Sloped baffle

Sounds_real_audio -- your comment re placement if the drivers is interesting. There are some brands that stuff drivers every-which-way into the front baffle. One brand that comes to mind is Nola. I wonder how the Nolas manage the time and phase coherence attribute.

Bombaywalla, ... that;s for the links. I started reading into the threads. This is very complicated stuff. And I thought getting my arms around amp and speaker compatibility was tough. Speaker design is a beast. I will return to these threads over the weekend.

In the end, as it seems to be the case with end end electronic gear, we're talking about design compromises. No perfect solutions ... just trade-offs that hopefully result in a product that sounds good.

Thanks

I recall seeing the terms "time coherent" and "phase coherent." Do these terms mean the same thing or are they different?

Since this thread speaks to speaker alignment, perhaps someone could explain in layman's terms what causes speaker to operate out of phase. Does it have something to do with the use of caps and chokes in the x-over? Or perhaps the attribute of a dynamic speaker creating its own back EMF by reason of the voice coil moving in a magnetic field??

Incidentally, do all these electrical dynamics operating in tandem cause the electrical phase shifting that gives most amps a headache?

Thanks

Bombaywalla ... I read as much of the discussions as I could before falling asleep at 1:30am in the morning. No surprise ... the physical science is way over my head. But I do have some take-a-ways that I would like to share. As a threshold matter, I ask whether we are "polishing a turd" as a practical matter.

As a warm up, there was some discussion which addressed whether using mics to record a musical presentation accurately captured the complex sound wave information that emanated from the multiple performers and instruments. One poster said that all a mic could do was sample a point in 3-D space, thereby missing a considerable amount of sonic/acoustical information. Even using multiple mics, while an improvement, still left much sonic information "on the floor," figuratively speaking.

Next ... the mastering process. So called sound engineers manipulate the sonic information that was imperfectly recorded at the live performance. The result is more sonic contortion and distortion.

Let's skip the next steps relating to the reproduction and transmission of source material via the various media used today (e.g., LP, CD, SACD, internet downloads, etc) and the electronics used to decode the information back into analogue electrical signals that are fed into the speakers. Suffice to say that additional contortions and distortions are infused into the analogue signal before it even reaches the speakers.

Ok, we're now at the speakers and a whole new set of issues present themselves. The bottom line challenge is that our speakers have to reproduce, more like reconstruct, the complex electrical analogue signals back into sound waves that are in phase through the whole harmonic spectrum.

And here the engineering problems and challenges are almost insurmountable: designing a system using multiple drivers that are mounted on a baffle (sloped or not sloped) to reproduce a point complex source sonic wave front that is the same as the original signal, even as modified by the sound engineers at the studio. My take-a-way is that the speaker designer can solve one problem, but create 5 more.

I don't want to embarrass myself by trying to faithfully restate what was said in the various posts. Suffice to say there are physical science challenges presented with every electrical and mechanical component that makes up a complete speaker system. At best ... what reaches our ears is the product of price point driven compromises that are ultimately limited by the laws of physical science.

My bottom line take-a-way is if "it" sounds good, "it" is good. Sure, we can and should audition speakers. Some will sound better than others. But to think any one speaker has perfectly solved all the engineering challenges and is able to faithfully reproduce a point source complex sound wave at the listening point is a pipe dream ... more like shear nonsense.

Perhaps that may be the reason many audiophiles and reviewers say that while specs and stats are informative ... in the end, what counts the most is how a speaker **subjectively** sounds to THAT listener, plugged into THAT listener's rig, positioned in THAT listener's sound room, and so forth.

And to me, that is what makes our hobby fun. Right now, I am listening to Eugene Ormandy, conducting the Philly Orchestra, performing a suite of various Saint-Saens selections. I am still enjoying the music even though it is being imperfectly reproduced by my imperfect rig.

Cheers,

Bruce

Bombaywalla, I have a follow up question. How are small speaker manufacturers able to design speakers without the benefit of the R&D budget, engineers, and testing facilities that some of the larger manufacturers have at their disposal.

For example, I recall reading that Focal, Harman and Paradigm have anechoic testing chambers, staffs of engineers and physical facilities that presumably enables these companies to make rational and informed choices when designing and building speakers. I also recall reading that these companies manufacture in-house their own drivers.

That is a question ... not a statement.

