Sensitive Wide Range Open Baffles

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#103
not sure why the ripple - they were both without rear chamber

I may have had 1/8" spacer in those graphs but don't remember for sure - gap should be pretty easy to tune outdoors with RTA. That Alpha 6A/conical combo had wild impedance interaction with 1st order filter - guess back chamber, or LC conjugate or odd order would fix.

hope U get the K-tubes and have some fun
 
#105
A couple of things have me puzzled in the current set up.

Maybe you can help me understand what's up?

1) You're getting 104dB in the low end? Would that be 104dB at 2.83 volts, or about 2.5 watts, right? Very surprised to hear that you don't use EQ on the 10s. What do you figure the baffle roll-off point is? Must be pretty low not to need EQ. Is the room helping?

2) The midrange waveguide. It looks like the mouth is about 12". Can it really play well down to 300Hz? A normal horn that size wouldn't, is the low cutoff due to it being a waveguide, not horn? How much does the waveguide boost the sensitivity of the B&C driver?

The system concept seems really cool. I'd like to learn more about how it works. Thanks.
 
#106
panomaniac said:
A couple of things have me puzzled in the current set up.

Maybe you can help me understand what's up?


1) You're getting 104dB in the low end? Would that be 104dB at 2.83 volts, or about 2.5 watts, right? Very surprised to hear that you don't use EQ on the 10s. What do you figure the baffle roll-off point is? Must be pretty low not to need EQ. Is the room helping?

2) The midrange waveguide. It looks like the mouth is about 12". [Can it really play well down to 300Hz? A normal horn that size wouldn't, is the low cutoff due to it being a waveguide, not horn? How much does the waveguide boost the sensitivity of the B&C driver?

The system concept seems really cool. I'd like to learn more about how it works. Thanks.
Click to expand...

Yes, the voltage sensitivity is that high, it's a 2.3 ohm load, five 10's (rated at 99 db sensitivity but actually 93 each) - the room adds a lot, they are usable to 45 cycles but I high pass them for several reasons. The baffle doesn't seem to rolloff in a traditional sense, it is 24" wide, with a high QTS driver that doesn't mean much (seeMartin Kings latest OB stuff) when used in the room. The fact the 5 drivers combine in output in the low frequencies take that further, so does the reflection in the floor and side walls.

This calculator works, but does not account for the gain of the parallel wired array, so it's calculated 103.8 db is in reality higher


The horn a is usable below 300 HZ (ie look at freddi's response from his 300 flare horn) but is unloading. Cones tend to peak at the flare rate in midrange horns. I believe it's best to crossover above that point (or try to eliminate the peak like Edgar did with spacers in his cone driven mid horn). A normal horn will peak with this driver. The gain is not linear and neither is the driver out of the horn, that is why you shouldn't use a linear driver in horn. What you are looking to do is end up with a more efficient coupling to the air and a linear response over as wide of bandwidth as you require. I want to use the mid out to 4-6K that's why I am going to try the JBL driver, the B&C doesn't make it there. A rising response driver is mandatory. In this case below 1K there is around 6-9 db gain and only 5-3 db gain in efficiency (less as the freq goes up) to 3K, then the response drops off. This caused by mass loading and not enough motor.


Power to drive horns.
 
#108
Many thanks for your participation in the "other" thread, Magnetar. Your real-life experience with high-dynamic systems is much appreciated, at least over here in Northern Colorado.

I'm probably travelling along a parallel path - I like what the audiophile system do well (low coloration etc.) - but just can't accept their dynamic limitations any longer. I couldn't agree more that the claims of "high SPL" from the audiophile exotics are nothing short of absurd. The direct-radiator exotics I've heard - including the Feastrex - pretty much started to fall apart around 95~100 dB SPL, which limits them to "audiophile" musical selections.

I'll be seeing you over here from now on, and thanks again for insightful postings you've made.
 
#111
Lynn Olson said:
Many thanks for your participation in the "other" thread, Magnetar. Your real-life experience with high-dynamic systems is much appreciated, at least over here in Northern Colorado.

I'm probably travelling along a parallel path - I like what the audiophile system do well (low coloration etc.) - but just can't accept their dynamic limitations any longer. I couldn't agree more that the claims of "high SPL" from the audiophile exotics are nothing short of absurd. The direct-radiator exotics I've heard - including the Feastrex - pretty much started to fall apart around 95~100 dB SPL, which limits them to "audiophile" musical selections.

I'll be seeing you over here from now on, and thanks again for insightful postings you've made.
Click to expand...

Thanks, your welcome, see you and good luck with your new speakers


Illusus said:
I've been tumbling down the same hole ever since I built Karlsons. Just can't get enough slam.
Click to expand...

I think freddi has a point!


freddi said:
2-K15 per side would probably have pretty good impact - - I still like K15 with coaxial on cello and bowed double bass
Click to expand...

How about a wall of K's? !!


🙂
 
#113
Hi Mike

A quick one

I'm so seduced by your idea of 4 audax 170+ compression driver that I bought 8 max fidelity pr65neo (170 on steroid) and I'll do a TMMMM +2subs (rythmik audio)

I'm settled to buy the BC DE250 compression driver instead of your de10 cause it appeal me more.

The only thing is I don't know if I should buy the 16ohm version of the compression driver.
I'm using SS amp now but might do a move to OTL amp.

