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

Interesting read I found on Lossy Cabinet designs by Harbeth
Interesting read I found on Lossy Cabinet designs by Harbeth
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 November 2019, 01:25 AM   #221
GM is offline GM  United States
diyAudio Member
 
GM's Avatar
 
Join Date: Jun 2003
Location: Chamblee, Ga.
Art Lugwig's efforts: Loudspeaker construction

GM
__________________
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
  Reply With Quote
Old 9th November 2019, 03:40 AM   #222
bentoronto is offline bentoronto  Canada
diyAudio Member
 
Join Date: Jan 2008
Location: Toronto and Delray Beach, FL
Interesting read I found on Lossy Cabinet designs by Harbeth
Quote:
Originally Posted by PeteMcK View Post
Yes, that BBC study. I'm not sure the keenest eye could be sure they understand what they found.

My not very keen eye did notice that those rather similar FR and distortion plots are not speaker outputs. Surprised? Nooooooo. They are figure-8 mic readings of the panels with the mic nulling the driver output so as to emphasize the panel sound from nearly touching the panel.

I am amazed that the panels have such great FR and distortion - and that their various treatment experiments (that nobody can be sure quite what they were doing) made so little difference.

What's so hard about sticking a mic in front of a speaker with and without good bracing or damping and seeing if it makes much difference?

B.
__________________
HiFi aspirations since 1957. "When the toilet paper of Experience is depleted, the backside of Reason goes unwiped"
  Reply With Quote
Old 9th November 2019, 03:46 AM   #223
picowallspeaker is offline picowallspeaker  Italy
diyAudio Member
 
picowallspeaker's Avatar
 
Join Date: Apr 2007
A mic doesn't suffer from masking...
__________________
It's like learning sex during the Victorian era: you get to the wedding night and there are many things to do that you never imagined.
  Reply With Quote
Old 9th November 2019, 08:04 PM   #224
system7 is offline system7  United Kingdom
diyAudio Member
 
system7's Avatar
 
Join Date: Aug 2008
Location: Portsmouth UK
Great to see everybody taking an interest in this old Harbeth thread again.

Alan Shaw is just nuts about speakers. Great cabinets, great drivers, complex computer modelled crossovers. Harbeth was Dudley Harwood's baby originally, and Alan Shaw bought into it.

Whatever he is doing, people pay the big bucks for it, like £4,000 for a two-way and rarely complain.

The Monitor 30.1 is the classic polycone 8" bass plus metal SEAS tweeter. AFAIK, it crosses at an outrageously high 4kHz. That takes an in-house polycone 8" woofer, the Radial II, with no nasty breakups.

Click the image to open in full size.

TBH, my own enthusiasms are not from a wildly different place:

Click the image to open in full size.

Click the image to open in full size.

Happen to be made from chipboard or MDF. And, in fact, Harbeth are not averse to MDF or chipboard.

Not many people know this, but the best fighter-bomber of WW2 was the De Havilland Mosquito. Twin Rolls-Royce engines aka "drivers" and marine plywood construction. Sounds unlikely, but there it was.

Light and rigid airframe, albeit with a tendency to crack and shatter if landed heavily. Bit like his big Monitor 40 3-way loudspeaker:

Click the image to open in full size.

Most everything you need to know about lossy cabinets in one picture. The reason the front baffle is screwed on with a bit of rubber strip damping, rather than glued is the "cracked bell" idea. A cracked bell doesn't ring too well.
__________________
"Per ardua, ad astra." Best Regards from Steve in Portsmouth, UK.

Last edited by system7; 9th November 2019 at 08:16 PM.
  Reply With Quote
Old 10th November 2019, 01:17 AM   #225
critofur is offline critofur  United States
diyAudio Member
 
critofur's Avatar
 
Join Date: Jan 2004
Location: Columbus, OH
Send a message via AIM to critofur Send a message via MSN to critofur Send a message via Yahoo to critofur
Quote:
Originally Posted by bentoronto View Post
In 60 years of knocking my knuckles on every cab I met, I can't recall seeing measurements on the subject of enclosure vibration. Perhaps just my memory.

I believe all the heavy-duty opinions in this thread should await somebody showing the evidence one way or the other. Seems like a trivial experiment to measure a cab without bracing and then add the bracing.

The evidence must be out there, eh. Can't anybody post links?

BTW, used quarter-inch plywood on my 17-foot 12 Hz labyrinth. The cab does vibrate. So do the walls in my room.

B.
Talking about measuring enclosure vibration, then bringing up your bass speaker?

Cabinet stiffness helps bass response but enclosure vibrations are a higher frequency/midrange problem. People have indeed spent a *lot* of time measuring enclosure panel resonances both objectively, and, in listening tests comparing cabinet "A" to "B" to look for audible subjective differences.

