Pure Class A SS vs Tube Amp

The hiss levels produced by some amps which may be perfectly fine with say 90 db speakers could very well be bothersome with 102 db speakers.

@almarg That's usually more of a preamp thing. Most amps are plenty quiet to be fine on a speaker of 102dB.


@lordrootman  One thing to be aware of is that the distortion of an amplifier makes a much bigger difference when dealing with a high efficiency loudspeaker! Solid state amplifiers are well-known for brightness and harshness; this is caused by the higher ordered harmonics they make of which I mentioned earlier. One thing I did not mention is how keenly sensitive the ear is to these harmonics- this is because it uses them to sense sound pressure over a 130dB range. So keenly sensitive is an understatement. That is why the 'very low' distortion of many solid state amps is nevertheless audible.


Most push-pull amplifiers, whether tube or solid state, have a character where there is a certain minimum power below which distortion actually increases. There are only a few push-pull amps where this is not the case (ours are some of those few). This is the origin of that 'first watt' thing, where there first watt has to be a good sounding watt. On your speakers this is going to be critical. On that account 99% of all solid state amps should be ruled out; if you really want to go solid state your options are few. The Nelson Pass First Watt amps are your best option in that regard.


But if you go with tubes you have a few more options! You don't need a lot of power (25-30 watts at the most in most rooms, provided its musical power). A lower powered tube amp with high resolution will bring you more satisfaction. I think it a very good idea that you do a shoot-out, since you probably want to get the most out of your speakers! Do an audition of some of the top contenders (tube and solid state) and I think you will see what I mean.


One further note- the amplifier will not need a lot of gain- 20dB will be plenty. We have quite a few horn customers; normally our amps have about 25dB of gain but with a simple adapter plug we offer, the gain of our amps can be reduced to about 15dB which knocks out a lot of the noise floor that you will encounter with many preamps. For this reason, many low powered SET amps have only about 15dB since they are intended to operate on high efficiency loudspeakers.

The bottom line here is take your time. What is important is that when you play the system, it convinces you of music and you want to spend time with it- that is what the investment is for. Matching the amplifier to horns is always critical, but if done properly the payoff is huge. I recommend bringing in your significant other (as long as the two of you enjoy similar music) as this whole thing works better if both of you enjoy the presentation. Above all- have fun!

... my new preamp Michi P5 is class A design

@glennewdick makes an excellent point about usable volume control range. And that is a particularly important consideration in this case because the Rotel Michi P5 preamp has high gain. According to my calculations its gain is at least 16 db, and it may be considerably more than that depending on the combination of RCA and/or XLR inputs and outputs that are used. But even 16 db is well above average for the gain of a line stage.

Power amp gains generally tend to be in the area of 25 to 30 db. Your A21+, for example, has a specified gain of 29 db. But given the high gain of the preamp and the high efficiency of the speaker I think it would be prudent to avoid power amps having gains of more than about 20 db. (The gain of the XA25, btw, is 20 db; many of the First Watt amps have gains that are significantly less than that, which would be fine in this case).

Power amp gains are often not specified, but they can be calculated to a good approximation from the sensitivity spec that is usually provided, in combination with the specified maximum power ratings. Online calculators may be available for that purpose, or you can post back if you’d like to me to described how to do that calculation manually.

Finally, btw, virtually all preamps (and other line-level or phono-level analog components) operate in class A, even though some manufacturers trumpet that as a selling point.

Good luck. Regards,
-- Al

I could live with a Rogue Aidio Cronus Magnum III, it is quite nice. If you haven’t owned tubes, I recommend the experience. If, like me, you are married, have lived with tubes for decades, and are over having to buy new power tubes (especially, pre tubes are less of a pain), and losing resolution to noise, get a Luxman 550AX II and be done with it.

"...first 6 watts is pure class A sounds really good I’m just wondering what I’m missing i guess I need more class A..."

With speakers @ 102dB efficiency, of course depending on your room size, I suspect most if not all of your listening is within the class A envelope.  

I’m very please for great response from everyone thanks appreciated 
after reading all the comments and suggestions  I have decide to separate my 2 channel from home theater  
now my new preamp Michi P5 is class A design well I don’t know much about class a preamps I just love the looks lol
I think passlab XA25 first Watts J2 Shiit Aegir and some monoblocks are in consideration I need to read more 

Funny you should ask as I just went thru this transition.
While my Cary amp was in the shop, I ran across an inexpensive
pair of pass diy monoblocks so i bought them as a filler.
They are a whopping 7wpc of pure class A. I immediately knew I
was either a monoblock guy or class a guy as they sound was
so much more detailed -I had to have it.
My Tannoy speakers are rated 94 sensitivity and even so at full volume
you did not need to leave the room.
So yes they are underpowered for a large room or orchestral music.
I have worn out ears and do not listen loud anymore- 75db max.
I sold the Cary and bought a 25wpc class a amp that I am breaking in
as i type. Not missing the tubes. I may buy a tube preamp though.
Your horn klipsch speakers may get a bright with all class a. The right
cables would likely overcome that. Good luck!!

