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| LETTERS 4th Quarter, 2006 |
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All of us at Dagogo would like to thank you, our readers, for taking the time to share your thoughts with us.
We value every opportunity to hear from you, so feel free to type away!
We value every opportunity to hear from you, so feel free to type away!
Subject = [Modified] EAD Ovation Plus
Why did EAD go out of business? Do you think that they may re-emerge in the marketplace? I have an EAD DVD 8800
Player, EAD 8800 Theatermaster Preamp/Processor, and an EAD 7300 Power Master Amp, two Eggleston Works
Savoys, and three Eggleston Works Rosa II's--and I absolutely adore the system!
Sam Bruskin
(Response from Constantine Soo)
Dear Mr. Bruskin,
Thank you for your email and your readership. Your system draws my admiration in no less absolution terms, too.
At the time of the review, namely October 2005, EAD operations had already been suspended by its then-HQ, Alpha
Digital for over a year. Today, Alpha Digital no longer operates a website. If I hear about it from any source, I shall
surely inform Dagogo's readers.
Meanwhile, Noble Electronics provides upgrades to many EAD products. Check them out.
Sincerely,
Constantine Soo
Why did EAD go out of business? Do you think that they may re-emerge in the marketplace? I have an EAD DVD 8800
Player, EAD 8800 Theatermaster Preamp/Processor, and an EAD 7300 Power Master Amp, two Eggleston Works
Savoys, and three Eggleston Works Rosa II's--and I absolutely adore the system!
Sam Bruskin
(Response from Constantine Soo)
Dear Mr. Bruskin,
Thank you for your email and your readership. Your system draws my admiration in no less absolution terms, too.
At the time of the review, namely October 2005, EAD operations had already been suspended by its then-HQ, Alpha
Digital for over a year. Today, Alpha Digital no longer operates a website. If I hear about it from any source, I shall
surely inform Dagogo's readers.
Meanwhile, Noble Electronics provides upgrades to many EAD products. Check them out.
Sincerely,
Constantine Soo
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Subject = Accustic Arts
Dear Constantine,
First of all, I'd like to congratulate you on your excellent web site. It has great information, and has always a very
in-depth look in diverse audio components.
Lately, I've become acquainted of the Accustic Arts line of products through dagogo.com, and I'd like to know your
impressions on the Proline-Mk2 standmount loudspeaker, in case you have already auditioned it.
Sincerely,
Joao Bonina
(Response from Constantine Soo)
Dear Mr. Bonina,
Thank you for your email and readership. Thanks also for your very kind words. On Accustic Arts' speakers, I've rallied
Aaudio Imports, the company's U.S. Importer tirelessly, and at this time Aaudio Imports has no plan to bring the
company's speakers to the States yet.
However, please rest assured that I will keep pressing.
Sincerely,
Constantine Soo
Dear Constantine,
First of all, I'd like to congratulate you on your excellent web site. It has great information, and has always a very
in-depth look in diverse audio components.
Lately, I've become acquainted of the Accustic Arts line of products through dagogo.com, and I'd like to know your
impressions on the Proline-Mk2 standmount loudspeaker, in case you have already auditioned it.
Sincerely,
Joao Bonina
(Response from Constantine Soo)
Dear Mr. Bonina,
Thank you for your email and readership. Thanks also for your very kind words. On Accustic Arts' speakers, I've rallied
Aaudio Imports, the company's U.S. Importer tirelessly, and at this time Aaudio Imports has no plan to bring the
company's speakers to the States yet.
However, please rest assured that I will keep pressing.
Sincerely,
Constantine Soo
| __________________________________________________________________ |
Subject = Luminance Audio KST-150
Editor,
I wish to convey my observations concerning the my own experience with Steve Keiser's two designs, the ST-140 and
the KST-150.
In your review, you did not mention upon the sonic attributes and characteristics of the ST-140. I would assume that you
never actually heard the design, is that true? I recently purchased a KST-150 based upon your review. I have the
option of returning the amplifier for a refund in the event I don't like it. After listening to the KST-150 for some 22 days, I
must say I prefer the old ST-140 instead. Here are my listening observations.
