Does anyone else think compression drivers sound bad?

[phase_accurate]

[QUOTEYes, flux density referring to the internal field....... high magnetizing field intensity (a bad combination).][/QUOTE]

I can't follow you here. Flux density is the product of field strength H and permeability. So B is proportional to H. And I don't see where your electric field is coming from. We have electric current in a conductor (voice coil) where the difference in potential between both ends of the conductor in the magnetic gap is benign and therefore negligible.

High efficiency systems DO have high control over cone motion but sometimes at the cost of reduced output at their fundamental resonance.



When it comes to the advantages of field-coil drivers I can see two points:
The magnetic path is electrically conductive and therefore resists against shifting of field lines as a function of the forces involved which in turn reduces Barkhausen noise and nonlinear distortion. A property that it shares with Alnico magnets. The second advantage it does also share with Alnico but it can go much farther: The magnetic path can be driven into very high saturation which makes it very "stiff" and therefore further helps reducing nonlinear distortion.

Regards

Charles

[Flaesh]

Originally Posted by N101N

In the end personal preference is the only thing that matters, should weigh more than cold facts. There is no point in being dishonest with ourselves.

Individual preferences exist and cold facts exist too. [If we discard the assumption of mystical properties] One may individually prefer certain facts; he may know them, want to know them, not want to know them, or even fantasize non-existent facts that he likes .

[mark100]

Originally Posted by hottattoo

IMHO you must have a mid bass horn, that is high sensitivity, that closely matches the other drivers. This is where most horn systems fall flat. This is why I used 2 Altec 515b's in parallel. If you have to pad down all of your compression drivers to match your mid bass horn / box speaker, IT IS A TOTAL WASTE OF POWER and sucks the life out of the compression drivers by adding all the additional passive crossover parts !!! This doesn't mean you can't get good sound but you will not get the speakers full sound potential. Adding active crossovers, amplifiers, cables, DEQX, etc. makes things worse--I have tried. A simple, high quality, 6db crossover sounds the best--IN MY SYSTEM--with the drivers I use !!! YMMV.

Time alignment: All the drivers voice coils are in line within 1/8", with the exception of the subwoofers.

Hope this information helps some of the compression driver / horn lovers here !!!

Best regards,
Joe

Hi Joe, thanks for sharing experiences.

My experiences with compression drivers although similar in achieving the excellent sound we desire, run a bit different with respect to implementation.

I've had great success with CD/horn combos used with both direct radiator mids and bass, and horn loaded mids and bass. Whether my system is all horn loaded top to bottom, or a hybrid, doesn't seem to matter. What does seem to matter is the degree of tuning excellence brought to whatever the setup.

All of my various CD/horn builds have been 4-way, and active 4-channel multi-amps.
Whether i need to attenuate the CD or not is a non issue.
There's no need to match sensitivity/efficiency between the 4 driver sections, other than for max spl and headroom.
Any attenuation is done in the floating point digital domain with sufficient resolution to ensure there are no gain structure/snr issues.

I can easily see however, that with passive xovers it's more important to match the multiple sections' acoustic outputs to keep from wasting power, as of course the driver sections have to padded down to the section with the lowest output. I guess the wasted power issue is also more acute when using a single amp to drive more sections.

Along with muti-amping, I use dsp for timings, with FIR implementations handling both linear phase xovers and minimum phase EQ's.
The digital timing allows the various sections' mouths to be physically aligned in the same vertical plane, and avoids the diffraction issues from having to stagger horn mouths in order to keep voice coils physically aligned. No horns playing over or around each other.
The use of FIR, imho, brings many advantages i won't dive into, other than to say linear phase xovers are an absolute joy to use....whatever the order.

I see you mention having used DEQX. I've been surprised by how many reports I've heard from users who were less than convinced with what they achieved with it.
That always puzzled me until i read the manual.
I think it would take quite a bit time and experience using it, to follow their implementation process to full fruition.
(It's my major issue with most products that introduce digital tuning, especially FIR file software generators.....they are too dang complicated to promote rather guaranteed success. but i digress....)

I feel blessed to have learned the manual implementation of FIR via rephase..... before moving on to more automated methods or structured processes.
Ime, the automated methods and structured process can easily do more harm than good, until their capabilities or lack of, are fully understood....(something I'm continually learning).

