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post #331 of 2933
Quote:
Originally Posted by Gary in MD View Post

Chris:

 

How high a frequency are we talking about here?  Above 20khz?  Way above 20khz?  Or down below 10khz were us old folks can still hear it?

 

Thanks, as always, for educating me.

 

Gary

 

Hi Gary,

 

Typically higher than 20 kHz.

The problem with a textbook linear power supply is that it is only trying to filter out the 60 Hz line frequency.

Unfortunately the diodes used in the rectifier have to turn on and off to convert AC into DC.

When this happens they ring a bit at a high resonant frequnency.

Guess where this switching noise goes?

In two directions, conducted out of your power amp (or pre-amp or whatever) down the power cord and into your other equipment AND into your power amp or pre-amp or whatever.

The filter capacitors in the power supply may not be able to filter out this very high frequency switching noise (often the power supply capacitors have too much inductance at high frequencies).  Power supply capacitors are a subject onto themselves. Some are better at rejecting power suuply noise than others. 

The switching noise is also radiated (i.e. broadcast) into nearby equipment.

Measuring this stuff is an art unto itself.

Not every audio company has the budget or equipment or expertise to do this.

The problem with this high frequency noise is that it may be demodulated down into the audio bandwidth.

 

Audiophile power cords may be designed to reduce all this noise from being absorbed and conducted.

The problem with the audiophile power cord companies is that they are not usually too forthcoming with design and measurement data.

One company that does advertise some measurement of noise rejection is Russ Andrews.

Cardas alludes to this when they mention that their shielded power cords may also include some extra capacitors.

You'll notice that a lot of these audiophile power cords are shielded. 

 

I used to work with some SwitchMode Power Supply designers. The boss "volunteered" me to help them get some EMI/RFI rejection/suppression certification for the North American and European markets. I learned enough to know how little I actually knew about the whole subject. Which is way more than Joe Average audiophile. But it was interesting to see how much crap noise the power supplies themselves generated.

 

I guess Odyssey doesn't trust some of these power cord and power bar vendors. I would also wager a guess that Odyssey does use some noise suppression techniques in their amps and may have some unfortunate experiences where a fancy audiophile power cord or power bar reacted badly with their amp and increased this noise.

 

Question for you:

do you notice that some amps have less fog, haze, noise, grain under or inside the music than other amps?

I also recall one reviewer referring to this as "spitch". 

post #332 of 2933
Quote:
Originally Posted by zilch0md View Post

Back in the early 90s, I was a an active amateur radio operator.  I used to work the HF SSB bands, speaking to other amateur operators around the world from my car, using a 100-Watt (RF output) Kenwood TS-50 transceiver that I powered with two parallel-wired 135 AmpHour deep-cycle marine batteries that were mounted in the trunk of my car and isolated from the alternator when I was using the radio.  

 

All the tables one can refer to for determining what gauge of wire should be used to support a given voltage/current over a known distance showed that I could use twinned 12-gauge power cables from the batteries to my radio.  And the radio seemed to work "fine" using twinned 12-gauge wires on each pole.  But... On the advice of a very seasoned amateur radio operator and author of a book on tuning for mobile operations, I replaced the twinned 12-gauge wires with 00-gauge cables!  

 

Double-ought cable is about the diameter of a dime and has a bend radius of about 18 inches!  It's rated to handle 200Amps at 600V!   My transceiver only pulled 25 Amps at 13.8V, but get this:  The power cable upgrade dropped my noise floor tremendously.  I had already been using every trick in the book to prevent noise from the car itself getting into my receiver's audio, but when I installed those 00-gauge power cables, all kinds of EMI and RFI coming from ambient sources outside the car suddenly vanished - I was then able to work very feint and distant stations, all over the globe, because I could finally HEAR them against a nearly pitch-black noise floor.  In radio, if you can't hear the other station, you won't even know they are there.   

 

Power cables act like antennas - sucking up all kinds of ambient noise - especially unshielded power cables.  Heavier gauges are much more immune to RFI and EMI than the smaller gauges - greatly reducing the need for an amp's power supply to filter anything out of the power.

 

Mike

 

The problem with anecdotal stories like this is that it is easy to draw an incorrect conclusion.

A heavier gauge cable is not more immune to RFI and EMI.

A heavier guage cable will have less DC resistance.

