Leben cs300xs & Integrated amp demos: to tube or not to tube?

I've read/heard an awful of good stuff about this amplifier, anyone have one or heard one?
I'm seriously considering one and wondering how it would mate with my Harbeth M30.1s.
I'm demoing Sugden amplifiers right now, which are generating a tremendous amount of happiness inside of me, but this is a big purchase decision and I just can't home demo all the amps I want to at this price point in Vancouver.
Thanks in advance my friends.

–R

 

I've definitely heard them (not with Harbeths). They're really nice, but IMO 15W/Channel is just not enough for the M30.1's...

 

Jeff Day pairs up a CS-600 with Harbeth Super HL5s and said they were an excellent match, however it has 2x the power of the Cs-300sx. Although I think (not positively sure) I read somewhere he traded his Leben stuff in for vintage McIntosh gear).

I would try out a Decware Torii MKII or IV before the Leben CS-300sx or CS-600 though. Torii = S.E.T. "even order harmonics" in a PushPull design. The MKIV has 2 sets of RCA inputs, volume and can be setup to use EL34, KT66, KT77, 6L6 or 350B tubes!

 

Thanks guys.

 

I have a CS300XS but would echo the others' comments about adequate power (I use them with 90.5 dB DeVore Fidelity Gibbon 88 speakers).

In researching the Leben, I read through the massive CS300XS thread at Head-Fi, some posts at Harbeth User Group, and as many online reviews as possible. My decision, though, was different from your decision since I was considering new speakers at the same time. I eventually chose the Leben/DeVore combination because I'd be using them a smaller room (13.75 feet by 13.75 feet), I already had a sub (REL T2) to cover for any lack of bass, and figured my past volume levels wouldn't strain them too much.

My impressions so far after 3 months of use:

-The Leben replaced a 100 watt into 4 ohm McIntosh receiver (MAC 4100). I did try the CS300XS with my old speakers (Epos ELS-303--87dB sensitivity--4 ohms) before the DeVores arrived and found the soundstage was wider with a bit more clarity [this impression was with the sub in place as before and stock tubes in the Leben]. The CS300XS does have an 8 ohm/6 ohm/4 ohm output control in the back for different speaker impedances.

-After replacing the Epos speakers with the DeVores, the soundstage and imaging with the Leben went to another level: horizontally (and depending on the mix/mastering) some instruments sounded like they were from surround speakers, while the front-to-back layering was the clearest I've been able to spot instruments (for instance, on Grant Green's Matador, Elvin Jones' drums were more in the rear of the right side, while Billy Higgins' drums on Hank Mobley's Far Away Lands was more upfront). The Leben/DeVore combination has given my old Rega Apollo CD player and P25 turntable a new lease on life. However...

-With the stock tubes in place, I felt that too many recordings had a bit of harshness or glare. I have since changed the driver tubes and power tubes and found that changing the driver tubes is probably more important. The combinations I've enjoyed the most:

*My dealer recommended the reissue Gold Lion 12AX7/ECC 83/ gold pins for the driver tubes and New Old Stock Mullard EL84s for power tubes. I currently use this combination and find it's the best balance of strong bass, slightly warm tone, and open mids/highs.

*Driver: Sylvania Triple Mica Black Plate 5751, Power: Tungsram E84L Similar tone to the Gold Lion/Mullard combination but bass was stronger and imaging more focused. I
have not yet tried the Sylvanias with the Mullards.

*Driver: reissue Gold Lion 12AX7, Power: Amperex D-Getter EL84 Best mids/highs, but slightly weaker bass performance.

-Conclusion about the Leben, tube rolling, and transparency: you can tailor the sound greatly through tube rolling, and if pressed, you could probably replace the stock Sovtek driver tubes with reissue Gold Lions and get decent performance just from that one change.

-Depending on the types of music you enjoy, the Leben may be enough power for your M 30.1s. It could probably do well enough on jazz without a sub or the bass boost feature set to +3 dB, but since I also run it with hip hop, dub reggae, and metal, I find myself either using the bass boost or turning on my REL T2 with the Leben. The setup gets loud enough for me around 10 o' clock on the volume control.

-I think Art Dudley articulated what I have experienced with the CS300XS in his review of the original CS300:

-In conclusion, I think if you're considering the CS300XS in addition to the Sugden, an in-store demo with your speakers or ideally a home demo would let you know if the Leben could handle your power needs. If you find the sound a bit on the bright/harsh side, I would attribute that brightness/harshness to the stock tubes moreso than the unit itself.

