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post #316 of 2631

Can somebody explain the physics behind why the power cord makes a difference?  I don't doubt that people are hearing differences (hey, I now believe in magic boxes!), but I'd be more willing to part with $ if somebody could explain the mechanism that makes it work.

post #317 of 2631
Quote:
Originally Posted by Gary in MD View Post

Can somebody explain the physics behind why the power cord makes a difference?  I don't doubt that people are hearing differences (hey, I now believe in magic boxes!), but I'd be more willing to part with $ if somebody could explain the mechanism that makes it work.
Passive filtering. Power lines pick up all kinds of EM from the environment, particularly high frequency energy. Taking out as much as you can frees up the power supply to work with cleaner power.
post #318 of 2631

Its a crap shoot. Some hear a positive result. Others negative. Most don't. I might get a Pangea AC-9 for my amp just for a sturdier power cord.

post #319 of 2631

Folks:

 

Mjolnir is now in da loop.  It is about the same size as the Emo Mini-x, comes in a spartan box with a bit of foam protection and the funniest instruction booklet I've ever read, not that I normally read instructions or anything.  But when you read on the cover about the name (it's Thor's hammer) and they tell you "just don't try to use it to pound in any nails.  That would void the warranty." it kind of piques your interest.  There are a few other gems in there, but that doesn't matter, this is a comparison of performance, not manufacturer humor.  So I'll get on with it.

 

Again, remember that these are my first impressions, right out of the box.  I reserve the right to change my  mind after I've got some time on these amps, and gotten myself all confused and befuddled. 

 

The MJ is a very nice amp.  I now understand when folks say it is "in your face".  The sound is clean, but It has an edginess to it, more than the Burson has.  Harsh is too harsh a word, just like with the Burson, but if you like your sounds mellow and warm, this amp is not for you. 

 

The sound stage seems bigger to me than the Burson's.  Most of the little things I listen for in every song I use as a demo are there, so detail is good.  Not as good as the TBI, but I've never heard anything like that little bugger -- it clearly reveals stuff that I'm guessing no producer ever thought anybody would hear, which is both good and bad.  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.  Once I knew to listen for it, I could sort of hear it on the other amps, but only if I listened real closely. Now that's detail...

 

But back to the MJ.  Bass is really tight: kick drums pop and stop, no boominess at all.  Pianos and vibraphones sound right, but maybe a little cold.  There is no mistaking this for anything but a solid state amp -- it has a clear SS signature. So do the Burson and Emo, but the TBI sounds like a tube amp, when in fact it is a class BD SS.

 

Just listened to some Dave Matthews, (Riff, from "Away from the World), and could hear the chair creaking in the beginning -- first noticed with the TBI, of course, but definitely there with the MJ.  Also there is a bit of harshness near the end of the song as it reaches crescendo, also there a bit with the Millenia, but controlled, whereas with the MJ it gets a bit out of hand.  Not really a very pleasant sound, and it would be very fatiguing if I listened to it for long.  Here's hoping that will smooth out as I get some more hours on the amp. 

 

Okay, enough for now... I have to go get some food in me... need to keep up my strength for some more listening later.

post #320 of 2631
Quote:
Originally Posted by preproman View Post

What tube amp do you have in mind?

I am looking at possibly a PrimaLuna amp or one of those Chinese made ones. Transformer coupled of course. Thanks
post #321 of 2631
Quote:
Originally Posted by Happy Camper View Post


Passive filtering. Power lines pick up all kinds of EM from the environment, particularly high frequency energy. Taking out as much as you can frees up the power supply to work with cleaner power.


Okay, but doesn't the amp take out all of that noise?  Most of them are converting 120V AC power to something else, using transformers, capacitors, etc., etc., etc.  How much of that noise gets through?

 

Note that Odyssey wants their amp plugged right into the wall, no power strips or conditioners, and had me measuring voltages to enable them to bias the amp.  Not sure how much good that's gonna do, since the voltage levels range anywhere from 116 in the middle of the day to 120 at night, so its kind of a moving target.  But is his approach also related to filtering the AC power?

post #322 of 2631
Nice impressions Gary. Purrin famously coined the phrase "obsessively vigilant" for the Mojo (Chris J's name for it) IIRC.

