Why not more on 845 SETs?

As a brand-new owner of a Bel Canto SETi40 int amp,(bought used) I was intrigued to see very little in the fora on the subject of 845 SET amps an A'gon. It seems that this provides the best of both worlds -adequate power to drive most moderately sensitive speakers- 40 Class A SET WPC with SET sound. What is the downside to this approach and why don't more of the SET groupies have higher powered amps, giving them much more latitude in speaker selection? I drive 4 ohm 87 db sensitivity Totem 1 Signatures quite adequately with this amp. Is it beacuse of transformer issues, difficulty in finding adequate designs, size or the feeling that this is not a true "SET sound"?
I would like to hear SET-owners' reasons, if possible.
Beats me. I have a pair of 845 SET monoblocks, designed and built by a friend, that will drive my Gallo Reference 3s to really stentorian volume levels. They replaced 140 wpc Conrad Johnson Premier 12s in my system because they simply blew away the CJs, which are certainly not bad amps. Dave
The 845 simply does not sound as good as a top notch SET 300b amplifier. In addition, if you want the best performance from 845 designs NOS tubes would be useful; they are priced at something like 1000/pr last time I looked? Sure, the manufacturers will tell you their design is optimized for the chinese tubes; the NOS will sound better but at a huge cost.

A 300b push/pull interstage coupled amplifier with top quality parts will make 16 to 20 watts and sound damn close to a well executed 300b SET. Main reason more 300b push/pulls are not sold is they are quite a bit more expensive. More power means bigger transformers; push/pull means more parts and more contruction time required (and a bigger chassis, usually) to put the push/pull together. More capacitors, resistors, wiring, twice as many 300b tubes (which raises cost anywhere from 200 to 2000 over a SET design depending on tube selection).

I would rather have a well designed 211 based push/pull amp that will run into class A2 and make a LOT of power. Or, a single ended 211 that will make in the mid 20s of power when pushed into class A2. The 845 cannot be driven into Class A2 is my understanding. The 211 is the tube that Mr Kondo selected for his original Ongaku amplifier in the late 80s.
C123666, what is class A2 operation?
Whoa there. Some of us like the sound of 845 SETs better than the 300Bs. In my case in a three-way comparison in my system between the CJ 12s, a modern SET 300B stereo amp, and the 845 SETs, the 845 was the clear SONIC winner. I know, YMMV and all that, but I've never heard a 300B amp -- not yet anyway -- that can compete with my amps. And certainly not a PP version.

The new 845B and 845M (I haven't heard these yet) tubes from SuperTNT are rewriting the book on what can be expected from new-production versions of these tubes. The 845Bs are $150/pr. There is absolutely no reason to invest in NOS 845s, IMHO. And even the best current production 845s are dirt cheap compared to 300Bs.
Where does one get a pair of 845B/Ms? The SuperTNT website doesn't allow you to get to check-out. Any local distributors?
Great thread, Denis!

My friend had a pair of ASL 1009 amps, featuring this tube, and of all the amps he has ever had, and he's had a lot of them (including his current Mesa Barons), this was far and away MY favorite. As good a sounding pair of amps as I have ever come across. Boy, did they sound HUGE, and lush, sweet, quiet, and detailed at the same time. A lot better built than I hear most people say.
I listened to many amps, ss and tube when looking for my new amp. I then tried an 845 SET and that was that. I love my 845. It's everything Trelja said. The resolution and dynamics are great. Wonderful 3D full bodied sound. Is it the best? Who knows. In my system it sure is. I look forward to what the 845b can do for it.

From all indications you have a great amp Springbok10. Enjoy!
Springbok, I got mine via the website but haven't been there lately. Don't think they have any distributors. Sorry I can't help.
The 845 can go into A2 if pushed with a strong driver, but most amps don't do that (incl. the bel canto I'd say), thus the so-called 40 watts is really more like 20-25. But that's fine, it's more than plenty. IMNSHO 845 sounds better than 300B by a pretty large margin. The tube is just one part of the sound anyway.

