Beyond the Ariel - Page 218 - 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 22nd September 2007, 11:17 PM   #2171
terry j is offline terry j  Australia
diyAudio Member
 
Join Date: Aug 2006
Quote:
Originally posted by Lynn Olson

There. Four listening techniques that will reveal a great deal of the gross and obvious defects of speakers from $100 to $100,000.

[/B]

Absolute gold.



Thankyou Lynn.
  Reply With Quote
Old 22nd September 2007, 11:43 PM   #2172
diyAudio Member
 
Graham Maynard's Avatar
 
Join Date: Dec 2003
Location: UK
Hi Lynn,

Yes, sticking your head inside a cabinet to listen reveals many different sounds with all sorts of unexpected peaks reverberating between the walls. I have noted they seem to change in tonality, becoming more intense at mid frequencies with increasing levels of reproduction, whereas hearing variation with level would be more sensitive to bass and treble with increasing level.

I wonder if these 'interferences' all relate to the cabinet itself, or whether there can be changes due to air motion over internal boundaries and edges, also around the likes of TL cabinet foldings. Maybe it is just the bass pressures increasing cabinet ringing.

And what you say about running the tweeter on its own; this can also reveal amplifier weaknesses, say in some lesser SS types and especially when these are compared to tube.

Cheers ........... Graham.
  Reply With Quote
Old 22nd September 2007, 11:49 PM   #2173
DDF is offline DDF  Canada
diyAudio Member
 
DDF's Avatar
 
Join Date: Sep 2004
Location: Ottawa
My favorite tests for box noise is to place the speaker in a dead, large or outdoor environment and then run an MLS signal, or white noise. Kill it instantaneously and listen for the "boing" that trails the end of the signal, leading to silence. 90% of venteds make nice flower pots after this test.
  Reply With Quote
Old 23rd September 2007, 12:50 AM   #2174
diyAudio Member
 
Lynn Olson's Avatar
 
Join Date: Jul 2004
Location: Northern Colorado
My friend John Atwood (former technical editor of Vacuum Tube Valley and of day jobs at Intel, Sequent, and Apple) likes to speak of the "example proof". Here's some are some examples:

There were some interesting theoretical advantages for transformer coupling in a Class A PP triode amplifier - Norm Crowhurst just barely hinted at it, and there were some interesting amplifier of the Thirties that used this method. I was intrigued and curious. Rather than follow the example of mid-Nineties SET enthusiasts - who were only interested in RC-coupled SETs, I decided to find out for myself when I designed my first amplifier. Zero support from Arthur Loesch, the NY Triode mafia guys, anyone in Oregon, all of whom thought I was nuts and at the least, wasting my time. "Everybody knows" that PP is no good at low levels, it takes a SET to get the First Watt right, blah blah blah.

Well, theory informed me that Class A PP with DHT triodes would have the lowest distortion at all levels, and Western Electric was unlikely to have chosen this topology for their most advanced 300B amplifier without a good technical reason. Further research turned up significant advantages for transformer coupling (in a non-feedback amplifier) - precisely symmetric drive for both grids under dynamic conditions, no RC-coupled "blocking" when grid current was drawn, driver distortion reduced by severalfold, and instantaneous recovery from overload. Not small advantages.

Well, when the Amity was completed, surprise surprise. It didn't sound anything like a conventional PP amplifier, nor did it sound like a SET, either. And the intrinsic distortion, with no feedback anywhere, measured lower than a SET or a conventional PP amplifier (when the loop was opened). In fact, it had lower distortion with zero feedback than a conventional Williamson or Dyna has with 20 dB of feedback!

This is an example proof. Investigate the theory, build, measure, and listen. Ignore the fashion crowd who don't have the courage to think, build, and listen for themselves. All they do is consume, and hide behind the opinions of others.

Dr. Geddes had the courage to go outside existing horn theory, develop his own theories, model them, build, measure, and listen. That's an example proof. It carries a lot more weight than any opinion on the Internet or in a magazine.

But there's a difference. Dr. Geddes is using the more rigorous Floyd Toole protocol of a double-blind listening panel to determine which acoustic parameters to optimize, and which to give less weight. I'm more like an artisan, using theory, building, measuring, and listening for my own pleasure, not the satisfaction of a listening panel. We're using similar tools, but our goals are different.

I think you can see by now why I give so little weight to anything I haven't personally auditioned, especially if there are no measurements available. As an artisan, I look for examples that sound "beautiful" - the Quad ESL57, Siegfried Linkwitz's speakers, and the Bastanis Apollo - and discover what they have in common, and the underlying design theories. If the designer is still around, so much the better, since much of the more interesting theory & practice is never written down or published. You have to meet the designers in person to find out what they really think - or if they hired somebody else to do the job.

