Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Multi-Way Conventional loudspeakers with crossovers

A Bookshelf Multi-Way Point-Source Horn
A Bookshelf Multi-Way Point-Source Horn
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 9th January 2016, 02:12 PM   #1
xrk971 is online now xrk971  United States
diyAudio Member
 
xrk971's Avatar
 
Join Date: Oct 2012
Location: Metro DC area
A Bookshelf Multi-Way Point-Source Horn
Default A Bookshelf Multi-Way Point-Source Horn

This originally started in this thread which asks the question "why aren't we building a bookshelf synergy monitor" and answers it with "we are" or at least "let's try and see what we get."

I got inspired back in the Trynergy thread to build a semi bookshelf point source horn

The results with the SB Acoustics SB65WBAC25-4 were very encouraging that Bushmeister went and ordered the drivers and some off the shelf waveguides to start experimenting.

So here is sort of my vision of the end goal. It's all very fluid and we try to make things smaller where possible. The reality is it might be closer to a small stand mount. Decisions of which WG to bass the system on sets overall size.

Click the image to open in full size.

Thanks to Bushmeister for the willing spirit to tackle this project. We are going to work together to come up with a new speaker with development and plans happening in real time ad hoc. It starts with Bushmeister picking the off the shelf 18 Sound waveguide.

Here is a summary of the completed speaker built by Bushmeister.

I guess we are calling the "XBush". Post 1248

Some highlights of the XBush:

Predicted sensitivity and response before EQ using a Harsch XO at 500Hz and SB23NRXS45-8 woofers:
Click the image to open in full size.

The business side of the horn normally not visible when boxed up:
Click the image to open in full size.

Mounted inside cabinet:
Click the image to open in full size.

Finished speaker:
Click the image to open in full size.

Acoustic XO slopes for Harsch:
Click the image to open in full size.

Harmonic distortion at 100dB and 1m (nice!). Note that this is just a 2-wa speaker with two sealed 8in drivers - that manage to produce nice deep bass extension with low distortion:
Click the image to open in full size.

Measured acoustic phase:
Click the image to open in full size.

Measured Horizontal Polar Directivity:
Click the image to open in full size.

Measured Vertical Polar Directivity:
Click the image to open in full size.

Step Response:
Click the image to open in full size.

Measured Group Delay:
Click the image to open in full size.


######### XRK971's XBUSH ############

Not fully up to snuff yet when compared to Bushmeister's amazing effort, but here is Xrk971's attempt which uses a Faital Pro LTH142 waveguide, dual Dayton RS180P-8 woofers, and same SB65WBAC25-4 mid/tweeter:

Internals with all 3d printed driver to horn adapters (here shown with early version using DC200-8 wofoer):
Click the image to open in full size.

Later version with RS180P-8 woofers:
Click the image to open in full size.

Detail of SB65 throat adapter:
Click the image to open in full size.

CAD drawing of adapter:
Click the image to open in full size.

Fitting into box for first time:
Click the image to open in full size.

Measured Polar directivity of SB65 in LTH142 waveguide:
Click the image to open in full size.

3d printed woofer to waveguide adapter:
Click the image to open in full size.

3d printed woofer chamber volume reducer plug:
Click the image to open in full size.

Polar directivity with woofer holes:
Click the image to open in full size.

Click the image to open in full size.

Used in stereo with uTrynergy on left and Xrk's speaker on right:
Click the image to open in full size.

Acoustic XO slopes of Xrk's speaker:
Click the image to open in full size.

Phase of Xrk's speaker (still working on getting it flatter and proper 55deg phase bump for Harsch):
Click the image to open in full size.

Harmonic Distortion of Xrk's speaker (not very good - many leagues below what Bushmeister is able to do):
Click the image to open in full size.

I suspect the higher HD has to do with a number of things including: driver choice, cabinet volume and wall material, cabinet resonance damping methods, waveguide inertness via 4kg of epoxy Bondo, and larger holes (60mm vs equiv 29mm).
All pieces and adapters on Xrk's speaker were 3d printed PLA vs hand cut and epoxy for Bushmeister's excellent effort. Sometimes low tech gives better results.

So, my speaker is still a project waiting for more work to improve the phase, the step response, and improve the harmonic distortion.

Last edited by xrk971; 11th March 2016 at 06:36 PM.
  Reply With Quote
Old 9th January 2016, 09:00 PM   #2
xrk971 is online now xrk971  United States
diyAudio Member
 
xrk971's Avatar
 
Join Date: Oct 2012
Location: Metro DC area
A Bookshelf Multi-Way Point-Source Horn
Default Overall Plan

Here is sort of how I am wishfully thinking it will look after Bushemeister is through with it...

Click the image to open in full size.
Attached Images
File Type: png Bookshelf-multiway-point-source-horn-schematic.png (314.8 KB, 6303 views)
  Reply With Quote
Old 9th January 2016, 10:31 PM   #3
Soldermizer is offline Soldermizer  United States
diyAudio Member
 
Soldermizer's Avatar
 
Join Date: Feb 2012
Location: Tamper, FL, USA
I'm waiting! :-)

Sent from my SPH-L300 using Tapatalk
__________________
My waveguide is an Elated Obligatory Spheroid
  Reply With Quote
Old 9th January 2016, 10:37 PM   #4
xrk971 is online now xrk971  United States
diyAudio Member
 
xrk971's Avatar
 
Join Date: Oct 2012
Location: Metro DC area
A Bookshelf Multi-Way Point-Source Horn
Bushmeister is waiting on delivery of SB65's from Germany. Apparently they are taking their sweet time.