Is there more drawback with the 16ohm version (heavier voice coil because of more winding, more inductance rise at hf)


Thanks
 
#114
Lynn Olson said:


The visual similarity of the RAAL to other similar-looking drivers is deceiving. I cornered Alexander on just this point - what's going on here, anyway?

His story is that electrostats, magnetic stretched-films, and corrugated ribbons all share a common defect - the diaphragm goes into thousands of chaotic drumhead modes, and most of the kinetic energy is dissipated into self-excitation, instead of into the air. In effect, the air load supplies much less large-area damping than conventionally thought - the smoothness of the response is actually thousands of fine-grained modes, which can be measured when the microphone is a half-inch away from the diaphragm.

The "uniform surface drive" design expectation for all three classes of drivers only occurs at the lowest frequencies - above that chaotic drumhead resonances dominate and give a fine-grained roughness to the response, as well as robbing dynamics of their impact. It is equivalent to "current-hogging" in an array of transistors, where a few transistors do all the work and the rest are all idle. In planar, stretched-film, and conventional ribbons, only a few areas actually radiate sound in a coherent way, the rest is going into chaotic modes that are strongly level and frequency-dependent.

The trick on a planar driver of any sort is to distribute these drumhead modes in a controlled way, and shape the magnetic field so skin effect (a big problem with the very thin flat ribbon in a ribbon tweeter) doesn't distort the current flow in the ribbon. Solving these problems is non-trivial and requires access to laser holography labs.

Is this theory-of-operation true? I have no way of knowing without looking at the data for myself - this is the kind of thing I'm reluctant to accept on faith, or even a persuasive argument. Whether Alexander's hypothesis is valid or not I cannot say - but they do sound different than any ribbon I've heard so far, which is something I didn't expect at all.
Click to expand...

Lynn, can you point us to further discussions of this theory of 'chaotic drumhead modes,' particularly as it applies to ESLs? Mostly because I don't *want* it to be true about my beloved ESLs...
 
#115
DONE

The setup is pretty much as far as I plan to take it!

Five 16 ohm 10" warrior woofers in parallel, high passed 18db per octave at 70 cycle (50 cycles -3db point due to 'bump')

Horn loaded sub low passed at 40 cycles - JBL 2242H

B&C 6" midrange loaded in 360 flare round tractrix horn crossed at 350 4th order - low passed at 3K 4th order (this makes the JBL LE5/2 - 2105 sound like the toy it is)

B&C DE10 'non-metallic' 1" compression driver in the Transylvania K-Tube - 3K up - Freddi - I need to copy this tube - It is AWESOME!!!

This is quad-amped, no contour passive or active needed. Crossover - Marchand with 4562 opamps, teflon caps, no metallic resistors- amps tube except bottom end

Tone is awesome, dynamics killer, imagining same - the bass kicks the crap out of the four 21" woofers I used in the WMTMW open baffle system.

No more 'hi-end' headphone sound, more live and natural - almost as live as a 5 way way horn system with better tone and imaging in a lot less space. A very decent compromise IMO
 
#116
hi Mike - -I built my straight tube a long time ago and without seeing Transylvania's "The Tube" which has a 2 degree downwards taper and somewhat different taper.

I suggested k-tubes (done carefully) for 7 years almost every week or so at AA HE and no-one bit. IMO Walter Zintz did a nice job on that one.

if you make a straight 5.3" long 1"ID tube with half-ellipse slot and ~1/8" starting gap at the beginning then you can compare and hear if it works as well - -I've not compared side by side.

CN used APT50 with the tubes mounting APT3 to a half inch plywood plate and removed APT3's excess.

spread the good Karlson word - its hard to beat for a 10 cent waveguide and like it better on harpsichord and cymbals than pro 90

Freddy

approximate pattern for straight version
An externally hosted image should be here but it was not working when we last tested it.
 
#117
Seems like it would be easy enough to make one of the slot tubes. Maybe the DIY guys will start building them, unlike those on other forums...

3K up a good working range?


Magnetar, congrats on the new system. Seems like you're pretty impressed with. Nice that is uses parts that are all reasonable in size and price - for a big system.
 
#118
Magnetar,

You have some experience with compression driver I wonder whether you can give me your opinion on the following models I am looking at:

Selenium DT210 and 18 Sound horn XT120, I am looking at crossing at 2khz and above.

If you are not familar with above you may like to recommend a few besides B&C DE10 which I think you like. Are there any others?

also what types to avoid.

thanks.
 
#119
ttan98 said:
Magnetar,

You have some experience with compression driver I wonder whether you can give me your opinion on the following models I am looking at:

Selenium DT210 and 18 Sound horn XT120, I am looking at crossing at 2khz and above.

If you are not familar with above you may like to recommend a few besides B&C DE10 which I think you like. Are there any others?

also what types to avoid.

thanks.
Click to expand...

Hello, I try and avoid titanium drivers like this. They tend to sound metallic and raspy. Aluminum is better but phenolic, polyester or mylar is better yet.

Other than the B&C I can recommend the TAD 2001 (expensive) or the Emilar EC175 (out of production / business) or any of the Radians. The 18 sound horns are very good! Maybe they have an inexpensive non-metallic diaphragm compression driver for them? The little BMS drivers are probably less collered than the Selenium because they are polyester.. The Beyma CP380 is VERY good

If you crossover a little higher the DE10 is a super nice driver for little money.
 
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