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Integrating a K-510(kpt-904HF) with a vintage Lscala bass bin


Jvitti1970

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40 minutes ago, moray james said:

K1000 is a horn with a 1KHz resonance, K700 is a horn with a resonance of 700Hz, K600 ha a resonance at 600Hz, K400 at 400 Hz and so on, so it seems safe to assume a K510 has a resonance of 510Hz. K700 typically used in the range of 750 Hz to 850Hz in Heresy and HIP and most all of you here know what that sounds like. You can play a horn down close to its resonance but it can no longer hold its polar control down there. The good rule of thumb is to cross a horn about an octave above its resonance and a standard minimum rule is no lower than 1/2 an octave above its resonance...............wavelength that is ..

 

Hey Moray, that is Cut-off frequency, the wavelength that is too long for the horn to load the driver, causing excessive excursion.   FYI, the cut-off for the K-400 is 278 hz, from memory, if it is mounted to a baffle. 

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Attached is a response curve run by one of our members on a La Scala bass horn.  It is quite usable to 1 kHz.   So, I would use a 700 to 800 Hz as a crossover to a K-510.  The thought of a 2" HF on a tractrix horn for my La Scalas is intriguing, but They are too pretty to cut up or place it on top. 

 

LaScalaBass response.JPG

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2 hours ago, JohnA said:

 

Hey Moray, that is Cut-off frequency, the wavelength that is too long for the horn to load the driver, causing excessive excursion.   FYI, the cut-off for the K-400 is 278 hz, from memory, if it is mounted to a baffle. 

yes of course that why you can play below that frequency thanks for the correction. I think I have seen a K700 being crossed as low as 600Hz but it is really not much of a plan. Thank you for the correction much appreciated.

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Regarding the crossover frequency....

 

The K510/69 (or it's now replacement) is the tweeter driver for several speakers.  It can be used for the entire top end on the Jubilee.

 

If memory serves me, Roy made the comment that since this driver is now being used in a residential situation, it can be crossed lower since it's not going to be approaching its full output.

 

 

 

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I think the question Joseph is really getting at is he has older LaScalas that he wants better sound from. Should he go with an active K510 or a crites rebuild of the drivers and crossovers in the LaScalas?

 

Personally I’d go with the K510s, I just think they are magical speakers. Some of that might be confirmation bias on my part, since I’ve been jonesing for them since first reading about them here some 15 years ago. But quite a lot of it is the secondary benefits of all active two way, which gets the most out of each driver. And objectively everyone that’s heard my new KLF-510 build loves the sound, so there’s that.

 

The other side of the coin is this is an expensive upgrade. You can get by with a miniDSP 2x4HD with a good attenuator on the HF channels for $250. Added to the 904-HF bundle that’s about $1500, assuming an extra amp lying around somewhere. I don’t know what a full crites LS rebuild runs maybe $750 tops?

 

So is an active 2 way 510 setup worth double the investment of rebuilding a LS? I vote yes.

 

 

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15 hours ago, JohnA said:

Hey Moray, that is Cut-off frequency, the wavelength that is too long for the horn to load the driver, causing excessive excursion.   FYI, the cut-off for the K-400 is 278 hz, from memory, if it is mounted to a baffle. 

 

I sure do miss Dennis and his 2x4.

 

With a low order filter, you ideally want to be a half octave or more above the Fc for the driver to load properly. The closer to the Fc you are, the steeper the slope needs to be.

 

From an old exchange between Gil and DJK:

 

"Well, I think Fc for the K-400 is around 271.2 Hz. That is based on the Lamed of 2.75 inches. Lamed is the distance in which the area doubles. But not to quibble."

 

"While this is true based on taper alone, PWK pointed out that when attached to a large flat surface (a Klipschorn) the added air mass lowered the cut-off to 240hz. This was his reasoning behind the truncated mouth areas on all the K400, 500, 600, and 700 series horns. This is also why the LB-76 had wings (and even the massive Altec VOTT A4 and A2)."

 

Dean

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5 hours ago, Coytee said:

Regarding the crossover frequency...

 

The K510/69 (or it's now replacement) is the tweeter driver for several speakers.  It can be used for the entire top end on the Jubilee.

 

If memory serves me, Roy made the comment that since this driver is now being used in a residential situation, it can be crossed lower since it's not going to be approaching its full output.

 

Right, but he's also employing steeper slopes. So, if the recommended crossover is 800 with 12dB/octave, you can slide it down to 500 and use 24dB/octave without having to worry about the diaphragm clacking.

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1 hour ago, Deang said:

 

Right, but he's also employing steeper slopes. So, if the recommended crossover is 800 with 12dB/octave, you can slide it down to 500 and use 24dB/octave without having to worry about the diaphragm clacking.

 

I'll experiment with 500hz on my 510s tonight.

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