# Gauging Interest: The 1st Annual "Amps Sound the Same?" Class A/B , Class D Challenge.



## Old'sCool (May 16, 2021)

What: A listening contest designed to test your ability to differentiate between Class A/B and Class D amplifiers accurately, and to provide your preference.

Where: NC State Fairgrounds, Raleigh, NC, Prince William Fairgrounds, Northern VA, or Georgia State Fairgrounds, Hampton, GA, or somewhere else on East coast , perhaps an audio shop. (To be decided by entrants).

Who: Up to 25 nerds, geeks, dudes, dudettes and milfs, sharing a similar interest. (Super sweet car audio.)

Why: To settle the controversial topic of Class A/B vs Class D, and whether one can REPEATEDLY and ACCURATELY differentiate the sonic signatures of each.

When: TBD, Fall 2021.

How: A one-seater test "vehicle" will be constructed, containing a head unit and a stereo pair of woofers, midranges and tweeters, *with the "driver seat" centered between both* (figure A).

Utilizing an instantaneous switchboard apparatus, listeners will be allowed to pick up to 3 reference songs of their choosing, on Compact Disc format, and audition each amplifier for several cycles. (You will be required to bring your own discs.)

Each listener will be required to tell the admin when they are prepared, select their test track(s) and begin.

Each listener has 10 "cycles" to listen.

Each cycle will be timed at one minute and thirty seconds, during which time, the user may request the amps be switched as few or as many times as they wish, meaning they may listen to amp A or B for alternating cycles of 1:30, or, may listen to both, on and off, as often as the listener sees fit.

The amps will ONLY be identified as AMP A and AMP B until the testing for the day has concluded, at which point, the admins will tally the accuracy of each listener and give each person a percentage score. (Edit/Note: I realize this part has caused some confusion - AMP A will not be Amp A the whole ten cycles, but the end result will note which it was EACH cycle, and the preference between each [if any] will be noted not as A or B, but rather which class the participants chose.)

A neutral administrator and an auditor/record keeper will be employed to operate the switchboard, spreadsheets, and call "time," and ask the listener which sounds "better or worse" to them. Listener must choose their preference after each change is completed and they've heard both amplifiers. (As many as two cycles, or as few as one, dependant on listener's pref.)

The amps MUST be switched back and forth each time the listener requests it, without any trickery or attempt to keep one amp on/not switch when asked.

Admins will begin each cycle by saying "AMP A," and will be required to call out "AMP B," when the amps are switched.
(Amp A and B applies discretely to EACH cycle, meaning the Admin team may choose which amp is A or B for that particular cycle. Admin are NOT required to change A and B between each cycle, but they must keep accurate data as to which amp was A or B from said cycle.

(This is intended to prevent arguments about psychoacoustics, since the admins will have the data regarding preference, and there can be no fudging of those numbers. Likewise, there will be a switch each time requested, so the listener only knows the amps were switched, and NOT what design the amp is.)

"Accuracy" will be gauged as each listener's ability to "prefer" the same amp repeatedly and accurately. Highest accuracy wins this event.

At the conclusion, a cash prize and other possible gear will be awarded to the top listener/listeners in event of a tie. (Or perhaps, winner keeps both test amplifiers, etc.)

Scores from listeners with greater than 70% accuracy will be tallied, so the overall preference of "which sounded better" to the group can be objectively measured.

Entry Cost: $55 each, not including meals, etc.

Prize: Depending on number of entrants. $10/contestant will be pooled to create the prize, and the remainder used to cover costs associated with construction of the test vehicle and other expenses.

Manufacturers and shops are encouraged to sponsor and or host this event, and any media outlets or stereo bloggers, etc., may attend to document the contest. It's an all-day gig, so perhaps other fun events could be added to quell boredom for those testing later in the day.

Please respond to this thread with a "I wish to enter, and prefer 'X' location.

You may also reply with "I wish to sponsor this event by providing (prize, hosting, location, equipment, etc.).

*This would be a DAMN good time for a Class D amp maker to provide their best gear,* since the point is to settle the overall preference between A/B and D amps, as well as settle the decades-old argument that "an amp is an amp."


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## Old'sCool (May 16, 2021)

I wish to attend and help sponsor.

I am willing to provide: cables.

My preferred location is: NC State Fairgrounds, indoors.


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## vactor (Oct 27, 2005)

what are you challenging people to do? tell that each amp is different? 
""Accuracy" will be gauged as each listener's ability to "prefer" the same amp repeatedly and accurately. Highest accuracy wins this event. "
-isn't the administrator telling them that the amps are different? "this is amp A". doesn't the subject just then say "i like amp A more" each time they are told they are listening to amp A?
-how are the amps set up? if the output / gain levels are not matched, then each amp will sound different based on the ratio of input gain versus output power and distortion, so one amp will very likely be louder and / or more or less distorted, unless those are controlled for ... ??


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## dumdum (Feb 27, 2007)

Not having it random (always a after b) kinda defeats the point, you can then listen for commonalitys and differences between the two, there are abx switchers for just this purpose

will both be equalised to the exact same phase and amplitude alignment? They should otherwise it’s just which amp do you prefer the sound of… you could have a good class ab and an awful class d. Who decides what is good enough to be on both sides of the fence? Im in the U.K. so I’mnot involved anyway, but it will be interesting, but more conditions need applying to make it relevant


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## Old'sCool (May 16, 2021)

vactor said:


> what are you challenging people to do? tell that each amp is different?
> ""Accuracy" will be gauged as each listener's ability to "prefer" the same amp repeatedly and accurately. Highest accuracy wins this event. "
> -isn't the administrator telling them that the amps are different? "this is amp A". doesn't the subject just then say "i like amp A more" each time they are told they are listening to amp A?
> -how are the amps set up? if the output / gain levels are not matched, then each amp will sound different based on the ratio of input gain versus output power and distortion, so one amp will very likely be louder and / or more or less distorted, unless those are controlled for ... ??


Amp A and B are only required to remain the same EACH DISCRETE CYCLE. In other words, for the 1st 1:30 Amp A and B are the same , and can be switched, at the admin's discretion, for each successive cycle. I.E., amp A from cycle 1 may be amp B on cycle two, or it may still be amp A from cycle 1. Only the Admin know which is which, and they cannot tell the listeners anything but "Amp A." or "Amp B."

I know how gains and matching work. So will the experts who help build the test platform. They will both be optimized prior to the challenge, and there will ONLY be switching between the amps in real time. No breaks.

Again, Amp A for each cycle will not necessarily be amp A from the prior...


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## Old'sCool (May 16, 2021)

dumdum said:


> Not having it random (always a after b) kinda defeats the point, you can then listen for commonalitys and differences between the two, there are abx switchers for just this purpose
> 
> will both be equalised to the exact same phase and amplitude alignment? They should otherwise it’s just which amp do you prefer the sound of… you could have a good class ab and an awful class d. Who decides what is good enough to be on both sides of the fence? Im in the U.K. so I’mnot involved anyway, but it will be interesting, but more conditions need applying to make it relevant


See answer to A vs B above.

The amps will be on a switcher.

There will be NO need for time alignment. The listener will be seated DIRECTLY centered in the "vehicle."


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## Old'sCool (May 16, 2021)

Also...please read the main post. Nobody plans to pick a crappy Class D amp or A/B amp.

I would like the BEST Class D the D fan boys can pick, be it Helix or Heaven-sent. 

I wish to select the Class A/B used, but it can be provided by a third party, new in box, to prevent accusations.

It shouldn't matter if I select a $3000 Zapco or a $500 Polk, as long as the Class D camp is satisfied their choice is cream-of-the-crop.


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## Old'sCool (May 16, 2021)

Sick of the but-but-but. Nobody is trying to pull a fast one or select some crazy amp with a huge rolloff or other "flaw" that would render it easily recognisable.

This test is going to be performed as fairly as possible, or it will NOT be performed.

I am certainly wanting input on improvements to the test process, as I'm not a scientist or lab rat - I'm a blue-collar audiophile who is up to taking on the listening challenge.

That said, there will be ZERO DSP or time manipulation, as these are in the DIGITAL realm. Once the signal leaves the Head unit's DAC and travels through the RCAs, it is ONLY to be manipulated via gain matching at each amp.

Measurements can also be taken to ensure any difference in overall SPL can be accounted for via the volume control ON the head unit. Only the volume, and track and NOT the tone controls, may be manipulated during testing.


