[Letitroll98]

Or more accurately, is the headphone out on classic receivers/integrateds as good as or better than some modern dedicated head amps.  There's a big thread over on head fi about this and the objectivists say that taking the speaker outs and putting a resistor in series to the headphone jack, what is done when you don't use op amps, will generate detrimental response errors.  This makes a great deal of sense.  Subjectivists say just listen, they sound fine and sometimes better than modest op amp based head amps made today.

I have a dedicated Audio gd DAC+ head amp and a NAD 3020B integrated amp.  While the Audio gd is more detailed, more accurate, the NAD is just more musical and less fatiguing.  I sympathize with the argument that it's not accurate, the highs are definitely rolled off, but it's so much more like the high end head amps I listened to in Canmania at Capfest last weekend.  Smooth and sweet.  What are you guys listening to?

[neobop]

I didn't read the thread at Head fi, but when it comes to vintage the objectivists don't know squat.  High quality vintage pieces have dedicated headphone amps.  I have an old Mitsubishi tuner/preamp with a headphone amp.  It works without a power amp.

I don't know about your NAD.  They tend to be very polite.  Maybe that's how it sounds? 
If you can separate the preamp from the amp, pull out the jumpers and see if you get anything out of the headphone jack.  If it doesn't have the jumpers let me know.  I have an old NAD integrated that I can test for you.  I know it has a headphone jack.  I don't use it.
neo

 

[Letitroll98]

Thanks neo, I have the jumpers so I'll give it a go tomorrow.  Yes, sweet and polite, but with balls, is the character of the headphone section and the preamp.  The amp run by itself as a power amp is direct and clear, a wonderful little powerhouse.  So I can confirm it's the preamp section that gives the 3020B it's soft and gentle reputation, the power amp section is a badass.  Hmmm, gives me an idea I may try later.....running the volume control of the Audio gd direct into the amp section of the NAD.  It works for speakers quite well, would it work for the headphone section?

Update from a site that will remain nameless, "To use a separate high power amplifier for your main stereo speakers while continuing to use the nad 3020'S inbuilt power amp for headphones...simply install Y adaptors to split the signal from the pre-amp out jacks."  This seems to indicate you need the power amp to run the headphone out, still, it will easy to confirm when I can dig around in my system tomorrow.

Second update I found a block diagram that shows the headphone out tapped off the speaker outs.  So pretty well confirmed, short of pulling the jumpers, that the headphone section is a resistor, I think 330 ohm, run off the main amp.

[adydula]

I have tried several vintage amps and their associated headphone amp sections and went as far as to find the schematics to see how they were/are implemented engineering wise as well.

Its so easy to get caught up in the nostalgia of older or vintage is nice, better or wonderful etc.

That said I found some of the AVR's headamp sections work verify well with many headphones.

I often scour the vinyl record shops to fins older hi-fi receivers etch.... from Pioneer 1000'series, NAD, Allied, Kenwood, Radio Shack, Sanyo. Marantz, etc.

After years if this my conclusion is there are good old head amps out there, but not really any better than lots of the modern stuff were have regardless of the never ending objective vs subjective  debates...

One pleasant surprise was the headamp section of a modern day pre-amp, AVA's Insight + pre-amp section....I often find myself listening to it over many other amps....

I have never tried to play cans via our normal loudspeaker power amps.... always worried I would damage my cans!!

On the flip side I just saw mgalush playing a set of 15" Altec Lansing with a small headphone amp!! (the new ODA amp by AGDR).

All the best
Alex

[neobop]

Thanks neo, I have the jumpers so I'll give it a go tomorrow.  Yes, sweet and polite, but with balls, is the character of the headphone section and the preamp.  The amp run by itself as a power amp is direct and clear, a wonderful little powerhouse.  So I can confirm it's the preamp section that gives the 3020B it's soft and gentle reputation, the power amp section is a badass.  Hmmm, gives me an idea I may try later.....running the volume control of the Audio gd direct into the amp section of the NAD.  It works for speakers quite well, would it work for the headphone section?

