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 11th August 2008, 01:14 PM   #1
diyAudio Member
 
Join Date: Jan 2005
Location: Brighton
Default Coaxial 3-way passive floorstander - Seas H1333 and Dayton RS225S

The cost and complexity of my previous H1333 plus Linkwitz Transform XLS10 concept has got a bit overwhelming so I'm looking at a passive alternative with similar characteristics.

How viable does it sound to have a 7" coax crossing over passively with a 2nd order electrical filter to an 8" woofer at 200Hz? With the woofer in 40 litres tuned to 30Hz, F3 is 35Hz and it can handle full power from my 50W/ch amp without exceeding Xmax.

The passive low pass on the woofer looks easy to achieve but the impedance peak of the coax looks like it will need an LCR to get correct filter response.

This looks like it will achieve good coherence (important due to relatively close listening positioning), low distortion (due to minimal excursion from the coax) and strong clean bass output (high Xmax and low F3) but I'm sure there must be something I've overlooked!

Alex
  Reply With Quote
Old 11th August 2008, 02:40 PM   #2
sreten is offline sreten  United Kingdom
diyAudio Member
 
Join Date: Nov 2003
Location: Brighton UK
Hi,

For those two drivers most of the baffle step would need to be
built into the H1333 to work well, its an unusual choice for a
3-way, one could argue a 2.5 way would be more effective.

By overdamping the H1333 one can ensure the other driver
does more of the bass work and this would have a slightly
underdamped alignment so they add to what you want.

/sreten.
  Reply With Quote
Old 11th August 2008, 03:12 PM   #3
diyAudio Member
 
Join Date: Jan 2005
Location: Brighton
I'm intending to place these relatively near the back wall so will have very little baffle step correction if any. The reason for the 3-way design is to minimise excursion on the coax and thus reduce the effects caused by a moving waveguide on the tweeter, with the other benefit being lower distortion in the mids due to lower excursion.

Alex
  Reply With Quote
Old 11th August 2008, 04:04 PM   #4
diyAudio Member
 
Join Date: Jan 2005
Location: Chicago, IL
Send a message via AIM to Mark Seaton
Hi Alex,

A coax in a 3 way configuration works quite well.

The tricky part is implementing a passive crossover, particularly one which allows a low crossover frequency. While the production version of my Catalyst uses a much higher power coaxial, this prototype/beta unit worked very well within its limits (limited by the tweeter), and sounded quite good IMO.

The crossover design is a major factor, and while I went fully 3 way active in the final version, the one depicted uses a passive XO on the coax with and active crossover handling the bass to coax transition. Ideally you want to keep the crossover in the 150-300Hz range to minimize off axis variations. With physically smaller drivers you will have less issue with a crossover near the upper limit, as spacing can be tighter.

I also helped with the JTR pro speakers which use an 8" and 12" coax mated to pairs of same size woofers in vented boxes.

Again, the passive crossover below 300Hz can be tricky, and MUST be modeled with real impedance curves, and do keep and eye on the impedance minimums.

Click the image to open in full size.

Best of luck with the project.
__________________
Mark Seaton
  Reply With Quote
Old 11th August 2008, 04:18 PM   #5
diyAudio Member
 
Join Date: Jan 2005
Location: Brighton
Quote:
Originally posted by Mark Seaton
Again, the passive crossover below 300Hz can be tricky, and MUST be modeled with real impedance curves, and do keep and eye on the impedance minimums.
Is that with measured impedance curves or will simulated magnitude/phase curves from WinISD or similar be sufficient?

Alex
  Reply With Quote
Old 12th August 2008, 11:44 AM   #6
sreten is offline sreten  United Kingdom
diyAudio Member
 
Join Date: Nov 2003
Location: Brighton UK
Hi, See Zaphs blog for some H1333 measurements, /sreten.
  Reply With Quote
Old 13th August 2008, 12:43 PM   #7
diyAudio Member
 
Join Date: Jan 2005
Location: Brighton
Quote:
Originally posted by sreten
Hi, See Zaphs blog for some H1333 measurements, /sreten.
Thanks, very interesting! Look forward to his analysis of the results.

Alex
  Reply With Quote
Old 14th August 2008, 01:12 PM   #8
diyAudio Member
 
Join Date: Jan 2005
Location: Brighton
For the passive crossover @ 200Hz, should I be using an LCR on the woofer's impedance peak above the tuning frequency, another on the midrange's impedance peak, and then Zobels on both, and leaving the woofer's lower impedance peak uncorrected?

Alex
  Reply With Quote
Old 14th August 2008, 04:57 PM   #9
diyAudio Member
 
Join Date: Jan 2005
Location: Brighton
Just worked out the numbers using WinISD Pro for impedance plots and Elliott's info on passive crossover design. Zobels and LCRs as suggested in my previous post. Then putting those numbers into the Passive Crossover Designer spreadsheet generates a plot for the low/mid area that is flat within +/- 0.75dB.

Alex
  Reply With Quote
Old 14th August 2008, 07:39 PM   #10
diyAudio Member
 
Join Date: Jan 2005
Location: Brighton
Looking at the few crossover designs for the H1333 I'm thinking they're all unusable because I'll be using a larger baffle and close to wall positioning will little or no baffle step, and it looks like the BSC is totally integrated into these crossovers, including tweeter padding etc.

Confusingly the SEAS Loki crossover appears to be a 2nd order woofer with a 3rd order tweeter (with an additional paralled cap/resistor in series before the crossover presumably to add treble), which leaves me puzzled about the phase at the crossover point.

Is there anything notable I should consider in designed a crossover for a coax design?

Alex
  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
Dayton RS225S-8 Transmission Line BillH Multi-Way 9 12th September 2011 09:39 AM
FS: Dayton RS225s-8 and RS28A-4 force of 1/2 Swap Meet 11 13th December 2008 02:26 AM
Seas H1333 coax driver Q's weinstro Multi-Way 0 22nd May 2008 04:20 PM
FS: Dayton RS225S, AA Poly Mids, Vifa 10MD, KLH omarmipi Swap Meet 5 11th October 2007 06:07 PM
Seas' T17 and T18 coaxial loudspeakers SSassen Multi-Way 14 24th March 2005 04:34 PM


New To Site? Need Help?

All times are GMT. The time now is 06:51 AM.


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