Go Back   Home > Forums > >

Multi-Way Conventional loudspeakers with crossovers

A 3 way design study
A 3 way design study
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
Old 26th September 2021, 07:01 PM   #71
Juhazi is offline Juhazi  Finland
diyAudio Member
 
Juhazi's Avatar
 
Join Date: Mar 2007
Location: Jyväskylä
chamfering driver holes

Click the image to open in full size.
__________________
Radikal aktivist AINOgradient speaker project
  Reply With Quote
Old 26th September 2021, 07:42 PM   #72
augerpro is offline augerpro  United States
diyAudio Member
 
Join Date: Aug 2006
tmuuikku> I would be interested in your results of the sine wave test to determine audibility. I'm not against this concept, possibly it would be preferred under some circumstance. I just doubt it should be generally followed in all cases. I'll have to look into Kimmosto's work more, that linked post is really just making claims, I need to understand the conditions that underpin those claims.

HifiJim> your comment reminded me of another thing I haven't liked about tweeters too far from the mid and that was for voices and some instruments to "wander" back adn forth between drivers instead of sounding like they come from one point in space.

Vineeth> here's my quick and dirty recommendation on the box: at least do a simple CLD construction where you use two panels glued together with Weicon Flex 310M Classic (or SikaFlex 291 if you can't source the Weicon). This single factor made more difference in my testing than what wood you used or even the thickness.

CLD braces are also easy to do, so do that (see my website for examples, I'm testing some more today). I would apply Resonix tiles, but I'm not sure you can get that. Someone here can probably link a generic version for home construction. Beware they don't all perform the same though. Then I would line the walls with 100% wool batting for quilts at @ 1.5" thickness. You can find this online easily enough. I have a link to a Euro source at my website.

EDIT: just noticed you are doing sealed boxes. I still like the wool as fill for this. Or the type of dacron batting that Meniscus Audio sells.
__________________
~Brandon
Please help my waveguide and box construction research by donating to my gofundme via my website:Soma Sonus
  Reply With Quote
Old 26th September 2021, 08:15 PM   #73
tmuikku is online now tmuikku  Finland
diyAudio Member
 
Join Date: Sep 2004
Location: Savo, Finland
Send a message via ICQ to tmuikku
^ Yes your doubt is right, the wl spacing trick depends on the listening environment. Point is to have same spectra on the early reflections as the direct sound.

I spent time for you and found few links that have free discussion about it. If you have time to read the few pages linked you'll get the rationale behind "the c-c rule", when it should be applied and where Kimmosto got the numbers.

Here the whole page kind of relates:
Some help with lobing | Page 2 | Audio Science Review (ASR) Forum

Here scroll down some to get to the relevant discussion
VituixCAD v2 - Page 6

I'm not very good explaining in english, hopefully these help

Last edited by tmuikku; 26th September 2021 at 08:18 PM.
  Reply With Quote
Old 27th September 2021, 11:24 AM   #74
vineethkumar01 is offline vineethkumar01  India
diyAudio Member
 
Join Date: Aug 2019
Thanks everyone for the tips so far.

@Augerpro: Thanks a lot. I will try to source the Weicon Flex or Sikaflex adhesives, but I fear it would very expensive here in India. The last time I checked, buying 1.5 litre volume of the adhesive will cost me more than both the tweeters combined. And the above volume of adhesive itself may not be enough to build two close to 60 -70L volume floor standing speaker boxes.
So I wanted to know if any general category of adhesives are preferred for this CLD application. If there is such a thing, maybe I can look at a brand which is more locally available.

Another question that I have is, on your website you had remarked that CLD box + CLD brace didn't complement each other as you had hoped. Does it mean that both need not/should not be used in a box construction application?
Or should the midrange box be made as a CLD box and the woofer box as a regular box with CLD bracing
Or can I make a full CLD box with separate partition for mid and CLD bracing applied more in the woofer compartment

I dont see the CLD tiles you mentioned available here yet. Maybe I can apply some sound dampening alubutyl sheets and hope for the best. Regarding wool/dacron for cabinet fill, I will definitely source this.

@Juhazi: Thanks for the chamfering tip. I will definitely do this. since the intended front baffle itself is about 50mm thick, chamfering will make a lot of sense with the mid driver and probably the woofer.

@tmuikku: Thanks again for providing all these posts showing Kimmosto's reasoning behind the 1.2x spacing rule. I am definitely learning more but also I just get confused more
At my home, I may probably never have a chance to listen to these speakers more than 2.5m away, since rooms are relatively small and walls are relatively close.Kimmosto himslef says close c-c/coaxial is better for nearfield listening. Is there any rule which specifies what is nearfield/farfield with respect to a home listening environment like mine..
  Reply With Quote
Old 27th September 2021, 11:45 AM   #75
tmuikku is online now tmuikku  Finland
diyAudio Member
 
Join Date: Sep 2004
Location: Savo, Finland
Send a message via ICQ to tmuikku
I think the definition for nearfield listening is that the direct sound is louder than the reverberant sound from the room, but you would have to check the true meaning. This is relevant enough definition in this context I think.

