What really matters? Quality loudspeaker design. - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way

Multi-Way Conventional loudspeakers with crossovers

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 3rd November 2007, 08:59 PM   #1
Rounder is offline Rounder  Canada
diyAudio Member
 
Join Date: Jan 2006
Location: ONTARIO CANADA
Default What really matters? Quality loudspeaker design.

I have spent 1000's of hours researching loudspeaker design and as a result when i got to design my own 2way I come across many sacrifices which must be made. Yes i know loudspeaker design is a game of tradeoffs. My question is what has the most value in creating good sound. In other words what qualities should i attempt to incorporate into my design. Please do your best in ranking the following in order of importance based on your experience and knowledge and feel free to include any comments explaining yuor decision or the affect of the attribute.

1. First order crossover for phase correct design
2. Time aligned drivers as a result of baffle design.
3. Narrow baffle to increase imaging and reduce diffraction.
4. Open air tweeter design where the tweeter sits on top of a front baffle to avoid reflections.
5. Very rigid box with thick front baffles, sand loaded bases and extensive bracing.
6. Offset tweeter for smooth response.
7. Low group delay (below what time at what frequency)
8. Proper damping/stuffing. Where and how much.
9. Rounded baffle for smoother response.
10. Flush mounted drivers.
11. Close distance between drivers.
12. Dampened cabinet walls.


I know theres lots im missing so feel free to add.
__________________
The bitterness of poor quality is remembered long after the sweetness of low prices is forgotten.
  Reply With Quote
Old 3rd November 2007, 09:20 PM   #2
diyAudio Member
 
Join Date: Mar 2007
Location: Canandaigua, NY USA
I think good speakers have been made that break almost all the rules, though not at the same time! My #1:

1) Quality drivers with the desired response and no breakup or misbehavior well beyond the crossover points.

I've never been able to turn a bad driver into a good driver with any amount of eq, zobels, or other electrical magic, and there are an awful lot of bad drivers out there. It would seem that the market for buzzers and sirens is larger than I would have predicted.
  Reply With Quote
Old 3rd November 2007, 10:29 PM   #3
diyAudio Member
 
Join Date: May 2004
Location: San Francisco
Send a message via AIM to joe carrow
Default Re: What really matters? Quality loudspeaker design.

I don't think ranking is really possible because engineering is all about trading good for bad to reach a happy medium, and many things interact- and not many folks can agree what makes one speaker better than another, and often even if one speaker IS better than another.

Here are a few of my comments on your criteria.

1. First order crossover for phase correct design

Really not that important. I'm listening to some beautiful sounding drivers with a really steep filter, and I honestly can't hear the phase.

2. Time aligned drivers as a result of baffle design.

This is helpful, but can be overcome somewhat in crossover design.

3. Narrow baffle to increase imaging and reduce diffraction.

Some will argue that "the best baffle is no baffle"- as in, building an infinite baffle to flush mound the speakers on a wall. I think that the most practical thing to do is to simulate the effect of the baffle, and lay out your drivers accordingly- then perhaps use some felt to absorb some of those high frequencies as the spread out over the cabinet face.

4. Open air tweeter design where the tweeter sits on top of a front baffle to avoid reflections.

I think that managed directivity is very important, and I'm not sure that this approach serves this goal. In the case of Linkwitz's Pluto speaker, he did something like this with the tweeter, but the very low crossover frequency allowed the entire collective speaker to stay nearly ominidirectional across the entire crossover.

5. Very rigid box with thick front baffles, sand loaded bases and extensive bracing.

Sand loaded bases seem like a waste of time to me. Overly thick front panels can cause weird cavity resonances in the area between the back of the woofer cone and the main body of the box. Rigid boxes are good, bracing is good, and even better is the rule of thumb that you build stiff for bass and build heavy for mids/highs. The key is that your cabinet can ring like a bell, as long as its fundamental frequency is never excited by the driver or any of its harmonics. Separate cabinets to divide up the frequencies strikes me as a great idea for this, as it also cuts down on the weight of the largest piece you'll have to move.

