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Old 15th February 2010, 11:11 PM   #51
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Originally Posted by AKSA View Post

The new Soraya is quite an amp, but I need to make wages so it's not cheap.
Hi Hugh,

I hope you don't mind me getting this thread back on track, I'd be interested in any updates you may have with regards to the "New Soraya".

Also, as you've obviously had more listening experience with the LF100, the Old Soraya and the New Soraya, what loudspeakers did you find matched particularly well with your amps (- besides VSonics )?

Needless to say, anyone "out there" with listening experience, I'd be very grateful!

Any new loudspeaker designs on the horizon?

Groetjes, Hugh!
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Old 16th February 2010, 12:26 AM   #52
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Originally Posted by Francec View Post
Not as such, however, you said it yourself; liking the sound of a valve amp doesn't mean that it is objectively better, only that you like the sound. As soon as claims of superiority are made, the discussion moves from personal preference to objective evaluation. Most people are not prepared to admit that their senses are (extremely) fallible and that they engage in self-deception; it is, afterall, a prevailing human trait.
Science has given us what we now have and it is disengenuous of people to claim their senses are superior to the methods of evaluation that are available.

Frank
Trouble is you're taking an extreme objectivist view which isn't entirely justified either is it? We have to be objective and subjective. The fallibility lies not only with our senses but with measurements too and moreover how we relate the former to the latter.
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Old 16th February 2010, 12:26 AM   #53
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Needless to say, anyone "out there" with listening experience, I'd be very grateful!
Ron,
I never owned the original LF100 but had listened to Hugh’s demonstrator for some time in my system prior to buying the LF100 Mk2 that morphed name-wise into the original Soraya, added Platinum input caps and then ultimately upgraded to the Soraya 09. So I can have a go at answering your question.

I have Vandersteen 3ASigs (no sub) and find they work beautifully with the amp. Not really difficult to drive but certainly not the most efficient speakers around. They are nominally 6 Ohm though go down to 4 and the Soraya drives the load with absolute ease. It somehow just seems to have more power than it’s rated at.

Through the evolution of the amp, the fundamentals have not changed much and the LF100 remains a fine amp IMO. I think the improvements sum up as small progressive refinements in distortion reduction giving increased clarity, detail and drive. Attack and decay are impeccable as are layering and soundstage. This gives the Soraya 09 even more accuracy and a noticeable 'presence'. There is also a small increase in base extension that has made it very punchy and natural down low. So in summary; probably only a few percentage points improvement overall but quite noticeable IMO and I'm wrapt.
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Old 16th February 2010, 08:13 AM   #54
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Lyn, thanks for the headz up, appreciated.

Ron,

The chief difference between LF100 Mk II (the first Soraya module, in fact, the one you have) and the latest Soraya module is in bass and low midrange. I can explain this in technical terms from an analysis of the input stage, which is very different to conventional amps, including the LF series. There is thus more impact and slam at a visceral level, and a more vivid presentation generally, whatever the heck that means..... (words are so inadequate). The qualities of clarity, resolution and imaging are much the same, and you would have to describe these differences as musical.

There is no difference in FR; they spec almost identically. Distortion at +20dBU (13.1 watts into 8R) is -84dB H2, and -86dB H3, as follows at 1KHz into 8R//2nF:

Harmonic Frequency Fourier Normalized Phase Normalized
Number [Hz] Component Component [degree] Phase [deg]
1 1.000e+03 1.328e+01 1.000e+00 0.04° 0.00°
2 2.000e+03 8.705e-04 6.553e-05 -88.13° -88.17°
3 3.000e+03 6.572e-04 4.948e-05 -174.31° -174.35°
4 4.000e+03 2.292e-04 1.725e-05 94.00° 93.96°
5 5.000e+03 5.230e-04 3.937e-05 -174.13° -174.17°
6 6.000e+03 1.165e-04 8.774e-06 97.54° 97.50°
7 7.000e+03 9.602e-05 7.229e-06 -165.27° -165.31°
8 8.000e+03 7.260e-05 5.465e-06 102.11° 102.07°
9 9.000e+03 6.501e-05 4.894e-06 -5.15° -5.19°

Total Harmonic Distortion: 0.009367%

These are simulated with good models in LTSpice, and they sound very close, you never hear anything vaguely resembling grainy sound or broken detail.

All Aspen amps, including the original AKSAs, are stable into electrostatic (cf. highly capacitive) loads, and very carefully compensated with silver mica caps.

Hope this helps, a bit more objective, based on specs!

Hugh
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Old 16th February 2010, 12:11 PM   #55
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can we be told what these figures are and briefly describe Harmonic Frequency Fourier Normalized Phase Normalized? I have no notion what these terms mean, they are a bit cryptic.
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Old 16th February 2010, 08:28 PM   #56
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Default SPICE simulations

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Originally Posted by Professor smith View Post
can we be told what these figures are and briefly describe Harmonic Frequency Fourier Normalized Phase Normalized? I have no notion what these terms mean, they are a bit cryptic.
Good Day Professor,

I've started typing a brief explanation several times, only to add more and more information. Basically what Hugh posted is a SPICE simulation. This simulation is based on the fact that a square wave is an infinite series of sin waves. Each line in Hugh's post represents a different measurement and the subsequent results. The 6 separate columns headings are:

-Harmonic Number
-Frequency (Hz)
-Fourier Component
-Normalized Component
-Phase (deg)
-Normalized Phase (deg)

An explanation of how this simulation works, what it means, and how one gets to, for example, total harmonic distortion (THD) can be found in the below link. It explains it better than I can, brief or less brief. It's interesting reading. The deciphering of the column headings above will ease further "googling".

