Using a Yamaha AX-570 amplifier in 2021

[Mercay]

Currently using a 25+ year old Yamaha AX-570 stereo amplifier for my headphones and speakers.

I am wondering if there would be a noticeable difference in sound quality if I were to get something more modern?

It sounds great to me, but I do not have much experience with quality audio. 

The headphones I am using are Beyerdynamic DT-990 pro and Sennheiser 560s, but I am thinking about getting a new pair and stepping up in price a bit.

Am I shooting myself in the foot if I use this older stereo amplifier instead of something newer?

Thank you.

[Spuriae]

The headphone output impedance is rated 470Ω (it's not a real headphone output), which would probably produce an extra dB or two of midbass bloat on the DT990 depending on the specific model, and the output power is severely limited into low impedance loads, so it won't drive certain headphones properly.

 

It's lower quality than the average modern motherboard in many respects, but if you can't hear the noise floor, aren't having issues with the lack of power, and prefer a bit of midbass boost, then there's no urgent reason to switch. Whether there will be a noticeable difference in sound quality is really up to what you consider noticeable. Compare the AX-570 headphone output to a smartphone output and see if the difference in sound is appreciable. The difference between a modern headphone amplifier and a smartphone jack are likely to be significantly smaller than the differences between the differences between the AX-570's headphone output and the smartphone jack, at least quality-wise (not power-wise).

 

 

[Entropy.]

4 hours ago, Nimrodor said:

The difference between a modern headphone amplifier and a smartphone jack are likely to be significantly smaller than the differences between the differences between the AX-570's headphone output and the smartphone jack, at least quality-wise (not power-wise).

 

 

(Mostly just adding ont your statement, message is adressed to OP) 

Well, at least if youre looking to compare "clean" and relatively uncolored amps to smartphone outputs, such as the schiit magni or topping l30, for example. There's other options out there that will have pretty large differences, as they colour the sound in various ways. Subjective thoughts or preferences are not really predictable, you may perceive some differences in between say, your smartphone output or something like an apple 3.5mm dongle and another amplifier. 

 

Getting back on trackt, though, if you're content with what you have, and you don't see any issues, it's perfectly fine if you don't want to upgrade. If it ain't broke, don't fix it. 

Edited December 6, 2021 by Brok3n But who cares?

[Psittac]

There is always something to be gained, but as @Brok3n But who cares? said if you're happy with it no reason to change it.

 

@Nimrodor mentioned the ability to drive higher impedance headphones so if you keep that in mind when looking for a new pair of headphones you should be fine, there are many good low impedance headphones to choose from.

 

I'm always told that the noise floor on a stereo amp is the limiting factor but myself it wouldn't bother me, I've got a noisy arse single ended setup from coil whine and I just turn it up and it doesn't bother me (though I'm wanting to implement a solution).

 

What ohm are your dt-990?

[Spuriae]

13 minutes ago, Psittac said:

@Nimrodor mentioned the ability to drive higher impedance headphones so if you keep that in mind when looking for a new pair of headphones you should be fine, there are many good low impedance headphones to choose from.

The AX-570's 470Ω output impedance means that the headphone output power is higher into high impedance loads and lower into low impedance loads. Same reason amplifiers with tube-based output stages tend to work better with high impedance headphones.

 

Typical amplifiers, which have near-0Ω output impedance by contrast, usually deliver more power into lower impedance loads.

[Psittac]

Just now, Nimrodor said:

The AX-570's 470Ω output impedance means that the headphone output power is higher into high impedance loads and lower into low impedance loads. Same reason amplifiers with tube-based output stages tend to work better with high impedance headphones.

 

Typical amplifiers, which have near-0Ω output impedance by contrast, usually deliver more power into lower impedance loads.

so is the complication that high impedance headphones will over draw the amp?

[Spuriae]

15 hours ago, Psittac said:

so is the complication that high impedance headphones will over draw the amp?

The amplifier output impedance creates a voltage divider with the impedance of the headphone, and the voltage over the headphone ends up being V_in*(Z_headphone/(Z_out+Z_headphone)). Assuming an ideal amplifier, headphone power at any given voltage (volume) level is maximized at Z_out=Z_headphone.

 

Because dynamic headphones can have highly variable impedances with frequency, especially at their fundamental driver resonance (usually somewhere in the midbass), high output impedances also tend to boost midbass (subjectively making a headphone sound anywhere between warmer and bloated). As the headphone load becomes inductive at high frequencies, this can also impart some "sparkle", though this effect is usually more subtle. This passive EQ effect is more pronounced the lower the impedance of the headphones is; i.e. subjectively a DT990 32Ω may sound too muddy and sharp from an OTL whereas a DT990 600Ω may sound slightly warmer and have more air, relative to both sounding more similar from a low output impedance amplifier.

Edited December 7, 2021 by Nimrodor
Fixed equation, thanks @H713

[Psittac]

4 minutes ago, Nimrodor said:

The amplifier output impedance creates a voltage divider with the impedance of the headphone, and the voltage over the headphone ends up being V_in*(Z_out/(Z_out+Z_headphone)). Assuming an ideal amplifier, headphone power at any given voltage (volume) level is maximized at Z_out=Z_headphone.

 

Because dynamic headphones can have highly variable impedances with frequency, especially at their fundamental driver resonance (usually somewhere in the midbass), high output impedances also tend to boost midbass (subjectively making a headphone sound anywhere between warmer and bloated). As the headphone load becomes inductive at high frequencies, this can also impart some "sparkle", though this effect is usually more subtle. This passive EQ effect is more pronounced the lower the impedance of the headphones is; i.e. subjectively a DT990 32Ω may sound too muddy and sharp from an OTL whereas a DT990 600Ω may sound slightly warmer and have more air, relative to both sounding more similar from a low output impedance amplifier.

that's awesome man, thank you for the knowledge

[H713]

Most stereo receivers (at least the older ones) didn't give much thought to the headphone output. Most just use the power amp output and a series resistor (which forms a voltage divider) with the headphone impedance. @Nimrodor already went over this, though I think that there's a typo in their voltage divider equation - voltage across the headphone should be V_in(Z_Headphone / Z_Out + Z_Headphone). 

 

That said, there's nothing really wrong with the power amplifier. Unless you're short on power (doubtful), there's no real reason to upgrade. THD+N is low enough to be more or less inaudible. Looking at the design, it probably won't be all that great at driving really low-impedance speaker loads, but most of the time that's not a huge issue.

 

I'd probably suggest getting a new headphone amp (no need to spend more than $100 for most people). There are probably some preamp or tape outputs on the Yamaha that you can drive the headphone amp from.

 

Linear power amps were a mature technology by the mid 1990s. If you compare the performance of most 1990s power amps to what's on the market today, the differences are quite small.

 

 

 

 

[Spuriae]

10 hours ago, H713 said:

I think that there's a typo in their voltage divider equation - voltage across the headphone should be V_in(Z_Headphone / Z_Out + Z_Headphone).

You're right, I messed up on the equation. V_headphone ∝ Z_headphone where Z_out >> Z_headphone.