KEF LS50 and integrated tube amp

I personally don't think that anyone buying LS50s is choosing them for massive church organ pieces, of musicbut for the other 99%, yeah, they do just fine in a normal-sized room (think 12x12ish), especially if you mated a REL to them.

 

Can you elaborate a little more on the ratings difference. In dealing with guitar amps, it was certainly my experience that tube and SS watt specifications where not giving consistent perceived loudness.

 

I do have a Martin Logan sub, is there any advice on how to integrate the LS50s with a sub.....

 

Run the LS50's full range and only use the sub to extend the bass below 50 Hz.

 

Ive had many valve amps ,they can be fun,and many love the classic brit amps from the 50's and 60s.
However they need continuous front line maintenance and attention which in the day of the correctly implemented chip, seems a bit pointless
Valves really need to be left on and regularly replaced otherwise, as they age they burble and fart at low levels and generally are inconsistent
I still love em in gtr amps though,their distortions really can be euphonic
As for small speakers not producing LF this can be a revealation
The overhung cone break up associated with large drivers obscures detail
Small drivers reveal much more, the KEF 50 are exceptional

 

They shouldn’t. This is one of the tunes I have on my test CD that I use to demo. Massed vocals on one end and low, resonant bass on the other. I’ve listened to this track on the LS50s and the R300s, near field.

 

Some manufacturers such as Primaluna have made important strides in improving the reliability of tube amplification. The Rogue Audio type tube amps have a pretty neutral voicing, but some coloration due to the frequency response characteristics. The Stereophile article on the Primaluna Prologue Premium pointed that out even though the measurements still show significant deviation from a simple wire transmission model. Of course, guitar amps sound great precisely because they introduce distortion into the signal, which is critical for the electric guitar sound, but is a different design goal.

I listened to a Primaluna 40W and a Denon 125W SS through the LS50s at a local dealer the other day. I was surprised to hear that the mid-bass was tighter than the Denon. Perhaps they tuned the frequency response of the tube amp to be more pronounced--or perhaps modern hifi amp designs like their guitar amps counterparts are getting more sophisticated at meeting their design goals. That experience seems to be common by a number of posts.

Nevertheless, there seems to be a disconnect between subjective measurements, which Robert Harley at Absolute Sound believes is paramount, and objective measurements of amplifier performance used in evaluation and design. Self-delusion or the subtleties of psycho-acoustics?

 

Trust your ears... and your wallet.

 

As nice as the LS 50's are they are in no way the answer for all monitoring or loudspeaker discussions. If you add two subs you can get pretty decent near the real deal but in the end bigger and more pricely speakers with more chassis and larger volumes will do a better job. Even in the price range of compact or mini monitors you can get speakers, that are better in some regards. So expecting them to transfer the LSO into your living room or having the impression there is a Live Rock concert taking place is unrealistic. Same goes for the size of the room you want hem to play in. I'd say up to 15 square meters they are spot on. 20 are manageable with sub-woofers.
That figure is more important than WATTS. Watts don't really tell you the whole story it is volts, current and how stable the watts are if doubled down from 8 to 4 to 2 Ohm. If your amp is stable down to 2 Ohm and delivers enough clean watts for longer periods you are close to the safe point. The other important figure are dynamic peaks. The size and quality of the power supply matters - transformers in Tube amps. Still imo there are better speakers for tube amps than the LS 50.
Regarding Rock at hogher levels THIN LIZZY LVE sounded brilliant yesterday on my PRIMARE LS 50 combo (even without a sub) but in a room under 15 square meters and only 2 meters ) 6 feet from the speakers..

 

I'd equate it to a torque rating on a car engine. You can have two engines both rated at 300 bhp. One might have 225 lb/ft of torque, the other might have 280...there will be a big difference in the responsiveness of the engine. Generally, a better quality/bigger transformer in the amp equals more torque on the bass frequencies.

As you said, the same holds true with guitar amps. I had a 100 watt Line 6 digital amp that I used at home. Sounded good at home volume. Took it to band practice and couldn't get it to cut through the mix no matter how high I turned it up. Replaced with an 18W Marshall clone and could hear myself again, without totally cranking it...

 

Line 6 amps do not sound good, they rely on emulation,Roland sound wonderful and also emulate, but better.
Hi Watt amps did sound louder than most other valve amps with similar topography ,only because they used pots with different linear travel, all the gain was in the first quarter turn......
IMHO small gtr amps sound the best, the Vox AC15 @ 15watts and the Fender Bluesman jnr @ 12w sound delicious.
For hifi its very different ,we just need a wire with gain ,and plenty of it.

 

To my ears, (as I previously wrote on my amplifier comparison thread) the Audio Note Oto SE at 10w had truer timbral accuracy (and many other notable traits) than the Sugden A21SE (30w). Neither is a high-powered amp, but both have very large transformers, the Oto has two massive ones, and it is this hefty voltage capability that IMHO, allows them to drive speakers which aren't nessessarily efficient, but present an easy load to the amplifier. My previous Harbeth P3ESRs and current M30.1s being a good example of this.