The kimmosto c-c rule is basically related to the quality of the reflected sound. Reflected sound is not too important if you are nearfield or have acoustic treatment in your room, in other words reflected sound is minimized to the listening position.

The louder the first reflection (ceiling/floor) is the more relevant it is to mind about their sound signature. Here the c-c could matter, you could arrange the lobing so that the reflected sound (from ceiling and floor) has similar sound signature as the direct sound.

When there is big main lobe, drivers as close as possible c-c, the first reflections from ceiling/floor might happen through the off-axis null and will sound different than the direct sound. You can use the c-c distance adjustment as advantage in this situation by steering the off-axis null so that it is not on the way of first reflections. Now the first reflection from the ceiling/floor has similar sound as the on-axis. The CTA-2034 standard rates the off-axis, first reflection, sound very important in situation where it is prominent, explained in the quote few pages back.

I'd say you just have to build something and if it doesn't sound good enough you have a possibility to explore here.

Hope this clarifies it After all, it is just common sense thinking whether to use it or not. Reflected sound is very loud if there is no absorption on the surface. Turn your speaker around to point to a wall or ceiling, and the sound doesn't change much.

Last edited by tmuikku; 27th September 2021 at 12:03 PM.
  Reply With Quote
Old 27th September 2021, 01:07 PM   #76
vineethkumar01 is offline vineethkumar01  India
diyAudio Member
 
Join Date: Aug 2019
Thanks for the awesome explanation..
Your explanation makes a lot of intuitive sense to me..
In wireless communication, we do things like beam forming and beam steering with antenna arrays. Looks like here we are doing something similar to a simplified beam steering of the crossover band of frequencies using the mid and tweeter drivers. The beam steering here is done in such a way that the perceived sound balance across frequencies and especially in the crossover band at a listening position in the far-field of these radiators is similar to the on-axis sound beam of the crossover band.

Thanks.
  Reply With Quote
Old 27th September 2021, 01:20 PM   #77
Juhazi is offline Juhazi  Finland
diyAudio Member
 
Juhazi's Avatar
 
Join Date: Mar 2007
Location: Jyväskylä
Driver spacing and crossover frequency

Tolvan Data

Click the image to open in full size.
__________________
Radikal aktivist AINOgradient speaker project
  Reply With Quote
Old 27th September 2021, 04:02 PM   #78
augerpro is offline augerpro  United States
diyAudio Member
 
Join Date: Aug 2006
vineeth> Look for MS Polymer based adhesives, or failing that, possibly simple latex. Find something with a Shore A Hardness in the low 40s. IF the datasheet doesn't list that, don't buy it. All of the silicone or polyurethane adhesives I've found cure too hard to damp vibration.

The hope is always that if CLD panels damp resonance X and CLD braces damp resonance Y, they will simply sum and you get the best of both worlds. But my concern early on was that this may not be the case, and was why I separated panel/enclosure tests from brace tests, to isolate those variables. In the end, I think the data show CLD panels plus CLD braces is the way to go on balance, but you can see that combining methods did not quite produce the results you might have predicted from the individual tests.
__________________
~Brandon
Please help my waveguide and box construction research by donating to my gofundme via my website:Soma Sonus
  Reply With Quote
Old 27th September 2021, 05:37 PM   #79
vineethkumar01 is offline vineethkumar01  India
diyAudio Member
 
Join Date: Aug 2019
@Augerpro:
Thank you.. :-)
I found this adhesive locally with datasheet specifying shore A hardness = 35-45 (https://5.imimg.com/data5/UC/JN/MY-3...-bond-ms40.pdf). From the specs would this suffice?
This will cost me 5 times less than weicon flex 310M.
  Reply With Quote
Old 27th September 2021, 06:11 PM   #80
augerpro is offline augerpro  United States
diyAudio Member
 
Join Date: Aug 2006
Yeah that looks perfect. I apply a uniform 1/32" thickness. To do this I use a fine square-tooth trowel that makes 1/16" square beads, then when I lay down a panel I push it "cross grain" to collapse those 1/16" beads into a 1/32" layer. Just like applying tile to a floor. However, I'm going to design a 3D printed trowel that will apply the 1/32" layer right from the start.
__________________
~Brandon
Please help my waveguide and box construction research by donating to my gofundme via my website:Soma Sonus
  Reply With Quote

Reply


A 3 way design studyHide this!Advertise here!
Thread Tools

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
FAST PPSL+TB W4-1320SIF design study sugestions jirm Full Range 35 23rd June 2016 10:19 PM
2.5 way, 3.5 way or 3 way Seas Centre to match my Seas 2 way front L/R's? Stewart Holmes Multi-Way 0 15th February 2014 02:51 PM
Design Study: Full Range Line Array Dumbledog Multi-Way 5 27th October 2013 12:45 PM
SU551-RS28F – a 2-way DEQX system loudspeaker measurement study gornir Multi-Way 49 11th February 2013 10:45 PM
Thermal noise study... dkemppai Everything Else 37 27th November 2002 10:54 PM


New To Site? Need Help?

All times are GMT. The time now is 01:21 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 13.64%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Copyright ©1999-2021 diyAudio
Wiki