What taps setting for Kef LS50?

[mcanaday]

Hello, all.

I'm very close to pulling the trigger on the new Rogue Cronus Magnum II to pair with my Kef LS50s. I have my Kefs now with Rogue Sphinx--which I have enjoyed--but I'll be moving that along to my desktop system.

I have never had tubes and have two questions: The first is whether I want the taps on the amplifier set at 4 or 8 ohms?

Here is what John Atkinson says about the LS50s in Stereophile:

"Somewhat optimistically specified at 8 ohms, the LS50's impedance (fig.1, solid trace) drops to 4 ohms at 200Hz and to 5.4 ohms at the top of the audioband. The electrical phase angle is generally mild, but the combination of 5.3 ohms and –41° at 135Hz, a frequency where music often has high energy, will make the speaker work at its best with a good, 4 ohm–rated amplifier."

So I am thinking that probably means I want the taps setting to be 4 ohms? But are there other considerations, or does it just come down to personal preference?

My second question has to do with the CD Player. I have a Rega Apollo R now (no problems to report) but am also thinking of sending that to work and investing in a Line Magnetic 515 cd player to run with the Cronus Magnum and the Kefs. My question is if anyone has any experience matching LM players with Rogue gear. Will things will get too "tubey" this way? And apologies if this is a dumb question--other than those 2 tubes in the line stage of the Sphinx I have mostly stayed on the solid state side of the line, so this is really a new venture.

Thanks, as always, for your thoughts!

Margot

 

[RGA]

No - you can run an all tube system - indeed, that is my preference and Line Magnetic's 515 is a fine match for Rogue. My Line Magnetic dealer here in Hong Kong sells Rogue Audio and melody - the ONLY CD player they use is the 515 and it's about as good as CD players get for the money. Which doesn't mean it's perfect - it leans to the sweet side of the spectrum but as weaknesses go I would take that over the opposite which is what many players exhibit.

As for the LS-50 I would use the 4 ohm taps. The speaker dips to 3.2 ohms at various frequencies and using the 4 ohm taps makes it less demanding for the amplifier.

I was actually about to sell the KEFs but had a last minute change of heart and will now use them in a second system for home theater.

Now I have to find a SS home theater capable amp - jeez - I'm giving myself a nightmare task now. Good and home theater is like oil and water - we shall see.

 

[RGA]

Good HT is not like water and oil. The trick is to have all timbre matched speakers and make sure your subs are turned down. Too many people don't tune their systems well enough.

I had home theater in the mid 1990s and always meant to get back to it. I live in Hong Kong so space is fairly tight. I am not nearly as picky on home theater so I am somewhat contemplating using my E's as front and my AX Twos as dual center channels that I can place on either side of the TV on a concrete slab. The KEFs will serve as rears (Uggh I know). My alternate plan was to buy a complete M&K system but that will cost more and subs will take up more space. The AN E can already head down to 20hz territory.

I'm thinking OPPO 105 for the blu ray and preamp processor into something like the Parasound 5 channel amp - though there is a pretty cool 5 channel tube power amp from Meixing for under $2000 which looks like oodles of fun albeit at 65kg (143lbs)

 

[Art K.]

I really like my HT and we did it on the cheap. Wharfedale Diamond 10.1's front and rear and the matching center channel with a Hsu Research STF2 sub. Marantz 5000 series AVR and an Oppo BDP103. Inexpensive (like $60) series Wireworld HDMI cables and Belden speaker cable all around. We have a 55 inch Panny plasma and are quite satisfied with the setup.:thmbsp:

 

[mcanaday]

Thanks, RGA and all. I had ruled out an LM amp for my Kef ls50s (to be honest, I cannot remember why!) but it looks like you have them set up together. As you also know Rogue, do you think one makes more sense than another for the Kefs? And if LM would be superior to Rogue,which LM should I look at?
With thanks and good luck with the HT! Margot

 

[RGA]

Rogue tends to have more power and may be more suitable for the LS-50 - further Rogue has more US dealers and more support should something go wrong. It depends on how big the room is - The Kefs will be fine with the 211IA and it's got a little more warmth and sounds a little more traditional valve like than many. And I would say this is somewhat the point of a going to a tube amp. Rogue Audio is also American made etc and may fetch more on the second hand market should you decide to sell it. It may also have more connection options.

