All around best 8-ohm substitute for K-33?

[Tom Mobley]

For use in a dual driver Cornwall type design? Is one of the

Eminence drivers similar in characteristics but 8 ohm instead of

4? Maybe there's a JBL out there?

In fact, I've seen a couple different takes on the T/S numbers for the

K-33. Is there substantial agreement on which numbers are best?

[DrWho]

All the T/S parameters yield very similar results (within +- 1dB) so

nothing to worry about. Real life variations will be far greater.

I am a particular fan of the Eminence Magnum 15" LF. It has 3dB less

sensitivity but will give you an F3 of 31Hz versus 38Hz and have the

same max acoustical output (right around 120dB). The Magnum should also

behave slightly better above 500Hz with about the same dispersion

pattern as the K-33. (These numbers are derived using an 8 cubic foot

volume, which yields a flatter response than the stock cornwall).

I've never actually heard the magnum, but it certainly models up very

very nicely. So I would expect real life results to be favorable, but

alas there is nothing better than actually hearing one.

If space is a concern, the magnum can fit in a smaller cabinet than the

K-33 and still get the same frequency response. In fact, the cornwall

has a cabinet volume of 6.2 cubic feet tuned to 47Hz. The magnum

achieves the exact same slope in a 4 cubic foot box tuned to 45Hz. When

going with a dual driver system....that means 8 cubic feet for the

magnum versus 12.4 for the K-33. This means you could go with 3 magnums

in the same space as 2 K-33's!

[Tom Mobley]

from the eminence site:

{EDIT} I reformatted this three times, but the BBS software keeps moving the right column up or down one line. Dang.

Nominal Basket

Diameter

Impedance

Power

Rating

Resonance

Usable Frequency Range

Sensitivity

Magnet Weight

Gap Height

Voice Coil Diameter

Mounting Information

Recommended Enclosure Volume

Volume Displaced by Driver

Overall Diameter

Baffle Hole Diameter

Front Sealing Gasket

Rear Sealing Gasket

Mounting Holes Diameter

Mounting Holes B.C.D.

Depth

Shipping Weight

Thiele-Small Parameters

Resonant Frequency (fs)

Impedance (Re)

Coil Inductance (Le)

Electromagnetic Q (Qes)

Mechanical Q (Qms)

Total Q (Qts)

Compliance Equivalent Volume (Vas)

Peak Diaphragm Displacement Volume (Vd)

Mechanical Compliance of Suspension (Cms)

BL Product (BL)

Diaphragm Mass inc. Airload (Mms)

Equiv. Resistance of Mechanical

Suspension Loss (Rms)

Efficiency Bandwidth Product (EBP)

Voice Coil Overhang (Xmax)

Surface Area of Cone (Sd)

Impedance at Resonance (Zmax)

Maximum Mechanical Limit (Xmech)

X₁₀

15", 381mm

8 ohms

700Wrms

37Hz

28Hz - 1.4kHz

click here for

guide

109oz., 3.1 kg.

0.375", 9.5mm

4", 101.6mm

84 - 168 liters

3 - 6 cu. ft.

4.5 liters, 0.159 cu. ft.

15.21", 386.4mm

14.0", 355.5mm

fitted as standard

fitted as standard

0.275", 7mm

14.56", 369.9mm

6.42", 163mm

26lbs., 11.8kg.

37Hz

4.95 ohms

1.21mH

0.48

9.42

0.45

163 liters

5.76 cu. ft.

677cc

0.1579mm/N

16.88 T-M

119 grams

2.919N*sec/M

76.8

7.9mm

856cm²

122 ohms

30.94mm

11.3mm

[DrWho]

That's the one!

If you have WinISD you will notice that it is already in the list of

included drivers so you won't have to manually enter them yourself.

Here's a link to the PDF: http://www.partsexpress.com/pdf/290-580.pdf

[jwc]

If you are going to run the WinISD program, try out some of the Eminence Delta drivers. They will also work with the project you are seeking. The Delta drivers are not as high dollar as the magnums and have the same type curve as a K33 in a cornwall cabinet.

The Magnum is a much better driver than the K33 I would guess.

It depends on what your project is. If you have flexibility with cabinet volume and porting, I would move away from the whole "K33" concept. I used the K33's in my dual setup because I wanted it to have bass just like a Cornwall.

[Al Klappenberger]

Tom,

Here is a possibility. It's the woofer driver Dman has chosen for his Jubilee clone woofer horn. I have measured one that he sent me and found that it is actually 10.2 Ohms in sereis with 1.6 mHy at 600 Hz. If you put two in parallel it would represent 5.1 ohms in sereis with .8 mHy. That is close enough to 6 Ohms in sereis with 1.0 mHy to work ok with my ES600 extreme-slope network. I'll let the rest of the problems invoilved with developing a ported box for two of them up to you!

Al K.

[jwc]

Al,

You confused me there. I though optimal woofers for your ESN's needed a VC inductance around 1 mH and 6 ohms. Is this right? Of course I wondered how the K33 with an impedance of 3.39 ohms fit in there.

Maybe it isn't as important to stay exactly on spec. So what I hear you saying is that having two woofers in parallel resulting in 5.1 ohm is ok as well as an inductance of 0.8 with your ESNs?

Maybe I just restated what you just posted. Now that I look at it; hell it is the same. I guess I was wanting to know how far off spec is allowed for woofer substitutions with your designs.

Also, I always wondered what you do with the VC inductance value when you wire in parallel vs series. What is the Rule there. Looks like the rule is the same as what you do for impedance. 1/2 for parrallel and 2x for series.

jc

[DrWho]

Them's some nasty peaks and dips with that CB-15 in the 100-500Hz

region. Do you really think it would be a step up from the K-33? Maybe

perhaps a lateral movement to obtain an 8ohm driver (but that seems

kinds silly to me).

