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

Open baffle form factor questions
Open baffle form factor questions
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 January 2020, 04:56 AM   #1
aagas is offline aagas
diyAudio Member
 
Join Date: Jul 2013
Default Open baffle form factor questions

A few years ago I pressed a pair of old Pass A40 stereo amps into service again. I bridged them so I had a pair of mono amps and fitted them into the base of an open baffle speaker project based on the Pure Audio Projects Trio15 Beyma TPL-150H.

I've attached a file with a few snaps of an early stage of the project.
I've grown very fond of these speakers, but I fear my aged A40s will rapidly approach the end of their useful life.
As such I've started to think about replacing the A40s and I thought I'd take the occasion to rework the speakers too.

I came across the Spatial Audio X3s . See 1st attachment.

It strikes me that Spatial has designed a form factor for open baffle speaker, that one might readily adapt to a DIY speaker project.

You can see from the attached snaps that the speaker appears to have 2 baffles. The front one (wood colored) mounts the drivers and a second described on Spatial's website as:
"A secondary sub-baffle provides resonance draining properties and houses the isolated mid/high passive crossover and integrated N-Core power amplifier which drives the subwoofer.
I'd like to replicate something like these speakers (at least visually) using the drivers I currently have, so...

Does anyone have any thoughts on how to "isolate" the "secondary sub-baffle" and what material to make it from?

In what I've begun to imagine, I think I would use three amps per speaker and digital crossovers. I think this would provide a great deal of design flexibility.

Finding room to mount all of this will likely take some ingenuity. I do like the idea of having all the components mounted in the monolithic double baffles and the baffles supported by a simple stand. My wife, an architect with minimalist sensibilities would prefer such a design.

Any recommendations on how to go about this appreciated.
Attached Images
File Type: png Screen Shot 2020-01-10 at 5.45.40 PM.png (429.2 KB, 366 views)
File Type: png Screen Shot 2020-01-10 at 5.45.27 PM.png (238.4 KB, 369 views)
  Reply With Quote
Old 11th January 2020, 07:35 AM   #2
LineSource is offline LineSource  United States
diyAudio Member
 
LineSource's Avatar
 
Join Date: Sep 2003
Location: SiliconValley
The BMF-1 speaker custom-built by Tweek Geek Colorado audio Boutique has received high praise in public shows. The use of two-sealed, near-floor, side-side, counter-force, DSP-controlled woofers provides powerful deep bass in a medium size 6cuft cabinet. The BMF-1 stands 43”high x 16”wide x 20”deep. The Tweek Geek website has several construction pictures,

You would need to purchase 12" midranges like the $230 Faital 12PR320, or if cost is an issue the $130 Eminence DeltaPro 12A, and an electronic crossover plus high power bass amp to drive two of your 15" woofers in a sealed and bass-equalized bottom cabinet section.

ASSUMPTIONS:
1) Great sound is more important than having the 2001 Monolith in your living room.
2) You own TPL-150H and four 15" Eminence woofers.
3) The controlled directivity generated by the TPL-150H horn tweeter is the key sonic signature.
4) You and your wife can customize the final shape, dimensions, and finish.
-Equal volume from tall and shallow cabinet?
-Plywood? Black? White?
-Large radius edge cuts? (1.5" radius router bit ~$130)
---Monolith or "big rounds JukeBox"
Attached Images
File Type: jpg BMF_1.jpg (85.0 KB, 349 views)
File Type: jpg low diffraction 18in wide.jpg (259.6 KB, 330 views)
  Reply With Quote
Old 11th January 2020, 04:22 PM   #3
aagas is offline aagas
diyAudio Member
 
Join Date: Jul 2013
@LineSource --

Thanks for your input. Like some others in these forums, I have a particular interest in Open Baffle design. As stated in my opening post:

Quote:
I'd like to replicate something like these speakers (at least visually) using the drivers I currently have
I see this as an incremental improvement to the speakers and components I already have rather than a completely new ground up build.

Everything has tradeoffs. For what I want to try to build I seek:

Quote:
...thoughts on how to "isolate" the "secondary sub-baffle" and what material to make it from...
Also, and something I ought to have specifically requested...

Recommendations on digital crossovers and plate amplifiers that would make sense for what I have described.


I will check the BMF-1 speaker info to see what they use for DSP. It could prove a useful source of information.