Update from a site that will remain nameless, "To use a separate high power amplifier for your main stereo speakers while continuing to use the nad 3020'S inbuilt power amp for headphones...simply install Y adaptors to split the signal from the pre-amp out jacks."  This seems to indicate you need the power amp to run the headphone out, still, it will easy to confirm when I can dig around in my system tomorrow.

Second update I found a block diagram that shows the headphone out tapped off the speaker outs.  So pretty well confirmed, short of pulling the jumpers, that the headphone section is a resistor, I think 330 ohm, run off the main amp.

I checked the NAD last night as I just happen to have it hooked up.  It's a 3050 integrated and the headphone jack didn't work with jumpers removed.
I had the speakers switched off, but that shouldn't make a difference.

The question then becomes one of a resistor on an amp output.  If it's implemented properly, and I assume NAD knew what they were doing back in the '80s, then I suspect minimal sonic consequences.  I also suspect the NAD would sound rolled off in comparison even if you weren't using the headphone section. 

Here's how to hook up a power amp for headphone use:
http://sound.westhost.com/project100.htm

You can see from the diagram this isn't a simple resistor in series with the output.  Even if you eliminate the switch to turn off the speakers there's a resistor to ground.  This is how a passive speaker attenuation network works (usually on tweeters).  You put a resistor in series with the driver and another across the driver terminals.  These are fixed values depending on the impedance of the driver and amount of attenuation.  It maintains flat response.

You can also hook up headphones directly to the output of an amp.  You just have to be careful.  It's not recommended for a high power amp.  You also can't do it with a bridged amp or one that cautions against using a common ground.  But it's okay with most all conventional power amps.  You can get a headphone jack and just hook up an extra ground wire.

You asked what people are using - I have a cheap DAC/HP amp, the Mitsubishi, and a Fiio E11.  The Fiio has a 3 position bass switch and if you don't need additional EQ, sounds good.  It has enough power to drive the T50RP.
neo

[Letitroll98]

Thanks guys.  Same results as you when I tried it today, no sound with the power amp disconnected, so at least one integrated uses the power amp to drive the headphone section.  As an aside I then disconnected the preamp and the wow factor returned.  The NAD power amp is dynamic, clear, and up front.  Not at all syrup and sweetness like the preamp section, it's like having a whole nother headphone amp.

So with the little personal detour over, back to is anyone else using receivers or integrateds as head amps.

[gjclaxton@gmail.com]

I only use speaker amps with my he-6, do not even own a headphone amp.  Had a v200 but it could not compete with using a speaker amp.  I connect an adapter to the speaker outs of a blue circle power amp.  Sound is wonderful. My adapter has resistors that can be bypassed and have none engaged usually, but the he-6 is pretty inefficient so it is easier to get away with.  I also have some tube amps where I engage parallel resistors in the adapter so that amps are under load (this protects the amp).    You might want to read the headfi thread even though it is long. 

[Letitroll98]

Thanks for the info, which begs the question, if the headphone section in a vintage integrated is a resistor network taped off of the speaker outs, what's different in using the speaker lugs with a resistor network?  Other than that's how you implement it using a power amp.  Am I right in assuming we are doing the same thing?

[gjclaxton@gmail.com]

I think they can be pretty much the same thing.  In my case there are more cables unless you get your headphone cabled to connect to speaker outputs.  I do find that when I engage the series resistors, in addition to getting attenuation, the music feels a little less intimate -- moving a few rows back so to speak.  Not necessarily a bad thing.  With the receiver, it of course depends on how much attention they put into the headphone out. You pretty much are limited by what the designer did.  And of course if you work from speaker outputs you can use any amp you have whether or not it has a headphone out (none of my do). 

