From: bell@hops.larc.nasa.gov (John Bell)
Newsgroups: rec.audio.car
Subject: Re: subwoofers/boxes
Date: 31 Dec 1992 11:41:43 GMT
Organization: NASA Langley Research Center
NNTP-Posting-Host: hops.larc.nasa.gov

In article <1992Dec30.035321.2866@schbbs.mot.com> bstdenis@mailbox.fwrdc.rtsg.mot.com (Brian St. Denis) writes:
(...)
>>>My question is can the difference in woofers make such a huge difference?
>>
>>You didn't mention the dimensions of the port in your box, so I 
>>can only assume you built it according to MTX specs. A few weeks ago, there
>
>The port is 7.1" long, 4" diameter like the spec says.
OK, sounds good so far.
> 
>>was a nice article posted describing how to tune the port after you have
>>built the box. Although you have some leeway in box volume, there is very
>>little leeway in the dimensions of the port, so the tuning process can be
>>very important and can make a significant difference.
>>
>
>I missed that post some how.  If someone has the article on tuning boxes,
>pleaes e-mail it to me.  Thanks in advance.
>
I'll send it to you.
>
>>As far as the differences between drivers, you DO generally get what you pay
>>for. Designing a good driver is an extremely complex compromise between
>
>I went to a place here that primarily sold Rockford/Fosgate stuff.  They had
>one listening room and many trophies around the entry room.  I told their
>manager my dilema and he (a R/F dealer) said that there isn't that much
>difference in the woofers and the the large companies like MTX, R/F, etc.
>generally don't make sutff that "doesn't sound good."  Just his opinion.
>He also does NOT use the Punch Pro series woofers in the competition cars
>because they take too much power; he uses their middle line.

This is an interesting point. Do you buy only top-of-the-line for competition
or do you put more emphasis on good installation techniquesx? If he has
trophies, he must know what he's doing, right? On the other hand, the MTX
woofer he sold you doesn't sound good. If you built the box right, I'd say
that he just sold you something that "sounds bad". I will concede that an
improperly installed top-of-the-line woofer sounds just as bad as the most
el cheapo Radio Sh**t drivers, but there is a big difference if they are in a
properly designed enclosure. Unfortunately, you can't tell the difference until
you've bought the driver and built the box, unless you know how to interpret
the specs. Even then manufacturers lie, so you have to measure it yourself.
SO....you end up trusting the dealer, which is not bad if he knows what he's
doing.
  So far as the pro series and power handling, that's a decision driven by
the class he wants to compete in (by the way, were his trophies only for local
competitions, or for non-professional entries? Just wondering). It's generally
easier to win (but not always, no flames please) in the lower power classes.
On the other hand, speakers with higher power handling can produce much
better (not necessarily louder) sound if they are given enough power.
>
>>competing design goals, and it takes money to figure out the best way to get
>>what you want. I don't know the specs for the two drivers you mentioned, but
>>if the Petra has higher power handling capacity, I certainly would expect it
>>to sound better (all other thing being equal) if you have enough power.
>>
>
>I think both my MTX and the Petrus handle 200w peak.
>
>This same dealer said that I should go with an infinite baffle (sp?) 
>instead of a box.  I have a Mustang notchback with a trunk.  He says
>that would be better than having a good vented box of 2 cu. ft. or so.
>How does an infinite baffle set up sound compared to a good box set up?
>The price he said is $150 for the installation of the infinite baffle.
>I can make a 2 cu. ft. box for $15 and a few hours of labor.  Also, a
>box could be moved to a different car.
>
Hmmm, if MTX recommends a ported enclosure, why does he think an infinite
baffle (also called sealed) enclosure will sound better? Does he have software
to model it with? How much better will it sound? I'd want to know before
forking over the bucks.

>All I know for sure is that what my buddy has with his Petrus is WAY better
>than what I have with my MTX and we spent the same give or take $40.
>
>-Brian
>"We like the cars, the cars that go ..."

If you're still with me, I think that if you like the Petras, return the MTX
drivers and duplicate your buddy's setup. I don't know what your time is worth
to you, but for $40 difference, it just doesn't seem worth it to go to a lot
of trouble to make the MTX's sound better.


-----
John Bell
NASA Langley Research Center
bell@hops.larc.nasa.gov