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Ken Ishiwata on CMOS and the modern PCB - Page 2

post #16 of 29
Thread Starter 
Quote:
Originally Posted by BlindInOneEar View Post

Actually, I think I spent more than ten minutes on that video, having to replay a few bits to grapple with Ken's accent.  Even so I'd still not feel comfortable attempting to paraphrase much of what he said.  However I would like to point out a few things. 

 

First, there are acknowledged tests, accepted industry wide, for measuring the performance of an audio component.  If Ken is going to dismiss these tests out of hand as being meaningless or incomplete then it is incumbent upon him to explain and show why they are deficient and to fully describe his proposed alternative.  In that video he did neither.  Sorry, sighted listening tests are not an acceptable substitute for valid science.

 

Secondly, at one point he seems to be saying that mid and high frequencies (in audio terms) pass through a circuit more quickly than lower frequencies.  I am completely at a loss as to how this can happen.  I submit that an audio circuit neither knows nor cares whether it is passing a 100 hz signal or a 1,000 hz signal.  If a midrange signal does pass through a circuit faster than a bass signal, how is it no one noticed it before Ken?  Why hasn't Ken published a paper describing this effect?  Why hasn't anyone else?  This would seem to be a significant issue that circuit designers would have to address, yet I'm unaware of any reputable discussion of the matter.

 

Ken struck me as being an amiable guy and an inveterate schmoozer.  Good for him that he's got such a good job.  However, I'd be very surprised if he actually spent much time at the test bench while any of his "creations" were being designed. 
 

 

Its a common misconception that he micro-manages the 'KI' gear - he made it clear to an Aussie journalist that he makes recommendations to each of the design teams at Marantz and lets them do their jobs. I assume he then spends time with the end result before letting Marantz ship the new 'KI', but that's all academic now that he has hung up his golden ears. Would you be happier if they released a 'Dr Dre' model ?   rolleyes.gif

 

(and I agree that some of his explanation of how he 'balances' the sound across different frequencies sounded kinda loopy, but it wasnt helped by the drone from WHF agreeing with everything he said without pushing him for clarification. Clearly, English isnt his first language, but Marantz isnt asking us to buy recorded KI interviews)

post #17 of 29
Quote:
Originally Posted by Mauricio View Post

 

This is a well-known phenomenon.  It is often called group delay and a related phenomenon is the the concept of phase difference.


Sweet!  I learn something everyday!  What do people call it on the not so often times when they don't call it group delay? Just kidding!  wink.gif

 

But seriously, is group delay really an issue with competently designed amplifiers?  Or other electronic components?  Or is it an issue that has been pretty thoroughly engineered out of electronics by this point?  I ask because while I often read about group delay in conjunction with loudspeakers, I don't seem to recall ever hearing it brought up in things like amplifiers or DACs.  Is my original point that competent amplifiers don't care whether they are playing a 100hz signal or a 1,000 hz signal and that they will treat both the same correct or am I missing something here?  

 

Thanks for any input you might have! 

post #18 of 29
Quote:
Originally Posted by estreeter View Post

 

Its a common misconception that he micro-manages the 'KI' gear - he made it clear to an Aussie journalist that he makes recommendations to each of the design teams at Marantz and lets them do their jobs. I assume he then spends time with the end result before letting Marantz ship the new 'KI', but that's all academic now that he has hung up his golden ears. Would you be happier if they released a 'Dr Dre' model ?   rolleyes.gif

 

(and I agree that some of his explanation of how he 'balances' the sound across different frequencies sounded kinda loopy, but it wasnt helped by the drone from WHF agreeing with everything he said without pushing him for clarification. Clearly, English isnt his first language, but Marantz isnt asking us to buy recorded KI interviews)


Would I be happier if Marantz released a Dr. Dre model?  Ouch!  That shot hurt!  biggrin.gif

 

I've actually thought Marantz has put together some pretty good stuff for a pretty long time.  I think their gear speaks for itself.  I tuned in to that video hoping to see a discussion of engineering issues but instead got ten minutes of vague, audiophile-speak.  I was disappointed.  However, it's not fair of me to blame the messenger.  Marantz makes good stuff, but so do a lot of other companies.  The engineers know how to design the circuits, but the marketers know that people want reassurance that the stuff actually works.  Ken's job is to provide that reassurance and he apparently does a good job of it.  Certainly Marantz thought they were getting value for their money by keeping him on the payroll.  I guess I'm just jealous that I don't have a cool job like that!

post #19 of 29
Quote:
Originally Posted by OJNeg View Post

Really? My Marantz receiver doesn't even have a dedicated headphone stage. It simply uses resistor drops from normal speaker outputs to the headphone jack.

