How to Choose a Loudspeaker -- What the Science Shows - Page 125 - AVS Forum | Home Theater Discussions And Reviews
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post #3721 of 4475 Old 07-15-2019, 08:13 AM
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Originally Posted by l0nestar8 View Post
...
I used to own an Infinity Primus system (362's and 152's.) I bought them because of their measured accuracy and because I hated my Polk Monitor II's. I sold them fast because the tweeters were horrible. They had the classic metallic "zing" sound that was always irritating. ...
I've read interviews with speaker designers where they say the material that a cone or dome is made out of couldn't possibly physically matter, as long as it's not operating in a range where it's resonating or breaking up. Thoughts?

Would be curious to hear from Dr. Toole or Mr. Voecks about why so many people might think the Infinity Primus floorstanders sound harsh or shrill when they have almost perfect spinoramas. How would such a thing be possible?
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post #3722 of 4475 Old 07-15-2019, 08:22 AM
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Originally Posted by Soulburner View Post
In order from steep to shallow:



Line-In, 24dB slope

Line-In, 12dB

LFE-In, 12dB
I will have to read up a bit more. I don't understand why line in and LFE in have different slopes.
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post #3723 of 4475 Old 07-15-2019, 08:30 AM
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Originally Posted by PhilharmonicDennis View Post
Thanks very much Dr. Toole. That was very helpful. I didn't know that your Soundpower measurement isn't very predictive of subjective rankings. That doesn't surprise me given my own experience with various measurements and perceived speaker quality. Consumer Reports was obviously over their heads when it came to loudspeakers, and now I have a better idea why.
I believe Dr. Toole had some other examples in his book of speaker manufactures trying to make the sound power curve flat. Which, due to directivity, normally results in the listening window being a rising curve and the speakers will be very bright. I don't think Consumer Reports necessarily had this problem because they used the subjective correction factor. I think their numeric accuracy fit was a delta from the ideal subjective curve based on sound power. This could have worked OK, but due to the 1/3 octave, I think the result was the overall flatness to the ideal curve was effectively weighted higher than any local variations.
When I was a lot younger I bought the Advent Legacy IIIs based on their data (and they were reasonably priced). I think by Spinorama standards these are likely to look poor around the crossover.

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post #3724 of 4475 Old 07-15-2019, 08:49 AM
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I will have to read up a bit more. I don't understand why line in and LFE in have different slopes.
It has to do with the LFE-in having greater bandwidth.

And I'm not saying the exact setting I ended up with this time will be best for everyone. We'll see if I end up with that or the middle slope next time I re-do the system. But I'm fairly certain I won't prefer the shallow slope.

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post #3725 of 4475 Old 07-15-2019, 09:51 AM
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Originally Posted by aarons915 View Post
I agree with this but I also agree that for many people who don't want to measure and EQ their response, 80Hz is a good crossover. If you have a ragged sub response with peaks above 100Hz or your sub is 5-10 db higher than your mains, then localization could happen.

I was reading any study I could find on sub localization in the AES journals and summarized 4 of them in this thread:
https://www.avsforum.com/forum/91-au...n-studies.html

The lowest crossover frequency needed in any of the studies was 100Hz and not surprisingly, a single sub located in a corner was the easiest to localize, but still not at 100Hz crossover. A very early study made the claim that there is "Very little directional information below about 200Hz" and "none at all below about 100Hz."

I recently did my own little test in my room to check that claim, I use dual subs but I actually turned 1 off because it's easier to localize the bass laterally if the bass is coming from 1 source. I had to turn the crossover up to 250Hz before it was easy to localize. I was surprised that even at 200Hz I couldn't localize the bass or at least it wasn't easy to tell.

