------

Newsgroups: rec.audio.car
From: yystg@lims01.lerc.nasa.gov (STEVE GRAHAM)
Subject: Re: Damping Factor in amplifiers.
News-Software: VAX/VMS VNEWS 1.41    
Organization: NASA Lewis Research Center
Date: 17 Apr 1992 09:45 EST  

In article <27146106@tronix.SignalPath.on.ca>, louis@tronix.SignalPath.on.ca (Louis Bertrand) writes...
(stuff deleted)

>In other words, amazingly high damping factors quoted in the spec. 
>sheets are meaningless taken out of context.  Much better to look
>at the power specs quoted at 2 and 1 ohm loads.
>Ideally power doubles as the load halves, and THD+N stays about
>the same -- I saw R-F Punch150 specs that quoted 2 ohm power with
>10% THD!
> 
>As usual, let your ears judge the results -- that's what it's all about!
> -- Louis
>--

Not trying to be difficult, but ...

The punch 150 HD I had quoted the following specs:
Into 4 ohms - 75 x 2 w some small THD.  With 10 % THD into _4 ohms_ it 
produces 120 x 2, which is downright impressive for a 75 x 2 amp.
Into two ohms, I don't know what the THD is, but mine came with that famous 
R.F. individual spec sheet (test of the amp you bought) and mine was speced 
out at 155.1 watts x 2 into 2 ohms.

BTW, in the manual, it says the amp only produces 90 x 2 into 2 ohms :-)

As much as I dislike R.F., the power they deliver is incredible.  There are 
better amps, but for a 2 ohm stable amp, the R.F. doubles, which is all one 
can really ask :-)

S. Graham
Newsgroups: rec.audio.car
From: biancol@bullet.ecf.toronto.edu (BIANCOLIN  FABIO S)
Subject: Re: enclosure questions
Summary: How come Perfect Box is Different? 
Organization: University of Toronto, Engineering Computing Facility
Date: Tue, 14 Apr 1992 00:01:52 GMT

In article <1992Apr8.005343.6421@ge-dab.GE.COM> harner@test1.dab.ge.com (Keith Harner) writes:
>
>The optimum internal volume for a ported enclosure is given by:
>
>  Vb = 15 * Qts ^ 2.87 * Vas
>
  Hi Keith, 
     Not that i doubt that this equation is correct, however.
  
  I used perfect box with all my parameters (Qes, Qms, Qts, etc) and
it told me that i needed 5.4 ft^3 for optimal ported enclosure (for one driver)
  
  Now, not that i doubt you know what you are doing, but why such a large
difference?   BTW, what exactly does optimum mean?  best response?  
  Gives lowest 3db point?
  
   Thanks in advance,
  Fabio


Newsgroups: rec.audio.car
From: Peter A. Cohen <peterco@eff.org>
Subject: Any Systems that Dampen Road Noise?
Organization: ON Technology, Inc.
X-Useragent: Nuntius v1.1a2
Date: Fri, 20 Mar 1992 17:27:12 GMT

I've seen a bunch of systems for home and office that use white noise
generators as a means of blocking ambient sound.  Or, more appropriately,
convincing people's aural centers that ambient sound is blocked.  Does
anyone know if such a system exists for autos, to reduce road noise? 
Admittedly, a more complex solution than installing better insulation...

- Peter
From: gt9605a@prism.gatech.EDU (Arlo James Aude)
Newsgroups: rec.audio.car
Subject: Re: Help on Isobarics??
Date: 10 Apr 92 06:55:07 GMT
Organization: Georgia Institute of Technology

dear subscriber,
  Isobaric classically means constant pressure.
  So, in terms of two compounded speaker drivers, it means that the pressure
between them is kept constant.  Under these conditions, the two drivers
act as one where the theill small parameter of VAS is cut in half because
the physicl resistance to motion of the mechanical units is half as much, 
I'm sorry, twice as much, as if run in series.  Also, because you have
two voice coils for the new drive unit(most likely run in parallel) the
resistance(and or impedance) is halved.  When this happens, the driver
loses 3db of efficiency because of the change in VAS, which means that
you can run the speaker in half the enclosure size, but you lose 3db
of efficiency so you have to double the power to make up for it.