DEQX is a case in point...when you dissect its specs, it really doesn't have that much processing capability to implement its various filters .
Please don't get me wrong, they are great units, but I don't think they are fully capable of demonstrating what dsp using FIR implementations can do for SQ. just my 2c, fwiw...

[hottattoo]

I have to say that I am very much much impressed with the knowledge of some of the people who post here. This is what DIY is all about, people looking to pick an off the shelf item to use and enjoy and the people who can explain how and why these products work. Where would we be without the work and research of Harry Olsen, Ed Wente, Don Keele, Dr. Geddes, Dr. Bruce Edgar and many others. A "simple" thing like a compression driver, horns, waveguides turns out NOT to be so simple. I enjoy and learn every time I look at this topic. Many thanks to all those who post here !!!

The topic of "high resolution" has come up several times and is also somewhat complicated. I will try to explain my observations with my particular speaker system. Most of us know how the brain interprets sound is very complicated and still not fully understood so sound quality can be subjective on an individual basis.

Some posters here have noted that I use 3 drivers to cover 450hz. to 20k+. I could have easily done this with 2 drivers and have done so.. The 3 driver approach sounds much better, I believe, do to less driver stress. All of the drivers I use have powerful motors, beryllium diaphragms and are very efficient. There is one other parameter, diaphragm resonances, and where they fall at various frequencies. It is my contention that these spurious resonances will get in the way of perceived resolution. Beryllium pushes these resonances further up in frequency then aluminum or titanium thus making them less audible. Just my take.

Truextent Beryllium for Audio Domes, Cones and Assemblies

Joe

[bradleypnw]

Originally Posted by camplo

Higher directivity will still lower the energy of the other reflections...higher amounts of direct energy equates to clarity.

Use the ripple tank simulator. Add a horn. Then wrap a small box around the horn, because that's your room relative to long low frequency wavelengths.

Ripple Tank Simulation

[GM]

Originally Posted by hottattoo

Some posters here have noted that I use 3 drivers to cover 450hz. to 20k+. I could have easily done this with 2 drivers and have done so.. The 3 driver approach sounds much better, I believe, do to less driver stress.

Works for me; horns are decade [5 octave] reproducers at best, so at ~5.6 octaves based a typical 22 kHz upper limit, it ideally needs to be divided up based on even acoustic power distribution, especially since actual horn/box loading peters out at its effective upper mass corner, but normally stuck with whatever driver/horn combos is available.

GM

[GM]

Originally Posted by bradleypnw

Use the ripple tank simulator.

For sure the room dominates, so truncated horns loading just enough to couple to the HF suffices, or in many cases, just use [multiple] H.E. [horn] drivers in a sealed or damped vented alignment depending on the desired efficiency/cutoff point.

GM

[camplo]

Originally Posted by bradleypnw

Use the ripple tank simulator. Add a horn. Then wrap a small box around the horn, because that's your room relative to long low frequency wavelengths.

Ripple Tank Simulation

Omg thank you so much! someone posted this ripple simulator in my thread earlier this year and I haven't been able to find it buried within the pages...oh you one.

[N101N]

camplo,
most importantly, for low distortion, in any electrical interface (boundary conditions), the pressure difference must be small.

phase_accurate,

I can't follow you here. Flux density is the product of field strength H and permeability. So B is proportional to H.

The quality aspects are not evident from that relationship. Higher magnetic intensity exacerbates the diseases mercilessly plaguing magnetism, such as random polarizations, misaligned magnetic moments, transitions at near resonance, saturation, hysteresis.

And I don't see where your electric field is coming from.

Magnetic fields cannot exist without electric fields and they cannot control themselves, it is done by electric fields presenting an opposing resistive force.

Electromagnetism is everywhere. It is also a prerequisite for life.

We have electric current in a conductor (voice coil) where the difference in potential between both ends of the conductor in the magnetic gap is benign and therefore negligible. High efficiency systems DO have high control over cone motion but sometimes at the cost of reduced output at their fundamental resonance.

All this is incorrect.

¤

You won`t be able to show that higher energy implies lower distortion, which should defy common sense in the first place (but it does not).