I personally use a 100hz 4th order crossover and wouldn't go higher than that though, mostly because it's not necessary in my opinion. Above 100hz the mains sound a bit too thin and I also don't want vocals coming from the sub, even if they aren't localized, it just feels wrong. 100Hz is about the highest I can go before I can hear the lower end of the vocals (with my mains off). If I had towers, I would most likely cross at 80Hz but I think those of us with single driver bookshelf speakers are better off at 100Hz. This is all with 4th order slopes, if had a receiver with a 2nd order high pass, I would be at 120Hz probably.
Interesting set of experiences. We should expect different results from different speaker setups, environments and people. For example, with higher crossovers the sub needs to be capable of playing cleanly enough at higher frequencies so that the overall system sound is enhanced rather than deteriorated. As long as we all acknowledge that there is some flexibility here we can understand how different people get different results. The main issue comes when someone (not you) comes along and tries to set ironclad rules for sub crossover points that don't fit with the experiences of others.
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post #3726 of 4475 Old 07-15-2019, 05:25 PM
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Question for Dr. Toole

I have a question for Dr. Toole.

I have read through the companion website for your book (https://routledgetextbooks.com/textb...me-theatre.php) and have a question regarding “Designing a Home Theater: Part 3: Section 6: Estimating Amplifier Power Requirements for Home Theaters”.

Figure 7 shows a graphical representation of the “dB difference” and “Continuous Amplifier Power (watts)”. Based on your suggested calculations, I have determined that my speakers have a dB difference of just under 20dB (19.8db). My speakers are nominally closest to 4ohms, which would mean I would require approx. 200 watts of continuous power.

However, have external subwoofers that handle bass below 80Hz, and my front left and right speakers have their own internal amplifiers that power the bass sections (approx. 150Hz and below). So my question is: would these two factors change anything in these calculations?

As I understand it, the bass is what uses up most of the power anyways. So, would I still need 200 watts to achieve the same outcome in this scenario?
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post #3727 of 4475 Old 07-15-2019, 09:40 PM
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Turns out that after auditioning many different speakers (on different days, in different rooms, not volume matched, I know, I know, far from ideal) I have landed on Revel. And it'll probably be the F36. Today listened to that again along with the F206 (back to back, same room). While the F206 is probably the better speaker, to me the difference with F36 was only slight and not worth the extra cost. F36 also extends a bit deeper, though F206 bass probably a little tighter (but not a big difference).
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post #3728 of 4475 Old 07-16-2019, 06:51 AM
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Originally Posted by sakete View Post
Turns out that after auditioning many different speakers (on different days, in different rooms, not volume matched, I know, I know, far from ideal) I have landed on Revel. And it'll probably be the F36. Today listened to that again along with the F206 (back to back, same room). While the F206 is probably the better speaker, to me the difference with F36 was only slight and not worth the extra cost. F36 also extends a bit deeper, though F206 bass probably a little tighter (but not a big difference).
I have a pair of F36 Revel speakers in a room dedicated for music listening. I thought that they represented a tremendous value and am glad that I purchased them. I also have a 5.2 home theater system in another room based on the 228Be, but still use the F36s every day.

Please let us know what you end up purchasing. Thanks.
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post #3729 of 4475 Old 07-16-2019, 06:58 AM
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I have a pair of F36 Revel speakers in a room dedicated for music listening. I thought that they represented a tremendous value and am glad that I purchased them. I also have a 5.2 home theater system in another room based on the 228Be, but still use the F36s every day.
Have you ever put them head to head in the same room? If so, how would you describe the differences?

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post #3730 of 4475 Old 07-16-2019, 07:56 AM
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Originally Posted by Soulburner View Post
Have you ever put them head to head in the same room? If so, how would you describe the differences?
Interesting idea, but I have never put them into the same room to compare with each other.

In case you live near a Nebraska Furniture Mart, last night I discovered that they had a dedicated listening room with the Salon 2, and an adjacent dedicated room with the F228Be and F36. They also had a nearby large room with additional speakers. This would make it possible to quickly compare different models, such as the F228Be and F36. Or possibly you can find a local dealer that is set up for listening comparisons.
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post #3731 of 4475 Old 07-16-2019, 08:31 AM
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Interesting idea, but I have never put them into the same room to compare with each other.



