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Multi-Way Conventional loudspeakers with crossovers

KEF LS50
KEF LS50
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Old 10th April 2013, 11:18 PM   #91
Face is offline Face  United States
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The 8" unit has a break up that's a little more work to deal with. Plus, it's a little more efficient and has a little more extension. In a 3 way, I would go with a 5.25" unit.
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Old 12th April 2013, 03:53 PM   #92
Pallas is offline Pallas  Pakistan
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Originally Posted by The Rug Doctor View Post
My question Is this - which driver'should i experiment with?? I have been looking at the Q100 and the Q300 drivers, one is a 5.25 and the other a 6.5 cone.
Having compared the Q100 and Q300 back-to-back, the Q100 drive unit is clearly superior, IMO. The Q300 struck me as sounding more like a typical "high end" speaker in the midrange, whereas the Q100 sounded more like music and less like the can it came in.

When I looked them up after the fact, I realized why: same tweeter size, same published crossover point, but the Q300 has a bigger midrange. So the Q300 does the "midrange mushroom cloud" thing that one hears in standard 7" midwoofer/flush tweeter "high end" speakers to some degree, because the woofer unavoidably narrows in coverage before the tweeter can come in, whereas the Q100 has better-controlled midrange off-axis response. The geometry of the LS50's driver is substantially similar, and the driver sets the overall directivity. So while I've not seen good polar measurements of the Q100 here's Stereophile's horizontal off-axis curve for the LS50:

Click the image to open in full size.

(The lower-diffraction cabinet will make the LS50 smoother than the Q100. The other differences in drive unit and crossover may make the LS50 superior in other ways, but don't have as much an effect on the midband directivity.)

You see a little hole developing far off axis in the midwoofer-tweeter transition, but smooth performance closer in. Holes in the off-axis response have been shown to be relatively benign. Peaks (as one typically sees at the bottom of the tweeter's range in a so-called "high end" speaker, resulting in what I call a "midrange mushroom cloud")

So I suspect that the differences I observed between Q100 and Q300 go back to the drive units themselves, rather than to implementation.

The 8" Uni-Q in the Q900 is a different animal, with a much larger tweeter and lower crossover.
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Old 12th April 2013, 08:06 PM   #93
The Rug Doctor is offline The Rug Doctor  United Kingdom
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Thankyou Pallas, I appreciate your post a lot. So do you know the best xo point and slopes for the two drivers? (100 & 300)?? I have managed to borrow a set of Q300 to have a play with but am going to run them active..

Also, this peak you mention of the 300 driver, the swelling midrange, I'll hopefully be able to eq that out as I use Rane 30 band EQs together with an upgraded Rane active XO, what do you think?

I have REW and an audiocontrol rta to play with..
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Old 13th April 2013, 07:19 PM   #94
Pallas is offline Pallas  Pakistan
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Originally Posted by The Rug Doctor View Post
Thankyou Pallas, I appreciate your post a lot. So do you know the best xo point and slopes for the two drivers? (100 & 300)?? I have managed to borrow a set of Q300 to have a play with but am going to run them active..

Also, this peak you mention of the 300 driver, the swelling midrange, I'll hopefully be able to eq that out as I use Rane 30 band EQs together with an upgraded Rane active XO, what do you think?

I have REW and an audiocontrol rta to play with..
I wouldn't be so sanguine about the ability to EQ out the midrange mushroom cloud. It's not just an on-axis peak, but a basic difference in the amount of energy thrown out by the different drivers as one moves off-axis, because they have different radiation patterns. The only way to solve the midrange mushroom cloud issue is to cross the tweeter low enough that it matches the midrange's pattern in the crossover region. That requires taking polar measurements of each device.

But I suspect that the tweeter just won't go low enough to do it, because KEF's crossover uses the tweeter's rolloff as an element. (The Q100 has a very, very low parts-count crossover, just IIRC a single inductor on the midwoofer, and a cap + resistor on the tweeter. It's not perfect, but it's darned good.) I don't know what kind of crossover the Q300 has, because I've never owned one and never opened one up.

