Tube amplifier suggestion for 101 dB speakers

Linear tube audio

https://www.lineartubeaudio.com/products/zotl-40-reference-amplifier

As built by VTA, the M-125's were very noisy, but can be quietened quite a bit. In my case, almost 40db.

Not sure that would be enough for 101db speakers. I'd look at balanced solid state. VERY Low noise = $$$

Complete instructions:
http://ielogical.com/Audio/VTA_M-125.php

I’m not looking for an integrated amplifier, never liked them, need the flexibility of a preamp.
These Line Magnetics are very rare in this NA market at this point, at least what I can see. They may be good though.
 Thanks.

Dear Op

If you are serious, then go for Line Magnetic 508 even if it means stretching your budget.

https://reverb.com/item/17478397-line-magnetic-508ia-single-ended-triode-vacuum-tube-2018-black-clas...

I am driving my 99db/W speaker (Lansche 4.1) with Silbatone 8W 300B SET and Line Magnetic 508 48W SET to get the most out of it.

http://stereotimes.com/speak112410.shtml

With Line Magnetic 508, I have more headroom than Silbatone although Silbatone is more transparent using exquisite silver foil output transformer.


After you buy it, if you replace SN7 with Sylvania 1944 Nos Vt231(around 150$ per pair in Ebay) and SL7 wih Mullard EC35(around 125$ for single tube), then it sounds excellent.

Later you can also replace 300B and 805 with new production Chinese tubes called Acme series or Shuguang Treasure .

I kind of understand now these particular types of tube amps and how should they be matched.
And more and more I think that the problematic thing here is the 4 Ω / 101 dB combination for the speakers I have.
So there is no need for high power, that's a SET amp then, class A and no need for biasing anything. Cool, but I need a stereo, preferably with XLR in. I can hardly find something used under 3K.
I thought a BAT VK-55 would be good, but that,s not a SET.
I'm telling this territory is not easy, a push-pull would be much easier to pick.

piramis OP
 The speakers are highly efficient here with 101 dB, but also they are 4 Ω in impedance

Yes as I said before, and that’s a nominal 4ohm, it will have dips even lower than that.
Look for an amp that has a 2ohm speaker tap just in case beside 8 and 4ohm.

The 100w per channel Music Reference RM200 has a 2ohms tap which should still give enough watts from that 2ohm tap for your 101db speakers in case you need to use it.

http://www.ramlabs-musicreference.com/music_reference_rm-200_hybrid_power_tube_amplifer.html

Cheers George

You're on a good track. Even with SET amps, there are a number of different tube types which each have their own relative strengths. For example's sake (please don't flame my oversimplification here):
845 - a bit more powerful, good dynamics & bass slam for a SET type
300Bs - beloved midrange, magical vocals, acoustic guitars, cello, etc.
2A3 - great imaging, traditional warm tubey colorations
45 - lowest output, need highest efficiency speakers

Try researching articles like this to learn more on the differences:
https://hometheaterreview.com/whats-so-irresistible-about-a-single-ended-triode-set-amp/  Sorta simple, but it's a start. Cheers,
Spencer

That's right, I'm not driven here by need of high power.
The speakers are highly efficient here with 101 dB, but also they are 4 Ω in impedance which I guess will limit the amp selection.
Here is the Atma-Sphere S-30 but they want 8 Ω and up speakers at least. This is an OTL type amp.
Then come the SET amps, I think this is the category what I need.

You might also consider this:

http://www.decware.com/newsite/SE34I.htm

My experience is that you sure don’t need - and probably really don’t want - 75 watts for each of those really efficient speakers; because amps just sound better when they are using more than just a tiny fraction of their power.  I mean, I’m not an electrical engineer or anything like that - somebody more knowledgeable than I could explain it - but I believe this is why a lot of receivers and amps had loudness switches or dials.  Turn the main volume up and flip or adjust the loudness when playing at low volume.  