What's the incentive to finding a pair of 8 ohm drivers? Wouldn't it be cheaper/better to just rework the crossover?

[Al Klappenberger]

JC,

The K33 is NOT 3.3 Ohms. It's roughly 6 Ohms in sereis with 1 mHy inductace.

The "ES" networks will work well as long as the woofer driver is roughly equal to the K33. As a round guess, 5 to 7 Ohms in sereis with 0.5 to 1.5 mHy should be ok. I have tested them into quite a few complex loads andt is not a critical thing. The more you depart from the K33 the rougher the woofer filter passband gets. It just becomes a question of how rough you can accept.

Becides, Tom is considering two drivers connected in parallel. That cuts everything in half.

AL K.

[jwc]

Here are most of your Eminence options with 8 ohm drivers.

[jwc]

Here is the jbl 2226 (green) and the E. Magnum LF (red) and K33 (white)

[DrWho]

Dude, you gotta optimize the cabinets and tunings seperately for each

of those drivers. Doing that dip before a round peak and then dropping

off sounds horrible (poor transient response).

I haven't modelled the other drivers, but I know you can get far far

better slopes with the magnum (in fact, you can match the cornwall

identically with the smaller cabinet or you can go with a flat fast

transient response and go about 10Hz lower).

Btw, I actually own a JBL 2226 and wouldn't recommend it over the K-33.

It's low distortion and all, but lacks a certain oompf to the sound. I

would describe it as sounding like a PA speaker [] (I've heard it

used in a few configurations and I'm definetly not a fan for home use).

[jwc]

Dude, you gotta optimize the cabinets and tunings seperately for each of those drivers. Doing that dip before a round peak and then dropping off sounds horrible (poor transient response).

I haven't modelled the other drivers, but I know you can get far far better slopes with the magnum (in fact, you can match the cornwall identically with the smaller cabinet or you can go with a flat fast transient response and go about 10Hz lower).

Btw, I actually own a JBL 2226 and wouldn't recommend it over the K-33. It's low distortion and all, but lacks a certain oompf to the sound. I would describe it as sounding like a PA speaker [] (I've heard it used in a few configurations and I'm definetly not a fan for home use).

Doc. Settle down. I responded to his initial post which was for alternative drivers in a Cornwall type cabinet. Yes. they look like crap. Personally, I wouldn't go for any other driver in that cabinet but the K33.

If i were to invest in a different driver, I would use different cabinets and ports.

jc

[D-MAN]

I have arrived at that conclusion, too. The K33E is optimized for a horn driver, and is best in a very particular horn, and it has some drawbacks as a reflex driver because of it.

Remember that PWK used what he had on hand, and evidently got a kick out of getting the best sound quality he could out of relatively cheap components. That was business.

First, its cone is a little light for direct radiating use. It's magnet is also a little undersized. It works, but HEY, there are many other drivers that are specifically designed to perform in areas that the K33E is not.

I would take the very sage advice mentioned above, and go for the gusto, and select a design and a driver specifically matched for it.

DM

[Deang]

When you horn load a driver, its impedance goes up. In the case of the K-33 -- it almost doubles. At any rate, it's spec'd out as a 4 ohm driver, and should probably be treated as such in a straight up design.

[D-MAN]

2- 8's wired in parallel would be just fine, and you could probably use a Klipsch-style crossover like Al K. said above.

The Magnum LFA is a fine driver, but 4 of them will be SPENDY.

Scratch that - 4 of anything is spendy, come to think of it!

DM

[D-MAN]

Them's some nasty peaks and dips with that CB-15 in the 100-500Hz region. Do you really think it would be a step up from the K-33? Maybe perhaps a lateral movement to obtain an 8ohm driver (but that seems kinds silly to me).

What's the incentive to finding a pair of 8 ohm drivers? Wouldn't it be cheaper/better to just rework the crossover?

You should not believe what the manufacturer publishes (or at least stay skeptical)! Especially frequency response curves (or sensitivity ratings either). It also has nothing to do with it being tested in a horn.

Al K's hands-on testing of the driver in question had a different outcome.

DM

[DrWho]

eeek, I wasn't upset at all....sorry if I came off that way.

D-Man, I would be curious to find out what you specifically find

lacking in the K-33 for normal direct radiating duty. Michael Hurd and

I have spent many hours modelling all sorts of drivers to find

something that definetly exceeds the K-33 in performance for a normal

ported application and we are yet to find any distinct winners. At

least I don't think we're overlooking anything....

[D-MAN]

Bear in mind that I selected the driver for a horn driver application only.

I believe in selecting the right tool for the job.

I think that it is best as a purpose-built horn driver rather than forced to do double-duty as a direct/reflex driver. It has some attributes that are quite specific to the small-slot horn loading application it is best used for.

The cone is too light (good for horn driver, bad for direct radiator), its Vas is too large compared to most "modern" drivers where the reduction of Vas is one factor that has improved over the years, in keeping with the desire to reduce cabinet sizes. It also has a somewhat rapid upper freq. mass rolloff compared to other drivers, good for the Khorn which crosses over at 400Hz, but not so good for a direct radiating application.

A larger magnet and a higher wattage handling ability would also be nice, IMO. This would basically mean an 8 Ohm vc right of the bat.

When used outside of a horn, it's reduced efficiency could theoretically promote over-driving the unit's somewhat limiting (by todays standards)150w rating.

Alot of this is opinion, although some of this is sound thinking.

DM

[DrWho]

So translated you don't like the size of the cornwall cabinet and you

want to get louder than 120dB max (which of course will reduce power

compression) []