[KAuss]

Just about everyone who treads here will wonder this and I'm also one...

However, I'm not new to audio so I can already expect a certian degree (at least by way of physics) of expectation....

How many times did you upgrade youre receiver from say a $300 unit to a $899 unit and found it to be 3x better? Or hell, are you really pulling words out of your ass to proctect and justify your spendings?

I mean if you listen to music during a regular busy day, you will not notice these nanodiscrepencies... Background noise is usually louder than THD levels in modern electronics...

Unless you got the perfect situation to listen to your music in, the AMPing part really wouldn't matter...

Take this to heart...

"An amp built to the highest of standards will do nothing but amplify the signal fed to it, and not alter the sound at all..."

The source will provide 50% of the sound, and the drivers will produce the other 50%... The only time an amp will make a difference is if the amp is lacking and becomming a bottle neck... I highly doubt improvements of significant value switching from a receiver headphone out to a mediocre dedicated amp... For those that do, you might not actually be getting a good amp because your signal is being altered...

 

[davebot]

NAD is a cool company. I've asked them technical questions in the past, and they were very helpful. So I emailed them, explained that I had just bought DT 880s, and wondered about the suitability of driving them from the headphone jack on my NAD 7175PE receiver. Specifically, I asked if they could confirm or deny the following two "common wisdoms":

1. It's claimed that speaker amps are optimized for loudspeaker systems
that require lots of current and have impedances on the order of 4
ohms--and that these aren't ideal for headphones with impedances of 250
ohms. Any truth to this?

2. It's claimed that the headphone jack will typically have a higher
noise floor as a consequence of the headphone output being a V-divided
feed, directly off the hot end of the power stage. True?

The careful reader may discern in my questions some of the plausible explanations given by others in this thread. I'll post a follow-up if I hear anything interesting from NAD. Cheers!

 

[john_jcb]

Quote:

Originally Posted by KAuss However, I'm not new to audio so I can already expect a certian degree (at least by way of physics) of expectation.... How many times did you upgrade youre receiver from say a $300 unit to a $899 unit and found it to be 3x better? Or hell, are you really pulling words out of your ass to proctect and justify your spendings?

I doubt that there are few that have been down an upgrade path that expect a 3X improvement for 3X the cost. In actuality as you get toward the high end it costs more and more to squeeze out the smallest of improvements.

 

[davebot]

I didn't get much, but I did get a reply from NAD. They say:

The headphone jack can drive these headphones as
the output impedance from the jack is increased from 4 0hms to about 300
ohms. So headphones from 8 ohms to 600 ohms can be driven easily without damaging the headphone coils. The sensitivity can vary but most
headphones have 90-110 db sensitivity anyways.

Hmmm. So is the headphone jack on my NAD receiver a 300-ohm feed, tapped from the main amp section's output?

 

[tbonner1]

Thank-you once again, Mkmelt for all your research regarding the fine Marantz units with the Sennheisers. I found a mint Marantz 2230(don't forget to replace the jumpers!) and it sounds lush and very musical with my Senn 650's, a real bargain at under $100. These phones need power and benefit from the big power supply of the old Marantz units that many headphone amps cannot duplicaite.

I agree that the Marantz does not sound best with low impedence headphones. Besides the Fisher 400 tube receiver, what type of vintage unit(amp or receiver)works well with Grados?

 

[terrible]

I am also caught up in this headphone amp dilema, and because it's impossible to try before I buy must rely solely on the knowledge and wisdom of you more experienced guys......senior guinea pigs so to speak.
My current Sony str-db940 receiver may or may not do my 650's justice but I have an old Luxman receiver model R1050 from the 70's (just collecting dust at present) which I read somewhere sounded great with the higher end Senns. What do you think?
My 650's arrive tomorrow and I hope I'm not disappointed with them after all the hype about them. I do want to do them justice ,but if I can get away without the purchase of a dedicated amp that would be a big bonus for my poor wallet.

 

[amb]

Without a schematic diagram to the NAD receiver, and not having opened it to look at its innards, I can't be certain, but I'm almost sure that the headphone jack signal is probably tapped off the main power amp's output, using a series resistor for each channel (probably in the order of a couple hundred ohms or more).