 

[mcanaday]

Thanks, RGA. This is very helpful. I see the LM 501a does have 100 wpc and has a smaller build (which is appealing to me.). It is quite a bit more money. And there aren't a lot of reviews of the 501a and Rogue is such a known commodity to me and many seem to pair it with the LS50s. But your comment about the point of going to tubes is to have it sound like tubes is a good one to ponder. Hmmm. I do see there is a Line Magnetic dealer in my area who carries Kef too so maybe I will slow down and go take a listen. I would love to do this right and just be done.... Thanks!

 

[mcanaday]

ps I suppose another thing to factor in is that with the Line Magnetic. I would need to get an external phono stage for my Rega TT, whereas with the Cronus Magnum there is a decent one built in. Hmmm...

 

[mcanaday]

RGA, my apologies. I just now realized you are a reviewer for Dagogo and read your (very nice) reviews of the 219 Ia and the Kef LS50s, both of which were helpful. Although I realize the 219 Ia is a different amp than the 501 1a, I am encouraged that you like them together. Do you think it's safe to assume that the LM 501 1a would have a similar sonic signature/synergy with the KEFS or is that impossible to say because the amps are pretty different types? And is your statement in my post that the Rogue may be more "suitable" to the KEFS just about wpc, or do you think it applies when the Rogue is stacked up against the 100 wpc LM 501 1A as well? So far the only information I have been able to gather has been from Line Magnetic dealers (they have been very helpful), so it would be great to have an outside opinion from someone who knows the KEFs as well as you do. And anyone else who wants to chime in! with many thanks!

 

[OnTheEllipse]

Good,luck on your search. I'll be following with interest. Just to add to the data pool: I was running the LS50's with a Brio-R and then switched to a Yamaha A-S2000. The difference was greater than I expected. The much more powerful Yamaha has so much more authority...it really woke the LS50's up, especially I'm the bass. Because of that experience, I'd be inclined to lean towards more power than less, given the option. Looking forward to where you end up. I plan on picking up the LM DAC to round out my setup

 

[RGA]

The dealer in Hong Kong likes Rogue Audio better than Line Magnetic and in a recent shootout the Rogue Audio preamp beat a double the price Line Magnetic - so don't discount Rogue Audio. I just have not heard KEF with Rogue so I can't comment on what that will be like.

The thing is not to base opinions by brand but by specific items. For instance I am known to be an Audio Note fanboy but in truth there are a lot of products I don't particularly like or think are good value. For instance I chose my OTO over the more expensive ($3,000 list more expensive) SORO and I would take the OTO and my LM 219IA over the SORO or the Meishu which goes for $22,000. I like the Jinro better but at $26,300 that's not really doable and even then for that money it isn't quite perfect and for that money it should be. Hated the Shindo MonBrisson - but the Shindo Petrus is a world class Preamp. Like the Vosne Romanee as well - not their power amps.

I like the 219IA versus numerous other tube integrated amps and there is currently a nice write up on audioasylum's amp forum about from an ex reviewer. http://www.audioasylum.com/forums/amp/messages/20/203836.html

There are typically hit and miss products in every company for me and this is ESPECIALLY true of tube amp manufacturers. SS makers typically use the same general design and as you go up the line they provide beefier transformers but they generally sound very similar. Indeed, Bryston used to say their amps sound exactly the same and the only difference was power output.

With tube amps it's totally different - they make products that are inherently different from one another. Line Magnetic makes push pull amps, SET amps, amps that follow classic Western Electric designs, all kinds of different speakers.

I have liked Rogue separates but not so much their integrated amps - I like Line Magnetic's integrated but not so much the preamp (although they make several completely different preamps and it's possible I would utterly love one of the others.

The KEF is somewhat problematic and it falls into a problem zone for me which I mentioned in my review. I prefer ti with a SET amp but it's fair that other point out that it needs a lot of power. The 219IA has plenty of reserves and big power supplies to handle the impedance but it's still not a tube friendly loudspeaker. The problem is that it's kind of designed IMO for people who intend to run 100 watt SS amplifiers. Unfortunately I can't think of a single 100 watt solid state amplifier that I would actually want to own and then I can't think of one that would work with the metal tweeter in the KEF.