SuperTNT doesnt' have distributors over here yet. THey are probably sold out of the 845M fairly soon, they only had about 50 prs to sell in the first batch.

845B and M are nice, but NOS are still better (no surprise), so the reason to have NOS 845s has not disappeared. I know, I have plenty , and wrote reviews on both the 845M and 845B, posted here and on AA. NOS are expensive, $1000/pr is lower than what most will cost - usually $1300- $2000/pr is more like an accurate price of really great NOS guaranteeed 845s. Are NOS worth it? well, depends on your point of view. ;-)

BTW, A2 operation involves positive grid current, and driving a tube past the zero crossing from negative bias to positive bias. Doing this requires a very stout driver stage, and usually an interstage (often, step-down) transformer, sometimes called an IITC. However, any tube (and amp) that crosses over the zero point from A1 to A2 goes through a hysteresis (sp?) area of non-linear operation, aka Crossover Distortion. The best bet is to have an amp that runs in A2 all the time, if one is going to go the A2 route. Among commercial amps, not many do this. Wavac is the most common brand to run A2, but they cross over the zero point, and thus there is a compromise involved. Most SET amps run only or mainly in A1. The max power from an 845 in A1 is about 24-26watts, and that's flogging it at max ratings. Many tubes don't like to be caned that hard, so often the op point is a good bit lower for a margin of safety and tube life.

There's been a fair bit of discussion on 845s in the archives, search around a bit. IMNSHO it's the best DHT output tube available in current production.

Thanks, Ed, very informative. The SuperTNT website doesnt wok, fwiw.
A look forward to comparing the Jadis OR with the Bel Canto in my study system (Totem One Sigs, Cairn-Fogg v2 CDP, Acoustic Zen Double barrel S/C biwired, Empress i/cs, Kimber K14 and Signal Magic PCs) Both amps have distinctive and superior sonics and it would be fun to A/B them.
Tom(thetubeguy1954), Single Ended Triode Amps Group Moderator, where are you when we need you!
This is the 845 tube man...he has the Mastersound 845 Reference, parallel tube SET, 40 WPC, and absolutely is a fanatic about this amp. Maybe he'll pipe in here...
Ed...thanks for your input also.
My deHavilland Ios amp is the best amp I've ever heard. I'm wondering how
the dehavilland 845 products stack up against the other 845s? What speakers
work well with 845s? I'm using it with 88 db JMR Trentes and the Ios really
makes them sing unlike any other amp has been able to. I wonder how they
would work with more efficient speakers?

If one were to generalize what are the characteristics of the 845 and the 300b
in comparison? I would appreciate any descriptions here.
I own the older model deHavilland Aries 845 SET
amps-25 watts x 2. And a deHavilland Verve preamp paired with the Aries amps. Both units are 2 years old & bought used from Audiogon this past summer. Got the Verve preamp for 1/2 of retail price & the Aries amps for slightly less than 1/3 of retail price. Kara Chaffee & deHavilland make great sounding amps & preamps. Kara & deHavilland are also extremely helpful & friendly. They provide 1st class support & info even when you are not the original owner of one of their fine products. I am using the deHavilland combo with a pair of 1983 Klipsch Cornwalls. The previous original owner had the faceplates of the Aries amps & Verve preamp goldplated at a plating shop. He also had an oversized volume knob & source selector knob machined at a machine shop for the Verve preamp. The knobs were also goldplated. The sonics are great to my ears and are purty to look at as well to this Texan. The Aries are my favorite sonic flavor of the 4 amps I own. I have never heard a 300B SET amp or 300B PP amp so I
can't give an opinion about their sonics.

My other amps-factory assembled Welborne Labs
Moondog 2A3 SET monoblock amps with Ultimate parts upgrade paired with a factory assembled Welborne Labs Reveille 6SN7 tube preamp. And 1977 Klipsch Cornwalls with an upgraded new Type B crossover using Auricaps. DeanG a Klipsch Forum
member builds new crossovers for Klipsch speakers. The Auricaps are much better sounding than the motor run paper in oil caps that Klipsch used in their stock crossovers. Llano Phoenix CAS 300/VA2 mosfet/tube hybrid amp. The separate VA2 voltage section uses 6SN7,6SL7 & 12SN7 tubes. Currently using a pair of 12SX7 tubes in the VA2 voltage box. The Llano is paired with a Mcintosh C 38 preamp & JBL LX 55 speakers. Have a spare Mcintosh MC 7150 ss autoformer amp.