The KST-150 is faster. It has better transient response than the ST-140. However, the KST-150 seems thin and cold
and analytic, especially in the midrange where the ST-140 reproduces the fullness and harmonic textures of
instruments in a more vivid and believable manner. Voices on the KST-150 sound somewhat thin, threadbare while on
the ST-140 I can hear into the textures and vocal nuances to a greater degree than with the KST-150. In the bass,the
ST-140 is fuller and just as extended as the KST-150, but lacks the midbass control and damping of the KST-150. In
the bass, I do prefer the KST-150. In the top-end, the KST-150 is airier and more extended as well as more detailed.
Chalk up another area where I prefer the KST-150.
But in the midrange, I just can't seem to warm up to the newer design and it is in the midrange where most of the action
harmonically speaking is going on. In terms of dynamics, the ST-140 has the edge here too,since the presentation is
more forward.My preferred musical genre is classical and the KST-150 sits me waaaay back in the concert hall.
Everything sounds so far away. On the ST-140 I'm about mid-hall which I consider a balanced perspective. In imaging,
the KST-150 is somewhat more open with more detailed outlines of sonic images as well as a greater sense of space.
But when it comes down to identifying an emotive fulfilment to the music, the ST-140 has the advantage. Admittedly, this
is a somewhat vague quality but does indeed define whether or not I buy the KST-150 or don't.
I have decided to return the KST-150. I have spoken to a number of other ST-140 owners who have performed a similar
comparison and we seem to all agree. In his article in this magazine, Keiser alludes to the advantages of high slew rate.
But I would never trade the midrange magic for any gains in performance at the frequency extremes, which seems to
me at least to be the case here.
Lest I forget, Luminance offers a meager one year warranty on the KST-150. I mean really, one year isn't a very long
time. The ST-140 came with a three year warranty. My question to Steve Keiser is why offer such a short warranty
period? In any event, I really enjoy the articles in your publication. I like the writing and the various listening
perspectives of the different editors. I will continue to be an avid reader.
Sincerely Yours,
Bill Corbin
(Response from Constantine Soo)
Dear Mr. Corbin,
Thank you very much for your email and readership. Your opinion is enlightening and informative. Please let us know
what you think of Dagogo's other articles whenever you can. Write soon.
Sincerely,
Constantine Soo
Editor,
I wish to convey my observations concerning the my own experience with Steve Keiser's two designs, the ST-140 and
the KST-150.
In your review, you did not mention upon the sonic attributes and characteristics of the ST-140. I would assume that you
never actually heard the design, is that true? I recently purchased a KST-150 based upon your review. I have the
option of returning the amplifier for a refund in the event I don't like it. After listening to the KST-150 for some 22 days, I
must say I prefer the old ST-140 instead. Here are my listening observations.
The KST-150 is faster. It has better transient response than the ST-140. However, the KST-150 seems thin and cold
and analytic, especially in the midrange where the ST-140 reproduces the fullness and harmonic textures of
instruments in a more vivid and believable manner. Voices on the KST-150 sound somewhat thin, threadbare while on
the ST-140 I can hear into the textures and vocal nuances to a greater degree than with the KST-150. In the bass,the
ST-140 is fuller and just as extended as the KST-150, but lacks the midbass control and damping of the KST-150. In
the bass, I do prefer the KST-150. In the top-end, the KST-150 is airier and more extended as well as more detailed.
Chalk up another area where I prefer the KST-150.
But in the midrange, I just can't seem to warm up to the newer design and it is in the midrange where most of the action
harmonically speaking is going on. In terms of dynamics, the ST-140 has the edge here too,since the presentation is
more forward.My preferred musical genre is classical and the KST-150 sits me waaaay back in the concert hall.
Everything sounds so far away. On the ST-140 I'm about mid-hall which I consider a balanced perspective. In imaging,
the KST-150 is somewhat more open with more detailed outlines of sonic images as well as a greater sense of space.
But when it comes down to identifying an emotive fulfilment to the music, the ST-140 has the advantage. Admittedly, this
is a somewhat vague quality but does indeed define whether or not I buy the KST-150 or don't.
I have decided to return the KST-150. I have spoken to a number of other ST-140 owners who have performed a similar
comparison and we seem to all agree. In his article in this magazine, Keiser alludes to the advantages of high slew rate.
But I would never trade the midrange magic for any gains in performance at the frequency extremes, which seems to
me at least to be the case here.
Lest I forget, Luminance offers a meager one year warranty on the KST-150. I mean really, one year isn't a very long
time. The ST-140 came with a three year warranty. My question to Steve Keiser is why offer such a short warranty
period? In any event, I really enjoy the articles in your publication. I like the writing and the various listening
perspectives of the different editors. I will continue to be an avid reader.
