845 Tube vs KT90

Why not a 211 or better a Cary 805 AE with switchable 845/211?

You're not gonna let off the hook for that, eh?

Any SE output transformer, including PSE, should require an air gap and larger size for the same output power as PP. SE also requires greater power supply attention because it does not benefit from the same noise cancellation as PP. I think these two things increase overall cost compared to a PP amp of the same power.

Soundwise, I can't speak from personal experience, but many posts on AA's Tube DIY forum mention a loss of clarity or focus with PSE relative to SE.

Of course, like all things in audio, those opinions may have more to do with poor implementations of the topology than actual flaws of it.

YOU mentioned that they "come with drawbacks" What are the drawbacks you're talking about?

Hi Warrenh,

I was mistaken in my description, the SET-80 isn't SE, parallel Single-Ended (PSE), bridged, push-pull, or parallel push-pull(PPP). It's a kind of a hybrid of all.

What the advantages are of that, I have no idea. Total harmonic distortion is specified at 0.05% at 1W, 3% at 70W clip.

To quote the Stereophile review from 1998:

The close relationship between Bel Canto's SET 40 stereo amplifier and the SET 80 monoblock is evident in components and parts—and the virtually identical chassis. Ingenious use of a high-quality, studio-grade input-matching transformer transforms the stereo chassis into a monoblock with the additional versatility of balanced and unbalanced inputs. This is a function of the center-tapped, balanced winding of the input transformer, while its secondaries allow phase inversion of one amplifier channel relative to the other.

At the loudspeaker outputs of what was the stereo chassis, we now have a balanced signal that—if appropriately connected and ratio-matched via the secondary windings of the output transformers—provides doubled output power in monoblock mode. Conceptually, the result is an oddball—it doesn't fall neatly into the usual class-A, SE, push-pull, or bridge categories, as it contains elements of all of them. (diagram)

Finally, in fig.3, the SET 80 monoblock version of the SET 40 stereo unit is shown. While the output transformers remain separate, the loudspeaker connection is made via a loop containing both secondary windings arranged as a bridge connection. As in the push-pull design, the tubes operate in antiphase, but no phase splitter is required. This task is accomplished by Bel Canto's addition of the balanced/unbalanced input transformer. The amplifier does have a differential topology that will help reject noise on the high-voltage line. This is run in class-A so that each output transformer is magnetically biased; this is said to improve the incremental linearity of the magnetic material. The cross-connected output infers bridge mode, yet the floating transformer secondaries allow the output to be ground-based, avoiding connection difficulties with subwoofers and headphone adapters.

Those four triodes at the input (two 12AX7s) are connected as a differential pair. SRPP mode is achieved by the second pair, the stage said to deliver a low-distortion signal up to 100V rms from a low 1k ohm output impedance, which will fully drive the 400k ohm input grid resistor of the output triode.

*** Still, I'd got for a really good PP amp over a high powered if not using speakers over 94-97dB, maybe even 100dB.

I believe they still sell the mono blocks, as well, but the price is signifcantly higher. More like $19k a pair! Darkmodebius, what are some of the drawbacks of doubled output power? I'm not going there, but interested never the less.
warren :)

Bel Canto also makes(or used to) and SET-80 monoblocks which use two 845 in parallel push-pull for 70-80 wpc. I think it sells for $8k a pair new.

The only problem is that there is no free lunch in audio design and the doubled output power comes with some other drawbacks. As to whether they matter or are audible is a debate for those with more technical experience than I.

There is a Bel Canto SET40 amp for sale with KR845 tubes on the 'gon for a ridiculously great price. It's the same amp I have, less the KR 845s. $2500!! They still, (although it is not on their web site) make this amp. Sells brand spanking new for $5500. And it weighs in at 85lbs. You got a thing with componenet weight? You mention it often. Heavier the better? lol...