Bruce

Thanks Tim. I'm listening to a HD CD of Dave Brubeck's, "Time Out." Perhaps I'm just used to listening to sonic swill, but the imaging is more than satisfactory and the music is quite enjoyable. My fronts are Paradigm S8s (v3), with beryllium tweeters.

Btw, I think the original recording was made in 1959. Maybe that was the Golden Age of music recording, maybe not. But the HD CD redo sounds great.

As an Fyi, I bought the CD from the Acoustic Sounds web site. AS is located in Kansas. Very good source of music in all formats.

BIF

Psag, I don't think the last couple of comments posted before your comment (mine included) deviated from the OP's question about sloped baffles. I say that because sloped baffled may be used to address (in whole or part) issues relating to using multiple speakers and electronic crossovers.

Bombaywalla and others have provided us with a cornucopia of information about time and phase coherance -- sloped baffles just being a subset of the larger issue. Quite honestly, I didn't realize that the time and phase alignment problem was so difficult to solve.

Having said that, admittedly, I do not fully appreciate to what extent a speaker's sonic performance is compromised by time and/or phase errors. Perhaps, as Sounds_Real_Audio just posted, the issue may be more hype than real. I just don't know.

Al and Ralph .... where are you??? :)

Tim, although I don't understand the science, I recall reading that a sloped baffle is one component of achieving phase coherence. The proper cross-over order (1st, 2nd, and so forth), plus maintaining a specific listening position, plus, setting the cross-over frequencies at the right points, and so on and so forth also contribute to maintaining optimal phase coherence.

In addition, assuming that the drivers are in proper phase alignment in the overlap region of the cross over points, presumably there should not be phase cancellation or augmentation which will mess up the frequency response. That is frequency response should remain flat. But what about maintaining the proper harmonic structure of complex musical passages?

What other benefits are gained by locking one's head in a head vice in order to maintain the precise listening position, which presumably will enable the wave fronts from the various drivers to combine in an optimal phase coherent fashion at the listening position.

So ... how much of this is hype? What other characteristics make for a good sounding speaker? I used to think I had a handle on this this issue ... but no more.

BIF

Al and Ralph ... are you catching any of this?? Throw me a line. I'm sinking in techno quick sand.

Ok ... if Tim or Bombaywalla catch this, here the ultimate Q. How can one tell whether a speaker is time and phase coherent? Critical listening? Reviewer comments? Bench test?

If critical listening is that important, the real challenge for us is, as many have written, that it is not easy to meaningfully audition speakers. So what's a person to do?

I'll ask again, how important is time and phase coherence? FWIW, ... really more as an FYI, ... Paradigm's web site states that its "speakers have phase coherent crossovers designed so that the summed output of the drivers is completely and accurately rejoined." Is that hype? It is true at all frequencies? Dunno

Thanks again.

Al and others, take a look at John Atkinson's step measurements of the Revel Studio 2:

http://www.stereophile.com/content/revel-ultima-studio2-loudspeaker-measurements

JA notes that "the speaker is time-coherent rather than time-coincident: each drive-unit's step smoothly hands over to the next lower in frequency. This correlates with the superb frequency-domain integration between their outputs ...."

Two observations on my part.

First, the Vandy 7's step response plot shoots up like a rocket and then quickly rolls off and stays down. By contrast, the Studio 2 shoots up, rolls off and then rolls back up again. What does this mean? Why the differences?

The other observation is that the Studio 2 has a ruler flat frequency response. I believe the Studio 2 uses high order cross-overs, like my Paradigm S8s.

Interpretive comments are welcome.

Just a supplemental fyi, here JA's bench test measurements for the Revel Salon 2:

http://www.stereophile.com/content/revel-ultima-salon2-loudspeaker-measurements

And one more, the might Magico Q7:

http://www.stereophile.com/content/magico-q5-loudspeaker-measurements

If nothing else, perhaps someone can explain how to properly interpret what these measurements mean. They do not look like the Vandy 7.

Bombaywalla, I'm somewhat familiar with NRC test facility. But I am not sure which of the NRC tests speaks to time and phase coherence.

Btw, I surmise that the reason many of the top speakers, like the Magico Q5, that have flat frequency response plots and probably use higher order cross overs is because the driver timing is tweaked at the cross over points to optimize wave cancellation and augmentation. But ... the drivers are not otherwise in phase outside of the cross over overlap region.

