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

Discussion in 'Headphones, Earphones & Portable Music' started by WhyAyeMan, Oct 19, 2004.

  1. WhyAyeMan

    WhyAyeMan
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    As you guys all know, I have had my fair share of headphone amplifiers (and headphones), and there is one thing that repeatedly seems to come back to haunt me.

    It is my opinion that if you own an amplifier like mine (which has a built in headphone socket), and a similarly specced source component to what I use, I think that cheap headphone amps are a waste of money, and even the more expensive ones, which will undoubtedly be better than the headphone socket of a Rotel amp, are probably well down the road of diminishing returns anyway.

    OK, for some people, a headphone amp is essential, since their kit may not include a headphone socket (amp), or it might, but may well be underpowered (CD player), and for those people, a headphone amp, for headphone listening, will be essential.

    However, if like me, you have an amplifier with a pretty good headphone output, with certain headphones there is virtually no point whatsoever in a headphone amp. However, with others there may be more of a need.

    This is what I have found:-

    1. Lower impedance headphones tend to seem to take more advantage of headphone amps than higher impedance ones. The reason for this is to do with the output impedance of the headphone jack. The output impedance on a typical headphone amp will be close to 0 ohms. When you plug in a set of headphones, the impedance of the headphones contributes to the overall impedance in the "chain". So, for example, its clear to see that 0+32 ohm's = 32 ohms is probably a good thing for most headphones. However, take an integrated amp, which due to the resistor based design, has an output impedance of 220 ohms at the jack, this will more severely affect the sound. However, if you plug 250 or 300 (or even 600) ohm headphones into the jack, although they are still affected, it seems to affect them far less. Without being an expert in electronics, this has universally seemed to be the case in my experience. For example, the headphones that sounded distinctly disadvantaged on my Rotel were the Sony MDR-CD3000, CD1700, AKG K240 and K271 Studio headphones. All of these headphones are 55 ohms or less. Pretty much all of the other headphones were at least 250 ohms, and there seemed to be much less difference between the integrated and a headphone amp in these cases.

    2. Having said all that in point 1, it does not always follow that a low impedance headphone will sound bad out of an integrated. I firmly believe that some headphones were designed to be used in such a scenario. Whether that be by design or by the headphones sonic signature, some such headphones will sound better driven by an integrated amp regardless. Examples of headphones I believe were specifically designed for use with integrated amps are Beyerdynamics, the DT831, DT931, DT660 and DT860. All of these headphones are designed to be driven by the INDUSTRY STANDARD output impedance of 120 ohms, and not 0 ohms as most headphones seem to be.

    3. Going back to a bit in point 2, the headphones tonality can often dictate whether it'll sound any good on an integrated amplifier or not. Again this may or may not be by design. I personally find that the best headphones to use on integrated amps are definitely on the brighter side of neutral, and not too bassy. This is because when you raise the resistance of the output jack, it tends to have the effect of "warming" the sound, and increasing the perceived power of the bass, and decreasing brightness. With all this in mind, I'd say you wont go far wrong if you choose a headphone that has a highish impedance and a bright sound with not too exagerrated bass as standard for use with an integrated amp. Although you should audition because as I say it doesnt always follow for a low imp. can to sound bad on an integrated, the DT660 and DT860 are good examples of this. Grado also tends to sound quite good in this context. However, I WOULD SERIOUSLY avoid the temptation to go with warm headphones with an integrated amp, as the result tends not to be too involving (read dull).

    So, whether one considers a headphone amp should be dictated firstly by whether you have a jack to use already. If not, then obviously there is little choice. However, if one does have an amp with a headphone jack, I'd seriously question the need for one. I think the source is clearly the most important factor here, unless you have an output jack that sounds like total arse. If you have a jack to use, and you dont wish to spend too much cash, then consider a headphone suitable for use in such circumstances. I'd say the performance split was about 60% headphone, 30% source and 10% amp.

    Naturally if you want every last drop of performance, and money is no object, then by all means go for an amp, as the best amps will undeniably make some difference, but folks, dont go buying a headphone amp if you already have a good quality jack and expect a huge improvement, because you simply wont get one. My advice to you would be to get down a shop, and audition a number of budget amps like the Creek, Rega, X-Can. If you feel they make a big difference, then be confident in your purchase. However, try not to kid yourself, see it objectively, and if you dont feel there is a big improvement, dont bother. I have found out the hard way, but I will be glad if this thread at least makes people consider carefully their purchase, before doing what I did and wasting good money.

