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Receivers, Amps, and Processors

jmit115's Avatar jmit115
04:46 PM Liked: 10
post #91 of 254
04-24-2011 | Posts: 64
Joined: Mar 2011
Thanks Mike:
I would think that for double the price there would have to be some advantages over the lower priced unit's. IDK
MichaelJHuman's Avatar MichaelJHuman
01:00 PM Liked: 125
post #92 of 254
04-25-2011 | Posts: 18,999
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IMO, Price is a tricky thing in audio. Some gear has a very limited market near as I can tell.

I know many, many people who don't even own a receiver (they have boom boxes, or iPods, or computer speakers maybe, but no receiver.)

I have no idea, but maybe less than one in ten americans owns a receiver, AV, or otherwise. Does not seem far off when thinking of people I know (and not being a jerk, but I tend to know more middle class people than lower class - not a knock against anyone.)

Out of all my friends I only know a few who own amps meant for home audio (a few may own guitar amps.)

I have to speculate the home amp market is small. And diluted. There are many companies making home amps.

That drives the price up, obviously. Some pricing in amplifiers is due to the limited market. Some is due to expensive amp designs, and some may be padding (after all, if you are going to charge $10,000 for an amp, why not charge $15,000, as your customers are probably wealthy - just a guess on my part

Now I assume Emotiva figured out some way to make money selling affordable amps (this does not mean low quality.) Internet direct helps I would guess. Perhaps limited advertising. Finding a place that could make them cheaply. Etc. If done right, I would guess the idea was that a lower price could generate more sales. All guesswork. But basic business reasoning I believe.

Sure, there are better performing amps. Noise for example. I am sure there are quiter amps. And there are certainly amps using better parts. The tough question is sound. And you can read about all the amp sound debates. But no one has ever proven to me that a conventional class AB amp, compentently made will sound much different than another competently made class AB amp, providing neither is overdriven.

And obviously you pay more for more power to some extent - but you rapidly hit the law of diminishing returns in my book. If you have 200 watts / channel, doubling that to 400 watts / channel is a 3 dB change in SPL - which is small (you can hear this for yourself, by adjusting your receiver's volume by 3 dB)
CatTre's Avatar CatTre
11:43 PM Liked: 10
post #93 of 254
04-30-2011 | Posts: 110
Joined: Nov 2010
Thanks Michael J Human

Very informitive. I have been considering adding an amp to my setup and I needed more information when I stumbled across your thread.

So based on your thread here I could use a 50watt amp to power efficent speakers for a small to med size room. If I had a large room with vaulted celiengs then a 100watt amp would do.

Now if I had very inefficent speakers a 100watt amp would do a small room and a larger amp for larger rooms.

This is my understanding at this point of my learning curve, please correct me if I am wrong.

Thanks
MichaelJHuman's Avatar MichaelJHuman
06:52 PM Liked: 125
post #94 of 254
05-01-2011 | Posts: 18,999
Joined: Nov 2006
You will get better answers asking general amp questions outside the thread as not everyone reads this.
Gellidius's Avatar Gellidius
06:49 AM Liked: 16
post #95 of 254
05-03-2011 | Posts: 581
Joined: Mar 2007
Michael, this is very interesting reading on your first post but i would like to suggest a correction.
You say that every doubling of distance from the speakers decreases the SPL by 6 dB;
i think that this is exact for anechoic spaces, but for a home living room, it should be more like 3 dB's or so, depending on the size of the room and it's type of construction.

Very large rooms will have a comparatively (all else being equal) higher drop in SPL than small rooms.

The reason for this is the fact that sound in a room does not get lost in infinite space like in an anechoic room or outside on top of a pole, but is bounced back to the room by the room boundaries (walls/floor/ceiling).
Most of the loss happening in a room will then come from those reflecting surfaces absorbing a certain percentage of the sound, but will never approach the loss happening in open spaces or anechoic conditions.

Do you agree to that?

Have a nice day! :-)
MichaelJHuman's Avatar MichaelJHuman
08:46 AM Liked: 125
post #96 of 254
05-03-2011 | Posts: 18,999
Joined: Nov 2006
Probably a good point. But I would think the specifics on that would depend on room acoustics? A room with more sound absorption would damp reflections, reducing reinforcement and such, right?

