Heavy gauge speaker wire versus ACD technology

megasat16

Two scary scenario here and I think they are equally scary and impressive.

1. The wrong guy with the right detonate button
2. The right guy with the wrong exit button

Anyway, food for thoughts.

A.) Are the drivers in SDA 2B shared the internal cabinet space? If so, the pressurization of the regular driver will cause the dimensional driver acting as a mini-PR along with a Big PR even when the dimensional driver has no signal coming to it.

B.) If the above case is true, then, the lobing effect you theorized will be less apparent in actual listening. This will effect the real efficiency of the regular driver though.

C.) When the dimensional driver has signal coming from (L-R or R-L), it may cause phase shift from the regular driver if they don't share the same XO. It's causing what I think would be a dimensional stereo effect. Since the phase shifts occurs, SPL plots will likely varies with the signal fed to it (dips or bumps).

D.) If above statement C. is true, you can't use the regular SPL measurement method to correctly plot the SPL curve which is a shame.

Well, I might be 100% way off base but it's my humble observation.

megasat16

Would someone tell me where to get the Schema of the SDA (and 2B in this particular case)?

ohskigod

does a PHd mandate creating a wiki page for your online username?

http://en.wikipedia.org/wiki/User:Jcandy

juuuuuuust chuckin it out there kids.

tonyb

ohskigod wrote: »

does a PHd mandate creating a wiki page for your online username?

http://en.wikipedia.org/wiki/User:Jcandy

juuuuuuust chuckin it out there kids.

Now that there is funny, btw, great previous post Lou.

ohskigod

https://fusion.gat.com/~candy/resume08.pdf


cough cough, can't be certain, but boy does it fit an M.O.

megasat16

megasat16 wrote: »

Would someone tell me where to get the Schema of the SDA (and 2B in this particular case)?

Nevermind, I found the SDA schema.

heiney9

Jcandy

Here's a professional review with measurements (since you are measurement guy). It seems your theory about lobing is way off. It also gives you a much better understanding about how the drivers are integrated into the SDA model.

http://www.polksda.com/sda1creview.shtml

H9

inspiredsports

megasat16 wrote: »

Two scary scenario here and I think they are equally scary and impressive.

1. The wrong guy with the right detonate button
2. The right guy with the wrong exit button

Anyway, food for thoughts.

A.) Are the drivers in SDA 2B shared the internal cabinet space? If so, the pressurization of the regular driver will cause the dimensional driver acting as a mini-PR along with a Big PR even when the dimensional driver has no signal coming to it.

B.) If the above case is true, then, the lobing effect you theorized will be less apparent in actual listening. This will effect the real efficiency of the regular driver though.

C.) When the dimensional driver has signal coming from (L-R or R-L), it may cause phase shift from the regular driver if they don't share the same XO. It's causing what I think would be a dimensional stereo effect. Since the phase shifts occurs, SPL plots will likely varies with the signal fed to it (dips or bumps).

D.) If above statement C. is true, you can't use the regular SPL measurement method to correctly plot the SPL curve which is a shame.

Well, I might be 100% way off base but it's my humble observation.

Bingo!

inspiredsports

ohskigod wrote: »

does a PHd mandate creating a wiki page for your online username?

http://en.wikipedia.org/wiki/User:Jcandy

juuuuuuust chuckin it out there kids.

. . . hurts his own arm patting himself on the back.

jcandy

ohskigod wrote: »

does a PHd mandate creating a wiki page for your online username?

http://en.wikipedia.org/wiki/User:Jcandy

juuuuuuust chuckin it out there kids.

Whoa, great find. EVERYONE who contributes to wikipedia automatically gets such a "user" page associated with their WIKI username, that's why the prefix "user" precedes the name. Its like your profile page at Club Polk.

jcandy

megasat16 wrote: »

A) Are the drivers in SDA 2B shared the internal cabinet space? If so, the pressurization of the regular driver will cause the dimensional driver acting as a mini-PR along with a Big PR even when the dimensional driver has no signal coming to it.

Yes. Because this is guaranteed to happen at low frequency, the SDA effect is "terminated" by the large inductor below about 50Hz.

megasat16 wrote: »

B.) If the above case is true, then, the lobing effect you theorized will be less apparent in actual listening. This will effect the real efficiency of the regular driver though.

The lobing effect completely depends on music content, yes. Honestly, I would have to do simulations to figure out what is happening.

megasat16 wrote: »

C.) When the dimensional driver has signal coming from (L-R or R-L), it may cause phase shift from the regular driver if they don't share the same XO.

They do share a crossover. With the SDA cable connected, there is a single circuit.

megasat16 wrote: »

D.) If above statement C. is true, you can't use the regular SPL measurement method to correctly plot the SPL curve which is a shame.