In case you live near a Nebraska Furniture Mart, last night I discovered that they had a dedicated listening room with the Salon 2, and an adjacent dedicated room with the F228Be and F36. They also had a nearby large room with additional speakers. This would make it possible to quickly compare different models, such as the F228Be and F36. Or possibly you can find a local dealer that is set up for listening comparisons.
Having heard the F206 and F36 back to back in the same room myself, I'd guess the F228be would just have better dynamics, tighter bass, probably deeper extension and more presence because of the larger woofers. But it'll still mostly sound the same as the whole Revel line has the same tonality/timber, just a touch more refinement as you move up the price range. That's why I will probably settle on the F36 myself, as the differences between that and the F206 were pretty subtle and not something I'd want to shell out an additional $1.5k MSRP for. That money will now probably go to something else, maybe a sub to fill out the low end. And at some point a center, but that's not very important to me right now.
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post #3732 of 4475 Old 07-16-2019, 08:37 AM
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I have a question for Dr. Toole.

I have read through the companion website for your book (https://routledgetextbooks.com/textb...me-theatre.php) and have a question regarding “Designing a Home Theater: Part 3: Section 6: Estimating Amplifier Power Requirements for Home Theaters”.

Figure 7 shows a graphical representation of the “dB difference” and “Continuous Amplifier Power (watts)”. Based on your suggested calculations, I have determined that my speakers have a dB difference of just under 20dB (19.8db). My speakers are nominally closest to 4ohms, which would mean I would require approx. 200 watts of continuous power.

However, have external subwoofers that handle bass below 80Hz, and my front left and right speakers have their own internal amplifiers that power the bass sections (approx. 150Hz and below). So my question is: would these two factors change anything in these calculations?

As I understand it, the bass is what uses up most of the power anyways. So, would I still need 200 watts to achieve the same outcome in this scenario?
There is not a truly satisfactory answer to your question. The traditional measure of sound level used in system calibration is pink noise band limited to 500 Hz to 2 kHz - all middle frequencies. All else is extrapolated from this. In cinemas the signal is broadband pink noise measured using C weighting (a broadband metric that rolls off below 50 Hz and above 5 kHz). These are of course different, and neither properly weights the very low frequencies.

Eliminating the need to reproduce frequencies below 80 Hz will indeed reduce the power demands on the main speakers, but it is a small fraction of the total bandwidth so we are not talking about a large factor. If you stick with your 200 watt estimate, enjoy the security of having a small amount of headroom - never a bad idea.

Remember, those calculations were for cinema reference sound levels. I know of nobody who uses those levels for movies in domestic rooms. The resulting sound levels are dangerous to hearing and - in my opinion - too darned loud. In some films they are too loud even for cinemas - some turn the volume down as much as 10dB (1/10 power!) to keep customers from walking out. A main topic of discussion within SMPTE standards committees is how to tame the "loudness wars" that developed when soundtracks went digital and the full dynamic range could be used without distortion - it has been, encouraged by film executives standing at the back of the dubbing stage shouting "more".

Just a barely noticeable volume change of 3 dB reduces power demands by a factor of 2.
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post #3733 of 4475 Old 07-16-2019, 08:44 AM
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Interesting idea, but I have never put them into the same room to compare with each other.