Introduction : MIXED-FREQUENCY AC SIGNALS

Google Books contains "SPICE for power electronics and electric power By M. H. Rashid", which is much more indepth.

I hope this helps.

Ron
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Old 16th February 2010, 08:46 PM   #57
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Default Latest.. Greatest... Soraya

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Originally Posted by LPM View Post
Ron,
I never owned the original LF100 but had listened to Hugh’s demonstrator for some time in my system prior to buying the LF100 Mk2 that morphed name-wise into the original Soraya, added Platinum input caps and then ultimately upgraded to the Soraya 09. So I can have a go at answering your question.

I have Vandersteen 3ASigs (no sub) and find they work beautifully with the amp. Not really difficult to drive but certainly not the most efficient speakers around. They are nominally 6 Ohm though go down to 4 and the Soraya drives the load with absolute ease. It somehow just seems to have more power than it’s rated at.

Through the evolution of the amp, the fundamentals have not changed much and the LF100 remains a fine amp IMO. I think the improvements sum up as small progressive refinements in distortion reduction giving increased clarity, detail and drive. Attack and decay are impeccable as are layering and soundstage. This gives the Soraya 09 even more accuracy and a noticeable 'presence'. There is also a small increase in base extension that has made it very punchy and natural down low. So in summary; probably only a few percentage points improvement overall but quite noticeable IMO and I'm wrapt.

Hi Lyn and Hugh!

Great information from you both, thank you! I have a difficult time explaining how something sounds, the words "presence" and "layers" describe my experience with LF100MK2 best I believe.

As for stability, I found late last year that I inadvertently connected a "non-impedance corrected" ESL panel to my amp. This panel approaches 1 ohm at high frequencies. It played happily for some time, at significant levels... that's not a guarantee kids... don't try this at home. It does prove a point though.

That said; both your listening experience as well as measurements give cause for deliberation. Maybe I should put myself in the market for the latest and greatest Soraya... I'll place the ball firmly in Hugh's court.

Groetjes,
Ron
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Old 16th February 2010, 08:59 PM   #58
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Prof,

Phase is a complex issue in audio amps. We assume that the fundamental, 1KHz in the example given, is the reference, and has 0 degrees phase shift at the output. The normalised phase of the harmonics is the phase shift of that harmonic with respect to the fundamental.

This figure is important, since it changes the timbre of the distortions by augmenting or decreasing the harmonic addition with respect to the fundamental. However, I've never seen it discussed much in audio circles, and I can't give you detail on HOW it affects the sound. But then, the thd doesn't have much correlation with the sound either, so in many ways it is figures for the sake of figures, a failing of the human animal - the 'psychology of numerical appraisal', a phenomenon partly responsible for the mystique surrounding the V12 automobile engine and indeed anything where the numbers are used to convey the grandness of the design - the weight of the Airbus A380 for example. How can something so exquisitely quantified fail to impress?

Ron,

I see you tripping the keyboard fantastic again!! All at sea too, incredible this internet thang...... Hold five on the Soraya, I will contact you later today!

Cheers,

Hugh
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Last edited by AKSA; 16th February 2010 at 09:01 PM.
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Old 16th February 2010, 10:50 PM   #59
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the words "presence" and "layers" describe my experience with LF100MK2 best I believe
Ron, then you will really appreciate the '09' as this is what it does best so by all means talk to Hugh. The extra speed, slam etc or whatever other words one uses in attempting to describe the improvements could be instantly bypassed in a few minutes of actual listening, it just makes incredibly realistic music.
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Old 16th February 2010, 11:25 PM   #60
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Originally Posted by AKSA View Post
Prof,

Phase is a complex issue in audio amps. We assume that the fundamental, 1KHz in the example given, is the reference, and has 0 degrees phase shift at the output. The normalised phase of the harmonics is the phase shift of that harmonic with respect to the fundamental.

This figure is important, since it changes the timbre of the distortions by augmenting or decreasing the harmonic addition with respect to the fundamental. However, I've never seen it discussed much in audio circles, and I can't give you detail on HOW it affects the sound.
Hugh
I'm going to quote from Radical Audio Synthesis This represents one opinion perhaps shared by some and not others as usual with audio.

Quote:
achieving an excellent performing amplifier is not only limited to low THD, IMD or stunning slew rates. But the most crucial element is zero phase or group delay thus retaining the time coherency of the individual components of a complex stimulus.
As in most cases we cant achieve zero normalised phase at every harmonic, perhaps not even close. So it's a question of what the limits of this figure ought to be and on what basis?
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