Do amps matter???? Kansas City blind amp comparison GTG. - AVS Forum
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post #1 of 187 Old 05-10-2013, 12:06 PM - Thread Starter
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We are going to have a GTG at my place on Saturday June 1st starting at 3:00 PM.

My initial reason for having people over was to have some local AVS friends check out my new sub setup with 8 subs with Stereo Integrity 18" drivers and my JTR Noesis 212 speakers (left, right, and center).

However, we are all very interested in experimenting with different amps when powering speakers and finding out if we can tell a difference between amps and also compare to my receiver. We can do a demo of my system too, but I figure we should wait on the amp comparison first.

We are going to do this testing blind, so it should be interesting.



So far we have various class A/B, class D, class T and class H. I am hoping that someone will have a class A amp and/or a tube amp so that we can have at least one of each type. Here is what we have:


Class A/B - Crown XLS202 (Jonathan), Emotiva XPS-3 (Jonathan)
Class H - EP4000 (Kevin)
Class D - Inuke DSP3000 (Jonathan), Pioneer Elite AVR (Sheldon)
Class T - Lepai LP-2020A+ (Jonathan)

Also, Randy Bessinger is planning on bringing some type of switching device to make it quicker to switch from amp to amp.

Anyone in the KC area that is interested in coming please PM me, I've already sent out a number of group PM's and have the following members planning on attending:

Me
Archaea
MrSmithers
Stitch1
Jedimastergrant
Scrappydue
Randy Bessinger
Robotbunny
Chirpie
Dave (non avs member but building DIY SEOS speakers)

Possibles:

ecrabb
Tesseract67
Dragoson
Beastaudio




Be aware that my hosting abilities are limited, I'm going to buy a bunch of beer but can't afford to supply food. Also... we tend to get loud at times with the volume, we won't do that until after the blind testing is over but just wanted to make that known. smile.gif
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post #2 of 187 Old 05-10-2013, 12:30 PM
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You need to make sure it's a double blind test, not just single blind, else you'll be passing nonverbal clues to each other.
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post #3 of 187 Old 05-10-2013, 12:53 PM
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Hmm, something I have that's not on the list is a Crown CE4000. It's a different topology than what's listed, but if used on mains and not subs, it has too much noise.

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post #4 of 187 Old 05-10-2013, 03:22 PM
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To make this work right with the least amount of bias, you have to have people in attendance that "claim" they have the ability to hear such differences.

Otherwise if nobody has claimed they can, then the "sample set" could be biased by people who actually cannot hear such things.

50% "can's" and 50% "cant's" would be most ideal.

The only other way to overcome this, is to have a fairly large sample set of people.
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post #5 of 187 Old 05-10-2013, 04:03 PM
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Quote:
Originally Posted by RobertR View Post

You need to make sure it's a double blind test, not just single blind, else you'll be passing nonverbal clues to each other.

Good point.

Also, fan noise revealing the item under test.

For example: the start up noise of a clone or an idling iTech is unmistakable (because you could hear it from 80ft away.)

Or the delayed relays or power-on button noise; a clear give-away.
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post #6 of 187 Old 05-10-2013, 04:29 PM
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Carp has a seperate room we can put the amps in to rule out fan noise --- in addition all of these amps listed have fan mods and are impossible to tell they are on from more than a few feet away. ground loop hum and such is potentially a different problem --- not sure how to counter that one exactly. We can have cheater plugs on hand --- I hope that's sufficient. Some amps seem to have it in his room and some don't.

Yes, we do want to test these amps on mains to test for audible difference because none of use think we can tell any difference on subwoofer usage outside of power.


For my part I know I'm farily confident I can tell a difference between the Inuke stock and the Crown XLS or Onkyo TXNR-1007. It is both measurable with a omnimic and audible to my ears. I don't think I could tell a difference between the Onkyo and Crown, and I'm unsure if I can tell a difference with the emotiva.