 

Its not just volts ,its current too.
10 w might do it for you, but that would not cover real musical dynamics uncompressed.

 

Is this right? I didn't know that.

 

After living with low watt tube amps for a couple of years now I have to agree with ROLO46.

IMO 10 watts is not enough to cover a dynamic range of music on a speaker below 92dB efficiency after a certain volume is reached ~ especially when multi drivers and crossovers are introduced within the mix. It might sound good and accurate at lower volumes (even the bass may sound great), but if realistic volumes are desired (i.e. you ever get the urge to pump it up on occasion) it will distort out very easily.

This is explained in good detail by Steve Deckert within his paper Understanding "useable power". A quick quote from Steve's paper:

<snip>

Dynamics are greater on low power tube amps matched with high efficiency speakers than you'll be able to get from a high power amp on low efficiency speakers - aka the hi-fi industry. In a quiet room with a low power amp and speakers of 94dB or higher efficiency you can expect around 30 dB of dynamic range in the first watt. (NOTE: It takes a doubling of power to increase the volume by 3dB). When you add a second watt of power you increase the dynamic range by only 3 more dB. If you double the power again to 4 watts you'll gain another 3dB and 8 watts gets you 3 more. By the time you keep doubling your power to get that additional 30db you require 1024 watts. So obviously power has a steep ramp of diminishing returns. a 100 watt amp is only 3dB more power than a 50 watt amp, almost un-noticeable.

IF FIRST WATT SUCKS WHY CONTINUE

This has been my tag line in the forums for many years. But consider the fact that many big audiophile loudspeakers with multiple drivers and complex crossovers have not the ability to resolve the first watt at a usable volume level. This is because a portion of the first watt is lost in the crossover network before it ever reaches the drivers and because the drivers have too much moving mass to be heard with what's left. So for the mainstream hi-fi industry it all starts with the second watt - meaning that first 30 dB of dynamic range (music) is largely missing. It's not surprising many audiophiles build large high power systems up to 1000 watts trying to reach a dynamic range of 30 dB while at the same time some guy is sitting in his listening room getting more than 30dB out of a 2 watt amplifier with the appropriate speakers.

<snip>

The key within this paragraph is "appropriate speakers" for the amplifier load. Consider any type of speaker that is inefficient and/or multi-drivers with crossovers ~ that first watt is largely wasted so IMO you need a correct reserve of power to compensate/correlate for your speakers specifications if one wants an uncompressed sound and dynamic range at realistic volumes.

 

How heavy is the Audio Note? One issue I suppose is the peak current versus the average current. Quick dynamics need a lot of watts but for a short period of time. So, a 1 ms bass wack would require a different amount of energy than a massive pedal organ over 1s. 85 dB is not exactly quiet. Conversation at 3' is roughly 60-65 dB. Sustained 90 dB could cause hearing damage. So, in general, I thinks it's the transients--or dynamics where all that power is needed.....

 

26 lbs or so.

 

Those are great amps. Though I think the new contenders like Dr. Z, Two Rock, 65 Amps, are really producing great updates to those circuits.

 

In the case of the LS50, I think the inefficiency is derived from the damping rather than the crossover. I wonder if that would make a difference.....

 

The Oto SE is 38lbs...

One of the most important qualities of the Oto over any solid state amp I've heard so far is in its lightning speed in transients and it's ability to handle big dynamic swings. The Sugden A21SE was very, very good with speed and grunt, and the one area where I thought the Oto would fall short; it didn't, it bettered the Sugden by a noticeable margin. As it did against the Lavardin, the 125w Peachtree and the Sonneteer.

 

Interesting. It seems that if one had a CD of a simple snare hit every second, you could actually compare how these different amps responded. That would be something like an "impulse response" for the amp. That would be akin to a "large signal" square wave the J. Atkinson does in Stereophile reviews. If your subjective impression is right, then Oto should reproduce that snare hit better/faster than the other amps.....Do people do that?

 

The Primaluna and the Rogue Cronus Magnum are of a similar weight. I suspect they'd a pretty good job on the low frequencies as well--and produce a more neutral or modern sound relative to older amps.....

 

The Oto is the most transparent amp I've heard yet. I've often wondered if the people who comment on valve coloration or distortion have listened to a modern tube amp.

 

You claim its warm and lush but also fast and transparent,this would be some achievement
Any device with transformers is by nature softened
Any device with EL 84s (Mullard 5-10 amp) can be over driven with pleasant results
This was the base of UK Vox and Watkins guitar amps in the 60s
How modern is that?
We are talking about an amp to drive an accurate low efficiency driver with clarity and scale
Not a 10 watter that distorts pleasingly.
And costs $4k

 

I'm pretty sure that the Audio Note won't push the 4 EL 84's (or the pre amp tubes) into distortion at max volume. The Audio Note is, however, an amp which limits your speaker options and isn't one that I would reccomend to most.