This point may of course be secondary to your decision.  But you really don’t need 75 watts per channel for really good sound.  I think using the amp in the link above or another of the few competing American made little SET amps is the way to get really nice sound out of super efficient speakers like yours.  

So, maybe you’re wondering if they will play loud enough without distorting.  Don’t be mistaken... you can still get your speakers loud enough to have the neighbors call the cops... with the volume knob less than half way up.  

How about Atma-Sphere S30, SETs from Dehavilland like Aries 845s, even the inexpensive Jolida SETs if you can find one.
Perhaps someone can chime in regarding experience with 300Bs when dealing with a 4ohm load? That would help him narrow things down a bit. Cheers,
Spencer

Actually yes, looking at the specs of my speakers, the logic says to go with SET amplifier.
The  Atma Sphere S-30 looks interesting, but is classified as an OTL type.
Now what?

Thanks for the input.
Actually I'm learning as I'm reading about these different tubed designs, never had one before. And there is a lot to read and learn actually.
And am having a look at all these proposed units.

With 101db speaker, you'd be doing yourself a disservice if you buy a higher powered traditional push pull pentode amp without first trying out a SET, OTL or other design that prioritizes great sound over high power output. If the impedance doesn't allow for such, that's a different story. 
Posts above are a combo of good suggestions (e.g. Viva  or Dennis Had's SET amps) and some that seem like they are coming from those with lower efficiency dynamic speakers and are just telling you to buy what they know/like with those designs that have totally different needs than you do.
I have a ton of respect for Rogue , Music Reference and Quicksilver but for your situation it sounds like doing surgery with a machete instead of a scalpel. 
How about Atma-Sphere S30, SETs from Dehavilland like Aries 845s, even the inexpensive Jolida SETs if you can find one.
Perhaps someone can chime in regarding experience with 300Bs when dealing with a 4ohm load? That would help him narrow things down a bit. Cheers,
Spencer

I propose: Unison research unico 100, Copland CTA 501 tube power,Phatos Logos,Jadis DA 50 s en -DA 30. You will hear the difference . Jadis and Copland the best for their price. Look at 2hands

shkong78 wrote:

The used ST-100 could be best starting point for you.

If you change stock 12AX7 to Telefuken( around 200$ per pair) and 12Au7 to Amperex NOS (around 120$ per pair), it sound very nice.
Tungsol KT 120 is good and not much choice for tube rolling.
It is not that difficult to adjust bias manually.
Once you do it, it keeps the value for several months or more.

The Rogue ST-100 definitely looks interesting to me as I said before.
Since I want to get involved manual bias won't be a problem, actually would prefer that.
By the way, did these amps have different generations thru the years? Probably not, but the only thing I see that the user manual from their website was issued in summer 2013.

remember, 80% of the sound is made in the first 20wpc.

if you are not yet a brand snob, the BC Crimson stereo amp is a real over achiever and will supply enough power I suspect for your transducers.

I have no dog in this hunt what so ever but have heard the crimson recently and thought it an exceptional amp at well above its price point .

so I’ll also say ‘plus one for the Carver crimson 75wpc stereo tube amp’.

at well under $3K, with as was said, a 30 day trial… tell me, exactly what can you possibly lose by giving one an audition in your own room?

it beats buying on speculation AND adds to your Experience.

 

it is a manual bias amp.

has 4 & 8 ohm taps.

RE Auto vs manual bias

this is pretty much a pick ‘em debate. it lays in the who’s making the auto bias amp IMO.

on the other hand, a manual bias amp enables the ‘tweeker’ in us the opportunity to check and recheck bias every 12 minutes or so. loll

usually manual biased amps as has been said, hold bias well. that ins once they’re run in some. 

AS Ralph said, once you hear the effect tubes have with detail and so forth, you will either dig them/it or not. if you do like the presentation, obtaining a preamp that as well is glass topology will enhance and ordinarily  escalate the overall performance level and bring more ‘life’ or ‘reality’ into the room.

tube amps generally capture more reality given the same dolar amount as SS amps. 

in other words, it takes an  lot more money in SS to do what tubes do for very often much less.  

again, IMHO.

as for which tubes are still out there? well there is a finite supply. especially in New Old Stock (NOS) tubes. 

don’t let that stop you or scare ya. therre are still enough solid choices and availability to enjoy some occasional tube swapping or ‘rolling’.