Sincerely Yours,
Bill Corbin
(Response from Constantine Soo)
Dear Mr. Corbin,
Thank you very much for your email and readership. Your opinion is enlightening and informative. Please let us know
what you think of Dagogo's other articles whenever you can. Write soon.
Sincerely,
Constantine Soo
| __________________________________________________________________ |
Subject = From B&K ST-140 to Luminance Audio KST-150
Dear editor; I have read the installments on design from Steve Keiser. Nicely done.
I have an important question for Steve: I have some technical expertise (EE degree and currently working as engineer
for Hewlitt-Packard). I have a sound technology distortion analysis setup, signal generator and oscilloscope. Using
these instruments I have performed a complete set of measurements on the KST-150, and was wanting to ask to see if
it is possible for me to share my results with your readers. I have not been able to verify Luminance's claim for both
bandwidth and slew rate. As an example, Luminance claims a slew rate of 250v/microsecond. I measure about
42v/microsecond.
I would like to ask designer Steve Keiser what specific test parameters he applies when measuring slew rate. The
amplifier certainly sounds fast, as fast as I have yet heard. So from a practical sonic perspective the slew rate spec
seems to make sense, but in engineering terms, something is awry. Also I measured a bandwidth of 60khz, not 600khz
as stated in the literature. I am not a measurement freak, but believe in exactitude when it comes to thses things. I
personally feels it reflects the integrity of the design process, the product and the people behind it. I read with great
interest your articles covering McIntosh. Now there is a company who's specsmanship is flawless and accurate.
Yours,
Donald Pennington
(Response from Steve Keiser)
In regards to measured slew rate, if we consider the amplifier to be a "black box", ie. a complete system with a specific
transfer function under test, then the method of evaluating slew rate and rise time evaluates the component's ability to
transition its output from 10% to 90% of signal amplitude of a square input as measured at the output.
Assuming that this test is totally comprehensive of a given test component's total transfer function response in both time
and frequency domains, then the results you obtained are consistent with this approach. However, I contend that the
amplifier's and related components' sound radically differ with very similar or identical transfer functions.
When I designed the KST-150, I specifically endeavored to design a circuit whose internal parameters, such as
bandwidth and slew rate, would never have to "see" an input spectral bandwidth capable of slewing the output, thus
avoiding time domain error signals emerging from negative feedback configurations and other active devices' unwanted
contributions to the input signal. Thus, if you were to bypass the output inductor filter network, your measurement
technique would yield a dramatically different result. I suggest you try this by connecting a clip lead from one end of the
output inductor to the other and repeating your measurements. I think you will find the slew rate to be 250volts/
microsecond.
In other words, I assume that a passive component, specifically the output inductor, do not contribute significantly to
time domain response errors. This assumption is a design opinion of course, but I invite those interested to further
query into the complex area of feedback control systems response to impulse functions, which tend to support this line
of thinking. In any event, I would welcome your test results following my suggestion.
Steve Keiser
Luminance Audio
Dear editor; I have read the installments on design from Steve Keiser. Nicely done.
I have an important question for Steve: I have some technical expertise (EE degree and currently working as engineer
for Hewlitt-Packard). I have a sound technology distortion analysis setup, signal generator and oscilloscope. Using
these instruments I have performed a complete set of measurements on the KST-150, and was wanting to ask to see if
it is possible for me to share my results with your readers. I have not been able to verify Luminance's claim for both
bandwidth and slew rate. As an example, Luminance claims a slew rate of 250v/microsecond. I measure about
42v/microsecond.
I would like to ask designer Steve Keiser what specific test parameters he applies when measuring slew rate. The
amplifier certainly sounds fast, as fast as I have yet heard. So from a practical sonic perspective the slew rate spec
seems to make sense, but in engineering terms, something is awry. Also I measured a bandwidth of 60khz, not 600khz
as stated in the literature. I am not a measurement freak, but believe in exactitude when it comes to thses things. I
personally feels it reflects the integrity of the design process, the product and the people behind it. I read with great
interest your articles covering McIntosh. Now there is a company who's specsmanship is flawless and accurate.
Yours,
Donald Pennington
(Response from Steve Keiser)
In regards to measured slew rate, if we consider the amplifier to be a "black box", ie. a complete system with a specific
transfer function under test, then the method of evaluating slew rate and rise time evaluates the component's ability to
transition its output from 10% to 90% of signal amplitude of a square input as measured at the output.