almarg FWIW I suspect that the solid state Pass XA25 I use would be fine in that regard

lordrootman OP
@almarg thanks you’re exactly right is rated 102dB
I will check pass lab out

I would also check out for "value" the Schiit Aegir 20w of Class-A which Stereophile measured at 28w, "low noise" and also far cheaper than the Pass would be. https://www.schiit.com/products/aegir and you don’t like it within 15 days you can send it back

I was pleasantly surprised by the Schiit Aegir’s measured performance. It is a well-engineered amplifier at an affordable price.—John Atkinson

 And because your KLF30’s are bi-ampable, you could bi-amp them with two Schiit Aegirs in vertical-biamping.
https://www.classicspeakerpages.net/IP.Board/uploads/monthly_2016_03/7_Vertical_Bi-Amp.thumb.jpg.672...

Or one Schiit Aegir for the mids and highs and a Schiit Vidar for the bass horizontally bi-amped. (may need a Schiit Sys to even out the gain)
https://www.av2day.com/wp-content/uploads/2014/05/biamp1.jpg

Cheers George

I use a Schiit Aegir.  It sounds wonderful.  20W

Also, Monarchy Audio.  Been in business a long time.  Pure class A.  Stereo and Mono block versions. Simple circuit with no feed back.

Pass Labs and First Watt.  Nelson Pass is a legend
I saw a completely rebuilt Krell KSA50 a while back for $2000 that would have been great. 

Sugden A21Se, beautiful tube like sound, inner detail, and bass control. 30 watts into 8 ohms, 40 into 4 ohms. Single ended class A. Drives the Tannoys wonderfully. Using QED Silver Anniversary XT BiWire cables. On a Tangent, my Main source is a Pro-Ject the classic with modified Evo machined aluminum subplatter running a Hana EL moving coil with Alnico magnets. Pure heaven to my ears. The table is $1000 plus $475 for the Hana, a hide in the sound leather/suede mat, and a record DR clamp, using Atlas Element Integra turntable interconnects and ground. All this running into a Pro-Ject Tube box Ds2 tube phono stage (400 ohm loading @ 60 db gain). I mention the turntable and associated upgrades in the event someone wants to put this together for themselves...it Is truly contributing to the great sound I am hearing. I think the QED cables, being the only thing in the system containing a trace of silver, helps to offset the warmth of the amp, speakers, and tube section of the phono preamp, complimenting them beautifully. 

I have 100db speakers as well also Klipsch new heritage line. I have tried a SET 300b based tube amp and that sounded wonderful (8wpc, by the way it was a Finale Audio 300b integrated). I have tried a class A SS from Luxman also very nice if not a little too much power (50wpc). I've also used class AB Sansui amps (AU 9900 and AU 5900 totally refurbished) and they were surprisingly good, actually this is a very good match IMO for Klipsch speakers. 

I my experience the biggest issue I have run into with speakers in this efficiency range is usable volume control. You really need to match your amp and preamp together In this regard or you could end up with no usable volume control range. for example If you mismatch the pre-power you could end up with a volume control that turns a few deg only before your maxed out this is an issues because you end up using the very bottom 5% of the volume pot-etc. this is not ideal. 

If you want a tube amp with very good build quality and parts I'd highly recommend Finale Audio -Triode labs out of Toronto they make some very good low powered tube amp and you do not need to spend close to your budget well you could spend it and more but not needed. 

I think someone recommended First Watt another very good choice IMO due to the build quality and low power class A output. 

el34 tube and 45 tube amps  also sound really good with the Klipsch speakers. 

you don't need more then a couple watts, literally 2wpc (that's what you get from the SET 45 tubes by the way) can do it. 

glen 

Not so. Think of it as an "equation." Amplification on one side, speakers on the other. One does not dictate 'over' the other. They are "codependent."  Hopefully not pathologically so. : )

Your speakers dictate what amplifier  type

@almarg  thanks you’re exactly right is rated 102dB 
I will check pass lab out
my current amplifier parasound A21+ Is 300 WPC at 8 ohms first 6 watts is pure class A sounds really good I’m just wondering what I’m missing i guess I need more class A lol 

Your speakers dictate what amplifier  type , with tubes youhave so many options true Single ended which is under10 wpc which is the purist , 2 tubes 
any more is a going into class A ,then triode, pentode, tetrode Ultralinear. Even a OTL amps 
it is not that cut and dry  and each power tube type sounds different , 
as well as the small tubes,and rectifier tubes.  That is why everyone likes something to match their Audio taste ,and music type .having several amps
is always a bonus,

It appears that the KLF 30 is actually rated at 102 db/1 watt/1 meter, and given the horn loading of its mid-range and high frequency drivers I suspect that rating is reasonably accurate.

A concern such high efficiency raises is that the noise performance of the amp that is being used becomes especially critical. The hiss levels produced by some amps which may be perfectly fine with say 90 db speakers could very well be bothersome with 102 db speakers.