The deHavilland gear, the Welborne Labs gear & the Llano amp were all bought from here on Audiogon at excellent prices. Audiogon has been very very good to me!
Yes, I'd like to say a little bit, The 845 is the King of SETriode Tubes, Period! I've yet to hear a 300B, 45 or 2A3 that I would trade my Mastersound for. Please don't misunderstand me. I find the 45, 2A3 & 300B, all to be very musical, BUT the 845 is as musical, if not more musical, and has enough nut to drive real world speakers.

I've noticed one thing the fans of 300B, 2A3 or 45 never mention is... how much the triode tube's sound is directly influenced by the tube that drives it! So what we really have is a Gestalt type of thing, where the whole is greater than the sum of it's parts. Sure a 45, 845, 2A3 or 300B all has a characteristic sound, but so does the tube that drives it! The 300B driven by a 12AX7, the 300B driven by a 5687 etc all sound different. As does every tube we've mentioned.

Now to this day, to these ears the 845 driven by the 6900, is the closest thing to audio nirvana I've ever heard. The truth is, that in my Mastersound when the 6900 is replaced by a 5687, it's COMPLETELY changes the amps signature. It's still an incredible amp, but it's also completely different and NOT as musical. It seems only 845 tube lovers and designers talk about the influence of the driver tube. I know deHavilland talked quite a bit about the influence the driver tube they used on their 845 based amps and how this combination of 845 and driver tube is what made their amp so special.

I know this, "IF" you haven't heardan 845 tube driven by a 6900 tube, you have no idea what an 845 tube can do!

thetubeguy1954 (Tom Scata)
I personally think that the additional power in an 845 SET is not necessary. But, I guess that if someone wants to power some less-efficient multi-driver loudspeakers, it would be useful

What I would ask about this is, why would someone want to use a SET amp, and then drive inefficient multi-driver speakers with it? Perhaps I'm in a fog here, but I thought that the purpose of a SET amp was to provide coherence and purity of tone and harmonics. If you take the amp's output, and chop it up into bits and pieces in a phase-shifting passive crossover network which also causes other distortions, and eats up power and detail, use different drivers which inherently have different radiation source points, sonic characteristics, and dispersion patterns, and introduces odd-order harmonic distortion to a previously(primarily) even-order signal distortion profile, are we really getting what we wanted to get? I don't think so. But we will get what approximates a reasonably flat response test curve, as long as the output impedance is significantly enough below the speaker impedance curve to avoid reactive effects on the amp's response curve(not likely). What we really get with this kind of combination, is the relatively high even-order distortion profile of the amp, added to the even-order and also the easily discerned odd-order distortion profile of the multi-way speaker, making system distortion higher than necessary, and also in content(odd-order)which spreads out all over the spectrum, instead of primarily at the 2nd harmonic. In the case of lower efficiency, lower impedance(4 ohm) multi-driver speaker sytems, we can add the practically total loss of damping factor and cone control, and making the amp's freq response curve fluctuate with the speaker's reactive impedance curve, and add this to the inherently low internal damping ability of the less-efficient speakers, all causing bloat, flopping around cones, no tonal accuracy, and wild frequency response, added to all the other problems. Why someone would want to do this is beyond me, except maybe that they are after some deeper bass response at the significant expense of purity in the rest of the spectrum.

IMO, an efficient higher impedance single driver system is what is best with a SET amp. In that case a small 45, 2A3, or even 300B is fine.

If you want to say the 845 is better for deeper bass, fine, but I contend that it is not enough power for deep bass, and probably would require a powered subwoofer or powered woofer anyway for that purpose(another seam).

The issue is what is the goal of a SET system. Is it to simply provide a Class A amplification source, or is it to be something more than that? That's for the user to decide.

