Go Back   Home > Forums > Loudspeakers > Multi-Way
Home Forums Rules Articles Store Gallery Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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
Closed Thread
 
Thread Tools Search this Thread
Old 14th January 2010, 05:35 PM   #10721
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: cambridge ma
Quote:
Originally Posted by Steve Eddy View Post
What "fair amount of harmonic distortion," John?


se
As I pointed out to Martin Colloms at about -140-150dB hysteresis of the steel in your workbench and tools can kick in.
__________________
Pain is never permanent
 
Old 14th January 2010, 05:39 PM   #10722
Magura is offline Magura  Denmark
diyAudio Member
 
Magura's Avatar
 
Join Date: Oct 2003
Location: Denmark, Viborg
Quote:
Originally Posted by scott wurcer View Post
As I pointed out to Martin Colloms at about -140-150dB hysteresis of the steel in your workbench and tools can kick in.
So, the next logical step: An audiophile workbench.


Any takers?



Magura
__________________
Everything is possible....to do the impossible just takes a little while longer.
www.class-a-labs.com
 
Old 14th January 2010, 05:40 PM   #10723
diyAudio Member
 
Join Date: Apr 2005
Location: North Carolina
Posted by AJinFLA
Quote:
What is it about Mogami wire/cable that can't be found in the Belden catalog?
Please share some specifics.
I was about to ask the same thing, til I saw your post.
I've used plenty of Belden wire over the years. Never used Mogami.

So I went to their respective web sites. Both have propoganda and "white papers"

Belden has alot about HF signal transmission. Nada about audio. Lots of talk about newer specs for data transmission.

Mogami seems to have random meanderings about eletron theory. Didn't read it all, but some of it was kinda out there, like this quote:

"The movement of electrons is relative to how we look. If we stop and look at electrons in a wire, we see the electrons moving. But if we move at the same speed as the moving electrons, they should look static. Since their movement is not so fast, it's not an impossible task.

Now, if electrons look static from us, does that mean currents do not exist? If not, does a magnetic field exist around them? Can we say a magnetic field disappears as we move?"

I was looking for answers, but only got questions. So my answer is "no".

If current is defined by as the number of electrons passing a particular point in the conductor, how does that make any sense. Does this mean, if we and a wire are hurtling through space (on this earth) and a martian views us through his telescope, we would be electrocuted by the massive, relative current the martians percieves? Is this proof of no martians?

Should I bolt my listening chair to the floor to help aid my relative impression of the signal? My kids won't be able to listen to hip-hop oldies in their spaceship?

Not a bit of theory as to how these imaginings could audibly effect anything, even if they were true.

Sounds like someone trying to bull s**t me. Certainly doesn't look like a company I would want to do business with.

Eric
 
Old 14th January 2010, 05:44 PM   #10724
Magura is offline Magura  Denmark
diyAudio Member
 
Magura's Avatar
 
Join Date: Oct 2003
Location: Denmark, Viborg
Quote:
Originally Posted by jleaman View Post
because they are sooooo good, they have this special unique wiring braiding style with super good wire silver coated and the connectors great, i've heard responses say that they improve the bass and the sound of amplifiers

I'm looking forward to see the proof of any of the above claims.

When do you expect the AES paper with the tests and analysis is to be published for peer review ?


Magura
__________________
Everything is possible....to do the impossible just takes a little while longer.
www.class-a-labs.com
 
Old 14th January 2010, 06:01 PM   #10725
diyAudio Member
 
Join Date: Apr 2005
Location: North Carolina
This is also from Mogami's website:

"In summary, if group velocity is the propagation speed of energy and information, the special relativity theory can be disproved by using a very simple air-insulated line, but is this really the discovery of the century ?"

I'm gonna venture a "no" here, too.
 
Old 14th January 2010, 06:18 PM   #10726
diyAudio Member
 
Steve Eddy's Avatar
 
Join Date: Sep 2002
Location: Sacramento, CA
Quote:
Originally Posted by fredex View Post
So changing the wire changes nothing.
Right.

And John really needs to stop referencing his distortion measurements to imply that it does.

se
 
Old 14th January 2010, 06:18 PM   #10727
diyAudio Member
 
Join Date: Nov 2008
Location: Oakmont PA
Quote:
Originally Posted by scott wurcer View Post
As I pointed out to Martin Colloms at about -140-150dB hysteresis of the steel in your workbench and tools can kick in.
Yes, that is consistent with what I find. ( I assume your reference is 1VRMS) But it can go even higher by I suspect as much as another 20db.

A really good reason not to run your preamp signal levels at 100mv as many do.
 