In case you live near a Nebraska Furniture Mart, last night I discovered that they had a dedicated listening room with the Salon 2, and an adjacent dedicated room with the F228Be and F36. They also had a nearby large room with additional speakers. This would make it possible to quickly compare different models, such as the F228Be and F36. Or possibly you can find a local dealer that is set up for listening comparisons.
Seriously? Yes, there is one in Omaha. I will have to check that out!
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post #3734 of 4475 Old 07-16-2019, 08:50 AM
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Originally Posted by sakete View Post
Having heard the F206 and F36 back to back in the same room myself, I'd guess the F228be would just have better dynamics, tighter bass, probably deeper extension and more presence because of the larger woofers. But it'll still mostly sound the same as the whole Revel line has the same tonality/timber, just a touch more refinement as you move up the price range. That's why I will probably settle on the F36 myself, as the differences between that and the F206 were pretty subtle and not something I'd want to shell out an additional $1.5k MSRP for. That money will now probably go to something else, maybe a sub to fill out the low end. And at some point a center, but that's not very important to me right now.
I feel diminishing returns kicking in with these speakers. I am content with my carefully placed, summed and equalized subs, doing a far better job in the bass department. Therefore, I would be content with a stand-mount from higher up the line than I would trying to get bass out of a floorstander. The only exception is trying to avoid the floor bounce cancellation that can be an issue with woofers high off the floor. With that in mind, I have no doubt the F36 is a well-rounded speaker.

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post #3735 of 4475 Old 07-16-2019, 08:55 AM
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Originally Posted by Floyd Toole View Post
There is not a truly satisfactory answer to your question. The traditional measure of sound level used in system calibration is pink noise band limited to 500 Hz to 2 kHz - all middle frequencies. All else is extrapolated from this. In cinemas the signal is broadband pink noise measured using C weighting (a broadband metric that rolls off below 50 Hz and above 5 kHz). These are of course different, and neither properly weights the very low frequencies.

Eliminating the need to reproduce frequencies below 80 Hz will indeed reduce the power demands on the main speakers, but it is a small fraction of the total bandwidth so we are not talking about a large factor. If you stick with your 200 watt estimate, enjoy the security of having a small amount of headroom - never a bad idea.

Remember, those calculations were for cinema reference sound levels. I know of nobody who uses those levels for movies in domestic rooms. The resulting sound levels are dangerous to hearing and - in my opinion - too darned loud. In some films they are too loud even for cinemas - some turn the volume down as much as 10dB (1/10 power!) to keep customers from walking out. A main topic of discussion within SMPTE standards committees is how to tame the "loudness wars" that developed when soundtracks went digital and the full dynamic range could be used without distortion - it has been, encouraged by film executives standing at the back of the dubbing stage shouting "more".

Just a barely noticeable volume change of 3 dB reduces power demands by a factor of 2.
That's for certain how I handled it back when I went to movies, but I never left without telling them why.
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post #3736 of 4475 Old 07-16-2019, 09:03 AM
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That's for certain how I handled it back when I went to movies, but I never left without telling them why.
Perhaps if someone were the first one out, and got petition signatures RE: the movie being too loud, of those just leaving the theater. Delivered to management.

They aren't used to seeing that kind of collective feedback. It could make a difference.
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post #3737 of 4475 Old 07-16-2019, 09:05 AM
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The only exception is trying to avoid the floor bounce cancellation that can be an issue with woofers high off the floor.
The Fraunhofer Institute was researching acoustics for their new audio laboratory rooms, wondering whether carpeting was enough or whether additional absorption was needed at the first reflection points on the floor. 2" of absorption was enough to avoid the floor bounce cancellation. Measurements improved but listening tests told another story:
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3.1.4. Subjective room assessment:

Regarding the floor reflection, the audible influence by removing this with absorbers around the listener is negative – unnatural sounding. No normal room has an absorbent floor. The human brain seems to be used to this.
Indeed, the one early reflection our human hearing has always heard, even when we're not in a room (i.e., outdoors), is the floor bounce. No surprise things sound "unnatural" when it's not there.

https://www.iis.fraunhofer.de/conten...ms_AES7672.pdf
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post #3738 of 4475 Old 07-16-2019, 09:20 AM
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The Fraunhofer Institute was researching acoustics for their new audio laboratory rooms, wondering whether carpeting was enough or whether additional absorption was needed at the first reflection points on the floor. 2" of absorption was enough to avoid the floor bounce cancellation. Measurements improved but listening tests told another story: Indeed, the one early reflection our human hearing has always heard, even when we're not in a room (i.e., outdoors), is the floor bounce. No surprise things sound "unnatural" when it's not there.

