AVS Forum banner

13021 - 13040 of 18855 Posts

·
Registered
Joined
·
2,352 Posts
Congrats on the new speakers. Really enjoying my F208's as well. What did you think of the shrink wrap?

Sent from my Pixel 2 using Tapatalk
I’m of two minds. My finish was perfect and the shrink wrap may have had a part in helping to insure that.

On the other and it is a PITA to remove and I was cursing it the whole time.
 

·
Registered
Joined
·
1,945 Posts
I’m of two minds. My finish was perfect and the shrink wrap may have had a part inhelpi g insure that.

On the other and it is a PITA to remove and I was cursing it the whole time.
Lol... Right there with you. :)


Sent from my Pixel 2 using Tapatalk
 

·
Member
Joined
·
844 Posts
The apparatus is shown in the attached image, credit to my dear friend Jorge Santos.


In his own words:







Please let me know your findings after test it Dr. Toole :)!
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.

Because we do not hear waveforms (we perceive tiny differences in amplitude response, but not huge differences in phase response) these can show up as differences, but they simply do not matter.

In the end, one must, variable by variable, answer the question "what is the threshold for this variable at which it becomes audible in program?" Over the years many such tests have been performed, some of which are referenced in my book. This is the information necessary for amplifiers (and loudspeakers) to be designed and their performance evaluated. I am confident in the statements I made in my last post - most of the audible differences arise as a consequence of amplifiers being driven close to or above their voltage and current limits. These can be much lower than the "rated" power output (which is measured into a resistive load). Over the years a few amplifiers with oversensitive protection circuits have made their presence known, but otherwise power amplifiers have behaved as neutral devices.

When I was at the NRCC we were contracted by a magazine to compare power amplifiers. This was done using a double-blind setup that allowed the load to be instantly switched, from pure resistance to any of several loudspeakers some of which were selected for their difficult complex impedances. After days of concentrated listening the result was essentially a draw - easily audible differences were attributable to small differences in frequency response. However, one amplifier began to complain at moderate listening levels into one loudspeaker. The manufacturer was notified and a remedy was available in days.

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.
 

·
Registered
Joined
·
317 Posts
I just want to thank John for everything he has done for me and everyone here on the forums. It was big surprise when he asked me to become a part of his team and help folks here on AVS. It all transpired very quickly. I feel honored and privileged to hold this new position.

I hope I can fill John's big shoes here! Don't hesitate to call on me as you would have John. The kind folks at Harman/Revel have offered me their full support so I will make good use of their resources to help answer any questions you may have.

I'm going to the CEDIA show in San Diego next month to meet everyone and get info on all the new products. Of course, I'll give a full report here as soon as I return home.

I'm short on time for the rest of today and tomorrow but will get back asap and carry on!
Hello Rex,
Since John has passed the baton to you, I have a Revel question. I read the following in the ATI NC amplifier manual:

Speaker Connections
Warning: There are two versions of the AT500NC Series amplifier. One is a conventional single-ended ground referenced configuration. These are the AT522NC - AT528NC. The other is a balanced bridge amplifier in which the negative speaker terminal is NOT a ground and cannot be connected to a system ground or to a loudspeaker system with a common ground. The balanced bridge amplifiers are: AT542NC; AT543NC and AT544NC.
Before connecting speakers to any of the AT54XNC models, consult your speaker manufacturer to ensure that any speaker in your system that will be connected to these balanced bridge amplifiers does NOT have internal circuitry with a common ground.


Do any of the Revel speakers have internal circuitry with a common ground?
 

·
Registered
Joined
·
2,468 Posts
Hello Rex,
Since John has passed the baton to you, I have a Revel question. I read the following in the ATI NC amplifier manual:

Speaker Connections
Warning: There are two versions of the AT500NC Series amplifier. One is a conventional single-ended ground referenced configuration. These are the AT522NC - AT528NC. The other is a balanced bridge amplifier in which the negative speaker terminal is NOT a ground and cannot be connected to a system ground or to a loudspeaker system with a common ground. The balanced bridge amplifiers are: AT542NC; AT543NC and AT544NC.
Before connecting speakers to any of the AT54XNC models, consult your speaker manufacturer to ensure that any speaker in your system that will be connected to these balanced bridge amplifiers does NOT have internal circuitry with a common ground.


Do any of the Revel speakers have internal circuitry with a common ground?

OK, you win the first round of "Stump The New Guy"! Gotta say that's some new stuff to me.

As I read it in simplistic terms, balanced vs unbalanced inputs. Speaker system with common ground? Honestly don't know. Sounds like contractor speak for 70V systems? I never dealt with that stuff.

Let me reach out to ATI and Revel to see if I can get an answer to this. It will most likely not be until next week, but you have me curious about this.

Hopefully, an AVS member will chime in and let us know the answer before I can get one.

Thanks for making me look bad on my first day! Just kidding. I'm still learning and not afraid to admit it.
 