I agree.
Basically, this is the very definition of an after thought.
Take a 50 Watt power amp and add a pair of 330 ohm resistors and a headphone jack.
Hmmmmm, sounds like an after thought to me.
Most of those vintage receviers have ( by today's standards) an obscenely high output impedance.
post #20 of 29
Quote:
Originally Posted by OJNeg View Post



The Marantz receiver that I'm talking about is a vintage Marantz 2220, manufactured in 1973 IIRC. Not a high end unit by any means (none of the 2xxx series were to be fair), but it sounds great with my loudspeakers. The headphone jack was obviously an afterthought though, but it functions well enough.

I'm just trying to understand the notion that these vintage units had a good headphone output. As far as I know, using resistor drops was common technique, but maybe some other vintage units actually did have quality headphone outputs.

Yep, I can't think of one single vintage receiver schematic I've looked at that didn't use a pair of resistors on the output of the power amp. And I've looked at quite a few.
post #21 of 29
Quote:
Originally Posted by BlindInOneEar View Post

Marantz makes good stuff, but so do a lot of other companies.  The engineers know how to design the circuits, but the marketers know that people want reassurance that the stuff actually works.  Ken's job is to provide that reassurance and he apparently does a good job of it.  Certainly Marantz thought they were getting value for their money by keeping him on the payroll. 

 

I understand the reason why marketing departments exist, but as someone who understand electronics and audio a bit more than the average consumer, I feel like I'm being taken for an idiot sometimes. The truth is, there's no big innovation that these amplifier designers are going to come up with in this day and age. It's well documented that solid-state Class A amplifiers with similar specs will all sound and perform the same. So what do these manufacturers have to do to sell their product when every other hi-fi manufacturer is selling the same product? Marketing.

 

My point is, besides basic features, power output, and aesthetics, there's not much to differentiate these products. Instead these brands will try to sell a more ethereal, intangible idea to separate their amp from the crowd. That being said, I'm big Marantz fan and I'd like to own a pair of their mono blocks someday (when I win the lottery).

 

 

Quote:
Originally Posted by Chris J View Post


I agree.
Basically, this is the very definition of an after thought.
Take a 50 Watt power amp and add a pair of 330 ohm resistors and a headphone jack.
Hmmmmm, sounds like an after thought to me.
Most of those vintage receviers have ( by today's standards) an obscenely high output impedance.

 

I never use my headphones with my 2220, but I've tried it before and I noticed the sound was lacking. Bass was loose, which I imagine comes from the high output impedance (and therefore low dampening factor).

 

Correct me if I'm wrong, but weren't older headphones usually higher impedance? They probably could have gotten away with high output impedance back then.

post #22 of 29
Quote:
Originally Posted by BlindInOneEar View Post


Sweet!  I learn something everyday!  What do people call it on the not so often times when they don't call it group delay? Just kidding!  wink.gif

 

But seriously, is group delay really an issue with competently designed amplifiers?  Or other electronic components?  Or is it an issue that has been pretty thoroughly engineered out of electronics by this point?  I ask because while I often read about group delay in conjunction with loudspeakers, I don't seem to recall ever hearing it brought up in things like amplifiers or DACs.  Is my original point that competent amplifiers don't care whether they are playing a 100hz signal or a 1,000 hz signal and that they will treat both the same correct or am I missing something here?  

 

Thanks for any input you might have! 

 

Not so relevant for well designed and engineered modern amps, no.  Still very relevant for loudspeaker design and loudspeaker fidelity.  While we are on the subject, one of the drawbacks of passive crossovers is the group delay and phase differences that they introduce to the signal.

post #23 of 29
Quote:
Originally Posted by OJNeg View Post

I understand the reason why marketing departments exist, but as someone who understand electronics and audio a bit more than the average consumer, I feel like I'm being taken for an idiot sometimes. The truth is, there's no big innovation that these amplifier designers are going to come up with in this day and age. It's well documented that solid-state Class A amplifiers with similar specs will all sound and perform the same. So what do these manufacturers have to do to sell their product when every other hi-fi manufacturer is selling the same product? Marketing.

My point is, besides basic features, power output, and aesthetics, there's not much to differentiate these products. Instead these brands will try to sell a more ethereal, intangible idea to separate their amp from the crowd. That being said, I'm big Marantz fan and I'd like to own a pair of their mono blocks someday (when I win the lottery).



I never use my headphones with my 2220, but I've tried it before and I noticed the sound was lacking. Bass was loose, which I imagine comes from the high output impedance (and therefore low dampening factor).

Correct me if I'm wrong, but weren't older headphones usually higher impedance? They probably could have gotten away with high output impedance back then.

