Tube amp advice

I am thinking of trying out tube amps. My current amps are Kharmas (MP150). My speakers are Wilson Benesch and they are not an easy load (sensitivity is 86 db, impedence 6 ohms).

So, it would seem I will need a pretty perky tube amp. Some research has shown me that the EAR 890 and the Rogue M-150's are good values in my general price range, are well regarded, and are powerful enough to drive my speakers effectively.

Any thoughts on how these two amps compare? Any thoughts on other amps that might work well?

Thanks in advance.

My Dynaudio Focus 220s are a similar load. I drive them with the 60 watt TAD-60. My listening room is is 12x14 so I do not have to crank it up to fill the room. I was not sure when I bought the amp that it would drive the Dynaudios, but it does just fine. I can tell you I am very pleased with the TAD. The build quality is exceptional and it sounds wonderful. However, I would love to have the TAD mono block tube amps. There is a NOS pair for sale here. I wish I could afford them right now but with a daughter in college it aint gonna happen. These could be your ticket. I have no affiliation with the seller.
My Almarro A318B amp is a very high current amp that will drive the Gallo 3.1 with no problem. Here is a 6moons review on it.
Hey guys thanks for the advice. Much appreciated. I forgot to mention that I am also interested in balanced inputs.

There's a fair amount of misunderstanding about tube amps and what distinguishes a good one from everything else. To drive speakers that feature low impedences in the bass, a tube amp's wattage rating is largely irrelevant - what matters is the quality of its output transformers, which convert voltage to current, and how stiff (robust) its power supplies are. Really good output transformers are extremely expensive and heavy, and stiff power supplies are very heavy. Thus, there's an old adage, which is generally quite true, that the heavier and more expensive a tube amp is, the better it's going to sound on hard-to-drive speakers. To put things in perspective, 100 watt/channel tube amps tend to weigh 50 lbs. to 80 lbs. What is generally recognized by knowledgeable audiophiles as the most "powerful" regular production tube amp, the CAT monoblocks, put out 100 or 200 watts/channel (depending upon the model), but weigh 192 lbs. per chassis and cost $30k to $50k (depending upon the model). In short, most tube amps, including those that the magazines have concluded are "good", really can't drive tough-to-drive speakers like Wilsons (or anything else that drops below 4 Ohms in the bass).

An amp that was well built and is available for very reasonable prices used is the Sonic Frontiers Power 2 (it features balanced inputs, but is single-ended). If you can go up to $3k or $4k, the BAT VK-75 SE is a good amp that is fully differential balanced. Also for $4K is the VAC 70/70 (Mk. III or Signature), which is an amp I have owned for ten years. It is a tremendous amp that does it all (fully point-to-point wired and fully Class A biased, zero feedback, directly heated triode 300B output tubes, auto-biasing, sentry circuit to automatically shut down out-of-spec tubes, and totally dual-mono all the way down to separate power cords and on/off switches - the amp will drive 1 Ohm loads), but it does not have balanced inputs - I run a balanced cable to it from my balanced preamp, and use Neutrik convertors on its single-ended inputs.

My advice is to stay away from tube amps for low impedance speakers unless you are prepared to spend what it takes to get one that can do the job. Unfortunately, most tube amps manufactured these days cannot.

Good luck.
I drive my JM Labs Focal Electra 936s with Amps that weigh 80 lbs a piece and are rated at 75- 78 WPC. The Focals are rated at a nominal 8 ohm impedence but have a 3.8 ohm min. impedence.
I agree with Raquel the output trannys must be big and heavy, to do the job right, the combined weight is about 160 lbs. They do a truly fantastic job and are very under rated, they are Opera Consonance Cyber 800 mono blocks. In fact they got a Blue Moon Award on 6 Moons, I encourage you to read the review. They List for $3995 new but you can usually get a deal on them. Used they sell for less than half that if you can find them.
E-mail me for a vendor who I know will give you a good price. No affiliation etc. But keep an open mind and ear these really punch way above their weight. (unitentional pun)
Manley Snapper can probably do it; and fully balanced.
Hi Dan,
That post by Raquel is absolutely correct regarding the importance of high quaility transformers and power supplies, they matter greatly. His suggestion of the VAC 70/70 amplifier is spot on, this was one great all time tube amp. It used 300b tubes in a push pull circoit and simply sounds wonderderful. keep in mind this is a directly heated triode tube(DHT) and not a pentode tube like the two amps you mentioned. The main downside to the VAC amp is the tube replacement cost for multiple good quaility 300bs(they do have a long life span however) but man oh man the sound! I do believe that the EAR 890 amp would drive your speakers very well, it does have very good transformers and power supply, just a different sound using the KT88 pentode rather than DHT tubes.
There is a Music Reference RM-200 on Audiogon right now which is known to drive difficult loads well. It's no CAT, and it's not 200 lbs, but 90 seems like a good start. I haven't heard the RM-200 myslf, but I do own its smaller cousin, the RM-10.
This is very helpful. Thanks everyone. Part of the reason I like the Kharmas is their small size. Not sure I'm ready to go back to something massive. I really do appreciate the suggestions and will check them out.
I use the Rogue M-180 mono blocks to drive Martin Logan Summits that have a minimum impedence of 1 ohm at 20khz and they sound very good to me. I think they also pass the weight test at 55 pound per amp. Made in USA to boot.
My experience is that once I tried a tube amp, I have been unable to return to (enjoy) solid state amps.
A final comment - one reason older tube amps are so desirable is that the output transformers in tube amps take forever - years - to fully break in. This is one large advantage five to ten year old amps have over new ones.

