Mini Karlsonator (0.53X) with Dual TC9FDs

[soundaddict]

I use a mixture of wood glue and white flour to seal enclosures...the cheapest I can go for a strong sealing bond.

 

[Skylar88]

Interesting. It can probably be called "organic glue". Reminds me of mixing micro balloons into epoxy resin to thicken it.
.
.

 

[xrk971]

Cooked mushy rice makes decent organic glue as well. Almost any complex starch with gluten can work. Good idea to use flour as thickener for PVA.

 

[hammercha]

"Cooked mushy rice makes decent organic glue as well."

Growing up this is what we used to fix the tear on the paper kites

 

[EddieT]

I was considering plaster of Paris mixed with glue to seal and smooth cracks where I extended depth of a small enclosure, now flour is another option.

 

[gaborbela]

Try to use Alex plus or bathroom silicon. Alex plus it is cheap and most of the time it works. The silicon very likely works on your surface but a bit more pricy. It will last for a long time and seals very well and good adhesive.

 

[pvsumith]

a year or two ago, Loudspeakersplus had the P-Audio 15CXA with 100oz magnet and cast frame for $99.95 including their BMD440 compression driver - that would have been a traditional Karlson K15 coax. I mentioned it several times on this forum and they finally sold out.

I managed to get hold of a pair of 15CXA and planning to go with K15, what is the recommended XO point for this driver as per your experience.

 

[xrk971]

That’s an impressive looking Coax! What does the datasheet recommend as XO point? With a 15in, I would try to go lower - can it handle 1500Hz? Typically 2500Hz is good but might be too high for a 15in to cross over to.

 

[pvsumith]

There is no spec sheet available with it but I found a crossover for the CD in their site and the XO is 2500hz with 12db slope. I am also hoping to cross it over at 1500 to avoid the 15inch cone beaming.

 

[freddi]

I've run that compression driver with Eminence generic (8uF/0.3mH/22uF) "1K6" 3rd order highpass on a K-tube without strain.

It could be run with just say a 3.3uF cap and not much padding - if any


P.Audio BMD450 - P.Audio BMD450 1" bolt on type high frequency compression driver. P.Audio speaker components available at US Speaker.

Loudpspeaker plus closed those 15cx out at $95 each - no one was interested on this forum as wanted FR.

 

[pvsumith]

Were you running the FR through and only CD was XOed using crossover?

 

[freddi]

you can try running the woofer section fullrange and tweeter with say a 3.3uF cap then compare that to a more conventional crossover.

FWIW the late Stan Ricker suggested that as a way to run Altec 604. I think that also was the way David Dicks suggested.

That may or may not sound good - but simple to try and if you don't play things at PA levels, 3.3uF should not pass enough LF energy to hurt the driver. (it can and will interact with a driver/horn's input impedance - usually to give a lower cutoff than what would happen if the driver was a pure resistive load)

With a small value capacitor as the only highpass element to the compression driver and no padding, the result will result in proportionately more energy at the top octave than a lower cutoff steeper slope highpass with no contouring,. In other words, a "brighter" more extended sound,

There should be measurements and crossover schematics for your 15CXA.

One would not want any baffle step compensation with K15.

For fun you might consider a battery biased charge -coupled highpass filter and paper in oil
capacitors such as MBGO vintage Russian type. Remember that two series capacitors need to be 2X the value so two 6.8 uF capacitors with 1Meg resistor and a 9VDC battery would work.

You should post questions in the Multi-Way forum as to what crossover scheme might work best and also what 'might
give the best time alignment. FWIW I tried an LC LC Allpass filter after the lowpass on my woofer - dunno if was optimal
but the sound seemed more cohesive.

This is what I used on the woofer. IIRC the late DJK may have suggested to try 0.25mH (?)

The goal is to try the shift the woofer's acoustic center closer to that of the tweeter.

 

[pvsumith]

Thanks Freddi for that detailed information, I will start procuring the parts and update how things are moving. I will probably start with 3.3uf first order with HF and the all pass at LF.. can add an Low pass later if needed.
Cheers

 

[pvsumith]

you can try running the woofer section fullrange and tweeter with say a 3.3uF cap then compare that to a more conventional crossover.

FWIW the late Stan Ricker suggested that as a way to run Altec 604. I think that also was the way David Dicks suggested.

That may or may not sound good - but simple to try and if you don't play things at PA levels, 3.3uF should not pass enough LF energy to hurt the driver. (it can and will interact with a driver/horn's input impedance - usually to give a lower cutoff than what would happen if the driver was a pure resistive load)

With a small value capacitor as the only highpass element to the compression driver and no padding, the result will result in proportionately more energy at the top octave than a lower cutoff steeper slope highpass with no contouring,. In other words, a "brighter" more extended sound,

There should be measurements and crossover schematics for your 15CXA.

One would not want any baffle step compensation with K15.

Which design is recommended for this driver, the original Karlson 15 or any other modern iterations. I could see many designs with different slot designs hence confused. I am eyeing for mid purity, LF extension is not my primary goal, anything around 40s would be good enough.

 

[freddi]

K15 is certainly appropriate. XRK971 might look into other possibilities using Akabak and your driver's spec. K15 should pretty much maximize "punch". A 1.2X scaled Acoustic Control 115BK would be about the same bulk as K15 and tune a few Hertz lower. A 15 inch Karlsonator simply scaled might tune too low so should be adjusted so Fb no lower than 40Hz.

BTW, When asking X for an Akabak simulation, arrange your driver's specs like this to save him time of typing, etc.


Def_Driver ‘6PEV13’ | B&C 6 inch midrange driver 2.5mm xmax
Sd=132cm2
fs=126Hz
Mms=6.0g
Qms=4.6
Qes=0.39
Re=5.2ohm
Le=0.60mH
Vas=6.0L



I think Les Hudson used your model of coax when he built K15 (and scaled K15) - it also could have been the heavier model (?)

The "Blue Monster" /BM frame color is nice - my P-Audio have black frame

 

[pvsumith]

I would try the K15, don't want to bug XRK with the published TS as I heard those are very "optimistic". Now I need to figure out which port design will work the best for this.

Below are the T/S values, but no info about Mms.

Resonant Frequency (Fs) 39 Hz
Impedance (Re) 5.6 ohms
Mechanical Q (Qms) 6.45
Electrical Factor(Qes) .25
Total Q (Qts) .24
Comp. Equivelant Vol. (Vas)
9.09 ft3 / 257.5 Liters
Voice Coil Overhang (Xmax) 2.75 mm
Surface Area of Cone (Sd) .083 m2
BL Factor (BL) 18.45 T-M

 

[EddieT]

Freddi, what were those bottom cabs on the far L&R in the Les Hudson home theater pic?

 

[Jazzfan]

Back loaded horn.

 

[freddi]

yeah - Hedlund style BLH

Here's another view of that cabinet - IIRC (?) Les's dog's name was "Jim"

 

[EddieT]

Thanks, my eyes were playing tricks on me, I thought I saw separate tops and bottom.