Whether you like "A" or "B" better is significant and important, but, must be done in blind testing for valid results. Harmon Audio Group has an awesome speaker listening test setup.
__________________
Critofur
http://www.ohmspeakers.com <- all the folks here are my friends
  Reply With Quote
Old 10th November 2019, 02:15 AM   #226
bentoronto is offline bentoronto  Canada
diyAudio Member
 
Join Date: Jan 2008
Location: Toronto and Delray Beach, FL
Interesting read I found on Lossy Cabinet designs by Harbeth
Quote:
Originally Posted by critofur View Post
....People have indeed spent a *lot* of time measuring enclosure panel resonances both objectively, and, in listening tests comparing cabinet "A" to "B" to look for audible subjective differences
Spare us the sermon, just show the data*.

B.
* not the data on how the walls shake something awful, but the data on the speaker sound. Shaking might matter a lot, a little, or hardly at all... let's see the data.
__________________
HiFi aspirations since 1957. "When the toilet paper of Experience is depleted, the backside of Reason goes unwiped"

Last edited by bentoronto; 10th November 2019 at 02:19 AM.
  Reply With Quote
Old 10th November 2019, 07:08 PM   #227
system7 is offline system7  United Kingdom
diyAudio Member
 
system7's Avatar
 
Join Date: Aug 2008
Location: Portsmouth UK
I don't know what the heck I am talking about sometimes, but as an engineer I think that light and rigid is cheaper than heavy and floppy in responsiveness...

Consider plywood's practical application, not only to speaker cabinets, or WW2 fighter-bombers. I'd always trust beautiful aesthetics to the Italians. They grow up with this stuff all around them.

Not many people know this, but the best speedboat in the World is the Italian Riva Aquarama. Built of plywood with all the crossbracing that boats need when buffeted by waves. Twin Lamborghini engines, the aquatic equivalent of Scanspeak. A thing of great beauty.

Perhaps there are two schools of thought on this. Maybe Carbon-fibre is a good modern light and rigid material for the outer frame. Maybe nature has evolved near-perfect wood for its trees which must survive heavy stress in windy winters. See, wood must bend, wood must be strong.

I do notice that a "Retro" Stealth Bomber might as well be made of plywood. But, TBH, I can't design a wooden engine to keep it off the radar screen...

Maybe the Lamborghini V12 was a worthy derivative of the Rolls Royce Merlin V12.

Light and fast is the predator approach. Slow and heavy is their Prey! How it works. And we know who generally wins.
__________________
"Per ardua, ad astra." Best Regards from Steve in Portsmouth, UK.
  Reply With Quote
Old 10th November 2019, 07:48 PM   #228
Galu is online now Galu  Scotland
diyAudio Member
 
Join Date: Apr 2018
Quote:
Originally Posted by system7 View Post
Light and fast is the predator approach. Slow and heavy is their Prey! How it works. And we know who generally wins.
Generally, it's the latter - I've been watching David Attenburgh!
  Reply With Quote
Old 10th November 2019, 08:11 PM   #229
Robbintip is online now Robbintip  Netherlands
diyAudio Member
 
Join Date: Nov 2012
Location: Amsterdam
Riva Blue is perhaps one of the nicest colors I ever saw on a car (or boat, for that matter), my monitor doesn't do it any justice. I remember seeing some Lamborghini-engined boat on topgear?, might have been a Riva? It had one of the V12's engineered to invert it's rotation, counteracting centrifugal forces acting on the mass of the boat.

Some questions arise..
At which point (stiffnes) would you consider speaker cabinet walls as another effective mass (spring mass system) and worth the time tuning its properties considering its non-linear stiffness coefficient?

For higher frequency duty, do the walls need to have highly conductive properties? Is inner damping even wanted?:

It is perhaps possible to tune the side walls of a cabinet in a way, that it radiates sound waves to cancel/smoothen diffraction patterns radiated by the front baffle edges? Would something like that function at all, accoustically speaking, and if it does: would side mounted drivers be a more efficiŽnt approuch for someone as simple minded as me?
__________________
Sub: 16x Peerless XXLS P835037 (8-80Hz) awaiting Motional Feedback, Fronts: Satori WO24P-4 (80-200Hz), Satori MW16P-4 (200-1780Hz), SB26ADC (1780Hz-20kHz)
  Reply With Quote
Old 10th November 2019, 08:48 PM   #230
Galu is online now Galu  Scotland
diyAudio Member
 
Join Date: Apr 2018
The general public have become so accustomed to hearing the box resonances that are present in the the majority of affordable commercial loudspeakers that they regard the sound they produce as normal.

Although open baffle speakers may be regarded by the majority as being lightweight in bass reproduction, their aficionados would describe box speakers as sounding blurry and coloured by comparison.
  Reply With Quote

Reply


Interesting read I found on Lossy Cabinet designs by HarbethHide 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
TA2024 found a new home (read: case) maurycy Class D 5 9th April 2014 10:33 AM
Interesting Read On 300B's Trout Tubes / Valves 7 26th March 2005 02:47 AM
found an interesting read kaukasion Solid State 0 31st October 2003 12:57 AM


New To Site? Need Help?

All times are GMT. The time now is 11:21 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki