DeVore Fidelity Orangutan O/96 loudspeaker Measurements

Sidebar 3: Measurements

I used DRA Labs' MLSSA system and a calibrated DPA 4006 microphone to measure the DeVore Fidelity Orangutan O/96's frequency response in the farfield, and an Earthworks QTC-40 for the nearfield and spatially averaged room responses.

The Orangutan O/96 has a very high specified voltage sensitivity of 96dB/w/m. This is both unusual and means that the speaker will play very loudly with very low-powered amplifiers. My estimate of the DeVore's sensitivity was somewhat lower, at 91dB(B)/2.83V/m, though this is still usefully high. Concerned that I had mischaracterized the sensitivity, I checked my estimate by comparing the SPL produced by the O/96 with that from a BBC LS3/5a at the same drive level. The O/96 was 9dB more sensitive than the LS3/5a, which is within experimental error of the original 91dB figure (B-weighted).

As can be seen in fig.1, the O/96 has an unusually high impedance, conforming to the specified 10 ohms. At the 2.83V level used to calculate the speaker's sensitivity, the O/96 will therefore draw less than 1W from the amplifier, which will have a negative impact on the measurement. The impedance magnitude (solid trace) drops below 8 ohms only in the lower midrange and the mid-treble, reaching respective minimum values of 7.2 and 7.8 ohms. While the electrical phase angle (dotted trace) reaches extreme values in the bass, the magnitude is very high at these frequencies. Overall, the DeVore O/96 is one of the easiest speakers for an amplifier to drive that I have encountered.

Fig.1 DeVore Fidelity Orangutan O/96, electrical impedance (solid) and phase (dashed) (2 ohms/vertical div.).

The traces in fig.1 are disturbed by some discontinuities in the midrange, suggesting the presence of cabinet resonances of some kind. Listening to the cabinet walls with a stethoscope while I played the half-step–spaced toneburst track from my Editor's Choice CD (Stereophile STPH016-2), the side and rear walls were very lively between 130 and 230Hz, and some lower-level modes were audible higher in frequency. Investigating the cabinet's vibrational behavior with a simple plastic-tape accelerometer revealed very strong modes at 148 and 219Hz (fig.2), these coincident with the frequencies of two of the wrinkles in the impedance traces. These modes might have lent the speaker the richness on voices noted by AD.

Fig.2 DeVore Fidelity Orangutan O/96, cumulative spectral-decay plot calculated from output of accelerometer fastened to center of rear panel (MLS driving voltage to speaker, 7.55V; measurement bandwidth, 2kHz).

There were also peaks at these two frequencies in the output of the two ports on the rear panel when measured in the nearfield (fig.3, red trace). Though these are down in level, they do result in discontinuities in the nearfield woofer response (blue trace) and the overall low-frequency response (black trace below 300Hz). Other than that behavior, however, the ports' output peaks sharply in classic manner between 35 and 55Hz, its maximum level coinciding with the minimum-motion notch in the woofer's response at 43Hz, somewhat higher than the "mid 30s" mentioned by AD. (At this frequency, the back pressure from the port resonance holds the woofer cone still.)

Fig.3 DeVore Fidelity Orangutan O/96, anechoic response on HF axis at 50", averaged across 30° horizontal window and corrected for microphone response, with nearfield responses of woofer (blue) and port (red) and their complex sum (black), respectively plotted below 350Hz, 750Hz, 300Hz.

The black trace above 300Hz in fig.3 shows the O/96's farfield response averaged across a 30° horizontal window centered on the tweeter axis. Overall it is relatively flat, with small peaks balanced by small dips in the response. The region covered by the tweeter is very slightly less sensitive than the woofer's range; of more concern is the sharply defined peak just below 2kHz. This coincides with a wrinkle at the same frequency in the impedance graph ; this behavior might be due to a termination problem with the woofer cone and its surround at this frequency. However, this peak coincides with a lack of energy to the speaker's sides (fig.4), and so may well not result in coloration. What appears to be an off-axis "flare" between 3 and 4kHz in this graph is actually due to the on-axis suckout in this region filling in to the speaker's sides. Taking this into account, while the DeVore O/96's horizontal dispersion is narrower than usual above 1kHz, it is actually much better controlled and consistent with frequency than I was expecting from a design using a large woofer and a wide baffle.

Fig.4 DeVore Fidelity Orangutan O/96, lateral response family at 50", normalized to response on HF axis, from back to front: differences in response 90–5° off axis, reference response, differences in response 5–90° off axis.

In the vertical plane (fig.5), the optimal response is obtained just above the tweeter axis. This is sensible, given that the tweeter is just 32" from the floor when the speaker sits on its matching stand.

Fig.5 DeVore Fidelity Orangutan O/96, vertical response family at 50", normalized to response on HF axis, from back to front: differences in response 15–5° above axis, reference response, differences in response 5–10° below axis.

I visited Art Dudley to give a listen to the O/96s in his system and to measure their in-room response before bringing them back to my place for further measurements. I averaged 20 responses taken in a rectangular grid 36" wide by 18" deep, and centered on a position 36" from the floor at AD's listening position. (We have found that 36" is the height of a typical seated listener's ears; AD actually sits a little higher.) The speakers were driven by AD's Shindo Corton Charlemagne amplifiers; the result is the red trace in fig.6. The treble slopes down smoothly, if a little more than I would have liked—I found the balance in Art's room somewhat lacking in top-octave air, though the low frequencies were well extended.

Fig.6 DeVore Fidelity Orangutan O/96, spatially averaged, 1/6-octave response in AD's listening room (red); and of Audio Note AN-E/SPe HE (green).

What is fascinating about the O/96's in-room response is that it is almost identical to that of AD's reference speaker, the Audio Note AN-E/SPe HE (green trace). The Audio Notes were placed in the room corners for this measurement, with a severe toe-in; the DeVores were well away from the wall behind them but fairly close to the sidewalls. As with the Audio Notes, there is a peak between 500Hz and 2kHz, and a lack of energy between 100 and 200Hz. I suspect that, with both speakers, the latter is due to destructive interference between the direct sound from the woofer and the reflections from the walls and floor. In the case of the O/96s, these reflections would be reinforced by the fact that the distances between each woofer and the two closest room boundaries were very similar.

I was aware of the lack of lower-midrange energy when I first started listening to the DeVores in AD's room, though that receded as I continued listening. I suspect that this kind of interference is something we accommodate to. I investigated further when I got home, setting up the O/96s in my own listening room and driving them with the Devialet D-Premier integrated amplifier. The red trace in fig.7 again shows the Devore's spatially averaged response in AD's room; the blue trace shows the O/96's response in my room, measured in identical manner. Because I could place the speakers farther away from the sidewalls in my room, which is wider than AD's, their lack of energy in the lower midrange has filled in nicely. Without the boundary reinforcement in my room, the bass is slightly shelved down, though it still extends down to below 25Hz. Though there is still a bit too much energy in the upper midrange, with the solid-state amplifier the treble is considerably more extended in my room, if with the same smooth characteristic measured in AD's room.

Fig.7 DeVore Fidelity Orangutan O/96, spatially averaged, 1/6-octave response in: AD's listening room (red), JA's listening room (blue).

The O/96's step response (fig.8) indicates that both drive-units are connected in positive acoustic polarity, and the smooth integration of the decay of the tweeter step into the start of the woofer step confirms optimal crossover design. The cumulative spectral-decay plot (fig.9) reveals a generally clean decay in the treble and midrange, but with some low-level hash evident in the low treble and a prominent ridge of resonant energy coincident with the on-axis peak at 1730Hz.

Fig.8 DeVore Fidelity Orangutan O/96, step response on HF axis at 50" (5ms time window, 30kHz bandwidth).

Fig.9 DeVore Fidelity Orangutan O/96, cumulative spectral-decay plot on HF axis at 50" (0.15ms risetime).