Good luck with your search

 

I haven't heard the c300x but just looking at the specs -- those Harbeths seem to be pretty inefficient at 85 dB/w/m and that amp, rated at 15W but according to it's specs at .7% distortion at 10 watts, looks like a less than ideal match for those speakers if you're interested in listening to anything with big dynamic swings (or probably loud bass) at decent volumes. Probably not the combination to play "Night on Bald Mountain" on really loud, or loud rock, but might be okay with baroque solo violin partitas and some more decorous jazz like '50s Brubeck or something.

 

I think you owe it to yourself to listen to a tube amp. If you can't get the Leben in, any respectable tube amp with 40-50 watts is probably the sweet spot. Remember that the actual tubes are probably as important as the circuit design, and tube amps can chnge their sound substantially based on what you plug in, so take any audition as a chance to hear tubes drive your speakers, but remember that if you like the general sound, it can be tweaked over time.

 

Yes, I had owned CS600... and sold it. I mentioned before, but Leben is not popular here at all.

 

Many thanks for this detailed response, I appreciate it.
Cheers my friend!

 

Also worth noting perhaps just based on specs, you have a 6 ohm nominal impedance speaker. I don't know what the impedance curve of the speaker is but from either the 4 or 8 ohm taps on the amps OT, you may have less than maximum power transfer and some degree of headroom limiting, which, for a combo that's already a low power amp and inefficient speaker, makes it even less of an great match.

 

Hi Kazu,

Can you remind me again about your thoughts on the Leben? You ended up with the Sugden A21AL didn't you?

Many thanks!!!

 

A great point... I hadn't thought about that. The 600 would probably be a better fit if I was going to go Leben, but it's too dear ($5,700 CAN I think). I'd really like to demo some tubes, but there is just nothing for tubes in Vancouver in the $4,000 price range. Perhaps a tubed phono-pre to match up with the Sugden? I must admit, I love the Sugden sound, I just want to be able to compare it to more amps before I drop that much coin.

 

The valve world seems in a bit of upheaval at the moment. The number of manufacturers of new valves is pretty low. On the other hand, you have new designs—KT120 and KT150. If you read the buzz on the KT150 it is VERY GOOD. No doubt, there are some impressive new designs in the works at the moment. Also consider, that with a pre or integrated, the cost of NOS valves and any experimentation is going to be expensive.

I was recently forced to upgrade, and bought my valve integrated used for $1,100 ($2,000 retail). I have easily put another $600 in valves into the unit to shape the sound until I was happy. Now that you have a nice phono stage, you might look for a similar sort of integrated used, knowing you could sell it if it was not as good a match. A more adventurous direction might be the Eastern Electric mono blocks. They have a somewhat unique valve and deliver a nice 160 watts of tube power. I can tell you that the transformers are very good, and the designer uses both point to point and circuit board designs. He sources his transformer cores from Japan. I think these products offer incredible value, and although the M88 has not been reviewed by a major publication, I think some of the reactions by users on other boards offer deeper insight—specifically that you would need to move above the $5,000 target to get better sound. Any very good push-pull design is going to give you a glimpse, and I did notice a used M88 going for $800 recently. That gives you some room to buy new valves.

What Chervokas says is very true about the impedance. Believe me, I lived with a Class A 30-watt amp driving a 90db speaker (real world 87db) that dipped down to 6 ohms for 20 years. There is never a perfect impedance match, but I always went back to the 4 ohm taps, which produced the best sound but didn’t fully untilize the power the amp had. You want a little extra power so your amp doesn’t get tired driving @ 90 plus db.

Mark my words, there are going to be some KT150 amps coming out that will best the sonics of older power tubes and easily deliver 60 plus watts of good power for less than $5,000, if you can wait. I am very much enjoying the KT120 now, retrofitted to a basic KT88 amp.

 

I'm loathe to get into mono blocks, because I want to keep the system simple and uncluttered as my fiancé and kids (when they are staying with us) all share the living room and the system is already taking up a fair amount of square footage (those Harbeths like being away from the walls).
A dedicated room is out of the question (seen housing prices in Vancouver? $800,000+ for a two-bedroom house in my neighbourhood these days), so even when we buy within the next year or so, we will be limited to a largish condo, most likely concrete.
Also, since I have just a stand-alone phono stage, with mono blocks I have to get a preamplifier as well; more boxes, more cables.
Not what I'm after, hence the idea that maybe a tubed phono stage might give me a slightly more euphonic sound – a nice balance to the SS integrated amp?
Thoughts?

 

I believe that a very quiet solid state phono pre with valve pre and valve power tubes is probably the best approach. I have never heard valve-sweetened solid state do the same thing. I think the power tubes preserve harmonics and keep a coherency and space between the sounds, which is what you want getting to your speakers. Class A will give that unlimited current that gives you the grip. That makes it sound very realistic. When you add valve output and preserve the harmonic structure you get the grip with a very palpable sense of space and air, as they say.