Yes. This caveat is noted and discussed on the measurement page.

megasat16 wrote: »

Well, I might be 100% way off base but it's my humble observation.

Perfectly fine observations.

megasat16

jcandy wrote: »

Perfectly fine observations.

Sorry! My previous observation was wrong coz I assumed the Dimensional driver is sitting idle till the L-R or R-L effect kicks in.

I found the SDA diagrams, schema and looked through it. The Dimensional Driver is always connected to the signal regardless of the SDA interconnect. It will play and not sitting idle. :eek:

When the R-L or L-R effects kick in, the overall SPL change (bumps or dips) in either Right or Left speaker will happen based on the frequency and the phase shift.

Face

Face wrote: »

Unless they were hooked up or set up incorrectly, based on Polk's reduction of the effects of interaural crosstalk alone, the 2B's should have a wider soundstage.

jcandy wrote: »

Of course they were set up correctly. In fact, I first set up these same speakers for my uncle in 1990. At the time, they were probably the best speakers I'd ever heard. My love for Polk started in about 1980, when as a kid in junior high school, I heard the monitor 10s in the local high-end hi-fi store. But is 2011 now and its possible to make a much better speaker using computer optimization, and incorporating the lessons learned since then. Is Polk, or anyone, still using the SDA crossover design?

I can give you one reason why you wouldn't want to: lobing. You get horrific lobing with the SDA effect, which leads to an unnatural sound. To my ears, in comparison to a really accurate speaker, the SDAs sound somewhat like they're playing in a well-damped hallway. That is largely due, IMO, to a major dip in the crossover region. IOW, I can hear the problem in the crossover.

So did they or did they not have a wider soundstage?

FTGV

Face wrote: »

So did they or did they not have a wider soundstage?

One would certainly expect it to be since that is the intended goal of the design.However is this increased SDA derived soundstage width always superior to and more natural sounding then say the precise imaging one can get from a well engineered point source mini monitor?

jcandy

Face wrote: »

So did they or did they not have a wider soundstage?

Wide soundstage is not the language I'd use to describe the SDA. When I auditioned them, nobody commented on the "wide soundstage", although people all were immediately impressed with the bass. IMO the soundstage is what you would expect from a speaker with a very large frontal baffle area.

The major impressions I get from the SDA2B are (1) great bass (in comparison to much smaller designs which currently dominate the market), (2) something funny/nasal in the mid, as if the speaker was playing in a "damped" hallway.

In comparison, the mid and high of the BAMTM were subjectively more clear, open, natural, whatever that means. The SDA2Bs have an impressive but unnatural sound IMO.

heiney9

Ok, Jcandy I've asked you to clarify one thing twice in another thread you ignore so I can assume 1) you agree 2) you can't counter 3) you are just ignoring.

I asked if you would read the professional review about SDA's with measurements and see that your assumptions are a little out line. You seem to be willing to counter other's statements yet you are mute when I am trying to give you some of the theory and measurements you so desperately grasp to.

If you only going to selectively respond in this discussion based on suppositions and not real facts, then I'm done here............I'm sure you really don't care either way.

H9

megasat16

FTGV wrote: »

One would certainly expect it to be since that is the intended goal of the design.However is this increased soundstage width always superior to and more natural sounding then say the precise imaging one can get from a well engineered point source mini monitor?

ZVM5? May be hard to say.

It's like asking whether you like Britney Spears or Kim Kardashian?

Anyway, I want to know what Mike Says! :biggrin:

jcandy

FTGV wrote: »

One would certainly expect it to be since that is the intended goal of the design.However is this increased soundstage width always superior to and more natural sounding then say the precise imaging one can get from a well engineered point source mini monitor?

Related to that point, people also praised the ZMV5, preferring it to the Paradigm Studio 20 for vocals and upper octave content. The problem with the ZMV5 is that the significant lack of bass extension always gets in the way of a clear comparison. The ZMV5, however, are easier to get on my desk than the SDA2Bs.

jcandy

heiney9 wrote: »

I asked if you would read the professional review about SDA's with measurements and see that your assumptions are a little out line.

Of course I read it, well before I did any measurements. What is your specific issue?

FTGV

megasat16 wrote: »

ZVM5? May be hard to say.

No James I meant any good imaging non SDA speaker.

heiney9

FTGV wrote: »

One would certainly expect it to be since that is the intended goal of the design.However is this increased SDA derived soundstage width always superior to and more natural sounding then say the precise imaging one can get from a well engineered point source mini monitor?

I wouldn't use the word ALWAYS (you've scolded me before using absolutes ) but yes, I would say in many instances cancelling interaural crosstalk is the more natural way to listen and much closer to how we hear things in real life vs. precise imaging from a point source.