You must have done something else to reject noise coming down that DC line: something to increase the series inductance, increase the parallel capacitance, maybe you twisted the cables together.

Hard to say as I assume you had already tried using various line filters.  Did he give you any technical rationale for using 00 cable?

post #333 of 2933
Quote:
Originally Posted by preproman View Post

 

Another way:

 

After all amps have been burned in properly. You can spend a day each with each amp, writing down specific notes as you go.  At the end compare notes to each other.  This way you can listen to you favorite reference tracks back to back or how many times you want in a row, nailing down the specifics.  

 

Just a thought. 


An excellent suggestion... if only I were disciplined enough to do that.  The problem is that I will hear something in one amp, and then think "hmmm, I wonder what that sounds like on the [pick an amp]... and even if I fight the urge for a few minutes, it will start to distract me and I lose focus on the amp I'm listening to.  I will eventually, like within 10 minutes, give in and swap the amps out to "scratch that itch."  I have been able to go for an entire album, or maybe 10-15 songs on different albums, but have had a hard time going longer than that without switching.

 

But I might try to go at least a couple of hours doing it the disciplined way.  If I go totally crazy, though, I'm blaming you.  tongue_smile.gif 

post #334 of 2933
Quote:
Originally Posted by Chris J View Post

 

Question for you:

do you notice that some amps have less fog, haze, noise, grain under or inside the music than other amps?

I also recall one reviewer referring to this as "spitch". 

Chris:

 

I absolutely hear the difference in fog, haze, noise, grain in each of these amps.  I want to listen some more to make sure of what I've been hearing, but I can tell you that to me right now the Emotiva is very grainy/hazy, and the Millenia is very clear.  The two headphone amps are somewhere in between, with the MJ clearer than the Burson, at least so far.  But I'm only a few days into this, and most of these amps have only a few hours on them (the Burson is a demo unit, so I assume it has many hours on it... but I don't know how many).  Let's see how I feel in a week, after the amps are all burned in and I am all burned out.  biggrin.gif

post #335 of 2933
Quote:
Originally Posted by Chris J View Post

 

The problem with anecdotal stories like this is that it is easy to draw an incorrect conclusion.

A heavier gauge cable is not more immune to RFI and EMI.

A heavier guage cable will have less DC resistance.

You must have done something else to reject noise coming down that DC line: something to increase the series inductance, increase the parallel capacitance, maybe you twisted the cables together.

Hard to say as I assume you had already tried using various line filters.  Did he give you any technical rationale for using 00 cable?

 

Chris J,

 

This is the out-of-print book where it is discussed:  http://www.amazon.com/40-years-HF-mobileering-compendium/dp/0962426717

 

I don't own this book, but I know the use of 00-gauge power lines to reduce receiver noise is recommended within.  

 

How did going to so massive a gauge for the power cable reduce the receiver's noise floor?  I don't know.  

 

Did I make any other changes at the same time?  No, I didn't.  

 

As you might imagine, it was a lot of work running two lengths of 00 from the batteries at the rear of my car to the front - carving a giant "S"-shaped turn under the seats.  I had to use a torch to solder big lugs onto each end and then step down to smaller gauges right behind the transceiver to attach to a Molex connector.  When I had finished shoe-horning the cables into my car, believe me, I started operating my radio immediately and remember well how excited I was with the difference it made.  I was able to hear stations I would never have been able to hear before.  The feint background hash that I had routinely heard on just about every band was nearly gone.  Where previously, turning up the volume only turned up the hash, now, I could turn up the volume and work really weak stations.

 

I can understand that you could be uncomfortable with the lack of any scientific explanation in contrast to your understanding that gauge has no impact on EMI or RFI.  I can respect that, but I'm certain of my personal experience, and given that I'm no longer active as an amateur radio operator, I'm not interested in buying the book to find out if the author had extended an explanation.

 

I will say this, however - lots of amateur radio operators at the time expressed the same opinion you are expressing - that a 00-gauge power cord couldn't possibly make a difference in received noise.  

 

???

 

Thanks,

 

Mike

post #336 of 2933
Quote:
Originally Posted by AiDee View Post

Hi Gary, I do urge you to level-match if you haven't already planned this. It's amazing how much smaller differences become once this is done. The advantage is these smaller differences improve listening attention and skill.

