Kef 104/2, to KUBE or not to KUBE?

canuckaudiog

On a quest for high fidelity
That is the question!

A few of you 104/2 owners out there are no doubt curious about what the KUBE can do for the 104/2. I happen to own one and I've been playing around with it today and thought I'd share my thoughts, now that I've completely restored the 104/2s. I did write up some thoughts on its addition when the 104/2s were unrestored with the original foam donuts caps and fluid and I remember that I felt it made a welcome addition then, but of course now they are back to factory spec and this can change things.

In short, I don't like it in circuit. I couldn't detect much additional bass, considering you're gaining only a little bit of LF extension (goes from about 50Hz flat to 35Hz flat), to me I could hardly tell much difference bass-wise between it on or off. I think you would have to listen to some tracks with deep bass to really benefit, but even then I couldn't tell a whole lot of difference. Maybe it's placement of my speakers, or maybe something isn't quite right with my KUBE, maybe it's the room. Although it works just fine. But seriously, I could not tell a whole lot of difference. With the Extension button engaged yes, I certainly could tell more of a difference.

What I really didn't like about the KUBE though is what it does to the midrange and treble. I found it added some grit to the sound and made it noisier. In other words, more distortion. I know the KUBE does attenuate the sound a bit here, but you could tell it was "dirtying" the sound. It made the midrange less enjoyable and less rich, making it overall tougher to listen to.

However, I have not given up on the KUBE for the 104/2. I still believe a large part of this has to do with the cheaper parts used. One of the folks who designed the KUBEs for Kef posts on another forum and mentioned they really only spent money on the 107 KUBE, which I guess makes sense, but it's unfortunate. My plan is to recap the 104/2 KUBE and replace the op-amps with OPA2604s just like I have done with my 107 KUBE. I have a feeling this will clean up a lot of the issues I'm experiencing.

Basically, I wanted to post this for you guys considering a 104/2 KUBE. My personal opinion is that unless you are willing to hotrod it a bit, stock it's not going to do any good for you. It certainly doesn't for me, and I think one of the sweetest parts about the 104/2 is its great midrange, so this is the last thing you want to detract from.

If you have a 104/2 KUBE and you're curious about doing what I am planning to do, it has 6 TLO72CP op-amps in it. I'm hoping that the OPA2604 will work in place, I can't find a single datasheet on the TLO72CP (lots on the TLO72) so if anyone knows anything I'd appreciate it.
 
...not to KUBE!

I agree that the KUBE adds colorations. I've had good success using the pre-amp section of an AV receiver with digital room correction which will also add the low end extension as well as address other room issues. However, the 104/2 need far more amplifier drive than a typical receiver can muster.
 
Hi Canuck, which KUBE model is the actual one designed for our 104/2?
It's a ways off till I might need one here lol but I think I would like to have one for my 104/2's
 
Has your KUBE ever been restored? I just built a Bose 901 equalizer from scratch, it was just a bare circuit board when I got it, so I didn't have a chance to hear how the original sounded. I used 1% metal film resistors everywhere, and replaced a few electrolytics in the signal path with films. The speakers/EQ combo sounded really great, much better than I remember the series 4 901s sounding, these were series 1. Only the chance to swap them for some interesting Dynacos persuaded me to part with them. Now the new owner wants me to restore another 901 equalizer he has.

Perhaps your KUBE needs a similar treatment?

Lee.
 
Has your KUBE ever been restored? I just built a Bose 901 equalizer from scratch, it was just a bare circuit board when I got it, so I didn't have a chance to hear how the original sounded. I used 1% metal film resistors everywhere, and replaced a few electrolytics in the signal path with films. The speakers/EQ combo sounded really great, much better than I remember the series 4 901s sounding, these were series 1. Only the chance to swap them for some interesting Dynacos persuaded me to part with them. Now the new owner wants me to restore another 901 equalizer he has.

Perhaps your KUBE needs a similar treatment?

Lee.

It's possible that may have solved the coloration problem. It's not a high end made EQ, that's for sure, but it does its job.

As for the model, I am looking at the box for it as I type this and it says:

"KEF REFERENCE SERIES KUBE 104/2
KUBE TYPE: SP 2089
AC ADAPTER TYPE: SP2104"

I hope that helps :)
 
Ah Thanks ^^
Hmm puzzling though Seems theres some specific kefcubes, kef-kube 104/2, I've seen a kef-kube 102, and then the kefkube 100 and 200 model which is more generic to the respective model line up?
 
