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post #631 of 651 Old 04-21-2014, 03:29 AM
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^^^^^

 

This also reminds me of the constant need, to satisfy some, of caveating every point one ever makes. Miss out any part of the caveat and someone will jump on you with the extreme case that you never thought in your wildest imaginings anyone could ever use as a contrary example. So if I say 'biwiring is a waste of time and wire' but I omit to mention that if one is using bell wire as speaker cable, then biwiring might have some useful effect, I know I will be jumped on by someone who brings up this point, even though it should be blindingly obvious that I am not considering the use of bell wire as a serious factor in the discussion. Maybe we should collect all the caveats into one place, number them, and then simply add "Refer to caveat #017" to each relevant post. ;)

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post #632 of 651 Old 04-21-2014, 03:32 AM
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Originally Posted by David Susilo View Post

Depending on the listening distance, speaker position, room size, etc, it is possible to have a room without additional treatment.

 

So what sort of room wouldn’t need some form of treatment then?

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post #633 of 651 Old 04-21-2014, 03:33 AM
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^^ I agree with that kbarnes. And some are really, really annoying at picking nits. maybe they really wanted to be lawyers.

But WRT size, efficiency and 3dB corner, doesn't Hoffman's Iron Law sum it up concisely enough?

My main sub drivers are 96.9dB/2.82V/1m. Vas is 521L though......
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post #634 of 651 Old 04-21-2014, 05:14 AM
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Quote:
Originally Posted by kbarnes701 View Post

Quote:
Originally Posted by David Susilo View Post

Depending on the listening distance, speaker position, room size, etc, it is possible to have a room without additional treatment.

So what sort of room wouldn’t need some form of treatment then?

Obviously, a room that came out just right due to pre-existing furniture and architectural features.

In theory this can happen, but in the real world it seems unlikely.

I think a relevant question is this:

Look at pictures of professionally designed listening rooms. Which ones have nothing in them that the experienced eye cannot detect as either being an obvious acoustic treatment or something(s) that are stealthy acoustic treatments?

My own informal survey says: "Not so much".

A good place to run this test is http://www.madronadigital.com/Gallery/Gallery.html. It seems to be a great example of stealth. I recognize some high value wall and ceiling treatments in some of the pictures. Rule of thumb - if you can't find the speakers the room treatments are probably at least as stealthy.

Or look here for representatives of the "Play them like you got them" school of audio equipment and room treatments. http://www.houzz.com/small-home-theater-design

Or sites like this that let it all hang out: http://www.mycinematech.com/theater_main.php

Google is your friend!

About as obvious is that if there is a broad range of acceptable outcomes, then the range of rooms that need no further treatment is also broader. IOW if you are willing to tolerate greatly suboptimal sound, then your room will need less work. Like SPL preferences, that if very personal.
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post #635 of 651 Old 04-21-2014, 06:15 AM
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Originally Posted by arnyk View Post
 
Quote:
Originally Posted by kbarnes701 View Post
 
Quote:
Originally Posted by David Susilo View Post

Depending on the listening distance, speaker position, room size, etc, it is possible to have a room without additional treatment.

So what sort of room wouldn’t need some form of treatment then?

Obviously, a room that came out just right due to pre-existing furniture and architectural features.

In theory this can happen, but in the real world it seems unlikely.

I think a relevant question is this:

Look at pictures of professionally designed listening rooms. Which ones have nothing in them that the experienced eye cannot detect as either being an obvious acoustic treatment or something(s) that are stealthy acoustic treatments?

My own informal survey says: "Not so much".

A good place to run this test is http://www.madronadigital.com/Gallery/Gallery.html. It seems to be a great example of stealth. I recognize some high value wall and ceiling treatments in some of the pictures. Rule of thumb - if you can't find the speakers the room treatments are probably at least as stealthy.

Or look here for representatives of the "Play them like you got them" school of audio equipment and room treatments. http://www.houzz.com/small-home-theater-design

Or sites like this that let it all hang out: http://www.mycinematech.com/theater_main.php

Google is your friend!

About as obvious is that if there is a broad range of acceptable outcomes, then the range of rooms that need no further treatment is also broader. IOW if you are willing to tolerate greatly suboptimal sound, then your room will need less work. Like SPL preferences, that if very personal.

