What contributes most to a change in how an amplifier sounds?

Don’t forget how you isolate them from resonance and vibrations. 

Reminds me a bit of the old story where organs of the body are having a fight over who was most important.  Can’t remember what the plot twist was — something like the little toe saving the day.

But the moral was the organs make up a team, all of which is “most important” depending on what is going on.

Hi @emergingsoul ,

This is a good question.I thought about it, to make stuff about tweaks on youtube. But my English is not good enough to do it. English is my 4th language. I am also not a good speaker in general. For me it is much easier to write.

@alexberger 

You need to have a play date with.  @knotscott 

I saw your YouTube channel wondered how it might be you could do a narrative of the types of work you do with your system.  Inspiring to see people with all this knowledge and putting it to good use.  Very very technical stuff.

@knotscott

You certainly know your way around the inner workings of the mystery boxes in an audio system and how cool to have you as a neighbor. So much knowledge between your ears.

Seems like the power supply and transformers, no surprise, dominate how an amplifier sounds. I’ve always wondered why amplifiers don’t have a second Power chassis but this clearly would be impractical. Capacitors certainly influence the rebustness of amplifier dynamics and I would guess these wear down overtime.

I, like you, pursued biamping, and I use a MC 901 pair from McIntosh. a more safe approach for me by ensuring added amplifiers Will get along and avoids additional interconnects. I upgraded all the small tubes with NOS telefunken but have continued with the same power tubes I'm not sure how much these will influence sound but quite a price tag to replace them all.  

You have a nice size room and a lovely space. My amplifier does quite well in a 20 x 16 room but is deserving of a much larger space.

Hardly any mention of AC cable.  It makes a difference, and it's something users can often change, unlike most of the other components.

I had a 300b integrated SET amplifier from 2005.

I tweaked a lot of different things:

1. Interstage capacitors.

2. Tubes working points.

3. Cathode and load resistors.

4. Power supply capacitors. Including increased value of capacitors from 100uf up to 3500uf per each tube b+.

5. Cathode capacitors. Including increased value of capacitors from 100uf up to 100000uf.

6. Added interstage transformer for driver and input tube.

7. Added a separate power transformer for drives and input tubes.

8. Build a new 300B SET with external power supply.

9. Changed driving tube from 6f6 to 6v6 and 6L6.

10. Changed output transformers.

I didn’t try to do:

fixed bias, voltage stabilization, SRPP, choke load (LC coupling), direct coupling and many other things.

In SET amplifier:

1. Output tube.

2. Driver tube.

3. Coupling between stages (transformers and capacitors).

4. Cathodes (cathode or fixed bias, cathode bypass capacitors size and quality, resistors).

5. Signal transformers quality. Output, interstage, input.

6. Power supply. Fist capacitor quality. B+ capacitors quality and size. Voltage stabilization. Power transformers and chokes.

My experience is that the color of the housing is the most influential determinant. A shiney black case produces less harmonic distortion. And I agree that a good on/off switch can make a critical difference. 

Looks….If the amp looks ugly it will play as such. LOL

One might also include OTL. 

The meters:  Instantaneous is far superior to averaging.  A common misconception is the color of the backlite illumination matters.  This is a myth.

Without a doubt the power supply is critical. There is also the input stage, which if not done well will result in the output stage amplifying distortion and artifacts. 

Audio Research’s WZ Johnson believed that the transformers were the make of break component in the quest for audio excellence.  

I would agree with @helomech on distortion signature. When people describe sound attributes of a power amp, it's likely the sonic signature the manufacturer was designing for. 

$

@thecarpathian 

😂😂😂👍🤦‍♂️ CLASSIC 

In a single-ended, no-feedback tube amplifier, it largely comes down to the output transformer.  Nothing else can make up for a poor OPT.  In a push-pull amp there's a bit more leeway because the OPT doesn't have to handle a large amount of standing current due to the cancellation.  Add global feedback and you can turn a pig's ear into a decent silk purse, as the saying goes.  But any tube amp is still going to benefit from quality iron.  As others have said, the power supply, the circuit design and other components can all make a difference.  Oh, and the power supply time three, as perkri says. ;-)

Power supply, quality of components in critical places, feedback, bias and even chassis design and quality. 

Power supply 

Power supply

Power supply

1- whoever is listening.

2- location, local, location.

Distortion signature and output impedance. 

Everyone forgets the power supply. It isn't as sophisticated as the amplifier circuit itself but it's actually the direct electrical connection to the speakers whose impedance interacts with the amplifier to great affect. The thing we think of as the amplifier is basically a valve that opens and closes the power supply supposedly as an analog of the input signal. So the better the amplifier does that the closer the output is to the input albeit larger. But that assumes the power supply is robust and pure. If it isn't even if the amp is accurate it's varying a changing source of current and the result is loss of fidelity.

It turns out many circuits are pretty good but power supplies are expensive and you can cheat with little or no change in the classic measured specs. The only thing that changes with a so so power supply is the sound. Power supply is a major factor why costly amps sound so good. There's money to make pretty good power supplies. But I suspect even 6 figure amps can be improved with even better power supplies.

The transformer.

@bigkidz , I remember a conversation I had with John Barnes (may he rest in peace) of Audio Unlimited quite a while back.  He was talking about a couple of tube amps and I forget how he exactly worded it, but it was to the effect of when when comparing amps and you separate the wheat from the chaff it is the transformer that makes the difference.

The transformer is the beginning to great sound.  It has to handle the requirements of a recording.  If you think about it, why do different amplification from the same manufacturer sound different or handle music differently?  Quick Silver just stopped making one of their amplifiers because they could not source the transformers any longer.  We used to use Plitron transformers but they now require a minimum order of 100 pieces.  Designs are not new so depending on what you are looking for, a design is important to the sound and cost.  Power supply is the key to great sound.  That needs to filter AC noise, handle dynamic swings, etc.  Then capacitors and resistors have an impact.  Tubes vs. SS is personal preference.

Happy Listening.      

The loudness button.

Output impedience.

If you follow the graphics in Stereophile, you see that the higher the output impedience, the greater the variation in frequency response based on a real life speaker load that is not a simple resistor.

A good design  helps a lot. 

Just like an entire audio system, an amplifier is a chain of circuits and parts that’s only as good as it’s weakest link. At some level, everything matters, but many folks feel that it all starts with the power supply.  In the case of tube amps, I can't help but think the quality of the output transformers is pretty important. 

My amps started as Dynaco 70s, then got a boost in the power supply that helped. Later on they got modified with the VTA circuit boards that address the power supply and audio circuit even further, better caps, etc....a;; very audible improvement with the same output tubes and transformers. Later I changed the output and driver tubes, then upgraded the rectification to SS. All made audible changes that I felt were upgrades. When I finally bi-amped the system in a horizontal configuration, the Dyna/VTA amps went from seeing a 4 ohm load to an 8 ohm load where the tube amps only drive the midbass and tweeters, and that made another very audible improvement. All of these changes contribute to what I’m hearing now, but I can’t say that any one of them was more important than the others. They all add up, and they all matter.

FWIW, I’ve always preferred them in triode.

Whether the amp is wired in an ultrlinear or a triode circuit.  

You didn't mention capacitors, but you should have.

The speakers with which they are paired.

The on off switch.