·
Registered
Joined
·
12,759 Posts
In the context of bridged amplifiers the negative terminal is actively driven so if the (-) terminal of a speaker was connected to a common ground, like the neutral or safety ground of the power line, you'd be shorting the amplifier's outputs. That often leads to undesirable results. ;) Speakers that do that tend to be those with active electronics such as those with built-in powered woofers. Even those may isolate the speaker input. For passive speakers such as Revel that effectively "float" with respect to ground there is no problem. If you run a wire from amp to speaker and nowhere else you'll be fine. Just do not run a ground wire from something else to the (-) terminal of the speaker (or the amp).

Most passive speakers, i.e. the vast majority of speakers, will work fine with a bridged amplifier. Or the amp companies wouldn't make them.

Do be aware that the effective load seen by a bridged amplifier is halved; an 8-ohm speaker is a 4-ohm load to a bridged amplifier. Most companies derate their amplifiers when bridged to work at twice the single-ended minimum impedance (e.g. an amplifier rated for 2 ohms normally would be rated for 4 ohms when bridged). I don;t recall ATI's specs off-hand.

HTH - Don
 

·
Registered
Joined
·
12,759 Posts
I've been asked by a few folks to add this here; it's my impression of the Revel F208 vs. the Sonus Faber Olympica III. It was originally posted in its own thread; but, it'll find a wider audience of people shopping for Revel here.



So, that leads me to what I'm buying: I'm purchasing the Revel Salon 2. It's a big leap from the $5,000 MSRP to the $22,000 Salon 2; however, I was so blown away by the demo today that I left with the thought, "If that's what these guys can do for $5,000, I can't wait to hear their top effort!"

Besides...if I don't like them @DonH50 will buy them from me! :p
Since I responded in the other thread I'll just summarize here:


  1. Congratulations!!!
  2. I said I'd pay shipping but will certainly take them off your hands... :)

Enjoy! - Don
 
  • Like
Reactions: nalthien

·
Registered
Joined
·
12,759 Posts
p.s. Be careful bi-amping using bridged amplifiers. The internal crossovers may share a common ground, leading to problems, since the two amplifiers' (-) outputs would be shorted. Measure with an ohmmeter to ensure there is no connection between high and low sections when the straps are removed. I would not bi-amp; the crossover is part of the magic.
 

·
Registered
Joined
·
8,499 Posts
thats a lousy avg
 

·
Registered
Joined
·
30,632 Posts
In the context of bridged amplifiers the negative terminal is actively driven so if the (-) terminal of a speaker was connected to a common ground, like the neutral or safety ground of the power line, you'd be shorting the amplifier's outputs. That often leads to undesirable results. ;) Speakers that do that tend to be those with active electronics such as those with built-in powered woofers.
Exactly. This configuration of the ATI amps has been apparent to those of us with a technical bent. They use the same Hypex modules in all of them with the low powered ones using 1 module per channel and the high powered ones using a bridged pair.

This is pretty common among Class-D module-based amps from many many manufacturers and is safe with almost all (all?) passive speakers. Of course, active speakers and active subs are generally not relevant because, for the most part, they are fed by line-level (preamp) outputs, not external power amps. There are exceptions and, I note from other posts, REL specifically proscribes using the ATI bridged amps (and any other such bridged amps) with their subs. (REL has always been a bit odd-ball, imho.)
 

·
Registered
Joined
·
15 Posts
Concerning comparison Between Revel concerta2 F36 vs Performa3 F206 vs F208 and dynamic compression vs power handling capacity.

I have a small HT room/study room (35-40m3). but sometimes I like to enjoy movie at Reference levels.
I have a decent subwoofer to perform at reference level (115 dB SPL) down to 16Hz (in the room, of course).
I am wondering whether F206s can play loud enough at the reference level with no issue of dynamic compression and power handling in my HT/study room.

According to the measurement of F206 at soundstage megazine, F206 seemed to suffer from dynamic compression, especially at lower band of tweeter, already at the level of 90 dB SPL (at 2m).

Since the precedent concerta F12 have excellent dynamic range (although a lot more non-linear distortion than Performa floorstanders), I am wondering that F36 may play louder than F206 with less compression. The recent Butterworth review at hometheaterreview suggested that F36 have better dynamic range (play louder) than F206.

The Spin-o-rama data showed the frequency response of F36 seemed to be not as smooth as that of F206. However, Dr. Toole and Dr. Olive always said, lower price lines generally have the same sound quality, but have limited bandwidth (less bass extention), dynamic range (less loud), and/or more non-linear distortion than higher price lines.

Since I have a decent subwoofer, bass extension is less an issue. I am curious that F36 have the dynamic range of F12 which have excellent dynamic range (obviously play a lot louder than F206).
and I am also curious the non-linear distortion levels of F36. Although F12 can play very loud, the non-linear distortion level is not pretty (at least for the eyes).

If the lower impedance at around 3Khz are responsible for compression of F206s, could F208s perhaps have the same problem? Since the tweeter and midrange units seem to be identical between F206s vs F208s.

I read what Kevin Voeks said about Salon2 vs Studio2. Similary, F208s "moves more air and has greater output, particularly in the bass" than F206s. I am wondering how much F208s play louder than F206s in the midrange and the tweeter ranges, and the dynamic capability of F206s.