I've owned both JA-30's and JA-80's (numerous NOS KT-88's, EL-34's and KT-90's) when I had Crosby Modified Quads and they were great sounding amps. Yes the music and picking speaking to fit that music are the two most important things to do. I switched in the nineties to Wilson's and two Audio Note Ankoru's (PSE, two 845's for output and a 300B for voltage driver for each mono amp). Miss the quads at certain moments, but the Wilson's with 845's fit my taste much better all around than anything I could do with the JA-80 with any KT-88 or KT-90 tube type. The 845's are my choice for amps now. Perhaps looking at Wytech's products might produce music magic at a sensible price. Speakers must be >91dB sensitivity or better. Take a look at Coincident Speaker Tech for a speaker you might like with your tube choices.

http://www.coincidentspeaker.com/

Aren, Dark, thanks for helpful imput.
Both of you raise my awareness of what the 845 SET (most are low powered, thus higher sensitivity speakers are best option) are alla about. Aren you mention the Ming Da, is that the ones that weigh in at 375 lbs!!! I saw a pair for sale here last month, a sweet deal at $3500. But alas too heavy for my back to move around. Besides they are rather large and not all that attractive. They were 80 watt push/pull. I also heard a big Audio research + ARC pre on Magnapans at a dealer in New Orleans months ago, they sucked the amp dry with no dynamics on orch. I hearda Conrad Johnson on Martin logans once and sucked dry with orch. The cayin 300/Silverline Sonata combo could not bring any life to orch. For light jazz/vocal the 300/Silverline was UNREAL, liquid and sur-realistic.

I do not know all the specs on the Thor/Seas, just know they are not the ideal speaker for tubes. Jadis' famous high power trans deliver the power for orch presentation from the Thors.
I'll share alittle story(yet again) on the ability of the JOR's power for its size. I first got it in and a friend asked to bring it over and hear it on his Mirage 1's, beast ofa spaeker for tubes, close to the level of demand as the Vandy 3's. We unhooked his massive Audio Research VT200 and ARC pre and to his surprised delivered some slam , but even better details than his ARC setup. But obviously the JOR would blow with continued use.
Anyway based on the above comments, I may just stick to what I know I like best, which the KT90 does overall. Budget? yea that is up in a ?. If the yr goes as i hope, a used JA80/KT90's may be my best option for the music i listen to. as in all things audio, compromise. Dark may a good point " really well implimented push/pull is just as good as SET's maybe even better"
Appreciate all the imput, sets my course straight.

Bartokfan,

I think you are trying to use the wrong tool for the wrong job in your amp search. The vast majority of 88dB speakers are not intended to be used with SET amps. It's no wonder 300B amps sounded flat.

To build on Audiofeil's analogy, that's like bring a Yugo to a tractor pull.

Before asking for suggestions you really should find out(or tell us) the impedence curve of your MTM Thors. 88dB by itself is not that difficult to drive, but are they 4 or 8 ohms? Do they dip to 2 ohms at some frequencies? It's going to be the dips that cause all the problems.

Also, what is your price range?

Personally, I don't think SET amps can truly handle dynamic peaks of large orchestral at medium-high volumes unless you are using 100dB+ speakers. I've got 95-97dB speakers and that is a stretch.

If you really have your heart set on 845 SETs, then I'd look at the manufacturers that are famous for high-current/high-output SETs - Dehavilland 845G-SE, Art Audio Concerto($12k), KR Audio (non-845, but high powered).

Be prepared, good high-powered SETs will cost a lot. The output transformers and power supply necessary to handle that kind of current cost a lot of money.

Remember that dynamic peaks with well recorded vinyl can be 14-20dB higher than the average listening level. So, if you normally listen at 85dB, you will need 32wpc without clipping to handle 106dB peaks effortlessly. Which will likely be a 50-60wpc, at the least, to stay in it's lowest distortion range. Good classical cd recordings can bee even more demanding.

My personal opinion is that in the high-powered category, really well implemented push-pull is just as good SET, maybe even better. It's definitely cheaper to with PP to get an equal level of performance. And you'll have a lot more choices.

Why not check out ASL Hurricanes (200Wpc, KT-88), Art Audio Concerto or Opus Ten(KT-90 or 88), Cary SLA-80(KT-88).