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## vactor (Oct 27, 2005)

so the volume control can be used, or will there be a set listening level that is a control level (such as 85db at listening position and normalized for each amp in question?)


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## Old'sCool (May 16, 2021)

vactor said:


> so the volume control can be used, or will there be a set listening level that is a control level (such as 85db at listening position and normalized for each amp in question?)


I will leave that to the scientists, but I do like a cap on overall volume @ listener.


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## Cutaway (May 5, 2020)

This is a super fun experiment as a few of us from the "other board" got together a few weekends ago and did this... We would grab two amps, set them to play at the same SPL output and sat on a couch with an ABX switcher in hand. We ran a few different amps and were doing this just for fun. This was not designed to say Amp A is "better" then B, it was to determine if we could hear the difference. One person in the test got a 10/10 and the rest of us averaged > 5/10

If this can actually gain traction i would be down to help out in one way or another...


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## rton20s (Feb 14, 2011)




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## CCole (Sep 9, 2020)

This might be something to coordinate with one of the SQ competition governing bodies to do at their show. There always looking to try something new. It might be difficult to get people to travel any distance when most own the gear to do this at home. Just a thought. 
Definitely interested in the results!


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## Old'sCool (May 16, 2021)

All talk, eh?

Just can't win.

If you think I'm all talk, you've got me 100% wrong.

I am putting this out there to make it happen. I'm not posting memes and pulling my pud...

I really do like the idea of involving say, IASCA, but I'd rather have a few major sponsors, and an event unto its own.

If class D is as great as all the fan boys keep pontificating, PICK your choice of Class D amps. Contact the manufacturer or distributor, and get them to provide a sample amp (or better yet, pick one and we order it via group funding, to ensure it's Actually class D, and no shenanigans).

If people are gonna cry foul at my choosing the Class A/B, or claim it can be altered or manipulated by me, then I will merely chose the amp and we can order it NIB, too.

Suffice it to say, I don't have $2000-$3000 in spare change to purchase my preferred amp(s), so, the only skin I really have in this is my ability to say, "I effing told you so."

Sounds good. IS GONNA HAPPEN. If you don't want to partake in reasonable discourse, please don't partake in the thread, either.

- O.C.


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## Alex C (May 19, 2021)

Ive never been to an SQ event or really an event in general. This seems like a very interesting event to attend to though. Preferred location is VA or more north!


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## Old'sCool (May 16, 2021)

CCole said:


> This might be something to coordinate with one of the SQ competition governing bodies to do at their show. There always looking to try something new. It might be difficult to get people to travel any distance when most own the gear to do this at home. Just a thought.
> Definitely interested in the results!


I don't know too many people who have the ability to do an A/B switch at home without the sound being stopped/started. I believe it requires a special switchboard, especially when only one set of loudspeakers/xovers/cables will be used.


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## MrToadsWildRide (Jun 10, 2021)

The original test was an A/B/X switch. X was randomly A or B, it was your job to determine which. One way to do the test would be: You choose 1 track. Listen to the 1st minute of the track on Amp A, repeat for Amp B, repeat for Amp X (admin chooses A or B for X), then you decide if X was A or B.


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## ca90ss (Jul 2, 2005)

Old'sCool said:


> What: A listening contest designed to test your ability to differentiate between Class A/B and Class D amplifiers accurately and to provide your preference


Seems like that would take two separate tests. One to determine if people could tell a difference between classes and one to pick a favorite of the group.


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## Holmz (Jul 12, 2017)

Old'sCool said:


> ...
> My preferred location is: NC State Fairgrounds, indoors.


 A church would be more appropriate...


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## Old'sCool (May 16, 2021)

Holmz said:


> A church would be more appropriate...


Not sure I follow?


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## Old'sCool (May 16, 2021)

MrToadsWildRide said:


> The original test was an A/B/X switch. X was randomly A or B, it was your job to determine which. One way to do the test would be: You choose 1 track. Listen to the 1st minute of the track on Amp A, repeat for Amp B, repeat for Amp X (admin chooses A or B for X), then you decide if X was A or B.


Interesting. I like this.

I think the admins could accomplish the same, but not in a true random fashion.

With just AB, if someone picks THE SAME amp 10/10 times, as "This sounds better to me," then the data show they picked the class D, Class D gets 10 points overall in the final tally of who preferred what.

As long as A and B don't remain the original "A and B" for each cycle, I can't see how a listener would know which was which unless they preferred a particular amp's sound from the two.

Everyone has different ears. Some are happy with piezos mounted in their sail panels, while others can't even listen to a tweeter that's not silk. Some prefer a very forward sound, while others like a laid-back presentation.

Here's another, far easier test, which we used to evaluate home amps and speakers. A "true blind."

Two identical systems are set up in two identical "vehicles." The overall output is capped at, say 109dB, and can be attenuated or increased by the listeners up to the preselected max volume.

NOBODY except the installer/tuner knows which amp is in which "vehicle."

Each listener has a set time to listen to three preselected test tracks in each car, perhaps 5 to 6 minutes, and each listener takes notes as to what they hear, i.e.:

"In vehicle A, the cymbals on Van Halen's, 'Panama' sounded overly forward/bright. The vocals on Clair Marlo's 'All for the feeling' were quite nasal, and the image was vague on her voice. On Mickey Hart, 'Jewe,' the sounds of the background singers had little to no defined space in the stage, but the quality of the overall sound was pleasing."

"In vehicle B, the cymbals on 'Panama' had a natural, pleasing and realistic metallic sound. On Clair Marlo, 'All for the Feeling,' her voice sounded perfect, and had a clear center image. The background singers in 'Jewe' were all clearly defined in space, and I could pinpoint each of their mouths, as well as the sounds of their fists beating on their chests, without closing my eyes or straining to hear them. The overall sound was more pleasing, and the vehicle's staging and imaging were nearly perfect. I prefer vehicle B."

Once the listeners all complete the test, WITHOUT comparing notes, the data can be presented, and they are shown which amp they preferred.

This is less of a contest and more of a blind equipment comparison. That said, THIS would reveal how many listeners prefer Class A/B vs Class D.

The neat part about this is, you'd be quite surprised how many seasoned listeners/audiophiles will make similar notes on their cards.


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## Isaradia (Apr 14, 2020)

1 vote for ga. one concern i do have is id prefer both amps eq'd to as near the same curve as possible, so it's about a/b vs d, not this specific amp out of the box vs this specific amp out of the box


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## Catalyx (Oct 13, 2011)

I have a variety of high end amps and a QSC Audio ABX Comparator to lend. Check out the manual for details to see if it would work for your test:

http://ackthud.com/shawnfogg/pics/temp/ABX_manual.pdf


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## Old'sCool (May 16, 2021)

Isaradia said:


> 1 vote for ga. one concern i do have is id prefer both amps eq'd to as near the same curve as possible, so it's about a/b vs d, not this specific amp out of the box vs this specific amp out of the box


Only gripe I have with EQing is, the "digititis" that bugs me with Class D amps could (possibly) be attenuated. Probably not, though. 

Maybe a head unit with parametric EQ could be employed, just to bring the curves as close as possible, but then you get in to having to have 2 custom curves set, if you're really trying to match the outputs of the amps.

I am going to sleep on some more ideas. I really want to make the challenge...well...challenging. What's the fun if it's easy.

Since we're attempting to listen to the amps themselves, as long as the EQ is pre-output stage on the HU, I would not be as put off by the idea, aside from extra complexity when switching amps.

I think GA might get some votes! Then again, half the responses so far are unfavorable...lmao.


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## Old'sCool (May 16, 2021)

Catalyx said:


> I have a variety of high end amps and a QSC Audio ABX Comparator to lend. Check out the manual for details to see if it would work for your test:
> 
> http://ackthud.com/shawnfogg/pics/temp/ABX_manual.pdf


Thank you! I'll give it a read tomorrow for sure!


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## Catalyx (Oct 13, 2011)

After you’re done reading that, put aside some hours to peruse the thread for Nick’s amp test that addressed a lot of technical factors to consider:

Thinking about doing a blind subjective and measured...


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## Holmz (Jul 12, 2017)

Old'sCool said:


> Not sure I follow?


The idea of confirmation bias, psychoaccoustics, and the magicalness of the amplifiers.


