Custom built Cabinet (SDA) ??
Comments
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Then specifically which model are you guessing has the pitched drivers as there are many different models mentioned in this thread.
Also since clearly its not a common known attribute and thus not critical to the SDA effect (or it would be well known and documented in all models) I don't suppose its going to be too critical to a home made set? eh?Too much **** to list.... -
OK the article is talking about the acoustic centers of the drivers being offset by 20 degrees.The acoustic center can be roughly aproximated as where the voice coil meets the cone or dome so the acoustic center of the midbass will be behind the tweeters.Mounting the midbass units at a slight 3-4 degree angle would IMO have an insignificant effect since it's only operating up to 2-2.5 khz.
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So let me see if I understand you FTGV.
If you draw an isosceles triangle from left to right to sweet spot the angle from the sweet spot to the driver center is 3 or 4 degrees different then that to the tweeter center?
If thats the case I'd believe that. But to purposefully manufacture a 3-4 degree angle in the cabinets.....not so much.Too much **** to list.... -
Because of tweeters acoustic center being further forward than that of the midbass's,mounting the tweeter outside of the stereo array drivers adds enough delay so that the sound of the tweet and midbass arrive to the ear at the same time.The resulting lobe is claimed to be angled inward at 20 degrees.Thus the recommendation for no toe in as it would increase this angle of radiation inward too much.So let me see if I understand you FTGV.
If you draw an isosceles triangle from left to right to sweet spot the angle from the sweet spot to the driver center is 3 or 4 degrees different then that to the tweeter center?
If the drivers are flush mounted how can they possibly be angled to any degree unless it was the entire baffle.?Like I said previously IMO 3-4 degree angling of the midbass drivers would have little effect IMO.If thats the case I'd believe that. But to purposefully manufacture a 3-4 degree angle in the cabinets.....not so much. -
I get what your saying about the tweeter not having a center of radiation like a driver.
What I am saying about the 3-4 degree difference between the center of the tweet and the center of the driver arrays is if you draw a line vertical from the floor through the center of the drivers and then one through the center of the tweeters then draw a line from that center to the sweet spot the drivers would be about 3-4 degrees left or right of the tweeter center.
That's about the best idea I have for an understanding or explanation of what Heiney is saying. Though its still a big difference from that to having a pitch machined into the cabinet.Too much **** to list.... -
The internal volume would be the same as the 1.2tl's and the cabinet height would be the same as the 2.3tl's, only it would be deeper.
I'm thinking an increase in depth would affect the passive radiator response, but I could be talking out of my a$$.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
Though its still a big difference from that to having a pitch machined into the cabinet.
Yeah, there's no pitch to the driver mounts.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
If internal volume is the same and box isn't over damped the PR response should'nt be effected.
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I would think that internal volume has more of an impact on the passive than the distance between it and the back wall of the cabinet.The Gear... Carver "Statement" Mono-blocks, Mcintosh C2300 Arcam AVR20, Oppo UDP-203 4K Blu-ray player, Sony XBR70x850B 4k, Polk Audio Legend L800 with height modules, L400 Center Channel Polk audio AB800 "in-wall" surrounds. Marantz MM7025 stereo amp. Simaudio Moon 680d DSD
“When once a Republic is corrupted, there is no possibility of remedying any of the growing evils but by removing the corruption and restoring its lost principles; every other correction is either useless or a new evil.”— Thomas Jefferson -
It seems to me that the sound waves would have to travel farther, therefore slowing down the PR response.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
The tweet and mid bass both have an acoustic center.Since it is approximately where the voicecoil meets the cone or dome is much further forward on the tweeter.I get what your saying about the tweeter not having a center of radiation like a driver. -
While we are discussing the re-invention of the wheel here, would it be at all possible to incorporate ribbon tweeters into the mix?The Gear... Carver "Statement" Mono-blocks, Mcintosh C2300 Arcam AVR20, Oppo UDP-203 4K Blu-ray player, Sony XBR70x850B 4k, Polk Audio Legend L800 with height modules, L400 Center Channel Polk audio AB800 "in-wall" surrounds. Marantz MM7025 stereo amp. Simaudio Moon 680d DSD
“When once a Republic is corrupted, there is no possibility of remedying any of the growing evils but by removing the corruption and restoring its lost principles; every other correction is either useless or a new evil.”— Thomas Jefferson -
Sure, but then you're into the world of having a frankenpolk.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
It seems to me that the sound waves would have to travel farther, therefore slowing down the PR response.