Btw, an argument can be made level-matching isn't perfect. I suspect different amps have different sweet-spots, FWIW. If true this would support the unmatched approach.

In my experience with DACs (very subtle differences in general) the time gap while switching isn't a problem. I took care to not think and not mentally replay what I just heard. Blank mind seemed best.

Some - who don't seem to know much about memory - will tell you aural memory is unreliable and faulty. True, as far as it goes. However, human memory depends on a process called "chunking". What's really at issue is not the reliability of aural memory (bad) but the consistency with which we identify attributes such as "dry", "warm" and so on. The latter I think we must assume is good, with experience. If it isn't, the entire premise behind bothering to share and discuss our audiophile experience is undermined!

Cheers, Andre

 

Andre:

 

I'm gonna go get a cheap SPL meter and do at least crude level matching.  I have noticed a considerable difference in the sound quality from the MJ in particular between "slightly too loud" and "just right" so I think I owe it to all of the amps to match levels at least somewhat.

post #337 of 2933
Hi Gary, I hesitate to recommend my one and only head-fi review to date (indeed to recommend any posts of mine period) as it hardly makes me expert, but if you can find it you may find my Schiit bifrost versus EE MiniMax versus Meier Stagedac has some interesting comment on the problems of review listening. I only mention this because I'm an active researcher and statistician, and measurement of 'ambiguous stimuli' frequently comes into my work. In the review I commented on some aspects of cognition that might be helpful.

It is long though and failing that, the cognitive literature suggests that what you noted below may interfere with memory, specifically with 'chunking' (conversion of sense data to a language-based label such as 'dry', 'sweet') and encoding into long-term memory = the memory pegs (descriptive words) you recall and subsequent interpretations you write so well.

My practice was to stop listening eek.gif if I noticed my mind was either (a) too active or (b) too tired. This slowed things down but - for me at least - it was very rewarding.

Btw, as there is a risk you are feeling flooded by now with 'well-meant' advice like mine wink.gif, feel free to ignore.

It's more important you continue to review than than you satisfy every last obsessive, such as me biggrin.gif

Cheers, Andre
Quote:
Originally Posted by Gary in MD View Post


An excellent suggestion... if only I were disciplined enough to do that.  The problem is that I will hear something in one amp, and then think "hmmm, I wonder what that sounds like on the [pick an amp]... and even if I fight the urge for a few minutes, it will start to distract me and I lose focus on the amp I'm listening to.  I will eventually, like within 10 minutes, give in and swap the amps out to "scratch that itch."  I have been able to go for an entire album, or maybe 10-15 songs on different albums, but have had a hard time going longer than that without switching.

But I might try to go at least a couple of hours doing it the disciplined way.  If I go totally crazy, though, I'm blaming you.  tongue_smile.gif  
post #338 of 2933
Quote:
Originally Posted by zilch0md View Post

Chris J,

This is the out-of-print book where it is discussed:  http://www.amazon.com/40-years-HF-mobileering-compendium/dp/0962426717

I don't own this book, but I know the use of 00-gauge power lines to reduce receiver noise is recommended within.  

How did going to so massive a gauge for the power cable reduce the receiver's noise floor?  I don't know.  

Did I make any other changes at the same time?  No, I didn't.  

As you might imagine, it was a lot of work running two lengths of 00 from the batteries at the rear of my car to the front - carving a giant "S"-shaped turn under the seats.  I had to use a torch to solder big lugs onto each end and then step down to smaller gauges right behind the transceiver to attach to a Molex connector.  When I had finished shoe-horning the cables into my car, believe me, I started operating my radio immediately and remember well how excited I was with the difference it made.  I was able to hear stations I would never have been able to hear before.  The feint background hash that I had routinely heard on just about every band was nearly gone.  Where previously, turning up the volume only turned up the hash, now, I could turn up the volume and work really weak stations.

I can understand that you could be uncomfortable with the lack of any scientific explanation in contrast to your understanding that gauge has no impact on EMI or RFI.  I can respect that, but I'm certain of my personal experience, and given that I'm no longer active as an amateur radio operator, I'm not interested in buying the book to find out if the author had extended an explanation.

I will say this, however - lots of amateur radio operators at the time expressed the same opinion you are expressing - that a 00-gauge power cord couldn't possibly make a difference in received noise.  

???

