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 14th November 2011, 09:15 PM   #1
gedlee is offline gedlee  United States
diyAudio Member
 
Join Date: Dec 2004
Location: Novi, Michigan
Default Question on measuring speakers

Sorry to post this here, but most of the people who would know the answer to this come here so thats where I decided to post it. If it gets long then maybe it should be moved.

I was making some measurements today - using Holm - and I kept see glitchs at various frequencies. Now I know that I have a hum problem because you can hear it. But oddly enough, the glitches were at eaxactly 70 Hz and 280 Hz. Now this got my attention because if this were 60 Hz and 240 Hz then I'd know what it was, but it wasn't at those frequencies.

Is it possible that the AC mains are actualy at 70 Hz. temporarily? Can this every happen? I didn't think that this was possible.

Clock error in the sound card?

Any ideas how this could occur?
  Reply With Quote
Old 14th November 2011, 09:39 PM   #2
diyAudio Member
 
Join Date: Sep 2010
is it isolated to the speaker or is it the same results regardless? - Is there any possibility of issue with inductor placement/orientation/build quality?

Last edited by RockLeeEV; 14th November 2011 at 09:42 PM.
  Reply With Quote
Old 14th November 2011, 11:14 PM   #3
diyAudio Member
 
Join Date: Feb 2010
Location: in half space
I read once that power companies increase the frequency during the day to send more power down the lines when it's needed, then drop it at night to get everyone's clocks back right.


I read it on an audiophile's site, so it must be true!
  Reply With Quote
Old 15th November 2011, 12:24 AM   #4
gedlee is offline gedlee  United States
diyAudio Member
 
Join Date: Dec 2004
Location: Novi, Michigan
The thing is that there is a lot of stuff synchronous to the 60 Hz. mains. Changing it would mess all that up.

This was a fluk that pop'd up and then went away on a sample of a speaker that I have measured hundreds of times. Its not in the speaker, that I am positive of. And, its gone now. I went back to try and track it down and POOF!! All gone!
  Reply With Quote
Old 15th November 2011, 01:38 AM   #5
diyAudio Member
 
paulspencer's Avatar
 
Join Date: Sep 2003
Location: Melbourne, Australia
Earl,
For some strange reason I've found Holm to be a bit unreliable at times. It sometimes comes up with really bizarre and obviously wrong results. Press the button again and it's gone. I've never had that problem with anything else.
  Reply With Quote
Old 15th November 2011, 01:46 AM   #6
Pano is offline Pano  United States
diyAudio Moderator
 
Pano's Avatar
 
Join Date: Oct 2004
Location: Milliways
Blog Entries: 4
Ditto what Paul says. It can get glitchy for no reason. Close it and start again.
Mostly I get glitches from Windows interrupts. But they are inconsistent, but regular.
No way the mains will be a 70Hz, ever.
  Reply With Quote
Old 15th November 2011, 05:54 AM   #7
AllenB is offline AllenB  Australia
diyAudio Member
 
Join Date: Oct 2008
Quote:
Originally Posted by Keriwena View Post
I read once that power companies increase the frequency during the day to send more power down the lines when it's needed, then drop it at night to get everyone's clocks back right.
I saw this a few years ago on a documentary on power generation. (now I'm guessing they may have said 5/10/15%?)(BTW, wouldn't you guys be getting into winter?)

On the other hand mine sits quite predictably on 50Hz. My measurements remind me of a tent on a pole.

Last edited by AllenB; 15th November 2011 at 05:57 AM.
  Reply With Quote
Old 15th November 2011, 10:16 AM   #8
Helmuth is offline Helmuth  Netherlands
diyAudio Member
 
Helmuth's Avatar
 
Join Date: Oct 2008
Location: Winterswijk
Quote:
Originally Posted by paulspencer View Post
Earl,
For some strange reason I've found Holm to be a bit unreliable at times. It sometimes comes up with really bizarre and obviously wrong results. Press the button again and it's gone. I've never had that problem with anything else.
I use hbx6 and arta, and also got the strange results some times. I think it is a timing problem of hardware and software during measuring.

But you have to watch where your measurement window is with the start of the mls-impulse. That is also a source for strange results.
__________________
( (( KUGELWELLE )) )
recent projects :OB-mk1 /fatboy / monitor-xl / Horn-AM / dappolito / td124-mk1-rb301 / Hybrid-pse / Vfet

Last edited by Helmuth; 15th November 2011 at 10:18 AM.
  Reply With Quote
Old 15th November 2011, 10:30 AM   #9
just another
diyAudio Moderator
 
wintermute's Avatar
 
Join Date: Aug 2003
Location: Sydney
Blog Entries: 22
Hi Earl, do you have a CRT monitor, and if so what is the refresh rate set to? I was measuring noise on my power-supply, and had a big spike at 100Hz, funny thing was it didn't go away when I switched off the power!! After a lot of head scratching I changed the refresh rate on my monitor from 100Hz to 90Hz and the noise spike was at 90Hz. The device being measured was at least 10 feet from the monitor too!

Tony.
__________________
Any intelligence I may appear to have is purely artificial!
Some of my photos
  Reply With Quote
Old 15th November 2011, 10:47 AM   #10
Pano is offline Pano  United States
diyAudio Moderator
 
Pano's Avatar
 
Join Date: Oct 2004
Location: Milliways
Blog Entries: 4
Good thinking Tony!
FWIW, my soldering station throws out noise everywhere. I have to turn it off for good electrical measurements.
  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
Measuring speakers in-room. Practical considerations. chuyler1 Markaudio 38 2nd September 2011 08:37 PM
Measuring a speakers efficiency pjpoes Multi-Way 14 30th January 2009 03:35 PM
Need some guidance on measuring speakers mazeroth Multi-Way 4 25th January 2006 05:19 PM
Amp needed for measuring speakers with laptop JohanH Multi-Way 7 24th February 2005 06:28 PM
WTB: Mic + preamp for measuring speakers Saurav Swap Meet 2 6th October 2004 06:13 PM


New To Site? Need Help?

All times are GMT. The time now is 03:53 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