https://www.iis.fraunhofer.de/conten...ms_AES7672.pdf
This is interesting. It makes sense as gravity-bound creatures that we are used to having a floor under our feet. However, I am unsure how this fits in with the (seemingly established) notion that broad horizontal dispersion and somewhat limited vertical was preferred by most listeners. I have previously read that absorption (carpet, rug, etc) on an otherwise hard floor improves sound quality, which corroborates that.

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post #3739 of 4475 Old 07-16-2019, 09:23 AM
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I have previously read that absorption (carpet, rug, etc) on an otherwise hard floor improves sound quality, which corroborates that.
Try it both ways to see if your personal preference lines up with what you've previously read or Fraunhofer's findings.

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post #3740 of 4475 Old 07-16-2019, 09:27 AM
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Try it both ways to see if your personal preference lines up with what you've previously read or Fraunhofer's findings.
Unfortunately I can not, as I am carpeted here.

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post #3741 of 4475 Old 07-16-2019, 09:31 AM
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Originally Posted by Floyd Toole View Post
There is not a truly satisfactory answer to your question. The traditional measure of sound level used in system calibration is pink noise band limited to 500 Hz to 2 kHz - all middle frequencies. All else is extrapolated from this. In cinemas the signal is broadband pink noise measured using C weighting (a broadband metric that rolls off below 50 Hz and above 5 kHz). These are of course different, and neither properly weights the very low frequencies.

Eliminating the need to reproduce frequencies below 80 Hz will indeed reduce the power demands on the main speakers, but it is a small fraction of the total bandwidth so we are not talking about a large factor. If you stick with your 200 watt estimate, enjoy the security of having a small amount of headroom - never a bad idea.

Remember, those calculations were for cinema reference sound levels. I know of nobody who uses those levels for movies in domestic rooms. The resulting sound levels are dangerous to hearing and - in my opinion - too darned loud. In some films they are too loud even for cinemas - some turn the volume down as much as 10dB (1/10 power!) to keep customers from walking out. A main topic of discussion within SMPTE standards committees is how to tame the "loudness wars" that developed when soundtracks went digital and the full dynamic range could be used without distortion - it has been, encouraged by film executives standing at the back of the dubbing stage shouting "more".

Just a barely noticeable volume change of 3 dB reduces power demands by a factor of 2.
Thank you for your response. The problem is, if I want to have “peace of mind”, so to speak, it will cost me about $2,000. No small price to pay for something that may or may not make a difference.

I was wondering if I could employ a different method to help determine my needs.

My current receiver outputs 100 watts per channel (full band 20hz-20khz, two channels driven). Based on the chart, 100 watts into 4ohms would deliver approx. a 16 “dB difference”. This is about 4db lower than what I would require for “peace of mind”. So I guess, instead of getting 105dB peaks at my listening position, this would give me closer to 101dB peaks, without overloading the receiver.

What if I measured the dB at my listening position of one speaker at a volume that closely corresponds to the loudest levels I typically listen at? For example, when I watch a movie, I typically have my receiver’s master volume set somewhere around -15 (sometimes a little lower, sometimes a little higher, depending on the movie).

If I measured this in the right way (e.g. full band pink noise? Actual program material?) and the measurements came in much lower than 101dB, then would that mean I probably don’t need to spend $2,000 on a more powerful amplifier?

Am I on the right track here, or am I way off base?
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post #3742 of 4475 Old 07-16-2019, 09:55 AM
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Unfortunately I can not, as I am carpeted here.
So was Fraunhofer. They tested carpet vs absorber. If you want to test bare floor, try placing pieces of cardboard or wood or anything reflecting at the floor reflection points.