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## Old'sCool (May 16, 2021)

Holmz said:


> The idea of confirmation bias, psychoaccoustics, and the magicalness of the amplifiers.


Never said amps are "magical." I said I can hear the difference(s).

Cannot imagine a cat with 6000+ posts has never heard an amp that gave him shivers, vs one that made him cringe.

Great example would be to go to a high end home audio shop (or come sit in my listening room) and audition a pair of humble Rega Jura towers playing via a great amp and a mediocre one.

(It might sound like a very subjective outcome, but if you cannot hear the difference between a Moon Audio P7 and an Onkyo amp, well...GOOD FOR YOU! You'll save SO MUCH money in your life not having to upgrade your amps, etc.)


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## EricsAmplifiers (May 30, 2021)

I would love to attend provided I can make it! If I do, I’ll bring what I consider personally are my best of the best sounding old school Class A/AB amps IMO. I’ll bring the butter if someone else toasts the bread!

Old school amps will be allowed?

level matching will need to be normalized.IE; a 100x2 watt amp will need to play as loud as a 350x2 watt amp otherwise volume will be an upset for the smaller amps. You know?


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## Old'sCool (May 16, 2021)

EricsAmplifiers said:


> I would love to attend provided I can make it! If I do, I’ll bring what I consider personally are my best of the best sounding old school Class A/AB amps IMO. I’ll bring the butter if someone else toasts the bread!
> 
> Old school amps will be allowed?
> 
> level matching will need to be normalized.IE; a 100x2 watt amp will need to play as loud as a 350x2 watt amp otherwise volume will be an upset for the smaller amps. You know?


I'm game for Old School amps. I mean...They literally don't make em like they used to.


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## MrToadsWildRide (Jun 10, 2021)

Isaradia said:


> 1 vote for ga. one concern i do have is id prefer both amps eq'd to as near the same curve as possible, so it's about a/b vs d, not this specific amp out of the box vs this specific amp out of the box


I think it should be an "out of the box" test. To me, the amp that required the least amount of EQ to sound correct should be the winner.



Old'sCool said:


> Never said amps are "magical." I said I can hear the difference(s).


Amps may sound different, I just believe that it's easier to hear the difference between a $200 component set and a $500 component set than it is to hear the difference between a $200 amp and a $500 amp.


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## JCsAudio (Jun 16, 2014)

Not all amps clip the same! Will definitely need to take that into consideration when listening at louder volumes.


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## Catalyx (Oct 13, 2011)

I would avoid using EQ or any other manipulation of sound before amplification if possible. Anything required should be done early in the chain to ensure identical signals are delivered to each gain matched amp for a level playing field.


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## dumdum (Feb 27, 2007)

Catalyx said:


> I would avoid using EQ or any other manipulation of sound before amplification if possible. Anything required should be done early in the chain to ensure identical signals are delivered to each gain matched amp for a level playing field.


But then it’s just the amp in questions response vs the other amps response, not the actual amplifier class, not really a test as one may suit the load and drivers, with different drivers the outcome may be different, not really a test of anything other than what combination compliments each other the best


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## Catalyx (Oct 13, 2011)

Wait, you mean all amps don’t sound the same? ;-)


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## Catalyx (Oct 13, 2011)

If you use top quality amps from each class and manipulate the signals to even curves I would bet big money that people won’t hear the difference.


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## Holmz (Jul 12, 2017)

Old'sCool said:


> Never said amps are "magical." I said I can hear the difference(s).
> 
> Cannot imagine a cat with 6000+ posts has never heard an amp that gave him shivers, vs one that made him cringe.
> 
> ...


A lot of that magic is tied up in difficult to drive speakers.
High inductance, low impedence, and inefficient speakers pose a challenge.
Add to that high SPL and it gets hard.

In the home I only upgrade mollified a when they fail.
In the car I just go for for good amps, so I do not have a compelling reason to want to upgrade them.
At some point it is good to listen to the music, and once the amplifier is not apparent, then the job is done.


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## jtrosky (Jul 19, 2019)

dumdum said:


> But then it’s just the amp in questions response vs the other amps response, not the actual amplifier class, not really a test as one may suit the load and drivers, with different drivers the outcome may be different, not really a test of anything other than what combination compliments each other the best


This...

Unless you have two of the exact same amps, one using class-A/B amplification and one using class-D amplification, then you really aren't comparing one amp "class" to another. You are comparing one amp to another, which is not the goal here. There is more to an amp that it's "class". 

I mean if a $7000 class-D amp sounds better than a $40 class a/b amp, does that mean that class D amplification is "better"? Of course not. There are lots of component inside an amp that form to make a complete amplifier. 

Unfortunately, I'm not aware of anyone that makes the exact same amp with two different classes of amplification...


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## Catalyx (Oct 13, 2011)

jtrosky said:


> Unfortunately, I'm not aware of anyone that makes the exact same amp with two different classes of amplification...


Maybe a hybrid amp with class a/b and full range class d channels to at least keep the signal within one board but I don't know if any are made.


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## Holmz (Jul 12, 2017)

Catalyx said:


> Maybe a hybrid amp with class a/b and full range class d channels to at least keep the signal within one board but I don't know if any are made.


One can always run tweeters and mids on A, or A/B and MB on class D... there is not a law precluding that... yet.


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## Catalyx (Oct 13, 2011)

Holmz said:


> One can always run tweeters and mids on A, or A/B and MB on class D... there is not a law precluding that... yet.


The point would be to gain match a pair of A/B channels with a pair of full range D on this theoretical amp then switch between them on the same speakers for comparison of class type.


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## Holmz (Jul 12, 2017)

Yeah... I forgot.


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## Old'sCool (May 16, 2021)

Catalyx said:


> If you use top quality amps from each class and manipulate the signals to even curves I would bet big money that people won’t hear the difference.


I bet many cannot.


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## Old'sCool (May 16, 2021)

Holmz said:


> One can always run tweeters and mids on A, or A/B and MB on class D... there is not a law precluding that... yet.


This is how my last 2 personal builds are set up. (And my current build will be.)

Class D's "fingerprint" isn't evident to me below midrange freqs.

15 years ago, I wasn't impressed with anything D amps had to offer, except massive power for subs, and low current draw.


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## dumdum (Feb 27, 2007)

Listen to a hypex class d, it is likely one of the purest ‘Wires with gain’ that you can hear, but some people still won’t like the lack of distortion/harmonics that are created by some amps, what sounds best is subjective, what you prefer is subjective, can you tell them apart is also down to the amp, this is why you need amplitude with eq and phase to be matched and then listen and see what differences if any can be heard…

your ‘method’ just proves that Amps have character and a sound


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## Old'sCool (May 16, 2021)

Subjectivity can play a huge role in perceived SQ and "enjoyability." The best amp, cable, speaker, etc. is one which leaves no sonic signature.

If you hop in my favorite car and crank the system, it sounds the same at high volume as at low volume. That's my ultimate goal when I build a system. 

I like to be able to hear the whole recording perfectly, whether parked/cruising with the volume at 10, or on the interstate with it cranked to 35+.

Every component I select (and it can take me MONTHS to select them all) is picked for neutrality/low noise/clarity. Price usually, but not always, plays a factor. 

Sometimes I'm pleasantly shocked by a cheap item, such as the KAPPA 1200W subs. They have plenty of output when asked, but at low volumes, I'm still not missing the detail and impact of the deepest octaves. 

Sometimes, I'm unimpressed by a high-ticket item, like the current JL 12s. They're good but NOT "whole paycheck good."



The answers and comments to my proposal for an A/B vs D shootout thus far remind me of a 2018 "Stereophile" article discussing what stereo imaging "means and sounds like." The article references Julian Hirsch's 1979 article in "Stereo Review," and the big takeaway is, nobody hears a stereo image exactly the same. I.E., much of imaging (and sound quality) is subjective.

It also argues that the quest for a seamless, perfect sound stage is less important than overall "pleasing sound" and enjoyment of the music. I can certainly see both sides of that argument. 

At what point can the listener(s) merely press "Play," and sit back to relax/feel the spirit of the sound? Does a system need to be so surgically precise, that only a flawless recording is listenable? Does it need a natural softness, like a tube amp or paper cone tweeter, to attenuate excessive distortion in certain songs? Well...who's to say? Only your ears know what your ears love.