    Now, a few words about the Rega Ear vs my Rotel RA-01. The Rega seems to be *slightly* cleaner sounding, but really there is very little in it to all intents and purposes. The Rega is probably a tad more detailed, and definitely brighter. The Rega has a fairly leanish, but fast bass. The Rotel seems to have a lot more slam in the bass, and certainly is no less fun. Actually, a word on headphone bass. Tight bass in headphones IMO can make it sound a touch too clinical, and a bit of overhang gives a slightly more "speaker" like presentation, IMO. Also, the Rotel is a bit warmer, so although it gives slightly less detail, its ultimately a touch less fatiguing.

    On that note, I feel like I do not enjoy my music any less using the Rotel amplifier than the Rega. I am not saying that the Rega (or indeed my old Corda HA-1, Perreaux SXH1, X-Can v3 etc) were bad amps, just that as a bang for buck hifi component, they rate as one of the worst VFM "upgrades" for me, which have only ever really sounded different rather than better.

    HTHs someone.
     
  2. Daneel

    Daneel
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    Thanks for your thoughts

    I found my Senheiser HD580s to be vastly superior to my system when I had my 602s3s and just the Pioneer. With the power amp and the Electras things are much closer.

    You need to spend a hell of a lot to approach the quality of good headphones with speakers. Unfortunately for me, I don't like wearing the things nor do I like the soundstage they create. I only use them when I have to and when I want to listen very closely to something despite the fact that the sound itself is very pleasing.
     
  3. arcamalpha

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    You get everywhere mr Birkett :D
    Bill here off the hi-fi choice forum paul.
    I have a pair of grado sr60's, I tried the headphone socket on my arcam a85 amp, and to be honest was not very impressed with the sound, or to be ultra honest the lack of any oomph, whether this was symptomatic of the headphones I wasn't sure.
    So I spent £150 on a project headbox, ok it isnt going to set the world alight in the headphone amplifier field, but it was certainly a forward step from the headphone output from my £800 intergrated amplifier.
    Just seems sad that you can pay mega bucks on an intergrated amp and be disappointed with the headphone output of the said amp.
     
  4. WhyAyeMan

    WhyAyeMan
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    Daneel - I agree mate, headphones are ultimately a compromise from the outset, and no matter how much you spend on a headphone rig, it will never sound as good as even a fairly modest speaker rig IMO. That being said, I DO enjoy headphones, and I think my music is really good to listen to on headphones (trance), but if I was listening to some other genres, I might feel differently.

    Hi Bill - what are you known as on Hifi Choice? Anyway, I dont like to comment on things I havent heard, but for what its worth, I have heard a fair few folks criticise the headphone output on Arcam amps, so perhaps those amps do have a fairly lousy output. I agree though, it would be nice to have a decent quality headphone output on such an expensive amp. I have heard the headphone outputs on a NAD C350, my Rotel RA-01 and my mates Pioneer A400, all budget amplifiers, and they all made the headphones I heard on them sound pretty much as good as I'd heard them on budget headphone amps. Its a case of try it and see I'm afraid, and outside the likes of NAD and Rotel, its a bit of a lottery unfortunately.
     
  5. arcamalpha

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    Hiya paul, I'm known as Wanfield on the hifi choice forums.

    Found your post interesting paul, as always very clued up on things headphone/headphone amps.
    Good to see you on here paul :)
     
  6. Daneel

    Daneel
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    Actually, I was saying it the other way around, i.e. £100 headphones (HD580) are going to take a lot of beating, in my case £2k floor standers (Electra 926) are required to match them for sound quality.
     
  7. alexs2

    alexs2
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    Well...that is a big one!

    My 5p's worth....I'd definitely agree that cheap headphones,and cheap amps really don't do much justice to it,and the quality of a lot of headphone sockets on integrated amps/receivers are very poor indeed.

