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Re: How much power is needed to play M80s at reference
bdpf #339199 02/19/11 07:57 PM
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Dan, by your own suggestion, it might be the best idea to go with the M22s/Klipsch equivalent bookshelf, since you can always switch them to rear channels(7.1) once you decide or are able to go with towers up front. You may feel towers are unneccessary in the end scheme of things but knowing you have the option of using them as rears may make your decision easier.


Half of communication is listening. You can't listen with your mouth.
Re: How much power is needed to play M80s at reference
bdpf #339206 02/19/11 09:02 PM
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Originally Posted By: bdpf

It looks like you are over analyzing everything. No matter how much you read, it will be no substitute for hearing the speakers. I know that it might be difficult in your case but as others have said, the M22s and even the M2s will be representative of the Axiom sound and as for Klipsch, you might be able to listen to them at the dealer. Good luck.


Well, sounds like the M22s it is. For Klipsch, I will buy their equivalent bookshelf so I can have them both in my room so that I can listen back to back. I've been to dealers but between differences in rooms and audio memory, I'll just have to have them both and try them both out. Bookshelves can be shipped APO, so the shipping issue will not be an issue.

How do you think I should set it up? I'm thinking I'll hook one set up to the front outputs, and the second set will be hooked to the B zone outputs. Everything will be level matched, and I'll cross them both over at 80Hz, above their cutoff, so that the differing bass extension will not be an issue. I will assure the reciever's settings are identical for both speakers with the exception of distance. I'll try to get them both acoustically centered. I'll set them up in an AB AB configuration so that they both have identical spacing. Before critically listening, I'll work on positioning both sets for optimum soundstage. I'll also have friends over to listen to try to overcome any bias I may have on my part. Heck, I'll even try to get the same color and have my wife make the connections to the speakers so that I don't know which ones are playing. I want to try to make the playing field as level and objective as possible.

Any other recommendations?

Seem like a lot to go through to make a decision? Maybe. But I'm a geek - I love this type of thing!

The wait is gonna kill me... (not literally, I hope) 5 more months in Afghanistan (hence why I have so much time to think about this kind of stuff), then a new baby in Sept, then hopefully by January, time to make it happen! At least I'll have plenty of time to select sample music and movie scenes!

Re: How much power is needed to play M80s at reference
DanLW #339211 02/19/11 10:12 PM
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Initially I would set them up strictly as stereo pairs, one set Axiom then the Klipsch. Play some music with each set and take notes as to what you are hearing, ie, too much treble, muffled midrange etc. be sure to try varying music styles. Once that is done sit back and read your notes, you might be surprised by what you are hearing between the different speakers. I would then do an A/B comparison as you are suggesting to really hammer home the differences or similarities. One suggestion would to have some else switch between the 2 speakers on the amp without the listener knowing which set is on, this makes it about as blind of a listening test as possible without going through coverings for the speakers etc.


Jason
M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70
Re: How much power is needed to play M80s at reference
DanLW #339253 02/20/11 04:51 AM
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Dan, first let me express our thanks to you for the service that you're rendering our country and extend best wishes to you and your wife for the upcoming arrival of your new baby.

Your plan to test the Axiom and Klipsch sounds good, but I'd suggest that the RB-61II would be a closer match to the M22 in overall size and cost. Yes, a key difference will be the significantly higher sensitivity of the Klipsch, and you're aware of the necessity for level-matching. Your setup description sounds fine, but I didn't follow why the distance settings would be different.

I was going to respond re the Crown calculator in your other thread, but was delaying because you'd indicated that you might have time to test with an SPL meter, and those results might be interesting. Although I didn't doubt the findings of Dr. Toole and other authorities on the point, I did check for myself a couple years ago. If you'll able to do this at least at 1, 2 and 4 meters you may be surprised to find that the reduction in sound level is indeed far less than would result from applying a 6dB per doubling of distance formula, which is of course theoretically correct, but applies only to an omni-directional sound source in an anechoic environment.

Of course, the Crown calculator is mathematically "correct" in performing the simple calculations under that formula, but as was said, that isn't the real world of home audio. You may not have read the more extended Crown discussion of power requirements published in conjunction with the calculator here . It clarifies the point that the calculator results don't apply to listening rooms at home as distinguished from professional applications out-of-doors, but unfortunately that rather key point is somewhat buried near the end under "Other considerations". They suggest adding a 6dB correction to the results, which you'll note would reduce the calculator's number to 1/4th of its previous value(Axiom uses 4dB for a similar purpose in its sensitivity ratings). Then(can't imagine why)instead of suggesting that an amplifier with 1/4th the power rating would be sufficient, they suggest that another "headroom"(already accounted for by the 105dB or whatever max is to be used, of course)be added on.

In brief, you appear to be too concerned with the power question. Clean power is cheap and plentiful these days and both the principles of audio technology and personal experience indicate to me that typical receivers rated anywhere in the 100-150 watt area are ample for all safe sound levels with speakers such as Axioms(even that 5 watt tube amp which Alan derisively commented on might work with those Klipsch sensitivities).


-----------------------------------

Enjoy the music, not the equipment.


Re: How much power is needed to play M80s at reference
JohnK #339265 02/20/11 10:12 AM
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Originally Posted By: JohnK
Dan, first let me express our thanks to you for the service that you're rendering our country and extend best wishes to you and your wife for the upcoming arrival of your new baby.


