Thoglette, Kindhornman, others,
The rising level of distortion percentage at lower output is not because of heat dissipation or other causes. It is simply the percentage of noise becoming a higher fraction of the signal. For example, at 100 W, the distortion maybe 1%, getting down to 0.1% at 1 W, and then increasing back up to 0.3% at 0.1 W. The proportion of noise is the same at all levels, but as the levels decrease, it becomes a larger percentage. For an amp biased in Class A, the distortion usually rises smoothly with level after getting out of the noise.
This is of course my noob understanding. The 1/3rd power test is only to ensure that it can stay thermally stable over long periods.
The rising level of distortion percentage at lower output is not because of heat dissipation or other causes. It is simply the percentage of noise becoming a higher fraction of the signal. For example, at 100 W, the distortion maybe 1%, getting down to 0.1% at 1 W, and then increasing back up to 0.3% at 0.1 W. The proportion of noise is the same at all levels, but as the levels decrease, it becomes a larger percentage. For an amp biased in Class A, the distortion usually rises smoothly with level after getting out of the noise.
This is of course my noob understanding. The 1/3rd power test is only to ensure that it can stay thermally stable over long periods.
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Hi Lynn,
Thanks.
The AMR CD-777 uses UDA1305AT DAC chip, which is a Multibit DAC, like the TDA1541. So far, that player is the best CD Player or DAC I heard. (I didn't hear the AMR CD-77 and other players, or DACs, which I cannot afford). I wondered if the Monarchy DAC is better than the CD-777. I don't know of anyone in my country who may have it, so I cannot listen to it. There are but few people on whose listening impressions I'd be willing to follow, without hearing myself. So, for the time being, I'd stay with the CDP I have.
I have fairly low efficiency speakers, tough unconventional ones (Brodmann VC-2).
The tube power amps I tried, in pentode mode I didn't like their sound, while in triode mode didn't have enough power for my speakers and for the volume in which I listen to symphonies. However, I do get what you say about the sound quality of DHTs.
The power amp I have right now is the Pass Labs XA 30.5, which isn't a mere 'Class AB transistor amp'.
I wish I'd find speakers of high efficiency, that will sound at least as good as my present ones, which I could afford. (Being retired, I don't have big money to spare).
Thanks Lynn. Does it still sound good when you turn it down, or does it "come alive"when you turn it up? Two common problems that were demonstrated to me almost 30 years ago in Paris. I still don't understand why, either.But it certainly is a common phenomenon.
This phenomenon has perfectly reasonable explanation /if you want to believe it/ in Tooles book.
Its again reflections to blame
. Reflection are good - they enriched sound no doubt about. They change perceived timbre and enhance localization etc. /of course only some good reflexion/There is threshold value in intensity for reflection to work. Too little and it doesnt work /too much and it doesnt work either/ . Try put symphony orchestra in room three time as big as usual and it will sound weird.
You must put certain amout of energy to build up reflection to above threshold level.
Of course different speakers has different interaction with room.
Most speakers, placed in the same location, react similarly in a room - particularly as freq.s descend. With that - the reflection "cause" is rather hollow argument for a speaker "coming alive".
In *acoustics* however, from which the argument is derived - it's a fairly well documented phenomenon. But there it's live sound in a larger venue which is pretty far removed from stereo reproduction on a set of loudspeakers in a small room.
Unfortunately Toole's book does that a LOT ("grabing" from the study of acoustics), but it's understandable given how little quality research there is into such esoteric topics of loudspeaker presentation.
That's what I found in general too when comparing more 'old school' (or the very few modern but 'hi-fi oriented') high efficiency woofers to their 'pro sound' siblings.
The way I rationalize the difference is as follows:
at (very) low levels, the woofer is barely moving at all, and having a highly compliant spider and outer suspension (high Cms) and especially low overall mechanical resistance (low Rms) become critical in allowing the low-level detail to come through unhindered.
Coming to Lynn's example, both the GPA 416 and JBL 2226 are about as efficient at ~ 97dB/W(1m).
However, the GPA woofer has Cms = 0.78 [mm/N] and Rms = 1.3 [N*s/m], while the JBL has Cms = 0.16 [mm/N] and Rms = 4.9 [N*s/m].
Of course, there's a manufacturing reason for these differences. The JBL woofer, with its comparatively 'stiff' suspensions is quite a bit sturdier if driven hard in PA applications.
Unfortunately, the flip side of this is impaired low-level detail retrieval, and fewer and fewer modern high-efficiency woofers seem to be produced with the latter goal in mind.
Interestingly, as far as low-level detail retrieval is concerned, I have found that controlling these two parameters may possibly be even more important than achieving the ultimate in actual efficiency.
For instance, the Fostex FW405N 15" woofer (~94 dB/W(1m)) has Cms = 0.34 [mm/N] and Rms = 2.5 [N*s/m]. Not quite GPA-like, but still much 'better' than the JBL 2226. And guess what? It sounds much more detailed than the latter (in spite of being 3dB less efficient - it has approximately the same moving mass at ~100 g but a 'weaker' magnet: BL^2/Re = 36 [N^2/W] vs. 75 [N^2/W] for the JBL).
