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Let's see if we can get @avkv or @Floyd Toole to help us with the questions in the posts above (#13034 and #13038 ).

I'm also curious about max power handling of tweeters and SPL capabilities of Revel speakers.

2) Since company rated sensitivity of F206s is 88 dB SPL/w(2.83V)/m, if F206s can handle 200W(40V) continuous input with no compression, F206s can produce 111 dB SPL at 1 meter = 105 dB SPL at 2 meter in anechoic chamber.

The THX reference level is 105 dB SPL for peaks. I can't imagine listening to music (like a CD with very little dynamic range) at 105 dB SPL for any amount of time.

Transient peaks hitting 105 dB SPL hurt my ears if they have much frequency content above 2 kHz or so. Dr. Toole has discussed hearing damage here, please be careful to protect your hearing listening at high volume!
It is not THX who set the reference sound levels, it was the Society of Motion Picture and Television Engineers - SMPTE - and it is embodied in their standards and the equivalent ISO standard. THX just extended it to home theaters. However, there is a significant perceptual difference between a 500 (or more) seat cinema and a small home theater, where those sound levels are often considered to be uncomfortably high, especially with the recent addition of "loudness wars" in which sound tracks are compressed to take advantage of the additional useable dynamic range that digital offers. It is not a technical issue, it is often the judgment of the director who from the back of the mix room shouts "louder" "louder". :(. There are cinemas that compete to be the loudest in the neighborhood. A current problem is that cinema audiences are complaining, walking out, which has caused the movie industry to revisit the situation. Cinemas sensitive to business, have been known to reduce playback sound levels by as much as 10 dB!. An additional problem is blown drivers in cinemas not designed for sustained high sound levels. Of course, film mix engineers are exposed to imprudent sound levels for hours at a time - hearing loss is an occupational hazard. There is work to be done.

Rating the power handling capability of loudspeaker systems is an almost impossible task. The real situation depends totally on the spectral and dynamic content of the program being played. Any test resulting in a number is almost certainly based on a steady-state signal attempting to replicate the "average" program listened to by an unknown population. Then, any number generated by conscientious engineers has a chance of being enlarged by an eager marketing dept.
 

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1) I blown a couple of tweeters during listening test in the past
I am serious when I say, I hope you consider using hearing protection if you are blowing tweeters while testing.

I have done a lot of "testing" with SPL meters to see what levels I can achieve with many different speakers and amps, PA systems etc.

Once I get to a loudness level that is uncomfortable for my ears and I want to see how much farther I can go before seeing clip indicators on power amps, I use hearing protection.

I try very hard to not damage drivers or my ears.
 

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All this talk of max power type amp driving speakers, isn’t it better to have more power than specified max for clean driving/no clipping?
My understanding is: that depends on how the amp is rated. Sony was notorious in the 80s and 90s (no idea how they are today) for rating the power output of their lower-end products at distortion and clipping levels that were entirely unacceptable. Yeah, technically this is 100 watts--but it's un-listenable.

If an amplifier is rated properly, you can expect to get the rated power out of it without distortion or clipping. People like to give themselves more headroom because so many amplifiers are rated for far more power than they can actually cleanly drive.
 

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All this talk of max power type amp driving speakers, isn’t it better to have more power than specified max for clean driving/no clipping?
Before inexpensive mega watt power amps were available, the concern was cost/watt. Having more power than you needed or could use was expensive.

I started doing live sound mixing in 1975 and recording in 1976. High power amps were Crown DC 300's and Dynaco 400's.

https://www.stereophile.com/content/crown-dc-300-power-amplifier

https://www.updatemydynaco.com/Stereo400.html

These days, it's not a bad idea to have enough power (maybe more than enough) to have clean headroom. Still, you don't want amps capable of producing thousands of watts driving speakers that can only handle hundreds.

I did FOH mixing with a PA system that had very high wattage power amps. I walked into the system cold and the amps were all maxed out (level controls full up). I tried to do a sound check and could not get good gain structure, i.e run the mixing console optimally, so I had to turn the power amps down. It was a four way system so it took a while to get it tuned and get good gain structure. Levels on all power amps (high, mid, low, subs) had to come down a lot and the crossover levels dialed in better.

In a home system, if you have power amps with way too much power and no level controls, you will have a problem running your preamp volume control at a good level, i.e it will be barely open before it gets too loud. One wrong move and you will blow drivers with too much power and possibly damage your hearing.
 

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Before inexpensive mega watt power amps were available, the concern was cost/watt. Having more power than you needed or could use was expensive.

I started doing live sound mixing in 1975 and recording in 1976. High power amps were Crown DC 300's and Dynaco 400's.

https://www.stereophile.com/content/crown-dc-300-power-amplifier

https://www.updatemydynaco.com/Stereo400.html

These days, it's not a bad idea to have enough power (maybe more than enough) to have clean headroom. Still, you don't want amps capable of producing thousands of watts driving speakers that can only handle hundreds.