So if some guy in Boston thinks "dipoles are for primitive tastes", so what? There are three well-known example proofs that point in the other direction. I've listened to all of them at considerable length, and don't need anyone to dictate their tastes to me. If you see yourself as an artisan, cultivate your own tastes, and learn the methodologies from others.
  Reply With Quote
Old 23rd September 2007, 01:15 AM   #2175
diyAudio Member
 
Lynn Olson's Avatar
 
Join Date: Jul 2004
Location: Northern Colorado
Quote:
Originally posted by DDF
My favorite tests for box noise is to place the speaker in a dead, large or outdoor environment and then run an MLS signal, or white noise. Kill it instantaneously and listen for the "boing" that trails the end of the signal, leading to silence. 90% of venteds make nice flower pots after this test.
True. This is a variation of the 1950's BBC chopped-sinewave technique for finding what D.E.L. Shorter called "buried resonance". Back then, they used a scope with a delayed trigger to see what interesting things happened when the sinewave was suddenly cut off - they'd slowly sweep the driver and look for high-Q "tails" on the scope.

Nowadays, we use a digital CSD to see the same thing. But interrupted-transient methods tell us a lot in a short time, both by direct audition and measurement. Direct audition of clicks, interrupted noise, steady-state noise, and broad-spectrum music (not jazz or pop music) tell us a lot when we listen for "multiple personality" dispersion and box & driver colorations. Sitting in a chair and trying to impress other audiophiles with your listening skills tells you very little.
  Reply With Quote
Old 23rd September 2007, 01:37 AM   #2176
diyAudio Member
 
Join Date: Jan 2004
Location: Washington State
Default Rattles

Guys/Lynn ...
My favourite speaker test uses this free little jewel http://www.audiotester.de/ easily hooked up to your system. It will do wonders. Frequency steps are 1/100th. Do not use an alternate sound source as you need the exact interaction between your room/house and your system. Or, even within the speaker system itself. I use an old stethoscope (the heart ones are better as they have a deep frequency side) for the speakers themselves.
You can find rattles and resonances you just thought you corrected. Sine waves may not be best. Others/Lynn should have a better grasp on that end.
It's not the rattles per say that gets you, it's the feedback it causes at the speakers.
So if you find the plaster board is rattling (that be me with old 1/2" sheet rock), that's not a real problem, either. You'll probably be painting anyway, someday. Hit the board with sheetrock screws. Stud finder <$20. There are wires in the walls. Check with contractor as to what length screws to use. Fill holes and repaint. It's not a big deal unless you make it so. Just do a little at a time. One wall in a weekend shouldn't kill almost anyone.

I love it, almost like an Easter Egg hunt. BTW, after you go thru the first round, change the volume and do again. Funner than you might think. Hell, get the Wif and kids to help.
For large items like a glass china cabinet that cannot be cured, just throw it out. Me, divorced? How did you know?

Hardware to correct problems? Minimal in most cases, system improvement, priceless.
Zene
  Reply With Quote
Old 23rd September 2007, 02:13 AM   #2177
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
- For listening around a speaker, I must add that FR bipoles are good at it too. For anyone not familiar with FR bipoles, Planet 10 DIY audio moderator is the master bipole main man for anyone interested further. He has a site and many posts. I have made some too, and a small one, the ''TB3 Revisited'' got built by American and European members here, and it has even been used with a Hiraga Amp by a Dutch member.

- For listening in a box, I want to add a simple technique I use when choosing stuffing. I put my head and talk in to the box. Every time my voice sounds the best I can achieve by changing type and arranging the stuffing, so it does the mid bass of the final speaker.
  Reply With Quote
Old 23rd September 2007, 07:42 AM   #2178
diyAudio Member
 
Join Date: Aug 2006
Quote:
Originally posted by Lynn Olson

There. Four listening techniques that will reveal a great deal of the gross and obvious defects of speakers from $100 to $100,000.
  Reply With Quote
Old 23rd September 2007, 07:52 AM   #2179
diyAudio Member
 
Graham Maynard's Avatar
 
Join Date: Dec 2003
Location: UK
I found a quick way of listening to the 'sound' of a LS enclosure is to tape a few layers of newspaper over a driver opening and tap it firmly - you hear the cabinet 'tone' without driver influence or filtering.

The sound is also very similar to what you hear when you tap the cone of an electrically disconnected driver in the cabinet, and it shows how you can hear much more from the cabinet via the driver than from the driver itself.

A good driver connected to a competent NFB amplifier with short or low resistance cables does not resonate similarly at the lower frequencies due to amp/driver damping, but it does not take much in the way of crossover inductor, cable length or even a short length of inadequate cable for the enclosure 'tones' to start becoming audible during music reproduction.

(Some of the older commercial 'Hi-Fi' LS used woefully thin internal interconnects)
(I think I have just presented a case for driver sited plate amps at LF.)

Cheers .......... Graham.
  Reply With Quote
Old 23rd September 2007, 08:08 AM   #2180
soongsc is offline soongsc  Taiwan
diyAudio Member
 
soongsc's Avatar
 
Join Date: Mar 2005
Location: Taiwan
Quote:
Originally posted by Lynn Olson
...
There. Four listening techniques that will reveal a great deal of the gross and obvious defects of speakers from $100 to $100,000.

__________________
Hear the real thing!
  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



New To Site? Need Help?

All times are GMT. The time now is 07:09 AM.


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