So we go to tubes but then the powerful tube amps are push pull which are not otherworldly different from a lot of Solid State amplifiers. I certainly would not be buying anything unheard from Rogue or LM. I like the 211 - the 216IA is good but I like the sound of the 211 better - the 216 is probably the more accurate amplifier technically and will do hi-fi things better but for me it would be an amp I would have to buy a bunch of tubes for to get to sound the way I want. PSVANE grey bottle tubes would be the first thing I would put in. But that adds to the price.

Rogue offers a lot for the money...and at least with tubes you can somewhat tailor the sound via changing the tubes. So if you want a darker sound buy an appropriate tube.

Ultimately I think if you want to go SET or low powered buy an appropriate loudspeaker and dump the KEFs. If you must keep the KEFs and your rooms i medium and you want to play reasonably loud you need to be looking at 100watts of something. In a small room the 219IA is more than fine but anything bigger and my amp will be in the red all the time. Even in my small room I have red lined the meters to 50 watts double it's rated power. The KEF's are hogs.

I almost traded them ion the other day for second hand Reference 3a MM De Capos - I'd have paid $200 difference. I am still strongly considering it.

 

[mcanaday]

Well no easy answers, then, but I certainly am getting an education. Unfortunately, the dealer near me who carries both Kef and Line Magnetic doesn't keep the 501 on the floor, so no luck there. I think it is going to be hard to hear them together. (I have been able to hear the Cronus Magnum with the Kefs and that sounded nice, I thought, but it would be useful of course to be able to compare to LM.) I'll keep looking around. In the meantime, I can't thank you enough, RGA, for such a thoughtful and generous reply. And thanks too to OntheEllipse for your thoughts... cheers!

 

[johnvb]

And anyone else who wants to chime in! with many thanks!

I will be interested to hear of your comparison between Rogue's class D and tube amp on the LS50s.

Right now running dual Crown XLS1500s (not bridged, so 'only' slightly over 500 wpc @ 4ohms) on mine, and the sound is surprising great. Especially for the $$$. Using a iTube stage after the DAC, going to a solid state high gain multichannel pre.

Thought about upgrading to Rogue's Atlas Magnum power amp myself, when the funds are available. Then moving the Crowns to the HT. But I could live with the setup I have now for quite a bit, becoming a fan of Class D.

 

[beatcomber]

I just switched from the 8-ohm taps on my Fisher 400 tube receiver (restomodded by audiodon) to the 4-ohm taps, and lemme tell you, the improvement is not subtle.

On 8 ohms' impedance, it had a sort of soft, pillowy sound, and also rather dark. On 4 ohms, it has a much more dynamic and crisp sound, without that soft top end.

Awesome!

 

[beatcomber]

And another thing... Imaging was good before, but it now has become scary good!

 

[mcanaday]

Hi johnvb and beatcomber. Great that you have found such good combinations! For myself, I ended up not going with Rogue or Line Magnetic! I wasn't able to hear a LM 501 with the speakers, and that made me too nervous. And then I started to think about practicalities: The LM is pretty heavy and there is the heat factor etc. So I finally decided on a Vinnie Rossi LIO -- in part because I could do a 30 day home demo; in part the tubestage seemed the best of both worlds. It is also relatively compact and a modular design so I can upgrade as I go. And the novel power supply gets you off the power grid. It sounds gorgeous and I am really happy with my choice. (But I also think the Rogue and the LM would be excellent choices--just less practical in my set up.) Enjoy! Margot

 

[avanti1960]

glad you found a nice amp. i heard the lio and it sounded amazing.
i'm looking at the LS50s and tube power is the only way to go from what i have listened to.
just a basic 20WPC all tube integrated made the LS50s sound 10X as good as they did with a Parasound SS system.
Strongly considering the Cronus Magnum II and will try both the 4 and 8 ohm speaker taps

 

[mcanaday]

Will be interested to hear what you think. Seems to be a combination many people love!

 

[Hawkeye83]

I've got mine running on a "lowly" Peachtree Decco2 (40WPC) and I think they sound pretty good! Would love to hear them on tubes though. I've yet to own a tube amp, or anything tube, other than a tube tuner I've got. Something to look forward to...will probably try out a Fisher receiver one of these days...