I found a cool graph showing the effect of room reinforcement vs inverse square loss from direct propagation. I would assume this was based on actual measurements and could vary depending on various factors. According to the graph, fall off in SPL stops obeying inverse square loss beyond one meter from the source. It actually 'flattens" out from 4 to 8 meters. Interesting stuff.

Perhaps I just just say that actual loss will not match inverse square loss in real rooms due to the fact that normal rooms will reflect the sound waves back to the listener.

http://books.google.com/books?id=9e-...20loss&f=false
Gellidius's Avatar Gellidius
11:12 AM Liked: 16
post #97 of 254
05-03-2011 | Posts: 581
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you say essentially the same thing as me, and i agree with you.

i wrote in my previous post: "...depending on the size of the room and it's type of construction."
The type of construction i was referring to includes sound absorptive material of any kind.

i would add only one thing; in a room, the loss in SPL should almost never be as much as 6dB; it that would happen, it would be caused by such heavy sound absorption that the room would, in effect, be an anechoic room and all but unusable for enjoying A/V.
MichaelJHuman's Avatar MichaelJHuman
05:49 PM Liked: 125
post #98 of 254
05-03-2011 | Posts: 18,999
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All good points. I will try to take the time to correct that info. Surprised no one took me to task for this before.
Brenttom's Avatar Brenttom
03:56 PM Liked: 10
post #99 of 254
05-26-2011 | Posts: 11
Joined: May 2011
a balance of absorbtion and reflection is required - in-room specifications will always be higher than anechoic
MichaelJHuman's Avatar MichaelJHuman
04:26 PM Liked: 125
post #100 of 254
05-26-2011 | Posts: 18,999
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I don't debate that point whatsoever. I think the point was about losses being lower. I think most savvy audio fans know that a 93 dB in room speaker is more like a 90 dB anechoic speaker.

What seems less known is that reduction in SPL loss vs distance behaves differently in room.
BAdz's Avatar BAdz
11:47 AM Liked: 10
post #101 of 254
06-03-2011 | Posts: 103
Joined: Jan 2007
It has been an absolute pleasure to read this OP as well as many of the later Q&A posts. I have a Denon AVR2808 and I have been contemplating whether I should be looking to upgrade my speakers next, or if I should upgrade to a separate amp for the fronts and use the Denon for only the rears, and this thread really helped me learn and understand what exactly to look for in an amp, and what the numbers really mean when comparing.

I'm now starting to think the amp is a better idea to start with because on top of any clarity I may hope to gain from my existing system, I think moving forward an amp will prove useful no matter which direction I decide to move next.
MichaelJHuman's Avatar MichaelJHuman
11:51 AM Liked: 125
post #102 of 254
06-03-2011 | Posts: 18,999
Joined: Nov 2006
Glad it helped
playaj's Avatar playaj
06:31 PM Liked: 10
post #103 of 254
06-09-2011 | Posts: 113
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Thank you for this post.
russ_777's Avatar russ_777
08:24 PM Liked: 20
post #104 of 254
06-14-2011 | Posts: 270
Joined: Jan 2005
Just wanted to say great job by OP on this FAQ. It's written in layman's terms so that most readers who don't have advanced EE degrees can readily understand the points...not necessarily easy to do.

A few observations & comments for your consideration:

1. I would add to your factors determining needed PA power: typical ambient noise level in listening room; the type of source material you typically listen to (well recorded symphonic music usually has much higher dynamic range than rock or pop music); the type of loudspeaker (planar/dipole speakers do not follow the inverse square law); and the minimum impedance of your speaker.

2. On the last point, I think buyers can get too reliant on the nominal impedance rating of loudspeaker systems. In reality, the input impedance of most all systems varies greatly with frequency, both in magnitude and phase angle. If your speaker system impedance curve has substantial dips below 4 ohms, you'd better know that your PA can supply the corresponding current, even if only for a few 10s of msecs. A PA whose max power rating may appear sufficient on the surface may be inadequate if it is current limited for the volume peaks you wish to listen to with high energy transients in those frequency bands.