Google is your friend so use it. I think there is a pretty good primer on the sound of this or that tube called “Joes’ tube lore’… I think. he is mighty close on what many of those tubes provide sQ wise. 

once you’ve settled on tube amps, if that is your choice, there are tons of folks here who have a wealth of EXP with various tube brands, and types. 

just ask.

it may seem daunting but really its not. 

good luck!!

+1 on Gold Lion KT77 tubes.....they are awesome
Larry

From what I have read . The Primaluna does not drive the tubes as hard as the Rogue , needs more tubes to get the higher watts . Primaluna states there tubes last longer than most amps .

I would buy one of Dennis Had's single ended amp either new or used. Well under your price point and they do sound really good. Much better than any SS amp I have heard.

Yes I'd like to keep the Classé Sigma pre because it has all the features I need in a preamp. But presently having no experience with tubes, I do not know which mix [tube pre + ss amp] or [ss preamp + tube amp] has more effect on driving my speakers or generally.

If you get a tube amplifier and you find that what everyone has been saying about them (smoother, greater detail) is true, then you will want tubes in the preamp too. You get the same benefit.

Bob Carver Crimson 275. 

Satisfaction guaranty. No re-stocking fee if you don't love it!  Jim Clark Stereo. Free shipping to you.
 Endless system combinations, room effects and personal taste make decisions difficult.

JCS made this offer since the Crimson 275 was introduced, and lets customers compare with their exiting amplifier. No restocking fee to cost you money. May the best amp win, in your system, in your home.

Sold them as far away as Israel and Switzerland.

Customers keep them..

Yes, Primaluna HP has lots of video, demo, etc on the internet.
What I notice as a dilettante is that it uses 8 x EL34 and 6 x 12AU7 tubes from factory. Why is the high quantity of tubes, 14 compared to 4 + 4 in the Rogue ST-100, the latter being even more powerful with the same KT120s.

Not sure why all the tubes (4 amp tubes per channel)...I do know that’s its integrated (so no pre amp needed) built incredibly well (point to point wiring, etc.) and has a very good headphone output included. If I recall the way its built makes it not work as hard extending life of components.. It has a sub out too.

It is also a class A amp/pre amp and the mojo is tops. Output power isn’t the be all and end all...I think the more knowledgeable hifi gurus factor in bandwidth too. You can run KT120s or KT150s in the PL.

Putting on my dilettante’s extra large hat I think its as good or better than some top mono block systems I have heard. Yes it’s subjective but I’m not the only one thrilled with it. For the money nothing comes close. Oh course money and hifi upgraders are the preverbal rabbit hole. I have upgraded from Revel speakers but will stay with this integrated amp.

You may also find that a power conditioner and some good heavy cords will help your speakers too. See the rabbit yet?

https://www.audiogon.com/listings/lis9cag6-rogue-audio-st-100-tube

The  used ST-100 could be best starting point for you.

If you change stock 12AX7 to Telefuken( around 200$ per pair) and 12Au7 to Amperex NOS (around 120$ per pair), it sound very nice.

Tungsol KT 120 is good and not much choice for tube rolling.

It is not that difficult to adjust bias manually.

Once you do it, it keeps the value for several months or more.

First post here but not my first Hifi rodeo. Check out the primaluna HP. It will come with EL34s. Roll those out and roll in KT88 or KT 120’s. I got from Upsacle audio. Ask to speak with Kevin. Before rolling tubes listen to the 34’s.

I’m using the PrimLuna HP/w KT88’s to drive SonusFaber speakers. They need power.

Yes, Primaluna HP has lots of video, demo, etc on the internet.
What I notice as a dilettante is that it uses  8 x EL34 and 6 x 12AU7 tubes from factory. Why is the high quantity of tubes, 14 compared to 4 + 4 in the Rogue ST-100, the latter being even more powerful with the same KT120s.