To myself, I require fidelity, range, and precision. The best imaging, to my ears, is only apparent when I'm able to differentiate each instrument's individual sound, each singer's spot on the stage (if the recording allows), and each note layered perfectly, none muddying another.


It's really excellent article:









The Stereo Image


The author demonstrating stereo microphone techniques at an English audio show in 1981.




www.stereophile.com





Perhaps for this challenge there should be a price window for each amplifier. Say, 500-750 or 750-1000 per 2ch amplifier.

Using two channels with passive 3-way crossovers also presents another challenge: one amp may prefer the load presented by the crossovers, while the other may struggle.

If I recall, Zapco makes Class AB and Class D full-range amps in their studio line. Perhaps a same brand shootout would be more productive? Assuming the designer(s) had the same intent with both amps (clearly, accurately and quietly boost a signal/sine wave), using both classes from one manufacturer might provide fewer pitfalls.

*I appreciate both the positive and critical input so far! If we can all agree that no four ears are alike, we are all on the same page when we sit to nitpick and/or enjoy the amps.*


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## captainobvious (Mar 11, 2006)

You may want to look up the thread I did on this like 8-10 years ago. It is very important to eliminate as many variables as possible. Things to consider:
-you need immediate switching
-you should consider doing an AX test instead of an ABX. It is simpler and should be even easier to identify differences. The AX compares a reference (A amp) to a single unknown (X). It requires no aural memory of an additional B amp. You play the A sample, then you Switch immediately to either the X or the A again (controlled by admin). Each time, the listener writes down if they think the X is the same A amp or if it is different (X). Same or different- doesn’t get any easier than that, right? Do it multiple times.
-In order for your test to be statistically significant, you need a lot of data. Doing this with 2 amps and 4 people will not yield you significant results.

My testing years ago i had like 8 different amps- class A/B, D, etc. Old, new, cheap/expensive. I rented a hotel conference room and set up Martin Logan electrostatic home towers as the speakers. I used mechanical switcher boxes, the same cables/type/length, level matched amps, etc.
Then, i recorded all the data over the session.


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## Holmz (Jul 12, 2017)

Old'sCool said:


> ...
> Perhaps for this challenge there should be a price window for each amplifier. Say, 500-750 or 750-1000 per 2ch amplifier.
> *...*


^Why^?

Not every aspect of DIY is about saving a sheckle.
One could have a range of price points, but some people actually buy expensive low distortion amplifiers. And they go out of their way intentionally to seek out those unicorn pieces.


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## Old'sCool (May 16, 2021)

Holmz said:


> ^Why^?
> 
> Not every aspect of DIY is about saving a sheckle.
> One could have a range of price points, but some people actually buy expensive low distortion amplifiers. And they go out of their way intentionally to seek out those unicorn pieces.


Because we have people crying that a $200 Class D can't hang with a $1000 A/B.

I'm not saying we have to have a "limit." I'm saying a price window for the comparison amps.

If we throw a $2500 Class D against a $129 A/B Crunch, it'll be a short experiment...


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## Old'sCool (May 16, 2021)

captainobvious said:


> You may want to look up the thread I did on this like 8-10 years ago. It is very important to eliminate as many variables as possible. Things to consider:
> -you need immediate switching
> -you should consider doing an AX test instead of an ABX. It is simpler and should be even easier to identify differences. The AX compares a reference (A amp) to a single unknown (X). It requires no aural memory of an additional B amp. You play the A sample, then you Switch immediately to either the X or the A again (controlled by admin). Each time, the listener writes down if they think the X is the same A amp or if it is different (X). Same or different- doesn’t get any easier than that, right? Do it multiple times.
> -In order for your test to be statistically significant, you need a lot of data. Doing this with 2 amps and 4 people will not yield you significant results.
> ...


A hotel conference room could be okay. Axpona shows are set up at conference centers, and I've auditioned some impressive setups there.


I just so happen to have a set of electrostats. 

I prefer an A_B comparison to ABX for this shootout. 

A reference amp doesn't seem fit in this test, as I'm gearing towards A/B vs D. 

I'm game to have the best two amps we can procure, head to head. 

My 'stats have their own subwoofer amplifier and crossover, however, so the bass would be identical on A and B car amp.

Speakers are available, whether 'stats or traditional, so that's not an issue.

There are several factors that could influence the outcome. 

Yes, the plan is to use instantaneous switching.


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## captainobvious (Mar 11, 2006)

First- you need to determine IF you can hear a difference between amps period. Did you read my thread and the data included to see how the experiment was run?

The whole idea behind an AX test is to determine if you can consistently detect a difference in sound between 2 amplifiers. You’re switching from one amplifier to the other instantaneously- OR to the same amp , the point is that you don’t know when switching if it’s the second amp or the same amp- UNLESS you can hear a difference, repeatedly and consistently. The two amps can be A/B and D... or similar A/B...whatever. Like I said in my testing I did MULTIPLE runs of AX comparison. With each new sheet we compared a new amplifier and an unknown. The switching would occur and Listeners were asked to indicate on their sheets Whether they were hearing the same amp or a different amp. Each time, they would hear 15 seconds or so of the Known “reference” amplifier, then the switcher was engaged and they were hearing 15 seconds of either the same reference amplifier or the unknown different amp, and had to indicate if they were hearing the same amp or the different one.

Reading the thread and the data I posted will probably give you a good starting point.

Again though, the reason for not doing an AB or ABX is because you are asking listeners to listen, remember The sound between 2 amps and then identify which is playing (ABX). The AX is simply determining if the sound you are hearing is the same...or different. It’s a much easier experiment. It comes from the position of “Can I hear a difference at all, consistently?” I think it’s important to understand that before trying to identify “Which sounds better?”

That said, you can run your experiment any way you choose, but if you want the results to be meaningful from a data perspective, you need to have a real defined plan, controls, eliminate variables, consistent and reliable data collection and enough results that the data tells you something statistically significant if you want to draw any concrete conclusions from it.


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## captainobvious (Mar 11, 2006)

Post number 216 shows the results (Link to thread below). In the attachments you’ll find the AX comparison, the NON-blind comparison (we did both), and the write up on the test parameters.









A/B Blind tests on amplifiers- Time to hear for myself


"The Goal" I have a little pile of amplifiers at my disposal(some A/B, some class D, some large, some small, some old and some new, and some expensive, some middle of the road) and I want to determine first if I CAN hear a difference between them, and then, which I prefer and for what reasons...




www.diymobileaudio.com


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## Holmz (Jul 12, 2017)

captainobvious said:


> Post number 216 shows the results (Link to thread below). In the attachments you’ll find the AX comparison, the NON-blind comparison (we did both), and the write up on the test parameters.
> 
> 
> 
> ...


It seems wise to use the last test as a way forward to the next one.


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## MrToadsWildRide (Jun 10, 2021)

I don't think people can hear the difference. Part of the reason I believe this is because for many years I've watched competitors swap equipment on a regular basis and still get the same result. I'm willing to bet that the reason this is possible is because the application and tuning of a product is more important than the product itself.


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## JCsAudio (Jun 16, 2014)

captainobvious said:


> Post number 216 shows the results (Link to thread below). In the attachments you’ll find the AX comparison, the NON-blind comparison (we did both), and the write up on the test parameters.
> 
> 
> 
> ...


I'm going to read this as soon as I have the time. 

Thanks


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## Old'sCool (May 16, 2021)

captainobvious said:


> First- you need to determine IF you can hear a difference between amps period. Did you read my thread and the data included to see how the experiment was run?
> 
> The whole idea behind an AX test is to determine if you can consistently detect a difference in sound between 2 amplifiers. You’re switching from one amplifier to the other instantaneously- OR to the same amp , the point is that you don’t know when switching if it’s the second amp or the same amp- UNLESS you can hear a difference, repeatedly and consistently. The two amps can be A/B and D... or similar A/B...whatever. Like I said in my testing I did MULTIPLE runs of AX comparison. With each new sheet we compared a new amplifier and an unknown. The switching would occur and Listeners were asked to indicate on their sheets Whether they were hearing the same amp or a different amp. Each time, they would hear 15 seconds or so of the Known “reference” amplifier, then the switcher was engaged and they were hearing 15 seconds of either the same reference amplifier or the unknown different amp, and had to indicate if they were hearing the same amp or the different one.
> 
> ...


I can hear the difference(s) between (most) amps.