Jason liked it so much you can even buy the tee shirt!
Quote:
Originally Posted by Gary in MD View Post

Folks:

Mjolnir is now in da loop.  It is about the same size as the Emo Mini-x, comes in a spartan box with a bit of foam protection and the funniest instruction booklet I've ever read, not that I normally read instructions or anything.  But when you read on the cover about the name (it's Thor's hammer) and they tell you "just don't try to use it to pound in any nails.  That would void the warranty." it kind of piques your interest.  There are a few other gems in there, but that doesn't matter, this is a comparison of performance, not manufacturer humor.  So I'll get on with it.

Again, remember that these are my first impressions, right out of the box.  I reserve the right to change my  mind after I've got some time on these amps, and gotten myself all confused and befuddled. 

The MJ is a very nice amp.  I now understand when folks say it is "in your face".  The sound is clean, but It has an edginess to it, more than the Burson has.  Harsh is too harsh a word, just like with the Burson, but if you like your sounds mellow and warm, this amp is not for you. 

The sound stage seems bigger to me than the Burson's.  Most of the little things I listen for in every song I use as a demo are there, so detail is good.  Not as good as the TBI, but I've never heard anything like that little bugger -- it clearly reveals stuff that I'm guessing no producer ever thought anybody would hear, which is both good and bad.  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.  Once I knew to listen for it, I could sort of hear it on the other amps, but only if I listened real closely. Now that's detail...

But back to the MJ.  Bass is really tight: kick drums pop and stop, no boominess at all.  Pianos and vibraphones sound right, but maybe a little cold.  There is no mistaking this for anything but a solid state amp -- it has a clear SS signature. So do the Burson and Emo, but the TBI sounds like a tube amp, when in fact it is a class BD SS.

Just listened to some Dave Matthews, (Riff, from "Away from the World), and could hear the chair creaking in the beginning -- first noticed with the TBI, of course, but definitely there with the MJ.  Also there is a bit of harshness near the end of the song as it reaches crescendo, also there a bit with the Millenia, but controlled, whereas with the MJ it gets a bit out of hand.  Not really a very pleasant sound, and it would be very fatiguing if I listened to it for long.  Here's hoping that will smooth out as I get some more hours on the amp. 

Okay, enough for now... I have to go get some food in me... need to keep up my strength for some more listening later.
post #323 of 2631
I'm completely on the fence about power cords but at least two EEs I respect take it seriously.

Steve Deckert of Decware has a white paper to which unfortunately I've lost the link. It was a typically creative-speculative effort of Steve's, but I was struck by his observation that the cable in your wall is nicely protected and routed and separated from most environmental EM, but the few feet between the wall and your gear is a different story.

A piece of the puzzle maybe confused.gif
post #324 of 2631
Quote:
Originally Posted by Gary in MD View Post


Okay, but doesn't the amp take out all of that noise?  Most of them are converting 120V AC power to something else, using transformers, capacitors, etc., etc., etc.  How much of that noise gets through?

Note that Odyssey wants their amp plugged right into the wall, no power strips or conditioners, and had me measuring voltages to enable them to bias the amp.  Not sure how much good that's gonna do, since the voltage levels range anywhere from 116 in the middle of the day to 120 at night, so its kind of a moving target.  But is his approach also related to filtering the AC power?

Does the amplifiers's power supply take out all that noise?

Strictly speaking, it is impossible to take out all that noise.
In practice, it is quite possible to take out quite a bit.
How much is taken out?
IT DEPENDS.
I'm sure that there are quite a few amplifier designers don't even bother trying to reject high frequency noise. I would guess that most of them are only trying to filter out the 60 (or 50) Hz line frequency.
I understand that Moon (Sim Audio) spends a fair amount of money on trying to filter out EMI/RFI (i.e. extremely high frequency noise).
Keep in mind that every power supply, when it converts AC into DC, this process always creates a fair amount of high frequency noise.
Where does all this high frequncy noise go?
Some is conducted down the power line to your other components, and some of it is radiated (i.e. broadcast) to your other components.

Too bad a lot of cable vendors don't like giving out much real, concrete info. So who knows what a lot of these cable companies are really trying to do or how they do it.
Edited by Chris J - 6/30/13 at 6:12pm
post #325 of 2631

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.