You mentioned that you'd like to keep the ss pre, however I'm going to recommend that you try a tube preamp for a couple reasons. The preamp tubes can and will tame the treble. Preamp tubes generally live much longer. And lastly, rolling preamp tubes is MUCH more feasible, for example there are basically no nos 6550( a popular power tube) tubes left anywhere, whereas even the most sought after preamp tubes are available.

 Yes I'd like to keep the Classé Sigma pre because it has all the features I need in a preamp. But presently having no experience with tubes, I do not know which mix [tube pre + ss amp] or [ss preamp + tube amp] has more effect on driving my speakers or generally.

All right, I've got interesting and helpful responses, thanks for each and everyone.

You could get a Rogue Stereo 100 100wpc tube amp for around 3 grand. It uses KT120 output tubes and it is a tube rollers dream.

This looks something serious to consider. I do not want to go with mono-blocks, I like the fact that it has balanced inputs and lots of power plus mode switch. The looks it's more of an SS look though. That meter on the top is for bias adjustment reading?
I see that there are auto/manual bias tube amps. In photography using auto mode is for those who don't know anything about photography. Is auto a good thing here with the tubes or manual is the way to go?
I noticed the Primaluna Dialogs are all auto, but the others more or less manual.

I should have mentioned that I have owned that same amplifier and it is really good. Amplifiers like this one are the reason you buy high efficiency speakers...or should

There is an Art Audio 3ooXLS amplifier on audiogon, link below that should make you day.

https://www.audiogon.com/listings/lis9b21a-art-audio-diavolo-13-watts-of-tube-magic-tube

Meant Atma-Sphere

Arms-Sphere for tube amps.

First post here but not my first Hifi rodeo. Check out the primaluna HP. It will come with EL34s. Roll those out and roll in KT88 or KT 120’s. I got from Upsacle audio. Ask to speak with Kevin. Before rolling tubes listen to the 34’s. 

I’m using the PrimLuna HP/w KT88’s to drive SonusFaber speakers. They need power. 

http://www.tubes4hifi.com VTA-120 You can get this 60 watt tube amp completely wired or in a kit, wired for around $1450 to $1650 depending on options. 
I built the M-125 mono blocks over 4 years ago and they still sound great. No frills in the chassis, stainless steel. From the web page - 
The VTA ST-120 is a 60 WATT PER CHANNEL amplifier built on the same ST-70 stainless steel chassis as the amp pictured above.
The VTA ST-120 uses three custom wound USA made transformers and is available as a KIT amp or completely WIRED and tested.
This amp has the same quality components as the VTA ST-70 listed above. The optional tube set has a GZ34/5AR4 rectifier,
three 12AU7 driver tubes and a matched quad of 6550 tubes.
The power transformer instead of 360-0-360 secondaries like the ST-70 has 420-0-420 secondaries and puts about 485 volts on the plates
(pin 3) of the output tubes. The ST-70 puts about 420 volts on the plates. The stack lamination on this transformers is about 2.70 inches tall
- my ST-70's power transformer stack is about 2.05 inches high. This transformer weighs about 4 pounds more than the ST-70 transformer
and is rated at 425 milliamps of current flow.
The output transformers have 4200 ohm primaries, 40% ultralinear screen taps and are 3 7/8" tall, 3 1/4" wide and 3 1/8" deep
(about 1/2" taller, 3/8" wider and 1/4" deeper than a stock A-470 output transformer). Each output transformer weighs about
2 pounds more than a stock A-470 output transformer.
The power storage caps have a higher capacity and voltage rating than the VTA ST-70.
 

You mentioned that you'd like to keep the ss pre, however I'm going to recommend that you try a tube preamp for a couple reasons. The preamp tubes can and will tame the treble. Preamp tubes generally live much longer. And lastly, rolling preamp tubes is MUCH more feasible, for example there are basically no nos 6550( a popular power tube) tubes left anywhere, whereas even the most sought after preamp tubes are available. 

