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 Monster Construction Methods Shootout Thread
A Monster Construction Methods Shootout Thread
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 17th June 2020, 07:47 PM   #1
augerpro is online now augerpro  United States
diyAudio Member
 
Join Date: Aug 2006
Default A Monster Construction Methods Shootout Thread

Which wood to use? Which fill? What does bracing do? Is CLD best? I'm starting this project to start quantifying some answers to these questions. A lot of work has been done before in fits in starts by others (BBC, Kef, etc.) but they were often narrow investigations and you couldn't compare results because measurement conditions were different among the different studies. Some have cited manufacturer's damping specs, but I have no idea how that translates to the real world. Ditto on accelerometer data. So here I will be doing SPL measurements, that is after all, what we actually hear. The cabinet is ordinary, large enough for the panels to have some radiating area and magnify differences between changes.

Click the image to open in full size.

I will be using a Peerless 830970 firing into the cabinet using MLS signals. I have to test mic placement, but it will probably end up near-ish field, probably at a side panel. When I do the fill/lining I will mount the SB15 as a dummy woofer and measure what radiates through it. I intend to measure SPL, CSD, and THD. Any other recommendations appreciated.

For the material test I currently have: high and low quality plywood in 1/2" and 3/4", and MDF in 1/2" and 3/4".

For the fill and lining I have: SDS CLD tiles, AcoustX coating, denim insulation, polyfill, 1" thick dacron blanket (what the TL guys use) and Sonic Barrier.

For bracing I will do: simple oak crossbrace versus oak crossbrace using CLD construction with Sikaflex 292i adhesive. I also have some microspherules to combine with the adhesive to see how that changes things.

I would appreciate all suggestions on any other additions to the above. A priority will be that the materials must be widely available and reasonably priced, and the methods must be accessible to an ordinary DIYer.
__________________
~Brandon
Please help my waveguide and box construction research by donating to my gofundme via my website:Soma Sonus
  Reply With Quote
Old 17th June 2020, 09:12 PM   #2
NiToNi is offline NiToNi  United Kingdom
diyAudio Member
 
Join Date: Oct 2004
Wow, subscribed
  Reply With Quote
Old 18th June 2020, 03:55 AM   #3
hifijim is offline hifijim  United States
diyAudio Member
 
hifijim's Avatar
 
Join Date: Sep 2019
Location: St Louis, MO
Looks like we will all learn something.

Quote:
When I do the fill/lining I will mount the SB15 as a dummy woofer and measure what radiates through it.
I recommend testing with the SB15 terminals shorted. I think this would represent a low-output-impedance amp (yes?) and also with terminals open. I am curious how much the amplifier controls sound transmision through the cone above resonance frequency.
  Reply With Quote
Old 18th June 2020, 04:20 AM   #4
mainframe99 is offline mainframe99  New Zealand
diyAudio Member
 
Join Date: Jan 2019
I won't comment on the construction method of that Audi - but I'm watching this. Very interesting!
  Reply With Quote
Old 18th June 2020, 06:14 AM   #5
Mindsource is offline Mindsource  Canada
diyAudio Member
 
Join Date: Aug 2015
Location: Canada
A Monster Construction Methods Shootout Thread
Glad you are trying sikaflex with microspheres. As I’m sure you know, Geddes used two part shore A + microspheres in approx 1:1 ratio. But for the average home gamer the two part PU is expensive and hard to work with. Sikaflex + microspheres in 1:1 ratio is what the average diy’er would have access to. Maybe you would be willing to try the sikabond construction adhesive as well. It’s has similar specs to the 292i, but is easier to find and is a fraction of the price.

Last edited by Mindsource; 18th June 2020 at 06:19 AM.
  Reply With Quote
Old 18th June 2020, 02:50 PM   #6
Baldin is offline Baldin  Denmark
diyAudio Member
 
Baldin's Avatar
 
Join Date: Jan 2005
Location: Copenhagen
Great stuff. Subscribed.

I'll try to dig out some material which might be helpful .... seem to recall some German sites with quite through investigation, test and sound examples.

Besides measurements, it would be nice with some kind of sound samples for us to hear .... not sure how or what ... just a thought
  Reply With Quote
Old 18th June 2020, 02:55 PM   #7
Mindsource is offline Mindsource  Canada
diyAudio Member
 
Join Date: Aug 2015
Location: Canada
A Monster Construction Methods Shootout Thread
Maybe good to construct a good non CLD box, get it to resonate, then CLD brace it and use tape accelerometer to see if resonance goes down.

Also for fill, might want to try pink fiberglass. If you look in the window seal and door sweep section you can sometimes find small packs that are perfect size to fill a few speakers, instead of buying the big pink panther bags.

Last edited by Mindsource; 18th June 2020 at 03:04 PM.
  Reply With Quote
Old 18th June 2020, 03:00 PM   #8
454Casull is offline 454Casull  Canada
diyAudio Member
 
Join Date: Jan 2004
Location: Toronto, ON, Canada
Alright! Looking forward to the progress and results.
  Reply With Quote
Old 18th June 2020, 06:36 PM   #9
augerpro is online now augerpro  United States
diyAudio Member
 
Join Date: Aug 2006
To answer some comments in another thread: the SB15 will only be used when testing fill or soft lining to simply see what radiates back out of the box due to internal dampening. For box material and methods (CLD), and bracing, there will be no SB15 mounted (or even a hole for it). Just the Peerless driver.
__________________
~Brandon
Please help my waveguide and box construction research by donating to my gofundme via my website:Soma Sonus
  Reply With Quote
Old 18th June 2020, 06:49 PM   #10
454Casull is offline 454Casull  Canada
diyAudio Member
 
Join Date: Jan 2004
Location: Toronto, ON, Canada
Quote:
Originally Posted by augerpro View Post
I will be using a Peerless 830970 firing into the cabinet using MLS signals. I have to test mic placement, but it will probably end up near-ish field, probably at a side panel.
Will you consider also doing acoustic SPL measurements at 1 m distance from a side panel as well, and especially at varying angles? If we treat the side panel as a diaphragm that vibrates mostly in phase, it would be very interesting to see whether there is constructive or destructive interference "off-axis" that might impact how people hear the sound of the enclosure at the listening position.
  Reply With Quote

Reply


A Monster Construction Methods Shootout ThreadHide 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
JLH Mosfet Power amplifier construction thread jamesfeline Solid State 56 15th August 2020 09:28 AM
Studio 350 construction thread jamesfeline Solid State 49 30th September 2019 09:19 AM
monster-6-channel-amplifier-build-thread matt09 Solid State 8 12th April 2016 09:44 PM
Krill construction thread - Sidetracked quoydoy The Lounge 43 12th March 2009 07:51 PM
Ultimate NOS DAC Construction Thread iggy80fr Digital Source 1 11th November 2007 04:14 PM


New To Site? Need Help?

All times are GMT. The time now is 11:57 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Copyright ©1999-2020 diyAudio
Wiki