I did FOH mixing with a PA system that had very high wattage power amps. I walked into the system cold and the amps were all maxed out (level controls full up). I tried to do a sound check and could not get good gain structure, i.e run the mixing console optimally, so I had to turn the power amps down. It was a four way system so it took a while to get it tuned and get good gain structure. Levels on all power amps (high, mid, low, subs) had to come down a lot and the crossover levels dialed in better.

In a home system, if you have power amps with way too much power and no level controls, you will have a problem running your preamp volume control at a good level, i.e it will be barely open before it gets too loud. One wrong move and you will blow drivers with too much power and possibly damage your hearing.

And Phase 700s (kabooom) and 700Bs (less kabooms)
 

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Thanks for the information Don, if you were looking at one of these 3 channel ATI NC amps (AT523NC or AT543NC) to power Revel F208 or F228BE LCR's would you choose the 200W unbridged amp or the 500W bridged amp, for 90% movie use?
Tough call. I like lower output impedance which would lean toward the 200 W model but power is nice to have on tap if you need it (big if). I have no idea if the F208 or F228Be are as hard to drive as my Salon2's (suspect not).

You could get a rough idea of power needed here: http://myhometheater.homestead.com/splcalculator.html The F08's at 88.5 dB/W/m are a little less sensitive than the F228Be's at 90 dB/W/m but not by much. A pair of F208's near a wall (typical room) and eight feet away will produce ~110 dB with 200 W which is enough for me. If you are further away or like it loud then the larger amp might help.

HTH - Don
 

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Well, finished up what I think will be my last speaker purchase in a while - ordered a Voce2 to go with the 228be’s, courtesy of @SteveH
Congrats--that's gonna be awesome!
 

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Thanks,

I am retired, so I won't be doing this, others can choose to pick up the torch :) My recollection is that several people have done it, including Peter Walker of Quad (RIP) many years ago. A comparison to a straight wire was the test, and discussing this with him years ago, he allowed that the audible differences were not large. From Wikipedia entry Quad Electroacoustics: "Peter Walker was also attributed with the famous hifi quote "the perfect amplifier is a straight wire with gain" --- the implication being that nothing would be added, and nothing taken away from the signal, just a bigger version of the same thing at one end. It was an aim, a goal, a description of the perfect amplifier - nobody, including Mr. Walker, ever said they'd attained that goal, and even if they did, the chances were that they were severely handicapped by their test equipment at the time."

If comparing products, which some have done, there will almost certainly be differences among amplifiers, but the real question is, do they matter - are they audible in program. As with any A vs. B test problems shared by both products will not be seen, so a null does not indicate perfection, just similarity.

(...)

Since you appear to have done these tests, can you describe your tests in more detail, and share your conclusions? This is the scientific method.


Hafler would be another name. But none has used the method that I've just showed you!

I was really hopping you were the one... :)

So, let me make things even easier for you!

For convenience, you can start by testing OP AMPs directly with that very same method (for obvious reasons, you won't be using loudspeakers this time). I hope that everyone has realized that in the schematic shown, the triangle (the amplifier symbol) represents the amplifier to be null tested. The method is that simple!

Now, let me tell you what the Null Test will show you when testing the most commonly used audio Operational Amplifiers (OP AMPs) that one will inevitably find in almost all audio equipments, power amplifiers included... but just before that, allow me to give you some historic context:

In 1964, Fairchild began to push its way into the IC business. Signetics's circuits being the standard in the market, Fairchild decided to copy them. However, it used its superior cash position, marketing power, and manufacturing strength to undercut Signetics by slashing prices and flooding the market. Signetics was struggling to compete, and began losing money again. Corning saw this as proof of poor management, and used its controlling interest to drive out most of the founders and take complete control of the company.

Signetics managed to stabilize and become profitable again, but it never regained its market leadership, which was firmly held by Fairchild. It continued to innovate in the IC technology, and remained a significant force. Around 1971, the Signetics Corporation introduced the 555 timer IC. It was called "The IC Time Machine". It was also the first and only commercial IC timer available at the time. In 1975 it was acquired by Philips, who continued the brand for some years. In the United States, Signetics reached its manufacturing height at around 1980. Later it was fully integrated into Philips Semiconductors (now NXP).

Perhaps the best-known device introduced by Signetics is the 555 timer IC, which is still widely manufactured and used. (...) Other well-known devices include:

NE5532, a widely used audio op amp, now generic and produced by many other manufacturers. According to one 1993 article, NE5532 was "the standard audio op amp to which others are compared".Electronic Musician. Polyphony Publishing Company. 1993. p. 51.
Europe approves aid for Philips' fire-damaged wafer - The European Commission has authorized the transfer of 33 million euro (about $43 million) in state aid to Philips Semiconductors, for use at its facility at Caen, France, where a wafer fab was damaged by fire on 12 Dec. 2003.

