HDTenEightyP/NetNews huggingface dataset:
From: rslau@usc.edu (Robert Lau)
Newsgroups: rec.audio.car
Subject: Re: Damping Factor in amplifiers.
Date: 15 Apr 1992 00:42:36 -0700
Organization: University of Southern California, USA
NNTP-Posting-Host: tarazed.usc.edu
In-reply-to: biancol@bullet.ecf.toronto.edu's message of Tue, 14 Apr 1992 20:12:14 GMT

In article <1992Apr14.201214.7702@helios.physics.utoronto.ca> biancol@bullet.ecf.toronto.edu (BIANCOLIN  FABIO S) writes:

      Well, i understand that the lower the damping factor, the more
   difficult it is for the amplifier to stop the cone of the speaker from
   moving, and at higher volumes, this will cause distortion.

Exactly.

     But what is a good number for Damping Factor?  Some HiFonics
   amps i have read about range from 150 for a 35w/chan to 500 for 
   a 600w/chan (note: i assume this is in 4 ohm mode).

I hate math.  I'm sure others here can give you equations to show what a
minimum accepted damping factor should be.  All I can say is...  buy
what you can afford!  I would say that around 500 was an impressive
number a year or two ago.  Nowadays, Phoenix Gold amps have damping
factors well over 1000.  But they're priced accordingly too.

      The Blade amps i mentioned in the previous article have a 
   DF of "> 100"  (note: once again i assume in 4 ohms)

This is low.

     So whats right?  Whats a good number?  How do you determine
   Whether or not its worth it to load down an amp to 2 ohms?

It really depends on what type of music you listen to, how loud you want
to listen to it and how much you're willing to spend, you might not be
able to afford another amp just to drive another sub.  Running at 2 ohms
might be a good compromise if you don't intend to crank it.

    Is the solution to buy a bigger amp and run every channel into
   4 ohms?

Yes, that's what I've done.  Everything runs cooler as well.  Distortion
ratings are also lower at max rated power into 4 ohms than at max rated
power into 2 ohms.

-- 
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: louis@tronix.SignalPath.on.ca (Louis Bertrand)
Subject: Re: Damping Factor in amplifiers.
Newsgroups: rec.audio.car
Date: 16 Apr 92 03:33:05 GMT
Distribution: world
Organization: Signal Path Designs

biancol@bullet.ecf.toronto.edu (BIANCOLIN  FABIO S) writes:
>    Well, i understand that the lower the damping factor, the more
> difficult it is for the amplifier to stop the cone of the speaker from
> moving, and at higher volumes, this will cause distortion.
[deletions...]
> Whether or not its worth it to load down an amp to 2 ohms?
>  Is the solution to buy a bigger amp and run every channel into
> 4 ohms?    

Damping factor is a ratio of amplifier output impedance  
(including wires) to load impedance.  For car audio, the 
standard reference load impedance is 4 ohms, assumed 
purely resistive (Ha!).

Ways of improving (lowering) amplifier output impedance include
paralleling more output transistors or increasing the feedback.
Lots of feedback adds to amplifier instability and transient
inter-modulation distortion (TIMD).

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
--
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)
Xref: sparky rec.audio.car:1939 rec.autos:10930 misc.consumers:10198
From: carl@Cayman.COM (Carl Heinzl)
Newsgroups: rec.audio.car,rec.autos,misc.consumers
Subject: Re: Honda factory radio comments? Problems?
Date: 8 Apr 92 12:00:04 GMT
	<1992Apr4.210718.2226@investor.pgh.pa.us>
Followup-To: rec.audio.car
Organization: Cayman Systems Inc., Cambridge, MA
In-reply-to: rbp@investor.pgh.pa.us's message of 4 Apr 92 21:07:18 GMT
bcc: carl


Bob (and others)

>>I have noticed that the reception is sometimes not very good
>>with the radio. 
>>And that the frequency response of the music (from the radio)
>>is also not very good.
>>BUT - the tape player sounds excellent.  There is a noticeable

>I have a 1992 Prelude and my daughter has a 1992 Accord.  There are no
>discernable problems with the radio in either.  The fact you only have
>the problem sometimes suggests you may be trying to listen to stations
>that are too far away.  In most radio designs there is a trade-off
>between fidelity and sensitivity.  The tuners with the best sound often
>don't have the best range.  I haven't used my tape player but I find FM
>does not measure up to the sound available from LPs and better CDs.  It
>ought to be competitive with all but the best tapes.  AM is another
>story.

