A push-pull tube design and Single-ended class A designs


Between a push-pull tube design and Single-ended class A designs amp, is Single-ened class A better in sound quality, why?

Its not that simple!!

SETs work really well if you have a speaker efficient enough to really take advantage of their strengths. If you don't, you are wasting the money invested in the amp! SETs should be used such that only about 20% of their total power is invoked at any time during your listening session. If you use more power than that, the distortion gets high enough that the amp will be pretty distorted on musical transients. The kind of distortion present (higher ordered harmonics) is used by the human ear brain system to calculate the volume or loudness of the sound (Loudness Cue). So the result is that the loudness cues will ride on the transients, causing the amp to sound very 'dynamic'. This is why you hear tales about how SETs are so dynamic for their otherwise low power. Its distortion masquerading as dynamics.

Essentially when describing dynamics, you can replace the word with 'distortion' and not change the meaning of the conversation.

OTOH, at lower power levels the distortion becomes unmeasurable, quite unlike that of most push-pull amps. This is the source of that 'inner detail' for which SETs are so lauded.

Push-pull amps do better at higher power levels (having less distortion), and so sound smoother when you push the system harder. In addition, they often have more power and wider bandwidth, which means you can run less efficient speakers that might have more bass response (typically the kind of speakers you need to work with 90% of all SETs need to be over 100db 1 watt/1 meter for best results- this means they won't be playing that bottom octave and may be missing some of the octave above that as well).

We've not described the effects of loop feedback, which is a conversation on its own, but many P-P amps have it while most SETs do not. Feedback can cause the amp to sound brighter due to bifurcation of existing distortion into higher orders, which the ear treats simultaneously as brightness and harshness.

If the Push-Pull amp is designed properly (no feedback and no separate phase splitter circuit), the distortion will also decrease with power to unmeasurable, but IME these types of Push-Pull amps are rare. However if that quality is present its sort of like get your cake and eat it too- you have the advantages of SET (good lower level detail) without the power or bandwidth limitations. 
As with most things it's not the topology it's who's implementing it. There are good and bad examples of both types of amps.
Which is better will depend overwhelmingly on your chosen speakers, it really comes down to that. I've been using a 300b SET amplifier for over 6 years and there's no going back. Prior to this I'd use various push pull amplifiers for about 15 years. I've heard many different push pull amplifiers and like everything else there is a hierarchy of performance. 

You'll have to get a SET built  to a high quality standard (output transformers and power supply ) with quality parts. If you couple a SET of this caliber and match it to an appropriate speaker, I believe that you'll be very happy.  I have more purity of sound and naturalness of music presentation than ever before. That's just my experience,superior natural character. 

There's no doubt that you can also develop a terrific sounding system utilizing push pull amplifiers, again it depends on speaker choice and your individual taste and objectives. 

Thank you so much atmosphere, jond, and charles1dad.

I was looking into purchase Cary SLI-80 integrated amp for my Sonus Faber Venera 2.5 and read somewhere that Dannis Had is the founder of Cary and he designed SLI-80 was retired and now he is doing Inspire amp at reasonable price.

So I was thinking between Inspire KT-88 Fire-Bottle amp will pair with my ARC LS7 preamp or to do Cary SLI-80, which would be better for my speakers. Cary SLI-80 is a Push-Pull but Inspire is Single-ended class A.
Based on the specs of the speaker an SET is out of the question!! You would want a speaker that is at least 10db more efficient with most SETs made. The recommended minimum power is 40 watts, which is a **very very** large amount of power for an SET!

The best SETs seem to make no more than about 7-10 watts; the turly best of them make considerably less (the less power they make, the better the bandwidth, but as you can see the greater efficiency is needed in the loudspeaker).
Given your speakers, the Cary integrated amplifier would be a more satisfactory match. IMO  the single ended Inspire isn't powerful enough to manage your speaker's load demands. Technically this amplifier is a SEP (single end Pentode)rather than a true single ended triode (DHT). The Inspire is built with cost restrains in mind. It doesn't have premium transformers or an exceptionally stout power supply. It's a nice choice  for very easy to drive speakers however.
Thank you so much.  :)
Cary SLI-80 integrated amp would be the better choice for those Sonus Faber Venera 2.5 speakers, IMHO.