So ... even if the speaker specs well on the bench, it may very well be distorting complex sound patterns as Roy Johnson explains in his articles.

Bombaywalla, did you or Tim mention that one mark of a phase coherent speaker is one which has a flat impedance and phase plot. Take a look at the Magico S5's specs. Is there anything else apparent from the NRC tests that permit inferences about phase coherence?

http://www.soundstage.com/index.php?option=com_content&view=article&id=1043:nrc-measurements-magico-s5-loudspeakers&catid=77:loudspeaker-measurements&Itemid=153

Al, here's another Roy Johnson article I clipped. Perhaps if you get a chance to read his articles, please share comments and thoughts:

http://greenmountainaudio.com/speaker-time-phase-coherence/

Btw Al, you may find the square wave pics in the article to be of interest. It seems that using higher order cross overs creates an almost unsolvable electrical problem.

BIF

Excellent comments gents. I'm hoping Al (Almarg) and Ralph (Atmasphere) get around to reading Roy's articles and sharing their comments.

Although it has been said many times, designers of audio gear take into account many features and do their best to balance, maybe better said ... optimize, what comes out of the metaphorical oven. I'm sure phase coherence is just one of many important factors. That's why I'm hoping Al and Ralph weigh in here to help us better understand the relative significance of phase coherence as compared to other factors.

Bombaywalla, I agree that one shouldn't base expensive purchase decisions solely on reviewer comments. But there's a problem; one that has been touched on by many A'goners including me over the years. There are very few hi-end B&M stores around anymore. And to the extent such stores are around, setting up meaningful and fair auditions is very difficult. Oh ... and as far as Green Mountain is concerned, no dealers near me.

Not sure what else to say. Another potentially huge sleeper problem that is finally getting the press it deserves.

Ng... thanks for the phase coherence article. The article seems to be based on scientific controlled studies and tests. Rather than paraphrase the conclusions, I copied them here:

"So what conclusions regarding the audibility of phase distortion can we draw from the all of the above?

'Given the data provided by the above cited references we can conclude that phase distortion is indeed audible, though generally speaking, only very subtly so and only under certain specific test conditions and perception circumstances.

'The degree of subtly depends upon the nature of the test signal, the dB SPL level at which the signal is perceived, the acoustic environment in which the signal was recorded and/or played back as well as the Q & fo of any filter networks in the signal stream. Certain combinations of conditions can render it utterly inaudible.

'Room acoustics further masks whatever cues that the hearing process may depend upon to detect the presence of phase distortion."

And here's my personal bottom line. Phase coherence is just one of many variables that is taken into account when designing a speaker system ... and there are many. As many folks have said, trust your ears and audition as many speakers as you can. But ... if I was asked to buy speakers based on their phase coherence characteristics as a stand-alone factor, I personally would not.

Thanks again Ng.... Good article. It puts the issue into context.

Bruce

Ngjockey and Bombaywalla ... I find the issue of phase coherence to be intellectually interesting. I also find Roy's article and the article Ng... provided to be equally interesting. If I had the time, if there were more B&M stores around with a variety of speaker types, and if the salepeople were game to burn time to experiment, I'd love to build up a personal anecdotal portfolio of experiences.

To date I have only one data point, which is almost useless. I spent 90 mins about 2 years ago with Vandy Treos. They just didn't do it for me. Imagaging, soundstage and musicality were nonextant.

And if the pushback is that they weren't set up correctly, or wrong cabling, wrong positoning, not leveled, and so forth, my response is .... still not impressed. Even if the Treos would have taken me to the 8th dimension if all the foregoing variables were controlled ... I am still not convinced. I want to flip the switch and listen to music. Not interested in using an oscilliscope to figure out how to enjoy music.

This is a fascinating thread. I hope it will continue to attract more comments from folks who have relevant experiences.

BIF

Bombaywalla, please list the major speaker brands that are time and phase coherent. At this point, I am aware of three brands: Vandersteen, Thiel and GMA. Are there others?

The reason I ask is because I'd like to check area dealers who sell time and phase coherent models and maybe do some comparative auditioning. The other alternative is audio shows.

