Sound Quality Vs. Measurements - Page 997 - 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 11th July 2013, 11:49 AM   #9961
qusp is offline qusp  Australia
diyAudio Member
 
qusp's Avatar
 
Join Date: Oct 2009
Location: Brisbane, Australia
Quote:
Originally Posted by fas42 View Post
Hmmm ... the second sentence in the Wikipedia article about such, Engineering - Wikipedia, the free encyclopedia, is:

If you believe the above should be exorcised from the article, feel free to do so ...
I believe there are several other aspects you are conveniently ignoring
  Reply With Quote
Old 11th July 2013, 12:14 PM   #9962
fas42 is offline fas42  Australia
diyAudio Member
 
fas42's Avatar
 
Join Date: Jun 2012
Location: NSW, Australia
Blog Entries: 11
One always discovers interesting "things" when perusing - further in that Engineering article, under Problem Solving -- Tacit knowledge - Wikipedia, the free encyclopedia ...
__________________
Frank . . . the truth is, I just like a bit of ASMR ...
  Reply With Quote
Old 11th July 2013, 12:37 PM   #9963
qusp is offline qusp  Australia
diyAudio Member
 
qusp's Avatar
 
Join Date: Oct 2009
Location: Brisbane, Australia
I wouldnt call what I do most of the time engineering ...
  Reply With Quote
Old 11th July 2013, 12:48 PM   #9964
fas42 is offline fas42  Australia
diyAudio Member
 
fas42's Avatar
 
Join Date: Jun 2012
Location: NSW, Australia
Blog Entries: 11
Yes, most people, most of the time, when they're trying to get something done,or to sort out an issue are doing this: Problem solving - Wikipedia, the free encyclopedia.

This is pretty universal, no certification or special training required ...
__________________
Frank . . . the truth is, I just like a bit of ASMR ...
  Reply With Quote
Old 11th July 2013, 12:56 PM   #9965
dvv is offline dvv  Serbia
diyAudio Member
 
Join Date: Sep 2004
Location: Belgrade, Serbia
Quote:
Originally Posted by nigel pearson View Post
And at 10 watts ?

Anyone wanting to make a modest amplifier sound better should upgrade the PSU . In theory they are wasting their time and money . In reality they are not . The simple reason I suspect is that the measurements mask the ripple . When building a budget amplifier not to have hum with no music playing is as good as it gets . With chip amps it might even be close to state of the art distortion . Theoretically as long as real life ripple current requirements are met there is no reason to go beyond 2 x 10 000 uF in most cases . Reality is that the majority wouldn't choose that . There is a strange alternative . Even smaller capacitors are possible if the majority of the amplifier is fed from a clean supply . This could be right up to the outputs . Going slightly against the grain the VAS supply being lower than the dumpers is best . This allows the dumpers to become regulators in their own right . As long as the ripple bottom isn't reached the amplifier should remain tight sounding . Ripple ratings might just be possible with 4700 uF . The big deal here is the 4700 uF especially if one notch of voltage above requirements ( 100 V running 80V ) might be a better device at HF . That is if it's role was swapped to being an output capacitor it would measure as a nicer component . Personally I see no difference in a Kirchhoff arrangement where a capacitor is the output or a PSU cap. The ultimate thing is the clean amplifier can at the flick of a switch become a dirty amp . Raise the VAS by 15 V +/- and get the best measured result for power output . Still less dirty a than typical amp where no separation is attempted ( filthy amps ) . My guess is not many will do this as capacitors fill the case , like it has 8 cylinders firing . In valve designs the CV values are low . One guy I read tried to convince us that the CV value was a square ratio . That is as voltage climbs the value of a capacitor reduces by a square . I didn't give it any thought and assumed it to be wrong . Valve designs force one to do it right . I was very upset I only got - 85 dB reference 1 watt from my SE valve amp . I learned that is not bad . DC heaters made - 2 db difference on a good day and the noise type was no better at the more audible 100/120 Hz . The CV value of the amp 170 000 at 500 V ( 4700 @ 80 V = 376000 ) . The PSU has a FET capacitance multiplier ( 50 uF ) to get the ripple required . As it is running 100 mA at 8 V loss it almost needs no heat sink .

The punch line is . Forgetting looks did we throw 100 000 uF at a problem to allow the VAS 8 mA of better power ? Down side is our ground point is less well defined ? My big amp I hear has 2 x 47 000 63 V Mundorf per channel ( it has been on holiday for a year or so in Cologne ) . It would be 100 watts 8R and will drive 2 ohms reasonably well .
Or, you can do what some of us others do, which is to split the PSU lines and use higher voltage, fully regulated input stage and VAS supples.