Carp is pretty sure he can tell a difference between the Crown and his Pioneer.

I don't know about the rest of the guys. I traditionally am from the camp that amps don't matter that much if they are reproducing the sound accurately --- and measure with the same frequency response. But I'm curious to verify if that's true, and will certaintly be critically listening to the best of my ability. The fast switching function of the box Randy Bessinger is providing will be critical for this meet's success. Listening to the amps even 5 minutes apart and trying to tell a difference will be worthless IMO.
Randy has the CS5 RM2 shown on this website
http://home.provide.net/~djcarlst/abx_hdwr.htm


I found a couple source and speaker switchers on Amazon we could purchase as alternate devices, but I don't know how good they are in comarison to what Randy has.
Obviously you don't want your switch box to color the 'sound' or output quality of the amps.

http://www.amazon.com/4-ZONE-Speaker-Selector-Switcher-Control/dp/B003ED2DZA
or
http://www.amazon.com/Selector-Switcher-Splitter-Impedance-Matching/dp/B004ZGVU7W/ref=cm_cr_pr_product_top

Any input on the offerings from amazon? Does anyone have a very high quality switcher we could borrow in addition to Randy's unit to ensure we are covered? Our group would pay shipping both ways to ensure we have backup for g2g day. We'd like to iron out the details in advance and make this testing as valid as possible.

"Without subs it's just background music - with subs it's the main event!"
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post #7 of 187 Old 05-10-2013, 06:09 PM - Thread Starter
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Quote:
Originally Posted by GIEGAR View Post

Now this should be really interesting!

Carp, you're a brave man... you realise that if you don't get the procedure spot on (or clearly state any limitations of same), when the results don't fall the way people are "comfortable" with, nit-picking the methodology after the event will likely be the focus, rather than reflecting on what the results of the day generally indicate. Nah! That wouldn't happen, would it? biggrin.gif

Think I can see where James is going with the XT -v- XT32 idea (ie. that's where the real audible difference is, right?) but it looks like another layer of complexity to me. Perhaps for another day (Part 2?).

I've got a few questions/comments on the set-up. Would you rather them here or in the other thread? Not sure of the etiquette. smile.gif




I'm not too worried about being torn to shreds. At the end of the day my main motivation for doing this is because I want to know for myself. I like discussing it here too of course, but I won't take offense if some people get upset at how we do things in fact I'm looking for input on how we should do this most effectively so - fire away with questions/comments GIEGAR. smile.gif
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post #8 of 187 Old 05-10-2013, 07:13 PM
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Very happy this is happening and looking forward to the results. I recently bought an xls202 so excited to see or not see impressions of it.
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post #9 of 187 Old 05-10-2013, 10:42 PM
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This has been brought up recently but y'all are going to need some really dynamic BDs where the author throws in some really hot signals in places. In my opinion that is where having an amp over an avr really shines and a high powered one even more since will have no trouble outputting that signal. The noes will also help show where the extra power is being used "cleanly".
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post #10 of 187 Old 05-11-2013, 04:41 AM
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Quote:
Originally Posted by Randy Bessinger View Post

this has to be done right. Curtis Chang can we borrow Shawn's QSC switch? I will vouch for returning it. To the extent you are not friends with Shawn can you ask Sanjay? Arny, I have one of the originals... Can u help?

I concur with this 100%.

If people cannot reliably discern through an ABX I have no interest in the results of an "a sounds better than b" trial. No offense to anyone here, it simply does not interest me.

If we're really after the truth a properly executed abx will unearth it.

Good luck!