I believe I was the 1st person in the other thread to accept the wager that I could.

I can also dig the requirement for a control in a scientific experiment. Believe it or not, I have two degrees and several vocational certs., to boot.

This isn't a scientific experiment. It is intended to be a "challenge."

I say, Class D, while vastly improved since its inception, STILL sounds like garbage compared to even a decent A/B amp.

I can literally sit in my car with a class D amp running mids/tweeters and hear digital artifacts from the amps. I know it is not from the source, as when I swap-in even a humble Kicker 50x2 A/B amp that's 15 yrs old, the "Star Wars" sound goes away, and I can hear cymbals and whispers naturally decay into silence, feet on piano pedals, saliva and teeth smacking, etc. - the little stuff most people drop-jaw over the 1st time they strap a great pair of headphones on.

With Class D amps, even ones I was promised, "sound flawless," I can hear the same Star Wars effect...i.e., the cymbals, breaths, soft plucks of a mic'd nylon-strung guitar, etc., no longer sound analog, or more specifically, they sound "reproduced."

If I'm listening to Mick Jagger, I darn near better smell his breath. If I'm listening to Bela Fleck pluck his banjo, I want to "see" that banjo on the stage.

The best example I can provide?

The stand up bass on Bela Fleck "Perpetual Motion" CD sounds "okay" on Class D. You can ALMOST make out the body of the bass, vs the neck.

On class A/B, you hear the neck, the body, and even whether the instrumentalist is breathing through their nose or mouth.

On Class A, I can hear the body of the bass, the finger slaps, the neck, AND the bass coupling to the floor of the recording room. The bass is "there." It is a concrete, palpable thing - perfectly portrayed. At no time does it sound like reproduced music, or synthetic, whatsoever. There's no need to "squint," to hear nuances lost in lesser amps.

"Perpetual Motion" is one of the most incredible recordings I own. It is a bellwether when I tune a car by ear, especially one with no DSP.

I'm sure you have good ears, and I'm sure you have listened to a system that made you say, "Wow. I'm IN the studio." Class D (in my experience, at least) just hasn't gotten there.

Now, I must reiterate - I've not auditioned every Class D amp made. I'd LOVE to be proven wrong. Would I spend $2k on a Class D amp that could wow me like a $1000 A/B? Nope, probably not. Fortunately, I have YET to hear a single class D amplifier that had me trying to figure out what to sell so I could afford it.

Paul Simon's "Capeman" CD is another great example. On my Class A system at home, you can reach out and shake Paul's hand. On my class A/B system, you practically feel the same, but there is about 5% less "perfect," and 5% more "reproduced."

Unfortunately for me, I cannot accept less. In fact, I've only recently been able to tolerate Bluetooth, as it has finally gotten good enough to Xfer "lossless" or close enough that I can tolerate it.

I'm saying I can pick Class A/B out vs Digital 90% of the time, and the other 10, it's not due to my ears, but some other factor, like my kids or wife making noise downstairs, etc.

Call it a placebo if you wish, but then, please explain why the walls of the studio all but disappear with Class D? Why can't I hear the little things, and why did the background singer just become a voice, rather than a palpable THING on the stage?

I really have no predisposed bias against any amp topography; I'm sure Class D will one day be the norm, and A/B will be a dinosaur.

Today, unfortunately, I cannot hear the difference between a Class D Lanzar from Ebay, and a "high-end" D.

I don't need a scientific experiment to know when my ears are satisfactorily fooled into believing the sounds they hear are live instruments and full-bodied humans. All I need is a few songs I've used for decades, a clean pair of ears, and literally one minute.

When "it's right," I find it so relaxing, I've often been lulled to sleep by Paul Simon's "Rene and Georgette Magritte with Their Dog After the War." When it's not right, no manner of speaker relocating, attenuation, etc. can seem to make it "real."


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## captainobvious (Mar 11, 2006)

The "scientific experiment" is done precisely to eliminate bias, variables and errors. When people say "well I can swap X out of my car and Y in and I hear the difference", or simply state that they "know" they are hearing a difference, well....I guess they can believe what they want- and that's fine. But there is a reason why people use controls in experiments. There are reasons why doing what you just stated is not a conclusive or accurate way to gauge one's ability to "hear the differences". Biasing is a huge factor- which even my simple experiment years ago highlighted. Blind, controlled testing makes for a MUCH different end result in the data.
I'm not suggesting that you must do a properly controlled and setup experiment- heck you can do whatever you want- swap amps in and out of cars one at a time with obscure time frames, no controls and non-blind. People do that all the time. What I AM suggesting though, is that those sorts of approaches will just have you spinning your wheels and not learning much about what you (or the people involved) actually can hear or cannot hear and getting meaningful answers from your time and efforts.

I'll leave it at that. Best of luck and have a fun time!


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## Old'sCool (May 16, 2021)

captainobvious said:


> The "scientific experiment" is done precisely to eliminate bias, variables and errors. When people say "well I can swap X out of my car and Y in and I hear the difference", or simply state that they "know" they are hearing a difference, well....I guess they can believe what they want- and that's fine. But there is a reason why people use controls in experiments. There are reasons why doing what you just stated is not a conclusive or accurate way to gauge one's ability to "hear the differences". Biasing is a huge factor- which even my simple experiment years ago highlighted. Blind, controlled testing makes for a MUCH different end result in the data.
> I'm not suggesting that you must do a properly controlled and setup experiment- heck you can do whatever you want- swap amps in and out of cars one at a time with obscure time frames, no controls and non-blind. People do that all the time. What I AM suggesting though, is that those sorts of approaches will just have you spinning your wheels and not learning much about what you (or the people involved) actually can hear or cannot hear and getting meaningful answers from your time and efforts.
> 
> I'll leave it at that. Best of luck and have a fun time!


You have an IASCA championship under your belt, and as of yet, I do not. (Respect, by the way.) I can only assume you have some degree of critical listening under your belt, as well.

If both amplifiers are unknown to each participant, i.e., they aren't told which is Class D or Class A/B, where can the bias come in to play?

Would "I like this better" not soon be moot, should a listener choose D 50% of the time and A/B the other 50?

I do understand the need for empirical data. I've compiled boats full for non audio studies.

I just feel that a shootout (blind) cannot be corrupted by bias, unless there's another external variable. I fancy your input, and hope I am not offending you.

I'm also sure the mind can play tricks, and those can certainly influence testing.

My cell phone usually sits on a small table by the front door. When I get a notification, the bell "sounds" like it's on the table, sometimes even if it's five feet from me in the kitchen.

A guy in 0-250W "Novice" used to have a blacked-out front windshield and a bright red dot, dead center. It was quite effective at the steering perceived image of vocalists to the center. It was not a magic bullet, but I thought the concept was telling. Though his image was rather low, it was already well centered. SQ judges gave him near perfect scores every competition we went to.

No psychoacoustics seem to make my ears happy when swapping a "good" AB amp for a "good" class, D, and ironically, I find the "best" sounding D amp I own is a $34 bluetooth-capable Nobsound, using the AUX input, but ALMOST as much using the Bluetooth. In fact, due to the staggering price/performance ratio vs the $800 amp it replaced, the $800 amp was sold-off via Audiogon within weeks of trying the Nobsound (although, I must admit, a linear power supply worth 3x the amp was required to tame noise at the floor).

My only guess as to why that particular amp pleases my senses (notwithstanding the fact it costs less than Pizza for a family of four) is that the amp has something softening the distortion, or is just too low-powered to allow the distortion to be noticeable. I highly doubt there was a huge engineering budget for this little critter.


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## Old'sCool (May 16, 2021)

MrToadsWildRide said:


> I don't think people can hear the difference. Part of the reason I believe this is because for many years I've watched competitors swap equipment on a regular basis and still get the same result. I'm willing to bet that the reason this is possible is because the application and tuning of a product is more important than the product itself.


I never said I don't prefer a properly tuned Class D setup to a "shade tree" AB install.

Given the choice, I'll take a well done system of any type over a hack.

I managed some pretty stout SQ and RTA scores in my day with Hifonics amps, amps which some folks seemed to loathe (no idea why).

I don't wanna crap-up my own thread with my experiences alone, and I'm happy to see some VERY experienced folks chiming in. 

I may come off as a know it all, but I'm actually quite keen to hear other facts, ideas and opinions. I believe that's what makes a good forum/community.