A lot of them were hign impedance: 600 ohm, even 2,000 ohm.
But it seems that a few of them were also 8 ohm, 60 ohm, etc.
Mathematically, if you output up to 20, 30 or even 40 Vrms then add an output resistor of 220 or 330 ohms you can get reasonabe control over the volume with just about any impedance headphone. I guess they didn't care too much about headphones back then.
post #24 of 29
Quote:
Originally Posted by estreeter View Post

Mauricio, I think I know where you are going with this, and I'm not going there.

For the rest, here is the Youtube interview - have at it. 



BTW, the link ws gone before I had a chance to waste my time looking at it, was the hell was KI on about? The output current limits of DACs? Which don't drive headphones directly anyway?
Does he explain why the THD of a modern DAC is so low irregardless of his histrionics and rhetoric?
post #25 of 29

The link you re-posted still works for me.  Click on the link, then click on the "Watch on Youtube" link that appears in the middle of the screen and it should open up the video in a new tab.  Or heck, maybe this link will work. http://www.youtube.com/watch?v=A2QPePifDQI&feature=player_embedded    Have fun! 

 

Ken's English is heavily accented.  Even setting that aside, at times it's hard to understand what he is talking about.  I'll be interested to read your thoughts on his little talk.
 


Edited by BlindInOneEar - 6/13/12 at 12:56pm
post #26 of 29
Thread Starter 

If any of you read the Vintage Receivers thread, Skylab mentioned that he considers many vintage headphones to sound dismal compared to their modern counterparts. 

 

I also think some of us are ignoring the sensitivity issue when discussing '6-ohm' vintage headphones, but I'm told we got the slew of high impedance phones courtesy of Beyerdynamic's attempt to impose a 'standard', following years of studio equipment being based around high impedance headphones which could be safely plugged into almost anything. Is output impedance an issue with the 50-ohm HE-6 ? Beats me, but I'm guessing it would be a much bigger issue with my 150-ohm RE-262s ......... 

 

After watching a 30W Lepai T-amp driving a stack of 4-ohm DJ speakers, I'm inclined to believe anything is possible. Whether its enjoyable or not is a totally different question !  wink.gif

post #27 of 29
Quote:
Originally Posted by estreeter View Post

If any of you read the Vintage Receivers thread, Skylab mentioned that he considers many vintage headphones to sound dismal compared to their modern counterparts. 

I also think some of us are ignoring the sensitivity issue when discussing '6-ohm' vintage headphones, but I'm told we got the slew of high impedance phones courtesy of Beyerdynamic's attempt to impose a 'standard', following years of studio equipment being based around high impedance headphones which could be safely plugged into almost anything. Is output impedance an issue with the 50-ohm HE-6 ? Beats me, but I'm guessing it would be a much bigger issue with my 150-ohm RE-262s ......... 

After watching a 30W Lepai T-amp driving a stack of 4-ohm DJ speakers, I'm inclined to believe anything is possible. Whether its enjoyable or not is a totally different question !  wink.gif

No I'm not ignoring sensitivity.
Yes, output impedance is an issue;
high output impedance always leads to poorer electrical efficiency, often leads to FR aberations, and often creates additional distortion due to poor damping factor.

Edit:
I just realized the link doesn't come up on my iPad, I'll have to use my computer.
Edited by Chris J - 6/14/12 at 4:17am
post #28 of 29
Thread Starter 
Quote:
Originally Posted by Chris J View Post


No I'm not ignoring sensitivity.
Yes, output impedance is an issue;
high output impedance always leads to poorer electrical efficiency, often leads to FR aberations, and often creates additional distortion due to poor damping factor.
Edit:
I just realized the link doesn't come up on my iPad, I'll have to use my computer.

 

I'm not saying high output impedance is a good thing - simply pointing out that there is an historical reason for that approach. The 'FR aberrations and additional distortion' arent universal across low impedance cans - even V admits that in the course of his rants against various gear guilty of said crime. The main issue seems to be with sensitive IEMs. and those just didnt exist in 1985. 

post #29 of 29
Quote:
Originally Posted by estreeter View Post

 

I'm not saying high output impedance is a good thing - simply pointing out that there is an historical reason for that approach. The 'FR aberrations and additional distortion' arent universal across low impedance cans - even V admits that in the course of his rants against various gear guilty of said crime. The main issue seems to be with sensitive IEMs. and those just didnt exist in 1985. 

 

I think we can all agree that I spelt "aberrations" wrong.redface.gif

 

The problem with IEMs is that a lot of headphone amps have too much gain for IEMs.  A headphone amp with a low output impedance, very low noise and a Voltage gain of 0 dB would be what most IEMs need.

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