 

So pretty much the answer that David Susilo failed to give me the first time I asked.  I guess I could summarise your full reply with "pretty much none".  But I’d be interested in David's answer as he seems to be saying that there are some rooms which will not need some form of acoustic treatment, or rooms that won't benefit maybe.

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post #636 of 651 Old 04-21-2014, 07:07 AM
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Originally Posted by UndersAVS View Post

Tunnel vision. Happens when someone feels the discussion is about winning an argument.
If we look at this situation objectively, that is the case with every vocal poster here. I can't imagine saying otherwise and be truthful. As men, we have a hard time accepting this about ourselves but routinely use the tactic against the others.

I'm always glad to see someone speaking for themselves, and just themselves. ;-)

I don't care if I win or lose an argument. I've already won so many arguments in my 67 years that plus/minus one more means very little.

I'd rather lose an argument and learn something that I was either wrong about or didn't know about. I'd rather be correct a lot of the time than "Always be right".

I'd even rather argue to a draw and have my breadth of understanding broadened.

YMMV! ;-)
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post #637 of 651 Old 04-21-2014, 08:08 AM
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Originally Posted by arnyk View Post

Obviously, a room that came out just right due to pre-existing furniture and architectural features.

In theory this can happen, but in the real world it seems unlikely.


...About as obvious is that if there is a broad range of acceptable outcomes, then the range of rooms that need no further treatment is also broader. IOW if you are willing to tolerate greatly suboptimal sound, then your room will need less work. Like SPL preferences, that if very personal.

Just to be clear since my comment started this line of thought--I found out as a newbie that my limited speaker placement was enhanced by my choice of it being a small library with irregular walls and ceilings. I realize if I actually download and use REW I would learn more including where my deficiencies lie and possibly could remedy (or more that likely be obsessed by correcting) them--That said, I really like the sound of my system and it's usually only me, with the exceptions my wife when wants to watch a movie and we do listen at/or near Reference Level and both enjoy the sound....

We also have a rather large room with our second system (Dojang, by coincidence ) and a 5.1 system that definitely could benefit from room treatment and the speakers can be moved, but not much critical listening is done...Usually loud Multichannel Rock where I am singin' as well. eek.gifcool.gif

For the record--I wasn't downplaying the benefit or room treatment or using REW.
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I'm always glad to see someone speaking for themselves, and just themselves. ;-)

I don't care if I win or lose an argument. I've already won so many arguments in my 67 years that plus/minus one more means very little.

I'd rather lose an argument and learn something that I was either wrong about or didn't know about. I'd rather be correct a lot of the time than "Always be right".

I'd even rather argue to a draw and have my breadth of understanding broadened.

YMMV! ;-)

I also like to debate topics I know something about and/or are important, but in Audio I listen to people like you and others hash it out and try to use Reason to differentiate where the truth lies because I don't have the technical background--the proverbial Grasshopper, if posting in another thread. biggrin.gif

Fwiw, I agree with you on not liking the response "You always have to be right," by those that miss the point or are flat out wrong....We suffered that the other day when after hours of giving conscientious responses I woke up the next morning only to find the dude felt he "won the battle" and was still giving parting shots and I felt the need to vent and still trying to be civil, did so---His response was filled with so much misinformation but ended with "you always have to be right," and I thought 'No, I hate being wrong so I learn as much as I can' (but will freely admit when I am) and only post when thinking I can be helpful....

That said, I don't own the thread starters speakers and apologize to those that like to stay on topic. smile.gif Morning coffee, dontcha know.
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post #638 of 651 Old 04-21-2014, 02:28 PM
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Good point. Go really big and it doesn't take much power at all.

Speaker design has changed since 1980. In the past horn loaded or corner loaded high efficiency speakers were needed because of the low power amps available back then. A 15 watt tube amp may have been all you had to work with.

And placing the midrange driver in the same baffle that was needed to accommodate the sub driver is a compromise that designers now would rather avoid because of baffle bounce.


If you look at more modern designs you may notice a lot of speaker builders go to a lot of trouble to reduce the baffle area around the midrange drivers.
i.e.. even the examples I posted the other day...