Will I hang my head in shame if I cannot tell a great AB from a D? Heck no! I'll shake hands and admit I was wrong. 

I have not heard a $2000 class D, but I have heard a bunch of expensive ones, easily more costly than most of my AB amps.

I'm considering a blind AB vs D shootout, along with a "Heisenberg-grade" experiment now. Two birds, so to speak...


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## Old'sCool (May 16, 2021)

FYI, Kudos to the Cap'n on his test. Holy spreadsheets, batman.


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## Catalyx (Oct 13, 2011)

If the question is whether people can detect a difference between A/B and D I would use an AX comparison. If the question is which class sounds better I would use ABX but ideally with a group of those who performed best in the first AX test since they exhibit better aural discernment.

Having a first round that only allows something like the top 50-75% to pass on to the second would increase competitive interest for people who want to prove their ears.


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## captainobvious (Mar 11, 2006)

Old'sCool said:


> FYI, Kudos to the Cap'n on his test. Holy spreadsheets, batman.


Thanks sir. And I'm not one of those easily offended youngsters so no worries there 
Just trying to help save you some time and headache if you're going to go through all the effort to make this happen. It's a lot of work, time and expense and a pain in the butt (trust me!). 

I look forward to learning about the experience and the results though.

In my tests, I started off with the testing group examining all amps and getting to do non-blind comparisons. They formed opinions on the amps and their perceptions. Then we got into the meet of the blind comparisons after that. I even let them pick which amps they wanted to compare blind for some of the comparisons, and they figured it would be easy to discern the difference between (for example- the Soundstream reference A/B and the little Arc class D xdi) them. It was quite interesting.


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## Catalyx (Oct 13, 2011)

Old'sCool said:


> I have not heard a $2000 class D, but I have heard a bunch of expensive ones, easily more costly than most of my AB amps.


The only $2,000 class D amps without DSP included are 10K watt monsters used for SPL competiton. SQ amplifier design is still dominated by class A/B but that could be more from companies knowing it would be hard to market D as high end rather than an actual inability to make that class sound as good.


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## Old'sCool (May 16, 2021)

captainobvious said:


> Thanks sir. And I'm not one of those easily offended youngsters so no worries there
> Just trying to help save you some time and headache if you're going to go through all the effort to make this happen. It's a lot of work, time and expense and a pain in the butt (trust me!).
> 
> I look forward to learning about the experience and the results though.
> ...


I totally dig the psychology behind that. Basically exposes any prejudicial assessment based on perceived quality/value.

If you've never seen a Nobsound 50w amp, the opposite is true with it! When you open the box, you're like, "Ummmm...I hope the seller accepts returns!" Somehow, that little 6-oz piece of recycled Pabst cans and Beijing grab-bag parts manages to push an efficient set of towers with finesse that belies its provenance.










I do plan to keep part of the shootout AB vs D, but a controlled experiment also seems in order.


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## Old'sCool (May 16, 2021)

Catalyx said:


> The only $2,000 class D amps without DSP included are 10K watt monsters used for SPL competiton. SQ amplifier design is still dominated by class A/B but that could be more from companies knowing it would be hard to market D as high end rather than an actual inability to make that class sound as good.


Don't get me wrong; there are some pretty crap AB amps on today's mkt.

The Infinity Class D full range stuff is not terrible. In fact, I recommend the kappa 4 and kappa 5 to folks looking for a small footprint and plenty of power/versatility. I also like the way the Kappa One K I sold my partner is handling his "new" stroker.

His van has all Infinity everything, aside from the CV sub and Xover. Three Kappa amps, all Class D. Two sets of Perfect 6.0 and a pair of perfect 3 mids. For the budget he had, it is very respectable. (I would love to slap a 4ch Zapco on the 3" mids and the Perfect tweeters, however.) They seem quite revealing and smooth, even Class D.


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## EricsAmplifiers (May 30, 2021)

If this does happen, I’d like to bring a ‘heater’ that will tickle yours ears. Perhaps after the amp works hard for your sonic pleasure we can then fry up an egg on it.

Perfection takes a lot of hard work is what I’m trying to say.

I bet you’ll throw all class dirty amps in a ditch and think twice about fidelity audio afterward.

“listening tests remain valuable and electrical measurements alone do not fully characterize the sound of an amplifier.” Quote from Nelson Pass


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## Patriot83 (May 10, 2017)

[QUOTE="EricsAmplifiers, post: 5941503, member: 226249
*“listening tests remain valuable and electrical measurements alone do not fully characterize the sound of an amplifier.” Quote from Nelson Pass*
[/QUOTE]
Bingo


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## Holmz (Jul 12, 2017)

Patriot83 said:


> [QUOTE="EricsAmplifiers, post: 5941503, member: 226249
> *“listening tests remain valuable and electrical measurements alone do not fully characterize the sound of an amplifier.” Quote from Nelson Pass*


Bingo
[/QUOTE]

I suspect most of the engineers designing those use some measurements along the way.


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## Old'sCool (May 16, 2021)

EricsAmplifiers said:


> If this does happen, I’d like to bring a ‘heater’ that will tickle yours ears. Perhaps after the amp works hard for your sonic pleasure we can then fry up an egg on it.
> 
> Perfection takes a lot of hard work is what I’m trying to say.
> 
> ...


Some of the best home amps I've been fortunate enough to own, Monarchy SE-70 (run in mono/balanced mode) and Monarchy SE-100 Deluxe monoblocks, ran so hot, I rarely listened to them in the Summer. They required at least 3 hours' warm-up to come alive. When the music started, even friends who "don't give a **** about audio" would shut thier months and listen. For hours, some nights, we'd sit in awe, as the Stones or Bob Marley played live for us.

"Love You Live," and "Neil Young: Unplugged:" never sounded so wonderful as they sounded on my sofa, with a few brews and some good company. 

Those amps and the old Grateful Dead favorite - Ampzilla, were amazing machines that defied the assumption a great Hi-Fi must cost more than a decent new car. 

I wish I'd never sold the SE-70s. I can't find another set for sale that hasn't been hiked-up by some profiteer. Sure, you could use them to dry cars in a paint booth they ran so hot, but holy smokes were they a portal into "the sound." Very rarely do I deem a system flawless; there almost always is a compromise. Slap a set of pure Class A Monarchy amps on a huge pair of planars, and the system disappears, leaving only sound.

I'm sure that sounds ludicrous to some, but to folks who've "caught the dragon..." not so crazy.


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## Holmz (Jul 12, 2017)

Old'sCool said:


> Some of the best home amps I've been fortunate enough to own, Monarchy SE-70 (run in mono/balanced mode) and Monarchy SE-100 Deluxe monoblocks, ran so hot, I rarely listened to them in the Summer. They required at least 3 hours' warm-up to come alive. When the music started, even friends who "don't give a **** about audio" would shut thier months and listen. For hours, some nights, we'd sit in awe, as the Stones or Bob Marley played live for us.
> 
> "Love You Live," and "Neil Young: Unplugged:" never sounded so wonderful as they sounded on my sofa, with a few brews and some good company.
> 
> ...


A lot of magic in ^this^... how are we supposed to believe that the amp actually took 3 hours to come alive?
A friend has some Martin Logan's and /2 dozen amplifiers including big Roland research jobs that looked like safe drawers. They sounded good with Rdk Toneff's Fairytales, and other nice music... I bought some of his hand me downs.


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## Old'sCool (May 16, 2021)

Holmz said:


> A lot of magic in ^this^... how are we supposed to believe that the amp actually took 3 hours to come alive?
> A friend has some Martin Logan's and /2 dozen amplifiers including big Roland research jobs that looked like safe drawers. They sounded good with Rdk Toneff's Fairytales, and other nice music... I bought some of his hand me downs.


Because cold, the amps did not sound good.
They were single-ended A designs.

You could track down the designer, CC Poon of Monarchy. He might 2nd that emotion.

No magic. Many audiophiles leave their "room heaters" on 24/7.


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## Old'sCool (May 16, 2021)

Holmz said:


> Bingo


"I suspect most of the engineers designing those use some measurements along the way."

Yep. And one of those is their ears.

Back to amp warm up, this is probbbbably best suited for a new thread. I'm not going to argue all day over my personal preferences/experiences. Suffice it to say, the distortion in a cold Class A amp can be quite audible from startup. Some warm up FAST...10 or so minutes, and others can take 10 or more hours (though I've never owned anything that took over 3).