Still, you could probably get a very good result in your room with the Q300 driver by using your tools and perhaps some sidewall damping in the room. You'd have a higher likelihood of success if you ditch the RTA for a higher-resolution computer measurement system, such as FuzzMeasure (Mac) or Omnimic (Not-a-Mac).
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Old 17th December 2013, 05:42 PM   #95
etalon90 is offline etalon90  Canada
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I have the Kef LS50 and I was a bit dissapointed at first
boomy and a bit of reverberate in midrange.

I opened them up and replaced the filling from pieces of foam to roxul safe n sound fiberglass.


MUCH, MUCH BETTER.
Bass is more realistic and extend a bit more (subjective)
Bass port have about 8db less midrange radiation vs original foam at 1K (ok, only measured with my RS splmeter)
Pink noise sound a bit more neutral.
HF seem unchanged.

I wand to remove crossover and inspect caps.
they are wrapped in a kind of wax and one can't tell type or brand...

I'm waiting for silverplated solid wire to upgrade internal wiring before opening again.

Picture to follow.
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Old 19th December 2013, 07:34 PM   #96
rpnfan is offline rpnfan  Germany
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Originally Posted by etalon90 View Post
I have the Kef LS50 and I was a bit dissapointed at first
boomy and a bit of reverberate in midrange.

I opened them up and replaced the filling from pieces of foam to roxul safe n sound fiberglass.


MUCH, MUCH BETTER.
You might be interested in this Pimp (text in german, but the measurements and the like should be interesting):

http://www.hifi-forum.de/index.php?a...ack=&sort=&z=1

http://www.hifi-forum.de/index.php?a...ack=&sort=&z=2

Here are measurements of the stock LS:

http://www.hifi-forum.de/index.php?a...0&thread=32137
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Old 21st August 2017, 04:48 PM   #97
rhing is offline rhing  United States
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Interesting thread here that has been dormant for a few years. I recently purchased a pair of these speakers from a local dealer, Halsten Entertainment, in Minnesota, and I have been listening to them in my townhome apartment living room area. My apartment has an open floor plan with the living room, dining room, kitchen and staircase combined into approximately 720 square feet (66.9 m^2).

I recently moved from a large house in another part of the US, so I reluctantly put my Klipsch Forte II floorstanding speakers in long term storage. My amplifiers are as follows:
  • gmarsh Wiener 2 TPA3118 PBTL dual mono Class D amplifier with Altec Peerless 15335A input transformers to feed unbalanced inputs into the amplifier's differential inputs. This amplifier is powered with an upgraded Astron RS-12A regulated linear DC power supply. Approx. 12 watts/channel
  • Dynakit Stereo 35 6BQ5/EL84 P-P tube amplifier recapped and modified with Dave Gillespie's Enhanced Fixed Bias (EFB) circuit. Approx. 17 watts/channel
  • McIntosh MC240 6L6GC P-P tube amplifier recapped with the bias supply and power supply upgraded with fast, soft recovery diodes. Approx. 40 watts/channel

My amplification also includes an Audio Research PH5 JFET/tube phono stage and Audio Research LS7 tube line stage, which provides 13dB gain unbalanced.

In moving to a smaller space, I needed smaller speakers, so I researched efficient monitors like the Reference 3A MM de Capo's and Omega Speakers Compact Hemp's thinking that I would need at least 90db+ sensitivity to work with my modest power amplifiers. I even considered putting my amplifiers aside in favor of powered studio monitors like the Dynaudio BM5A MkII monitors. I never considered the KEF LS50 speakers, because when I heard them at an audio show in California a few years ago, I was not impressed at all. They had a harsh, glaring upper midrange and no low frequency response at all.

