Do amps matter???? Kansas City blind amp comparison GTG. - Page 2 - AVS Forum | Home Theater Discussions And Reviews
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post #31 of 186 Old 05-14-2013, 08:41 AM
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Yeah sorry, I should have just ignored the post. My comment didn't add anything to the discussion.

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post #32 of 186 Old 05-14-2013, 02:20 PM
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Originally Posted by SXRDork View Post

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.

So going into an amp challenge with a clear 100% knowledge that no one will hear anything is your response. I point out that speakers were a factor in hearing anything between 3 different amps and you pick on the money I spent. What I was trying to point out was it took a very good and unfortunately expensive speaker to hear any difference between amps.

If you believe an Emotiva XPA-5 amp is too expensive for your tastes that is also acceptable.

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post #33 of 186 Old 05-14-2013, 03:47 PM - Thread Starter
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Yeah sorry, I should have just ignored the post. My comment didn't add anything to the discussion.

If I stuck by that rule I would never post. smile.gif
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post #34 of 186 Old 05-16-2013, 12:59 PM
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Hey carp, I see Jonathan is bringing his 3000dsp. I've got a1000dsp I could bring as well.

Man, I wish I was further along on another project of mine, I'd have a couple of class-A tube amps to try.

-Nate
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post #35 of 186 Old 05-16-2013, 04:37 PM - Thread Starter
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Originally Posted by robotbunny View Post

Hey carp, I see Jonathan is bringing his 3000dsp. I've got a1000dsp I could bring as well.

Man, I wish I was further along on another project of mine, I'd have a couple of class-A tube amps to try.

-Nate

Yeah, I have the inuke 3000 now haven't tried it yet, I currently am using his Crown xls 202.

Aww man that's too bad, I really want to get a class A amp. I hope we can get one here somehow.
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post #36 of 186 Old 05-17-2013, 10:03 PM
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It's a bit ridiculous how much time I've spent trying to research this online and find a product we could use -- but everything is leading to dead ends. However, I think I've figured out a way to quickly switch amps for A/B/C/D amplifier comparison in a manner that cannot affect sound quality. I'd like to get additional input from the forum here to ensure this idea is solid.

I've contacted a lot of companies and people in search for a store bought solution - including Jamo, Klipsch, Part's Express, my work Facilities, avsforum friends and a couple engineers I know and nobody really had any direction on how we could set this up to do fast switching with multiple amps. All of the store bought solutions I've come across only let you switch a pair of amps - and not 4 or 6 amps like we would like to do. I spent about 3 hours at home depot tonight looking at all their hardware trying to figure out a way to make a custom and safe switch board. When I thought I had something that worked I called a couple friends to confirm what they thought. I think MrSmither's and I independently came up with the same solution and tonight when I asked him if he thought it would work he was of the opinion it was the only thing that he could think of that might work as well.

So here it goes.

GOALS for G2G!
  • Fast amp switching with no setup delays - no time for placebo, emotion, frustration, tiredness, gas pain, or boredom to affect results
  • Everybody gets a turn to sit in the sweet spot with their favorite songs and man the switch box to quickly switch through the amp types and hear for themselves if there is a worthwhile difference
  • Find/use a switching mechanism that does NOT affect sound quality!
  • Utilize the KISS principle - (keep it simple stupid) - no advanced software, hardware, trickery, no stuff to mess up. Let's try to use a physical switching mechanism.



HOW CAN WE DO THIS?
  • All amps are will be powered on at all time and will be level matched before the meet.
  • The same two speakers will be demoed on each amp in stereo. If interest holds we can swap the speakers out for low sensitivity full range speakers at some point and repeat.
  • Each amplifier will be switched at the speaker output side using two double pole single switches. One for the left channel and one for the right channel. Double Pole Single Throw Switches toggle connection with both wires that pass through them - not just a single wire like most typical wall switches.


Here is my kitchen floor mockup


That was pretty crappy and doesn't depict the wiring very well - so here's a visio'esqe diagram. tongue.gif

Notice the switches are organized into pairs. Each pair will control the left and right speaker for one amp. You flip up the left switch and you'll get the left speaker, you flip up the right switch in the pair and you'll get the right speaker. Typically you'd turn on or off each amps switches as a pair (designated by different colored face plates) Turn them both off and then flip the next amp's pair on and you are now auditioning the next amp. Amps can be swapped as fast as you can toggle pairs of switches. A/B/C/D - easy as pie to cycle through. BUT -- turn on two amp's pairs of switches at once by accident - and somethings gonna fry... frown.gif So caution and deliberate switch management is critical.


