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Multi-Way Conventional loudspeakers with crossovers

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Old 14th November 2013, 10:28 AM   #9751
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Hi,
In the last discussion, I'm with you, Lynn and Pooh.
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Old 14th November 2013, 02:55 PM   #9752
platan is offline platan  Greece
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Originally Posted by Lynn Olson View Post
............

I prefer to overdesign the critical 200 Hz to 5 kHz region, giving the drivers plenty of overlap room. (The drivers have useful and well-behaved response outside the system crossover.) Not everyone does this; many designers take drivers right to the limit of what they can do, and sharp-cut at that limit. Speakers that are designed that way sound "nervous" and a little unsettled to me; I prefer a "relaxed" sound from a loudspeaker...........

200 HZ -5 khz........
Example........ Lowther (95-100db)


I prefer a "relaxed" sound from a loudspeaker............
Example........... Horning Loudspeakers
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Old 14th November 2013, 04:38 PM   #9753
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There cannot really be a points or percentage rating. You can get into the A is better than B is better than C is Better than A or however this false paradigm can go.

If you take the original sound whether at a concert, in the studio, or anywhere else as the standard to achieve, you may say that ii is nearer or less near than another system. You could do this for 1000 systems say for opera recorded from previously attended venues eg. Madison Gardens or RAB in London etc. If you then say repeat this for some jazz and say drama your order of preference will probably be different.

This assumes top quality recordings without sound reinforcement at the venue. i.e all real sound.

Now if you play back at low to high levels and compare you may judge differently.

It gets more complicated if you try to be too analytical.

I am going to be tough and say CLass A only period. Oe exception may be extremely fast devices with very low switching times in nano seconds. If you cannot hear the difference then the rest of the reproduction chain has some problems or you dont have perfect hearing.

It is not just about dynamic contrast and power which is important. We know it is a matter of compromise through the whole chain of reproduction. Even the room temperature and humidity can have soime effect.

John Atkinson had it right when he sted in stereophile about hearing a guitar being play directly through its amplifier and speaker (with its limitations) it still sounded better than any recording of the same played back through a then especially esteemed system.

Everyone will have a different and interesting view on this. This is not intended to be daunting and as DIYers we are really trying to get closer to fidelity or our own personal preference.
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Old 14th November 2013, 05:21 PM   #9754
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Quote:
Originally Posted by boldname View Post

It gets more complicated if you try to be too analytical.

Everyone will have a different and interesting view on this. This is not intended to be daunting and as DIYers we are really trying to get closer to fidelity or our own personal preference.
That's why we build our own systems. For example i found only a couple of triode class A amplifiers I like to drive my multi-amped system (most are so colored they are a joke) but only in a certain range above 100 cycles. Pentodes serve their purpose too as well as class AB sand amps. There really is a benefit to having a lot of power below 100 cycles and class tube or SS A down there (250 WPC or more) isn't in my budget or game plan. Ceartainly there is a difference in AB amps driving bass horns and I'll take tight powerful control over tube roundness anyday. I do agree with Lynn stating where he likes to use wider bandwith drivers in their relaxed range. It's a no brainer once you set something up like that right and live with it for a while.
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Old 14th November 2013, 06:18 PM   #9755
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Originally Posted by Lynn Olson View Post
I don't think adding subjective numbers together tells us much; the amplifier/speaker interface determines much of the resulting sound quality, and the standard measurements do not really address interface issues that well.

Some amplifiers are more compatible with some speakers than others; this is due to settling time of the amplifier when driving reactive loads, transient output Z variations as transistors pass through the Class A/AB switching region, current pulses from +/- supply rails getting into input stages, AM radio/RFI pickup from the speaker wires, etc. etc. There are many subtle faults in amplifier design that are more readily exposed by some speakers than others.

Loudspeaker faults are grosser, and more easily measured, although there is much controversy about which measurements correlate most closely with subjective impressions.
Your design rational is conflicted system of subjective impressionism with a dash of technical merit tossed in for flavor.

Overdesign? An imaginary line of headroom drawn in to separate vague transition from linear to non linear from a sharper one.

Making decisions about amplifier choice based on comparisons with speaker designed to flop about on its own v damping that is coupled to amplifier output impedance?

Yes, there are many speaker faults readily exposed by some amplifiers and not by others.

Yes, the algebra of subjectivity is tricky. With it rules of manipulation, and definitions of objects and operators, all proofs become random collection of symbols. Each is at best an impressionist's rendering, open only to interpretation of each observer's mind.