Narrow speakers isn't just a trend for fashion reasons. The importance of this trend is reducing baffle area surrounding the midrange drivers.

And doing so is also reducing cabinet volume for the sub drivers. But this isn't such a problem anymore as high powered amps are readily and cheaply available. Speaker designers are capitalising on today's high powered amps and are able to build speakers with smaller baffle area.

Whether a sub driver has an integrated 1000 watt amp or an external active digital crossover with an external 1000 watt amp is irrelevant. It's the same thing.

And nobody yet has mentioned what speakers Gene at Audioholics was actually using so I take that as nobody actually knew what speakers they were before they started making fun of him...???
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post #639 of 651 Old 04-21-2014, 04:51 PM
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Originally Posted by kiwi2 View Post

Speaker design has changed since 1980. In the past horn loaded or corner loaded high efficiency speakers were needed because of the low power amps available back then. A 15 watt tube amp may have been all you had to work with.
And you get thermal compression with every driver, so inefficiency due to small volume speakers is not your friend either.
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Narrow speakers isn't just a trend for fashion reasons. The importance of this trend is reducing baffle area surrounding the midrange drivers.
Incorrect. Baffle width simply needs to be factored into the design and wide baffle speakers actually have an advantage compared to narrow ones because of the difference in radiation impedance between 2pi and 4pi space. Narrow speakers look smaller and are therefore an easier sell.

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post #640 of 651 Old 04-22-2014, 05:33 AM
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Originally Posted by kiwi2 View Post

Speaker design has changed since 1980. In the past horn loaded or corner loaded high efficiency speakers were needed because of the low power amps available back then. A 15 watt tube amp may have been all you had to work with.
And you get thermal compression with every driver, so inefficiency due to small volume speakers is not your friend either.

The days when 15 WPC was relevant to good quality audio systems were pretty well ended in the 1950s. The 1960s were the heyday of tubes and even economical stereo receivers were up in the 25-35 watt range with fairly economical separate power amplifiers like the Dyna Mark series putting out 40-60 wpc. In the late 1960s SS amplifiers became clean enough and reliable enough to be suitable for mainstream use and 60 wpc became the new median. By the mid-1970s amps with power levels in the 150-200 wpc (8 ohms) and appreciably more into 4 ohms became popular. By the 1980s 400 watts or more were economical to obtain.
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Narrow speakers isn't just a trend for fashion reasons. The importance of this trend is reducing baffle area surrounding the midrange drivers.

Incorrect. Baffle width simply needs to be factored into the design and wide baffle speakers actually have an advantage compared to narrow ones because of the difference in radiation impedance between 2pi and 4pi space. Narrow speakers look smaller and are therefore an easier sell.

Agreed. It is true that narrow baffles can give a boost in the lower midrange, but its been decades since speaker designers were solely dependent on acoustics in order to obtain smooth response. The same thing can be done in a passive or better yet active crossover.
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post #641 of 651 Old 04-22-2014, 01:49 PM
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Incorrect.

Aren't you confusing baffle step with baffle bounce? Yes a wider baffle can boost the upper bass range, but baffle bounce is another consideration on top of that.

We all know as frequencies get lower that the sound waves want to travel in every direction and wraps around behind the speaker. A midrange driver placed on a large flat baffle will put out the sound directly from the driver itself but you'll also get a delayed sound from the sound waves that are travelling across the baffle face as well. This is believed to reduce detail and soundstageing.

Many speaker designs do work towards minimising baffle area surrounding the midrange driver.



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post #642 of 651 Old 04-22-2014, 03:03 PM
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Originally Posted by arnyk View Post

The days when 15 WPC was relevant to good quality audio systems were pretty well ended in the 1950s. The 1960s were the heyday of tubes and even economical stereo receivers were up in the 25-35 watt range with fairly economical separate power amplifiers like the Dyna Mark series putting out 40-60 wpc. In the late 1960s SS amplifiers became clean enough and reliable enough to be suitable for mainstream use and 60 wpc became the new median. By the mid-1970s amps with power levels in the 150-200 wpc (8 ohms) and appreciably more into 4 ohms became popular. By the 1980s 400 watts or more were economical to obtain.
I'm not seeing the relevance of that comment; I'm well aware of the history of amplification. After all, I've been designing them since I was a teen.. Compression in the driver is due to the VC being heated, Re increasing and the efficiency being reduced.