6. Offset tweeter for smooth response.

Again, this is something that needs to be measured and simulated. A centered tweeter has an effect, but other things might have effects that cause this to be desirable, or at least less objectionable.

7. Low group delay (below what time at what frequency)

There have been some good articles written on this if you google around for them. If memory serves, most mid/high crossovers don't suffer from perceptible group delay. The main area of controversy that I keep hearing about is woofer to sub crossovers.

8. Proper damping/stuffing. Where and how much.

Trial and error- it's different for every speaker. An open baffle speaker doesn't need any. Ported boxes are a touchy thing, and it's best to avoid stuffing lest you damp out the desired port response.

9. Rounded baffle for smoother response.

Eh, depends- you can simulate and/or measure the consequences. You can compare it to chamfered edges. You can consider just covering the face with heavy felt.

10. Flush mounted drivers.

Overall, this looks to be fairly important. This is also something that is measured easily enough, and if flush mounting was really not an option, something that could be accounted for in a crossover.

11. Close distance between drivers.

Yes, looking at the wavelength of sound at the crossover frequency will tell you how close they need to be. Within 1/16th wavelength at crossover is about as good as it gets, greater than 1/2 wavelength is seriously getting in trouble.

12. Dampened cabinet walls.

I've said it before, I'll say it again- "dampen" means "to make moist", as in- with water. Do you mean that the walls have mechanical damping so that resonance in the wall panel is dissipated quickly? This is important if you're forced to leave a panel resonance in or near the bandwidth of the driver in that cabinet. If you mean acoustic absorbing material like foam or fiberglass, yes- this is important too.

That's just my two cents. There are still a lot of myths out there, and a lot of things that get repeated without real understanding. I'm not a guru or anything, but I try to know what I think I know.
  Reply With Quote
Old 3rd November 2007, 11:40 PM   #4
diyAudio Member
 
sdclc126's Avatar
 
Join Date: Jan 2005
Location: San Diego, CA
First on your list should be driver selection! The lowest distorting drivers sound the best because they change the input signal the least.

www.zaphaudio.com
__________________
Soft Dome
  Reply With Quote
Old 3rd November 2007, 11:59 PM   #5
diyAudio Member
 
Join Date: Nov 2005
Default Re: What really matters? Quality loudspeaker design.



Use good xo components. They can only be judged accurately after breakin unfortunately. Wire with good wire, and a star ground is recommended. I prefer drivers with clean cumulative spectral display (waterfall) graphs. Be wary of differing scales when comparing. I like to see at least a 30 dB vertical scale. For me, CSD is the best correlation to sound. I REALLY prefer a mid driver with a smooth high end rolloff. I prefer a trap (if necessary) to a steeper rolloff filter design.
  Reply With Quote
Old 4th November 2007, 12:13 AM   #6
diyAudio Member
 
Join Date: Dec 2005
Location: Sao Paulo
Send a message via MSN to -_nando-_ Send a message via Skype™ to -_nando-_
First of all --> Choose the correct transducers

Second --> Match them, make the right frequency cut (DIFFICULT!) and attenuation.

Third --> Have a good cabinet, foam inside, thick wood, good air duct calculated considering phase, impedance, and frequency response.

Fourth --> Well aligned transducers.

In my opinion, 3 way systems are BETTER.

In 2 way systems, the mid frequencies reproduction are critical, due to the cone moviment caused by the lower ones, resulting in mid distortion.

I would go with a 3 way design, and cut the first woofer about 120Hz.