    If you have a good one,then you get to enjoy the benefits of a decent set of 'phones without the additional outlay on a dedicated amp.
    For my money,though,I agree with some of the other posts in saying that the levels of detail and quality offered by a good set of phones and a moderately expensive amp can elevate the sound quality to that of a speaker based system costing many times as much....obviously the bass grunt and imaging are gone,but there are still some things which sound better on my Sennheiser 600/Earmax combo,than either a Krell KMA/B&W Nautilus or Quad II/Quad ESL speaker systems.

    In the end,everything compared to live music(even that sometimes!)is a compromise,right up to the level of things like Wilson System 7's and Krell FPB's or Stax electrostatics....just a matter of what works best for you and your music.
     
  8. John Dawson

    John Dawson
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    Each channel of the headphones output socket on the A85 is fed via a simple resistive potential divider from the output of the main power amplifiers - 330 ohms in series and 100 ohms to ground. This socket therefore has an output impedance of around 77 ohms. These values were chosen as a compromise that will work with all headphones from those with very low (say 4 ohm) impedances right up to 600 ohms ones or more, as one cannot tell in advance what will be used and we want all types to work OK and not inadvertently deafen the listener. The chosen values also ensure that the series resistors can be of a reasonable physical size as they have to dissipate heat when the amplifier is running hard.

    The sound quality of the A85 is outstanding (and certainly not lousy!) with very low distortion and the amplifier's headphones feed is derived directly from the main speaker outputs. However I am prepared to accept that some headphones will work optimally when fed from a very low impedance source - in that case why not build a simple external attenuator to drive a pair of headphones, and switch it on and off with one of the front panel speaker switches? Its difficult to suggest optimum component values without knowledge of the particular headphones and some experimentation, but a series resistor of say 47 ohms (rated at 20W or so) and a resistor to ground of say 6.8 ohms (rated at 2W) would be a good starting point. It could all be built into a small die cast box. The maximum voltage swing available would be about 4 volts rms with an A85.

    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).

    So who wants to try this out and report back to the group?

    John Dawson (Arcam)
     
  9. alexs2

    alexs2
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    Interesting idea....I got as far as making up a box to take the speaker outs from a pair of Quad II's but haven't completed it yet(still have a little bit of soldering left),and it would certainly be an interesting comparison,although I'm not sure how an A85 or similar will stack up against something like an Earmax,even given the likely and obvious differences in sound quality of a transistor amp Vs an OTL/SET based headphone amp.

    If anyone wants to loan me an A85,I'd be happy to try for you!
     
  10. WhyAyeMan

    WhyAyeMan
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    A similar concept to this perhaps?

    [​IMG]

    Anyway, I'd love to try it, however, I have two problems:-

    1. I dont have an Arcam amp of any description (I have a Rotel RA-01)
    2. You couldnt meet anyone who does DIY more badly than I....

    Nevertheless, I would be happy enough for someone to tell me the details and build one for me - I agree with John Dawson, I see no reason why this kind of setup should be any worse than a headphone amp since the MAIN problem with most headphone outputs is high output impedance. Actually, the Arcam has quite a low output impedance at the jack anyway, so I would have thought it'd sound alright. I have tried many times to get Rotel to tell me what the output impedance of its jack is, but they never answer me.
     
  11. alexs2

    alexs2
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    Likewise....no Arcams here,and apart from my old 15W Quads(which Quad advised would probably be OK running unattenuated into 300ohm Sennheisers),I dont really fancy putting anything like headphones on the end of the Krells...certainly not with my head in the middle :eek:
     
  12. Crocodile JD

    Crocodile JD
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    I have 2 Arcam amps, an alpha 7 integrated and and alpha 8p power amp, I use them in a bi-amped config. I would love to try Johns suggestion however, I am electronically challenged so simple as it might be, I'd need a schematic to follow. John any chance of a sketch or something, the more layman the better. I do have soldering iron and basic electronics DIY kit though.

    Also, as an aside John, since both amps have headphone outputs I was curious to know which would give the best performance when connecting headphones conventionally.

    TIA

    Croc

    Edit: P.S. or If Paul's sketch is the very thing you mean, sad as it is, I would need slightly more explanation evan than that :blush: :lease:
     
  13. arcamalpha

    arcamalpha
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    The thing I found with my A85 was even at around 30 on the volume display, with my grado's attached, it wasn't doing a lot for me, not even making me deaf!

