Headphone amp vs Stereo amp: My thoughts and advice (LONG)

rozzar said:
the ones you linked to are the Signatures @ £1000 or so!! i just had the boggo £400 ones. In comparison to the £2500 Celestion Kingstons I had at the time, i only marginally preferred the Stax's as they had a slightly better bass extension. For serious headphone users (n.b. who like a REALISTIC portrayal of music, as opposed to what THEY want to hear) then imo there is no better headphone, and the issue of headphone amps is taken out of the equation- Stax's have their own energizers, which can be upgraded through the different (5 iirc) tiers. www.signals.uk.com stocks them :)

LOL...yes,I wondered,but wasnt sure!

As to serious users!...I do agree that they're excellent cans,and the amp issue notwithstanding(not exactly removed,merely changed,and using another amp as the signal source for the energiser),both these,and dynamic cans with an amp have their advantages and disadvantages,along with those who reckon that one is better than the other.
As with everything else,it is subjective,and I personally like a good dynamic setup overall,but like you,find it interesting how much you have to spend to better them with speakers.

A friend of mine has just forked out for a set of Novas and seems very happy with them also,but I do think that a really good set of cans,fed a good signal,irrespective of dynamic Vs electrostatic,can better speakers costing many times as much.

BTW...nice piece of Antipodean amplification you have there!
 
I have an Arcam Alpha10 amp fed by a Arcam CD72 CD player. I have Grado RS2 phones (impedence 32 ohms). I recently bought the Slee Solo amp (latest incarnation).

I found the difference in sound quality very noticeable from the Slee. Particularly the upper and midrange. Much more clarity and detail. I could hear things that I could not via the Alpha10.

I paid £400 for the headphone amp and would do so again.

Martin
 
Jonesthegas wrote:
I found the difference in sound quality very noticeable from the Slee. Particularly the upper and midrange. Much more clarity and detail. I could hear things that I could not via the Alpha10.

John Dawson wrote:
I am prepared to bet that driving this from the speaker outputs of an A85 or other Arcam integrated amplifier would give sound every bit as good as dedicated headphone amplifiers at a tiny fraction of the cost (all the bits from Maplins would probably cost a tenner or less).

I am still more than happy to put John's theory to the test if someone would be prepared to give me some guidence. As I have stated earlier, my amps are Arcam Alpha 7 int. and 8p power, my cans are Senn. 590 with 120 Ohm impedence. (That is if John thought that at 120 Ohms there would be a worthwhile difference over the headphone jack ??)

Cheers

Croc
 
Well I'll press on dispite my apparent invisibility around here :) and hope that someone can give me some feed back on this.

Below is a link to a schematic that I've adapted from another attenuator design. I've removed switching because my amp already has A/B speaker switching and I've show both channels as the original was only for one channel. I've made the earth common to the jack end(I assume that is how jacks are wired) and I guess the other end goes to the -ive (black) speaker terminals?
attachment.php
Now if I were anything like on the right track I'd need the correct resistor values. Here is a table table from the original design showing suggested values for given amp ratings:

Power-8Ω-------R1--------R3--------Zout-------Vout-------R1 Power
--20 W--------180Ω-------47Ω------119Ω-------5.2-------0.33 - 0.5W
--30 W--------270Ω-------47Ω------122Ω-------4.9-------0.47 - 0.5W
--40 W--------330Ω-------33Ω------121Ω-------4.8-------0.54 - 1W
--65 W--------470Ω-------22Ω------118Ω-------4.7-------0.74 - 1W
--100 W-------560Ω-------22Ω------121Ω-------4.9-------0.95 - 1W
--150 W-------680Ω-------18Ω------120Ω-------5.7-------1.37 - 2W
--250 W-------1kΩ--------12Ω------119Ω-------5.1-------1.79 - 2W
Resistor Values for Different Power Amplifiers


Now my headphones are Senn. 590 which are 120 ohm and 97dB sensitivity
My amps are either Arcam Alpha 7 which is 40w or Alpha 8p which is 50w. So I assume that I'd be looking at the figure either for the 40w or 65w amps. It appears that these figures would run the jack at around 5v, just a little over what John Dawson was recommending I think.

Finally, if I am on the right track (I'm quite prepared to believe I'm not :clown:), suppose I were to make an attenuator, would it drive my cans any better than the jacks (both amps have one) provided given That John Dawson stated that jacks on Arcam amps are around 77ohms

Well I hope this one draws a response, Alex you must have some insight into all this, and maybe we could get John back to offer his valuable opinion, even if it were "stop talking nonsense and go away and learn electronics" :D and surely Paul you must know what I need at the jack to optimise cans at 120 ohm

Cheers

Croc
 
Good grief you have been busy! I am away a lot and have a business to help run which is why I can't get too involved but here goes....

Firstly in an ideal world one would drive the headphones from a zero source impedance, in the way loudspeakers are when connected directly to the outputs of an amplifier. In practice the amplifier's main outputs are far too great for headphones, so an L attenuator is used. In your diagram these would be R1 in series and R2 to ground. R3 would be zero, i.e. a short circuit.

In most Arcam amplifiers, including your Alpha 7 and 8P, the value of R1 is 330 ohms and R2 is 100 ohms. If you wish to lower the output impedance without doing anything too complex, connect another resistor across R2. This will lower the peak output level available but may improve sound quality if the headphones do not like a highish source impedance (I suspect the Grados in particular may fall into this category). If you don't want to open the amplifier, which for safety reasons you shouldn't unless you know exactly what you are doing, then you could try unscrewing the phones' jack plug, if it is not a moulded type, and hook the relevant resistors (one for each channel) across the jack plug's internal connectors - the sleeve is common. Good values to try would be 100 ohms (thus lowering the output impedance of each channel to 43 ohms) and 47 ohms (making the output impedance 29 ohms). Eighth or quarter watt parts are fine. You would still get almost 2 Volts rms before clipping from your 8P with the 47 ohm resistors and your 120 ohm headphones - which equates to about 25 mW in the phones or about 110 dB peak level - pretty loud!

You would obviously need to equalise the "before and after" volume levels using the amplifier's volume control before doing any listening tests to see what improvements were gained by doing this.

HTH.

John Dawson (Arcam)
 
Hi John, if you are willing to put together a cheap headphone amp made of £20 maplin parts, I'll be willing to test it for you :smashin:
 

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