Thanks

Lewinski... great post. I was impressed by the various digital analyses and corrections that the software was able to effect. Hopefully, speaker manufacturers will be able to achieve greater time and phase alignment, driver linearity and low distortion by designing better X-overs. It may be that the best solution will be an active crossover that can effect the various functionalities that were the subject of your post.

I realize that Richard Vandersteen does this on his high end speakers to some degree, but it sure would be nice if it would be more plug and play. After all, not everybody is a former NASA rocket scientist or a Steven Jobs/Bill Gates computer genius.

Thanks.

@Nrenter ... you make a fair point. My non-techie surmise that the "non-linearity" you described is the reason why manufacturers use multiple drivers. I suspect that in making design trade-offs, the characteristics of the particular driver are chosen to optimize performance within the chosen pass-band.

Sorry to be tooting Paradigm's figurative horn again, but from a non-techie's perspective the drivers used in their Signature line might address some of the nonlinear concerns you mentioned. The tweeter uses an ultra low mass and hard beryllium dome. The motor uses neodymium magnets rated at 20,000 gauss at the voice coil gap .... (btw, is that a lot??). Plus ferro-fluid for cooling and low distortion.

Similarly, the mid driver uses an extremely light and strong cobolt/aluminum cone. The motor uses neodymium magnets rated at 15,000 gauss at the voice coil gap. Plus ferro-fluid for cooling and low distortion.

And that's enough tooting for Paradigm. I don't work for them and they certainly don't pay me.

But another manufacturer who seems to put a lot of thought and effort into their drivers is Magico. Been doing a lot of reading about their S speaker line. Build quality seems superb. And there are many other fine manufacturers who put their heart and soul into what they design and build.

@Bombaywalla -- got a Q. Do most drivers remain linear through their selected pass-band with respect to time delay. In other words, when pulse testing a speaker, is it just the X-over that causes the tweeter to respond first, followed by the midrange, and then the woofer?

Regardless of the answer, if a manufacturer chooses to use a high order X-over for design considerations, is there anyway to compensate for the time delay phase distortion through the pass-bands of the drivers? Or is that analogous to unscrambling an egg. That is the damage is done ... no fixing it with more passives.

Not sure if this hit the point, but I own a self powered Paradigm subwoofer. The sub permits adjustments for loudness and frequency cut-off. But of relevance here, the sub permits phase alignment adjustments and I assure you ... it makes a big difference. Suck-out or no suck-out at the X-over point (35 Hz).

Cheers,

Bruce

@Ngjockey ... let me try to unpack what you just wrote. Let's assume we have a single dynamic cone speaker with a pass band of 35Hz to 20K Hz. Let's forget about high frequency beaming and cone breakup. Just assume this hypothetical speaker has a flat frequency response within its pass band, as measure on axis. Obviously no X-over needed here.

Now ... like all dynamic drivers, we have a voice coil, a spider, magnets, and so forth. Let's focus on your comment about the voice coil being inherently inductive. Makes sense. After all, we have a wire coil moving in a magnetic field, producing voltage and its own magnetic field. The faster it moves, presumably, the more voltage and back inductive reactance to the input signal.

Now, if a complex signal was fed into the speaker, would there be phase shifting with respect to the higher frequencies as compared to the low order fundamentals? To be more specific, say the signal was composed of a 100 Hz fundamental, plus "n" number of harmonics into the high treble. I assume this complex signal could be visually reproduced on an oscilloscope.

If the driver's output was compared to the input signal, would there be some sort of harmonic difference between input and output signals? Would the speaker's lack of inherent phase coherence be the cause of this distortion? Would this phase nonlinearity be caused by the inductance resulting from the voice coil moving in the speaker motor's magnetic field??

Let's assume the answers to my questions are -- yes?? Is there a frequency range where a speaker is phase coherent, or does phase nonlinearity increase as a function of frequency ... period??

If the answers to all of these questions are -- yes, then it seems to me using 1st order X-overs and sloped baffles is at best a rough justice engineering response to a problem that is inherent with dynamic speakers that use voice coils.

So ... where do we go from here?? Magneplaners, ESLs??

Cheers.

P.S. Bombaywalla and Al, feel free to chime in. I think I'm getting tangled up in my shoe-laces.

Thanks Bombaywalla. I read Roy's White Paper, but will re-read the sections you suggested.

