KLS3 and bass

[Brian]

Folks

People will know my "issue" with excess bass boom from my KLS3 MKII Gold speakers. Here is yet another episode in this continuing saga......

Over the last couple of years I've tried all kinds of things to sort out the bass boom from the KLS3, which spoils an otherwise fantastic sound. At one point I had given up on the MK II crossover and had settled on the MK I design, but I found overall this lacked power so I went back to the MK II crossover but added a 2R4 on the bass positive side to reduce the overall output. It's not too bad like this, however, I know it's a bodge and I just don't like the idea of a bodge.

Anyway, today I was able to put some test tones through the speakers and I found there to be a huge increase in volume between 60Hz - 69Hz...really massive imo. I don't like it and I'm wondering if this is the area that has been causing me such a headache for all these months, spoiling what is otherwise a sound that for me is almost where I want it to be. I'd be really interested in anyone else using the MK II crossover passing on the results of any similar tests they've managed to carry out. Stuffing the front ports made very, very little difference.

My plan for the weekend is to once again revert to the MK I crossover, I have upgraded components (Soniqs in the main) now since the last time I tried this so it may be better now. It's just very frustrating that I seem so close to the sound I want but am unable to make that final step.

Brian

[Richard]

Hi Brian, It may be worth putting your room dimensions into this calc and see if that f range crops up. If so, then the room may be the culprit; the speakers may be fairly flat response in free air but, having good bass output, may be exciting the room. I have a noticable thrum across my room at 32Hz, rattles the door, but I like it

[Brian]

Hi Richard

Thanks for the link.

Well the room isn't perfect at H22'8" x W11'8" x H7'8", but it's not enclosed. There is a fair sized opening along one side wall that leads off into the dining room, although very soon this opening will be closed off by adding double doors. I'm wondering now if putting doors on this opening might make matters even worse.

Brian

[Butterfly_pete]

Brian,

I had the same "over blown" bass problem on my KLS 3's with Mk2 crossovers.
So I borrowed my friends radio shack sound pressure level meter.
I also got a bass peak at 88 Hz. I also got a trough at 160 Hz.
The peak was about 10 dB.

I have only overcome the problem by putting in 2.2-Ohm resistors across the bass speakers.
Unfortunately these decrease the entire base and not only the peak.
The complete frequency response looks remarkably like the impedance curve for the original design.
In the Hi-Fi world supplement number 9.
The whole response approximates a 10-dB/octave increase in the high end.

My room is rather complex but approximates to 13.5 ft X 15.5 ft X 8.6 ft

Hope this helps.

Pete

[Brian]

Pete

Thanks for the info, it does help because it makes me believe that there is no fault in my speakers, that it's how they are. I'll revert to the MK I crossover tomorrow and see if the Soniqs caps I now have somehow give me a bit more power than the last time I tried this crossover design. It doesn't suffer from excess bass so that problem would be sorted.

If it doesn't work out I may finally give up on the KLS 3's. Despite how good they at everything else I'm not happy, so the "shopping around" will start up once again. I like the idea of 3-ways with a large bass driver, so I'd start with IPL S5TL's and perhaps the Wilmslow Forte. Perhaps I should even look for a new direction when considering speakers. I'll have to think about it and do some listening. It'll take time.

Speakers have always been the biggest problem to me, maybe it's because I've moved house so many times and each time the speakers haven't quite worked properly in the new room.

Thanks again for the post

Brian

[pre65]

Hi Brian-what is the rest of your system ?

I have a pair of KLS3,normal tweeter,and could never describe the bass as "overblown" !

Did i read somewhere that on the Mk1,the bass unit did not cover much range,handing over to the mid quite early ?



Philip

[Brian]

Originally Posted by pre65

Hi Brian-what is the rest of your system ?

I have a pair of KLS3,normal tweeter,and could never describe the bass as "overblown" !

Did i read somewhere that on the Mk1,the bass unit did not cover much range,handing over to the mid quite early ?



Philip

Philip

In MK I guise the bass-mid crosses at ~100Hz, in MK II it's at 400Hz.

The hump is at 60-69Hz according to the test disc I used. This tone is much, much louder compared to every other tone from 40Hz - 300Hz in 10Hz steps. I'm still only guessing that this is the cause of the bass boom, it may not be, but it will be interesting to revert to the MK I crossover and try the test CD again. I know that the KLS3 with the MK I crossover does not suffer bass boom, I used it like that for a couple of months at least.

The rest of the system is a Meridian 206B CDP and a Diy HIFI Supply Ella PP valve amp' in triode mode and with NFB disconnected.

Brian

[pre65]

Hi Brian-i'm not familiar with the power output of that amp but on mine they don't seem to "sing" unless they get at least 15W.

They were good with my Quad 11 (about 15W) but not so good with the 7W of a 300b SE.

That is why i went down the route with more efficient single drivers.

My amp range from 1.8W to 15W and the 206 Fostex in the VoFos handles them all with aplomb.

I would be loath to sell my KLS3 but to be honest they hardly get used these days.


Philip

[Greg.]

Hi Brian,

Just to bring your considerations back on track, remember we tried my KLS3's at your place with none of the problems you continue to have with your speakers. Knowing you've looked at everything and expecting chamber dimension and port tuning to be correct you will recall I remained at a loss for an explaination. Maybe going to MK 1 port tuning at the front would help?

I don't agree with Philip. My amp produces about 11W in Class A PP after I've dissipated and the speakers will sing well below this level.

Could it be a system mismatch? Remember, KLS3 were originally designed as a flagship speaker to work with flagship WAD 300B PP claiming 28W output. We know that's not true but I really wonder if your Ella is up to the mark. Having said that we are back at the point of my speakers working in your system so, regardless of the nightmare headache, I still think the emphasis should be on getting the speakers right. What about cutting your loses and simple replicating exactly what I have done simply because we know this works?

Best wishes,

Greg

[Ali Tait]

If you want to go down the DIY speaker route then perhaps you should consider an open baffle design.Very easy to build and many on here have done so. They can be very well done for not a lot of cash.I've heard several at our various get-togethers and they give a very open sound with very fast and accurate bass with no 'boom', so this type of speaker may well suit you down to the ground.Very efficient too so very few watts needed.Or try and demo a pair of WD's Aperiodics. Not heard a bad word said about them and many here use them too.
Regards,Ali