Here's a link to a band of magical gypsies, debating warm-up much as folks debate AB vs D:









Is Component Warm Up Real or Imaginary?


Paul Wilson examines the concept of equipment warm up...




audiophilereview.com


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## Holmz (Jul 12, 2017)

Old'sCool said:


> "I suspect most of the engineers designing those use some measurements along the way."
> 
> Yep. And one of those is their ears.
> ...


An ear is not a measurement.
It is a final confirmation that it is all working.




Old'sCool said:


> ...
> Back to amp warm up, this is probbbbably best suited for a new thread. I'm not going to argue all day over my personal preferences/experiences. Suffice it to say, the distortion in a cold Class A amp can be quite audible from startup. Some warm up FAST...10 or so minutes, and others can take 10 or more hours (though I've never owned anything that took over 3).
> 
> Here's a link to a band of magical gypsies, debating warm-up much as folks debate AB vs D:
> ...


^It^ seems like more of an assertion than a debate?

Hitting some steady state temperature seems like it would happen relatively quickly, and the power supply will fill the capacitors pretty quickly.

In a mobile audio sense, most people are not running class-A, and most are not leaving their amps powered on... Those that do, are usually complaining that they have a dead battery.


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## Old'sCool (May 16, 2021)

The comments at bottom of the article are somewhat back and forth. It is certainly a contested topic in the audiophile world. 

Done talking about it. Let me know when you're ready to join the AB/D test.


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## MrToadsWildRide (Jun 10, 2021)

Old'sCool said:


> I never said I don't prefer a properly tuned Class D setup to a "shade tree" AB install.
> 
> Given the choice, I'll take a well done system of any type over a hack.
> 
> ...


I'm just wondering if you're reading what you're writing. Maybe I'm reading it wrong. You seem to be saying that you can hear a digitized sound in a class D amp that isn't present in a Class A or A/B amp. You can also hear the difference between a Class A amp has been warmed up for 1 hour or one that's been warmed up for 3 hours. Yet, when everything is warmed up and tuned right, your hearing isn't good enough to distinguish whether or not the banjo is actually in the room? I think psychoacoustics are at play here. I think you only "hear" these things because you're already aware of them. Maybe your hearing is remarkable, but I'm not sure if I should be impressed or feel bad for you. I'm also starting to believe that you may have an unhealthy obsession with Poon...

If Class D is so atrocious, why are companies with reputable names willing to stake their reputations on garbage?


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## Old'sCool (May 16, 2021)

MrToadsWildRide said:


> I'm just wondering if you're reading what you're writing. Maybe I'm reading it wrong. You seem to be saying that you can hear a digitized sound in a class D amp that isn't present in a Class A or A/B amp. You can also hear the difference between a Class A amp has been warmed up for 1 hour or one that's been warmed up for 3 hours. Yet, when everything is warmed up and tuned right, your hearing isn't good enough to distinguish whether or not the banjo is actually in the room? I think psychoacoustics are at play here. I think you only "hear" these things because you're already aware of them. Maybe your hearing is remarkable, but I'm not sure if I should be impressed or feel bad for you. I'm also starting to believe that you may have an unhealthy obsession with Poon...
> 
> If Class D is so atrocious, why are companies with reputable names willing to stake their reputations on garbage?


Lol @ the Poon comment.

I'm fully aware that imaging and sound stage are subjective.

I'm also fully aware how the Class A Monarchy amps sound cold vs warm.

I stated pages ago that Class D has come a long way. I own several Class D amps, but only 3 or 4 are full range.

How would I "not" hear what I know is there? Very few home systems can produce the entire image of the stand up bass in Bela Fleck's "Perpetual Motion" album. Very few. Even fewer car systems can faithfully recreate the stage. 

I do not ACTIVELY try to discount an amp when I am listening. I know it seems preposterous, but I am an audio buff because I love both music AND electronics. I listen with my ears, not my checkbook. Certainly not with any prejudice. If a Class D amp sounds excellent, I will say, "Man! This sounds excellent!" Unfortunately, even the best I've encountered are still not as clean as A/B.



A great pair of headphones easily produces the full image of the bass on "Perpetual Motion," but the stage is nestled between your shoulders, rather than where it typically resides - up front.

"The Trial" on Pink Floyd's "The Wall" disc is another great reference track. Listen to it on vinyl vs (most) CD setups, and the vinyl version has a depth to it that's absolutely staggering. On CD, you need a pretty nice DAC to get close to the same effect. With a GREAT DAC, you can pinpoint several of the "jurors" as they sing in the background.

Edit: Bela Fleck and his producers go to incredible lengths to record lifelike and realistic sound. The mics can certainly pick up every sound in the studio. Have you ever listened to the album? Have you ever heard a stand up bass live? The recording of "Perpetual Motion" is phenomenal. I urge you to listen to it on the finest home system you can find. Maybe then, you will hear the bass...right there, played before you.


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## Holmz (Jul 12, 2017)

Old'sCool said:


> ...
> How would I "not" hear what I know is there? ...
> ...


Psychoacoustics?


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## Old'sCool (May 16, 2021)

Holmz said:


> Psychoacoustics?


Have either of you ever listened to binaural recordings?

I'm literally done debating what I can and cannot hear. What you or others may hear is impossible for me to gauge, just as my hearing ability is impossible for YOU to gauge, without test tones and an in-person examination.

Here's a pretty neat recording you can search on Amazon:










You should be able to hear the doctor walk around the subject. You should also hear the subject's voice almost as if it is YOU speaking. It's kinda creepy on good cans.

An even CREEPIER recording is on "The Ultimate headphone test." (Also on Amazon.)

Search for the Binaural recording. The 1st knock will come dead-center. The 2nd knock should scare the $#it out of you with its realism and placement - several feet to your left:









If you cannot hear the knock several feet to your left, and a few feet forward, it's time to clean your ears.

The remainder of this thread will be used to discuss the AB vs D challenge. Please refrain from further thread crapping, naysaying, and general adversarial behavior.

Cheers.


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## Holmz (Jul 12, 2017)

Old'sCool said:


> Have either of you ever listened to binaural recordings?
> 
> I'm literally done debating what I can and cannot hear. What you or others may hear is impossible for me to gauge, just as my hearing ability is impossible for YOU to gauge, without test tones and an in-person examination.
> ...


Exactly.

We will have to await seeing whether the callenge shows any participants having the ability to discern the amps in a double blind setting.
Without ^that^ it is just impossible for me to gauge what you are hearing, just by reading about it in the antipodal location.

back to your magnapans... those speakers do not have a lot of X-max, and are pretty light in terms of mass. If that leads to less non linear distortion, then it seems like that may be more sensitive to the amplifier being heard.
A regular piston speaker, with 1-2% distortion, makes it unlikely that 0.01 or 0.001 % THD+N amplifiers would be showing through the already high distortion just from the speakers.

If the testing/challenge is not using some damned good drivers, then it could be hard to observe whether the amplifiers are able to be easily heard. What are the plans with the speakers?


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## Old'sCool (May 16, 2021)

A quality Tweeter, midrange and woofer will be used, per the original diagram.

The Innersound Eros MkII sound excellent via Class A Monarchy amps. They also have 10" subs in the base of each tower.

Rega Juras, Sonus Faber Concertos, and several other non-planar high end towers also sound awesome via the Monarchy amps.

The speakers selected will be of sufficient quality and detail to do the job. Why waste time using difficult to drive speakers, when we have literally any speakers we wish at our disposal.

I'll update when I have time. Getting prepped for a big job on Monday.


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## doeboy (May 2, 2012)

If you are going to take the time to go through setting all this up you should just plan to do it at an event and get people at the event to participate in the listening then fill out surveys. That would get a much larger sample size and make the large effort involved in this a lot more worth the time spent.

By event I mean one that is an industry type of event that has hundreds of people at it.


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## Old'sCool (May 16, 2021)

doeboy said:


> If you are going to take the time to go through setting all this up you should just plan to do it at an event and get people at the event to participate in the listening then fill out surveys. That would get a much larger sample size and make the large effort involved in this a lot more worth the time spent.
> 
> By event I mean one that is an industry type of event that has hundreds of people at it.


Thanks for the input!