I get none of the issues JCandy has with is SDA's. No nasal sound, no lobing issues no "damped hallway" issues, etc.

H9

megasat16

FTGV wrote: »

No James I meant any good imaging non SDA speaker.

In General Case, the answer lies in the question, I suppose.

I guess the word "Point Source" is a given. :biggrin:

FTGV

megasat16 wrote: »

I guess the word "Point Source" is a given. :biggrin:

Well I also wanted to rule out bi and dipoles.

megasat16

FTGV wrote: »

Well I also wanted to rule out bi and dipoles.

Only if the Imaging is ABSOLUTE factor in Sound Quality and Imaging.

IMO, Sound Stage includes many factors and Imaging is just one of the game in the Sound stage. :biggrin:

Personally, No Box No Point Source Will Beat Dipole OB Array and Period!

Of Coz, even with everything such as well thought out design and components selection, etc.

Let's don't forget waterfall...speed, resolution, recovery, change.

Face

Here are some related threads from the scientific types at DIY Audio. Fortunately, they don't all share the same opinion as Mr. Candy.

http://www.diyaudio.com/forums/multi-way/181064-we-know-frequency-response-isnt-end-all-all-so-what-else-there.html

http://www.diyaudio.com/forums/multi-way/166411-measurements-when-what-how-why.html

jcandy

Face wrote: »

Here are some related threads from the scientific types at DIY Audio. Fortunately, they don't all share the same opinion as Mr. Candy.

http://www.diyaudio.com/forums/multi-way/181064-we-know-frequency-response-isnt-end-all-all-so-what-else-there.html

http://www.diyaudio.com/forums/multi-way/166411-measurements-when-what-how-why.html

Great links. You will note the two quotations (from two of my gurus) from first post of the second thread:

Zaph:

All the answers are in the measurements. And I mean ALL the answers. Some people don't know how to interpet the measurements. Some don't want to know all the answers.

Geddes:

These things are all measureable. Just because you don't know how to do it does not mean that it cannot be done.

steveinaz

Just "opinions" nothing new here...

Simply using waveforms as a comparison is like saying 2 speakers that are different, but measure the same, will sound the same. It's over-simplistic in the extreme, and leaves nothing to the tactile experience of actually "listening."

...and that is just my opinion.

heiney9

Nm.........

heiney9

jcandy wrote: »

Of course I read it, well before I did any measurements. What is your specific issue?

Here's what one speaker engineer has to say about lobing:

Frequency also affects dispersion, as Paul explains.

"If I place the microphone in the center of the speaker I only know how the sound disperses on-axis. I don't know how the dispersion is changing at other angles around the speaker. Even if a speaker has a great on-axis response, it will sound terrible if the dispersion is narrow. The reflected sound interferes with good, direct sound," he says. "But what I do know is that dispersion diminishes as frequency increases. As the wavelengths become very, very small and the dispersion gets narrower, the sound will begin to emit like a laser beam."

This occurs because dispersion is dependent on the length of the wavelength relative to the radiator. If the wavelength is long relative to the size of the radiator, there will be good dispersion. Therefore, as the frequency the driver reproduces increases, its wavelength decreases until it is too short and then the driver will begin to "beam" the high-frequency sound. With a tweeter, beaming usually occurs at frequencies beyond our perception; however, with a midrange, the poor dispersion will be noticeable. And speakers with beaming problems will create "sweet spots" in the room.

"We call this lobing," continues Paul. "For instance, you have a speaker with two drivers and a tweeter in the center, and these two drivers interact together at some frequency. If it happens to be a frequency that is proportional to the distance the drivers are apart, lobing occurs. Plotted on a circular curve, lobes have weird shapes -- flowers, butterflies -- you get very exotic interference patterns between two sources."

Lobes occur off-axis and are large fluctuations in frequency response that cause poor sound for anyone not listening on-axis. When one sits off-axis he may be listening to the interference of lobing. This explains why my dad's speakers sounded best only when he sat in his La-Z-Boy -- everywhere else in the room was off-axis, and lobes were interfering with the speaker's sound.

Now if one reads the review done by Stereo Review, they pretty much say the exact opposite of the above.

Meaning the horizontal dispersion both on-axis and off-axis was excellent so that sort of puts a few holes in your theory about SDA's having severe lobing.

Of course feel free to provide some solid measurements of your own to prove Stereo Review and the rest of us are full of it.

H9

heiney9

I also find it incredibly odd that you live and die by measurements yet the only thing you have to say about the SDA's is your subjective listening impressions. If we give our subjective listening impressions about break in or cables, etc, you ask us to support it with science.

I am simply asking that you are held to the same level of accountability.

H9