After I'd finished measuring them, I spent a day listening to the Orangutan O/96s in my room. Even though I knew about the low-treble resonance and the lively enclosure, these problems were considerably less audible than I was expecting. Only with recordings of solo acoustic piano did they get in the way of the music by producing noticeable coloration, the piano's midrange sounding uneven, with some notes obscured. But with well-recorded rock and classical vocal recordings, the measured problems seemed to step into the background, letting me appreciate the O/96's full-range, evenly balanced sound and superb clarity. It looks as if John DeVore has accepted the inevitability of the problems caused by the O/96's physical concept and had carefully worked around them to produce a well-balanced speaker that is also drop-dead gorgeous.—John Atkinson

Company Info
DeVore Fidelity
Brooklyn Navy Yard, 63 Flushing Ave., Unit 259
Brooklyn, NY 11205
(718) 855-9999
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Comments
bplexico's picture
Thanks for the thoughtful review

Art - I enjoyed reading your review, not least because I am a happy owner of the DeVore O/96s. But beyond any need for validation that I may or may not have made the right choice a year ago, I have learned so much from your writings and along with Michael F, they re-kindled my interest in both analog and putting together a system that would satisfy me emotionally and allow me to really connect with my number one priority, music.

With the aid of a wonderful dealer in my area, who has spent an inordinate amount of time with me, allowing me to listen to a variety of systems, I have been able to acquire at last a truly satisfying setup. Oddly enough that system is composed of Shindo, Garrard, EMT, A23 and DeVore, go figure.

A belated thank you for sharing your passion.

Barr

mrplankton2u's picture
Not a very objective review.

"Well balanced"? "Uncolored"?

To start with, 5 db of difference in sensitivity between published specification and measured response is pretty ridiculous for a pair of standmount 2 way speakers costing $12,000. If you can't produce a product that's a little closer to spec than that for that kind of money, then what else could one expect? 

For starters, one could expect a lousy power response. But to the technically educated, crossing over from a 10 inch woofer to a 1 inch soft dome tweeter was going to be pretty predictable. Interestingly, we're not told in this review or in specifications where the crossover point is. But the mess that is the off axis response betweenn 1.5 and 3khz is a pretty good indication.  This might explain the toe in fussing and limited window of accuracy beset upon the listening position. 

And I haven't gotten around to the pretty cabinet that rings like a cow bell...

 

John DeVore might be a great guy. I've never met him. But the tone of this review has me wondering how different it might have been if the "factory" wasn't down the road from those doing the reviewing and the relationship between reviewer and manufacturer of the product being reviewed was a little more "arm's length" - say, made in Taiwan or merry old England. This review reminds me of the $6000 dollar 60 watt tube amp whose volume control got excessively hot to the touch, yet still managed a "very highly recommended". And surprise, surprise - it's builder too was located in New York. Could this be a trend? Hint to budding niche high end audio entrepeneurs:

LOCATE YOUR BUSINESS IN NEW YORK AND INVITE CERTAIN AUDIO JOURNALISTS OUT FOR A DRINK NOW AND THEN....

John Atkinson's picture
It's a long road

mrplanton2u wrote:
the tone of this review has me wondering how different it might have been if the "factory" wasn't down the road from those doing the reviewing...

To address your comments in reverse order:

Art Dudley lives 220 miles from the DeVore factory, which is indeed real, despite your scare quotes.

Regarding your skepticism about the match between a 1" tweeter and a 10" woofer, I shared your skepticism unitl I auditioned the speaker - see my comments in the "Measurements" section of the review.

John DeVore addressed the matter of the O/96's sensitivity in his Manufacturer's Comment.

John Atkinson

Editor, Stereophile

mrplankton2u's picture
Thanks for your candid response.

However, (are you surprised - I'm sort of the critic in chief around here - someone has to be), John Devore's explanation about the published sensitivity isn't making any sense. True sensitivity isn't defined by electrical power dissipated. It is defined by the acoustic output typically measured at 1 meter at 1khz. In  more comprehensive testing regimes as you have sometimes done - the measured acoustic output is averaged over a span of frequencies to which the average human ear/brain have been found to be sensitive. This means that the output impedance of the device driving the loudspeaker under test is or should be irrelevent. If 2.83V (the widely accepted standard) of drive voltage is measured at the loudspeaker while the tone or sweep is being generated, you will obtain the correct sound pressure output of the device under test. If the source impedance is 50 ohms instead of .05 ohms, it really doesn't matter. When 2.83V is measured across the loudspeaker, you will get the correct specification output albeit with a much higher drive level voltage being necessary at the source to overcome internal losses. This is basic electrical engineering 101 and I would hope by now that Mr. DeVore has passed that technical milestone but his explanation doesn't appear to suggest that.