3. While I agree that the ACD spec is a good and necessary measure of a PA's maximum steady state capability, we don't listen to constant amplitude sine waves. Especially for source material with wide dynamic range, and with very inefficient speakers in large rooms, the transient capabilities of a PA become very important. One of my older systems consists of Carver Amazing panel speakers which are indeed very inefficient. When I originally purchased them many years ago, PAs and receivers rated in excess of 200 wrms/ch would clip when listening to symphonic music on these speakers at high levels. I ended up buying a Class G PA available at the time which, although rated at "only" 100 watts rms/CH, was measured as delivering up to 1800 watts into 2 ohm loads for 25 msec -- something the other "more powerful" 200+ watt PAs could never begin to approach. The Proton PA was the perfect match for these speakers, as I could drive the speakers to prodigious undistorted SPLs for a few 10s of msecs with the right recording...which happens to be about how long most musical transients last. Moral of the story is ACD rms doesn't tell you anything about how the PA will behave playing music unless the peak output remains below the max rms value.
MichaelJHuman's Avatar MichaelJHuman
09:10 PM Liked: 125
post #105 of 254
06-14-2011 | Posts: 18,999
Joined: Nov 2006
Good feedback

1. There is no doubt that you need more power to overcome background sound, but for most cases this won't matter I think. I agree that the type of material definitely changes your needs. Playing back classical full orchestral music is very demanding dynamically speaking. Playing back pipe organ music might be tough on some amp/speaker combos. Playing back highly compressed rock music at lease wrecking volumes probably requires good heat sinking and protection mechanisms to keep your amp alive.
2. Right. I forget what the article says about impedance differering with frequency - I usually mention that when I talk about impedance. I probably don't mention phase angle. It probably suffices to say some speakers are harder to drive than others (there's a good article on the technical details you mention (http://www.stereophile.com/reference...avy/index.html)
3. ACD is always a fun discussion. What I think is important, is not ACD per se. But the fact that some receivers (and maybe some really crappy amps) who's specs seems pretty similar turn out to have quite different behavior under load. Some totally collapse, their specs being a funny joke. Driving the receiver/amp with all channels driven in a bench test is one way to show this.)
fyzziks's Avatar fyzziks
12:14 PM Liked: 10
post #106 of 254
06-15-2011 | Posts: 1,512
Joined: May 2007
Quote:
Originally Posted by MichaelJHuman View Post

Probably a good point. But I would think the specifics on that would depend on room acoustics? A room with more sound absorption would damp reflections, reducing reinforcement and such, right?

I found a cool graph showing the effect of room reinforcement vs inverse square loss from direct propagation. I would assume this was based on actual measurements and could vary depending on various factors. According to the graph, fall off in SPL stops obeying inverse square loss beyond one meter from the source. It actually 'flattens" out from 4 to 8 meters. Interesting stuff.

Perhaps I just just say that actual loss will not match inverse square loss in real rooms due to the fact that normal rooms will reflect the sound waves back to the listener.

There's a graph of actual data in Toole's book "Sound Reproduction" on p. 60, Chapter 4. It clearly shows a loss of SPL with distance of -3dB/DoubleDistance from several living rooms. The data is from a report by T. J. Schultz, "Improved Relationship between Sound Power Level and Sound Pressure Level in Domestic and Office Spaces" combined with some of Toole's own data. The loss curve seems very robust to room type and source type once you get past 1m.

As a side note, I would suggest anyone serious about HT to read Toole's book. It's an eye-opener.
MichaelJHuman's Avatar MichaelJHuman
10:51 AM Liked: 125
post #107 of 254
06-16-2011 | Posts: 18,999
Joined: Nov 2006
I need to update the section given that info, thanks.
grahamsk's Avatar grahamsk
11:29 AM Liked: 10
post #108 of 254
06-27-2011 | Posts: 2
Joined: Jun 2011
Help. Hi i have a Yamaha RX-V1700 Receiver which has suddely lost all power, totally dead. i have changed fuse on the main plug but no luck. is there an internal fuse that is easily accessable? Any other suggestions to get sorted
MichaelJHuman's Avatar MichaelJHuman
12:37 PM Liked: 125
post #109 of 254
06-27-2011 | Posts: 18,999
Joined: Nov 2006
I have seen the service manual before. I seem to recall a few fuses. The transformer could have a cut out as well, which, if true, and if that's the problem, it's probably a replacement. I would ask this question in the main thread.