We have moved some of the essential products that were made at Caen to other process and some of the processes have been moved to other fabs such as Fishkill (U.S.) and Nijmegen (The Netherlands). So the critical products that were made in Caen are now being made in other fabs.

On Feb. 12, 2004, Philips said in a letter: "After careful assessment, Philips has determined that the damage to its Caen wafer fabrication plant was significant enough that Philips will no longer be capable of the production of many of the semiconductor part types that the Caen facility had been manufacturing. Many of the products that were being produced in the Caen plant are legacy products that utilize older Philips' wafer processes with no internal alternate fabrication capabilities. Philips' supply of these affected products is limited only to remaining product die and finished product inventories not affected by the fire since there is no possibility of further manufacture of these products by Philips."



To make a long story short, one of those products no longer produced by the older Philip's wafer processes was precisely the NE5532. Until this date and to the best of my knowledge, I'm not aware of any other audio OP AMP (in dual configuration - one chip w/ 2 OP AMPs) that has performed as good as the Signetics/Philips NE5532 on the null-test, not even the NE5532 produced by other brands such as Texas Instruments (same schematic, only different wafer process). Although, regardless of the brand which makes it, the NE5532 still beats every other audio OP AMP model tested to this date (too many to name) by that null test method.

So, the BIG question is: can we ear it? Just double blind test it! Meanwhile, ask those producers and pro audio engineers that swear for the NE5532 inside their consoles and mixers, or better still those who have even identified the Signetics/Philips NE5532 advantage over the NE5532 chip from other brands (again, same schematic, only different wafer processes)!

It's up to you... you can test it for yourself, I've just showed you how. Yes, you are retired Dr. Toole, I just hope your open minded character is not, sir!
 

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Dear NullTest,

I'm going to respectfully ask that you take your posts to a more appropriate thread. This one is for Revel speakers, not amplifiers or the type of tech you want to discuss.

The concept here is to not go off topic. Most people on this thread are here to discuss Revel speakers and not much else. We have had a few times where things have gotten off track and folks ask to get back to the main topic of the thread. I'm trying to prevent problems for you since you are new.

Hope this helps, thanks for understanding!
 

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Ok. No more posts on my behalf here, I leave it as it is. However, I think that any audio conversation with Dr. Toole will be also about his work and his work is essentially about loudspeakers, and as such, also about one specific brand and their models - Revel.
 

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Let's see if we can get @avkv or @Floyd Toole to help us with the questions in the posts above (#13034 and #13038 ).

I'm also curious about max power handling of tweeters and SPL capabilities of Revel speakers.

2) Since company rated sensitivity of F206s is 88 dB SPL/w(2.83V)/m, if F206s can handle 200W(40V) continuous input with no compression, F206s can produce 111 dB SPL at 1 meter = 105 dB SPL at 2 meter in anechoic chamber.

Average SPL's of around 96 dB are very loud to me and transient peaks hitting 105 dB SPL hurt my ears if they have much frequency content above 2 kHz or so. Dr. Toole has discussed hearing damage here, please be careful to protect your hearing listening at high volume!

I can't imagine listening to music (like a CD with very little dynamic range) at 105 dB SPL for any amount of time, yet I read recently this is a target for many live sound mixers at concerts. I walked out of a Keith Urban concert. It was way too loud, had poor instrument and spectral balance and you couldn't understand a word he sang.


Many years ago I had to leave a ZZ Top concert when I finally realized half way through the song they were playing Hot Blue and Righteous - it was so loud my folding chair was moving around on the floor like those old miniature football games from the 70s.


Sent from my iPhone using Tapatalk
 
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Ok. No more posts on my behalf here, I leave it as it is. However, I think that any audio conversation with Dr. Toole will be also about his work and his work is essentially about loudspeakers, and as such, also about one specific brand and their models - Revel.
Yes, you can start another thread to badger Dr. Toole to run your test. Or better yet try it yourself and post the results; would be very interesting.
 
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Well, finished up what I think will be my last speaker purchase in a while - ordered a Voce2 to go with the 228be’s, courtesy of @SteveH
The Voice2 is amazing. It is hard to describe but easy to hear what a big honkin' center speaker does for the sound. The thing is, it has ruined all the other lesser centers in the house for me...
 

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The Voice2 is amazing. It is hard to describe but easy to hear what a big honkin' center speaker does for the sound. The thing is, it has ruined all the other lesser centers in the house for me...
I'm seeing an expensive glimpse into my future...

:p
 
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The Voice2 is amazing. It is hard to describe but easy to hear what a big honkin' center speaker does for the sound. The thing is, it has ruined all the other lesser centers in the house for me...
Have to agree. I started with the C30 and since then have had the C52, C208 and Voice2. Replaced the C30 long ago and the C208 more recently. The keepers to my ears are the C52 and Voice2.
 
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