Meanwhile, I just checked Stereophile's bench test report of the Maggie 3.5R and see that it is not time coherent. In fact, JA speculated that the midrange was connected in reverse polarity to the tweeter and woofer. I assume similar characteristics for the 3.7i.

Bombaywalla, I reread Roy's White Papers. He speaks to time and phase effects caused by speaker cone mass, suspension elasticity and damping. Nothing about phase shifting (if any) that may be caused by the inductive reactance of the driver itself, namely the voice coil moving in a magnetic field and producing back EMF. Perhaps Roy will catch my Q and share some thoughts.

If the driver's inherent inductance, as a stand alone factor, causes or contributes to nonlinear phase shifting, the challenge becomes a moving target.

Any ESLs out there that don't use X-overs??

Thanks Al ... caught that stat after I read your post. Didn't do the math, but I think that the DEQX would likely present an ok input impedance for my linestage even with the impedance buffer (330K ohms). Something north of 30K ohms if my "Jethro Bodeine double knot head cyphering" is right.

Still very fuzzy about this whole phase coherence conundrum. And even if its real, whether inserting the DEQX device in my signal path will hurt more than it helps.

The real problem is that there are so few B&M stores around, especially those that carry the gear in which I am interested, its hard to do serious listening and make rational decisions. Maybe an audio show??

I hate this hobby.

Bombaywalla, yes, your post is responsive and I get it. I still wonder out loud whether speaker inductance as a function of frequency response in fact remains constant within the speaker's pass band. Indeed ... even if speaker inductance remains constant as a function of frequency, wouldn't that also impact phase coherency?

I gather from your prior posts that the answer is "no" as long as inductance doesn't change. Then there will be no impact on phase coherency. Instead, phase coherency is effected only when there is a change in X-over reactance, albeit whether it is capacitive or inductive.

Al ... if you're catching any of this, please chime in. I think this is an important issue. Put it to you this way, my sense is that even if proponents and opponents of the importance (or not) of phase coherence want to argue yay or nay on the issue, it seems to me that phase shifting can't be good factor ... at best neutral.

BIF

Thanks again Bombaywalla. I caught the article. It doesn't speak to the impact of the speaker's electrical characteristics on phase coherence. Maybe it's just a non-issue.

@Tim ... based on the various posts in this thread, I gather there are not very many conventional speaker brands that are time and phase coherent. Vandersteen, Thiel and GMA come to mind.

As to your point about flat impedance and phase angle plots, take a look at the stats on the Magico S5 here:

http://www.soundstagenetwork.com/index.php?option=com_content&view=article&id=1043:nrc-measurements-magico-s5-loudspeakers&catid=77:loudspeaker-measurements&Itemid=153

Not saying the S5 is an easy speaker to drive because its impedance plot ranges for the most part between 3 and 4 ohms and its phase angle goes negative in the low bass, but overall pretty flat plots. I think my ARC Ref 150 could drive it ok off its 4 ohm taps, especially since my amp has a pretty muscular power supply - 1040 joules. OTOH, I would not try to drive the S5s with a low power SET amp. :)

I find the phase coherence issue to be extremely interesting. It's frustrating because without doing critical listening, it's hard to get one's "ears" around the issue.

Thanks Psag for bringing this important issue to our attention. Just not sure what to do with it. :)

BIF

Ngjockey ... I concur with your take on the S5 stats and build quality. As far as the X-over is concerned, not sure what you mean by unobtrusive, but I'd be willing to bet we're talking about 2nd and 3rd order X-overs here.

Fyi, I traded e mails with Magico tech folks about phase coherency. They freely admitted that the S5 is not phase coherent, but that attribute was a trade off in order to achieve other design objectives.

Gotta give these pups a listen!

Bombaywalla, sorry for the confusion. I'm referring to a driver's electrical, not mechanical, attributes. Rather than go off on a tangent, if Al catches these last few posts, he might be able to untangle what I'm trying to say. In the meantime, I'll just assume that the only relevant driver attributes that affect phase coherency are the mechanical points Roy discussed in his White Papers.

Psag ... just took a quick peek at the DEQX web site. Very interesting.

Problem is that it's not cheap and where is the vendor located? What recourse if it doesn't work well.

Also, it obviously entails inserting an artifact into the signal path, presumably between source components (e.g., CDP, DAC and phone pre) and linestage. Oftentimes, not the best thing to do. How does it work if one has an integrated amp with built-in phono section??