Thanks,

Mike

Mike,
I gotta admit that this does leave me scratching my head!
You clearly heard what you heard! It's hard to fake better reception.
Inductance that is linear WRT frequency? Who knows!
I'll stop bitching about this 'cos I do hear differences between some audiophile power cords, and the technical reasons why do confound me! Shielded cable and......what else? Magic weaving and cable twisting?
Chris
post #339 of 2933
Quote:
Originally Posted by AiDee View Post

Hi Gary, I hesitate to recommend my one and only head-fi review to date (indeed to recommend any posts of mine period) as it hardly makes me expert, but if you can find it you may find my Schiit bifrost versus EE MiniMax versus Meier Stagedac has some interesting comment on the problems of review listening. I only mention this because I'm an active researcher and statistician, and measurement of 'ambiguous stimuli' frequently comes into my work. In the review I commented on some aspects of cognition that might be helpful.

It is long though and failing that, the cognitive literature suggests that what you noted below may interfere with memory, specifically with 'chunking' (conversion of sense data to a language-based label such as 'dry', 'sweet') and encoding into long-term memory = the memory pegs (descriptive words) you recall and subsequent interpretations you write so well.

My practice was to stop listening eek.gif if I noticed my mind was either (a) too active or (b) too tired. This slowed things down but - for me at least - it was very rewarding.

Btw, as there is a risk you are feeling flooded by now with 'well-meant' advice like mine wink.gif, feel free to ignore.

It's more important you continue to review than than you satisfy every last obsessive, such as me biggrin.gif

Cheers, Andre

I think I know what you mean Andre, I had a really hard time getting my head around an IBasso D12 vs. Matrix M Stage comparison I posted somewheres here on Head Fi.
Edited by Chris J - 7/1/13 at 4:20pm
post #340 of 2933

Andre:

 

I appreciate your insights on this, and I do stop critical listening if I find that I can't focus.  That's when I start writing! 

 

But semi seriously, I may or may not be typical (probably not, I'm not typical in any other way, why should this be any different), but I find that I am a very focused, analytical (as in exceedingly anal) thinker/listener, and when I start listening to a song I am able to hone in on particular things of interest and tune out all of the other things.  I will listen for the sound of a cymbal strike at a particular part of a song.  And I will listen again.  And again.  In my mind, having listened to live music and well-reproduced recorded music for too many decades, I know how I want that cymbal strike to sound.  And to not sound.  Same for human voices.  I have heard enough of them (in fact, too much of some of them) to know how I want them to sound.  And to not sound.  Same for every part of the recording.  I will literally go through and pick apart as many sounds as I can from every part of the spectrum.  And I will compare each of those sounds to my reference sound using my mark-1 internal brain sound comparatator (or is that comparometer?).  Those sounds that most closely match my internal brain reference are "good" those that match poorly are "bad". 

 

It is totally subjective.  But it is pretty precise, in that I can tell you exactly why I did or did not like the performance of a particular hardware setup.  By varying only one element in the chain, I can isolate the differences to the changed elements.  That's why I have so much trouble fighting the urge to switch amps (or headphones last year).  I hear the particular sound of a particular instrument that a particular amp reproduces within a small part of a song, and I know whether I think it is "good" or "bad" relative to my internal meter, but I'm not quite sure how it compares to the other amps, since I don't necessarily trust my memory to give me that relative data accurately.  So I will swap out the component and listen for the same sound.  If I can do that relatively quickly, or the difference is particularly stark, then I definitely trust my memory enough to rank the competitors.  But the longer I go between hearing the different components playing exactly the same piece of music, the less confidence I have in my analysis, particularly for fairly subtle differences.  That's why I value quick swaps.  Of course if one piece of equipment really performs differently than the others across a wide spectrum of sounds, you can categorize it pretty quickly as either good or bad, and I have found that in those cases it doesn't take me long to come to conclusions -- mere minutes, in some cases. 

 

Note that I ended up with the LCD-3s because across the spectrum they most closely reproduced what my brain said each of the sounds was supposed to be.  It didn't take me very long to determine that it was definitely better (against my personal reference) than everything else I was comparing it against.  The LCD-2 was closest to my reference, but was lacking in that last dimension of realism in the sound.  The cymbals weren't quite as life-like (or more precisely "Gary's-reference-like"), the voices didn't quite have that "in the same room singing to me right now" quality.  But what took me 2 weeks of intense "comparatating" to figure out was whether the -3s were enough better than the -2s to merit paying an extra $1000.  In the end, after too many hours of back and forth, I decided they were, because I feared that if I went with the -2s, I would forever be asking myself "I wonder what that would have sounded like on the LCD-3s."  Now I don't have to worry about that, at least.