I had speakers with about the same measurements as yours, and tried one of Dennis' KT88 Fire Bottle SEP (Single Ended Pentode) amps. I really wanted to like it because it was so conveniently small, and inexpensive and I thought it would mate well with my Had designed Cary SLP-98P F1 preamp. However, it did not turn out well at all. Soundstage was very compressed sounding and rolled off sounding on highs and lows.

Dennis was very helpful, and did send me quite a few tubes to try to help open it up. In the end, nothing seemed to work. Dennis is a great guy though, and has an infectious love of this hobby. He did refund my money, so I have no qualms.

I did read of others who loved the amp, some with speakers that were even more difficult loads than mine (90 dB, 8 ohm). This is a strange hobby indeed.
There is no such thing as the best in this hobby. It all comes down to personal preference. Based on my experience. SET and single driver speakers excels in jazz and classical music but sucks in other genre. I don't listen to classical so my choice is Push-Pull that gives me the slam I like specially with rock and r&b and still able to enjoy the sweetness of jazz. Hope this helps.
Thank you Sir.  Now I know which to get.  
Can you guys give me some sample of Speakers that good for Single-Ended Class A amp?

eddy1 never buy an amp first and then try to find a speaker to fit it. Go to Axpona or Colorado show and see what speaker you love then match the amp push pull or single ended to go with it.
The suggestion of going to a show is a good idea,  you need the broad range of exposure to get an example of what appeals to your ears. Try to seek out higher efficiency speakers  (say 92db and higher ) and higher load impedance (say 6 ohms or above). Avoid speakers that dip to low impedances (especially in the bass region). You can build a system beginning with the speaker  (most common approach )or begin with an amplifier.  I've done it both ways successfully. Either way one is going to have to match the other component. The key to satisfying SET amplifier use is getting a speaker with a compatible load to drive. Take your time, read and go out and listen. Key points for good SET selection are high quality output transformers and strong power supply, these are essential factors. Take away point, steer clear of inefficient and challenging speaker loads. SET will sound exceptionally good with multiple music genres with the right speakers. That's been my experience the past 6 years. 
Generally speaking, if you want to explore what SETs really have to offer, higher efficiency loudspeakers of easy impedance (8-16 ohms) are preferred.

A great speaker would be the Classic Audio Loudspeakers Hartsfield reproduction. Its about 105 db and very wide range for that efficiency!

If you are on more of a budget I would consider a full-range loudspeaker like a Lowther or PHY in an open-back cabinet or baffle.
Thank you very much jam, charles1dad, and atmasphere.

charles1dad, I really love to go to the show but where can I get the info regarding show information. I am in San Bernardino county, Los Angeles county CA.


There's an annual show in Newport, CA.(usually late spring-early summer) it's reported to be a really good audio show.


Thank you Charles.
Hi : have you tried Airtight ATM 211 . They are amazing 


The Newport SHOW, June  3rd-5th 2016, The Hotel Irvine, Irvine, CA.


Thank you fazad and Charles.  I will be there for sure Charles.
I doubt that any of the classic, low-powered triode tubes (300b, 2a3, 45) would work well with your speaker, even in parallel SET configuration (more than one tube per channel).  You would really have to look at a high voltage transmitter tube SET (845, 211, GM70), and well-built examples are pricey and don't quite deliver the sound that is prized by low-power SET fans.

Atmasphere refrained from touting the approach his products use, but, certainly an output transformerless tube amp is something worth looking into.  These can deliver considerably more power and a model might be suitable for use with the Venere.  Good OTLs are very exciting sounding: great dynamics and a lively, forward sound.  I think that kind of presentation would help the Venere. 
Thank you larryi.
s1nn3r is dead right. I was involved in the audio business in the late 1960's and the early 1970's. One of the challenges was helping customers to be comfortable buying what they liked rather than what they had read or been told was best. Taste in sound is at least as personal as taste in toothpaste.