Here are the Double Pole Single Throw switches I picked up at Home Depot. They cost about $6 each x 8. 1/2" Mounting board was $3. 2 gang boxes were $2.25 x 4. Face plates were $1.25 x 4




So -- What challenges does this scenario face?
  • If two amp switches, IE amp A and amp B switches are both turned on at the same time we are going to fry something or at least throw a amp breaker - NOT COOL! eek.gif Obviously everything should be off and then each amp flipped on one at time to prevent to amps from loading the same line. Since we aren't powering down the amps - the switches can be flipped as fast as the auditioner wants - just only one switched pair of channels turned on at a time. Hence the reason I got four different colored face plates. If someone wanted to be careful they could engage the left channel of amp A and the right channel of amp B for instance in this setup -- but you'd have to be especially cautious you didn't engage two left channels on accident, and in a group setting it would probably be wise to just engage one amp in full at a time to avoid confusion, mistakes, and heartache.
  • We need gads of identical speaker wire - we need to run eight speaker wire pairs from the four amps to the main listening position couch to the switch console. Then those outputs after the switches combined and run a single wire to L speaker and a single wire to R speaker.
  • We will be splitting the output signal from the AVR three times using Y splitter -- are we going to lower the output voltage too much from the AVR L/R output for the amps incoming signal? Will we have unwanted amp noise from splitting the signal three times?



I'd like some input and suggestions before I proceed with building this switch box. I bought all the parts already - except the speaker wire - but the parts can be taken back, if this isn't going to work - or someone has a better suggestion. The Roger Russel wire table says we can use 14 gauge wire for up to 40 foot runs to 4ohm and up to 80 foot runs at 8ohm without signal degradation (http://www.roger-russell.com/wire/wire.htm#wiretable). 40 foot runs should cover the distance from the amp to the couch switch box (20ft) and then from the couch switch box to the front speakers (15foot) in carps room. So really we need to buy about 200 feet of speaker wire to make these ten 20 foot runs happen. But once I start cutting on 200 foot of speaker wire then I can't return it -- so I'm going to commit to this before I proceed much further.

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post #37 of 186 Old 05-17-2013, 10:40 PM
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We could do some sort of bracket type winner - based on popular blind vote. Something like this - but replace the real amp names with Amp A, Amp B, Amp C - etc.
Everyone would rank the four initial amps with a place of 1-4. Total sum of these votes from the group determines a winner that moves forward.

It'll be cool to see if a recognizable trend on the winners is chosen.


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post #38 of 186 Old 05-17-2013, 11:36 PM
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Looks like this speaker wire might be the way to go
http://www.amazon.com/12ga-Caliber-Xtreme-Speaker-Installatiolation/dp/B005F5NSRC/ref=sr_1_23?s=electronics&ie=UTF8&qid=1368855306&sr=1-23&keywords=speaker+wire

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post #39 of 186 Old 05-17-2013, 11:38 PM
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i do not think this would be a good solution.

the primary problem is simply one of credibility. "well of course those dopes couldn't hear a difference, they were running the signal through light switches. that is going to mask all the detail of the amplifier..."

the second is that each light switch may impact the signal differently in some way, so you may actually be hearing differences in the switches, not the amps.

as much of a pain in the butt that it will be, i'd suggest an "habx" method as used here: http://www.matrixhifi.com/contenedor_ppec_eng.htm

also, it will be VERY important to get the frequency and level set as close as possible. even a 0.2db difference in level could swing the results.

Listen. It's All Good.
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post #40 of 186 Old 05-17-2013, 11:56 PM
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Thanks for the post LTD02. I appreciate and value your opinion. I agree that level matching will be critical - someone suggested using a multimeter to measure voltage out on each of the speaker lines with a steady tone and that tactic might be more accurate than using an SPL meter on the Speaker's tone. (or a least a combination of the two methods perhaps to help ensure accuracy).

As to the switches not being 'audiophile' approved...
Tests with expensive speaker wire vs. tin lamp cord vs. coat hangers as speaker wires have revealed 0 difference right in blind testing so long as the wire gauge is sufficient? The switches I picked up are simple on/off switches -- They should not modify the signal in anyway - just pass or cut signal. I could test them all with a multimeter to verify there are not any resistance differences in them in any manner. What else would you suggest testing? Do you doubt the capability of switch to transmit the voltage as easily as speaker wire? On what basis? Again I'm not an engineer - just trying to determine a practical way to quickly test these amps and learn a bit in the process.