Well fast-forward to last month while I was on vacation in Boston, I stopped in Audio Lab in Cambridge, Massachusetts and listened to a pair of LS50 speakers driven by a Cambridge Audio SS integrated amp. I was drawn into the sound much like Joe Roberts described in earlier posts in this thread. This was not the same speaker I heard at the audio show years before.

When I returned to Minnesota, I went to Halsten Entertainment to audition the LS50 speakers again. This time, the speakers were powered with a more powerful and more expensive Rotel SS integrated amplifier. Again, the speakers were very engaging, coherent and rich with tone. The large soundstage defies the size of these speakers. Well I decided then to purchase a pair at a good price offered by Eric at Halsten's.

I am very impressed that my Class D and Dynakit Stereo 35 amps can drive these speakers to very loud levels in my open apartment space. I am able to get strong room reinforcement for plentiful low frequency response where I do not need a subwoofer for thorough musical enjoyment. I like to use large scale orchestral music for listening tests, and these speakers do not disappoint at all. In fact, I can't go past 10 to 11 o'clock on the volume control without disturbing my neighbors.

I love the ability to really hear the mix that the recording engineers achieved with each piece Inlisten to. I can see why some professional sound engineers have even used these as studio monitors, they provide such a clear presentation in many respects. Poorly recorded and mastered music will not sound great with these speakers. The same can be said about sub-par quality upstream equipment paired with these speakers. I liken the sound quality to the highly acclaimed Tetra speakers in terms of their dynamic response, imaging and soundstage, and tonal accuracy.

I have yet to try my MC240 tube amp with these speakers, but I suspect I will be very pleased when I do. As others have stated elsewhere, these speakers do require some time to really break in, but once they do, they produce a "big" sound that belies their compact dimensions.

KEF's engineers have done an outstanding work developing such a well integrated speaker system. I don't think I would ever be tempted to open these speakers up and make any modifications. I am not sure one could take any Uni-Q driver and develop a satisfying system without all the sophisticated tools and experience that KEF employed to create their flagship speakers including the LS50. These are different from the often-referenced LS3/5a monitors, but similar in that they are game changers.
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Last edited by rhing; 21st August 2017 at 04:56 PM.
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Old 17th January 2018, 11:17 AM   #98
simon dart is offline simon dart  United Kingdom
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Just to share my LS50 tweeks. This speaker is outstandingly engineered in my opinion but inevitably built down to a price. I wanted to get the best possible performance out of mine without going crazy so...

The binding posts are fairly nasty, Mundorf TPCU670 drop straight in. I replaced all the crimp connections with soldered joints and used HDPE insulated solid core wire for the internal wiring.

The caps are good quality so they've stayed, and similar DCR inductors (didn't want to mess up the bass alignment)would be a marginal improvement for lots of money spent I felt. So I just replaced the sand cast resistors with Mills.

I Dynamatted the front baffle and cabinet sides but left the foam scheme in place. I may revist that in the future, but right now it's not a priority because I'm too busy enjoying my music....

Bass is much tidier and more tuneful, the noise floor has dropped a notch or too and the HF has now lost it's last trace of glare. I think it's insane how much these can give for the money in a small to medium size room. I've now lost all interest in DIY speakers
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Old 17th January 2018, 11:54 PM   #99
Davey is offline Davey  United States
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Just to share my LS50 tweeks. This speaker is outstandingly engineered in my opinion but inevitably built down to a price. I wanted to get the best possible performance out of mine without going crazy so...
"Built down to a price?"

No, I don't think so. The LS50 is a speaker that's not competitively priced....considering the resources KEF has.
Check out the Q100 for a speaker that qualifies for your comment.

Dave.
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Old 18th January 2018, 04:54 AM   #100
GringoAudio is offline GringoAudio  Canada
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I have heard the LS50 in two locations of the fairly mid-market Visions chain in Canada. They were completely underwhelming both times. If these are good speakers Visions doesn't have the equipment to drive them nor the sound rooms that flatter them. I would never buy them based on what I heard. Flat dull and sounded like a tin can.
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