Quote:
Originally Posted by kiwi2 View Post

Aren't you confusing baffle step with baffle bounce? Yes a wider baffle can boost the upper bass range, but baffle bounce is another consideration on top of that.

We all know as frequencies get lower that the sound waves want to travel in every direction and wraps around behind the speaker. A midrange driver placed on a large flat baffle will put out the sound directly from the driver itself but you'll also get a delayed sound from the sound waves that are travelling across the baffle face as well. This is believed to reduce detail and soundstageing.

Many speaker designs do work towards minimising baffle area surrounding the midrange driver.



I'm well aware of what diffraction is, it's causes and effects. Acousticians have been installing speakers in studios in soffits for decades to effectively make the baffle width the same as the wall. If you make the baffle narrow to make it saleable, then you have little choice but to reduce the width as much as possible, or make the distances to the baffle edges as variable as possible a la Avalon.
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post #643 of 651 Old 04-22-2014, 04:10 PM
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I'm well aware of what diffraction is, it's causes and effects. Acousticians have been installing speakers in studios in soffits for decades to effectively make the baffle width the same as the wall. If you make the baffle narrow to make it saleable, then you have little choice but to reduce the width as much as possible, or make the distances to the baffle edges as variable as possible a la Avalon.

You now seem to be confusing edge diffraction with baffle bounce. Baffle bounce is the sound waves travelling across any flat front baffle surface before they reach the sides of the speaker cabinet and begin to roll around and cause diffraction. This is why infinite baffles (as in in-walls) do not have 'edge diffraction' but will still have 'baffle bounce'.
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post #644 of 651 Old 04-22-2014, 04:19 PM
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Originally Posted by arnyk View Post

The days when 15 WPC was relevant to good quality audio systems were pretty well ended in the 1950s. The 1960s were the heyday of tubes and even economical stereo receivers were up in the 25-35 watt range with fairly economical separate power amplifiers like the Dyna Mark series putting out 40-60 wpc. In the late 1960s SS amplifiers became clean enough and reliable enough to be suitable for mainstream use and 60 wpc became the new median. By the mid-1970s amps with power levels in the 150-200 wpc (8 ohms) and appreciably more into 4 ohms became popular. By the 1980s 400 watts or more were economical to obtain.
I'm not seeing the relevance of that comment; I'm well aware of the history of amplification. After all, I've been designing them since I was a teen.. Compression in the driver is due to the VC being heated, Re increasing and the efficiency being reduced.

Sorry about the way I quoted the post. You aren't the author of the part of the post that I targeted. I was targeting the post that you responded to.

But since we are on the topic of compression...

Agreed that heating of voice coils is a major cause of thermal compression.

However, voice coil construction tends to scale with the power levels that the driver is designed to handle. The actual temperature rise in a more efficient driver may be more or less than the temperature rise in an otherwise comparable but less efficient driver.

For example, a less efficient tweeter designed to operate at higher power levels may include ferrofluid to help dissipate heat and actually have less temperature rise at the same SPL.

Generalities are inherently more susceptible to being questioned.
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post #645 of 651 Old 04-22-2014, 04:29 PM
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Agreed that heating of voice coils is a major cause of thermal compression.

However, voice coil construction tends to scale with the power levels that the driver is designed to handle. The actual temperature rise in a more efficient driver may be more or less than the temperature rise in an otherwise comparable but less efficient driver.

For example, a less efficient tweeter designed to operate at higher power levels may include ferrofluid to help dissipate heat and actually have less temperature rise at the same SPL.

