Why does it sound different?

[Vintagefan]

Simple answer: if we (amir) would measure output at a low impedance ( >100 ohm or even 50) we would have no problems, but this is not the fact! So driving low input impednce input, certainly at high voltages will put the output stages under stress… lac of power (current) makes the difference. Same with damping factor of amps, verrrrry significant for sub-bass! Needs lots of copperwinds to cope with back- emf.

 

[A Surfer]

So at what point, and at which conditions does say dampening factor create audible differences? And if it is audible, it will be measureable so I am curious what evidence base makes you present as so certain about this?

 

[staticV3]

Simple answer: if we (amir) would measure output at a low impedance ( >100 ohm or even 50) we would have no problems, but this is not the fact!

Please be more specific.

Amir measures DACs at 600/100k/200kΩ

Headphone Amps at 12/16/20/32/50/300/600/100k/200kΩ

Power Amps at 2/4/8Ω

 

[Vintagefan]

600 ohm is a whimp, 50 ohm at 6v please. Otherwise pro xlr is NOT.
one of the reasons 5532 is still in existance.

 

[DVDdoug]

600 ohm is a whimp, 50 ohm at 6v please.

What are you talking about? We need some context... Line inputs are typically 10K-100K so testing at 600 Ohms is usually farther down than you need to go...

Headphones are usually 32-Ohms or more.

I think I've seen IEMs that are 16-Ohms.

Of course most speakers are 4 or 8-Ohms but some car speakers are 1 or 2 Ohms.

Note that the published spec for an amplifier (or other electronics) is usually the recommended minimum load, not the effective source impedance which is lower.

On a receiver, the headphone output sometimes goes-through a resistor (for voltage reduction) and since headphone impedance varies over the frequency range, that can result in frequency response variations.

Or some headphone outputs have DC blocking output capacitors. That makes a high-pass filter (DC is zero-Hz) and depending on the capacitor value the cutoff frequency can go-up into the audio range with low impedance headphones, reducing the bass.

Most solid state power amplifiers have a low-enough damping factor that it's not a problem. And if they have output capacitors, they are designed for 4 or 8 Ohms so that's not a problem either.

 

[Vintagefan]

Used to commercial, not pro standards!
ok, crest 8001 is old-fashioned welding machine.
bose made wonderfull amps with extemely high current to drive extremely poor sounding loudspeakers. On good speakers they are superb.

 

[BDWoody]

600 ohm is a whimp, 50 ohm at 6v please. Otherwise pro xlr is NOT.
one of the reasons 5532 is still in existance.

What are you driving with a DAC that has 50 Ohm input?

 

[terryforsythe]

So at what point, and at which conditions does say dampening factor create audible differences? And if it is audible, it will be measureable so I am curious what evidence base makes you present as so certain about this?

This article delves into some explanation: https://sound-au.com/biamp-vs-passive.htm

Wikipedia also has an article, but it does not go into enough depth to cover the scenario when passive crossover components are used: https://en.wikipedia.org/wiki/Damping_factor

I'll throw out my subjective experience. I removed the passive crossovers from my speakers and went all active. Doing so increased my system's damping factor by 8x - 10x. This significantly improved the bass response of my woofers - tighter, more natural sounding.

 

[staticV3]

600 ohm is a whimp, 50 ohm at 6v please. Otherwise pro xlr is NOT.

Nonsense.

If you're driving a 50Ω load directly from your DAC, then that's just user error.

 

[somebodyelse]

600 ohm is a whimp, 50 ohm at 6v please. Otherwise pro xlr is NOT.
one of the reasons 5532 is still in existance.

At times like these I wish the opamp load sensitivity measurements were still up at www.douglas-self.com - the distortion of the 5532 increases significantly as the load decreases. IIRC the recommendation was not to use them into less than ~1k2, or to use multiples in parallel. You would need quite a lot to maintain performance down to 50R though.

 

[Vintagefan]

Do I have to explain why abondant constant current, not peak current, is essential?
Linear PSU‘s with large capacitance sound better!
Take a look at the basics on Pass’ diyaudio website into the very first basic schematics and distortion figures.
Also, it’s input/output impedance, not always pure resistive.

 

[BDWoody]

Do I have to explain why abondant constant current, not peak current, is essential?
Linear PSU‘s with large capacitance sound better!
Take a look at the basics on Pass’ diyaudio website into the very first basic schematics and distortion figures.
Also, it’s input/output impedance, not always pure resistive.

I don't think this thread is destined to be very productive.

I'll just call it here.