Headphone amp

[RedPhil]

Hi, I'm thinking about getting a headphone amplifier but not sure what the benefits might be in my system, which is as follows:

Thorens td125 mk1, with jelco sa750d and at440mla cart; musical fidelity v-lps and arcam diva a75+ amplification. I use audio technica ath ad700 headphones.

At my budget I'd be looking at either the basic pro-ject headbox or the musical fidelity v-can to compliment the v-lps. Would either of these give any significant improvement over the headphone out on the arcam or should I be spending my £100 elsewhere?

Any opinions appreciated

Thanks Phil

[13oots2]

I doubt very much a headphone amp in that price range is going to make much difference. Depending on what sort of sound you like you may find the AT cans a bit tame compared with the Grado SR80i's. It all boils down to what your personal preferences are.

[RedPhil]

Thanks for the reply - your comment is appreciated. Anyone out there want to second 13oots2 or does anyone have another view.
On the choice of headphones I'd agree with your sentiment except for tame I'd say warm, spacious and open. I tried the grado 80is before going for the ad700. Although I'm not averse to a bit of bass most of my headphone listening is to jazz, soul and occasional classical music. So I went for the audio technica with this in mind.

Thanks again for your comment, phil

[Tako]

A headphone amplifier CAN be an improvement depending on several factors.
Most integrated amplifiers have a headphone output that is simply taken from the speaker outputs and padded down with resistors. As a result of this the output impedance can be pretty high, when using a low impedance set of cans you can get some pretty severe deviations in the frequency repsonse.
A lot of integrated amplifiers also develop a little bit of hum and/or hiss as they age, with speakers you'll probably only pick this up when you put your ear next to the tweeter, but with headphones it can quickly become annoying, particularly with low impedance, high sensitivity headphones.
Some headphone amplifiers also produce noise, the Musical fidelity tube models are known for this. (Not really an issue on any but the most sensitive cans)
Both the Pro-ject (I have the Head Box SE II in my bedroom) and the Musical Fidelity are op-amp based models , with low output impedance and great specs and are dead quiet.
The Pro-ject I own sounds great, and effortlessly powers the most demanding headphones (Hifiman HE-6), it is built quite well, exept for the cheap volume pot and lack of an on/off switch.

If you are using Sennheiser models for home use (HD600/650/800 etc)or high impedance Beyerdynamics there's probably very little reason to buy a headphone amplifier (Although I owned several integrated amplifiers that had audible hiss even with the HD800), but when using something like Denon AH-D2000/7000, Beyerdynamic's low impedance models or headphones designed for portable use, chances are a dedicated headphone amp could make a difference. I don't know the impedance of your Audio Technica but suspect it is somewhere around 50ohm, which is very low for your integrated's headphone output.

Finally there's a little practical advantage to me: My amplifier is about 3m from my seat, and having a headphone chord running right through my room, with other people/pets walking around is a bad idea: A 5m interconnect and a small table puts my Headphone amp right next to my seat, with the added benefit of having the volume control within reach.

[RedPhil]

Hi Tako and thanks for the detailed response. You've opened up a new world for me now - just been checking the impedance of the various options. The output impedance of the headphone socket on the arcam amp is 80 ohms, the impedance of the headphones is 32 ohms - not dissimilar to the denons you mentioned. The output impedance of the two headphone amps is 20 amps on the pro-ject and 5 on the musical fidelity. I read as well that output impedance should be 1/8 of the headphone impedance. Is this correct does it mean that the musical fidelity is my best option?

Must say for the cost of these units second hand I'm tempted to give it a go, I can always resell if there proves to be no benefit.

Any other views on the impedance matching thing, its all new to me.

Thanks again for the post Tako

[Tako]

I did not realise the Pro-ject has a 20ohm output impedance, I thought it was much lower.
In itself an impedance mismatch does not have to be a problem, but as I understand it, the more the headphone's impedance varies across the frequency range, the larger the deviations in frequency response will be in the event of a mismatch. So even a low impedance set of headphones could sound pretty neutral on a high impedance output.
There is also the very real possibility that the impedance mismatch can sound pleasing , giving just that extra bit of bass thump.
The "1/8th rule" is probably a good guidline, but I have seen other figures like 1/6th, I would not worry about it.
The headphone out on my current Marantz Integrated is probably also around 80ohms, yet sounds fine with a 32ohm Beyerdynamic. The Denons tend to get a little too bassy on the Marantz however. (They allready are on the bass-heavy side themselves) Maybe you can take your headphones to a dealer that has a low output impedance amplifier to compare with a high impedance integrated, that would be the easiest way to determine if a headphone amp really is a good "investment".

I'm very much tempted by the Musical Fidelity V-can v2 myself, for the money it's just a cool gadget, and it feels better then the pro-ject, particularly the volume pot. (Haven't heard it, but sound-wise I would not expect much difference, but then again, I am a bit of an audio sceptic, YMMV)

[JoeE SP9]

See below for a description of the Musical Fidelity. I use Grado phones and have found that many headphone amps don't match well the Grado's impedance.

Copied from The needle Doctor's site:
The V-CAN is a genuine state-of-the-art headphone amplifier. Most high quality headphones have impedance of around 30 Ohms. Almost all headphone amps have an output impedance between 50 and 100 Ohms. Because of their high output impedance they cannot drive headphones properly. Any sound they produce through the headphones is necessarily coloured, with distortion and non linear frequency response. The V-CAN is quite different. Its output impedance is 5 Ohms. This means it will drive any headphone available with ease. It will produce low distortion, ruler flat frequency response and complete linearity.

[aardvarkash10]

Like any amp, output impedance of the amp dictates how much drive is available to the speakers. A high output impedance amp will have difficulty driving low impedance speakers. The greater the differential between amp and speaker impedance, the better.

The effect of a high impedance amp driving low impedance speakers is a loss of the BIG sounds - the amp just cannot squirt enough current down the wires to drive the speaker, so bass especially drops and/or distorts as the waveforms clip at the top and bottom.

Upshot - if your headphones are 32ohm, you are going to need a good low impedance source to drive them, or a low expectation level.

[RedPhil]

Thanks for the replies, I'm leaning toward the musical fidelity v-can, but with what I've learnt here I've an open mind as to the results I might expect, if there is no improvement I'll sell on. Another consideration for me is that I use the v-lps so I'd assume an amount of compatability and if all goes well could also in the future upgrade with the v-psu for both units. Thanks again for your comments, all are appreciated. Phil