>BTW, a lot depends on what you are used to.  I have a very good stereo
>system at home and no car radio I have ever heard can match it.
>Nevertheless, the Honda radios do a reasonable job.

A LOT also has to do with the terrain you're driving on.  In
Pittsburgh, the hills and valleys often make reception less than ideal
with their multiplie reflections.  I remember that we would get
"ghost" images on our TV a LOT on some of the more distant stations
when I lived there.  There were the two or three "main" stations that
we could always get excellent reception on and others literally
depended on the weather (Altoona, one in Ohio, etc).  Of course, we
were only using rabbit ears (about equivalent in length to a car
stereo radio).

Here in the Boston area, we can usually get one of the local FM
stations on our car stereo at LEAST 30 miles away and usually farther,
but compared to PA this area is a plain state (except for the taxes
:^) ).

-Carl-

--
From: kirk@hpcc01.corp.hp.com (Kirk Lindstrom)
Date: Sun, 12 Apr 1992 05:59:54 GMT
Subject: Re: Install in Ford Ranger
Organization: Shredding the water of SF Bay, HP-OCD
Newsgroups: rec.audio.car

>	I have a friend who is building a system in an 85 Ranger.  He
>now has 6x9's in the lower door, 4" in dash and 8" subs behind the seats.
>Each set of speakers has its own amp.  Does anyone have any suggestions or
>cool ideas on how to imporve the mid bass to high end sound quality.  The
                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The most important things for good sound are source and speakers.  If he
doesn't have CD that DOES NOT use fm modulation, get it.  Then upgrade
the speakers.  The best 6x9s I've heard are Boston Accoustics.  

>present drivers are of above average quality.  Has anyone any experience
>with dash modifications (eg replace 4" with 4x6's), installation of
>drivers in the vents or 6 1/2" mid bass in the doors.  He also has

For sound quality, it is hard to beat MB Quart seperates.  They are nearly
twice the price of the BA 6x9s. but worth it if you like quality sound.

>a set of Recaro seats instead of the bench seat.
>
>Jeff Smith
----------

-Kirk out
Newsgroups: rec.audio.car
From: D1SAR@AKRONVM.UAKRON.EDU (Steve Rimar)
Subject: Reliability of Equiptment
Organization: The University of Akron
Date: Wed, 15 Apr 1992 13:02:34 GMT

Has anyone seen or know of a listing that rates auto audio equipment by
reliability.  I would hate to purchase stuff that has a poor repair record.
We could take a survey from readers ?  I haven't seen a Consumers Report
magazine that lists the reliability of Auto Audio.
 
Steve Rimar
The University of Akron
Akron, Ohio
D1SAR@VM1.CC.UAKRON.EDU
Organization: Sophomore, Math/Computer Science, Carnegie Mellon, Pittsburgh, PA
Newsgroups: rec.audio.car
Date: Thu, 9 Apr 1992 21:38:56 -0400 
From: "Robert W. Igo" <ri09+@andrew.cmu.edu>
Subject: power antennae

Hi again.  My car radio doesn't tend to pick up lots of stations very well
(I should clarify that I live in hilly areas-- Pittsburgh) and I wondered
about getting a power antenna to replace the one currently on my car
(82 Honda Accord).  Any suggestions?

--Bob
Newsgroups: rec.audio.car
From: daw@jhunix.hcf.jhu.edu (Dave Webb)
Subject: Car Audio For Sale... UPDATE!
Organization: HAC - Johns Hopkins University, Baltimore
Distribution: na
Date: Wed, 8 Apr 1992 14:17:33 GMT

I have the following items for sale:

Software:
Wealthbuilder version 1.11 -
	5.25" Disks
	OrMint Condition - original box and documentation
	PRICE: $75.00 or best offer

IBM DOS 4.0 -
	3.5" Disks
	NEW - NEVER USED! Original box and documentation
	PRICE: $25.00 or best offer
	* OFFER PENDING *

Car Audio:
Pyle Driver 6940 6x9's -
	200 watts/channel
	50-22,000 Hz. Frequency Response
	40 oz. Magnet for MEGA BASS
	Less than 6 months old - still under warranty
	PRICE: $125.00
	* SOLD * 

LA Sound Subwoofers (LA 12 AS) 12" pair -
	200 watts/channel
	24-1,500 Hz. Frequency Response
	BRAND NEW - NEVER USED! Original box and dox
	PRICE: $150.00
	* OFFER PENDING *
Jensen JXL692 6x9
	160 watts/channel
	40-25,000 Hz. Frequency Response
	BRAND NEW - NEVER USED! Original box and dox
	PRICE: $75.00
	* OFFER PENDING *
If you are interested or have questions, please leave me some mail.
		