The article you linked is fantastic and I've seen it before - but as you mentioned that procedure is a bear to setup and would be nigh impossible to compare six or eight amps in short order. The beauty of a switchbox system is everybody is in the midst of it, and can interact with the switchbox directly on their turn in the sweet spot. Each person can swap amps as often as they want during their favorite song demos and verify for themselves if it makes any difference. Nobody else need be involved during that individuals demo session. They are in full control for a few minutes - then the next person gets the switch box --- rinse - repeat - compile results.

As to being a bunch of dopes --- I've been called worse --- and recently. tongue.gif

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post #41 of 186 Old 05-18-2013, 12:11 AM
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i don't think the light switches would make much of a difference... just pointing out some of the noise that you are likely to hear after the test.

Listen. It's All Good.
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post #42 of 186 Old 05-18-2013, 04:47 AM
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Jonathan - what about using a rotary switch in lieu of multiple single switches? This way you could guarantee only one amp would be connected at a time. You would want a double pole (or maybe even 4 pole) 4+ position switch. I will hope an engineer chimes in with an acceptable voltage and current rating. tongue.gif I will as my buddy today as well. Grainier, mouser, and maybe even amazon should have many options for this.
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post #43 of 186 Old 05-18-2013, 04:52 AM
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Oh - and as for a switch possibly impacting the sound why not do some tests beforehand with switch/ no switch in the mix? Blind comparison with the same amp, voltage readings as the speaker, and FR charts. A bit of work? Yes it is, but can guarantee the signal is still pure for the doubters. biggrin.gif
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post #44 of 186 Old 05-18-2013, 07:10 AM
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Rotary or slide switch with four or more positions and double or quad throw sounds great but I looked for hours and couldnt find one rated with enough amperage to be comfortable. Probably a problem with me not knowing the tech that well or the terminology to know where to look and the proper search terms. Suggestions on which rotary or slider switch are certainly welcome.


http://www.digikey.com/product-search/en

^ is a fantastic fantastic site with thousands of switch options and yet I failed to find anything that would work. Ideas or recommendations?


Good call on blind testing the switches first. Thanks for the input!

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post #45 of 186 Old 05-18-2013, 07:16 AM - Thread Starter
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I love the idea of switching on the fly like this, I sure hope it works out. I also REALLY hope we can get our hands on a tube amp and a class A amp. Jonathan, thanks so much for taking to time to figure something like this out, if left up to me we would have been switching the old fashioned way which takes forever and by that time audio memory is kaput.

Assuming the switching idea works fine and we go through the initial blind testing with all amps level matched and so that the volume is equal for all (and probably doing the same thing with lower sensitivity full range speakers), I'd like to do a second type of comparison where each listener can adjust the volume up and down (in my case going quite high with the volume for very short moments). This way we can see how much of a difference there is when the amps are pushed and if it's easy to hear the difference between an amp and a receiver at higher volumes.
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post #46 of 186 Old 05-18-2013, 07:18 AM - Thread Starter
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Quote:
Originally Posted by robotbunny View Post

Hey carp, I see Jonathan is bringing his 3000dsp. I've got a1000dsp I could bring as well.

Man, I wish I was further along on another project of mine, I'd have a couple of class-A tube amps to try.

-Nate

Nate, so you are saying you will be buying new amps sometime soon? Why not get them now, that way if it ends up you don't prefer them at the GTG you could send them back - of course I give that advice with a completely selfish motive. wink.gifbiggrin.gif
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post #47 of 186 Old 05-19-2013, 12:59 AM
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Quote:
Originally Posted by Archaea View Post

We could do some sort of bracket type winner - based on popular blind vote. Something like this - but replace the real amp names with Amp A, Amp B, Amp C - etc.
Everyone would rank the four initial amps with a place of 1-4. Total sum of these votes from the group determines a winner that moves forward.

It'll be cool to see if a recognizable trend on the winners is chosen.

The objective shouldn't be to find "preferences" or "winners". That would be meaningless unless a given listener has proven to a level of statistical significance that he can tell one amp from another. Just because a user claims he prefers, say, Amp A (Emotiva) over Amp B (Pioneer AVR) doesn't count for anything; anyone could do that. I could make that claim right now from halfway across the country, and I don't have access to either amp.