Ah Thanks ^^
Hmm puzzling though Seems theres some specific kefcubes, kef-kube 104/2, I've seen a kef-kube 102, and then the kefkube 100 and 200 model which is more generic to the respective model line up?

The Kef models 104/2, 102, 103/3 and 107 all had their own, specific Kubes made for only that model. Whereas later Kef speakers like the 103/4 and 105/3 had a Kube that was optional (I believe the 100 and 200 models). They could be used interchangeably I think - but, for the 104/2, you absolutely want the one made for that model as it is specifically made for it and no others are.
 
I have yet to hook up my 104/2s to any solid state amp or receiver...I do not have a cube. From my experience with my Jolida and Maggie 175 is that the mid-range is what these speakers are all about anyway. Maybe I should hook them up to my NAD or Adcom and see how they sound. I tend to ignore mine because I have Snell Type III/Series Es, Yamaha NS-10ts, Mirage FRX7s and JBL 4406s in the same room lol.
 
Well for me it's all future music still, until I have the 104/2's fixed up. Going to sell my b&w matrix 3's which have been with us for oh heck 20 years. the 104/2's natural sound is a memory in my head 20+ years old,but going on comparative opinions of the two, bass wise most favour the matrix 3's. My wife would miss the bass lol so yeah I think I will keep my eyes open for a Kube 104/2
 
when in doubt, KUBE.

I did not notice any midrange coloration upon engaging elKubo.
 
I didn't care for the bass/midbass on my 104/2s and I was not using the Kube.
I always thought it sounded a tad muddy.
 
I don't have KEF that have optional Kube, or came with a Kube.
I always thought the Kube was there for the mid-bass/mid-range.

It will be nice to know what you think after you recap the 104/2 KUBE and replace the op-amps with OPA2604.
 
The main job of the Kube was to give a more extended bass response. There were other corrections higher up on some but they were smaller. Kef also took advantage to add some adjustments to make integrating the bass with the room easier, the original series of 107 Kube having the most in the way of adjustments.

It is normal that Canuckaudiodog only noticed a significant difference with Extend engaged. That is the position that gives the low frequency response the designers were aiming for with the speaker/Kube system. The idea was to disengage extend in order to limit bass response if it was causing problems with LP playback or room interactions.
 
As I've read, the KUBE was an "afterthought" with the 104/2. The 107 was designed from the ground up to use active equalization (the KUBE) and the KUBE "solution" presented itself to improve the 104/2.

So, I would guess, the 104/2 sounds good enough to be called "Reference" without the KUBE but should give an even better lower frequency octave with it.
 
Pretty much. After they had designed the 102, 103.3 and 107 they applied Kube technology to the existing 104.2 making it the only one of the group where the Kube was optional. It also gave them a nice potential add on sale to all of the people who had bought the 104.2 over the years.

Kubes remained optional on all later designs as it was costing them a lot of sales. Not everyone liked the idea or could make a Kube work with their set up, particularly in the exploding multi room market of the day.
 
The primary purpose of the Kube is to extend bass response from 40 to 20 Hz on the 104/2' specifically without coloring anything above 40Hz. YMMV, but mine sound best with the KUBE on "Extend+1".
 
i just picked up a a pair of 104/2 yesterday.
well maybe picked up is the wrong term... these are heavy speakers!

i have dittons and missions and small kef.
was using paradigm 9se for 2 chan[too much low end\low mid]. the kef blow them away. but i find them lacking in bass.

i am using a nad 2200 to drive them. has anyone tried just a regular eq?
i have a collection of them best being a soundcraftsmen pro .
 
I know this is an old thread, but wanted to add my 2 cents.

I picked up a proper KUBE for my 104/2. Had a fellow AK'er re-cap it and check it out.

In short, I do not like it and it's not in the system. I'm older, but still have good hearing. I can definitely hear upper-mid and high frequency roll-off when using the KUBE. It's not worth it to me for any bottom-end extension it provides.

It's nice to have the KUBE to go with the speakers, but don't think you're missing something without it. I like the speakers as they are.
 
I've the gamut on this era kef reference speakers and agree that there is noticeable hf and mf rolloff. If you are using the later kube optional models and are running a single amp your going to hear it's deficiencies.

With that being said the kube also brings the low end to life on these speakers. Run them in a horizontal biamp configuration with the kube on the lf circuit only and you'll really hear your speakers sing. Have run this configuration primarily with an integrated + power amp for the lf and I cannot see myself moving away any time soon. Some component matching comes in to play here but it's totally worth the effort.
 
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