		Thanx,
			Dave Webb
P.S.  For those of you who left me messages of interest.. PLEASE get back 
with me and let me know something one way or the other..
From: sharif@ee.fit.edu (Shahid Muhammad Sharif)
Newsgroups: rec.audio.car
Subject: Speaker Connections
Summary: Does it matter if you connect the +ve lead from the amp to the -ve inpu
Keywords: Polarity
Date: 15 Apr 92 00:49:47 GMT
Organization: Florida Tech, CP/EE Dept.

Does it matter if the speakers are connected with opposite polarity of the 
speakers.  If it does how can I find out which lead is +ve and which one is
-ve, because when I connected the system in my car I used the same colored
cables for speaker connections.

MY E-MAIL ADDRESS IS: sharif@ee.fit.edu
     














       
Newsgroups: rec.audio.car
From: tjd28@cas.org (;A/3G)
Subject: MTX and Coustic 460
Organization: The "Going Deaf" Society...
Distribution: na
Date: Tue, 14 Apr 1992 12:34:04 GMT


Thanks to those who helped me with the questions about amps about a week
ago.  I hooked up a Coustic 460, 98wpc, to my MTX box, dual 15's, and the
thing THUMPS, HARD!!!  Cranked a little Magic Mike the other day, just to
see exactly how much thump this thing had, and it rocked.  Damn near knocked
the wind out of me a couple times.  But, anyway, I read alot about people
having heat problems with there amps, well, we jammed my system for well
over an hour yesterday, with a lot of hard hitting bass, and the amp never
even got warm.  I couldn't believe it.  A buddy of mine runs two Pyle 15's
and two 90 db horns with a 100 watt Concord, and that thing is HOT inside
of 10-15 minutes.  But, anyway my question, I had to use the back
speaker wires to hook up the system, and I'm getting a little motor noise
but, it can only be heard when there is no music, (i.e while changing cassettes)
and I was wondering if a Noise Suppressor would get rid of it. Any other ideas?

Thanks in advance,
		   Trav
		   "Thumper: owner of the little Talon that goes Boom!"
Newsgroups: rec.audio.car
From: gregh@gpu.utcs.utoronto.ca (G. Hurtault)
Subject: Why isn't there a FAQ???
Organization: UTCS Public Access
Date: Fri, 17 Apr 1992 17:59:26 GMT

 Since there are so many people ho seem to have good knowledge of
 what's going on in this newsgroup, why isn't there some sort of
 FAQ? I think that it would save us alot of bandwidth in the long
 run, plus it ould be easier for those of us who don't have all the
 questions. I realize that it would be a faily large undertaking but
 I think it would be worth it (sorry but I'm one of those who don't
 have a clue when it comes to car audio).

 All of you car audio wizards should think about pooling your brains
 together for the betterment of this newsgroup.

 Thank you...I'm done now.

 Greg.


-- 
      -----    |                   Greg Hurtault
     /     \   |            gregh@gpu.utcs.utoronto.ca
     | reg___  |                 
     \______/  |  Is that a wiggle or a struggle?" "Macho King" Randy Savage 
Organization: Junior, Electrical and Computer Engineering, Carnegie Mellon, Pittsburgh, PA
Newsgroups: rec.audio.car
Date: Fri, 10 Apr 1992 18:51:39 -0400 
From: Amit Likhyani <al1x+@andrew.cmu.edu>
Subject: Re: power antennae

My experience has been that power antannae do not improve reception. 
You may want to get other opinions, but power antennae basically are
just a convenience.  I you want to get one, call Crutchfield or JC
Whitney everything automotive.