In general, I set for myself the following 'rule of thumb': Rms < 3 (approx.).
Marco
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Most speakers, placed in the same location, react similarly in a room - particularly as freq.s descend. With that - the reflection "cause" is rather hollow argument for a speaker "coming alive".
In *acoustics* however, from which the argument is derived - it's a fairly well documented phenomenon. But there it's live sound in a larger venue which is pretty far removed from stereo reproduction on a set of loudspeakers in a small room.
Unfortunately Toole's book does that a LOT ("grabing" from the study of acoustics), but it's understandable given how little quality research there is into such esoteric topics of loudspeaker presentation.
As soon as you are not in anechoic chamber you are dealing with acoustic
In stereo reproduction case you can add little bit of cognitive science
But serious. I dont know ANY speaker which can play silent as good as at its optimum level.
And about real acoustic event. Tell me which one play really silent? Musical instrument are designed to play LOUD. Because at the time they was invent there was no amplification. This was also supported be designing auditorium rooms to have right amount of reflection to energize rooms. In fact they want to play louder and for more people they use more instruments/players. - this was main drive behind orchestras. In cognitive sense to some extent louder /and with reflections is better/ - this has nothing to do with acoustic.
So do we have any reasonable proof that one speaker can play better silent than another? At which condition - at your home with right cognitive condition glass of good wine, candle glow - low background noise - or at showroom or exhibition - where evil hiend speakers are revieved how they can play silent? And no offense - im really just asking
Very interesting insight.
It will be fun to look at drivers with similar characteristics.
marco_gea,
Yes the T/S parameters are very different between a hifi speaker and one intended to be used for PA sound production. The PA speaker has a very different job to do than our beloved HiFi speakers and fs will typically be very different between the two types of drivers. What you are looking for in a PA driver is just so different than what someone is trying to recreate in their home sound system. High power handling and SPL level are the purview of the Pro Audio type speaker and working in smaller enclosures with multiples ganged together is what is looked for. At the same time for live applications extreme low frequency response isn't even desired, it will create nothing but problems for the sound engineer if the PA is producing 20hz low frequency as that is going to end up in a feedback loop back to the microphones. A typical feature on any mixing console at a live event is going to have a cut switch that will have a roll-off point of 60hz approximately just for this problem and will be used in most closed rooms and even in many outdoor applications. So the response curve that is desired is very different than what we can have with a simple playback system. I think this is what drives the major differences between the two types of speaker design, the use in either production of a live event or the reproduction of that event. One device is not better than the other, they do have a different job to do.
Yes the T/S parameters are very different between a hifi speaker and one intended to be used for PA sound production. The PA speaker has a very different job to do than our beloved HiFi speakers and fs will typically be very different between the two types of drivers. What you are looking for in a PA driver is just so different than what someone is trying to recreate in their home sound system. High power handling and SPL level are the purview of the Pro Audio type speaker and working in smaller enclosures with multiples ganged together is what is looked for. At the same time for live applications extreme low frequency response isn't even desired, it will create nothing but problems for the sound engineer if the PA is producing 20hz low frequency as that is going to end up in a feedback loop back to the microphones. A typical feature on any mixing console at a live event is going to have a cut switch that will have a roll-off point of 60hz approximately just for this problem and will be used in most closed rooms and even in many outdoor applications. So the response curve that is desired is very different than what we can have with a simple playback system. I think this is what drives the major differences between the two types of speaker design, the use in either production of a live event or the reproduction of that event. One device is not better than the other, they do have a different job to do.
Lynn mentioned Great Plains Audio. They're practically neighbors of mine, just down the road in Oklahoma City.
Here's their setup at GPAF/LSAF a few years back:
Sorry for the off-topic post, but I thought their collection of Altec-Lansing restoration drivers and horns was interesting.
Here's their setup at GPAF/LSAF a few years back:
Sorry for the off-topic post, but I thought their collection of Altec-Lansing restoration drivers and horns was interesting.
A 416 version of your 3 pi might be pretty great
I've never been a fan of the McIntosh amps I've heard (or all McIntosh systems). To me they're the equivalent of a V8 muscle car. Not much subtlety. And miss that important aspect you mentioned earlier, they don't sound great at low volume.
Where do you think the properties of the 45 SET come from with the Karna? By your accounts the 2nd and 3rd harmonic are very low.
Given the higher efficiency of your new speakers do you think SET amps with enough headroom (ie all DHT, parts expenses not spared) that are very linear with the first few watts will be just as suited?
Since you said you like electronic music I recommend the new Daft Punk album. Very funky and the recording/mixing quality is fantastic. Mastered a bit too loud, but still sounds nice
The entire album is available to stream on Youtube, Spotify.
jpak,
As far as the Mac amps are concerned there are so many different ways that they did things that it is hard to say they all sound the same. They do have a big following for select models though I really don't want to bother with tube rolling or having to set bias currents and such. I will say that the build quality was something that you couldn't complain about, but I am just not a fan of most tube equipment, especially low powered tubes driving dynamic speakers. I know there are some high powered tube pp amplifiers but that is either very old designs or extremely high priced new equipment. If I was running an all horn loaded system in a house perhaps I would think differently but with direct radiators for the bottom end I want some high powered amps to drive those. I do though still have an old Mac tube tuner that just kills most modern solid state tuners if you want to listen to radio, don't ask me why but it just has better channel separation than I see on most solid state tuners. Picks up stations that a newer tuner will not even seem to see.