John Atkinson's picture
Ohm's Law

mrplankton2u wrote:
If 2.83V (the widely accepted standard) of drive voltage is measured at the loudspeaker while the tone or sweep is being generated, you will obtain the correct sound pressure output of the device under test.

Except that with a speaker like this, whose average impedance is greater than 8 ohms, 2.83V will be equivalent to less than 1W. John DeVore specifies his speaker at 1W input power rather than 2.83V input voltage, meaning that my measured sensitivity will be somewhat lower than his O/96's specification. Like you I think of loudspeakers as being voltage-driven devices, which is why I am consistent with using 2.83V as a drive level when measuring sensitivity, but this is a convenience as speakers are actually current-driven.

The source impedance of the amplifier becomes relevant when you are discussing the transfer of power from a source to a receiver, as in the olden days of telecommunication. Power transfer reaches a maximum when source and load impedance are the same.

John Atkinson

Editor, Stereophile

mrplankton2u's picture
Yes, the watt sensitivity rating...

The sensitivity rating should be defined as acoustic power output vs applied voltage drive level. The efficiency rating should be defined as the acoustic power output vs. eletrical power consumed. The two are frequently confused because manufacturers love to use the one that makes their product look better - calling them both the sensitivity rating. Regardless, DeVore's explanation was a useless distraction. Speakers are supposed to be rated based on the actual signals applied - not what type of amplifier is being used. If you know what the current through load,, voltage around the load, and phase between the two is - that's all you need to know. The rest is BS fluff.

As for what this speaker actually measures, my guess given the impedance plot and sound output at 2.83V of drive is that it is a few decibels down from the 96db rating with one watt consumed at 1 meter's distance at 1khz. Still pathetic for a loudspeaker that costs six figures. That's one thing I would expect from an expensive speaker - close adherence to published specifications. Is that too much to ask? I guess so.

John Atkinson's picture
Sorry, no

mrplankton2u wrote:
The sensitivity rating should be defined as acoustic power output vs applied voltage drive level.

Except that it isn't defined that way. It is sound pressure level  - pressure being the acoustic analog of voltage - on a specific axis at a specific distance for a given voltage input. See my discussion of sensitivity vs efficiency at www.stereophile.com/content/measuring-loudspeakers-part-one-page-3.

mrplankton2u wrote:
my guess given the impedance plot and sound output at 2.83V of drive is that it is a few decibels down from the 96db rating with one watt consumed at 1 meter's distance at 1khz. Still pathetic for a loudspeaker that costs six figures.

I disagree, Loudspeakers as sensitive as this DeVore Fidelity and that measure as well are relatively rare - see fig.1 at www.stereophile.com/content/measuring-loudspeakers-part-one-page-4 - and almost always expensive.

John Atkinson

Editor, Stereophile

mrplankton2u's picture
Save your lecture.

I intentionally used the words "acoustic power" and "should" for a reason. But you apparently weren't perceptive enough to notice the intent to draw a distinction. Sensitivity in scientific pursuits typically involves a stimulus and measurement of response to stimulus. Applied force is considered the stimulus and reaction forces are considered the response. The laws of conservation of force and momentum govern.  Efficiency in scientific pursuits typically involves a process undertaken over time that measures total energy input to establish a given process versus the actual amount of energy consumed in the process itself over a specific period of time. There, the laws for conservation of energy govern.