Mit
From: rslau@usc.edu (Robert Lau)
Newsgroups: rec.audio.car
Subject: Re: 6s & 8s
Date: 14 Apr 1992 23:31:45 -0700
Organization: University of Southern California, USA
Distribution: rec
NNTP-Posting-Host: tarazed.usc.edu
In-reply-to: "mike frisch"'s message of 12 Apr 92 01:00:41 EST

In article <199212.1547.4846@dosgate> "mike frisch" <mike.frisch@canrem.com> writes:

	Can somebody recommend a good subwoofer (ie. able to reproduce the
   lower frequencies) in these smaller sizes?  A recent car audio magazine
   mentions it being difficult to find such a thing.  Is this true?

Yes, it's true, you're limited by plain & simple physics.  To get satisfying
bass, you've got to move lots of air quickly.  Unfortunately, 6" woofers
generally can't do this.  What you can look for is a long excursion 6"
and/or a well designed box.  But even with a good box, there's the trade-off
between frequency range and sensitivity...

	Much thanks for your help in advance.  I do not need a booming
   system, but rather want some low frequency reproduction without taking
   up an enormous amount of space for 10"s or 12"s.

I've got an a/d/s/ 6.2 in each front door, basically 2 6" (mid-)woofers
bolted to the same mounting plate.  Currently, they're running in a sealed
enclosure that replaced the lower half of the door and is of the correct
volume.  Enough mid-bass punch to satisfy me, no booming here either.
50watts to each 6".

-- 
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: gt0869a@prism.gatech.EDU (WATERS,CLYDE GORDON)
Newsgroups: rec.audio.car
Subject: Re: Autotek Amplifiers? (1 ohm stability stuff)
Date: 17 Apr 92 15:46:51 GMT
Distribution: na
Organization: Georgia Institute of Technology

In article <scp69INNk7q@lisa.cs.widener.edu> poulson@cs.widener.edu (Joshua R. Poulson) writes:
>1x400 into 1 ohm  -->  50 

Still better than a Punch 150 into 4 ohms! Isn't that sad :-)?

(note: Yes, I do have a big anti-Fosgate bent, but it is based
on years of observations. So, I do believe I have a viable basis,
given the # I have used and fixed )

I have used the 225HCCA into 1 ohm mono, and frankly, the bass did
seem to get a little muddy. I think the problem was a combination
of reduced damping factor and that the amp simply was running out
of supply current. IMHO, none of the high-current amps out there
have big enough supply caps. Remember, stored energy is the product
of voltage and capacitance; reducing the voltage (as is the common
way of producing high-current amps) results in less energy storage
for the same size cap. Therefore, much larger (usually a factor of
4) caps for the same TOTAL power output are needed! No one I have
"reverse engineered" does this. The Orion 250 HCCA is the closest,
and it does seem to have the best bass of any high current amp IMHO.
Next time I get hold of a 225, methinks I will try a cap size upgrade...

Regards,
Gordon.
 

-- 
WATERS,CLYDE GORDON-Georgia Institute of Technology Atlanta Ga 30332 
******<LANGUAGE IS A VIRUS! - Laurie Anderson-Home of the Brave>******* 
uucp:	  ...!{decvax,hplabs,ncar,purdue,rutgers}!gatech!prism!gt0869a
Internet: gt0869a@prism.gatech.edu
From: louis@tronix.SignalPath.on.ca (Louis Bertrand)
Subject: Re: DSP for automatic Volume Control
Newsgroups: rec.audio.car
Date: 16 Apr 92 02:59:59 GMT
Distribution: usa
Organization: Signal Path Designs

yystg@lims01.lerc.nasa.gov (STEVE GRAHAM) writes:
> Another interesting gadget - a dsp to shape the response curve to match the 
> ears response at given volumes - i.e. an extended "loudness control".  This 
> would allow you to adjust the volume to any level and not have to raise/
> lower bass when you turn the volume up/down.  I think I would pay some $$ 
> if such a beast were made.
> 
It would be fun to experiment with, but I don't know that it would
be well received by a wide audience.

The problem is that this gizmo would have to deal with the 
psycho-acoustic effects of hearing.  The response changes with
absolute volume (Fletcher-Munson curves, etc).  It is also
susceptible to "masking" -- a strong signal at a given frequency
will mask softer ones at adjacent frequencies.  Finally,
a given frequency is perceived as a different pitch depending
on the volume.
So the shape of the absolute response is a very dynamic thing 
and trying to track it could very well make things worse.