Assuming that this test is totally comprehensive of a given test component's total transfer function response in both time
and frequency domains, then the results you obtained are consistent with this approach. However, I contend that the
amplifier's and related components' sound radically differ with very similar or identical transfer functions.
When I designed the KST-150, I specifically endeavored to design a circuit whose internal parameters, such as
bandwidth and slew rate, would never have to "see" an input spectral bandwidth capable of slewing the output, thus
avoiding time domain error signals emerging from negative feedback configurations and other active devices' unwanted
contributions to the input signal. Thus, if you were to bypass the output inductor filter network, your measurement
technique would yield a dramatically different result. I suggest you try this by connecting a clip lead from one end of the
output inductor to the other and repeating your measurements. I think you will find the slew rate to be 250volts/
microsecond.
In other words, I assume that a passive component, specifically the output inductor, do not contribute significantly to
time domain response errors. This assumption is a design opinion of course, but I invite those interested to further
query into the complex area of feedback control systems response to impulse functions, which tend to support this line
of thinking. In any event, I would welcome your test results following my suggestion.
Steve Keiser
Luminance Audio
| __________________________________________________________________ |
Subject = Shindo Cortese F2a tube amplifier
Do You think Cortese F2a with Shindo Monbrison [preamplifier] is better than an Lafon 300 B with Monbrison to drive a
Klipsh La Scala?
Do You think Nordost SPM interconnect and speaker cables are good for Shindo?
Many thanks,
Pasquale Causa
(Response from Jack Roberts)
Dear Mr. Causa,
I'm sorry but I have never heard the Lafon 300B, and while I'm quite familiar with the Khorns, I have never actually
heard a pair of La Scala's. Having admitted these limitations let me share that the Shindo Cortese F2a has better bass
then I have heard from any 300B. It also has an especially pretty top-end. It was only with voices that I found the
magic of my Wavac MD300B to better the Cortese. By the way that was only with the Western Electric tubes. The
Cortese was an easy winner over the mesh plate 300Bs.
I should also mention that while both my Wavac and the Cortese are both rated at 10 watts per channel, the Cortese
sounded much more powerful.
On your question of cables, let me say that it has been a while since I have listen to Nordost SPM. My memory tells me
that it would be a very good match. Of course I found the silver cables from Shindo worked best of all when I was
reviewing the Cortese.
Last I should mention that I have never had the opportunity at my house to have the Monbrison and the Cortese at the
same time. The Cortese review was written with the Shindo Aurieges-L linestage, and the Monbrison review was done
with the Wavac MD 300B. Since I now own the Monbrison, it is in the works for me to do a follow up on the Cortese with
the Monbrison. So please stay tuned.
Jack Roberts
Do You think Cortese F2a with Shindo Monbrison [preamplifier] is better than an Lafon 300 B with Monbrison to drive a
Klipsh La Scala?
Do You think Nordost SPM interconnect and speaker cables are good for Shindo?
Many thanks,
Pasquale Causa
(Response from Jack Roberts)
Dear Mr. Causa,
I'm sorry but I have never heard the Lafon 300B, and while I'm quite familiar with the Khorns, I have never actually
heard a pair of La Scala's. Having admitted these limitations let me share that the Shindo Cortese F2a has better bass
then I have heard from any 300B. It also has an especially pretty top-end. It was only with voices that I found the
magic of my Wavac MD300B to better the Cortese. By the way that was only with the Western Electric tubes. The
Cortese was an easy winner over the mesh plate 300Bs.
I should also mention that while both my Wavac and the Cortese are both rated at 10 watts per channel, the Cortese
sounded much more powerful.
On your question of cables, let me say that it has been a while since I have listen to Nordost SPM. My memory tells me
that it would be a very good match. Of course I found the silver cables from Shindo worked best of all when I was
reviewing the Cortese.
Last I should mention that I have never had the opportunity at my house to have the Monbrison and the Cortese at the
same time. The Cortese review was written with the Shindo Aurieges-L linestage, and the Monbrison review was done
with the Wavac MD 300B. Since I now own the Monbrison, it is in the works for me to do a follow up on the Cortese with
the Monbrison. So please stay tuned.