Generalities are inherently more susceptible to being questioned.
No argument there. The graph I posted comes from the datasheet of a Beyma 6MI90, a design that has no special cooling features included. I used it as I had it easily to hand and because it has no cooling incorporated is fairly representative of audiophile drivers. Pro drivers, as I'm sure you're aware because of their higher thermal rating and generally higher applied power (and for extended durations) do facor in the need for cooling. Parnham and bossobass have specifically included cooling via heatsinks and fan cooling respectively.
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post #646 of 651 Old 04-22-2014, 04:32 PM
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You now seem to be confusing edge diffraction with baffle bounce. Baffle bounce is the sound waves travelling across any flat front baffle surface before they reach the sides of the speaker cabinet and begin to roll around and cause diffraction. This is why infinite baffles (as in in-walls) do not have 'edge diffraction' but will still have 'baffle bounce'.
The only reference to baffle bounce I could find (I've never heard the term before) was in some Newform marketing gibberish. Could you please provide an engineering reference as your own description I quoted is describing diffraction.
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The only reference to baffle bounce I could find (I've never heard the term before) was in some Newform marketing gibberish. Could you please provide an engineering reference as your own description I quoted is describing diffraction.

And that's where he got the term from. See post #7 in this thread:

http://www.avsforum.com/t/1497971/speaker-designs-that-add-height-to-the-image-soundstage-compared-to-normal-single-midrange-drivers

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^ biggrin.gif
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post #649 of 651 Old 04-22-2014, 05:20 PM
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I see.
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post #650 of 651 Old 04-23-2014, 12:15 AM
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Originally Posted by A9X-308 View Post

The only reference to baffle bounce I could find (I've never heard the term before) was in some Newform marketing gibberish. Could you please provide an engineering reference as your own description I quoted is describing diffraction.

I see it also gets referred to as baffle reflection...

"Almost all conventional loudspeakers are plagued by the following two acoustical problems: (1) reflection of the acoustical output from the transducers off of the front surface or baffle area of the loudspeaker cabinet; and (2) diffraction of the acoustical output from the transducers off of the edges that form the perimeter of the baffle portion of the loudspeaker cabinet"

www.patentstorm.us/patents/5731555/description.html

As most of us know it's the mid and lower frequencies that want to curve around behind the speaker.



By the time you get to the crossover frequency for the tweeter the sound energy is practically beaming forward so baffle reflection/bounce isn't such a problem. A tweeter can sit in a large baffle happily enough.

And as most speakers now are only just wide enough for the low frequency drivers, baffle bounce isn't such an issue there either.

However the midrange driver is still susceptible to the problem if sitting in a baffle size that was wide enough for the larger low range drivers. This is why you see some designs going to the trouble of reducing baffle size for the midrange driver.

I had seen a good image of modelling of the sound energy travelling across a baffle face recently on some white paper. I will see if I can find it again.
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post #651 of 651 Old 04-23-2014, 08:46 AM
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Quote:
Originally Posted by A9X-308 View Post

The only reference to baffle bounce I could find (I've never heard the term before) was in some Newform marketing gibberish. Could you please provide an engineering reference as your own description I quoted is describing diffraction.

I see it also gets referred to as baffle reflection...

"Almost all conventional loudspeakers are plagued by the following two acoustical problems: (1) reflection of the acoustical output from the transducers off of the front surface or baffle area of the loudspeaker cabinet; and (2) diffraction of the acoustical output from the transducers off of the edges that form the perimeter of the baffle portion of the loudspeaker cabinet"

www.patentstorm.us/patents/5731555/description.html

As most of us know it's the mid and lower frequencies that want to curve around behind the speaker.



By the time you get to the crossover frequency for the tweeter the sound energy is practically beaming forward so baffle reflection/bounce isn't such a problem. A tweeter can sit in a large baffle happily enough.

And as most speakers now are only just wide enough for the low frequency drivers, baffle bounce isn't such an issue there either.

However the midrange driver is still susceptible to the problem if sitting in a baffle size that was wide enough for the larger low range drivers. This is why you see some designs going to the trouble of reducing baffle size for the midrange driver.

I had seen a good image of modelling of the sound energy travelling across a baffle face recently on some white paper. I will see if I can find it again.

The above polar pattern is IME a problem waiting to happen.

Better results can be obtained, such as this:

http://www.avsforum.com/t/1224991/what-does-jim-holtz-mini-statements-speakers-compare-to-commercially/60#post_20265519

http://www.musicanddesign.com//naomain.html

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