How many more jumps through the hoop will you do until you come to the obvious, Nige?
__________________
Per Aspera Ad Astra.
  Reply With Quote
Old 11th July 2013, 08:37 PM   #9966
a.wayne is offline a.wayne  United States
diyAudio Member
 
a.wayne's Avatar
 
Join Date: May 2008
Location: Front Row Center
Using separate supply for Input and Vas stage ....
__________________
World Cup Cat Hacky Sack given to Messi and with 30seconds to go D Germans and the rest of Europe save face ..
  Reply With Quote
Old 12th July 2013, 06:04 AM   #9967
dvv is offline dvv  Serbia
diyAudio Member
 
Join Date: Sep 2004
Location: Belgrade, Serbia
Quote:
Originally Posted by a.wayne View Post
Using separate supply for Input and Vas stage ....
Wayne, trust me, it can make a hell of a lot of difference.
__________________
Per Aspera Ad Astra.
  Reply With Quote
Old 12th July 2013, 08:29 AM   #9968
diyAudio Member
 
Join Date: Mar 2007
Location: Oxfordshire
Quote:
Originally Posted by a.wayne View Post
Using separate supply for Input and Vas stage ....

It is a cheap and obvious upgrade . Even the mighty Naim Audio failed to see it . They gave a CD player 27 supplies if I am right ?

Some guy on a Naim clone kit thread had a slightly over voltage transformer . The outputs were fine at that voltage . I showed how to put in a simple amplified Zener regulator in to make it work ( VAS +/- 40 V ) . I was very surprised to get both reservations about the idea and advice on better regulators . So from no regulator to state of the art in a few sentences . In a nutshell how things always go . The zener had the filtering cap to remove hiss . An LM317/337 would have been more problematic . I used fast power transistors . I felt a bit sad about it . Also a guy who made a monster amp who was starting to tweak it . He had slipped a couple of diodes in from output to VAS . I suggested to remove them and try a nicer PSU . Nothing said by anyone .

If you want to try something as cheaply as possible try using a capacitor input voltage doubler ( Cockcroft Walton style ) . That allows the existing PSU to be used without conflict as the capacitor prevents short circuiting . The time constants should be so that the supply is just sufficient for needs as a starting point . A very fast transistor and zener good enough to remove harmonics . Use the spectrum analyzer to look at residuals and try increasing cap size . Even 220 uF starts to work if 15 mA used . After that you now can have whatever you want . Try 10 V below , equal . 10 V above . I suspect 10 V below will be favourite . Converting the zener to capacitance multiplier is worth a thought . I recommend not to use Darlingtons . If needed a FET . Thing to realize is a 220 uF 250 V is going to be an Audiophile device even if it isn't labeled that way . The high voltage dictates that . Most high voltage caps have better tan theta . It is a byproduct of resisting flash over . If using some soft recovery diodes and a few caps it is doubtful you will exceed $15 . My hunch is it will sound like $300 invested in more PSU caps . Usually that involves serious re engineering if it is not to have increased zero volt problems ( ill defined star point , and / or bad HF zero due to thickness of metal one is forced to use ) .

This is the problem with the engineers . Douglas Self team using 10 000 uF and a 40 year old Sinclair design ( Not RCA ) . Everything analyzed and no progress made . Then the brute force engineers . Like the Dodge Viper they can not be wrong . Where are the Lotus 7 's ? NAD 3020 is as near as we got I feel .
  Reply With Quote
Old 12th July 2013, 01:35 PM   #9969
dvv is offline dvv  Serbia
diyAudio Member
 
Join Date: Sep 2004
Location: Belgrade, Serbia
You feel wrong, Nige, but the REAL problem is you're too stubborn to take a nice, long look to see why.

How many times so far have I asked you to take a look at Harman/Kardon's work from say 1985 to this day?

How many times have I sent you examples of modern schematics, only for you to come up the next day with another 40+ year old variant of your own?

You don't have to agree, you don't have to like it, you don't have to use it, but you should at least see how far SOME have gone since the days of Sinsclair.
__________________
Per Aspera Ad Astra.
  Reply With Quote
Old 12th July 2013, 01:53 PM   #9970
diyAudio Member
 
Join Date: Mar 2007
Location: Oxfordshire
My point is to breech the gap between the ones I admire most ( HK et al ) and cheap engineering .

The Sinclair brigade have been refining a reasonably good design for 43 years now . Having listened to all variants more or less the power supply stands out as the main difference . You might have guessed my day job is as a power supply designer . In my work I often have pennies to get a result . I get great job satisfaction from delivering the near impossible . When I see typical amplifiers I see the money very badly spent . I have absolutely nothing bad to say about brute force regulation and use it myself . I am convinced when it can not be used there are exciting possibility which if it entered my work I would be jumping for joy to solve . Audio designers seem to have read a religious text that says one way and one way only .

You know this makes me think . If I offered a service where any common place amp was brought to me I would do the upgrade I described . It would need a handful of components and no additional transformer . I would offer a small reduction in power with override. The formula is simple . Keep ripple bottom from signal top .
  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 08:49 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