This scheme is commonly used for a couple of reasons:
1. Low cost - a couple of resistors and a jack is cheaper than a dedicated internal amp for headphones. The resistor also serves as protection for the headphones against burnout.
2. The resistor serves as a level "normalizer", making the headphone jack suitable for use with a broad range of headphones (both lo-Z and hi-Z). This is because the resistor and the impedance of the phone forms a voltage divider, and you get a greater attentuation with lo-Z phones than you would with hi-Z.

This scheme has some major problems, however. The resistor is linear across the audio frequency band, but the headphone impedance isn't (it's inductive due to the voice coil, and possibly also capacitive depending on design). What this means is that you do not get equal attentuation in the resistor/phone voltage divider across the audio band. Typically you would get a rising frequency response in the treble. Some people might even think "more is better", but it is certainly not accurate nor desirable.

Also, the resistor reduces the "damping factor", which is the ratio of the phone's load impedance to the amplifier's output impedance. The result is that the amp does not have as "tight" a control over the phone diaphram and contributes to loss of bass and lower midrange definition.

Using a quality, dedicated headphone amp with sufficient output drive capability, connected through the tape monitor loop of the receiver *should* in virtually all cases result in an improvement in sound.

-Ti

 

[tbonner1]

I used to own a Luxman 1050 which I beleive to be around 1979/1980 vintage.

It was not a bad unit and seemed to strive to a standard just a bit higher than the mass market units of the day. This is saying alot because this time period was what many people consider the apex(or perhaps a year or two past) the peak of the Sansui,Pioneer, Kenwood,Yamaha wars when the build quality was quite good. Luxman fell victim to this war and was bought out by Alpine and became a different company.

My guess is that the Luxman may be better than the Sony which is not one of the ES models. The Luxman may have output transistors rather than IC's on the Sony. It is the output transistors of that period which are part of the good sound on units such as the vintange lower powered Marantz receivers.

Look for the Luxman to have a richer, warmer sound with the Sennheisers. The Sony may sound a bit more sterile,cold and bright by direct comparison.

Above all, enjoy your choice of a superb headphone. Many people wander in a neurotic quandry and go through countless headphone and amp permutations never being really "happy".

I believe the Senn 650's compare to the best headphones at any price. I have read that in order to better the Marantz as a headphone amp you would have to spend 3-$400 which would put you in the range of a PPA headphone amp which many consider to be one of the very best amps. If your Luxman compares to the Marantz you should have a great combination. The only way I would know for sure is to compare a Marantz(which is a well known commodity in terms of sound quality) to the Luxman side by side. You may want to post a question on this forum and ask if anyone has tried both and get their unbiased opinion.

Good luck and let us know what you find just as friends like Mkmelt have helped all of us with his Marantz info.

 

[mkmelt]

"Also, the resistor reduces the "damping factor", which is the ratio of the phone's load impedance to the amplifier's output impedance. The result is that the amp does not have as "tight" a control over the phone diaphram and contributes to loss of bass and lower midrange definition."

I have only heard a loss of damping factor with one headphone - receiver combination. When I tried my HD-600 phones with a Fisher Futura Series 201 receiver, a well-made modestly powered solid state receiver made in Japan under the Fisher brand by Sanyo around 1971, the bass was muddy and poorly defined. Otherwise, the Future 201 was a nice receiver with a very sensitive tuner. I later gave it to a friend whose Technics receiver was on its last legs and it has been getting regular use in his basement office for more than two years driving a pair of AR 4X loudspeakers.

 

[rsaavedra]

The 3 year warranty of my Marantz SR-4000 AV receiver just expired earlier this month. I just opened it to to replace the stock cord. Took some pics in case someone here can provide any insights about the headphone jack connections/circuitry etc from the pictures. It is very tight near the headphone jack, so the pictures might show very little though, doubt they will help, but wanted to post them anyway.