As a reminder, this thread is best used only for comments on the FAQ. You will get more responses by posting to one of the sub forums.
Mkard's Avatar Mkard
11:46 PM Liked: 14
post #110 of 254
06-28-2011 | Posts: 559
Joined: Dec 2008
Quote:
Originally Posted by MichaelJHuman View Post

I have seen the service manual before. I seem to recall a few fuses. The transformer could have a cut out as well, which, if true, and if that's the problem, it's probably a replacement. I would ask this question in the main thread.

As a reminder, this thread is best used only for comments on the FAQ. You will get more responses by posting to one of the sub forums.


MichaelJHuman and contributors:

This is a great thread. Fantastic start and then some really good stuff that attempts to civilize us savages follows. Thanks to all, especially MichaelJ.

In other news: A Vatican Spokesman Father Arrivederci today announced the formation of a Babel Commission whose stated goal is to begin beatification process of one MichaelJHuman whose unflagging efforts to audibly uplift the sonically downtrodden has saved many. And much.
The distinguishing characteristics of this soon to be noted saint of the Audiophilic Universal Belief (from which The All Resounds) have been shown to be extensive knowledge of this Wondrous World of Aural Phenomena, a willingness to extend himself in the delivery of this Knowledge in a conversational and accessible tone, and in a manner otherwise truly appreciative of said Wonders.
The success of this long awaited AVS beatification campaign is assured due to the proven and documented occurrances of "Extraordinary Patience" when confronted by by the dumbfounded, deluded and even the oft-repeated appearances of the dedicated (and much feared) OBLIVIOUS ONE, who comes in many guises. These miracles have been witnessed by hundreds, nay thousands of the aVsaithful and will assuredly yield reward in all of the Worlds.

Back to our regularly scheduled programming..

Sincerely,

MKard ---
Nosferatu's Avatar Nosferatu
06:32 AM Liked: 28
post #111 of 254
06-29-2011 | Posts: 553
Joined: Jan 2004
EDIT: Read the whole article...saw you getting frustrated at others posting questions in the thread but too late

Anyways, informative FAQ thanks for taking the time to put it together. I'll leave my original post here below alone if you care to comment that's fine, if not no biggie.

hey I enjoyed reading this (actually I still am) but had a question in terms of what the receiver can really output. I read the section where you state they artificially inflate the total power of the receiver (e.g. 135 watt X 7) as in the unit isn't likely sending this much power to all 7 at once so how would you interpret this from the website...they list each channel somewhat separately and don't necessarily claim it as all at once.

Onkyo TX-NR807
http://www.onkyousa.com/model.cfm?m=...s=Receiver&p=s

Front L/R 135 W + 135 W (8 ohms, 20 Hz–20 kHz,
0.08%, 2 channels driven, FTC)

Center 135 W (8 ohms, 20 Hz–20 kHz, 0.08%,
2 channels driven, FTC)

Surround L/R 135 W + 135 W (8 ohms, 20 Hz–20 kHz,
0.08%, 2 channels driven, FTC)

Surround Back L/R 135 W + 135 W (8 ohms, 20 Hz–20 kHz,
0.08%, 2 channels driven, FTC)

Dynamic Power 300 W (3 ohms, 1 ch)
250 W (4 ohms, 1 ch)
150 W (8 ohms, 1 ch)

THD (Total Harmonic Distortion) 0.08% (Rated power)

Signal-to-Noise Ratio 110 dB (Line, IHF-A)
MichaelJHuman's Avatar MichaelJHuman
01:53 PM Liked: 125
post #112 of 254
06-29-2011 | Posts: 18,999
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I would read it based on this line...