This is why I used the term acoustic power because the important distinctions between the two concepts could be more easily illustrated. Your attempt to correct me actually points up your lack of understanding between these concepts. Sound pressure vs. wattage relates force to power and thus energy in a steady state system. Sound pressure to voltage relates force to force. As for your concern about the propriety of using the term acoustic power - that only points up your lack of familiarity with the subject since acoustic power is readily converted from sound pressure in free space - they are two sides of the same coin. Based on the above background in common scientific methods, the proper definition for sensitivity is applied force or voltage to sensed force or sound pressure. The power consumed (force acting through a distance) versus sound pressure (force) is thus not the appropriate definition for sensitivity - at least where proper sceintific method is concerned. Not everyone who reads the drivel of Stereophile is a novice or was born the day before yesterday. It's about time you recognize that fact and accord potential readers with the respect they deserve.

John Atkinson's picture
Many words, little understanding?

mrplankton2u wrote:
I intentionally used the words "acoustic power" and "should" for a reason. But you apparently weren't perceptive enough to notice the intent to draw a distinction.

It looks as if you didn't read the linked article. I was discussing "efficency," in terms of acoustic power output (in watts) for electrical power input (in watts); and "sensitivity," in terms of a sound pressure level at a specific place in space, conventionally expressed in dB against a  reference level, and input voltage. If you mix these up, as you are doing, wanting to specify sensitivity in output power against input voltage, you are committing what my physics professor used to call a "dimensional error": ie, there is a mismatch between the units on either side of the statement.

mrplankton2u wrote:
As for your concern about the propriety of using the term acoustic power - that only points up your lack of familiarity with the subject since acoustic power is readily converted from sound pressure in free space - they are two sides of the same coin.

Yes they are two sides of the coin but that doesn't mean that they are "readily converted." You seem to be disregarding the fact that a loudspeaker is not an omnidirectional radiator at all frequencies but instead has a directivity that varies with frequency. You can't, therefore, assess a loudspeaker's acoustic output power by looking at what happens at just one point in space.

Look, there are four measurements you can make: input voltage; input power; output sound pressure level at a specific place in space; sound power output. Examining output power against input power gives you the efficiency; examining output spl for input voltage gives you the sensivitivity. Three of these parameters are readily measurable: input voltage and power, and spl. One, output sound power is not. To measure output power, you have to integrate the spl readings over the entire solid angle into which the speaker is radiating, which means making a large number of measurements over the surface of that solid angle in an anechoic chamber. Or you use a true maximally reverberant room, which is rare and expensive.

So if you are truly interested in efficiency, you have a long and complicated task ahead of you. But efficiency is not what anyone apart from you is interested in. The underlying question is: How loud does this speaker play for a given input voltage? And the voltage sensitivity, which is straightforward to measure, gives you an answer to that question.

And you keep referring to the DeVore's problematic dispersion, without grasping the point that what John DeVore appears to have done is to balance the anomalies in the O/96's on-axis response against those in the dispersion, the result being that the power response conforms to one of Floyd Toole's criteria for good sound quality, that it be smooth and gently sloping down with frequency. You get an idea of this from the spatially averaged in-room responses published in this review. Above the region dominated by boundary effects and low-frequency room modes, the DeVore O/96's in-room response is commendably smooth and even and gently slopes down with increasing frequency.

I suggest you actually listen to these speakers before passing further comment on their sound quality.

John Atkinson

Editor, Stereophile

JohnnyR's picture
Ho Ho Ho

"I suggest you actually listen to these speakers before passing further comment on their sound quality."

So much for measurements meaning anything or should I say the "interpretation" of the measurements? If every speaker is just going to be praised left and right and the flaws ignored then lets just STOP with the measurements and pile on the praise!  Glory Hallelujah!!! Gets out ur rekorddds and tube amps and full range 15 inch speaker in a huge box and let ur ears have a blast!!!!!!

Glotz's picture
You haven't heard it..

You have no idea whether it's worth $12k or not.

Lots of offensive, shitty attitudes coming from multiple people who wish they owned their own magazine.

JohnnyR's picture
Oh I Already Know............

......it's not worth $12,000 simply from reading what drivers are in it and the box construction and layout, then the measureed response and panel vibrations. A flawed design from the beginning with very little thought put into the final result other than the price tag. Minimum effort for maximum profit. Plenty of better speakers out there for less money.

Sorry but I don't want my own magazine , I just want some truth in the ones out here already.