Sure wish I could try the device on approval.

Cheers,

BIF

Next week, I'm planning to do some fact finding about the DEQX device. Short of outboard active crossovers, I'm starting to get the sense that mechanical (e.g., sloped baffles) and electrical (i.e., 1st order X-overs), at best, does rough justice. I'll be back.

Psag ... so you say the device is inserted in between the pre amp/linestage and amp?? Well here's a little quandary I may have.

My ARC REf 5 SE linestage has to see a combined impedance of not less than 20K ohms. As currently configured, the Ref 5 sees 300K ohms off Main 1 - imput imp. of amp and 337K ohms off Main 2 - imput imp. of custom made subwoofer/impedance buffer/channel summing gizmo. The combined impedance is about 157K ohms. Well north of 20K ohms.

Any idea what the DEQX input impedance is. As you can see .. kinda important.

Thnx

I think a call to the US Distributor may be in order. Lew... I agree that the DEQX is likely NOT plug and play. From what I picked up from the DEQX web site, one can pay extra for a remote professional set up. To me ... that is just part of the cost.

Honestly, I am a frustrated scientist. This stuff is very interesting to me. Problem is my IQ isn't high enough to get the math and science. My math skills are just a little north of the "Jethro Bodeine double-knot head cyphering" level.

Here's a guess ... I surmise that if the DEQX's hype is fairly stated, it may do more for my rig than stepping up to $25+ Magicos S speakers. There is nothing wrong with the drivers in my Paradigm S8s. We're talking about a low distortion beryllium tweeter, an aluminum/cobalt mid and polypropylene/mineral infused woofers. I have a sub to augment bass roll-off. The basics are all there.

I'll report back.

Cheers.

P.S. I have a better chance of sneaking the DEQX into my house than new speakers. That factor alone weighs heavily in favor of the DEQX. :)

Al -- you are always the voice of reason. What are your thoughts? Could this be transformational or is that un likely?

Al's last post is what I needed to take the next step. A call into DEQX is in order. For some reason, my gut tells me I might get more bang for the buck going in this direction than by dropping a wad of cash into expensive speakers. I'll be back.

Al -- off topic, but there's another speaker cable thread running. I asked a serious question. If you catch the thread, please share your thoughts there. If not, my question is why wouldn't heavy gauge romex (say 10 or 12 gauge) make for good speaker cables?? What electrical properties would expensive designer cables have that heavy romex lacks. Isn't this all about resistance, inductance and capacitance?? Is there some other electrical voodoo or snake oil I am missing???

Thanks Roy. For those of us time and phase dummies who have already invested in expensive gear, and who are confounded by the difficulties associated with meaningfully auditioning speakers, what are your thoughts about using the DEQX unit to unscramble the time coherence egg?

As an fyi, which I may have mentioned in this thread or elsewhere, I auditioned a pair of Vandies and another speaker (Brand X). All conditions were held constant. Notably, the amp was the same model as my former amp. I struggled to get happy with the Vandy Treos. Spent close to 90 minutes with them. Played all kinds of music. Moved my listening chair forward, backwards, sideways. Even listened backwards. :)

I was getting ready to walkout and the dealer offered to compare another speaker that is similar to mine. Same set up, amp, etc. Brand X ate the Vandy's lunch. It wasn't even close.

Maybe I like sonic swill??? Dunno

Back to my Q: Any thoughts or comments about the DEQX??

Unsound, are all of the companies listed in your last post still making time coherent speakers. Of course, Vandersteen, Thiel and GMA are obvious. Not sure about the others.

Btw, been in contact with DEQX. Will try and arrange a home demo. If I can pull it off, I'll report back.

Unsound, not sure I understand your question. You ask why the DEQX "system approach includes analog conversion rather than keeping the whole stream in the digital domain?" Perhaps ... it is because the device is inserted in between the source components and the power amp. Seems that at some point the device has to go digital to analogue in order to drive the amp.

Am I misunderstanding your question?

I hope to hear back from DEQX this week. I've got to nail this time coherence issue one way or the other.

Btw, I been shopping around for insulated 10 gauge solid core copper wire. I intend to make my own speaker cables. May cost me $15 bucks ... gasp!