James

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post #11 of 187 Old 05-11-2013, 05:41 AM
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Quote:
Originally Posted by carp View Post

I'm not too worried about being torn to shreds. At the end of the day my main motivation for doing this is because I want to know for myself. I like discussing it here too of course, but I won't take offense if some people get upset at how we do things in fact I'm looking for input on how we should do this most effectively so - fire away with questions/comments GIEGAR. smile.gif

Yeah, you really shouldn't get torn to shreds because I know you fellas will have a red hot go at planning and doing it with the aim of learning and having fun and beer! smile.gif

The big thing you have in your favour is those ripper JTR Noesis'... by all accounts accurate, clear, very loud and dynamic (zero compression). I reckon their qualities effectively take speaker behaviour out of the mix to allow the group to concentrate on the amps.

I'm by no means an expert at this, but have a few questions that I've seen thrown up previously:

  • The comparison is meant to be conducted below clipping. How will the group ensure/demonstrate that all amps will never clip on any of the material? Is the only way to do this with an oscilloscope?**
  • On the current lineup, I guess the little T-amp will be the limiting factor? The level would have to be selected so it never clips and then the rest of the amps level matched to it right? Which leads me on to...
  • How will the group ensure all amps are level matched? Not sure what the accepted tolerance is for level matching, but I think it's in the order of fractions of a decibel (+/- 0.2dB?).
  • What will be compared to what? Do you intend to set up a matrix whereby every amp will be compared to the AVR only and then all amps compared to each other?

That's about all I can think of at the moment. Good luck and have fun with the planning! smile.gif

**PS: Actually, what would be really intriguing would be if there was a little bit of occasional light clipping going on and the group still couldn't pick the difference. biggrin.gif
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post #12 of 187 Old 05-11-2013, 07:25 AM - Thread Starter
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Quote:
Originally Posted by GIEGAR View Post

Yeah, you really shouldn't get torn to shreds because I know you fellas will have a red hot go at planning and doing it with the aim of learning and having fun and beer! smile.gif

The big thing you have in your favour is those ripper JTR Noesis'... by all accounts accurate, clear, very loud and dynamic (zero compression). I reckon their qualities effectively take speaker behaviour out of the mix to allow the group to concentrate on the amps.

I'm by no means an expert at this, but have a few questions that I've seen thrown up previously:

  • The comparison is meant to be conducted below clipping. How will the group ensure/demonstrate that all amps will never clip on any of the material? Is the only way to do this with an oscilloscope?**
  • On the current lineup, I guess the little T-amp will be the limiting factor? The level would have to be selected so it never clips and then the rest of the amps level matched to it right? Which leads me on to...
  • How will the group ensure all amps are level matched? Not sure what the accepted tolerance is for level matching, but I think it's in the order of fractions of a decibel (+/- 0.2dB?).
  • What will be compared to what? Do you intend to set up a matrix whereby every amp will be compared to the AVR only and then all amps compared to each other?

That's about all I can think of at the moment. Good luck and have fun with the planning! smile.gif

**PS: Actually, what would be really intriguing would be if there was a little bit of occasional light clipping going on and the group still couldn't pick the difference. biggrin.gif


I don't know the answer to your questions, but I'm sure someone that knows will. I honestly don't know yet how everything will be setup.

I do think we should test 2 different ways. I think we should do a test attempting to not have any clipping and then later compare again with the volume cranked up a bit to see how much of a difference that makes. A big motivation for me to try this blind test is to see if I need to buy an amp, and I like it loud at times for music and movies so not testing it that way makes no sense for me.

Also (Archaea brought this up and I agree) I think we need to get a hold of some low sensitivity fuller range towers to use as well. My speakers are 101 db sensitivity rated to 60 hz so that may not tell us much of we can't distinguish between an amp(s) and receiver especially on the non-clipping test.

