What contributes most to a change in how an amplifier sounds?
Amplifiers include tubes (if not solid state), big transformers, lots of internal wiring, Power supply, cabinet, gain controls if you're lucky, connections for incoming and outgoing cables, Computer chips, Control panels, semiconductor boards, design choices, age, etc.
Of all this stuff, what contributes the most to a change in how an amplifier sounds?
About twenty years ago I bought a pair of old, used Altec-Lansing 1568A mono amplifiers in nice shape, they had spenent their lives in a rack.
Those 1568A’s are simple, lightly stressed designs, made to run 24 hours a day, using two EL34 tubes in a push-pull configuration to deliver a clean 40 watts.
They also have some of the finest transformers ever put in an amplifier, second only to the legendary output trannys found in the Harman-Kardon Citation II.
Any tube amplifier made today, regardless of price, except for some insanely expensive Ongakus, has transformers that cannot hold a candle to those on those Altecs and the H-K Citation.
But the Altecs also had anemic and primitive power supplies. Too simple.
Upgrading a tube amplifier power supply is really not too difficult, and these had plenty of room to work in.
So I went to town on these, replacing the PS caps with new oversize electrolytics with poyptopylene bypass caps.
I also also added a filter choke. A slight hum disappeared completely, All the signal caps were updated with Polypropes. All the resistors were replaced with new carbon films
Finally two NOS sets of Philips EL-34’s finished the job.
Those old Altecs put my McIntosh MC-60’s to shame. Greater slam in the bass, smoother mids, and the highs were just plan gorgeous, silky and detaled, into my JBL C50/S7 speakers.
I soon sold the Macs for $2000, and the total cost of those Altecs including the mods was about $700.00.
Downside: These Altec 1568A amplifiers are just plain ugly to look at.
Just put them somewhere you don’t have to see them.
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.
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.
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.
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.
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.
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.
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.
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. ;-)
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.
@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.
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.
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.
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