FWIW I suspect that the solid state Pass XA25 I use would be fine in that regard, as it is extremely quiet with my speakers that are spec’d at 97.5 db. I have no idea, though, how its very transparent and somewhat tube-like sonic character would synergize with the sonics of the KLF 30. But in any event, before settling on an amp it would be prudent, IMO, to try to verify that others have used the particular amp successfully with comparably efficient speakers.

Good luck. Regards,
-- Al

@Lordrootman, If within your budget, look no further than LTA , David Berninig  design, extremely long tube life and many informative reviews. The best of both SS and Vacuum tubes all in one. Can’t imagine making a mistake here. I’m using their new ZOTYL integrated at 20w and my 90 dB efficient REF 3A GV’s (way loud enough in a large room,) and my new PAP Quintet 15’s are for me blissful, the best I’ve had for reasonable money on both accounts. Don’t miss it and great folks for support. Best Dave H

Id suggests you look into the Atma-Sphere MP60 OTL mono block amps, Enough power reserves for what you need. They have a magical quality to them when setup properly. 

Absolutely. Might be superior. : )

Thanks everyone for great recommendations
can I run tube amp with SS PREAMP?
are they going to make any difference

Or one of the Raven integrated.  A strong alternative to Rogue and PrimaLuna.

Of course, being a current Luxman owner, if you could get that in your price range .... :)

But do listen to the Rogue integrated too.  It may be jusut the ticket.

I liked the pairing of my KLF-30s with my Rogue Audio M-180 tubed monoblocks.  I haven't had any class A amps to compare to, but that sounded really good.

In regards to the comments about wearing out your tube amps in a dual use system, I often don't turn on the amps if I'm just watching TV.  I use my five channel amp that powers the 4 surround speakers and the center channel and just listen through the center channel.  When I do engage the M-180s for movies, there's no lack of dynamics.

Lord, you can't go wrong following Ralph's advice. I use separate amps for HT, all Class D Audio, built from kits. I have a separate two channel line stage with HT bypass, and a couple of other tube amps (SET 300B, and SET 845 amps) for use with my two channel system.

I very much enjoy my system, and I do, at times, run my HT system using my tube amps, and don't feel like I'm missing anything. 

Regards,
Dan




 

lordrootman,
I have not heard the KLF 30's.
I agree with charles1dad, I would not consider tubes if your intention is to have the amp in use with a homes theater set up. I was strictly thinking along the lines of a two-channel music system which is what I have.

 I read somewhere that tube don’t have dynamics for movies thanks and I appreciate through KLF 30 fan

@lordrootman  What you read was misleading. Dynamics should come from the signal, not the amp. As long as the dynamic range is within the power capacity of the amp (and with your speakers this is easy to achieve) the dynamic range of either tube or solid state will be exactly the same.

Now there is a complication when dealing with dynamics! Most audiophiles use the term to describe higher ordered harmonic distortion, because those harmonics are used by the human ear to sense sound pressure. So if some are added by the amplifier, it will tend to sound more 'dynamic'. But that is really distortion masquerading as dynamics. The brightness of solid state is caused by these same harmonics. This is how tube amps tend to sound smoother- its all about distortion. The exception to this is SET amplifiers- when driven harder, they tend to make higher ordered harmonics but mostly on transients at first as the power is increased. When the loudness cues to the human ear are appearing on transients, its interpreted as 'dynamics'. But a sound pressure meter will reveal what is going on- the SET will sound louder at a lower power level than an amp with less distortion playing at a higher power level.

@lak my only little concern about tube is maintenance and also my two channel is part of 7.2 homes theater set up    I read somewhere that tube don’t have dynamics for movies thanks and I appreciate through KLF 30 fan 
how do you compare KLF 30 with upgrade against forte 3 ?

Thanks everyone for great response 
@jyprez plinius SA is great especially option to switch to class A or AB
but I think the upgrade and also special dedicated line is little hard or who can do the upgrade for me ?

I own both a class A SS amps and a class A tube amps.
I owned the Klipsch KLF 30 (unmodified) and one set of speakers I currently use is the Klipsch Forte III's.
While both amps sound very good, I give the edge to the tube amp.
I believe if you stay with a major brand name that has a good reputation you can't go wrong. I prefer not getting into suggesting manufacturers at this time.

I've never heard any Pass Labs amps, but would love to try a XA25.

"...I’m trying to decide pure class A or Tube amp..."

There are lots of tube amps that run in class A. Look for single ended triode or pentode (or beam power) design tube amps. No experience with your speakers but Line Magnetic models with 300B or 845 tubes sound fantastic with high efficiency speakers.

You can get a class A Plinius SA 102 or 103 used (125 watts) for half of your target and have a world class amp that doesn't even need anything like 100dB efficiency. An upgrade/rebuild can be done for around 1500 and then you have a nearly new amp that I have compared with $10,000 amps. 

I heard them with a Rogue Audio integrated.  Not for long, but I thought it was pretty impressive. Others here not so much.

:)