[Letitroll98]

I think I may have the best of both worlds.  I have an Audio gd DAC/headphone amp combo with a volume control.  That runs to a NAD 3020B which has pre outs and power in jacks, I'm running from the DAC to the power in jacks bypassing the pre, but because of the design, still gives me a headphone jack.  The result is more dynamic and detailed than any head amp I've yet listened to, albeit I've heard head amps that are prettier sounding.  Which is the other side of my world, I can put the NAD pre back in the loop for sweet and syrupy smooth whenever I feel like it, maybe today.  So I have two amps in one, both with their strengths, for essentially free as I've had the NAD for thirty years now.  I'm really glad I've carted that baby around all this time.

Maybe someday I'll try a resistor network on one of my power amps, but for now I'm more than content.

[terry parr]

my experience with modern, dedicated h/p amps is limited, so i can't make an informed comment to the original question that Letitroll asked to start with, but on the subject of using the headphone out on an older integrated or receiver let me mention something that nobody has commented on so far (and something that appeals to me). 

quite a few of the older amps and receivers have both tone controls and a "loudness" feature (where, when engaged, gives a boost to low frequencies at low-volume listening levels).  both of these features are defeatable in both of my (older) amps.

with most of the modern, dedicated h/p amps, you're stuck with the source material "as is", arn't you?  (with no way to make any adjustments to the sound of the music that tone controls or a "loudness" feature would allow you to do).   



 
     

     

[fmw]

Or more accurately, is the headphone out on classic receivers/integrateds as good as or better than some modern dedicated head amps.  There's a big thread over on head fi about this and the objectivists say that taking the speaker outs and putting a resistor in series to the headphone jack, what is done when you don't use op amps, will generate detrimental response errors.  This makes a great deal of sense.  Subjectivists say just listen, they sound fine and sometimes better than modest op amp based head amps made today.

I have a dedicated Audio gd DAC+ head amp and a NAD 3020B integrated amp.  While the Audio gd is more detailed, more accurate, the NAD is just more musical and less fatiguing.  I sympathize with the argument that it's not accurate, the highs are definitely rolled off, but it's so much more like the high end head amps I listened to in Canmania at Capfest last weekend.  Smooth and sweet.  What are you guys listening to?

There is no particular reason to think that a headphone amp built into another audio component should perform any differently than one in its own box.  There is nothing complicated about headphone amps.  Possible?  Sure.  But making a broad statement like vintage headphone amps sound better than modern ones would be a statement I would ignore completely.

[dB Cooper]

fmw, the "catch" is that almost no receivers/integrated amps (especially vintage ones like we are discussing) have actual separate "headphone amps" built in. They simply tap off the output of the power amp section through resistors (which keep you from blowing up your cans which can only handle a fraction of the power of speakers).

The problem with this is that it causes the headphones to "see" a high output impedance which causes frequency response problems, distortion increases, and phase non-linearities. this article by the Jack Kerouac of audio, Nwavguy, explains the problem well. So does This paper published by Benchmark (pdf download link)is a good read too but more technically challenging.

In a nutshell, the problems relate to the relationship between the impedance of the headphones and the output impedance of the source. In other words, damping factor. These issues are less severe with, say, 600 ohm Beyers (or my 2KOhm Senn 414's from yesteryear) than, say, 32 ohm Grados (examples chosen at random).

[neobop]

Well, yes and no.  Some vintage receivers do have dedicated headphone amps, as well as virtually all preamps with headphone jacks.  There was one preamp that had connections to hook the phones to the amp, but that was the exception.  These receivers were usually from the '70s, but I believe the top Pioneers for example, had headphone amps after that. 

Even if you have an old receiver that runs phones off the amp section, you have to try it to find out, YMMV.  Results depend on what phones and receiver you have, and your taste.  So throw the rule book away.  What sounds best rules. 
Buying a $20 Fiio for comparison is a good idea.  Even if it's not enough power for a particular set, it should tell you about balance differences, top to bottom.

Transistor amps have very low output impedance.  Do people hook up phones directly to the output of these low power amps they sell today?

Check out the last post on this thread:
http://www.head-fi.org/t/589415/does-a-vintage-receiver-cut-it-as-a-headphone-amplifier/15

neo