Old 14th January 2010, 06:27 PM   #10728
diyAudio Member
 
Steve Eddy's Avatar
 
Join Date: Sep 2002
Location: Sacramento, CA
Quote:
Originally Posted by scott wurcer View Post
As I pointed out to Martin Colloms at about -140-150dB hysteresis of the steel in your workbench and tools can kick in.
Yeah.

Though interestingly, among the cables that were sent to Bruno was one from Dan Banquer of RE Design which was made from a steel cored coax.

I was actually expecting to see something peek up out of the grass with that one. But at -145dB, there was nothing discernible.

se
 
Old 14th January 2010, 06:31 PM   #10729
diyAudio Member
 
Join Date: Jul 2003
Location: berkeley ca
All right, everyone. You force me to explain my trials and tests for measuring cable distortion.
It all happened, maybe about 15 years ago, when I was trying to measure HIGHER ORDER HARMONIC DISTORTION to an even lower level than my test equipment was really designed to do. My ST1700B was designed to measure about -100dB or 1 part in 100,000, or .001% over most of its working range.
Measuring below that gave: NOISE and residual distortion.
However, by using an HP 3580, or 3581 with a chart recorder, I could measure lower, by removing the noise using low effective bandwidth, and I could separate the individual distortion harmonics from each other. This worked OK, but I did need to lower the residual distortion, and the input noise as well.
I modified my THD meter with AD797's in the front end to lower noise, and it indeed did it, and put an AD744 (I'm pretty sure) in the oscillator section.
In any case, I lowered the residual distortion, especially at higher orders, like 5,7,9th especially, and this is what I was actually interested in. To remove higher order harmonics even further and reduce oscillator noise, I put a passive high quality cap across the resistively buffered 600 ohm output, suggested originally by Scott Wurcer. Of course, I had to make my input and output connectors clean and tight, Cramolin worked very well for this. At this point, with a little time and effort, I could measure higher order harmonics, perhaps -20dB lower than normal or .0001%, -120dB, or one part in 1 million. This was important to me as I was interested in optimizing crossover distortion in power amps for Parasound. It took this kind of test level to do this.
Of course, to calibrate the AD1700B, I needed a cable between 1/2 and 1M long. I, then, used the most handy cable, and it seemed to work OK. Of course, for convenience I set the oscillator output from 1-3V, to lower the system noise still further.

Then, one day, wondering, because of a conversation with Dr. Vandenhul, years before, I wondered IF I would get the same results, operating at .1V or less, that is 20-40dB LOWER than normal. After all the wires worked there all the time, not at the levels I was measuring at.
I came into some real problems then. First, the equipment was not really designed to measure much below .3V. It just ran out of range and got really noisy. It was possible however, and I did so, with the help of the following Spectrum analyzer, and a lot of time, maybe 1/2 hour for one measurement.
This is when I just took a number of 1M or so cables lying around, some RS, some Monster, others, even more exotic, and made some measurements. To my surprise every cable TYPE had a different spectrum. Yet similar types had a similar spectrum, and the same cable would have the same spectrum, if returned to, later for a second measurement.
Measuring the same cables at normal test levels of 1-3V tended to remove these differences. This was a surprise, and it implied that it MIGHT be micro diodes, made with dissimilar metals and impurities in the wire that created this extra distortion. In any case, the distortion appeared, or at least the equivalent to distortion in my test equipment appeared, with regularity.
Then I tried to find differences in the wires that might make the difference, such as solder joints, or lack of them, materials, purity, insulation material, geometry, characteristic impedance, etc.
I found 2 wires that consistently measured best, but they were very different in material construction One was an Aluminum copper combination and the other was a very pure copper construction, both with a characteristic impedance of 75 ohms (as were many others).
Others, I found to create all kinds of higher order distortion, usually 6th, 7th, and 8th, was notable.
Of course, when I reported this about 10 years ago, I was hooted down by the usual bunch here and elsewhere. So there it sits. It is too difficult to run this test at this time, as my equipment is tired and needs rebuilding, so I usually say little about it anymore, because you know who will jump up and attack me, sure as the sun comes up each day. It just isn't worth it.

Last edited by john curl; 14th January 2010 at 06:38 PM.
 
Old 14th January 2010, 06:54 PM   #10730
diyAudio Member
 
tomtt's Avatar
 
Join Date: Aug 2002
Location: kansas city mo, and on occasion, around the world ...
Blog Entries: 15
Quote:
Originally Posted by john curl View Post
All right, everyone ...


did you get a chance, to measure, the Fulton Brown, or Gold?
 

Closed Thread


Hide this!Advertise here!

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
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 07:42 PM.

Page generated in 0.26432 seconds (63.84% PHP - 36.16% MySQL) with 11 queries

Copyright ©1999-2012 diyAudio