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post #3743 of 4475 Old 07-16-2019, 10:21 AM
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Originally Posted by Soulburner View Post
I feel diminishing returns kicking in with these speakers. I am content with my carefully placed, summed and equalized subs, doing a far better job in the bass department. Therefore, I would be content with a stand-mount from higher up the line than I would trying to get bass out of a floorstander. The only exception is trying to avoid the floor bounce cancellation that can be an issue with woofers high off the floor. With that in mind, I have no doubt the F36 is a well-rounded speaker.
Yeah, definitely diminishing returns. I'd say that the lower end speakers are engineered so well by Revel that you'd need to be pretty OCD about getting the most perfect sounding speaker to want to spend that much more money for something that only brings subtle improvements. In general, I'm a firm believer in strongly diminishing returns in audioland above a certain price point. For speakers that's probably $2k-$3k for floorstanders, $1k-$1.5k for receivers or separate pre-pro + amp, $50 for cables (provided that for each of these categories you get something that measures well).
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post #3744 of 4475 Old 07-16-2019, 10:23 AM
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Seriously? Yes, there is one in Omaha. I will have to check that out!
I went to NFM in The Colony, TX, which is a suburb of DFW. Hope the Omaha store has the same or similar.

I did not initially know about these dedicated listening rooms, since they are a short distance down from the main speaker area. I only recently learned this.

Good luck.
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post #3745 of 4475 Old 07-16-2019, 10:46 AM
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Originally Posted by buckchester View Post
Thank you for your response. The problem is, if I want to have “peace of mind”, so to speak, it will cost me about $2,000. No small price to pay for something that may or may not make a difference.

I was wondering if I could employ a different method to help determine my needs.

My current receiver outputs 100 watts per channel (full band 20hz-20khz, two channels driven). Based on the chart, 100 watts into 4ohms would deliver approx. a 16 “dB difference”. This is about 4db lower than what I would require for “peace of mind”. So I guess, instead of getting 105dB peaks at my listening position, this would give me closer to 101dB peaks, without overloading the receiver.

What if I measured the dB at my listening position of one speaker at a volume that closely corresponds to the loudest levels I typically listen at? For example, when I watch a movie, I typically have my receiver’s master volume set somewhere around -15 (sometimes a little lower, sometimes a little higher, depending on the movie).

If I measured this in the right way (e.g. full band pink noise? Actual program material?) and the measurements came in much lower than 101dB, then would that mean I probably don’t need to spend $2,000 on a more powerful amplifier?

Am I on the right track here, or am I way off base?
Those are 105 dB peaks from each speaker. Add the channels up and things are truly very, very loud. Dangerous to your hearing. If you listen at -15 volume setting in a calibrated system you are in good company, and your amps are loafing. Remember a 10 dB reduction in sound level reduces power demands by a factor of 10.

It sounds as though 100 watts is fine, but be sure that your receiver is designed to drive 4 ohms loads - not all are. Receiver amps are not aways rated with all channels running, so they may not actually be the same as 100 watt stand-alone power amps. Since you already have the receiver, it costs nothing to experiment. The worst that will happen (one hopes) is that the amps shut down and need to cool and reboot. If the amps die and you have line-level outputs you are still set for external amps, which you have just determined that you need. Just (half) joking . . .
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post #3746 of 4475 Old 07-16-2019, 11:06 AM
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Originally Posted by Soulburner View Post
This is interesting. It makes sense as gravity-bound creatures that we are used to having a floor under our feet. However, I am unsure how this fits in with the (seemingly established) notion that broad horizontal dispersion and somewhat limited vertical was preferred by most listeners. I have previously read that absorption (carpet, rug, etc) on an otherwise hard floor improves sound quality, which corroborates that.
The only claim about limited vertical dispersion that I am aware of came from THX in its early days. There was no real science behind the claim which was a "device" to distinguish THX approved (and licensed, $$$) loudspeakers. The recommended loudspeakers typically used multiple vertical woofers and tweeters, thereby causing terrible off-axis frequency responses at the angles of floor and ceiling bounces. Therefore they avoided specifying such mountainous curves in their specs, instead asking for very small deviations in the 0 to 15 degree range. They used the NRCC facilities to develop this and other THX standards and all early acceptance tests were done in Ottawa by Sean Olive, then a student intern on my staff. Ironically, when I joined Harman, one of my first tasks was to convince THX to approve the first JBL Synthesis loudspeakers which failed the THX test - horns were too well behaved: very little change at small angles and smooth fall-offs at large angles. THX had not considered horns as there would not be a large customer base . They were approved.