Dr. Geddes design approach is very simple. It is based on direct radiator's transitional behavior from omnidirectional with spherical wavefront to that of planar wavefront, and on horn loaded radiator's transition from omnidirectional behavior to that of bounded projection as a sector of a spherical wavefront. Metrics for shapes of wavefront for two systems are found, and used for selections of direct radiator, horn radiator, and crossover point that is chosen. Equalization applied by crossover filters determines acoustic performance of each drive element in targeted listening field, and are generally chosen for a smooth frequency response. Design constraints based on complexity/cost of filters v performance in shaping response of drive elements are made. With design constraints defined, building and optimizing system is relatively straight forward process.

Neodymium/conductive magnets v ceramic/non-conductive magnets:

Differences are readily observed by simply dropping sample slugs of each through copper tube. Magneto restrictive damping inherent to conductive magnet is a primary consideration for employment in transducer motor. Think about dropping magnets through solenoid coil. Behavior with coil terminals shorted v open are completely different. Think of complex impedance of such coil with complex drive signal; or even with high level high frequency signal. Think about damping system across coil terminals, and notion of feedback.

Perhaps think about Barkhausen Noise Analysis. Behavior of magnetic field of magnet immersed in external magnet field; displacement of field about magnetic domains; and ability to flip or rotate magnetic domains. Hysteresis involved with repeated application and removal of external magnetic field are quite telling, and repetition with increasing external field strength reveals even more.


At some point build something and compare thoughts about how predicted and measured responses compare; see how well thought process correlates to physical process. This correlation is best improved by modifying thought process.

No speaker to amplifier interface exists other than wire. Once connected together a single system is formed. It is best described as convolution of impulse responses of each system. Absolutes are calculated through application of reciprocity principle to each degree of freedom for all elements within measurement system and system under test. Primary example: Standardization of reference microphones. Same techniques may be used for each individual systems; but results from reciprocity based reference may be used as comparative standard allowing matching methods that greatly reduce efforts required of practitioner in the field using measurement qualified microphone associated amplifier.

An artist is grounded by real behavior of physical media. Art is refinement in practiced technique with input from the imagination. Loads of room for art in speaker building, but making art requires doing the work too.
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Old 14th November 2013, 06:49 PM   #9756
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Originally Posted by Pano View Post
I took the bug screens out of my 288s. Could not hear or measure any difference. Surprising, really.
Hmmm - thanks for the info !
Which type of driver were they, Pano ?
The 288H has the extended response that goes up to 12kHz, but it's not smooth on the way up to 12k . I'll still try to give this a try if I can . Will fit the small choke this evening which should at least confirm if it's the 10k+ area that's causing the shriek .
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Old 14th November 2013, 07:17 PM   #9757
gedlee is offline gedlee  United States
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Barleywater

Building an airplane is easy as well:

- take paper and pencil
- draw airplane
- send to Boeing to build
- "optimizing system is a straightforward process"
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Old 14th November 2013, 07:29 PM   #9758
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Quote:
Originally Posted by gedlee View Post
Barleywater

Building an airplane is easy as well:

- take paper and pencil
- draw airplane
- send to Boeing to build
- "optimizing system is a straightforward process"
If you worked for Boeing then you had a head start. At least they know how to use Titanium and Beryllium
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Old 14th November 2013, 07:35 PM   #9759
badman is offline badman  United States
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Quote:
Originally Posted by Barleywater View Post
An artist is grounded by real behavior of physical media. Art is refinement in practiced technique with input from the imagination. Loads of room for art in speaker building, but making art requires doing the work too.
Nicely put. It's what's frustrating about the overly artsy types- many who have eventually become decent designers started out by tweaking, but they only get really good when they become more serious.

There are of course the opposites, engine-ears who jump all too readily to conclusions about what's important, and wind up designing systems that meet their criteria and sound bad. They need to learn the art, the artists need to learn the engineering, and large portions of either cult fail to progress beyond the half of the equation they're comfortable with.
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Old 14th November 2013, 08:52 PM   #9760
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Originally Posted by fas42 View Post
Okay, try again!!

Let's say subjectively satisfying sound can achieved with a system of quality 100 - just points, it's not a percentage.

The very best source in 'perfect' condition could be 75 points, best amplification 75, best speakers 75. Connect them together 'perfectly', you get 225 points, way, way better than you need - should have excellent sound, ! But wait, there's more!! Subtract points for interference effects, connection problems, all sorts of niggling problems - very easy to lose 150 points in a blink of an eye, no longer have 225, you're down to 75 in real terms, what the ears hear. Somehow, you have to recover 25 points to get the good sound - this can be the hard bit!

This also means that 'mediocre' gear, worth only 35 points in each category, adds up to 105 - but end system is very, very carefully tweaked so that only 5 points are lost - with cleverness and understanding it has just made the grade ... it's worth listening to.

This type of balancing is how I see the process of achieving worthy sound ...
I like that analogy
It works for me
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