The valid approach would be "ABX." Can they match Amp A or Amp B to Amp X (which repeats either A or B)? Either they can or they can't. If they can, sure, then I suppose they could state a preference, but that would be secondary. If their "ABX" identification comes up random, then anything else they claim would be useless data.
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post #48 of 186 Old 05-19-2013, 07:48 AM
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Originally Posted by Brownstone322 View Post

The objective shouldn't be to find "preferences" or "winners". That would be meaningless unless a given listener has proven to a level of statistical significance that he can tell one amp from another. Just because a user claims he prefers, say, Amp A (Emotiva) over Amp B (Pioneer AVR) doesn't count for anything; anyone could do that. I could make that claim right now from halfway across the country, and I don't have access to either amp.

The valid approach would be "ABX." Can they match Amp A or Amp B to Amp X (which repeats either A or B)? Either they can or they can't. If they can, sure, then I suppose they could state a preference, but that would be secondary. If their "ABX" identification comes up random, then anything else they claim would be useless data.

I think the problem is that they want to test several different types of amps and ABX implies just two amps. With 6 amps you would have many many trials that would not be doable in a one evening/afternoon session. Other than that, I agree with you that you need to be able to identify beyond a statistical "just guessing" number of trials to be valid as a double blind or blind test.
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post #49 of 186 Old 05-19-2013, 09:22 AM
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Have you guys explored any products from audio authority? They make some high end switching gear - some of which can be found on eBay. This looked interesting, although I'm not sure what else you would need:

http://www.ebay.com/itm/300902398711

http://www.ebay.com/itm/300902398742

http://www.ebay.com/itm/271190231053
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post #50 of 186 Old 05-19-2013, 09:49 AM
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Originally Posted by Randy Bessinger View Post

I think the problem is that they want to test several different types of amps and ABX implies just two amps. With 6 amps you would have many many trials that would not be doable in a one evening/afternoon session. Other than that, I agree with you that you need to be able to identify beyond a statistical "just guessing" number of trials to be valid as a double blind or blind test.

I get that point. I do. I can appreciate the logistical challenges. But having users declare "winners" without first demonstrating that they can actually hear differences is of no value. It's important to approach the experiment in that context.

Have you ever seen that "study" that sometimes gets linked on these forums where users, in blind testing, chose their preferences between what turned out to be a "premium" system and a shoddy one? As I recall the results, about 1/3 preferred the "nice" system, about 1/3 preferred the "not so nice" system, and the remaining third admitted they couldn't tell the difference. Although the results didn't speak well for exotic cables or stands or the like, I've seen people here insist (vehemently) that this was "proof" that 2/3 of the listeners -- their preferences notwithstanding -- could in fact hear differences between the systems. (People really think this way, apparently.)

See the flaw in that logic? The "preferences" were probably random, and in fact the data distribution suggested random guessing. We certainly had no data to tell us otherwise or, for that matter, any indication that the listeners were actually paying attention or weren't flipping coins or were even there at all.

I think we'd be better off with four amps, which could be compared with six head-to-head trials (A-B, A-C, A-D, B-C, B-D, C-D). To make it interesting, I'd pick four solid-state amps that were similar, yet different: Maybe an AVR in two-channel mode, then a value-priced power amp (like an Emotiva), then a premium-priced amp (like a Krell or Bryston or McIntosh), then a Class D amp (maybe a Rotel). I agree that it'd be cool to include professional amps and tubes and Class A, but I'd start with solid-state consumer amps and see what happens there first. Later rounds could branch into pro amps and alternate topologies.

Just my two cents.
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post #51 of 186 Old 05-19-2013, 11:43 AM - Thread Starter
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Originally Posted by Brownstone322 View Post

I get that point. I do. I can appreciate the logistical challenges. But having users declare "winners" without first demonstrating that they can actually hear differences is of no value. It's important to approach the experiment in that context.

I agree with this - Jonathan your thoughts?
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post #52 of 186 Old 05-19-2013, 02:04 PM
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I don't really care one way or the other but I don't understand the rub either.

Each person does their own tally sheet while they sit in the hot seat. Nobody is influencing any voting - each person votes with their own ears on their particular favorite songs. The brackets are blind and the user has no idea which of the four amps is which during their switching. All score sheets are summed. Winner is chosen by popular vote. If the scores are all over the place then you are right, there is no clear winner. I know most of the guys attending and have hung out with them a lot. Most of us will call a spade a spade without concern and nobody has any vested interest in these different amps. If we don't hear a difference we'll all say so. If we do - and the difference is clearly superior - voting should trend that way. Heck, it might be we give up our little excersise after the first round because it all sounds the same to everyone and we choose instead to listen to carp's eight eighteen inch subs cut loose. smile.gif

To me this sure sounds like a lot more fun than dutifully listening to the same songs over and over again and waiting for setup changes, not being in the sweet spot, etc etc. Here everybody can sit in the sweet spot for a few minutes - pick their own music - hot swap amps as often as they want and vote on their favorite - or just voice that they all sound identical. Sounds simple, easy, and fun.