MVBC's picture
Here is a European example

Here is a European example with high quality drivers:

http://www.toutlehautparleur.com/enceintes-en-kit-c-153/davis-acoustics-klarence.html

Roughly $2,000 a pair. Have a professional do the enclosure for you and you're done for $3,500 max. $12k for those De Vore is simply outrageous. 

Audio Legend's picture
The magazine DID recommend a flawed product.

You did recommend a flawed product. While I do not appreciate the tone of some of the posters, the facts are pretty clear, and actually this conclusion is drawn from your very own words:

"DeVore has accepted the inevitiblility of the promblems caused by the o/96's physical concept...."

Devore does, but should the buyer for the handsome sum of $12,000? What speaker desinger starts with a flawed concept?????

You go on to say:

"Even though I knew about the low treble resonoance and lively enclosure, these problems were considerably less audible than I was expecting."

You did not say INAUDIBLE, but LESS audible.

It really is stunning. I really don't know how it serve the reader to recommend a clearlyflawed product.

JohnnyR's picture
He He

It really is stunning. I really don't know how it serve the reader to recommend a clearlyflawed product.

It DOESN'T !!!! It's all about "reviewing" a FLAWED product in such a way as to not insult the designer ,yet convey to the reader that "Hey, this isn't so bad after all, so just buy it and try it out"  That the reader could buy a MUCH better speaker for FAR less money goes without saying.

mrplankton2u's picture
Yes, stunning is about right.

Yes it is stunning that a product could be designed that violates fundamental best practice design principles resulting in inferior performance - yet still receives a "recommendation" from the reviewing "authority".

Most novices in the speaker design field (read any DIY speaker website) know that you don't operate a loudspeaker transducer outside its effective frequency operating range if you want a good final result. This is so basic that it truly is stunning to think a professional in the speaker building business would knowingly violate such a principle without any apparent or perceived benefit. Operate a sizeable woofer into the low treble and you have a serious reduction in response off axis. You also run a greater risk of producing cone breakup and distortion that IS audible. Run a tweeter too low in frequency and you wind up with a serious increase in distortion due to over excursion with the possibility of overheating and damage at high sound pressure levels. Additionally, you experience an off axis response flare from the beaming woofer to the wide dispersion tweeter. 

In other words - IT'S ALL WRONG. STUNNINGLY WRONG, until of course the writers of Stereophile step in to tell us that it isn't so bad. So what's next on the horizon Stereophile? Are you going to try to convince your readers that the next beautifully stained and clear coated speaker whose enclosure is made of 1/4" pine plywood walls that ring like a siren isn't such a bad idea as long as you put cotton in your ears when listening? Yes folks, this is stunning but sadly, not that unusual for a lot of audio related trade magazines today.

Art Dudley's picture
You seem fixated on that knob...

Mr. Plankton, if the tone of my review strikes you as overly reverential toward the product's maker, that's your right; I could declare, truthfully, that I don't allow those sorts of things to influence the content of my reviews, but I suspect that nothing could change your mind on that point -- you're obviously having too much fun in the sty you've created for yourself here -- so why bother? I will, however, say that the maker of your favorite knob lives and works a few hours from here (I don't know for sure, as I've never been there, nor has Mr. Gibboni ever "taken me out for a drink"), and that I only get to Brooklyn (a 5-hour drive from my home upstate) about once or twice a year. I'm not sure how you explain my fondness for products whose manufacturers and representatives aren't located in New York State, nor my antipathy for some products made and repped by people with whom I *have* socialized -- but, again, you're free to hold and express whatever point of view suits the personna you wish to maintain in this forum.

BTW, the crossover frequency wasn't in the review because the manufacturer doesn't make it public, and I didn't comment on the discrepency between the published sensitivity spec and JA's measurement findings because I never see the latter until weeks after my reviews are written and submitted. And, although you don't seem to enjoy the experience, I'm grateful that you not only read my work in Stereophile but that you appear to follow it so assiduously! 

mrplankton2u's picture
Which knob?