I can't comment on the KT90 tubes, but I do have some experience with 845 tubes in different set-ups, and I think it could be of help.
A while ago I borrowed a well-designed and well-built pair of 845 SET monoblocks from a befriended dealer. It had 300B's with anode choke as driver, and a 6SN7 first stage. On his own speakers they performed well. On my ESL57's they gave a very flat soundstage, same as you describe. Even the general direction of the instruments was very vague. The instrumental timbres were not natural; everything sounded alike.
Earlier I had borrowed a 300B SET (again with 6SN7 as first stage), and that gave the same results.
But: I have also listened to 845 push-pull monoblocks (Mingda MC300845-AB) on my speakers for a few hours. Apart from being a push-pull amp, the tube line-up was very much the same as the 845 SET's: Anode choked 300B as drivers, first stage with 6SN7, and no global feedback. The result was fantastic, with good depth and placement, and a very good rendering of the instrumental timbre. The most lively and involving sound quality I have experienced so far, while the other amps with exactly the same tubes were the biggest disappointments I ever had.
The only reason I didn' buy them is that I can't stand the sight, especially with their protection cages. Every now and then I still think of buying them and have something different made.

Same as other people have commented: It's not just the type of tube that means success or failure. I do have some idea what it is that makes the difference with my speakers. ESL57's are a reactive load, so the amps needs to be able to deliver a good peak current. That makes SET's not very good candidates, because they are low-powered amplifiers with a relatively high output impedance. The push-pull 845 amp had 70 Watts, so could still deliver enough peak current despite its high output impedance. My own Fisher SA16 (EL84 push-pull) has low power but with a very low output impedance, which also makes it work well. Until it runs out of steam in really big orchestra pieces, that is...
I can't really explain how this translates into things like soundstage, so it's not a proven fact but an idea that seems to make sense. And, I am not familiar with your speakers so perhaps your experiences will be different if you would try an 845 PP amp. Don't jump to conclusions just because I had a good experience with these.

The best thing is to listen to as many different types of amps as you can on your own speakers. I hope you have a few friendly dealers near you. Learn what works well or not: SET's, push pull, OTL, high or low power, whatever. And trying to get an idea what makes the difference can help you find your way through the wilderness.
I take my speakers to the dealer if he won't give anything on trial, which is not very practical with ESL's but well worth it in the end.

Warren I received a PM from a member who also said he loved the 845 magic, just wrote a second Pm and said this of the 845 on orch: "positions each section of the orch , can hear individual instrument solos"..."floating harmonics in space" IOW not restricted/confined. He also mentioned he does not like a bloated thick/heavy midrange again we are giving our opinions so whats great sounding to one, may not be too another. My friend here in BR, a Agon member , has the Vandersteens 3's. He loves what they do, to me they are too thick, I feel fatigue. I guess he feels my Thors are too 'thin/sharp/cold", which to me is my ideal speaker.
transfer this to amps, the 845 may suit some perfectly, and I've yet to find out. Of course we have 845 amps all the way from the Ebay chinese offerinfs at $800 intergrated to the big $12K Cayin mono blocks, also the famous and rare Jadis 845 monos.
In the PM J also mentioned that "orch is the acid test of any amp/system". I agree.
In my current system, the JOR (Jadis's smallest offering) is not bringing out all the potential the Thors hold. And if I get the Tyler W2's in the future I need something that will A) meet the demands of the Seas drivers/bring out the potential B) deliver orch with the separation of each section, fine lines/sharp/details. Which is the character of the KT90. I'm willing to give up some of these qualities to the 845 in exchange for "floating harmincs" "the 845 magic".
I'm not far from Houston, maybe there are audio dealers there with the 845 amp.

Bartok, is it ever reliable to convey via language what a tube, component, etc. brings to music? Still, wouldn't you, regardless of what beautiful descriptive language you read describing a tube etc., want to listen yourself? The CES show is your answer. A tough place, sometimes, to hear what is true. I have a good feeling that the 845 tube will deliver your goods. It does for me, at least. good luck and let us know what you discover. warren

Tvad the CES would be an excellent opportunity for hearing the 845 , there should be at least several offerings on this amp at the show. But alas, one more yr not financially able.