IMO, a SET amp can be much more than just a Class A amp. It can provide a distortion of predictable and less-invasive profile, that can be effectively utilized to work in a complementary fashion with certain loudspeakers, to create an overall system distortion profile of primarily easy-on-the-ear even-order harmonic distortion located in a fairly narrow range of the 2nd harmonic area, and nearly eliminating any of the problematic odd-order distortions which are so much more discernible to the ear that only extremely small amounts of it can be tolerated. Additionally, with the "certain"(single driver) speakers, it can deliver the sound from the amp without the inevitable multitude of problems associated with mainstream multi-driver speaker systems. Sure, single drivers have issues too, but delivering pure coherent high-detail sound with mostly even order distortion products at one area of the spectrum is not one of them.

My caution is thus, when you make a decision for a component, is it not a good idea to make the most of what it can do(as a whole), instead of trying to "shoe-horn" it into a more conventional role? I think so. The conventional wisdom of choosing a higher power amplifier, in order to make a wider selection of speakers possible to use(multi-driver), actually can lead you into a snafu which would not have been easily stepped-in with a lower power SET amplifier. The very fact that the low power SET amps practically forces you to use a high-efficiency single driver system(or horn) is actually a good thing, and not a limitation. The low power of the amp is actually almost "forcing" you to make the right decision. When higher power is available, then you can step right into the crap, unless you know what you're doing, and why you're doing it.

If you want to use an 845 SET, and you like it, that is fine, and there are some really good ones out there. However, there is alot more to a SET amp than how many watts it has, and whether it provides Class A amplification. With this type of amp, we can go beyond the mainstream, and get more than is typically available from more "normal" amplifier designs, if we study what they do and how they interact with various loudspeaker designs.

If you take a look on the web, at an article called "Why Single-ended amplifiers?"" by Audiopax's designer and engineer Eduardo de Lima(http://usuarios.uninet.com.br/~edelima/REASONS.htm), you can see his testing, graphs, and descriptions of the interactions that I mentioned above. He even shows how careful phase alignment of the speaker and amp output can work to reduce overall system distortion to below what any other type of package can produce, by using this type of combination.

I know this is a "radical" concept, but there can be more to things than easily meets the eye.
Twl, you seem to be writing off the use of SET amps with "conventional" speakers and I think this is needlessly restrictive. This is, or was, certainly the conventional wisdom and helped keep me from enjoying SETs for a long time. Then I discovered that certain speakers, despite their moderate sensitivity levels , were extremely SET friendly. Examples of such speakers from my personal experience are the ProAc Response 2, Response 3, Gallo Nucleus Ultimate, and Gallo Reference 3 (my current speakers). How can you tell which conventional speakers are going to be "SET friendly?" Well, you can start with something in the 88db sensitivity area whose impedance rarely or never dips below 8 ohms and whose crossover networks are very simple, but mostly you have to listen and see (or rather, hear). I'm sure glad I did. Dave
Perhaps a SET amp would perform best with a single driver speaker if one were looking for the simplest path, but that does not mean that it won't sound excellent through a dynamic multiple driver speaker. And with a single driver speaker you may not get much bass and I can tell you the bass the Ios/Trentes is deep and tight! I thought of this analogy: with some amps the Trentes are like a water skier being pulled by a sluggish boat; they just never get up and going. But with the 845-based Ios the Trentes get up, go and sing like a slalom skier on a glass-smooth lake at first light. Beauty, eloquence, dynamics.
The Gallo Nucleus Reference 2 (with full InSound/OmegaMikro upgrades, no crossovers, three 6.5inch Dynaudio drivers wired in parallel for 9ohm impedance, OmegaMikro wiring throughout, [?] 330 degree CDT tweeter, which more closely matches the dynamic drivers for radiation patters, and time aligned, 9ohm, 90dB/w/m) coupled to Viva Verona XL 845 tube amps (26wpc) has to be the best "all-rounc" performance I've heard from a SET system to date! This was for both full symphonic orchestral music as well as electronic "rock." It had a full, rich, immersive, and immediate sound.

