Headphone outputs on hifi separates underpowered?

[stevehertz]

I read on another forum that "most headphone outputs are woefully underpowered". The context was hifi separates, so other than that I can't 100% specify any further. But it got me thinking. I have only very occasionally used headphones in over 45 years using a 'proper' hifi system, but I don't ever recall ever having a problem with distortion or sound degradation in any way. Is there something to this, or is it another hifi myth? I am of course aware of gross impedance mismatches that can sometimes occur, but that's different to "most headphone outputs being woefully underpowered". What's your view, knowledge, experience?

[mhennessy]

There are technicalities that can be discussed, and there will occasionally be situations where such a device might be useful, but the shortest answer is this: people make and sell headphone amplifiers. Hence, it's really important that consumers are made to understand that "most headphone outputs are woefully underpowered". Really important to people who make and sell headphone amplifiers, naturally

[mark2collection]

From past experience, using the output on say, a CD/MD player or indeed a cassette deck has produced, clean/undistorted audio, albeit, very quiet. My DAT recorder being a bit better in terms of gain.

I guess for comfort/longer listening this isn't such an issue, but in a busy/noisy environment with open-back headphones, could be a problem.

Generally using headphones on a pre-amp/integrated should produce fantastic results.

Slightly off topic perhaps, this reminds me when at college & I bought my first HiFi amp. Plugged headphones in, played a favorite track, wound the volume up to be greeted by my Father, standing in the doorway ... muttering something ... I stopped the music, slid headphones away ... 'sounds nice, doesn't it Mark?'

What I haven't told you, my old music centre 'muted' the speakers upon inserting the 1/4" jack plug, the HiFi amp had a separate switch, which I failed to notice!!!!

But no, not had any real issues & I've used all manner of headphones with all sorts of gear, generally, using the main amp is sufficient, just turn the volume down before re-engaging the speakers ... that's the fasted my sister has moved in years

Mark

[Ted Kendall]

Yes, most cans are fine on most headphone sockets, the odd exceptions being electrostatics, which generally have their own power units/adaptors anyway, or the venerable, and to my mind excellent, Wharfedale Isodynamics, which were best used straight across a speaker output and were supplied with a DIN speaker adaptor for the purpose.

[cmjones01]

I wouldn't say that headphone outputs are 'underpowered', but they often can't deliver enough voltage to drive anything other than 32-ohm Walkman-type headphones to reasonable volume. I use a pair of Beyerdynamic DT990 headphones which have 600 ohm drive units. They don't need a lot of power, but their high impedance means they do need quite a high voltage to make a decent noise. A lot of headphone outputs, especially on modern 3V-powered portable devices, are inadequate for this. I did build a headphone amplifier which could deliver +/-15V, and that worked fine.

Chris

[vidjoman]

Perhaps it’s the ‘protection’ applied to amplifiers to reduce the output to protect your ears from possible damage. Have you tried your phones on vintage amplifiers that could drive the them harder and cause premature deafness?

[turretslug]

Obviously, there will be exceptions to every rule, but separates headphone sockets will have been designed according to budget priorities, right at the top of the list will be "must run from signal circuit supplies- transformer and regulator costs have already been nailed down", along with "off-the-shelf signal op-amps- well, OK, use a low output impedance type, but don't spend more than an extra 0.5 cents/unit" and "no extra heatsinking- aluminium costs already spoken for". In short, might be paralleled 4558 on a good day. So, compared to the 2x 200 watt Krell belonging to the reviewer, they will indeed be "underpowered" but they will fulfill the brief of powering typical mainstream headphones (no electrostatics, no Stax, no '70s monsters with cans like pudding bowls and multiple low-impedance drivers). I view separates unit headphones sockets essentially as a check/ monitoring extra- LH is a bit low/trebly/distorted/whatever through the loudspeakers, is it the amp or the source?- that kind of thing.

[paulsherwin]

It's mostly a problem with portable gear. Hifi amps, CD players and cassette decks produce perfectly decent output levels unless your headphones are something exotic. My Sony MDR-V7s have been fine with everything, and sometimes too loud when there isn't a volume control.

[MrBungle]

Even the direct output on the Technics SL-PG490 CD player is enough to drive a pair of HD25 cans. Not sure what the fuss is about. Sounds like someone is trying to sell a magic box.

[bikerhifinut]

Never had a problem with headphone outputs on Integrated Amplifiers.


Cassette decks and CD players, the only ones i had were a bit weedy apart from an old Sansui that had its own volume control, the rest were fixed level outputs and they were a bit underpowered. Never an issue as I wouldnt have had them out of the system.
I can see a use for a small separate headphone amp if I didn't have or need to listen through loudspeakers as I don't like the level limiting on modern portable devices. I guess we can't be trusted not to deafen ourselves or more likely its lawyers and insurance companies saving the manufacturer from lawsuits.

A.

[boxdoctor]

Technics HiFi seemed to have generously loud headphone outputs on most models.
They tended to stick to the attached circuit (one channel shewn) which uses the M5218 s.i.l. dual op-amp, in most HiFi and keyboard products at one time. Tony
Apologies for the strange colouration - only noticed it after posting....

[cmjones01]

Originally Posted by boxdoctor

Technics HiFi seemed to have generously loud headphone outputs on most models.
They tended to stick to the attached circuit (one channel shewn) which uses the M5218 s.i.l. dual op-amp, in most HiFi and keyboard products at one time.

That explains the good performance, then: the M5218 op-amp is fairly beefy, and the +/-15V supplies will allow it to deliver quite a lot of power into even high impedance phones, with the power into lower impedance ones being limited by the series resistor. A sensible design.

Chris

[jamesperrett]

Most older amplifiers would have driven the headphones from the speaker outputs via something like a 100 ohm resistor. This had the effect of attenuating the signal to low impedance headphones while allowing high impedance headphones to see close to the full voltage output. I don't recall ever having a problem with this sort of output.

Back in the old days when 8 ohm headphones were common I remember finding the output of my old Ferguson(made by JVC) cassette deck to be too loud but the solution was to buy a pair of headphones with volume controls on them.

[Cobaltblue]

Did loads of listening on headphones from the 60's to the 90's and appart from now being a bit deaf (what did you say) never had a problem.

I had a sony CD player that I used in the late 1990's in Gaungzhou with earphones and it was plenty loud enough. You have to play Nevermind loud But I did have to overide the loudness control.

I don't beleive headphones are underpowered something else is going on

Cheers

Mike T

[bikerhifinut]

Funnily I was checking out the specs of some headphones just now Mike, and their spec stated an SPL of 99.6 dB with 1mW in. That's enough to cause a permanent shift in ones hearing! So basically all you need is a few mW for a bit of headroom if my reasoning is sound? So why do you need a headphone amp that pushes out a watt or more as some claim to do. Unless its for those who use high impedance phones where i guess the power output would be attenuated a bit? even so.........................

A