Jack Roberts
| __________________________________________________________________ |
Subject = Audio Note AN-E SPe HE Review
Currently own the Audio Note E-SPe loudspeaker. I am selling it to get the J-SPe, as I have found, in my room with my
equipment, that the midrange on the "lesser" J is even better than on the larger E. I don't believe it's a function of my
equipment as I have a great single-ended amp, the Wytech Topaz, a matching tube preamp and a VPI table with a Lyra
Helikon and a good CD player in the Reimyo CDP-777. Have you ever heard the J?
Larry
(Response from Chris Redmond)
Dear Larry,
I'm assuming that when you auditioned the J's, you did so with them positioned in exactly the same position as the E's
which are about to be replaced?
Not having heard the J's myself, I can't comment on the midrange as compared to the E's, except to suggest that while
the larger cabinet of the E's apparently gives an extra half octave of bass, the smaller cabinet of the E may well ensure
less cabinet colouration and therefore an even better midrange.
Of course it could also be argued that the extra bass - that's bass quality as well as the extension - of the E should
'flesh out' and improve the midrange, but all the arguments are really irrelevant as you've done the comparison and
have a clear preference in your room with your equipment.
Just be sure in your own head that what you experienced wasn't a case of the J's midrange being more emphasised
due to the removal of that extra half octave, and that you don't start to miss the E's wider dynamic range.
Experiment with different toe in, distance from rear/side wall, etc, before waving goodbye to the E's and if funds allow,
perhaps you could consider upgrading your E's to the next spec up which would improve the midrange without losing
extension?
Best regards,
Chris Redmond
Currently own the Audio Note E-SPe loudspeaker. I am selling it to get the J-SPe, as I have found, in my room with my
equipment, that the midrange on the "lesser" J is even better than on the larger E. I don't believe it's a function of my
equipment as I have a great single-ended amp, the Wytech Topaz, a matching tube preamp and a VPI table with a Lyra
Helikon and a good CD player in the Reimyo CDP-777. Have you ever heard the J?
Larry
(Response from Chris Redmond)
Dear Larry,
I'm assuming that when you auditioned the J's, you did so with them positioned in exactly the same position as the E's
which are about to be replaced?
Not having heard the J's myself, I can't comment on the midrange as compared to the E's, except to suggest that while
the larger cabinet of the E's apparently gives an extra half octave of bass, the smaller cabinet of the E may well ensure
less cabinet colouration and therefore an even better midrange.
Of course it could also be argued that the extra bass - that's bass quality as well as the extension - of the E should
'flesh out' and improve the midrange, but all the arguments are really irrelevant as you've done the comparison and
have a clear preference in your room with your equipment.
Just be sure in your own head that what you experienced wasn't a case of the J's midrange being more emphasised
due to the removal of that extra half octave, and that you don't start to miss the E's wider dynamic range.
Experiment with different toe in, distance from rear/side wall, etc, before waving goodbye to the E's and if funds allow,
perhaps you could consider upgrading your E's to the next spec up which would improve the midrange without losing
extension?
Best regards,
Chris Redmond
Subject = Furutech e-TP 609 & Power Reference III
Editor,
I must congratulate you on another exceptionally well-written and produced issue of Dagogo. I loved it! Your review of
the AC line conditioner was especially enlightening, for soon after reading your review I went out and purchased one. I
must say the improvement was substantial in my system with very similar results to yours.
I use much the same associated equipment -- Luminance Audio KST-150, Quad electrostatics, Reimyo CDP-777.
Everything sounds so much more open and dynamic. I like the fact that your magazine seems to allow small startup
manufacturers an opportunity for coverage. This is good because it allows the reader to check out equipment the major
publications omit. As a result, the reader benefits by being exposed to so much more. I have also noticed you are open
and supportive of horn loudspeaker designs which I also endorse.
Again, keep up the good work!
Bill Corbin
Editor,
I must congratulate you on another exceptionally well-written and produced issue of Dagogo. I loved it! Your review of
the AC line conditioner was especially enlightening, for soon after reading your review I went out and purchased one. I
must say the improvement was substantial in my system with very similar results to yours.
I use much the same associated equipment -- Luminance Audio KST-150, Quad electrostatics, Reimyo CDP-777.
Everything sounds so much more open and dynamic. I like the fact that your magazine seems to allow small startup
manufacturers an opportunity for coverage. This is good because it allows the reader to check out equipment the major
publications omit. As a result, the reader benefits by being exposed to so much more. I have also noticed you are open
and supportive of horn loudspeaker designs which I also endorse.
Again, keep up the good work!
Bill Corbin
| __________________________________________________________________ |