I've heard a few other demos with 845 SETs. Each time I wanted to "not like the sound" as I _*knew*_ the sound should be less pure than a lower powered tube like a 45, 2a3, or 300b. But so far I haven't heard an flea powered system that I've like as much as the two 845 systems I've heard. I did go to MAF one year, but show conditions are only so good. I really could't draw conclusions in that environment. But without hearing a 845 SET, I would have though (on paper, with no first hand experience) exactly as Twl does. Maybe if I listened to more, properly set up flea powered systems I would think along the lines of Twl. But for no, I can't given what I've heard.

But I still covet that gallo/845 system. I was a good balance of positives with a healthy balance of negatives that I could tolerate long term. If only I could afford such a system!
Dave, not really "writing them off", but just mentioning that there can be some things that go beyond what is normally expected.

I'm not saying that single-driver speakers are for everybody, but I am saying that there is a certain synergy between them and SET amps that can be very productive if used properly. I know that single-drivers are frequency restricted mostly in the bottom end, and that alot of people cannot abide that restriction. However, when going to multi-drivers, some of the really good things about a SET amp are somewhat deteriorated, due to the things that happen with multi-drivers.

I really probably should have worded my post a little bit softer, but I do feel pretty strongly about this issue.

That said, I have no aversion to people using SET amps with multi-drivers themselves, if the users prefer that option. After all, it is what the individual prefers, and not me, which is the critical issue with each person's system.

I guess what I'm trying to say is that in my opinion, there is more to be gained by a good match in the amp/speaker combo with a low power SET/single-driver, than there is from having the higher power SET and using multi-driver speakers. In effect, having a low power SET with high-efficiency speakers will allow the same/similar SPL in the room as a higher power SET with lower efficiency speakers. So the listening level issue is somewhat moot. What's left is the sound quality, which IMO can be better by using a scenario as I outlined above, which can yield an overall system distortion profile that is audibly more palatable than other type while still yielding less signal losses(thus preserving the musical detail and life). Doubtless, some will disagree, and that's fine. This is just my point of view.

I don't expect everyone else to subscribe to this, and certainly am not suggesting everyone should. I'm simply pointing out an interesting factor that might be important to those trying to extract the most information out of their system, with the least objectionable results(from my point of view).

Your description of "SET friendly" speakers seems to be a good one. I'm sure that they all work fine with a moderate to high powered SET, and would sound great. I'm glad that you are enjoying the "SET experience", as I am.

As always, I'm just trying to make subjects for discussion here, and not making any "rules" or "judgments" about anyone else's system preferences or opinions.

Denis, please keep us in the loop over time as to how you find these new amplifiers. It is a rare audiophile who can really articulate what how something truly sounds, without adding their own personal biases, among other things. Over the past month, you have demonstrated an uncanny ability to actually hone in on the sound of a component. It will be exciting to hear how this component measures up for you.
Without first class transformers it won't matter how "good" the output tubes are. A well designed interstage coupled 300b or 211 SET amp sounds so much better than the capacitor coupled amps I've listened to I am sold on interstage tranny coupling.

The 300b SET interstage coupled amp being put together for me right now is so much better than my prior Audio Note Conqueror it is silly; another world. Parts cost on a four chassis 300b SET IS coupled is very expensive between 2000 and 4000 depending on transformers used (silver wound interstage run the price up about 2000).
Agreed, IT coupling is excellent. Cap coupling can be nice, but to be done right IMHO requires use of an excellent cap (read: russian teflon or better), AND requires grid chokes on both driver and output tube, and a good plate-load choke on driver tube. That done, it's basically like IT coupling in may ways (all the iron) except for the galvanic isolation (and any ratio/impedance change of course) of the IT.

Top-shelf iron (trannies, chokes, et al) are a must, in any case.