Front L/R 135 W + 135 W (8 ohms, 20 Hz–20 kHz,
0.08%, 2 channels driven, FTC)

That seems straightforward. Per FTC rules (as I understand them,) the amp can put put 135 watts at full bandwidth into an 8 ohm dummy load for 5 minutes (after a preconditioning period at 1/4 power.)

That's all we can know without bench tests. Power when playing back, say a movie is impossible to predict IMO. THX tells us that movies don't use all channels equally. So you don't need full power to all channels at all times. But during a big action scene, you can bet that all those channels will be demanding a lot of power. At some point the power supply will fail to keep up, or limiter circuits will activate or both (I really don't know.) At that point the receiver will start distorting due to clipping. My guess is that average SPL will be quite high at point of clipping with most receivers for reasons explained in the FAQ.
Hugme1's Avatar Hugme1
02:08 PM Liked: 10
post #113 of 254
06-29-2011 | Posts: 237
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Quote:
Originally Posted by MichaelJHuman View Post


That seems straightforward. Per FTC rules (as I understand them,) the amp can put put 135 watts at full bandwidth into an 8 ohm dummy load for 5 minutes (after a preconditioning period at 1/4 power.)
.

Per 1 channel ?? That's how I read it am I wrong?
MichaelJHuman's Avatar MichaelJHuman
04:38 PM Liked: 125
post #114 of 254
06-29-2011 | Posts: 18,999
Joined: Nov 2006
In this case, they are talking two channels. And in my experience, most receivers have no problems holding their rated power into two channels.
SAVholic's Avatar SAVholic
03:16 PM Liked: 17
post #115 of 254
07-05-2011 | Posts: 804
Joined: Jun 2006
I'm thinking about adding an amp to my RX-V1800 before the end of the year... but is the RX-V1800 "enough" (pre-out section) to add and amp like an emotiva or outlaw or should I consider upgrading to a mid-price newer AVR as well. I don't "need" HDMI 1.4 or 3D for now I just want to be in the separates league. Thanks!
MichaelJHuman's Avatar MichaelJHuman
07:46 PM Liked: 125
post #116 of 254
07-05-2011 | Posts: 18,999
Joined: Nov 2006
You will get better answers asking general amp questions outside the thread as not everyone reads this.

The 1800 would make a fine pre-amp in my opinion. I use the Z7, which is very similar.
cougar75's Avatar cougar75
10:01 AM Liked: 20
post #117 of 254
07-07-2011 | Posts: 343
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Quote:
Originally Posted by MichaelJHuman View Post

And obviously you pay more for more power to some extent - but you rapidly hit the law of diminishing returns in my book. If you have 200 watts / channel, doubling that to 400 watts / channel is a 3 dB change in SPL - which is small (you can hear this for yourself, by adjusting your receiver's volume by 3 dB)


But are there not OTHER distinct advantages provided by the additional power than just volume that justify going with more power?

cougar
MichaelJHuman's Avatar MichaelJHuman
03:17 PM Liked: 125
post #118 of 254
07-07-2011 | Posts: 18,999
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Quote:
Originally Posted by cougar75 View Post

But are there not OTHER distinct advantages provided by the additional power than just volume that justify going with more power?

cougar

Not that I know of.

Check out the distortion vs power graph in this link. As you can see, the distortion is lower at less power output. All amps should have a similar looking graph. More power = less distortion, all other things being equal

http://www.emotiva.com/specs/XPA-3%208ohm.pdf
cougar75's Avatar cougar75
03:57 PM Liked: 20
post #119 of 254
07-07-2011 | Posts: 343
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Quote:
Originally Posted by MichaelJHuman View Post

Check out the distortion vs power graph in this link. As you can see, the distortion is lower at less power output. All amps should have a similar looking graph. More power = less distortion, all other things being equal.

http://www.emotiva.com/specs/XPA-3%208ohm.pdf



Did you get that last sentence right?
MichaelJHuman's Avatar MichaelJHuman
03:58 PM Liked: 125
post #120 of 254
07-07-2011 | Posts: 18,999
Joined: Nov 2006
Yes, why?

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