Although beside the point, another thing to remember is that the tubes are the circuit in a tube amp - if you retube the amp, you essentially have a new amp, this providing a gigantic advantage over solid-state amps for longevity (some high-profile solid-state amps become door stops if they ever lose an output transistor because the transistors have gone out of production - this won't happen to a tube amp that uses output tubes common in the tens of thousands of tubed guitar amps that are sold each year, e.g., EL-34's, 6L6, 6V6, 6550, etc., or that use a classic triode like the 300B).

A really good tube amp is like a Porsche 911 - a bit tricky to operate and conceptually not the most up-to-date, but capable of extreme performance and it will be around when most everything else is long gone.
Will the Ayon Triton do the trick? I sure hope so. I have one. I was considering buying Revel Ultima Salon 2's, rated at 86.4db into 6 ohms but was told 100 watts won't do the trick. I'm understanding it's current and not watts (thanks Raquel) so maybe it's still doable. My second choice for speakers would be the Verity Parsifal Ovations at 89db into 8 ohms. Is the Verity easier to drive since it's going into 8 0hms?
"one reason older tube amps are so desirable is that the output transformers in tube amps take forever - years - to fully break in. This is one large advantage five to ten year old amps have over new ones."

It's not unusual for me to be last on the team to find out, but is this a well established fact?
01-05-11: Phaelon
"one reason older tube amps are so desirable is that the output transformers in tube amps take forever - years - to fully break in. This is one large advantage five to ten year old amps have over new ones."

It's not unusual for me to be last on the team to find out, but is this a well established fact?
Phaelon (Threads | Answers | This Thread)<<

Only if you forget to take them out of the freezer.
Thanks for the additioanal advice all. Lots to think about.

I intended to make a comment in response to your post, but forgot. I ran the original Revel Salons for three years and at least with respect to the original Salon, believe that the standard advice about powering the speaker at the time, which was that it sounded best with massive amplification, was dead wrong. The first and current versions of the Salons both use high-order crossovers and proprietary drivers that can handle a lot of power - one of my dealers had a customer that ran a pair of the original Salons with 1,200 watt monoblocks and they indeed can go extremely loud, cleanly. But this misses a crucial point, which is that the Salons are also very much a finesse speaker that comes a lot closer than many state-of-the-art speakers do at accurately reproducing the sound of unamplified acoustic instruments (i.e., most of the music in the classical and jazz genres). If you put a typical high-powered amp on Salons, the global feedback used to stabilize the circuits in such amps is clearly audible. If you search the threads, you'll see a lot of complaints about the speaker sounding lifeless and two-dimensional - that's because they tend to be demo'd with high-powered solid-state amps, often Levinson 300 series amps, which all use global feedback.

In short, the original Salons actually sound best, if the realistic reproduction of musical instruments is your goal (as opposed to shaking the neighborhood with home theater content), with lower powered, 100 to 150 watt amps that feature fewer output devices (i.e., fewer output tubes or transistors) and preferably, little or no global feedback - these speakers are very revealing and transparent like few others, and you really can hear what the upstream components are doing. Perhaps because the original version of the Salons can now be found used for $4,500 used, people think that they can be used with any old equipment - they can't. 100 high-quality tube or solid-state watts really lets them play music. If you want to reproduce dinosaurs stomping, and they can certainly do that very well, too, then run them with huge solid-state monoblocks, but if you want music, put a high-quality, zero-feedback tube amp on them - they can be really good speakers. As for the Salon 2, I don't have any meaningful time with them, but would imagine that they're even more demanding of quality amplification given their beryllium tweeters.

Looks like there's still hope. It's worth a shot anyway. Someone else here (Ral) suggested giving the Salon 2's a listen with the Triton before going for my second speaker option. A point he brought up though is that the speakers might go to 3.7 ohms at lower frequencies despite a 6 ohm nominal rating and that this might be a problem. If this turns out to be true, what would be the result of the 'problem'?

These days, a dip to 3.7 Ohms in the bass is almost considered moderate given how many speakers drop below 3 Ohms (and even down to 2 or below). To answer your question, the problem with most tube amps driving speakers featuring large impedance dips in the bass is that the amp can't deliver enough current to control the woofers - bass response is flabby and ill-defined.

A real-world example is all of the people out there trying to drive WattPuppies with $4,000 tube amps and getting Sony rack-system bass. Perhaps the best example is the CAT JL-1's mentioned in one of my previous posts, which were the original CAT monoblocks from the late 90's and only rated at 100 watts per channel - they were designed to drive the very inefficient MBL 101B, a speaker which also features wild impedance swings. The output transformer alone in these 192 lb. amps weighs 55 lbs. The bass performance of those amps sounds like a 500 watt Krell. Here is an interesting thread that discusses the CAT amps at length:

My best hi-fi buddy ran the CAT JL-1 Limited Edition amps (the LE's were $50,000, featuring incredible parts quality) for a few years and they are indeed the king of the jungle. With big symphonic music, a high quality DSD recording, and high-output speakers, they will knock you through the listening room wall on peaks.

I do not know how the Triton would perform with low impedance speakers, but it uses KT88 output tubes, which are difficult to make, the result being frequent tube failure. With KT-88's, it's all the more important to have a knowledgeable, reputable supplier.
I have used speakers that are very close to yours(85db, 6ohms.) The Harbeth SHL5's and now the M40.1's. The Manley Snappers were killer good with the smaller SHL5, but IMO not enough juice for the bigger M40.1. The VTL's have worked out great for me with the M40.1. I would put both on your list if looking for nice, affordable and very good sounding tube amps.

Thanks for the link on the CAT amps...good info.
As for the KT88 output tubes, am I able to 'upgrade' to better, less prone to fail tubes. If not, guess I'll be stocking up.