I didn't know the level matching had to be that close, but we can give it our best shot using my omnimic db meter and calibration disk test tones (I have Avia and Disney's WOW disks).
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post #13 of 187 Old 05-11-2013, 07:40 AM
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I've a/b many mid and highend amps over the years, and yes there is or can-be a different sound between amps, more so with driving different loads (speakers). One load may not easly prove to show the differenences between amps while another load would make it easy for everyone to hear it. Also when listening to your favorite tracks, the better amp may only shine above the others for just a few notes, so you really need to listen.. Of couse if someone can't hear it, than to them the amps do sound the same..
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post #14 of 187 Old 05-11-2013, 07:44 AM
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This test sounds really cool! I am looking forward to the results. Good luck with the tests!
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post #15 of 187 Old 05-11-2013, 07:50 AM
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Quote:
Originally Posted by joehonest View Post

I've a/b many mid and highend amps over the years, and yes there is or can-be a different sound between amps, more so with driving different loads (speakers). One load may not easly prove to show the differenences between amps while another load would make it easy for everyone to hear it. Also when listening to your favorite tracks, the better amp may only shine above the others for just a few notes, so you really need to listen.. Of couse if someone can't hear it, than to them the amps do sound the same..

Please provide a list of speakers that would allow people to hear a difference so the team can try and accomdate.

 

This to me sounds like someone who can't pass a double blind test but still insists they hear differences.  biggrin.gif

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post #16 of 187 Old 05-11-2013, 08:10 AM
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Please provide a list of speakers that would allow people to hear a difference so the team can try and accomdate.

This to me sounds like someone who can't pass a double blind test but still insists they hear differences.  biggrin.gif
I have a pair of magnepan tympani 1d speakers that I only use for stereo music playback. Over the years I have used amps from mac (tube), many A/B class amps, to many to list and now a crown xls1000 class D.
The class D to my ears has a sweet highend, this is without any EQ.. Speakers over the years were AR 3a and JBL L100. I've owned and listened to many other speakers, but these were my favorites over the years

I can say forsure the crown xls 1000 is the best amp for the money that I've owned. I would to buy a crown xls 2500, if Ididn't have the 1000..
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post #17 of 187 Old 05-11-2013, 08:30 AM
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Quote:
Originally Posted by GIEGAR View Post


**PS: Actually, what would be really intriguing would be if there was a little bit of occasional light clipping going on and the group still couldn't pick the difference. biggrin.gif
100db/w speakers being fed 6-700w with one of those Beri amps. After that, I would be intrigued if anyone could accurately discern anything over the ringing in their ears. 130db is loud

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post #18 of 187 Old 05-11-2013, 12:45 PM
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Here is a post by Tom Danley on amps that you all might find interesting: http://www.avsforum.com/t/1189404/danley-dts-10-super-spud-diy-kit/210#post_17409024

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post #19 of 187 Old 05-11-2013, 05:06 PM
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Originally Posted by Looneybomber View Post

Quote:
Originally Posted by GIEGAR View Post


**PS: Actually, what would be really intriguing would be if there was a little bit of occasional light clipping going on and the group still couldn't pick the difference. biggrin.gif
100db/w speakers being fed 6-700w with one of those Beri amps. After that, I would be intrigued if anyone could accurately discern anything over the ringing in their ears. 130db is loud

So would I, and yes it is. But I wasn't talking about, or suggesting running all amps into clipping. I thought it was pretty self evident that in a level matched scenario it would be lower powered units (T-amp, AVR etc) that might clip occasionally on peaks, while the big boys sail on by with plenty in reserve.
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post #20 of 187 Old 05-11-2013, 05:28 PM
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Quote:
Originally Posted by AV Science Sales 5 View Post

Here is a post by Tom Danley on amps that you all might find interesting: http://www.avsforum.com/t/1189404/danley-dts-10-super-spud-diy-kit/210#post_17409024

Thanks for the link Mike, that's a great reference post. One to bookmark.

From that post (bold mine):
Quote:
The amplifiers did not all sound the same, after searching recordings I found a couple parts where one could reliably hear differences, not in anything obvious BUT oddly in the decay parts of the sounds.