This wont' be a definitive bullet proof scenario - but it'll be fun and we are making sure we make it as fair as possible by using identical speaker wire for all the amps etc.

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post #53 of 186 Old 05-19-2013, 03:47 PM
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Well I just finished checking the Home Depot Double Pole Single Throw switches with a multimeter. They'll work just fine IMO.

The way I tested was I downloaded NCH Tone Generator and played back a series of 10 tones over my system with my multimeter plugged into the speaker wire output of the Emotiva XPA3 at reference level. Then I connected a bit of speaker wire to the DPST switch and connected the multimeter to the other pair of terminals on the switch and repeated the tones. I measured ACV in each instance and here were the results. (as a side note it is interesting that it does not appear my system (signal source? HPTC's soundcard? software? AVR? Emotiva? whatever) is flat through the audible frequency range I tested. Just for fun I'm going to retry this test on the Onkyo AVR alone and see if the ACV number variances are the same.)



Only one measurement was different at 12,800hz and it was jumping back and forth slowly so it was probably just a threshold/rounding issue on the multimeter more than an actual issue to be concerned about. Keep in mind these measurements were captured at actual reference levels - so I think that proves the switches are good for the task at hand as they don't affect the numbers regardless of frequency.


Anyone see anything I missed?

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post #54 of 186 Old 05-19-2013, 04:26 PM
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Compared Onkyo to Emotiva. Seem very similar - so my top end rolloff must be somewhere in my signal chain - I do not have Audyssey or other EQ engaged. Oh well -


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post #55 of 186 Old 05-19-2013, 08:32 PM
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The switches seem like a good way to go. If you wanted something even faster you could play with some automotive-style 30A relays (it will cost you more though). Same basic idea as what you are doing, just you are using some low voltage to swing things. With relays you really could switch between things in less than a second as you essentially have a small electric motor actually switching between one wire and another.
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post #56 of 186 Old 05-19-2013, 09:25 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.

Michael in your experience do amps scale in parallel as the volume increases? So say we level match everything to 85 dBfor the initial run through. If later we turn up the volume 5 or 10dB on the AVR will all these amps still be rising in nearly perfect unison until their maxes are reached?

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post #57 of 186 Old 05-22-2013, 12:47 PM
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Quote:
Originally Posted by urapnes1 View Post

The switches seem like a good way to go. If you wanted something even faster you could play with some automotive-style 30A relays (it will cost you more though). Same basic idea as what you are doing, just you are using some low voltage to swing things. With relays you really could switch between things in less than a second as you essentially have a small electric motor actually switching between one wire and another.

I'm all ears, but I'm unfamiliar with what you are talking about. Do you have a link or a product to specifically recommend? How would we control the switches electrically?

Quote:
Originally Posted by Gorilla83 View Post

Have you guys explored any products from audio authority? They make some high end switching gear - some of which can be found on eBay. This looked interesting, although I'm not sure what else you would need:

http://www.ebay.com/itm/300902398711

http://www.ebay.com/itm/300902398742

http://www.ebay.com/itm/271190231053

I'm going to e-mail the seller and see if http://www.ebay.com/itm/300902398711 would work as a standalone?

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post #58 of 186 Old 05-22-2013, 11:38 PM
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I spoke to Audio Authority on the phone today an told a CSR what we were trying to do. He said they have equipment for that purpose, and some of it is very capable stuff - capable of handling up to 2500 watts per channel and switching actively. The CSR said he would get back to me via e-mail with appropriate part numbers and a direct quote. That equipment is a cool find Andrew!

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post #59 of 186 Old 05-23-2013, 07:42 AM
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Jonathan,

Hugh here.

Got your email about borrowing one of our Melody amp.

I have not got time to read through the whole thread but can you tell me what Pre are you using?

Thanks,

Hugh
Angel City Audio
Melody US Distributor
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post #60 of 186 Old 05-23-2013, 08:56 AM
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Hugh,

We will be using my emotiva usp-1 as of now.
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