And transformer prices are going up as is anything made out of metal....Price a set of six transformers from Electraprint, or Lundahl, for a single ended interstage coupled amp, then figure in the cost of a truly inert/non resonant chassis and the other parts and you'll quickly see why most quality 300b amps start around 4000 to the sky.
This is a good thread.
- In general 845 SETs are very expensive to build.
- It generates a lot of heat. Not good in summer.
- My main speakers are BSL Type II (102db).
- I use Bel Canto SET40 in Winter. It kicks major butt.
- I use Moth Si2A3 in Summer. Very sweet.
- I use Music Reference RM-10 time to time. Very fast.
- I've used 45, 2A3, 300b, 845 in SE, PSE and PP.
- When all things are equal 845SET is the King of SET.
- 845 will do everything 300b does and more.
- 45 and 2A3 are slightly better in the mid and high but much lacking in low.
- 845SET is sound stage champ.
- My other speakers are Melior One (87db). 845 will drive them.
- Output transformer is the most critical item in SET.
- MHO from MOE. So, don't shoot me.
- I have few more amps and motorcycles. Because, I'm only allowed have one wife.

Best regards...
Twl - Interesting posts. I know a guy who is doing something that should get the attention of all of us. He has a 24 wpc 845 SET amp on a pair of Spendor S3/5's. His listening room is small, and he doesn't want to disturb the neighbors. It's a crazy and simple setup, but it sounds amazing. Another interesting thing he done was to eliminate power bars and line filters. Since the amp is integrated and he only has one source, all he done was bought a Hubbell duplex outlet and installed it, and plugged both components right into the wall.
I thought this was a nice 845 page; all 4 chassis and 282 lbs of it: http://www.cognitivevent.com/av_monstro.html.
Octuple, I went a step further and had custom made gear to run on 12vdc power, with separate batteries for each piece.
It's amazing to hear what flat DC battery power can do.

Simplify and enjoy.
Amen to DC power. One amp I'm having very hard time getting rid of is N.E.W. DCA66 which is battery powered class A SS amp. Disabled half of the power per Cary's recommendation and it is SWEET. It is a Nelson Pass designed and Cary built amp. I'm a die hard SET guy and this is the only SS amp I enjoy time to time. Amen to "simplify and enjoy" too. I don't use preamp nor x-over speakers. I use digital volume control by Meridian in front of the DAC to SET to x-over less speakers all connected with siler cables. As pure as I am able to get.
I took ownership of a Bel Canto SET40 a little less than a week ago, and got in a lot of good listening time this weekend.

With the exception of this new amp, I am running the exact system listed in my virtual system, which consists of a solid state BAT VK200 powering ProAc Response 2.5s.

My impressions agree strongly with Dopogue's experience. The ProAcs sound fantastic driven by the SET40. The thing I am most surprised with is that the 37wpc SET40 nearly matches the dynamics, drive and bass weight of the VK200. All this with the sonic positives the SET brings with it.

A very pleasantly elated.
Gunbei, welcome to the King of SET Club. SET40 is a very special amp. First, while other 845 SET produces 25wpc, it produces 37wpc. Second, while other tube amps have dynamic peak power of 150% of rated power (at the most), its got 70+wpc of dynamic peak power (200% of rated power). By commonly accepted rule, it is equal to 200+ ss watts. I don't know what tubes came with it but if they are stock tubes from Bel Canto, you haven't heard the SET40 yet. More elation to come.
I just bought the Cary CAD 211 Anniversary amps. I am hoping they will be great, I have not received them yet, but they have a helluva tube compliment. 4 x 845, 4 x 300b, 2 x el34, 2 x 6sl7, and 2 x cats eye. 70 watts class A, 110 AB. Anybody ever hear these, or compare with any others? I have been told they are suppose to be world class. I bought these over the Dehavillands, and VAC phi's, and Tube Research GT-200's. Did I do it right?
845C, anyone hear these, or deal with this seller?

I just bought the new Aries g I have the S A P Quartettes. I also have the 845m,tubes. I need sun glasses--compared to the stock 845s--I stuck my speaker grills in front of the amps to diffuse the intense light. While I don't have more than say 150 hrs. on them I am disappointed,so far.These have none of the mid-magic I got from my Sophia Princess 845---but they are much more dynamic. (Audiomecca/ Placett passive and AU 24 wires)
The 845M tubes are bright (light-wise)! I understand from the Supertnt.com web site that they are no longer available. There is a lengthy explanation about this; from the clunky Chinese-to-English translation I gather they are redesigning them.
Which 845 tubes, do you guys recommend?
Thanks for the welcome Zt000. I'm definitely open to more elation, heheh.