Anyway at a modest level (peaks about -15 -20dB on the Thresholds fast meter, it began to be different in a different way, it sounded slightly less dynamic.
I was very puzzled (it was my listening amp at home) and grabbed an oscilloscope and examined the outputs. Sure enough around the point it began to sound less dynamic, it had reached instantaneous clipping.

TO BE CLEAR this is nothing like clipping which everyone knows, this was ONLY detectable if one had a without version to compare to (in this case from a much larger amplifer).
By it self, it sounded fine, no problems and that not hearing the problem is exactly why most sound level meters and other volume level indicators do not show the peak requirements.

Anyway, my point (looking at the clock) it that to preserve or realistically reproduce sounds, you often need a far larger peak level than you would ever guess based on the ubiquitous Sound level meter. Of course all of this is irrelevant if your producing near steady tones, I am talking about dynamics.
You simply can't produce short large peaks unless the system can produce them at all in the first place. Headroom is your friend.

The bold bit describes what I was trying to say above. I think you got it. smile.gif
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post #21 of 187 Old 05-13-2013, 07:21 AM - Thread Starter
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Updated first post, 10 people confirmed with 4 possibles.
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post #22 of 187 Old 05-13-2013, 07:42 AM
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Mind if I add a couple of points. I did a comparison between an Emotiva XPA-5, Marantz MM8077 and the Parasound A-51. I used 3 different speakers with a pair of $800 cables.
Marantz 8801 Pre, FLAC files
Dali speakers
Ikon 7 $3295, Mentor 2 $2800, Helicon 300 MK2. $4000
All 3 amps with the Ikons and Mentors. No difference between the amps.
When I added the Helicons, you "could" hear minimal difference between the XPA-5 and the MM8077. When the Parasound was switched in it was significant. Imaging, dynamics etc. The speaker came to life.

So make sure you have a speaker that is able to pull the differences out of an amp.

Life is enjoyable with good quality
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post #23 of 187 Old 05-13-2013, 07:51 AM
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Carp - I'm glad this is going down. A few thoughts:

Are you going to use a standardized volume? If so, what will it be? I can tell you if there are going to be differences it will be much more noticeable at higher volumes.

Are you planning to use any higher power amps like the CV5000 or Jonathan's XLS5000? I would for sure include something like one of those to see if all the added power will amount to much, audibly.

I recently picked up a Crown XLS2000 and I agree it's an awesome amp. Noise floor is super low (comparable to my Denon receiver) and allows for some serious cranking with no distortion. I can't say for sure if it's contributing to much under reference - I suppose I will also have to do a test to find out.
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post #24 of 187 Old 05-13-2013, 08:02 AM - Thread Starter
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Quote:
Originally Posted by Gorilla83 View Post

Carp - I'm glad this is going down. A few thoughts:

Are you going to use a standardized volume? If so, what will it be? I can tell you if there are going to be differences it will be much more noticeable at higher volumes.

Are you planning to use any higher power amps like the CV5000 or Jonathan's XLS5000? I would for sure include something like one of those to see if all the added power will amount to much, audibly.

I recently picked up a Crown XLS2000 and I agree it's an awesome amp. Noise floor is super low (comparable to my Denon receiver) and allows for some serious cranking with no distortion. I can't say for sure if it's contributing to much under reference - I suppose I will also have to do a test to find out.


I want to test it 2 different ways, one with lower volume (10-15 under reference? not sure, I'll talk to the other guys about that) and another at louder volumes. I want to see if there is any difference when none of the amps are clipping (not sure how to determine that....) but I also want to know if I need to buy an amp so for that I want to test at higher volumes as well.

Also, if it becomes apparent that amps make a difference at lower volume levels on the Noesis then case closed, but I think we need to have a lower sensitivity speaker as well to test this out.

I'm going to leave my cv5000 on the subs, so I'll ask Jonathan if he can bring his xls5000.

