w15cy in a voigt pipe - 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 26th August 2009, 09:11 PM   #1
sergiof is offline sergiof  Portugal
diyAudio Member
 
Join Date: Sep 2005
Default w15cy in a voigt pipe

good evening (and by the way, happy birthday!)

it's been a while since i started to whirl my mind into a sound system of which i would really be proud of. my first idea was to prepare a 3way loudspeaker, using a transmission line bassbox, in order to reach as low as possible (with good quality, obviously). for this, i had the incredible help of pkitt, to whom i'd like to say "thank you" once again.

the problem started when i decided to show my idea to my girl... well, the boxes are huuuuuuge, so i believe you're understanding what the situation is...

therefore, i came up with the idea of building up a pair of 2way loudspeakers (seas w15cy + fountek jp3 - digital crossover), plus a huge subwoofer, also controled by this crossver (in a rectangular prism shape, that would be discretely positioned near a wall)...

for the subwoofer i'll continue asking the precious help of pkitt in the mentioned topic (fiberglass TL). for the 2way speaker, i was thinking on a voigt pipe made out of fiberglass (for the seas W15CY), that would look something like... the B&W emphasis...

the problem is i never made a voigt pipe loudspeaker before, and the info i found is not very helpful (for a rookie like me) to design it... can some of you please help me designing something that "not bended" would look very much like an icecream cone?

thank you very much!
  Reply With Quote
Old 26th August 2009, 09:40 PM   #2
diyAudio Member
 
Scottmoose's Avatar
 
Join Date: Mar 2005
Location: UK
You could try this mass loaded horn (or Voigt pipe if you prefer) as a starting point.

60in long; St=0in^2 (i.e. it comes to a point at the top), Sl = 42.25in^2 (suggest 6.5in x 6.5in). Driver down 30in from the throat. Vent centre 1in up from terminus, vent 2in diameter x 3.75in long. Line entire cabinet with 1in 'stiff' acoustic fibreglass & adjust this & vent tuning to requirements.
  Reply With Quote
Old 26th August 2009, 10:24 PM   #3
sergiof is offline sergiof  Portugal
diyAudio Member
 
Join Date: Sep 2005
vent?
hummmm... i was expecting it to be completely opened in the throat... horn-like kind of pipe (maybe i'm really talking about a horn)

[EDIT: as an example of what i was expecting...]
Click the image to open in full size.

[and these are the B&W Emphasis... gorgeous looking speakers]
Click the image to open in full size.

Last edited by sergiof; 26th August 2009 at 10:38 PM.
  Reply With Quote
Old 26th August 2009, 11:13 PM   #4
sergiof is offline sergiof  Portugal
diyAudio Member
 
Join Date: Sep 2005
ah, i ended up finding the BIB calculator... that's what i intended...

just one question: i used the Thiele-Small parameters given by John Krutke, and then i compared to the ones given by Seas and... shock! one has nothing to do with the other!

Seas/ZaphAudio
Fs: 38Hz/53,70Hz
Vas: 14L/6,20L
Qts: 0,36/0,53

is this normal???
  Reply With Quote
Old 26th August 2009, 11:13 PM   #5
diyAudio Member
 
Scottmoose's Avatar
 
Join Date: Mar 2005
Location: UK
Well, there you go, although a BIB typically is folded once, so the cabinet is actually rectangular.

As for T/S variations, yes, that's normal; it often depends on exactly how they were measured.

Last edited by Scottmoose; 26th August 2009 at 11:16 PM.
  Reply With Quote
Old 26th August 2009, 11:34 PM   #6
sergiof is offline sergiof  Portugal
diyAudio Member
 
Join Date: Sep 2005
i'm sorry, i really had the idea that these kind of boxes (the BIB ones) were voigt pipes... my mistake...

thank you for your patience!
  Reply With Quote
Old 27th August 2009, 08:30 AM   #7
diyAudio Member
 
Scottmoose's Avatar
 
Join Date: Mar 2005
Location: UK
Oh yes; they're just a tapped conical horn set to 1/2 wave tuning rather than 1/4 wave. They're still essentially Voigt style cabinets. Note that the BIB is a corner-horn design; it needs corner-loading to work properly.
  Reply With Quote
Old 27th August 2009, 03:51 PM   #8
GM is offline GM  United States
diyAudio Member
 
GM's Avatar
 
Join Date: Jun 2003
Location: Chamblee, Ga.
Technically, they are tuned to a 1/4 WL of some predetermined frequency since all pipes/horns have a 1/4 WL fundamental, but an open pipe or an expanding or contracting horn is a 1/2 WL resonator, so must be acoustically a 1/2 WL long once any boundary loading is factored in to get max loading to the desired F3.

From this we see that both of the Voigt (pipe) horns shown above will have a relatively high F3 with the understanding that what makes them a Voigt patent design is their use of a point source driver to back load a horn. Apparently, RCA didn't bother to cross patent their decade plus earlier designs with other patent offices. What makes his patent unique though AFAIK is the concept of loading the (pipe) horn somewhere along its length that best matches the driver's electro-mechanical-acoustical properties to achieve the flattest/widest BW practical.

GM
__________________
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
  Reply With Quote
Old 27th August 2009, 04:12 PM   #9
GM is offline GM  United States
diyAudio Member
 
GM's Avatar
 
Join Date: Jun 2003
Location: Chamblee, Ga.
Quote:
Originally Posted by sergiof View Post
is this normal???
These days, unfortunately, though there are (were) some manufacturers that did/do publish specs that while what you bought doesn't match per se, will work fine in cabs designed using published specs and one reason why I have always preferred prosound drivers. For others I typically ignored any specs and designed based solely on driver Sd and measured Fs.

With the design routine I used, the cabs were initially over-sized to a greater or lesser extent, though all could be adjusted in-room via vent damping and/or some form of electrical bass tone control, so for me, the theoretically main advantage of the T/S way of designing is getting the minimum speaker bulk for a given gain BW, and yet the few A/B comparisons I made, I found that technically under-damped designs sounds more life-like to me once tuned in-room even if they may not measure as the most technically correct/efficient based on the driver's T/S specs.

GM
__________________
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
  Reply With Quote
Old 27th August 2009, 09:56 PM   #10
sergiof is offline sergiof  Portugal
diyAudio Member
 
Join Date: Sep 2005
the biggest problem in searching for new loudspeaker enclosures (seen by me, as i believe these kind of enclosures exist for ages), specially when i'm far to be an acoustic engineer, is that i always end up being a rookie in any new approach i try...

so please, i beg you your patience (and believe in me, i'm learning with interest)...

i understood most everything both of you wrote except the sentence: "Note that the BIB is a corner-horn design; it needs corner-loading to work properly.". i'm gonna search for info in the BIB website i went before, but on the meantime, may i leave this as a question?

thank you!

[I saw... still, as this is gonna be an expensive experience, do you recomend me this approach for the project in mind?]

Last edited by sergiof; 27th August 2009 at 10:02 PM.
  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
The Winged Voigt Pipe - Good for Nothing? rjbond3rd Full Range 6 1st April 2008 09:50 PM
Folded Voigt Pipe Ropie Full Range 18 2nd November 2005 03:31 PM
MTM on a Voigt Pipe ? johninCR Full Range 2 8th April 2005 06:20 AM
Test run of 2-way Voigt Pipe Timn8ter Multi-Way 11 21st January 2004 04:17 PM


New To Site? Need Help?

All times are GMT. The time now is 05:57 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