Thanks! I wasn't really mentioning my sitation because I want any special recognition, I was just trying to express why the ultimate comparison is almost a year into the future. But thanks all the same!

Quote:
Your plan to test the Axiom and Klipsch sounds good, but I'd suggest that the RB-61II would be a closer match to the M22 in overall size and cost. Yes, a key difference will be the significantly higher sensitivity of the Klipsch, and you're aware of the necessity for level-matching. Your setup description sounds fine, but I didn't follow why the distance settings would be different.


My current receiver (and hopefully the new one I plan to get - Yamaha RX-V1900) has an audible speaker distance fine tune (maybe it's delay) Where it plays a short tick on both fronts. Sitting in the listening position, I can hear whether it's left or right of center. The setting is adjusted so that the tick sounds like it's coming from exactly inbetween the front speakers. I figure I will do this with both sets to help eliminate localizability (is that a word?) of which pair is playing.

Quote:
I was going to respond re the Crown calculator in your other thread, but was delaying because you'd indicated that you might have time to test with an SPL meter, and those results might be interesting.


Once I get home (in 5 months), and once I have get my treatments finished, I will do that test. I suspect it will be more than 3db per doubling, but less than 6db. Perhaps 4db? I know that even with just the front wall treated, there is definite absorption going on. The room is noticeably quieter. (less echoey)

Quote:
Although I didn't doubt the findings of Dr. Toole and other authorities on the point, I did check for myself a couple years ago. If you'll able to do this at least at 1, 2 and 4 meters you may be surprised to find that the reduction in sound level is indeed far less than would result from applying a 6dB per doubling of distance formula, which is of course theoretically correct, but applies only to an omni-directional sound source in an anechoic environment.


What numbers did you come up with? Was this a treated room? If it was, I'd be very interested in the results.

Quote:
...but unfortunately that rather key point is somewhat buried near the end under "Other considerations".


I see, a fine print error.

Quote:
In brief, you appear to be too concerned with the power question. Clean power is cheap and plentiful these days and both the principles of audio technology and personal experience indicate to me that typical receivers rated anywhere in the 100-150 watt area are ample for all safe sound levels with speakers such as Axioms(even that 5 watt tube amp which Alan derisively commented on might work with those Klipsch sensitivities).


Over on the Klipsch forum, somebody did relate an experience where he drove his RF-7s with a 50W amp, and it sounded better than with a different 200W amp. The context was that it was a very very nice 50W amp capable of meeting the RF-7s current requirements. Apparently there's a point in the impedance curve where the RF-7 drops down to somewhere between 2 and 3 ohms. It's somewhere around 180hz. So for them to sound nice you either use brute force with a 300W amp capable of delivering lots of amps in the first place, or you get a really really nice low power amp from a boutique store.

An update on the comparison, the Klipsch side is throwing yellow flags on the field. The Rf-7's tweeter and horn are larger than the RB81s (1.75" vs 1"), and as such, it is crossed over at a different frequency. Whereas the RB81 is crossed at 1400Hz, the RF-7 is crossed at 1200Hz. As one user put it, "it definitely improves the clarity and impact of the midrange/treble". Another user said that the RB81s may not give me an accurate representation of the RF-7s, and that the RB-75 (discontinued) would be a better match. The RB75 had the same size compression driver that the original RF-7 had, and was meant to provide RF-7 sound to those who didn't have RF-7 space. However, the tweeter was attenuated to keep it from stomping all over the RB75's single 8" driver (after all, the tweeter was designed to keep up with two 10" woofers)

I expressed to them that I will not be looking at low frequency extension, nor would I be SPL drag racing them, as towers are certainly capable of higher outputs. But I fear they may have a valid point in that the RB81s may not be a good representative for the RF-7s sound...

Re: How much power is needed to play M80s at reference
DanLW #339297 02/21/11 02:58 AM
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I say you skip all the deliberations, buy a honkin' big amp and the M80s and report back here after the setup has been hooked up and tested. grin


Fred

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Blujays1: Spending Fred's money one bottle at a time, no two... Oh crap!
Re: How much power is needed to play M80s at reference
DanLW #345946 04/24/11 05:27 AM
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Carver amps are on e-bay often. I have 3.
TFM-45 375 Wats into 8 ohms
500 into 4 ohms
1000 bridged mono

These are smooth, silent amps.


Axiom Epic 80 500 QS8s
Carver TFM-55 TFM-45 TFM-35
Rotel RSP 1068
Audiobytes/W amp & sub
M22s Ep125
Re: How much power is needed to play M80s at reference
bruceg #345947 04/24/11 05:45 AM
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Axiom Epic 80 500 QS8s
Carver TFM-55 TFM-45 TFM-35
Rotel RSP 1068
Audiobytes/W amp & sub
M22s Ep125
Re: How much power is needed to play M80s at reference
bruceg #345953 04/24/11 01:14 PM
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wow .5% THD that isn't very good.


M80s VP180 4xM22ow 4xM3ic EP600 2xEP350
AnthemAVM60 Outlaw7700 EmoA500 Epson5040UB FluanceRT85


Re: How much power is needed to play M80s at reference
SirQuack #345955 04/24/11 02:15 PM
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according to many different double blind tests that have been conducted through the years, people cannot differentiate between 0.5% THD and 0.00025% THD.
i can't give references, but i would not be surprised if some of those had been done by the NRC.

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