As far as the Mac amps are concerned there are so many different ways that they did things that it is hard to say they all sound the same. They do have a big following for select models though I really don't want to bother with tube rolling or having to set bias currents and such. I will say that the build quality was something that you couldn't complain about, but I am just not a fan of most tube equipment, especially low powered tubes driving dynamic speakers. I know there are some high powered tube pp amplifiers but that is either very old designs or extremely high priced new equipment. If I was running an all horn loaded system in a house perhaps I would think differently but with direct radiators for the bottom end I want some high powered amps to drive those. I do though still have an old Mac tube tuner that just kills most modern solid state tuners if you want to listen to radio, don't ask me why but it just has better channel separation than I see on most solid state tuners. Picks up stations that a newer tuner will not even seem to see.
Beyma SM115/N has fs = 29 Hz according to specs. Not bad for a PA driver
Fs per se does not mean much, it's Fs/Qt that determines the low frequency capability of a woofer.
The Beyma still pulls off a very respectable 93.5, though, unlike the typical Pro woofers that usually have Fs/Qt upwards of 120.
I agree this Beyma woofer might be worth listening to!
Marco
As soon as you are not in anechoic chamber you are dealing with acoustic
In stereo reproduction case you can add little bit of cognitive science
But serious. I dont know ANY speaker which can play silent as good as at its optimum level.
And about real acoustic event. Tell me which one play really silent? Musical instrument are designed to play LOUD. Because at the time they was invent there was no amplification. This was also supported be designing auditorium rooms to have right amount of reflection to energize rooms. In fact they want to play louder and for more people they use more instruments/players. - this was main drive behind orchestras. In cognitive sense to some extent louder /and with reflections is better/ - this has nothing to do with acoustic.
So do we have any reasonable proof that one speaker can play better silent than another? At which condition - at your home with right cognitive condition glass of good wine, candle glow - low background noise - or at showroom or exhibition - where evil hiend speakers are revieved how they can play silent? And no offense - im really just asking
True, but the field of acoustics (or its primary study) isn't particularly concerned with a small room condition. (..there is research there, but for the most part it's been in an effort differentiate small and extremely large room interaction vs. that of performance spaces. Continuing study seems focused on performance spaces.)
With reflections in a small room the net result is *louder*, but loudness per se is only a point of comparison that we are used to commenting on (because it's familiar). i.e. "coming alive" at a certain spl. That certain "spl" is arbitrary. It might be more accurate to say that the speaker "comes alive" at a certain input level.
One of the better examples I can think with respect to low input level and a speaker "coming alive" is from a Lowther. (..and it's not a consequence of that hideous peak in the lower treble - which can be eq.ed-out.)
While not "silent" in operation, a Lowther in a backloaded horn provides a good example of a loudspeaker that "comes alive" at lower spl.s. (..of course it also sounds like
when its whizzer starts behaving chaotically at higher spl.s)Relative to even similar designs (whizzer full-range drivers loaded in substantially similar back-horns), that added efficiency of the Lowther vs. competing less efficient full-range drivers seems to make a difference.
By the way, IMO a speaker "coming alive" at lower spl's and describing a loudspeaker as more "dynamic" are in large measure synonyms for the same condition. Certainly there may be specific points of divergence for each descriptor, but for the most part they appear to me to be very similar.
Yes they do! I was very surprised the first time I head a big Bosendorfer concert grand. The little Bosendorfers and many other pianos don't have that beautiful bell-like tone. Some other big grands do a bit, but not to the surprising extent of the Big B.
Agree that it rarely ever comes across in a recording.
Very similar thoughts as well.. The suspension, and particularly the surround which effects extremely low excursion, makes a very large difference.
I think there is a lot more to a driver than this for the "coming alive" aspect - but all else equal it seem to be very important.
BTW, you can destroy the positive effects of this characteristic with enough damping material near the driver in a typical enclosure.
Of course the "flip-side" to an unusually low mass high compliance surround with low edge damping of the diaphram is chaotic break-up that can extend down even into the passband of the driver that would normally be considered pistonic. It tends to show-up in the impedance trace as well. Eh, "no free lunch".
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The loudspeakers I have were produced by Bosendorfer. When Bosendorfer was purchased by another company, the loudspeakers production moved to Brodmann, with, allegedly, the very same sound quality. I heard loudspeakers that were produced by Bosendorfer and I couldn't tell the difference in sound between them and those produced by Brodmann – though I heard them in different rooms, different electronics and different acoustic conditions.
Sorry I should have specified, it's MC30 and MC275 I've heard most frequently in a familiar system. But I couldn't tell you which MK incarnation.