 

And as to my other line of posting, the MJ either got a lot smoother after several hours, or I just became accustomed to the sound, because it sounded much better this evening than it did earlier.   I also turned the volume down a bit, which helped make it less fatiguing (imagine that).  Overall, a very pleasant evening of listening. 

 

Now that I have a "baseline" or basic understanding of each amp my plan is to do a bit more aggressive comparing of them, going back and forth between amps listening carefully to the same songs, or parts of songs, over and over until I can clearly hear any/all differences in the amps.  It isn't true A/Bing since I'm not volume matching and switching takes a minute or more between amps (depending on how many wires have to be changed) meaning I'm depending on remembering what I heard a minute or more ago, instead of what I heard a split second ago.  However, after switching many many many many many times and listening to the same few songs over and over and over and over I get a pretty good sense of the differences between the amps. 

 

I'll also be bringing my Adcom pre-amp back into the mix -- as a competitor, not in the chain for the other amps. 

 

I have to work tomorrow, so I probably will spend only a few hours starting the comparisons.  I expect to spend a lot more time on Tuesday through Thursday on this.  Depending on how things turn out -- i.e., how quickly I come to a conclusion about various amps -- I will then change things up and use the Burson's DAC, to see if it changes my opinions of any of the players.  After that I might start using my Adcom as a pre-amp for all of the others, to see how that changes things.  By then, which is probably at the end of this week or next weekend, I hope the Odyssey is here, but at this point I have no idea when it will show up.  I need to start sending stuff back in about a week, so here's hoping it shows up before I start that process. 

 

Anybody who has suggestions on other ways of doing the comparison, or other things they'd like to work into the process, just let me know.  I'm open to any ideas you might have.

 

Gary

post #326 of 2631
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
post #327 of 2631

Gary,

 

Send me a PM with your mailing address, and I will Priority Mail these items to you for the duration of this truly precious experiment you are performing:

 

 

 

http://www.head-fi.org/t/659603/introduction-about-hs2-headphone-signal-switcher

 

This includes four interconnect cables and I'll add a couple of 3.5-to-6.3mm adapters, so that you can feed the switching unit from at least two amps' 6.3mm headphone jacks simultaneously.  Plug your headphones into the front of the switch box and you'll be able to go back and forth between the two amps, quite rapidly.  If you have some more adpaters, you can go back and forth between as many as four amps, but they all have to have the same source, of course (I can't help you there).   Take note that the Mini-X offers a buffered pass-through (RCA output jacks) that can be used as input to another amp.

 

----

 

 

 

http://www.amazon.com/Scosche-SPL1000F-135DB-Max-Meter/dp/B001CMKFH8

 

I'll also send you this cheap SPL meter.  Even if it's inaccurate in terms of measured SPL, it's easy to tell that it is at least consistent - making it perfectly acceptable for level-matching, just by inserting it between the ear pads as you switch between components while playing a white noise WAV file.  Playing the white noise file with the headphones on a table top and SPL meter sandwiched between the ear pads, it only takes me about 30 seconds to level-match two amps.  Hint:  For the Soloist, with it's stepped attenuator, start by setting its volume first - to roughly 85 db or thereabouts, then use the continuous gain control of another amp to match whatever you measured with the Soloist.

 

-----

 

http://home.globalcrossing.net/~zilch0/images/Bink_Audio_WAV_Files.zip

 

Lastly, here's a set of Bink Audio test files (free) that you (anyone) can download from my server.  The white noise file is accompanied by some files that cover the bass and treble frequencies (for testing extension). 

 

Thanks,

 

Mike


Edited by zilch0md - 7/1/13 at 5:39am
post #328 of 2631
Gary, the energies are much higher than audio range. It's removing as much as possible of anything above 60~ that allows the power supply to be more efficient. Typically the improvements are in dynamics, quieter background and improved transparency of the signal (particularly low end). Improvements are most noticed in power amps but it also has an impact on converters. The micro details that live near the noise level are typically masked. When the noise level is lowered, those details become exposed.

The better gear that can resolve the minute details will benefit most by this filtering.

IMO
post #329 of 2631

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

post #330 of 2631
Quote:
Originally Posted by Gary in MD View Post

 

Anybody who has suggestions on other ways of doing the comparison, or other things they'd like to work into the process, just let me know.  I'm open to any ideas you might have.

 

Gary

 

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. 

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