[Gratuitous flame deleted by John Atkinson]

Mr. Dud, there is no other way to characterize it - you gave a product that was obviously defective a "very highly recommended rating". Whether you believe it was an intentional (by design) defect or not, it was in fact a defect. No audio amplifier intended for home or professional use is or even should be considered properly operational when the volume control becomes too hot to the touch during normal operation. Most "normal" reviewing entitites (if they were gracious) would return the product under such circumstances and allow the manufacturer to correct the defect. Other not so gracious reviewing entities would accurately desribe the product under review as having been defective and not award said product with a "very highly recommended" rating. When it comes to the consuming public, just as a singer/songwriter is often considered only as good as his/her latest or sometimes worst recording (in some industries, if the screwup is bad  enough, you don't get a second chance), when a reviewer blows up his credibility with a stupid review, it's very hard to rebuild it. And that is precisely where I place your professional credibility, sir - in the gutter with all the other exploded rubbish.

 

John Atkinson's picture
Fixated much?

mrplankton2u wrote:
No audio amplifier intended for home or professional use is or even should be considered properly operational when the volume control becomes too hot to the touch during normal operation.

It appears you are fixated on this Rogers amplifier. The volume knob gets hot because the amplifier's design places the four output tubes close to the chassis metalwork, which over time heats up accordingly and passes that heat to the control knobs. Suboptimal design, but not a serious flaw, in my opinion.

And please note that "too hot to touch" is a projection on your part. Art's actual comment was "its volume control became uncomfortably warm to the touch during listening sessions longer than an hour." As a responsible reviewer, he noted that fact, which is how you found out about it, and moved on to the product's sound quality, which was sufficiently good for the Rogers amplifier to be recommended.

And again I must warn you to refrain from making personal comments. I will continue to delete such contents and if you continue, will delete your user account.

John Atkinson

Editor, Stereophile

mrplankton2u's picture
Personal comments?

While we're on the subject of "personal comments", perhaps you could refrain from calling posters here "trolls" or uttering abusive,, inflammatory phrases like "STFU".  And perhaps you could curtail writers like Dudley from talking about the "sty I made for myself". Your double standards are obvious and ridiculous for someone trying to appear so proper,objective, and impartial.

My standards of posting/communication etiquette mirror those of other participants in this particular forum or as some Stereophile writers would say, this "clusterfuck" of a forum..Before you cast stones, take a long hard look in the mirror.

smittyman's picture
I Raised the Volume Control Comment

Actually I was the first one to raise a comment about the volume control.  My point was, and still is, that I don't think the volume control, or any other user control for that matter, on any amplifier should overheat.  The fact that it is a $6K amp that we are talking about makes it even less acceptable.  Please note that I did not resort to hyperbole in my original post on this subject because, as you point out, Art Dudley did not say too hot to touch. 

I think a high priced product should be judged on all facets of its operation, not only the sound.  I seem to recall that Listener ran a couple articles about the importance of basic usability and it also seems to me this amp is right up against that criterion.  You are right that it was responsible reporting to identify the issue but I still don't think an amp that isn't designed well enough to disapate heat away from the controls should get such a 'warm' recommendation. 

John Atkinson's picture
Clarification

smittyman wrote:
Actually I was the first one to raise a comment about the volume control.

Understood. I was referring to the fact that mrplankton2u took your ball and has now run with it in multiple threads.

smittyman wrote:
I don't think the volume control, or any other user control for that matter, on any amplifier should overheat.

Just to be clear, the control did not overheat, it simply got hot.

smittyman wrote:
I still don't think an amp that isn't designed well enough to disapate heat away from the controls should get such a 'warm' recommendation.

Okay, but I'd better quit now before the discussion gets too heated. :-)

John Atkinson

Editor, Stereophile

JohnnyR's picture
Speaker Tests are Becoming Less Informative

 The crossover frequency COULD have been determined during the measurements but yeah , you know .....EFFORT.

The tweeter is a run of the mill tweeter nothing special regardless of the words used to fill up the report. A plastic cup glued onto the rear of the magnet is pretty much standard fare.

