John Curl's Blowtorch preamplifier part II - Page 2455 - 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 15th July 2012, 04:47 PM   #24541
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: cambridge ma
Quote:
Originally Posted by BV View Post
Zanden 5000 review.
Wow! I go for the 6moons reviews of this stuff, the total copper alone must cost $100's.

As usual they start right in confusing anti-imaging with anti-aliasing, but we know what they mean.

I mis-spoke slightly before, in a capacitor the displacement curent and voltage go hand in hand (I = CdV/dT) so in fact you can look at it either way, still no dV/dT no I. In my example the distorted portion of displacement current in the .1u goes through the parallel combination of .1u and 1u and hence the voltage manifestation of the distortion is attenuated (with 10,000uF VERY attenuated). We soon arrive at one of Ed's examples of -140dB distortion mattering.
__________________
Silence is so accurate.

Last edited by scott wurcer; 15th July 2012 at 05:11 PM.
  Reply With Quote
Old 15th July 2012, 04:58 PM   #24542
gpapag is online now gpapag  Greece
diyAudio Member
 
gpapag's Avatar
 
Join Date: Nov 2002
Location: Athens-Greece
I had to look again.
It was John Watkinson and not John Atkinson the author of the excellent book "The Art of Sound Reproduction"

Amazon.com: The Art of Sound Reproduction (9780240515120): John Watkinson: Books

George
__________________
["Second Law is a bitch." - SY] ["The Road To Heaven:Specify the performance & accept the design. The Road To Hell:Specify the design & accept the performance"-Bruno Putzeys]
  Reply With Quote
Old 15th July 2012, 05:49 PM   #24543
1audio is offline 1audio  United States
diyAudio Member
 
Join Date: Mar 2004
Location: SF Bay Area
Blog Entries: 3
Quote:
Originally Posted by scott wurcer View Post
Wow! I go for the 6moons reviews of this stuff, the total copper alone must cost $100's.

As usual they start right in confusing anti-imaging with anti-aliasing, but we know what they mean.

I mis-spoke slightly before, in a capacitor the displacement curent and voltage go hand in hand (I = CdV/dT) so in fact you can look at it either way, still no dV/dT no I. In my example the distorted portion of displacement current in the .1u goes through the parallel combination of .1u and 1u and hence the voltage manifestation of the distortion is attenuated (with 10,000uF VERY attenuated). We soon arrive at one of Ed's examples of -140dB distortion mattering.
Very quickly the ESR and its linearity dominates in this example. If your source is 160 Ohm and the esr is 50 milliOhms you have an attenuation of around 80 dB. At higher harmonics the esl will dominate and they will increase in level. Perversely, this is where surface mount multilayer ceramics excel (if they aren't generating stuff). And at high frequencies the PSRR of the circuit deteriorates. A large film cap will have much higher inductance and may cause problems if very fast transistors are used with less than the most sophisticated layouts. Introduce digital circuits and a desire to meet FCC and you may have no alternative to the surface mount MLCC's.
__________________
Demian Martin
Product Design Services
  Reply With Quote
Old 15th July 2012, 06:11 PM   #24544
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
I am glad you Scott clarified your statement, and I read this discussion to the end of the last page. Now we can clearly see that sources of distortions can be caused by either non-linearities of capacitors (in case of high DA it can be non-linear ESR as Demian pointed out), or non-linearities of stages that the cap couples. No miracles found.
__________________
"Our youth [...] have bad manners, contempt for authority; they show disrespect for their elders, contradict their parents, [...] and tyrannize their teachers. -- Plato, 447-367 BCE
  Reply With Quote
Old 15th July 2012, 06:42 PM   #24545
bcarso is offline bcarso  United States
diyAudio Member
 
Join Date: May 2005
Location: Canoga Park, California
For additional perversity note that some circuits, e.g., notoriously, low-dropout voltage regulators, have a propensity to oscillate when the output capacitor is too good, i.e., low ESR. So having a lossy part there can work better than a low-loss one. For perhaps better control of the situation one may wish to add some lumped series resistance with the lower-loss capacitors. But of course this does set a lower limit to the amount of attenuation of load current modulation.

Many years ago, I attended a seminar about a new processor chip developed by DEC (remember them?) and although most of the material was far afield from my interests then and now, I was impressed by their insistence on the use of NP0/C0G ceramic bypass capacitors for the multiple power supply lines. And big NP0 is not cheap, requiring many layers and a tightly controlled process to produce defect-free parts. I recall reading about a part for the switching power supply of the international space station, which was about the size of a small loaf of bread and managed, iirc, 270 uF, I've forgotten at what voltage

Brad
  Reply With Quote
Old 15th July 2012, 08:23 PM   #24546
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: cambridge ma
Quote:
Originally Posted by 1audio View Post
Very quickly the ESR and its linearity dominates in this example. If your source is 160 Ohm and the esr is 50 milliOhms you have an attenuation of around 80 dB. MLCC's.