I've considered this, and it makes sense. There are a lot of distractions and noise at a soundoff, however. This could be somewhat mitigated by having a separate room.


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## khlae (Dec 31, 2016)

Catalyx said:


> If you use top quality amps from each class and manipulate the signals to even curves I would bet big money that people won’t hear the difference.


I would love to see the results of such an experiment. To take it to the next step, it's possible to generate an impulse response and deconvolve each amp to a common target response. I've normally only corrected the entire system to a target response, but the theory isn't really any different...


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## Old'sCool (May 16, 2021)

khlae said:


> I would love to see the results of such an experiment. To take it to the next step, it's possible to generate an impulse response and deconvolve each amp to a common target response. I've normally only corrected the entire system to a target response, but the theory isn't really any different...


Or, we can just run each amp off the DM-810, and measure output with an RTA/compare.

We'd have an RTA on the input of the DSP, the output of the DSP, and sniffing the final sound.

That's a pretty dry experience, though.

Perhaps this could be used to compare what people hear vs what's "going on."


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## TrashPanda (May 21, 2021)

After reading all of this, I feel compelled to post.
I have been to Axpona, I have been around high end Audio for 30+ years. I have owned class A, Class AB and Class D in home amps.
While I agree that older (10+ years ago) designs were lacking, there are new designs being made by VERY reputable companies out there that challenge Class A and demolish AB designs. That is of course with my ears. And yes the studio walls were still there and the imaging was left right/up down/front to back.
Having Bias towards class D (read back through all of your posts and you will see this) will inevitably prevent you from hearing that.
I say this to say, a weekend event with everyone chipping in wouldn’t even come close to the data needed to properly assess the differences between a few amps. The organization and manpower would be huge.
Not to mention, all people willing to help would most likely have their own Bias which might help setup the tests to be skewed. You would truly need neutral parties setting up switching methods and products.
It is very easy to have bias and placebo in a world dominated by people’s own ears (tied to their brains) making the calls between what’s best.
Someone on here said amps should disappear, in true high end home audio, the room should. With car audio, much harder, the car should.
I digress.


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## TrashPanda (May 21, 2021)

To add, I think if the whole thing was presented as more of a fun meetup rather than organized comparisons, it would likely get more support. My op.


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## Old'sCool (May 16, 2021)

I've been reading up on the latest Class D designs.

I recall there was a time when folks said CD would never beat a Phonograph.


Don't mistake my ears' preference for bias, however; the day I hear (or rather DO NOT hear) a perfect class D, is the day I swap out all my gear.

I love old classic cars. These are typically not the best foundations for high-current sound systems, so class D makes its way into many of the systems I build. Especially for subwoofers.

I agree it's fully possible to create such a great D amp, you can no longer hear it.

Axpona does have an advantage: 120vac is easy compared to 12vdc, especially for the environmental reasons you mentioned above.

I heard some staggering systems at Axpona. I also saw $25,000 amps with iPod inputs.😰

Yes, the whole idea is to have a meet, and have fun! Isn't fun why we have hobbies.

If we start dealing with controls, triple-blind tests with a lab rat and a turtle (don't laugh - turtles are extremely sensitive to subsonics), clip boards and computerized RTAs, etc., we lose the whole idea/spirit of the rather simple challenge.

Honestly, I would've liked to have taken part in the far more detailed experiments already linked to by our resident soundoff champ. I really believe my accuracy would have surprised even the most scrutinous sceptics.

Another issue I have with too much complexity can be viewed by the results of the previous test. By the time they got around to the most important part (blind comparison) many folks had left, and there were somewhat incomplete data as a result. 

Simplicity is the best model for almost everything - be it an audio system, a building design or an experiment. 

I spent 33 pages reading f*@×ers argue over active vs passive Xovers, to the point where it escalated to major insults and hyperbole. The truth is, you can design an incredible system based around passives, as long as you understand the physics of room recreation and reflective distortion.

You can also slap a self-tuning DSP in a car and have a 98% flawless sweet spot in the driver's seat (or it can sound like DUMP active OR passive, if the speakers aren't placed properly, etc.).

The new crowd is all about tech, and for good reason. We have tuning capabilities guys like me would have traded a cajone for in the 1980s today.

Class D is making amazing strides and is 100% the wave of the future. I can admit this without losing 1mg of self worth. 

I simply state I can hear class D. Sure, maybe I can't hear it in a $12,000 home amp with single-driver speakers that cost more than my home, but in almost every car with D amps I've heard, I could tell something was off before even looking at the amp rack.


I am kicking around some more ideas, and hope to find enough folks ACTUALLY interested in this to make it fun, worthwhile, and a reality sooner than later. 

Again, I value your constructive argument and input! Thanks Panda.

-oc


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## MrToadsWildRide (Jun 10, 2021)

I didn't realize this was DIYHA, I thought it was DIYMA. It seems like 60-70% of this thread is about home audio products with a few mobile audio products sprinkled in. If the entire test is going to revolve around what car amps don't sound as good as a Monarchy Class A, I don't care. I don't see myself putting Monarchy amps in my car anytime soon. Same applies to headphones. I'm sure there are things people can hear on headphones that they can't hear in a car that's cruising at highway speed. Are there any products you'd suggest that apply to this test? JL VXi possibly? Rockford claims that the Power Series line is Class AD. Where should that fit in? Should the test be about the highest end of each class available or should it be about mid-grade products that most people are willing to use?


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## Old'sCool (May 16, 2021)

Nobody is testing home amps in this scenario.

My best car SQ build killed my best pair of headphones, and very few home systems could touch it, especially in the lower octaves.

The Monarchy Class A were _examples_.

I like the idea of trying out Rockford's "Class AD." Is it marketing? Is it amazing? Good question.

Let's add the new Rockford D stuff to potential candidates!

Thanks for the idea.


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## Old'sCool (May 16, 2021)

Okay, per Mr. Toad's suggestion, I've reviewed published vs tested specs on the Rockford T1000-4ad. This amp gets rave reviews, and seems like a worthy candidate for a showdown.

Now, who has a suggestion for an A/B 4ch amplifier with similar power output/price range?


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## Catalyx (Oct 13, 2011)

Then it would be class A/B versus class A/D so I wouldn’t use the RF


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## Old'sCool (May 16, 2021)

Catalyx said:


> Then it would be class A/B versus class A/D so I wouldn’t use the RF


There's no such thing as AD, AFAIK. It's Rockford trying to mkt to people who like AB. (I could be wrong here, but pretty sure "AD" is just clever marketing?)


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## Catalyx (Oct 13, 2011)

From what I know the input is class A and output class D on those types of amps. One could argue that narrows the comparison to only the output stage but it also opens the door for people to claim they would be able to hear a difference with a pure D model.


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## Old'sCool (May 16, 2021)

Catalyx said:


> From what I know the input is class A and output class D on those types of amps. One could argue that narrows the comparison to only the output stage but it also opens the door for people to claim they would be able to hear a difference with a pure D model.


Thanks. I'll have to read-up on them some more. I was impressed by the SN ratio and efficiency.


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## MrToadsWildRide (Jun 10, 2021)

Doesn't need to be a Rockford. Could use an Arc X2 or Hybrid Audio Unity.


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## Holmz (Jul 12, 2017)

Is the event still on?

Thought about when looking at class-D plate amps for a home theatre junior setup.

Any knowledgable HT people around?
(I need a lot of help, I have L/R, and a processor… just a 2,2 at first... And no center channel yet, so will likely start with a 2.2 and move up To a 3.2 and 5.2 Maybe 5.2.4 or 7.2.4.


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## squiers007 (Sep 12, 2012)

Holmz said:


> Is the event still on?
> 
> Thought about when looking at class-D plate amps for a home theatre junior setup.
> 
> ...


Feel free to hit me up, I'm no expert but can point you in the right direction if I don't know the answer. Also, if you haven't already jump on AVS forum.


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## TrashPanda (May 21, 2021)

Same here. Been around it for some time and have limited knowledge from multiple setups but happy to share experience 
Love HT and 2ch setups in the home.


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## 420tabbycat (Dec 23, 2013)

Well, there goes 30 minutes of my life I’ll never get back reading this. Like a movie with a bung ending…


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## fghanem (Jan 9, 2011)

420tabbycat said:


> Well, there goes 30 minutes of my life I’ll never get back reading this. Like a movie with a bung ending…


ditto


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