I would think the PR is moved by air volume not sound waves in a semi sealed cabinet.Too much **** to list.... -
Sure, but then you're into the world of having a frankenpolk.
building entirely new cabinets already puts us there imho.:cool:The Gear... Carver "Statement" Mono-blocks, Mcintosh C2300 Arcam AVR20, Oppo UDP-203 4K Blu-ray player, Sony XBR70x850B 4k, Polk Audio Legend L800 with height modules, L400 Center Channel Polk audio AB800 "in-wall" surrounds. Marantz MM7025 stereo amp. Simaudio Moon 680d DSD
“When once a Republic is corrupted, there is no possibility of remedying any of the growing evils but by removing the corruption and restoring its lost principles; every other correction is either useless or a new evil.”— Thomas Jefferson -
Yeah, there's no pitch to the driver mounts.
Yeah, well I read it somewhere over the years and stuck it in my long term memory. Just can't recall where. Anyway that's the least critical of all the baffle properties one needs to consider and be exactly precise about if you are going to recreate a new cabinet. Internal and external dimensions are a piece of cake. Proper mounting of the drivers is critical to maximize SDA properties. However there is enough technical info out there to get it done.
Just found my Compendium and reread the original SDA white paper, fascinating read and explains SDA the best. Some may have to look beyond the math calculations so you aren't side tracked. The concept and execution theory are right there for the reading.
H9"Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul! -
Because of tweeters acoustic center being further forward than that of the midbass's,mounting the tweeter outside of the stereo array drivers adds enough delay so that the sound of the tweet and midbass arrive to the ear at the same time.The resulting lobe is claimed to be angled inward at 20 degrees.Thus the recommendation for no toe in as it would increase this angle of radiation inward too much.
The tweet and mid bass both have an acoustic center.Since it is approximately where the voicecoil meets the cone or dome is much further forward on the tweeter.
What I'm taking here is you are speaking of a vertical 20 degree off set,no?
I am speaking of a horizontal off set of 3-4 degrees.Too much **** to list.... -
nooshinjohn wrote: »While we are discussing the re-invention of the wheel here, would it be at all possible to incorporate ribbon tweeters into the mix?
It's recreation of the original, not re-inventing the wheel.
BIG difference.
H9"Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul! -
Going off track for just a second since internal volume was mentioned, Now I now it is important but the CRS+'s and 2B's have the same crossovers/drivers and tweeters. the only thing different is the PR and "internal volume". how is it that it seems this rule does not apply here?? what am I missing??
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What I'm taking here is you are speaking of a vertical 20 degree off set,no?
No, read carefully
thus the effective axis of radiation, is shifted by an angle of 20* toward the listener."Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul! -
How can you have a center of radiation and a 20* shifted axis?Too much **** to list....
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It's recreation of the original, not re-inventing the wheel.
BIG difference.
H9
Correct!!! -
As I pointed out it's 20 deg inward meaning horizontally.What I'm taking here is you are speaking of a vertical 20 degree off set,no?
I am speaking of a horizontal off set of 3-4 degrees. -
The angle created by having the woofers acoustic center physically further back than the tweeters angles the main lobe toward the listener.Visualize the resulting angle when drawing a line from the center of the midbass's dust cap to the dome of the tweeter. .How can you have a center of radiation and a 20* shifted axis? -
As I pointed out it's 20 deg inward horizontally.
Exactly! so then the tweeter isn't effectively radiating from center. And with that understanding the 3 degree would be between the tweeter offset and the stereo driver array and the 4 degree would correspond to the SDA array.
I'm just trying to figure what Heiney was reading to think there was a planar difference. The reason being...I have some literature somewhere that speaks of a 3-4 degree difference as well but I believe it was based variable on the actual distance between speaker front and sweet spotToo much **** to list.... -
The angle created by having the woofers acoustic center physically further back than the tweeters angles the main lobe toward the listener.Visualize the resulting angle when drawing a line from the center of the midbass's dust cap to the dome of the tweeter. .
I'm with ya on that one bro. It's not the plane I am speaking of though.Too much **** to list.... -
How can you have a center of radiation and a 20* shifted axis?
Cool,I was just responding to the ? above.I'm with ya on that one bro. It's not the plane I am speaking of though. -
The optimum axis would likely be with ears at the mid point between the midbass and tweet. with a small window of a few degrees in either direction where response is not altered greatly.Is that what you are alluding to?. It's not the plane I am speaking of though. -
All things considered this project has me thinking. I have another facet to throw into the mix though. How thick would the steel have to be t o eliminate any resonance. For some reason I have this picture of a set made of polished stainless or possibly a powder coated option. My first thought would be to start in the 1/2" plate and go thicker from there. on thing is for sure. You wouldn't need to back up with a set of Larrys amazing rings lolToo much **** to list....
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The optimum axis would likely be with ears at the mid point between the midbass and tweet. with a small window of a few degrees in either direction where response is not altered greatly.Is that what you are alluding to?
Sort of. If you draw a line from your forehead (that is in the sweet spot) to the center of the stereo arra ,tweet and sda array the line on the stereo array would be 3 degrees off of canter and the sda array would be 4 degrees in the opposite direction off center.Too much **** to list....