Top view of the opened receiver. The headphone jack is in front of the transformer shield, to the left and about a quarter length of the receiver from the top of the picture:

 

[davebot]

Quote:

Originally Posted by amb This scheme has some major problems, however. The resistor is linear across the audio frequency band, but the headphone impedance isn't (it's inductive due to the voice coil, and possibly also capacitive depending on design). What this means is that you do not get equal attentuation in the resistor/phone voltage divider across the audio band. Typically you would get a rising frequency response in the treble. Some people might even think "more is better", but it is certainly not accurate nor desirable. Also, the resistor reduces the "damping factor", which is the ratio of the phone's load impedance to the amplifier's output impedance. The result is that the amp does not have as "tight" a control over the phone diaphram and contributes to loss of bass and lower midrange definition. Using a quality, dedicated headphone amp with sufficient output drive capability, connected through the tape monitor loop of the receiver *should* in virtually all cases result in an improvement in sound. -Ti

Thank you! Based on your information, I would expect a dedicated amp to give me more mids and bass, and punchier bass--improvements, I think. Even though this setup sounds pretty good, I do have the perception that my Audio Research / Vandersteen combo has more and better defined bass and mids than my NAD / DT 880, and I think the headphones now sound a little more boring. I would expect the DT 880 to sound better than my Vandersteen 1b speakers. . . but then again, the Audio Research outclasses the NAD's headphone jack.

 

[amb]

Quote:

Originally Posted by rsaavedra Took some pics in case someone here can provide any insights about the headphone jack connections/circuitry etc from the pictures. It is very tight near the headphone jack, so the pictures might show very little though, doubt they will help, but wanted to post them anyway.

Can't really tell from the pics. Sorry.

-Ti

 

[pbirkett]

Quote:

Originally Posted by davebot Thank you! Based on your information, I would expect a dedicated amp to give me more mids and bass, and punchier bass--improvements, I think. Even though this setup sounds pretty good, I do have the perception that my Audio Research / Vandersteen combo has more and better defined bass and mids than my NAD / DT 880, and I think the headphones now sound a little more boring. I would expect the DT 880 to sound better than my Vandersteen 1b speakers. . . but then again, the Audio Research outclasses the NAD's headphone jack.

Dont bet on it. I havent had a headphone amp yet that provides more bass than using headphones on my Rotel integrated amp, which does a tremendous job on some headphones to be fair. What you will get is a clearer sound, better definition and staging and better transparency.

 

[pd-pat]

It is nice to see this discussion as I am in the same situation with my new HD650. Till now I have connected my old Beyer DT770 to the speaker outputs of my Onkyo Receiver. I used a voltage divider optimised to high damping factor and a voltage ratio of 10:1. This means 10Ohm in serious to the headphone and 1 Ohm in parallel. The amplifier "sees" 11Ohm load which means it operates as if loudspeakers were connected (the 10 Ohm voltage divider resistor becomes pretty warm at high volumes). You could also say that with this circuit the amplifier has 10 Ohm output resistance.

With this set-up the volume potentiometer of the receiver is operated between 9-11 o'clock.
Compared to all headphone jacks of my components this made a noticeable advantage in all directions (bass impact, deepness, clear highs, more "room").
Till now I did not get a technical explanation why a headphone amp should sound better than a speaker amp with headphones if the speaker amp is connected via voltage divider with the headphone. Please notice that I talk of amplifiers which are principally comparable in sound quality.
But if we talk about a 200 Euro (or Dollar, it is nearly the same) receiver or speaker amp and of a 600 or more Euro headphone amp I am sure that the headphone amp can sound better because the parts are better in quality and in most cases class A circuits are used which is advantageous.
I am looking forward to my Hi-fi dealer getting the new Lehmann headphone amp. Then I can compare my CD-Player jack (comparably good, I can take it as my known reference) to a REGA Ear and the new Lehmann Linear (new German Class A headphone for around 650 Euro). If the above said is true then the Lehmann should make a remarkable improvement compared to the CD-Player jack and the REGA should be inbetween. I will let you know.

PS: This is a great forum here. In Germany we live in a real desert regarding headphones and amplifiers. It is great what is going on concerning this issue in GB and USA.

Regards, PD-Pat