Then you can use a nice mid woofer and the tweeter selection is less critical as the mid woofer can go higher than it would go in a 2 way design. You can choose then a more cheap, light and smooth tweeter.
  Reply With Quote
Old 4th November 2007, 12:15 AM   #7
diyAudio Moderator
 
pinkmouse's Avatar
 
Join Date: Apr 2002
Location: Chatham, England
Hi Rounder, I don't want to sound too negative, as you have obviously been thinking about this a lot, but all your list items are what I would call secondary considerations that can be addressed much later in the design process.

First things first, define the size of box you, (or your significant other), can live with. Then, find a low distortion mid bass driver with a good FR you like and work out the optimal design, (TL, BR, IB, aperiodic), to get where you want. Then look at tweeters to suit the high end roll off of your mid bass. Once you have suitable candidates, build a test box and measure. Then you can start worrying about crossover type, speaker positioning, etc, listening and measuring as you go.
__________________
Rick: Oh Cliff / Sometimes it must be difficult not to feel as if / You really are a cliff / when fascists keep trying to push you over it! / Are they the lemmings / Or are you, Cliff? / Or are you Cliff?
  Reply With Quote
Old 4th November 2007, 12:21 AM   #8
fpara is offline fpara  Canada
diyAudio Member
 
Join Date: Nov 2005
Indeed, the bass/size/boxtype issue is often the first (and decisive) concern to address.
  Reply With Quote
Old 4th November 2007, 12:23 AM   #9
Rounder is offline Rounder  Canada
diyAudio Member
 
Join Date: Jan 2006
Location: ONTARIO CANADA
thanks for everyones input.

Considering how this topic is starting to focus a little more on my personal design ill mention that the parts that i am working with are the peerless hds tweeter 810921 and the hds 6.5 exclusive peerless woofer 830883. Most likely a small tower with roughly .7cuft and an 8 inch wide front baffle. I havent decided anything for sure other than drivers which i have purchased... i would like to use a first order crossover if i can make it sound good... i was thinking roughly 1500hz on the woofer and1800hz on the tweeter... with a notch on the woofer to take care of the peak. I like a bit of a bass kick so ill probably tune it for a bit of a bump at 50hz or so.
__________________
The bitterness of poor quality is remembered long after the sweetness of low prices is forgotten.
  Reply With Quote
Old 4th November 2007, 01:28 AM   #10
Nanook is offline Nanook  Canada
diyAudio Member
 
Nanook's Avatar
 
Join Date: Feb 2004
Location: Chinook Country.Alberta
Default rounder ....come over to the dark side

and give up on all that stuff.Here's my take on importance in design...(tongue in cheek towards the other suggestions, but this has worked for me...)

  • room setup, but you CAN make a pretty crumby room sound better , as long as the SOAF is high
  • no enclosures...just a baffle.
  • no crossovers
  • single driver
  • Quad ESL , Wharfedale SB3 sized baffles (as in the JE Labs "style)

Based on your biases, the OB way is definetly not the way to go, but I had to state it...

really, it is all personal. And there are good/great DIY versions of all types. with crossovers, keep the X-over points at least a full octave away from the resonant frequencies of each driver/tweeter pair that you are considering. And all Xovers create some phase/group delays. Another option may be to do as Linkwitz and others do and use an active crossover and bi-amp your speakers...

and you have not listed your amplification, room size and musical tastes. They are all important.
__________________
stew -"A sane man in an insane world appears insane."
  Reply With Quote

Reply


Hide 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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
which loudspeaker design? maghen Multi-Way 128 2nd October 2009 09:10 PM
Philoctetes: Why Audio Quality Matters - very interesting video ShinOBIWAN Multi-Way 75 6th January 2009 10:01 PM
Loudspeaker Quality Measurement dm1179 Multi-Way 1 14th June 2007 07:57 AM
What is E5 in The Loudspeaker design cookbook? kimbo Multi-Way 8 31st January 2005 12:11 PM
Loudspeaker construction vs sound quality josefr Multi-Way 4 11th April 2003 06:24 AM


New To Site? Need Help?

All times are GMT. The time now is 11:26 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2