P.S. -- Can anyone recommend a digital crossover discussion on this forum to better familiarize myself?
  Reply With Quote
Old 11th January 2020, 04:52 PM   #4
CharlieLaub is offline CharlieLaub  United States
diyAudio Member
 
Join Date: Mar 2007
Location: Michigan
If you want to rework the speakers and get better sound, I posted some design ideas in this post:
Multi-way OB

As you can see the PAP style and other large OB speakers don't follow this design philosophy. I think they have built in some flaws as a result, but the speakers look very attractive and impressive and that is what many "audiophiles" seem to value in their gear as much as or even more than the actual performance.
__________________
Visit my Audio Web Page <<--CLICK TO LEARN MORE-->> Get my LADSPA plugins
  Reply With Quote
Old 11th January 2020, 04:55 PM   #5
scottjoplin is offline scottjoplin  Wales
diyAudio Member
 
scottjoplin's Avatar
 
Join Date: Dec 2015
Location: Penrhyndeudraeth
They look like Eminence drivers, but they've given them their own name?
  Reply With Quote
Old 11th January 2020, 05:24 PM   #6
aagas is offline aagas
diyAudio Member
 
Join Date: Jul 2013
@scottjoplin -- If memory serves, PAP had Eminence modify drivers for Open Baffle application.
  Reply With Quote
Old 11th January 2020, 06:14 PM   #7
scottjoplin is offline scottjoplin  Wales
diyAudio Member
 
scottjoplin's Avatar
 
Join Date: Dec 2015
Location: Penrhyndeudraeth
Thanks
  Reply With Quote
Old 12th January 2020, 12:44 AM   #8
Patrick Bateman is offline Patrick Bateman  United States
diyAudio Member
 
Patrick Bateman's Avatar
 
Join Date: Oct 2006
Location: San Diego
I imagine that the founder of Spatial Audio and Emerald Acoustics frequents this forum.

If he does, he's probably making the baffle out of a constrained-layer-damping composite.

There's a number of threads on here about how to do it.

On a side note, I've heard both and they sound really nice.
  Reply With Quote
Old 12th January 2020, 05:20 AM   #9
LineSource is offline LineSource  United States
diyAudio Member
 
LineSource's Avatar
 
Join Date: Sep 2003
Location: SiliconValley
Baseball allows 3-strikes. Here is my second controlled directiviy pitch....
Sealed 0.5cuft TM cabinet between the Top and Bottom dipole woofers.
=====
The soundstage changes created from a crossover between a monopole 80H x 40V horn loaded tweeter directly to a large diameter dipole driver will be noticed by most listeners.

A 0.5cuft sealed box tweeter-midrange cabinet using the TPL-150H crossed at 1800Hz to the 8" Faital 8PR200-8 crossed at the 120Hz baffle step frequency to the dipole woofers provides a more gradual change from 180-degree monopole baffle to 360-degree full room directivity
Attached Images
File Type: jpg Sealed M and T box.jpg (86.0 KB, 266 views)
  Reply With Quote
Old 12th January 2020, 06:48 AM   #10
silent mike is offline silent mike  Canada
diyAudio Member
 
Join Date: Dec 2005
Location: Salt Spring Island, BC
Quote:
..."isolate" the "secondary sub-baffle" and what material to make it from...
It's difficult to see clearly just how the 2 panels are mounted together. The first panel is obviously similar to multiple stacked BB plywood, which has rigidity advantages but a bit of a pain to make. The second could be anything, but the big question to me is how the two panels connect together. My guess is the front baffle has to have a firm secure mechanical connection to the metal feet/stand. That suggests the 2nd panel could be decoupled?, despite the look of the shiny metal disc connectors between them -- and perhaps it is some kind of internally well-damped panel. The simplest effective rigid damped composite panel a DIYer can make is to bond two layers of relatively thin (say 9mm?) BB ply with Green Glue -- the acoustic damping goop which also doubles as glue. It does work.

Relatively cheap and simple to try.

Whether you'll hear any real improvement depends, most likely, on how much panel vibration is affecting the performance of your current setup -- and how much reduction of such vibration the new arrangement provides. Assuming you keep the panel/driver arrangement otherwise the same. You might want to invest in a vibrometer to get some empirical evidence one way or the other.

Personally, I'm not convinced a secondary panel like that is necessary for either a vibration sink or to house electronics. The old right-angle ledge on the back bottom of the speaker like on so many electrostatics etc seems a fine place for such things. And I'd be more interested in using a constrained damped layer panel as the baffle rather than try to pull vibrational energy out of it after it's already been "excited". Just my 2 cents.

Quote:
three amps per speaker and digital crossovers
The simplest way to do this is a Hypex FusionAmp FA123 or similar 3 ch + DSP plate amp per spkr. When implemented, it should at least match your current amp + passive xover setup and likely far exceed it.
  Reply With Quote

Reply


Open baffle form factor questionsHide 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
WTB: GrubDAC or similar form factor USB DAC populated PCB HiGHFLYiN9s Swap Meet 2 3rd November 2014 11:12 AM
HIFI sound in zvox form factor? Lefty78 Multi-Way 3 29th March 2013 03:27 PM
Open baffle servo vs. high damping factor fudce Multi-Way 0 22nd March 2013 02:54 AM
Visaton Quadro questions. Box to Open baffle and other questions. Bas Horneman Full Range 2 1st March 2013 11:53 AM
zaph's BAMTM form factor gonar Multi-Way 0 2nd January 2007 08:01 PM


New To Site? Need Help?

All times are GMT. The time now is 06:41 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Copyright ©1999-2020 diyAudio
Wiki