Novice Question: Stereo Woofers in One Box - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way

Multi-Way Conventional loudspeakers with crossovers

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 19th December 2007, 08:29 PM   #1
diyAudio Member
 
Join Date: Apr 2004
Location: NYCNY
Default Novice Question: Stereo Woofers in One Box

Hi,

I am designing a boombox for ipods and the like. It will be a single box, roughly the size of a large 80's ghetto blaster. Two woofers and two tweeters, powered by a 12W T.I. evaluation board.

I'm using Unibox and other FRD spreadsheets to do the math, but one question is puzzling me.

Unibox has options for a single drive unit or 2 drive units in series or parallel. But what happens when two woofers are sharing the same volume, but each driver is connected to a separate amp channel (i.e. stereo)?

Can I just use single unit setting? Should I use the series/parallel setting and double/halve the impedance? I'm confused.

Yes, I know this is not the ideal set up, and most DIY'ers would divide the box into two separate volumes, but just humor me for a moment.

Thanks,
Josh
  Reply With Quote
Old 19th December 2007, 08:34 PM   #2
diyAudio Member
 
Saturnus's Avatar
 
Join Date: Jun 2005
Location: Copenhagen, Denmark
I wouldn't do it unless you're dead certain all your mp3s are encoded in joint stereo which basically makes the bass under 200 Hz mono. But would it be very difficult to have a center and bracing wall dividing the 2 chambers?

You run the risk of certain songs not playing bass, or very distorted bass because one channel doesn't play the same as the other channel. In which case both drivers "see" a different size box than they were designed to resulting a very degraded bass response.

  Reply With Quote
Old 19th December 2007, 10:49 PM   #3
diyAudio Member
 
Join Date: Apr 2004
Location: NYCNY
Thanks for the reply, Saturnus. By the way, your project is great. In fact, when my colleagues and I were first starting our project, I sent a link to the thread to them for inspiration.

That said, our project is more about aesthetics than audio fidelity (don't shoot me! ). It's actually more of an art project than anything else. We plan to make one or two prototypes and if they sell we'll make more.

We're going to have to have the box built from CNC-cut solid surface (like Corian). It's hard enough getting a fabricator to build us a simple box, let alone something with internal dividers.

So.... let's just say, for poops and giggles, that I HAVE to use a single box even though it's somewhat heretical. What figures should I plug into the simulators to get the best box size and crossover design, all things considered?

Thanks,
Josh
  Reply With Quote
Old 20th December 2007, 01:02 AM   #4
diyAudio Member
 
Join Date: Feb 2002
Location: Western Sydney
use the single driver setting but double the Vas
  Reply With Quote
Old 20th December 2007, 05:09 AM   #5
diyAudio Member
 
Join Date: Apr 2004
Location: NYCNY
Okay, will do. Thanks, Pete!

If anyone else has an alternative approach, feel free to chime in.

Josh
  Reply With Quote
Old 20th December 2007, 11:34 AM   #6
bjorno is offline bjorno  Sweden
diyAudio Member
 
Join Date: Mar 2005
Location: Jacobsmountain
Send a message via MSN to bjorno
joshkrahn:

Quote:
...an alternative approach...
Here is one Iíve built 20 years ago after reading 'Sound System Engineering, 2:nd edition by Don Davis &Carolyn Davis' book page 330 where a similar picture is shown. See the schematic picture 1(2).

Later I also included small Rs and Ls speakers delayed by a MITSUBISHI M65831AP/FP karaoke circuit + another PA: See picture 2(2).

The speaker drivers are obsolete by now, but of course, other suitable ones can be used instead.

Why not build a more powerful ghetto blaster using this concept?

My use of these Speakers where:

If hooked up and placed on or below a small TV set with the small Rs and Ls surround speakers, the wide stereo illusion was in my opinion quite impressive and improved compared to the ordinary built in TV drivers.

b

1(2)
Attached Images
File Type: gif besselstereo.gif (64.1 KB, 80 views)
  Reply With Quote
Old 20th December 2007, 11:35 AM   #7
bjorno is offline bjorno  Sweden
diyAudio Member
 
Join Date: Mar 2005
Location: Jacobsmountain
Send a message via MSN to bjorno
2(2)
Attached Images
File Type: gif karaoke delay.gif (21.0 KB, 66 views)
  Reply With Quote
Old 20th December 2007, 01:31 PM   #8
sreten is offline sreten  United Kingdom
diyAudio Member
 
Join Date: Nov 2003
Location: Brighton UK
Hi,

FWIW most recordings do not have out of phase bass because it
mostly cancels in room and wastes bass excursion. Occasionally
you do get bass in one channel and none in the other on older
stuff but this does not cause a serious problem.

There is not much advantage to seperating a boom-box.

The box should be designed for two drivers, series / paralllel does
not matter, but as stated doubling Vas does the same thing.

/sreten.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
DAC question from a novice fishwinker Digital Source 6 17th June 2006 07:41 AM
Novice question huguini Full Range 25 6th September 2005 02:00 AM
Novice Question (with plea for help) PAPAPOPEYE Everything Else 2 18th February 2005 06:44 AM
confused novice with zen question fezz Solid State 1 13th November 2002 07:52 PM


New To Site? Need Help?

All times are GMT. The time now is 06:05 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2