Clipped pile carpet on a felt underlay is a decent random-incidence absorber at middle and high frequencies, but low incident angles, as will happen, render this less effective.
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post #3747 of 4475 Old 07-16-2019, 11:08 AM
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Originally Posted by buckchester View Post
Thank you for your response. The problem is, if I want to have “peace of mind”, so to speak, it will cost me about $2,000. No small price to pay for something that may or may not make a difference.

I was wondering if I could employ a different method to help determine my needs.

My current receiver outputs 100 watts per channel (full band 20hz-20khz, two channels driven). Based on the chart, 100 watts into 4ohms would deliver approx. a 16 “dB difference”. This is about 4db lower than what I would require for “peace of mind”. So I guess, instead of getting 105dB peaks at my listening position, this would give me closer to 101dB peaks, without overloading the receiver.

What if I measured the dB at my listening position of one speaker at a volume that closely corresponds to the loudest levels I typically listen at? For example, when I watch a movie, I typically have my receiver’️s master volume set somewhere around -15 (sometimes a little lower, sometimes a little higher, depending on the movie).

If I measured this in the right way (e.g. full band pink noise? Actual program material?) and the measurements came in much lower than 101dB, then would that mean I probably don’️t need to spend $2,000 on a more powerful amplifier?

Am I on the right track here, or am I way off base?
Why not measure your "in-room" sensitivity at the listening position using 2.83 V RMS signal to your speaker and go from there?
Then in your situation what I would've done is to watch a few movies, set a comfortable level (see if there is a difference from one movie to another, etc, but I think they should be more or less the same). Edit: you already know the level you are watching at. Then without changing volume at all look at your calibration level using bandwidth limited SPL measurement.

You will know your reference level this way and then can calculate from there. I'm almost 100% sure that you will find your reference level less than 85 dB unless you have a really huge room and your speakers are really far away.

Here is another interesting paper with recommendations on reference levels:

https://www.atsc.org/wp-content/uplo...o-loudness.pdf
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Last edited by aats; 07-17-2019 at 05:17 AM.
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post #3748 of 4475 Old 07-16-2019, 12:25 PM
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Originally Posted by buckchester View Post
Thank you for your response. The problem is, if I want to have “peace of mind”, so to speak, it will cost me about $2,000. No small price to pay for something that may or may not make a difference.

I was wondering if I could employ a different method to help determine my needs.

My current receiver outputs 100 watts per channel (full band 20hz-20khz, two channels driven). Based on the chart, 100 watts into 4ohms would deliver approx. a 16 “dB difference”. This is about 4db lower than what I would require for “peace of mind”. So I guess, instead of getting 105dB peaks at my listening position, this would give me closer to 101dB peaks, without overloading the receiver.

What if I measured the dB at my listening position of one speaker at a volume that closely corresponds to the loudest levels I typically listen at? For example, when I watch a movie, I typically have my receiver’s master volume set somewhere around -15 (sometimes a little lower, sometimes a little higher, depending on the movie).

If I measured this in the right way (e.g. full band pink noise? Actual program material?) and the measurements came in much lower than 101dB, then would that mean I probably don’t need to spend $2,000 on a more powerful amplifier?

Am I on the right track here, or am I way off base?