I do not listen with the JOR's tone controls all the way up, only at 80% open. Basically the tone controls have 2 settings, ON/OFF , as they have very little sensitivity to change on the dial.
You'd have to chat with the local tech guy here in BR for him to explain it to you. He placed the tone 75% open and said thats where he'd listen.
What i'm after is a bigger amp, with more power. But i do not want to lose what the KT90 offers, which is one of the nice reproduction for classical music, to my ears.
Most of the fq's in orchestral instruments, winds/brass, strings are mid heavy, so the 845 may bring out these fq's in a way i like. But like someone mentioned above every 300 tube amp will have some differences. And so every 845 will have lend own character to the tube.. I guess its not so simple to convey what a 845 tube brings to orch music. It has to be experienced in an audition.
seems the CES show is the one place where alot of questions can be answered in hearing the different set ups, set/push pull, high sensitive speakers etc.
Thinking it over the Seas speakers (Thor, Tylers) are not going to be the ideal match for the 845. Its just my intuition. I may have to go with this combo Melody's big pre amp, the one that weighs in at 50 lbs!! and a used Jadis JA 80 monos with KT90's.
And be done with it.
I'm sticking with this game plan.

Funny you should ask. I posted the answer to that question on the 'gon just today. You'll find it. It's "Nirvana at last?" And yes, I can keep my thermostat down a degree or two when listening to my rig..lol..

Ahh, Warren, you're making it even tougher for me to hold out!! Heheh. How does your BC combo make your Zu 1.5s sound?

Another thing is that I really miss how the SET40 warmed up my room on those cold days!

Gunbei, I'm presently running with a Bel Canto SET40 matched with the Bel Canto SEP1 preamp. They work beautifully together. Classical music sounds beautiful to my ears...

"why not take a trip to Las Vegas this week to hear some of these options for yourself?"

Because CES and AVN are no longer concurrent held! Rats!

I don't have a direct KT90/845 comparison to offer, but I will say that after using only solid state amps in my apartment I was very pleasantly surprised at the control and impact the Bel Canto SET40 had on my system.

The SET40 is an 845 amp rated at 37wpc, and aside from the nice tube sonic characteristics it didn't give up much slam compared to a BAT VK200. This was something I definitely didn't expect. I often switched back and forth between these two amps which were running a pair of ProAc Response 2.5s. Most ProAcs have a sensitivity rating of around 86-88dB, but I believe they have a pretty mild impedance curve which allows them to mate well with amps that would seemingly be underpowered.

When the finances allow for it, I'd definitely like to get a hold of one of these amps again.

Boa2, wouldn't that comment have been better communicated through an aside email? Punitive, public tongue lashing, with your normal pedantic, oratory is hard as usual to take. I would have sent you this email on the side, but I know that I am banned forever from sending you emails. I honor that, but not your self-righteous, full of yourself, 'tude....peace, warren :)

i guess I want a tube amp to deliver the lows and highs with minimium roll off. And no muddy/murky/smokey mid section.

Based upon your comments here, and in previous threads, I would suggest listening to some push/pull designs.

>>unless the tone controls are biased up almost all the way.<<

That's hilarious.

Audiofeil, please tell us you have something better to do than follow Bartokfan around these threads. Almost daily, we read about the demise of this hobby, due primarily to the abrasive attitudes of dealers like yourself. What is the purpose of berating people here? Your closet is not free of skeletons, and yet no one is constantly targeting you, as you are others. Your previous behavior in these threads was totally unethical, and yet you returned to the discussions without humility. You have 40+ years experience in this hobby. Why use it as a weapon, when you could just as easily encourage more people to participate in high end audio by educating them with a sliver of empathy for what they don't know. Please consider it.

lol


:)

>>unless the tone controls are biased up almost all the way.<<

That's hilarious.

How do you expect to evaluate any amplifier, speaker, and/or tube combination with tone controls maxed out?

Lastly, it is disingenuous to judge the qualities of any output tube heard only in Cayin equipment. That is anlagous to judging all gasoline powered automobiles after test driving a Yugo.

Jeff interesting post. The 845 I am interested in are the Cayin mono blocks, not the big ones, its the $5K model. Not sure of the specs, it may be push pull. . IOW like the Cayin 300, they offer 2 models, the push pull (P) and the 300 set (D model)
I believe I heard the push pull with Silverline Sonatas, 4 yrs ago. I guess the push pull 300 will have more drive for orch vs the set model. So my opinion can't be established until I know which model I heard.
I'd love to audition a 845 in my home.
So there is a ;pw powered SET 845 and the push pull 845.
btw the JOR is rated conservative 40 watts, but tends to be flat unless the tone controls are biased up almost all the way. Which I've been told by the local tech guy is not a proper image. But hey i like it that way and thats all that matters.
I'm interested to know if the 845 will present the orch without the need for pumping the bias up. IOW w/o the use of the tone controls on the JOR the image is way too flat.
The Chinese KT88 amp I demoed at home was useless on the Thor'in any music.
It sounded like the old 60's AM radio.