Other side of the coin, I am in that camp that believes you need a coherent speaker to take full advantage of valves. Harbeth and most other reputable makers don’t put as much stock in coherency, and I fully understand their perspective. Which is to say, if you have a driver wired out of phase, unless the time domain has been shifted to bring the waveforms into time alignment, that harmonic coherency that you get with SET and to a lesser degree with some push-pull amps may not be fully utilized.

EE seems to make very good preamps on their integrateds. Every reviewer switches in a different pre and ends up using the internal on the M88. A great preamp in an integrated is the thing.

Too many tubes and it gets very confusing as to what is influencing what.

It may be that Class A SS is the best match for the Harbeths. God knows tubes/valves are sad when they are pushed too hard, and complex crossovers gobble up that early, good power amps put out, which is probably why Class A sounds so good in your application—plenty of good power.

 

Someone was just telling be about the high prices in Vancouver...
IMO, I like Harbeths with SS amps. The speakers are smooth enough by design, euphonic amps are just too much of a good thing... On the other hand, I've heard speakers that need some chilling out with a tube amp, etc... But that doesn't pertain to Harbeths...

 

My Sutherland Ph3D is very, very quiet. The quietest I've ever heard, so I hear what you are saying regarding the order of tube/SS in the power/pre chain.
But wouldn't a transparent tubed phono-pre (EAR 834P MM/MC is one that jumps to mind, or something similar) add that extra touch of euphonic sound I'm looking for?
Looking forward to replies!

 

I honestly believe there is more to tubes than euphony and coloration, and the full deal is having output tubes. Better to hear it and then back away than get a toe in the water and believe you've been swimming in the ocean. Being able to switch in KT88s, 6550s or KT120s and change the whole sound of the amp is pretty amazing. The stock KT88s sound extremely neutral with only a depth of soundstage to give them away. The 6550s have lots of space and timbre and micro-detail in the mids and lean, tight bass. The KT120s are very full yet controlled in the bass with softer, lush mids and nice top end extension (as best I can hear it with my rolled off speakers). Being able to move to a new house, set up the kit, and then fine tune the sound without shipping a bunch of new amps in is priceless. I may have new speakers at some point, and I can tune them and fit them into my room having the advantage of being able to roll in different tubes.

My working theory is that there is some illusion of spatial information created in the high-frequency areas beyond the audible range, and tubes keep this information together and in some cases exaggerate the effect. I got hooked on this sound early.

 

I did note that the CS300XS has an output control switch in its rear panel: you can select 8 ohms or 6 ohms or 4 ohms to match your speakers' output impedance.

Still, I agree with others' assessment that you would want a demo with the Leben: it may (or may not) be able to handle your preferred music.

 

From a knowledgeable friend:

"Valve amps produce very little current or in some cases, none at all. What I’m saying is your Sugden A21 has bags’ more current than a humble valve integrated. Watts are needed for insensitive speakers and current delivery is vital for inefficient speakers."

This I think is a very important point, which is why I think that the relatively low wattage of the two Sugdens is not an issue with my P3ESRs or my M30.1s.
Sugden touts the high current available from both the A21AL and SE as a major source of it's ability to cope with inefficient speaker loads. I believe the 6Moons review said something along the lines of "more things to more people" in describing the difference between the AL and SE due to the almost doubling of the available current in the SE amp over the AL.

 

Excellent catch. I suspect the device is still under powered given the speaker's efficiency, but w/ a 6 ohm tap off the OT I guess there wouldn't be a further power and headroom loss from a mismatch.

 

That is why the output transformers are soooo important on a tube amp, so 40 watts ends up weighing 62 lbs.

 

I have listened to a Leben integrated amp, and I believe it was the 300. I recall the sonics as being very smooth and tube like in all of the good ways. Background was quiet and FR extended, with great imageing.

In following the Leben brand and reading many of the reviews, their approach strikes me as having taken a vintage amp and then carefully rebuilding it with all new parts. Their house sound is a great balance between vintage and new....and would be perfect for someone who wants vintage tube equipment but does not want to worry about long term reliability or the tradeoffs involved in rebuilding a vintage piece. In fact, someone posted that the CX300 was like someone creating a modern version of the Eico HF81.

 

I believe the basic tube circuits are pretty well established. The preamp and the transformers are what to focus on, IMO.

 

Which why it's a bit odd to see such an "old school" circuit (paraphase splitter) used in a modern amplifier.

jeff