VAC Integrated, old or new.  Even the original Avatars.

Have you thought of a tube preamp or buffer before you give up the Classe amp?

I have a friend who drives his Klipsch Cornwalls using a pair of SET monoblocs with I think somewhere around 12wpc and they sound glorious and can handle loud classical orchestral music passages with ease in a relatively large room. They sound particularly engaging when we listen to more intimate venues and instrumental music like jazz trios and/or music with vocals. He also has a Pass XA30.5 and we both prefer the lower powered SETs even though the Pass has a slightly better bass definition particularly on tougher orchestral content. I would have probably been quite happy with the Pass had I not heard them side by side. 

Even if your speaker has a high efficiency, I do not recommend small power SET amplifier to drive two 15 inch drivers.

I can't imagine why.

My speakers are 98 dB with dual woofers. My preamp has a fair amount of output and in a pinch, I can use it to drive my speakers and it controls the 15" woofer just fine. An SET would do just as well; the big problem is 'will an SET have enough power?' and if a more powerful one that does more than 7 watts then the answer is 'most of the time'.

I prefer a bit more power; much depends on the distortion that the amp makes- if low in overall distortion (in particular the higher ordered harmonics) then it will be relaxed and you will very naturally use the extra power.

I'm thinking of the Quicksilver Sixty Watt Mono's for my ZU Omen defs. The Quicksilvers look nice with the chrome chassis

http://quicksilveraudio.com/products/sixty-watt-mono-amp/

These Quicksilver Mid Mono amps are perfect for tube rolling. You can get them new for 2 grand !
http://quicksilveraudio.com/products/midi-mono/

piramis
  Tube amplifier suggestion for 101 dB speakers
Tyler Acoustics PD30

 
You've got good efficiency, so you don't need a lot of watts, 50 would do, but these speakers are spec'd by the manufacturer at 4ohms nominal, and you can bet they go down to 3 or maybe even 2ohms somewhere. So I would look at tube amps that have a 2ohm output tap as well as the normal 4 and 8.

 Roger Mojeski's Music Reference RM200 amp has this.
 http://www.ramlabs-musicreference.com/music_reference_rm-200_hybrid_power_tube_amplifer.html

Cheers George

Mike Sanders of QuickSilver uses JBL horns with woofers I think they are at least 10 " woofers ( 4 in each speaker unit). I have QuickSilver mono 60 and just love them or  if money is no object you can go for the EAR 509  mono or Viva Solista 18 watt Set integrated amplifier , my speakers are 97.5 efficient Daedalus Poseidon

QuikSilver mono 60 's or Don Sach's KT-88 Kooteney amplifier ,

I had been happy with Rogue Cronus Magnum II for 6 years.

With tube rolling it is a very good amplifier.

ST100 is very similar to  Cronus Magnum II.

I can also recommend the Line Magnetic 518 integrated also.

I agree with the Rogue ST-100 recommendation especially with Gold Lion KT-77 tubes for 70 wpc.  Also suggest you not take speaker manufactures specs at face value as they have been known to fudge them quite a bit.  For example my Spatial M3 TM's have a stated efficiency  93 db until you look at the fine print a see that that is only over 300 hz as it's twin 15 inch woofers are no where close to 93 db efficient.

You could get a Rogue Stereo 100 100wpc tube amp for around 3 grand.  It uses KT120 output tubes and it is a tube rollers dream.

Even if your speaker has a high efficiency, I do not recommend small power SET amplifier to drive two 15 inch drivers.

You may try this one as a starting point.

https://www.audiogon.com/listings/lis9b270-line-magnetic-216i-tube

Later if you can afford more, then I recommend Line Magnetic 508.

https://reverb.com/item/17478397-line-magnetic-508ia-single-ended-triode-vacuum-tube-2018-black-clas...

I am happy with  Line Magnetic 508 for 6 months.

https://forums.stevehoffman.tv/threads/new-line-magnetic-508ia-integrated-amp.542333/