I'm all talk on this thread so all wood cutting and gluing etc is vicariously enjoyed via Bushmeister's expert hands.
  Reply With Quote
Old 9th January 2016, 11:40 PM   #5
BYRTT is offline BYRTT  Denmark
diyAudio Member
 
Join Date: Dec 2009
A Bookshelf Multi-Way Point-Source Horn
That is interesting sketch of your thinking xrk971, it looks bit complicated build but as we hope if tweeter and mid woofer will integrate perfect into point source horn then it will be worth the many build details.
  Reply With Quote
Old 10th January 2016, 12:22 AM   #6
xrk971 is online now xrk971  United States
diyAudio Member
 
xrk971's Avatar
 
Join Date: Oct 2012
Location: Metro DC area
A Bookshelf Multi-Way Point-Source Horn
It's fun to go wild when someone else has to make it.

It's really 3 way sealed speaker with tweeter and mids going out of horn and woofer is big sealed box firing down. Box can be made simple rectangular prismatic but where's the fun in that. . Also really I am trying to keep volume small and size visually slimmer.
  Reply With Quote
Old 10th January 2016, 03:13 AM   #7
BYRTT is offline BYRTT  Denmark
diyAudio Member
 
Join Date: Dec 2009
A Bookshelf Multi-Way Point-Source Horn
Sealed three way monitor bushmeister linked the other thread is serius speaker build, looks a good reference to compare Bookshelf Multi-Way Point-Source Horn.

Discovered my WinSpeakerz program can model band pass box so for fun did model SB12NRX25-8 in Q 0,7 sealed verse same having a band pass front box and port. xrk971 if you find time could you run Akabak and see if it agree frq response for band pass setup, data used is 32 watt input, 1,999 liter back box volume, 0,05 liter front box volume, port diameter 34mm, port length 30mm, front box resonance 1000Hz, BW2 low end roll off for sealed example is 108,9Hz for band pass looks more like 88Hz with a couple dB lost sensitivity verse ordinary sealed.
Attached Images
File Type: png 1.PNG (86.6 KB, 302 views)
  Reply With Quote
Old 10th January 2016, 03:30 AM   #8
xrk971 is online now xrk971  United States
diyAudio Member
 
xrk971's Avatar
 
Join Date: Oct 2012
Location: Metro DC area
A Bookshelf Multi-Way Point-Source Horn
Thanks for running that Byrtt. Once it couples into the horn - the behavior may be different in that horn adds a few more dB mostly due to directionally because of horn. There will be overshoot peak from port but that can be EQ'd out. Does look like 500Hz is a good XO point. I need to estimate to expansion profile of the 18Sound WG and put that geometry into the model for Akabak to predict this well. I guess it's time to put some simulation to this to predict bandpass hole size and location for optimum results.

Yes, seeing Bushmeister's work on that very formidable 3 way sealed box gives me high confidence we are going to get this horn to work well.
  Reply With Quote
Old 10th January 2016, 03:47 AM   #9
ra7 is offline ra7  United States
diyAudio Member
 
Join Date: Feb 2009
A Bookshelf Multi-Way Point-Source Horn
I admire the spirit of X and also am a little jealous of the speed with which he builds speakers. Wish I could turn all my wild ideas into actual builds this fast.

The point of the synergy horn is controlled directivity in the low frequencies. This, by design, means the mouth of the horn must be large and the horn itself must be relatively large. The lower in frequency you want to control where the sound goes, the bigger the horn must be. As diyers we can build whatever size speakers we want. But can we really call these "bookshelf?"
  Reply With Quote
Old 10th January 2016, 04:13 AM   #10
xrk971 is online now xrk971  United States
diyAudio Member
 
xrk971's Avatar
 
Join Date: Oct 2012
Location: Metro DC area
A Bookshelf Multi-Way Point-Source Horn
For me, this is a FAST horn and if I can get controlled directivity down to the bottom of the full range at 500Hz I am good. That cleans up the ambient spray a lot.

But like I said, it depends on how big your books are

There's no reason why we can't all build crazy new speakers fast and all the time. For me it was lack of workshop so I use foam and glue.

I had a crash course in designing and building over 3 dozen speakers in past 3 years. I average 1 a month. Not that fast - some people whip out wood speakers in a few days. But trying new things is fun. The Synergy was a challenge but doable in foam.

Last edited by xrk971; 10th January 2016 at 04:17 AM.
  Reply With Quote

Reply


A Bookshelf Multi-Way Point-Source HornHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
SynTripP: 2-way 2-part Virtual Single Point Source Horn weltersys Multi-Way 595 Today 05:17 AM
Red Spade PSE-144 unity ,point source elliptical Horn, w/xover, 250-20khz hum4god Swap Meet 10 13th February 2016 04:30 PM
Need Help with Point Source Monitor!!! MikeDavidBeats Multi-Way 8 30th January 2014 06:02 PM


New To Site? Need Help?

All times are GMT. The time now is 02:09 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio
Wiki