The tubes that I have in there right now are a pair of standard 845s I purchased from Upscale Audio. I plan on looking into the 845B as well.

In the past, I've spent a lot of cash on NOS 6SN7s and 6922s for my other components, but was hoping to stay away from the NOS 845s because of their even higher cost. However, one thing that makes me feel better about this tube is the long life expectancy I've been reading about.

What are some of the 845 variants I should look into, and what are their corresponding prices? What are their sonic charactersitics?

Gunbei, first, I'd recommend that you get the best 12ax7 you can get. Mullard, Telefunken or Amperex are good place to start. I'd recommend paying extra for premium-matched quad. They sound better and last longer. 845s are kind of sensitive to input tubes. Once you settle with input tubes you can play with 845s. I recommend Billington Gold as a very good starting point. Both 12ax7 and 845 will last 8000 to 10,000 hours. Once, you settle on tubes, you can forget about them for many years.

1. There is the standard 845 tubes
2. There is the 845B tubes which are supposed to sound better than the standard 845 tubes
3. There is the 845M or metal plate. It seems the production of these may have stopped till modifications are made. Be careful when using these tubes as the current requirements are different and some amps may not be able to handle without modifications. In the Dehavs they have to be biased a whole division lower on the scale.

4. 845 NOS Tubes. They cost a fortune and sound a bit better than the chinese 845s.
Abrahvt, thanks, do you recommend 1 over the other personnaly?
What is an 845C? Anybody know?
As you go from the standard 845 to the 845B to the 845M the sound gets smoother with more detail and texture in the midrange. The presentation gets darker and more relaxed. It is a matter of preference. I would recommend atleast the 845B. I think the 845C is the same as the metal plate. I could be wrong.
That website shows this tube available, but not the 845M, thats why I am asking. My amps will be delivered by the end of the week, and I am a tube junky, so I wanna get set for some fun rolling. Too bad they do not have M's to ship now.

Can anyone answer this question? My Bel Canto SEi40 was working perfectly with stock Chinese 845 tubes (Edicron), but, of course, I tried new tubes - 845Ms - suddenly, the amp programming/control mode went beserk - muted intermittently, and switched itself on spontaneously without touching the standby button - only with the 845Ms!!! Can there possibly be any relationship between the IR sensor of the amp and the 845M tubes????

Then, when original stock tubes were put in, no more erratic "possessed" behavior by the amp!

Any input, other than "don't be insane" - would be appreciated!
The plate dissipation of 845M metal plate is lower than the graphite plate 845. I would contact BelCanto to make sure that the amp plate dissipation is within the range for the Grid Bias Circuit.
Who has a quad of 845B/or M to sell NOW please.

711Smilin,You can buy my matched pair, since they sound great but screw up my Bel Canto IR sensor...............must be a mismatch between Bel canto and 845M of some sort.
I agree with other contributors, what a good thread. I am ashamed to say, I had heard little of 845's until the recent UK Hi End show at heathrow. Nick the importer of Viva amps was using the Solista integrated to drive sensitive ART speakers in a very large room to very good effect indeed. That's just 17 watts and more than enough. i have always equated SET amps with 3 to 8 watt 300B amps and have not been that impressed I am afraid. Not bad, but certainly not the drive of the Solista. Well I have just aquired a Solista on the Audiogon site, it is an evil looking brute, but managed to persuade the wife it had a sort of industrial chique. Who can resist the thought of Italian design. I am looking forward to its arrival, yet another bargain for a UK buyer. Not that I'm gloating, but the price of the dollar makes direct imports very tempting.
Those 845s sure are bright, aren't they?

I've just gone eight years of SETs and 20 years of tube amps in general to a Plinius SA50 Mk III. Good luck to me!