This design is nothing special. The Dynaco A25 used a 10 inch driver with a large tweeter YEARS ago. I hardly see $12,000 worth of parts or engineering in this thing. An unbraced cabinet and off the shelf drivers no doubt (Edit: I see that he "designed" them himself. Anyone with a checkbook can order custom drivers in large quantities). People can do way better building or buying a Zilch design using waveguides on the tweeter to match the off axis frequency response of the mid-woofer and end up with a MUCH better spaker at a MUCH lower price. Please stop saying it's a high sensitivity speaker. For less $12,000 you can buy  a bigger amp to drive a lesser sensitive speaker and still have money left over. This is just a not well thought out design, other than the seller making a LOT of money for not much thought put into the product.

mrplankton2u's picture
Off axis roller coaster

Atkinson suggests this speaker has a surprising level of balance for a 10 inch woofer crossed to a 1 inch soft dome. The off axis roller coaster response in the crossover region between these two drivers together with the fussy setup and restricted "good imaging" listening area say otherwise. And I agree, if one is going to try to design a two way with a large beaming woofer, a well designed and robust tweeter/waveguide combination are mandatory. Without a waveguide or horn, running a 1" soft dome low enough to pick up a 10 inch woofer is always going to be problematical. And it doesn't matter what tweeter you use - including Scan Speak's best..The spectral decay plot for this speaker also looks lousy - particularly in the (surprise!) crossover region. The contrasts in response curves and decay plot between this and the KEF speaker reviewed below it are night and day.

John Atkinson's picture
Waveguides

Quote:
Without a waveguide or horn, running a 1" soft dome low enough to pick up a 10 inch woofer is always going to be problematical.

If you look at the photos of the DeVore speaker, you can see that the tweeter is indeed acoustically loaded with a short waveguide.

John Atkinson

Editor, Stereophile

mrplankton2u's picture
Yeah, right.

Low frequency gain from that? Surely you jest. 

For a soft dome to reach down into the 1.5 khz range where one would need to cross over to a 10 inch woofer, you'd need a minimum of a 6 inch diameter waveguide. The low frequency gain afforded by the  "waveguide" used by DeVore isn't worth talking about. But the peak off axis and cancellation on axis at 3200hz attributable to this "waveguide" probably is worth talking about. Predictably, you didn't talk about it.

JohnnyR's picture
MrPlankton2U is...........

..............correct. I suggest you get up to date on speaker design by reading more in other forums where people actually build their own and have advanced the art of design way beyond what some manufacturers think is correct.

Regadude's picture
Johnny and Plankton

Hey Johnny and Plankton, how many speakers have you guys designed and sold? You two sound like the guy who drinks 6 beers watching a football game, and then states he could do better thatn the team's coach...

[Edit by JA} What is your expertise, your accomplishments in speaker design?

JohnnyR's picture
You Seriously.............

......want to go there?  Really?  Last chance. Lets just say I have designed quite a few well regarded speaker systems over the YEARS and I have put in the man hours of study and research REQUIRED to know what I am talking about. Lets see how much info you have supplied when it comes to telling us what is right or wrong with this design so far..........ZERO. Come back when you have something that is on TOPIC. Reading your insults and mindless banter is tiresome. Can you keep up or even suggest anything technical? So far I've seen NOTHING from you.

Regadude's picture
Yes I do

I do want to go there Johnny. You talk a good game, so lets get your credentials. Let's see if the talk and the walk match.

To answer your question: I would never buy these speakers. They are way overpriced. Although I have never heard them, I don't expect they would sound very good; certainly not 12000$ worth. The materials used are very ordinary. A plain rectangular MDF box is ok for a 500$ speaker. One can get real wood veneers in a much sturdier and nicer looking, sculpted cabinet for a lot less money. I don't like the looks of these speakers either. 

Having said that, I would not disparage someone for buying them. It's a free country, and people can spend their money on what pleases them. I would not act rudely towards the designer/seller of the equipment either. I won't get into techno babble with you, because I am not trying to prove to the world that these speakers aren't any good. I have my personal opinion about these speakers. I just don't see the point of repeating it ad nauseum, and trying to convince everyone that my opinion is a sacred thruth that should be shared by everyone else. 

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