A, B, C, and D weighting curves are pegged to particular 
listening levels and a simple algorithm so smoothly transition
from one to the other would be worth playing with, but
listener preferences would make the gizmo really chancey.
(Then again, there's a lot of Epicentres out there...)

Ciao!
 -- 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)
Newsgroups: rec.audio.car
From: klm41661@uxa.cso.uiuc.edu (Kevin L. Molander)
Subject: For Sale: MTX 10" dual coil
Organization: University of Illinois at Urbana
Date: Tue, 14 Apr 1992 22:17:04 GMT

I have for sale one 10" MTX subwoofer.
It has dual voice coils each of which can handle 135 watts max power.
It is poly, with foam surrounds.
Its about six months old, and we are upgrading to 12".
I paid $59 (bought it at Crutchfield),
and I'm asking $35.
I also have a grill that will fit it, I paid $12 for it.

reply to:  Kevin Molander
klm41661@uxa.cso.uiuc.edu    or    free2278@vmd.cso.uiuc.edu
From: rslau@usc.edu (Robert Lau)
Newsgroups: rec.audio.car
Subject: Re: active noise canceling (was: DSP for automatic Volume Control)
Date: 15 Apr 1992 12:12:07 -0700
Organization: University of Southern California, USA
	<1992Apr15.164613.29648@sequent.com>
NNTP-Posting-Host: tarazed.usc.edu
In-reply-to: news@sequent.com's message of Wed, 15 Apr 92 16:46:13 GMT

In article <1992Apr15.164613.29648@sequent.com> news@sequent.com (News on Muncher) writes:

   A year or two ago I read about a system installed in Lotus vehicles that
   uses microphones and the car's speakers to listen to and cancel noise by
   producing a trough for every peak, and vice versa.  This is calculated
   in real time, so it has to use fast signal processing.  Of course it can
   add music on top of the noise-canceling signal.  Has anyone heard about
   this technology lately?

Last I checked, BMW, Toyota and Nissan were close to market on this.  In fact
they should debut in their 93 models.

Porsche had a the reverse, an external speaker cancelling the exhaust.  Don't
know if this will ever make it out...  Brings back memories of Get Smart's
Shoosh Copter or Blue Thunder's silent mode

;^)

-- 
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
Newsgroups: rec.audio.car
From: tjd28@cas.org (;A/3G)
Subject: MTX Stickers...
Organization: None
Distribution: na
Date: Mon, 6 Apr 1992 11:54:04 GMT

Does anybody know if MTX makes window stickers and where I could
find them.  I've been to a few car shows (most recently the one
at the Huntington Civic Center) and still have yet to see any.

Thanks alot,
	      TRAV
Newsgroups: rec.audio.car
From: edwin@csri.toronto.edu (Edwin Allum)
Subject: JL Audio driver specs
Keywords: speakers
Date: 13 Apr 92 21:59:24 GMT


I need the driver specs for the following JL audio models:
8W2, 8W3, 10W1, 10W2, and 10W5.

If someone out there knows it, can you please send it to me.

I'm interested in using it in a single reflex bandpass enclosure.
Any info on this kind of enclosure is also appreciated.

Thanks, Edwin.
----
Edwin Allum
CSRI, University of Toronto
Internet: edwin@csri.toronto.edu
Phone: 416-978-8715
Fax: 416-978-4765
From: louis@tronix.SignalPath.on.ca (Louis Bertrand)
Subject: Re: Amp schematic request
Newsgroups: rec.audio.car
Date: 5 Apr 92 19:26:42 GMT
Distribution: world
Organization: Signal Path Designs

frank@owlnet.rice.edu (Franklin Tae-Sung Kang) writes:
> In article <53453@hydra.gatech.EDU> ccastbs@prism.gatech.EDU (Shannon Bell) writes:
> >I was wondering if anyone had a set of schematics for an apmlifier, suitable
> >for a car, that they could send me? I can deal with about any format of 
> 
> 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...

> Also, I think last year Radio Electronics had an article on
> a car amp a little more modest (50wpc?).
> 
Can you dig up the exact reference?

I'm also looking into getting back issues of the Audio
Amateur dealing with the RKV amplifier project.  I remember
it started quite a letter-to-the-editor war about DC-DC 
converter supply design (sorta like a flame war...).
Anybody have some photocopies of it? (circa 1988?)

Have fun!
 --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)
Newsgroups: rec.audio.car,rec.autos,misc.consumers