Tune

JBL K2 9800

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Posted (edited)

They don't really Lindsay. Positioning a loudspeaker should be about how the F3 interacts with room modes and placing the speaker where bass modes are at their most even. That position doesn't really change IME. :) Visually sure - but positioning? No.

fullsizeoutput_2b45.jpeg

Edited by Tune
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28 minutes ago, Tune said:

They don't really Lindsay. Positioning a loudspeaker should be about how the F3 interacts with room modes and placing the speaker where bass modes are at their most even. That position doesn't really change IME. :) Visually sure - but positioning? No. 

Different speakers will trigger different modes if placed in the same position and floor-bounce will most likely act differently too. Even a change in stand height will affect the response below 300Hz.

You can visualise these effect by playing with this simulator: https://www.hunecke.de/en/calculators/loudspeakers.html

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1 hour ago, lindsayt said:

It's a shame they don't work well in your room with their backs closer to the wall, so that you could say "They don't even take up more real world floor-space than a pair of tiny ported standmounts."

Someone said that about the Snells that I bought - I laugh about that now :nup: :D

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Posted (edited)
38 minutes ago, tuga said:

Different speakers will trigger different modes if placed in the same position and floor-bounce will most likely act differently too. Even a change in stand height will affect the response below 300Hz.

You can visualise these effect by playing with this simulator: https://www.hunecke.de/en/calculators/loudspeakers.html

Not really IME Tuga. I know the theory - I used to work with Peter Lyngdorf in the early days of TACT. In practice, again IME, it comes down to F3, position and of course design of box (ported or not). Again, just my own experience although I have entered that stage in life where I just listen for music and tone :) The vertical mode, in almost all situations, has been irrelevant to overall performance - again IME only.

Anyway, all I'm saying is that it doesn't worry me to the degree that it once did and I hear more music without worrying to that degree.

Edited by Tune
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So yesterday I demoed S9900 (K2) at the JBL dealer.  Very poor photo attached in a dark room.  You can see Revel Salons next to them which I didn't listen to, plus some other JBL monitors.

I really enjoyed the mids and highs of the K2s...good separation and realness, a big open sound.  But with a 15" driver the bass was poor for the price.  Definitely need to add a subwoofer to these speakers and that shouldn't be the case with 40 grand speakers.  Maybe their cabinet is just too shallow.  

This was highlighted when playing the same tracks on the monitor...3 grand.  Ok the vocals were by far inferior but still good compared to many speakers.  But the bass was really good...punchy, present and deep.  Better than the K2s.  Both speakers nowhere near the rear walls.

JBL K2.jpg

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Super Wammer
4 hours ago, Carlbkk1 said:

So yesterday I demoed S9900 (K2) at the JBL dealer.  Very poor photo attached in a dark room.  You can see Revel Salons next to them which I didn't listen to, plus some other JBL monitors.

I really enjoyed the mids and highs of the K2s...good separation and realness, a big open sound.  But with a 15" driver the bass was poor for the price.  Definitely need to add a subwoofer to these speakers and that shouldn't be the case with 40 grand speakers.  Maybe their cabinet is just too shallow.  

This was highlighted when playing the same tracks on the monitor...3 grand.  Ok the vocals were by far inferior but still good compared to many speakers.  But the bass was really good...punchy, present and deep.  Better than the K2s.  Both speakers nowhere near the rear walls.

JBL K2.jpg

When I heard the same speakers at the Bristol show earlier this year they were - to my surprise - close to the rear wall.  Perhaps they are intended to work better that way than well out into the room?

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Right, let's try to put this right.

Firstly about drivers. Carl refers to the 1500al as a "Bass Driver".

328827.image0.png.91345968a8ecf3c756b49c60629ea350.png

In all JBL horn loaded monitors the cone crosses over at 800hz using a second order crossover - so it's only 6db down at 1.6khz etc.

The so called "bass driver" is therefore responsible for the fundamentals of the "mids" such as the vocals Carl was enjoying are almost entirely reproduced by the "bass driver" as is the case for so much of what people refer to as a mid. An ATC SCM150asl crosses over to the midrange dome at 380hz, an octave lower. Look at the tiny differences though in driver usage.

It's also worth mentioning that I am probably the only guy you will meet who used the 1500al in subwoofers I built a pair maybe 17-18 years ago. They are considered to be one of the very best 15" drive units designed in the last 50 years.

KICX0692.thumb.JPG.50635c935845df949723d2a2e464447f.JPG

Secondly large JBL's like this are designed to work in real rooms are are primarily aimed at the Japanese market. They are designed to be used within a meter of the rear wall and can be used a lot closer.

Again as you look at the chart. At low frequencies, the room acts as a big box so you get a +12db per octave boost in output as the frequency drops. The JBL has an F3 point (-3db) at 45hz. It is 18db down at 20hz. With room gain that is 6db down or flat to 28hz.

Now look at the chart again and consider that if you do feel the need for a sub, you are probably listening to a system that artificially boosts bass response (usually around 40-80hz). Alternatively the vendor had no idea how to set up the loudspeaker. That would be a shame but remember that the "bass driver" is also producing an awful lot of what you liked.

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I have to admit I really like what a big JBL does. I heard the 4367 driven by a 400w/channel amp and although that power was not needed it just kept everything under control and had so much headroom that the sound was relaxed and very powerful. This is a real contrast to a lot of weak-kneed modern bright monitors that have no real power and drive. JBLs have a bit of a bad reputation due to their lifestyle products but their audiophile products are differently focused. And normally they are not that badly priced.

Horn-loaded speakers just have brilliant communication of music.

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10 hours ago, Tune said:

In all JBL horn loaded monitors the cone crosses over at 800hz using a second order crossover - so it's only 6db down at 1.6khz etc.

Being pedantic here, but if it's a second order acoustic crossover it will be 6db down at the crossover (800hz). And according to LspCAD it will be about 14db down at 1.6khz. But even so, that big driver is doing a lot of work in the high frequencies.

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16 hours ago, Carlbkk1 said:

So yesterday I demoed S9900 (K2) at the JBL dealer.  Very poor photo attached in a dark room.  You can see Revel Salons next to them which I didn't listen to, plus some other JBL monitors.

I really enjoyed the mids and highs of the K2s...good separation and realness, a big open sound.  But with a 15" driver the bass was poor for the price.  Definitely need to add a subwoofer to these speakers and that shouldn't be the case with 40 grand speakers.  Maybe their cabinet is just too shallow.  

This was highlighted when playing the same tracks on the monitor...3 grand.  Ok the vocals were by far inferior but still good compared to many speakers.  But the bass was really good...punchy, present and deep.  Better than the K2s.  Both speakers nowhere near the rear walls.

Less bass extension is a price you have to pay for high sensitivity.

But I think that, from your description, perhaps the monitors have exaggerated bass, something which you happen to enjoy/prefer, or they work better in free space.

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Here's a comprehensive test (in Italian) of the S9800s:

http://www.cieri.net/temp/JBL_K2-S9800_-_Test_di_Audio_Review_(05-2008).pdf

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Super Wammer

Here is a less comprehensive test... https://www.whathifi.com/jbl/k2-s9900/review

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Scratch - built a pair of 4430s earlier this year. I think there may be a thread in the diy section.

They IMHO considerably out perform stock, as the cabs are more rigid and very well braced, and the crossover uses much higher quality parts. Radian diaphragms in the HF too.

Had them at Kegworth, and will probably take them again next year.

Very revealing yet fun speakers. No sub needed - they go l-o-o-w. Great for dissecting music and production, and well recorded stuff just sounds addictive.

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