XLR to RCA to XLR

I now have Jensen transformers for the 107/2 and 102 KUBEs, plus a spare. I found that sound quality was better with XLR outputs from the transformers to the amps. Since my May '12 post, I've replaced the Proceed Amp 2 & 3 with Proceed HPA 2 & 3 (500 watts peer channel into 4 ohms).

Al,

The KUBE has a 2-prong AC plug.

I used a female XLR to male RCA adapter into the KUBE from the XLR line out of a Cary 11a and a male RCA to male XLR adapter to the line into a Proceed Amp 3.

Turns out I was using a KUBE designed for the KEF 102.2s I have in another system that has short lines between a Proceed PAV.PDSD and Amp 2, so unbalanced is no problem. But I'm negotiating the purchase of a pair of KEF 107.2s to replace the 104.2s, and a 107.2 KUBE is recommended by KEF.

Jedinite,

As I understand it, and my understanding may be incorrect, the use of a KUBE with the 104.2s is optional -- it only extends LF. In some applications, e.g. 107.2, the KUBE also tailors audio above the usual sub crossover. Thus, if you use a sub with your 104.2s, you may not need a KUBE.

The KEF museum is a treasure trove of information where you can download the installation instructions for the 104.2 as well as a nifty brochure that shows a cutaway of the speaker.

I have KEF 102s, 102.2s, 104.2s, and plan to buy 107.2s, so I've done lots of downloading and reading.

db

Mine was the winning bid on a Model 102 KUBE to use with vintage KEF 102 speakers I use for center channel. I've arranged with Tvad to try his Jenson ISOMAX transformers in the loop. I'll report back.

db

Tvad's ISOMAX transformers arrived today. I tried them using the KEF Model 200 KUBE that had previously caused the sizzle. The result was flawless: Silence at the speaker, and, even though designed for use with a different speaker, the KUBE provided substantial LF extension. I played the Ondine SACD of Saint Seans 3rd symphony. Pedal notes that were inaudible with the unaided 104.2s became audible.

Had I known the KUBE was so effective, I would have looked for one tailored for the 104.2s. Anyone have a lead on a KUBE for KEF 107.2s?

db

Sorry, Almarg, I don't, and I don't have a multimeter.

Tvad somewhat reluctantly sold his pair of ISOMAX transformers to me. Now I have to find a KUBE for the KEF 107.2s I'm buying.

db

Followup: I've installed a 107/2 KUBE using ISO MAX transformers. It provides LF extension to 20 Hz, although the 107/2s are not LF shy, and it seems to provide smoothing in the mid crossover regions. I changed the SACD output from the Oppo 95 to DSD rather than PCM, because the mains do not need to be supplemented by the subs.

Now I need to buy an ISO MAX for the 102 KUBE for the center channel.

db

Rdeckard wrote, "I only want the KUBE on the LF in a biamp'd config. I have read that even if you do not adjust the HF contour on the KUBE, it can still muddy up the wonderful midrange on these speakers just by being in the signal path, which is probably another debate altogether..."

According to the KEF museum, the KUBE is just an option for the 105/3, not integral to the design as it is for the 107/2. Why not just try it between the preamp and amp, and judge for yourself whether it muddies the midrange?

The 107/2 KUBE doesn't muddy the sound of my spectacular 107/2s that are bi-amped between the amps and the speakers.

db

Unlike the KUBEs that are integral to the design of the speaker, I think the only purpose of the 200 KUBE is bass boost. I had a 200 KUBE at one time and I don't recall if it had a button you can push to remove the boost circuit, but I suspect it may not. The 102 and 107/2 KUBEs I use both have such a button. I use those KUBEs without the added boost.

db