-- 
Arlo James Aude
Georgia Institute of Technology, Atlanta Georgia, 30332
uucp:	  ...!{decvax,hplabs,ncar,purdue,rutgers}!gatech!prism!gt9605a
Internet: gt9605a@prism.gatech.edu
Newsgroups: rec.audio.car
From: jreiser@scott.skidmore.edu (jason reiser)
Subject: Re: car upgrade help needed
Organization: Skidmore College, Saratoga Springs NY
Date: Wed, 15 Apr 1992 02:59:22 GMT

This can be done without too many hastles:
	Acquire a Sony XA-7 or XA-7A (from a car stereo dealer).  This
unit is an RF modulator.  It plugs into your radio's antenna jack, and
the antenna gets pluged into it.  The RF modulator has 3 wires... one
is +12 volt, one ground and one is a trigger wire.  Whenever there is
+12 volts going into the trigger wire, the modulator will be on.  It
has a pair of RCA inputs which you can attach to the walkman with an
adaptor.  You'll need to buy a switch to control power to the XA-7(A)
and whenever it is on, one radio station will be replaced be the
signal from your walkman.  I have a feeling that I might be confusing
you, but if you have any questions about how this is accomplished,
please feel free to contact me.

				- Jason Reiser

Sony RF modulators sell for about $40 - $60
 
 
  /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
  \                                                            /
  / Jason Reiser  Skidmore College, Saratoga Springs, NY 12866 \
  \            E-Mail at jreiser@scott.skidmore.edu            /
  /                    Or Call 518-581-7079                    \
  \                                                            /
   \/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/
                                                                
Newsgroups: rec.audio.car
From: yystg@lims01.lerc.nasa.gov (STEVE GRAHAM)
Subject: Re: VOLTAGE CONVERTER
News-Software: VAX/VMS VNEWS 1.41    
Organization: NASA Lewis Research Center
Date: 15 Apr 1992 11:02 EST  

In article <703310956.189.0@backwater.bh.andrew.cmu.edu>, "Robert W. Igo" <ri09+@andrew.cmu.edu> writes...
>A resistor?  E = I * R, right?  Doesn't that mean that a resistor will only
>change the current?  Isn't that why they build transformers to convert voltage?
> 
>(Please, this is not a flame, Mitch.  I'm not sure myself, or else I wouldn't
>be asking.)

(stuff deleted)

In series, if the resistance of the two resistors is equal, they will both 
get half the voltage.  In parallel, the voltage will be the voltage of the 
power supply for both resistors, assuming that the power supply can handle 
the parallel load.  There are separate sets of equations for series and 
parallel.  Check out a physics book at the library for the formulas :-)

S. Graham
Newsgroups: rec.audio.car
From: tjd28@cas.org (;A/3G)
Subject: Powering an MTX Box...
Organization: None
Distribution: na
Date: Mon, 6 Apr 1992 12:04:28 GMT

I just bought an MTX box.  It's got dual 15's, 2 mids and 2 tweeters.  It
is rated for 250 watts per side.  I've hooked it up to a 100 wpc amp
and it sounded awsome but when I install it in my car I want to give it
all 250 watts.  So, does anyone have any suggestions on an amp.
Also, I'm new to this car audio business, so if there is anything
that I should know about connecting an amp, I'd be more than happy
to hear it.

Thanks alot,
	      Trav
	      tjd28@cas.org
From: mjensen@ub.d.umn.edu (marc jensen)
Newsgroups: rec.audio.car
Subject: Re: DSP for automatic Volume Control
Date: 16 Apr 92 04:10:06 GMT
Distribution: usa
Organization: University of Minnesota, Duluth. Information Services.

>>> Does anyone manufacture a car stereo with a DSP that automatically
>>> changes the volume of the music depending on the noise inside the car.
>>> You install a microphone near the headrest and the system plays music
>>> through the speakers to adjust focus.

Well, it's not a DSP unit, but Alpine put out a new deck, the 7525, which is a
removable faceplate design cassette/CD changer head unit.  It has a function
called Ambient Sound Compensator, which (a quote from the brochure) "helps
maintain a comfortable listening environment by automatically adjusting
volume and tone.  Three sensors feed data into a computer chip, which
continually adjusts system volume and frequency response to compensate for
the effects of road noise."  I haven't seen one, but now that you know one is
out there, you can go look for yourself.

							Marc
Newsgroups: rec.audio.car
From: bladex@engin.umich.edu (Robert Klingsten)
Subject: Re: who makes what in the car audio world...
Date: Fri, 10 Apr 92 14:09:11 EDT
Organization: University of Michigan Engineering, Ann Arbor

Add "Crutchfield amps" to the list.  Those are also made by Precision
Power (I confirmed my suspicions with PPI).  They told me that although
they make the Crutchfield amps, the PPI amps are made "better"! Hmmm....