Very cool to hear that the xls2000 has a low noise floor, the crown xls 202 that I'm using now does not I'm getting quite a bit of hiss. Yesterday I did turn up the receiver pre amp volume so I could turn down the amp gain, but the hiss is still there. I can't hear it from the LP but I can from about 4 feet away from the speakers.
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post #25 of 187 Old 05-13-2013, 08:32 AM
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Originally Posted by GIEGAR View Post

[*] How will the group ensure all amps are level matched? Not sure what the accepted tolerance is for level matching, but I think it's in the order of fractions of a decibel (+/- 0.2dB?).
I'm not sure if this is how they will do it, but amps are level matched by measuring the output voltage of the amplifier at the speaker terminals. You determine with one amp what listening level you want, then you disconnect the speakers and measure the output voltage while playing a sine wave. Use the same output voltage on all other amps/receivers and you will be exactly matched.
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post #26 of 187 Old 05-13-2013, 08:56 AM
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For me it would be hard to tell differences between high quality amps in any other listening environment than my own. My room is tailored to me so I know it well but someone else's HT room would be difficult , very difficult. To many other factors play into it so I would not know if the differences in sound was the amps , the room, or just unfamiliar equipment It would be a guess at best.
If it is high quality amp vs AVR at reference level (or above) with demanding source material I believe I could tell the difference. If it was my room I know I could.wink.gif
Hopefully you can score a high wattage high quality HT amp. smile.gif
I am definitely interested in this discussion.
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post #27 of 187 Old 05-13-2013, 06:37 PM
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Quote:
Originally Posted by desertdome View Post

Quote:
Originally Posted by GIEGAR View Post

[*] How will the group ensure all amps are level matched? Not sure what the accepted tolerance is for level matching, but I think it's in the order of fractions of a decibel (+/- 0.2dB?).
I'm not sure if this is how they will do it, but amps are level matched by measuring the output voltage of the amplifier at the speaker terminals. You determine with one amp what listening level you want, then you disconnect the speakers and measure the output voltage while playing a sine wave. Use the same output voltage on all other amps/receivers and you will be exactly matched.

Thanks for that.
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post #28 of 187 Old 05-13-2013, 07:19 PM
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http://www.jamo.com/speaker-lines/accessories/connectors//?sku=JSS6-HP

I emailed jamo and asked if this unit could be wired up in reverse. Six amps on two sets of speakers, instead of two sources on six pairs of speakers.

I really think quick a/b switching switching capability will be more useful/revealing than swapping out between sessions.

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post #29 of 187 Old 05-13-2013, 08:20 PM
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Quote:
Originally Posted by Archaea View Post

http://www.jamo.com/speaker-lines/accessories/connectors//?sku=JSS6-HP

I emailed jamo and asked if this unit could be wired up in reverse. Six amps on two sets of speakers, instead of two sources on six pairs of speakers.

I really think quick a/b switching switching capability will be more useful/revealing than swapping out between sessions.

Quick switching will be a must as talked about earlier. I've never tried using zones on avrs with amps hooked up to them. Is that even an option?
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post #30 of 187 Old 05-13-2013, 10:41 PM
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Originally Posted by Dr_Mark View Post

Mind if I add a couple of points. I did a comparison between an Emotiva XPA-5, Marantz MM8077 and the Parasound A-51. I used 3 different speakers with a pair of $800 cables.
Marantz 8801 Pre, FLAC files
Dali speakers
Ikon 7 $3295, Mentor 2 $2800, Helicon 300 MK2. $4000
All 3 amps with the Ikons and Mentors. No difference between the amps.
When I added the Helicons, you "could" hear minimal difference between the XPA-5 and the MM8077. When the Parasound was switched in it was significant. Imaging, dynamics etc. The speaker came to life.

So make sure you have a speaker that is able to pull the differences out of an amp.

This is an interesting anecdote; however, you obviously have a bias for more expensive gear. The dollar figures in your point are irrelevant unless you have an obvious bias that they are relevant.

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