Crossover Frequency of the K2 s9500

[Niklas Nord]

Hello

I have been thinking of using an active digital crossover for my K2 s9500. The freq is now at 650hz, that is what the manual is saying.

Is this not very low? I wounder what would happen if i would higher this.

I thing i have great opportunities to test this with an digital crossover, test some ranges...

The drivers in the K2 is the 1400nd and the 475nd horn.. driver..

[Earl K]

Hi Niklas

Is this not very low?

No that's not low at all for the size of that H9500 horn.


I wounder what would happen if i would higher this.

If you start raising the crossover frequency, the midband coupling you are now getting from those 14" woofers, will disappear in the range above say 600 hz. Depending on the education level of your ears - you may or may not "sense" when starts to happen. The loss of this coupling will reduce the "focus" from this area that is quite akin to a point source sound when a compression driver is physically set into the middle of this zone ( MTM ).

regards <. Earl K :)

[Niklas Nord]

Okey, I know al of that you said. Offcourse it´s like that.

BUT, I would like to know, how mouch can this driver take?
Now i feed it with 300 watts.

What happens when i stress it, play to loud?

I will be very interesting to use active crossover with this
loudspeaker..

And maybe a digital ampfilter to minimise the noise..

[dennis j leisz]

Niklas, Is there some design goal your after which the engineering talent at JBL was unable to with the K2? There are many companies with large research and development budgets who can afford to put enormous amounts of talent and equipment into interesting programs such as the K2. I am curious for your analysis of the weeknes of this product and what your upgrades will do to improve its characteristics. I'm also interested in the types of frequency measurement instruments you have in your lab to analyze the effects of your modifications. This past summer I modified a pair of L112s' with new crossovers and L100 century gold woofers. The crossover design was based on the original JBL circuit but with new high end inductors and capacitors. Newer copper wire as well. I also ommited the pots. We fine tuned the final product with Cleo software. This product is a big help for speaker design hobbyists. I found out years ago that ONE small change can have a major effect elsewhere.I am always interested in new ideas which we can use to add more to our hobby and passion. Giskard said it best; Try it to see if it sounds better. Regards Dennis a.k.a Audioden

[JonFairhurst]

Niklas,

The 4430 studio monitor (2235H woofer with the big-butt horn) uses a 1kHz crossover. The justification is that the 15" woofer has 100 degree dispersion up to that point. Above 1k, the horn takes over with 100 degree dispersion up to the 16 kHz roll-off.

To me the K2 9800 fixes some of the 4430 problems. First, the drivers use the latest technology for some small, overall improvements. Second, a UHF driver is added to extend the upper range. Third, the woofer crossover is lowered to reduce distortion in the lower mids (600-1k Hz).

By raising the crossover you will extend the dispersion in the 600-1k range - both vertically and horizontally. You will also increase distortion in this range as a 15" cone is a big surface to move at 1kHz. It's not perfectly stiff and will have some unwanted modes as the frequency goes up.

So, overall I'd recommend staying with the original setting, though if you bi-amp and the crossover is variable, you can try various settings until you find one that you like.

Regarding digital amps, you might try one for the HFs, since the noise that we typically hear from amps is HF noise. Also the cool thing about digital amps is their instant slew rate, which is perfect for HFs. If the LF amp is making audible noise, you can add a LPF between amp and speaker, say, at 1kHz. The LPF will cut the noise, but won't affect the crossover region. A behemouth solid state amp is probably still the best for LFs.

[JonFairhurst]

Sorry Niklas. You wrote s9500, and I read s9800. My mistake. Then again, it was a free upgrade :-)

[4313B]

"I found out years ago that ONE small change can have a major effect elsewhere."

Yeah, it's goofy isn't it? :p

[TimG]

If you are convinced that you need to alter your crossover frequency I would highly recommend getting yourself a measurement system and a crossover CAD system. It will be a tiny monetary investement compared to the cost of your speakers and will you save you a lot of time and money versus trying to buy parts and tune by ear or use cookbook crossover formulas.
For $129US you can get LspCAD, which includes an MLS measurement system and crossover and box modelling. For $225US you can buy SoundEasy 8.0, which includes a measurement system, crossover design, and the ability to model and listen to crossovers through your computer before actually building them.
Both of these programs will allow you to model passive and active crossovers. You will need to purchase a microphone and possibly a preamp to use with these systems, but a Panasonic capsule microphone is very inexpensive. Inexpensive designs for using these mic capsules can be found here http://www.linkwitzlab.com/sys_test.htm#Mic
These systems will work with a sound card like the Creative SoundBlaster series or you could go with something fancier like the M-Audio Delta 410 for around $120US. Both of these software systems have user support groups on Yahoo to help you get started and answer questions.
If you want to get really fancy you can buy a dedicated measurement system like Clio, but that involves a much bigger monetary investment.

[JonFairhurst]

Behringer has a reference mic that's only about $30. Keep in mind that it has a balanced XLR output, and needs phantom power, so you need some sort of a mic preamp.

A lot of computer music people go for the M-Audio Audiophile 2496 at the low-end of the price range. I prefer (and own) the EchoAudio MIA, which is only a touch more expensive, but has balanced TRS I/O and supports four stereo "virtual" outputs (i.e. it has one stereo out, but four stereo output buffers and an on-board 4x1 mixer).

Measuring is important, but I have to admit that I've been tuning my bi-amped system to taste lately. It's a whole lot quicker, and if it sounds good to me...

[TimG]

I forgot about the Behringer microphone, that is a good deal. The reason that I mentioned the Delta 410 is that is allows you to listen to 4 way stereo speaker crossovers using SoundEasy because it has 8 output channels. However, it is not the only soundcard that is capable of doing this. If you just want to experiment with 2-way crossover frequencies you could buy something like a Rane AC22 and add a capacitor to correct for high frequency rolloff. The used Rane models seem to hold their ebay value fairly well so you could resell it if you decide to build a dedicated crossover.

[Niklas Nord]

The first thing is to try Active crossover, THEN
i may try to alter some crossovers...

NOT a complete makeover..