When I play Faith Hill and the bass tone turned up, vol at 9 o clock, the 7 inch midbass flutter being so over loaded. So the JOR has power, but only if boosted by the tones. i guess I want a tube amp to deliver the lows and highs with minimium roll off. And no muddy/murky/smokey mid section.
Is there such a beast?

Bartok, I think your experience with other output tubes is experience with those AMPLIFIERS. An excellent-sounding amp can be built around vurtually ANY output tube. Also, 845-based SETs, which usually have 20 - 25 Watts, may well be short on power for ANY speaker with sensitivity below more than 90dB.

You don't tell us how much power your Jadis amps have; how much?

One alternative to 845-based SETs is the Antique Sound Lag Cadenza, a push-pull amp of 60 Watts... http://www.divertech.com/aslcadenzadt.htm . Harry Pearson raved about them in his review of the Hansen speakers in the January issue of 'The Absolute Sound'. Rather expensive at $6K.

I use ASL's new 845-based SETs, the AQ1006(845)... http://www.divertech.com/asl1006845dt.html ...to drive my DIY 97dB-sensitive line-array, open-baffle speakers.
[IMG]http://i89.photobucket.com/albums/k220/jeffreybehr/OB%20JG6518%20speakers/12Decfmlisteningpos_800w.jpg[/IMG]

They sound VERY good together on aLL the music I play, which is mostly large-scale Classical and film music.
.

Still looking for a solid opinion on the general character of the 845 vs the KT90 on classical.
As I say i'm very happy with the JOR but having read all the comments on the magic of the 845 I'd like to know if this would bring another dimension to classical.
If the 845 is brother to the 300B then it aon't gonna happen. Classical, orchestral I'm refering to, totally overwhelms the cababilities of the 300 tube. Even most KT88 amps I've heard have difficulities with orchestral. Have not heard the EL34's. The KT90 may be the ideal tube for orchestra.
Thoughts?

I dont know what amp you heard the 300B's with but they can be stunning in a push pull set upX4. The mids are somewhat colored and the bass is uncontrolled but the highs are very nice indeed, Too bad i ran them into clipping too much so I sold them . Ca 339

I'm a jazzman, but do Mozart, Vivaldi and their friends quite often. I'm driving 101db speakers with 40 SET wpc. My speakers never drop below 6 ohms. I get all I need from the Brandenburg Concertos to Stravinsky's (some serious SPL) Firebird. I cannot imagine stella satisfaction with an 845 tube with 88db speakers. I would always be yearning for more when playing big symphony music. I would think in terms of more sensitive speakers, then hook up with an SET tube 845 amp/pre. It works for me.
warren

I just googled here "845" and see the old topic "Tube fever, 845 set amps"
I read where EJLIU posted on 1-14-06 "most 845 SET 40 watt amps do not do well on low impedance speakers". So like the 300B tube, the speaker must work around the 845amp.
In my game speakers come first, the tube amp has to work for the speaker.
Besides the Cayin monos have a single 300B tube with the driver 845 tube on each chassis, that alone should raise a red flag, in that the speaker must have good sensitivity for the 845.

Yeah good point. Does 845 fall into the category of the 300B tube amps?
Meaning higher sensitivty speakers suits the 845 better than say a lower sensitivity?
I have the Thor a MTM with SEas drivers. Like 88db, the JOR does OK, but would like something more in my music, presence. Don't we all?
Anyway I have intentions of getting the Tyler Woodmere 2's...one day.... So that may be part of the equation. I think they are like the Thor's 88db..?? I do not want roll offs in the low and high fq's as was my experience of both the KT88 and 300B tube amps.
Q: should I stick with what i already know I like? The KT90 sound. But maybe upgrade to a larger KT90 amp? Which would be the Jadis DA60 (or mono blocks with 90's, as I'm looking at a nice preamp i really want).
.