 

Of course, you can go absolutely batty doing comparisons this way if the hardware all performs similarly.  At that point I need to back off and just listen to the music.  It really will soothe your soul...  if you can just sit back and let it. 

 

Make sense?  Ready to call the guys in the white coats to drag me off to the asylum?  Well, at least wait until I finish this comparison.

post #341 of 2933
I seem to remember reading that, and thinking it was a darn good review Chris!

Gary, I work with some people who can help with the white coats thing wink.gifbiggrin.gif

For reasons and based on literatures too many to reasonably go into here, and because of what I've observed when people share experience on these forums, I don't think this thing we do as audiophiles is totally subjective at all. This may just be my scientific bias though!

Quote:
Originally Posted by Chris J View Post

I think I know what you mean Andre, I had a really hard time getting my head around an IBasso D12 vs. Matrix M Stage comparison I posted somewheres here on Head Fi.
post #342 of 2933
Gary,
I think you are ready for the Baltimore asylum where they had Hannibal Lector locked up!
I don't think you need the Hannibal mask, though.
tongue.gif
Chris
post #343 of 2933

One more quick note before I go do other stuff I should have done hours ago before you folks diverted me:  I talked to Klaus from Odyssey today, and the elves are almost done with my amp, but they didn't have the face plate done, since they don't usually stock many of those (most people just get the Khartago power amp... I'm getting the Cyclops, which obviously has a hole in the face plate for the volume control).  The face plates are fabricated outside of the Odyssey shop, and the supplier had not delivered mine yet.  Once they do, probably by the end of the week, the part needs to be etched and anodized (or vice-versa?), and then it will be attached, and voila, the job will be complete, since the amp itself is built.  I expect shipping ~next Monday, and the amp to be here by the end of next week (7/12).  I would probably have had to send back the Burson by then, and also the Mjolnir if I decide not to keep it, but I still want to bring in the Odyssey, so I'll beg the Cable Co for a few more days on the loan, and if I have to sell the MJ myself after the comparison is over because I missed Schiit's return window, well, so be it.  If I can keep my loss to ~$50-100 or so, that wouldn't be too bad. 

 

Now, back to all of the other stuff I need to do so that I can get back to comparing amps later tonight.

post #344 of 2933
Quote:
Originally Posted by Gary in MD View Post

Folks:

 

...snip....  As in I've had to repair and re-rip a couple of CDs that I had copied using Exact Audio Copy, because even with EAC's error correction I could hear noise in the files from bad digits.  ... snip ...

I've experienced similar performance with EAC.  Have you tried dBPowerAmp?  I've not had the same issues ( non-bit perfect rips ) with it that I have had with EAC.  dBPowerAmp is more obvious in reporting bad or suspect rips.  

 

 

IME, YMMV.. blah blah disclaimer blah blah  :)

post #345 of 2933

Folks:

 

Just a quick note to let you know I didn't fall off the end of the Earth, though it seems like it at times.  I have been hard at work comparing the Emo to the MJ.  I'll have a full write-up tomorrow, but suffice it to say at least one of them is going back pretty soon. 

 

I have also been trying to find/diagnose a noise problem in the Millenia.  Turns out a large part of the noise I heard in the recordings was not in the recordings.  I spent probably a total of 8-10 hours trying various tunes, some of which were noisy, some weren't, which made the whole problem hard to figure out.  I thought it was the resistor box for a while, because one of the banana jacks isn't very tight.  That might be a problem, but it isn't causing most of the noise.  I was getting pretty frustrated when I just decided to try something totally off the wall.  I disconnected the power supply and put 8 AA alkaline batteries in the back of the Millenia.  Voila, no more noise, at least not audible noise.  The characteristics of the amp also changed a little, but more on that in a future episode.  Now I need to go to sleep, because I haven't slept much the past couple nights as this problem was driving me crazy(er).

 

I will never doubt you power cord believers again. 

 

Gary


Edited by Gary in MD - 7/4/13 at 12:21am
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