Are F206s capable of producing 105 dB SPL at 2m in an anechoic chamber (if not, at least in a normal listening room) when tested by frequency sweep signal? (of course excluding
 

·
Registered
Joined
·
317 Posts
In the context of bridged amplifiers the negative terminal is actively driven so if the (-) terminal of a speaker was connected to a common ground, like the neutral or safety ground of the power line, you'd be shorting the amplifier's outputs. That often leads to undesirable results. ;) Speakers that do that tend to be those with active electronics such as those with built-in powered woofers. Even those may isolate the speaker input. For passive speakers such as Revel that effectively "float" with respect to ground there is no problem. If you run a wire from amp to speaker and nowhere else you'll be fine. Just do not run a ground wire from something else to the (-) terminal of the speaker (or the amp).

Most passive speakers, i.e. the vast majority of speakers, will work fine with a bridged amplifier. Or the amp companies wouldn't make them.

Do be aware that the effective load seen by a bridged amplifier is halved; an 8-ohm speaker is a 4-ohm load to a bridged amplifier. Most companies derate their amplifiers when bridged to work at twice the single-ended minimum impedance (e.g. an amplifier rated for 2 ohms normally would be rated for 4 ohms when bridged). I don;t recall ATI's specs off-hand.

HTH - Don
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?
 

·
Registered
Joined
·
317 Posts
Exactly. This configuration of the ATI amps has been apparent to those of us with a technical bent. They use the same Hypex modules in all of them with the low powered ones using 1 module per channel and the high powered ones using a bridged pair.

This is pretty common among Class-D module-based amps from many many manufacturers and is safe with almost all (all?) passive speakers. Of course, active speakers and active subs are generally not relevant because, for the most part, they are fed by line-level (preamp) outputs, not external power amps. There are exceptions and, I note from other posts, REL specifically proscribes using the ATI bridged amps (and any other such bridged amps) with their subs. (REL has always been a bit odd-ball, imho.)
Good information thanks. It was your review that made me curious about ATI NC:
Conclusion: I am completely taken with ATI's AT543nc. It seemed to do everything right, and didn't get in the way while communicating the elements and the spirit of the music.
Read more at https://www.stereophile.com/content...channel-amplifiers-page-2#pm7xPT9PDSveyP4d.99


It seems you really enjoyed that amp.
 

·
Registered
Joined
·
15 Posts
1) Why is this important in your application?

2) Is there a numerical answer that is useful, and is computed by doing some sort of math with these two values?
1) Because THX reference level for movie is 105 dB SPL at listening position (around 2m from front speaker in my listening room). Sometimes I like to watch movies at the reference volume levels.

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.

As measured sensitivity in Soundstage and other audio journals was around 86 dB, Soundstage measurement suggested dynamic compression especially at 2-5kHz, and power handling capacity is unknown for F206s, I am not sure that F206s can produce 105 dB SPL at 2 meter in anechoic chamber.

However, as I recall, some people including John Schuermann in this forum wrote that F206s are capable of reference levels especially with a sub. I like to know how F206s can produce reference volume levels.

I own several Revel speakers. I just want to know exact performance of these speakers.

I blown a couple of tweeters during listening test in the past.
Since service for damaged Revel speaker (such as getting replacement parts) is difficult in my region, I tried not to damage these very-good sounding loudspeakers.
 

·
Member
Joined
·
844 Posts
1) Because THX reference level for movie is 105 dB SPL at listening position (around 2m from front speaker in my listening room). Sometimes I like to watch movies at the reference volume levels.

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.

As measured sensitivity in Soundstage and other audio journals was around 86 dB, Soundstage measurement suggested dynamic compression especially at 2-5kHz, and power handling capacity is unknown for F206s, I am not sure that F206s can produce 105 dB SPL at 2 meter in anechoic chamber.

However, as I recall, some people including John Schuermann in this forum wrote that F206s are capable of reference levels especially with a sub. I like to know how F206s can produce reference volume levels.

I own several Revel speakers. I just want to know exact performance of these speakers.

I blown a couple of tweeters during listening test in the past.
Since service for damaged Revel speaker (such as getting replacement parts) is difficult in my region, I tried not to damage these very-good sounding loudspeakers.
Soundstage uses the measurement system I left behind when I left the NRCC in 1991. It is a good system and the data are accurate, but the power compression test is overly demanding, being a stepped tone which, at those sound levels translated to broadband signals would be extremely loud! So, I would not. be concerned about small amounts of "indicated" power compression, as it is very likely at program sound levels higher than you would tolerate, much less derive pleasure from. As I have said in other forums, I would do it differently now.

The 105 dB reference sound level is the steady-state sound level in a normally reflective room - not an anechoic chamber.

You might want to check out Part 3 of the series of articles on the companion website to my new book - it is open access, not necessary to buy the book. Go t www.routledge.com/cw/toole
 

·
Registered
Joined
·
2,468 Posts
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.
 
13021 - 13040 of 18855 Posts
Top