Thanks Roy. I think I have the instinct, but not the brains for the math and physics. B'li neder (not a vow), I will teach myself the math and physics when I retire as Caeser's tax collector.

So ... I'm all set up. Nice electronics, good music ... listening to some hi-rez redbook CDs right now, ... good looking wife and ok speakers. Why not just go for the DEQX and call it a day?

Btw, just anecdotally and IMO, I think my Paradigm S8s (v3) are made of decent kit: beryllium tweets, aluminum-cobalt alloy mids, good woofies, tweets and mids are ferro-fluid cooled and damped, super neodymium magnets in the tweets and mids, 20,000 gauss magnetic flux density in the tweets and 15K gauss magnetic flux density in mids and woofies. What am I missing except time coherence?

Why not DEQX?

Bombaywalla, not trying to be a troll here. I restated my DEQX point because I already have speakers. However, as Lewinskih01 kinda alluded to above, the device may not be perfect ... for all the reasons Roy mentioned, but it may get me to a much better place.

Trying to arrange for a DEQX audition.

Kudos to Roy for his well written posts and dedication to our hobby.

Here's a simple un-tweak that may have helped just a little tweak (pun)... dunno.

For the longest time, I lifted the back of my speakers so they tilted forward. Here the old thought process:

My listening position is below the level of the tweeters. The speakers are about 44 inches high and my listening position is about 10 feet back. But my couch sits very low. I thought that by tilting the speakers forward, the tweeters would beam directly at me and treble would be improved.

Here's my current thinking, courtesy of this thread:

Lifting the back of the speakers as described may have augmented treble response, but the tweeter voice coils are even more forward of the mid and woofer driver voice coils than before the tilt forward. So ... to the extent there was time incoherence before, I'm just augmenting it.

So, at the expense of maybe losing a little treble, I attenuated an already non-optimal time incoherent situation just a tad.

Bottom line: it's probably in my head, but I think the speakers sound a little better. Little less bassey, a tad more coherent and invisible.

Btw, a couple of weeks ago, I switched back to the 4 ohm taps on my amp. There's definitely a noticeable change in coloration because the output impedance off the 4 ohm taps is lower -- and output voltage regulation is tighter. Bass is tighter and more extended. Upper mids/low treble are less bright.

But I also think the amp is "happier" with the load presentation because a good part of the speaker's power delivery demands are in the bass/low midrange region which specs at 4 ohms (70 Hz to 700 Hz). IOW, better impedance matching with the amp where it counts the most.

Still want to check out the DEQX.

Cheers,

BIF

Roy, do you think my "un-tweak" re tipping my speakers back could have attenuated my speakers' time incoherency as I described above? Or is it just wishful hearing?

Roy,

I looked up Zobel circuits on Wiki, but the theory got beyond me. Can you please explain what a Zobel circuit does in the context of speakers.

For example, my speakers have an impedance peak of 20 ohms at the mid/tweeter x-over point. Would a Zobel change the impedance presented to the amp.

At what cost? Less efficiency? Distortion? Does the Zobel introduce something into the circuit that wasn't there before. Nothing good comes at a cost of nothing bad.

Thanks

Bruce

@Roy: Gotcha. As you say, the Paradigm Sig 8 (v3) 20 ohm peak may be high because Paradigm uses a 3rd order x-over at the mid/tweeter driver x-over point. What's that? About 24 db/octave??? Practically a brick wall filter.

Incidentally, it occurred to me that if the x-over screws up timing between the various drivers, with a 24 db x-over will frequencies covered by JUST the tweeter be out of phase within the pass-band covered by the tweeter, i.e., 2000 Hz to 45K Hz??

If not ... that's a large part of the acoustic spectrum that (2K to 20K Hz) IS phase coherent.

Just asking.

Btw, when I play my stereo, the neighborhood dogs sit on my front lawn and howl. I guess the high frequencies drive them crazy. Even my poor wife howls. LOL

Btw, btw, quality beryllium tweeter break up in the high ultrasonic range. They are super brittle, super light, and super fast. Don't know how the Be tweets compare to ribbons, but the Be tweets might give a good ribbon a run for its money.

I recall that you buy some of your drivers from Denmark. I think SEAS and/or ScanSpeak makes Be tweets. Have you ever considered using them for your speakers? Only problem I can think of is that Be is toxic. That's why I use a gas mask when I listen to my rig. HaHa. LOL