What is the consensus of best amplifier topology TODAY??

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Hello...

Well here we are, well into the 21st century...
Internet forums-discussions abound... Tons of info and opinions out there.... can get a bit confusing.
It cuts both ways.
So many have come and gone.. Some even pretty good..
So many "fads" come and gone too...

So, What, TODAY (with alllll the hindsight available) are thought to be the best Amps..
(basic power-amp)..
Which topologies/designs/etc..
Best sounding, I mean... not nescessarily best in some theoretical sense..

More to point.... which of those can be implimented..
Kits, circuits, parts, etc. too plz....

TIA!
Greg
 
Imho, Class-A will always reign supreme, tube or SS. This comes with large power consumption if you need double-digit watts though.

My vote for solid state (as per the forum) would be Nelson Pass' SIT-2. Technically a topology of Class A.

For something more "normal" and versatile, Class-D is getting better and better everyday. The TPA3250 and variants have incredible specifications by generally accepted standards.

I personally don't go by normally accepted standards though, which is my reasoning for the SIT-2 for SS and why I own a Decware SE84UFO SET amplifier myself :).
 
Last edited:
I'm fairly new to this but am curious about the OP question as well... I can fully appreciate no "best" amp ever existing and understand the multitude of variables involved with system synergy (not even considering the huge subjective - objective/measurement debate)

Still, as I'm absorbing everything I can with this new hobby it would be great to get a read on "where things are" with the current state of amp tech (not that the newest is always best)

I'm very interested on folks thoughts about a hypex nc500 with 994 op amp--is this the *best for most* searching within in class D? Tho open to any input...
 
ClassA is the gold standard I agree. But apart from headphones its quite impractical for most users. ClassD is the next best bet ISTM, rather than the still mainstream classAB.

How much power do you need @blippio? Ncore is highly regarded but might be overkill power-wise.
 
@abraxalito: I'm looking to drive Boenicke w5 clones @4ohms... the designer says they love power but the specs on the nc500 into 4r scare me at 700watts (I believe)... I don't listen to music at crazy volume anymore but I'm guessing 100 would be plenty. Or 220/221, whatever it takes :)
 
Imho, You'd be hard pressed to ever need more than 64 Watts/ channel as an absolute worse-case scenario, and that's extremely conservative.

For most living rooms with most speakers, I believe 8-16 watts will be adequate even with inefficient speakers (84dB/2.83V/1M) for most people. Unless you like getting extremely loud. I think most people would be shocked by how much power they really use at their normal listening levels.
 
There's no consensus on best amp topology...

Which topologies/designs/etc..

It is important to understand that we need to set an objective first in order to be able to find the right processes (the topology, the parts, etc.). "Best amp" is not specific enough for a design objective. Money, is always an important criteria. If we want the absolute best amp, then be prepared to purchase very high current transformer (and heatsink), matched top quality transistors and many more.

The smallest entity of an amplifier is a transistor. For a good amplifier, good transistors is a must. Unfortunately, transistors are produced for other purposes than audio such that best transistors are usually rare.

We can start from choosing our favorite input transistor. If we want the high impedance and low noise JFET as the input transistor, then the following stages (which dicates the topology chosen) should be designed accordingly. Finding matched P and N channel JFET is hard/expensive, so either SE or LTP left to be used. High trans-conductance JFET is also hard to find, making ordinary JFET design unfavorable, especially when coupled with low trans-conductance output stage and a speaker with low impedance.

LATFETs have very low trans-conductance. It is so low that THD is not usually the first priority when designing with them. The dual LTP is the 'de-facto' topology as advertised by Hitachi (0.01% at 100W). Also the paralleled 2 or 3 pairs. One of the best 'topology' for LATFET is what has been implemented by Goldmund (dual LTP). Equal performance (but probably not similar) can be easily achieved with CFA topology.

BJT transistors have very high trans-conductance. This makes THD the first priority when designing with them. If you can reach 0.001% or below, then do it (it is a must).

Darlington BJTs are unique because they are designed usually not for audio. They are not flexible and not useful unless you already have them on hand. For high current they are 'difficult' to compensate. But because they can run well with very limited current, they can be useful if you need to use small transformer and small heatsink.

From all the topology, I found that CFA is very useful/flexible and can always be used with performance above average.

Below is a quick drawing of a darlington BJT in a CFA topology. It is so rough but the AC performance is so good (CFA has wide bandwidth). The darlington is a Sanken 2SB1560 and its complementary. (I usually use around 19mA of the output stage and 8mA of the driver stage). It is not yet finalized (I haven't even seen the PM/GM) but I will build it, probably starting with the schematic as is.
 

Attachments

  • VSSA Darlington.png
    VSSA Darlington.png
    60.4 KB · Views: 1,805
No such thing... however, some thoughts

What does the "best" mean?
Examples:
- lowest THD?
- lowest IMD?
- best harmonics profile?
- highest slew rate?
- best energy efficiency?
- highest stability?
- best versatility in driving different loads?
- lowest s/n ratio?
- lowest output impedance?
- lowest phase shift?
- widest bandwidth?
- highest reliability?
- longest lifetime with no repair?
- smallest size / lowest weight?
- biggest size / highest weight?
- lowest heat dissipation?
- best look in the interior?
- least expensive one?
- most expensive one (important for some users :))?
- least part count?
- highest probability of survival in case of nuclear explosion? (ok, just joking ;))
- best sound? Does anybody know what that is? :confused:
- I can continue :)

The "best sound" is normally the most important criteria, but the least objective one at the same time, strongly dependent on individual taste.

Class A - the key advantage is "no crossover distortion" with the price of rather low energy efficiency - not an advantage for me as there are other ways of achieving "no crossover distortion", with much better efficiency in place.

If we would know the "recipe" of the best amplifier topology - we would all use it for building the best amplifiers :D

OK, still - for me, the key design principles are:
- THD/IMD - low enough with good harmonics profile, especially with regards to high order components.
- good dynamic performance - square wave at 20KHz looks like a square.
- good s/n ratio.
- high output current capability for being able to drive different loads, including low impedance and high capacitance ones.
- unconditional stability.
- high overall reliability.

Ways to achieve these properties:
- current drive in most of the stages within the circuit - common base cascades, controlled current sources, etc.
- high linearity of each stage open-loop.
- combination of moderate feedback and feed-forward error correction, multiple loops, not necessarily nested ones.
- simple circuits, however simplicity is not the end in itself - if more parts are required for better performance, let there be more parts.
- "constant power" concept in voltage gain stages - not always strictly followed, but staying at least close to it.
- very careful, thought-through build design - in many cases, vitally important for expected performance.

Sorry for "many letters" :p Hope it helps somehow.

Cheers,
Valery
 
I am not saying it is the best, but I am saying it is may favorite setup so far. I like class A designs and specifically all Triode and only two stages. I find that optimizing the operating points I can get low enough distortion without any means of local or global feedback, the intrinsic feedback within Triodes is sufficient. I get all second harmonic -40db @ 1 watt, which is something around .01%. The majority of listing I do is much less than 1 watt due to my very efficient horn speakers. This allows me to get away with using low power Class A amps.

I know people will argue this is too much distortion to be considered high fidelity but I believe sound quality doesn't just boil down to low distortion. I will happily trade the low distortion for increased stability which allows me to listen for longer periods without fatigue.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.