That would leave fundamental on the supply, no idea what portion of ESR is non-linear it can all be characterized.
__________________
Silence is so accurate.
  Reply With Quote
Old 15th July 2012, 08:36 PM   #24547
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: cambridge ma
Quote:
Originally Posted by bcarso View Post
For additional perversity note that some circuits, e.g., notoriously, low-dropout voltage regulators, have a propensity to oscillate when the output capacitor is too good, i.e., low ESR. So having a lossy part there can work better than a low-loss one. For perhaps better control of the situation one may wish to add some lumped series resistance with the lower-loss capacitors. But of course this does set a lower limit to the amount of attenuation of load current modulation.

Brad
I used to have a bag of "magic" 2.2uF caps from a surplus buy at Raytheon, they simply worked when nothing else did. An even tougher test is the 8 parallel video loads on the AD8010 datasheet, record setting (my) diff-gain and phase no special caps needed.
__________________
Silence is so accurate.
  Reply With Quote
Old 15th July 2012, 09:04 PM   #24548
diyAudio Member
 
serengetiplains's Avatar
 
Join Date: Feb 2004
Location: Canada
Quote:
Originally Posted by john curl View Post
That's how I feel about ceramic caps, as well, serengentiplains.
I really don't get a lot of this conversation, John. We handily accept that inductor performance differs (and audibly, for audio applications) with a change in the type of iron used. So, too, capacitors whose dielectric---the main determining factor of capacitor performance---has measurably different performance depending on its makeup.

Before I studied capacitors, I listened to them. I found in my listening that, as a general statement, and all other things being equal, teflons were better than polystyrenes, etc. Here's the hierarchy of the main capacitor types to which I listened (better first):

teflon
polystyrene
polypropylene
polycarbonate
polyester (mylar, PET)
electrolytic

Not that I needed such, but I had no measurement orientation to substantiate my personal listening observations, yet these were largely (almost overwhelmingly) corroborated by others who tend to slot capacitor sound in the hierarchy above.

Then Bateman decided to measure the things. His measurements confirmed the above hierarchy.

Notice that capacitor AC fidelity---the degree to which it approaches the theoretical ideal---generally follows its Dk (again, all other things being equal).
  Reply With Quote
Old 15th July 2012, 09:05 PM   #24549
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
Quote:
Originally Posted by scott wurcer View Post
That would leave fundamental on the supply, no idea what portion of ESR is non-linear it can all be characterized.
The more complete models of esr contain bulk R and the dielectric in series with each other and the K factor is temperature sensitive. The high K dielectrics add more to the esr than film or low K types. In the better film caps (lowest DA) the esr is limited by the bulk metal reistance which is very low.
For pwr supply bypass apps, the series Ls of the cap is very important for high freq component transients to be bypassed. The ceramic - by design - has inherantly low series L. But, as noted in many digital app notes those caps must be used as close as possible to the device (digial IC) or the series L of the pcb trace will be in series with the cap Ls and lower the effective freq range covered (the resonance of the C and Ls is the defining limit of the useful range the Cap can be effectively used as a capacitor). One reason why the MultiCap got a patent was, for its size, the Ls was much lower thus its self resonace was higher... making it more useful in filter apps over a wider freq range.. But still physical size maters in the series L and thus ceramic and small styrenes or silvered mica can do better in that app. Any claims as to hearing a change for the better in the sound is usually due to a lower Z PS over a wider bandwidth.. that might have been needed.

The reason for bypassing with smaller values is first and fundementally to extend the upper freq range which the capacitance is effective.... Once you go to a higher freq than the resonance of the Ls and C the usefulness as a cap deminishes and the circuit is that of an inductor.... not what you want from a cap. When That is the case, the sound often is cleaner and more details are easily heard. There seems to me to be new some spec limit that pwr supply (PS) Z needs to be -- something like at least 60DB below the circuit stage Z to be low enough... for high end or HD sound maybe -80 or more. Notice too that a tube circuit may not need as low a PS Z over wide freq range as SS amp would... Just speculation and a suggestion. --RNM

No magic but more info that makes using the best cap for the application easier to do and more affective.

Last edited by RNMarsh; 15th July 2012 at 09:27 PM. Reason: Low series L of ceramic caps is useful in high freq/speed apps -
  Reply With Quote
Old 15th July 2012, 09:13 PM   #24550
diyAudio Member
 
Chris Hornbeck's Avatar
 
Join Date: May 2011
Location: Little Rock
John Curl has previously mentioned that one of the magics of his later designs is that the final bypass capacitors are "mediated" by an active follower. This works good with vacuum valve stuff too.

All good fortune,
Chris
  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 01:32 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