Sound Quality Vs. Measurements - Page 268 - diyAudio
Go Back   Home > Forums > Member Areas > The Lounge

The Lounge A place to talk about almost anything but politics and religion.

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 21st February 2012, 08:53 PM   #2671
tvrgeek is offline tvrgeek  United States
diyAudio Member
 
Join Date: Dec 2009
Location: Md
Quote:
Originally Posted by dvv View Post
Completely agreed.

It's just that my own taste runs into the bipolar group, as MOSFETs don't do it for me either. Although I am always open to new experiences. You never know, and I have had a few surprises in my time, and in both directions.
I was a MOSFET output fan until recently when I moved to JBT output amps of high enough quality. (Rotel and Parasound) I don't miss the "mist" or weak bass. (Sony, Sanyo, B&K, Haflers).
  Reply With Quote
Old 21st February 2012, 08:56 PM   #2672
tvrgeek is offline tvrgeek  United States
diyAudio Member
 
Join Date: Dec 2009
Location: Md
I would have to agree that I would like to see distortion numbers at 1W as well as rated. While we are at it, how about a waterfall plot?
  Reply With Quote
Old 21st February 2012, 09:03 PM   #2673
bcarso is offline bcarso  United States
diyAudio Member
 
Join Date: May 2005
Location: Canoga Park, California
Quote:
Originally Posted by tvrgeek View Post
[snip] While we are at it, how about a waterfall plot?
Won't that throw up more mist? Or at least make things etwas feucht? (apologies Dennis!)
  Reply With Quote
Old 21st February 2012, 10:24 PM   #2674
tvrgeek is offline tvrgeek  United States
diyAudio Member
 
Join Date: Dec 2009
Location: Md
Only by a small factor.
  Reply With Quote
Old 22nd February 2012, 06:41 AM   #2675
dvv is offline dvv  Serbia
diyAudio Member
 
Join Date: Sep 2004
Location: Belgrade, Serbia
Quote:
Originally Posted by tvrgeek View Post
I would have to agree that I would like to see distortion numbers at 1W as well as rated. While we are at it, how about a waterfall plot?
Sure, no problemo, just subscribe to Italy's "Suono" magazine, they have had it for over 20 years now.

And it can show up things. They once had a test of power amps, like 14-15 years ago. In it they had offerings from Harman/Kardon, Sony, Nakamichi and, to the point, Musical Fidelity. Well, H/Ks was absolutely clean up until about +1 dB, Sony's was good to 0 dB, Nakamichi's started to deteriorate at about +1.2 dB, while the Musical Fidelity's, the small model touted as Class A (which it really wasn't, it ran in class A until about 14 of its nominal 30 W/8 Ohms or so, so it was really a High Bias product), was a mess all around. The thing was running wild from about -5 dB upwards.
  Reply With Quote
Old 22nd February 2012, 12:10 PM   #2676
a.wayne is offline a.wayne  United States
Sin Bin
 
Join Date: May 2008
Location: Front Row Center
What about the power cube test , i don't see it being used anymore ......
  Reply With Quote
Old 22nd February 2012, 12:19 PM   #2677
dvv is offline dvv  Serbia
diyAudio Member
 
Join Date: Sep 2004
Location: Belgrade, Serbia
Quote:
Originally Posted by a.wayne View Post
What about the power cube test , i don't see it being used anymore ......
Not sure what that is?
  Reply With Quote
Old 22nd February 2012, 02:27 PM   #2678
BFNY is offline BFNY  United States
diyAudio Member
 
Join Date: May 2004
Location: Saratoga NY
What about the low frequency cut-off, and what value it needs to be?

I run into this one with FM tuners, where you need flatness to at least 3Hz on the detector out composite signal to get full stereo separation from the MPX decoder.

Also, though you can have a system where individual components have decent low frequency cut-off, when you put all the components in series, you create a bunch of serial low low pass filters. Then that "system" has a total low pass characteristic that's the sum of the components, (and cables used). This can be different for everyone, depending on how things "match". And this does not even yet include the speakers, but then yes, they have their own low pass cutoff.

And what is the music requirement for low frequency cutoff? Don't think about sine waves, think about transients. What is the relationship between the width of a transient and frequency content?

And when you roll off the low end, what does that do to the phase response, and can anyone hear the phase of, say, an 80Hz signal's harmonics?

I ask because I've read that many designer's feel there is a "sweet spot" for low end roll-off that "sounds good".
  Reply With Quote
Old 22nd February 2012, 02:46 PM   #2679
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
Quote:
What is the relationship between the width of a transient and frequency content?
Roughly, the wider the 'transient', the lower the lowest frequency content. For a single unrepeated transient the frequency content goes down to DC, but that does not necessarily mean that the audio system has to go down to DC. We perceive very low air frequency air movements as a draught rather than sound.

You are right to say that LF cutoffs accumulate. Cables don't have an LF cutoff; they go down to DC. Rolling off the LF is necessary with any realistic speakers. My guess is that, apart from the special case of stereo decoders, the main need is to maintain channel balance on LF phase rather than worrying too much about the actual value. Having said that, you can reckon that there is a significant phase change up to about a decade in frequency either side of the -3dB point.

The 20Hz LF cutoff often quoted is not too daft, when you realise that the lowest note in music is 17Hz (?) and many speakers rolloff quickly below about 40-60Hz. Then there is the need to balance LF and HF cutoff, so the product of the two is in the right region. There was a thread about this last year.
  Reply With Quote
Old 22nd February 2012, 04:37 PM   #2680
bcarso is offline bcarso  United States
diyAudio Member
 
Join Date: May 2005
Location: Canoga Park, California
Quote:
Originally Posted by dvv View Post
Not sure what that is?
AudioGraph Power Cube - Stand Alone System

I brought this up with Floyd Toole a couple of days ago (having asked Martin Zanfino, now with Infinite Algorithms and formerly VP Engineering with Harman Kardon, what was that 2-d representation of a 3-d plot with different loads that showed how close to perfect voltage sources power amps were?), and he dug a bit and found the audiograph site. I love their water-cooled model

Marty remarked that when h/k started to characterize their and others' amps using their own version of the power cube, audiophiles remarked that it was one of the first measurements that seemed to correlate with perceived sound quality. The h/k amps were designed by Ritchie Miller, who according to Marty is still active although formally retired, and they emphasized high current capability as well as wide bandwidth.


Brad
  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
Quality Control differences = variations in sound quality? KT Class D 3 4th June 2014 12:02 AM
Sound Card for Measurements Marik Solid State 2 2nd January 2012 08:59 PM
Sound Card Recommendations (For Audio Measurements) dchisholm Equipment & Tools 5 16th July 2011 09:40 AM
How to protect sound card during amp measurements? okapi Everything Else 13 2nd September 2008 03:06 PM
Sound cards - test and measurements jackinnj Everything Else 2 5th July 2003 03:02 PM


New To Site? Need Help?

All times are GMT. The time now is 04:56 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