It's always good to know your speaker's limits, i.e. how much power can they safely handle? I like to have clip lights on my power amps so I can see if the amp is starting to clip. Headroom is a wonderful thing but can be expensive. I have on occasion found myself wanting more power (I'd like it to be a bit louder but the clip lights are starting to flicker). I learn to live with it not being quite as loud as I would like on some things and realize it's probably for the better to preserve my hearing. I do like it loud, I play guitar, spent most of my life working as a recording and live sound engineer. Loud is exciting but I know my limits in terms of SPL and duration and don't push either.
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post #3749 of 4475 Old 07-16-2019, 03:29 PM
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Originally Posted by Rex Anderson View Post
It's always good to know your speaker's limits, i.e. how much power can they safely handle? I like to have clip lights on my power amps so I can see if the amp is starting to clip. Headroom is a wonderful thing but can be expensive. I have on occasion found myself wanting more power (I'd like it to be a bit louder but the clip lights are starting to flicker). I learn to live with it not being quite as loud as I would like on some things and realize it's probably for the better to preserve my hearing. I do like it loud, I play guitar, spent most of my life working as a recording and live sound engineer. Loud is exciting but I know my limits in terms of SPL and duration and don't push either.
Is clipping a thing anymore for modern receivers? It seems like it would only take a few lines of code to check to see if an input signal + desired volume level would result in output clipping and the receiver could lower the volume. I can understand how clipping might have happened with receivers from 20 years ago, but now... ?
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post #3750 of 4475 Old 07-16-2019, 03:54 PM
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Originally Posted by SouthernCA View Post
I will have to read up a bit more. I don't understand why line in and LFE in have different slopes.
It has to do with the LFE-in having greater bandwidth.

And I'm not saying the exact setting I ended up with this time will be best for everyone. We'll see if I end up with that or the middle slope next time I re-do the system. But I'm fairly certain I won't prefer the shallow slope.
Sorry in advance for the thread-jack.

I have a couple of Rythmik F12G subs. Rythmik's crossover controls are confusing and I had to email Rythmik to get the full explanation.

First, the LFE input bypasses the phase and crossover controls. It is meant to be used with an AVR or pre/pro that handles all the bass management. The slope you're seeing with the LFE input is a fixed 12 dB/octave low pass filter that offers the maximum extension within the design envelope of their servo. The servo requires a band-limited input to be stable.

The phase and crossover controls work with the Line input. The crossover is actually a combination of two cascaded low pass filters. The first LPF is controlled by the switch and the selections are:

50Hz/24 = fixed 50 Hz, 12 dB/octave (not 24!)
AVR/12 = bypass, no filter
80Hz/24 = fixed 80 Hz, 12 dB/octave (not 24!)

The second LPF is variable, controlled by the knob, and its slope is 12 dB/octave. So if you choose AVR/12, you get a single 12 dB/octave variable filter. If you choose either 50Hz/24 or 80Hz/24, you get a combination of a fixed 12 dB/octave filter and a variable 12 dB/octave filter. If you set the knob to the same frequency as the switch, you'll get a combined 24 dB/octave response. If you don't set the knob to the same frequency, then the slope will be 12 dB/octave between the corner frequencies of the two filters and 24 dB/octave above whichever is higher. I have the A370XLR3 plate amp, but I assume the others work similarly. The one page manual they give you doesn't explain this well at all.

Sometimes I wonder why they didn't just give us a single variable 24 dB/octave filter. But it works for me. I use the Rythmiks in a 2ch music-only system with stand mounted speakers that run full range. I have the switch set to 50 Hz and the knob at 70 Hz. Having the 24 dB slope start a little higher works better for me because my left speaker suffers from some mid-bass suckout due to a nearby sliding glass door that seems to be transmissive in that frequency range. Setting 70 Hz on the dial gives me a little more output in the 60-80 Hz range to compensate so the overall response is flatter.
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