    Introduced the project headbox, and it was day and night.
    I do not argue that the A85 is a good amp, but I think its horses for courses when it comes to using cans.
    By the way, the headphone socket comment I make is just not a swipe at arcam, I have heard that other manufacturers have the same issue.
    I am not one for diy, but if anyone could make one of these boxes to be fed from the speaker outputs, they would have my order :clap:
     
  14. arcamalpha

    arcamalpha
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    John you will be sorry you posted here, I promise :hiya:

    Question for you sir, when I connect my cd82 to my project headbox, bearing in mind I also use the second cd phono output to my a85, the sound coming through my grado cans is how can I explain, muddled? like there is some kind of interference going on.
    However, when I power up my a85, the interference as I layman call it, clears up, and the sound is ok.
    Any ideas what can be causing this? it has got to the point where I just use my marantz cd6000 ki sig through the project headbox for my headphone sessions, but would dearly like to use my cd 82 without having to leave the a85 powered up.
    Many thanks John.
     
  15. WhyAyeMan

    WhyAyeMan
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    Dont worry, I dont understand it either ;)
     
  16. John Dawson

    John Dawson
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    Arcamalpha

    The A85 has protection diodes across all its inputs which are connected directly to the positive and negative 15V pre amp power rails. When the amplifier is powered on these will conduct only if the input voltage hits +/- 15.6V - it is to protect the circuitry inside against static damage. However when the amp is turned off the power rails are at more or less 0V so signals in excess of +/- 0.6V peak (0.4Vrms) will be clipped. Since the two outputs of your CD player are in parallel and deliver up to 2Vrms then in this situation you will get distortion as the amplifier's protection diodes load the CD player at peak signal levels. This is what you heard and you will have to leave the amplifier turned on.

    HTH.

    John Dawson (Arcam)

    PS - out of interest what impedance are your Grado headphones and what is the quoted sensitivity?
     
  17. sceptic

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    I use a Slee Solo 2004 headphone amp with Senn HD600 and Sony CD1700 cans. While the sound is undeniably good I don't feel that there is much difference when listening through the headphone socket of my NAD C350 amp.
    Considering that the Solo cost £460 I certainly wish that I had spent the money elsewhere. I feel it's the worst value for money piece of my HiFi/AV kit.
    I would advise anyone thinking of getting a headphone amp to audition carefully before buying and not get carried away by reviews and recommendations on forums. I guess the last bit applies to all kit though.
     
  18. Crocodile JD

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    FAO: John Dawson

    Hi John

    Any comments on my previous post?

    Cheers

    Croc
     
  19. Crocodile JD

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    John

    I found this on ESP web site is it suitable, my cans (Senn 590) are 120ohm BTW

    I would have attached a picture of the schematic if I knew how?

    Croc
     
  20. arcamalpha

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    Hi John, because I am technically challenged to say the least! what you said kinda went over my head but I got the jist that it is a protection system in place?
    So that is why I need to leave my a85 on, thanks for the explanation John.
    Now to my headphones, grado sr60's, they are nominal impedance of 32 ohms, as for sensitivity, just looking at the box, is it SPL 1mV you refer to? because other than that it doesnt actually say " sensitivity ".
    But, the SPL 1mV, whatever that means, is 98.
    I'd just like to say that it makes a change to see people who actually work for the manufacturers visiting sites such as this and offering their unpaid advice in their own free time, well done to you :clap:
    Also, sceptic, I am fully behind what you say regarding auditioning kit.
    Where I bought the project headbox from, I was under no pressure to buy, they advised I just bring some of my fav music along, because they had my amp and cd set up ready, all it was a case of was hooking my cans up to the project and putting the cd on.
    It can be very easy to get drawn in by all the spin that magazines write, but at the end of the day, find a good dealer, and if it isnt music to YOUR ears, dont part with the hard earned bucks.
    Thanks again John and guys.
     
  21. Crocodile JD

    Crocodile JD
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    ....Err...OK...I'll....Err..... just....Err... tootle off then... :rolleyes:
     
  22. rozzar

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    thats very interesting. I used to have the HD580s and yes, they're very good cans- incredibly good for dozing off to, but no match for JM Lab Electras (905s in my case). I'd say my old Stax Lambda Novas were pretty close to the Electras.... maybe your JM Labs aren't setup right because they should walk all over the '580s...
     
  23. Daneel

    Daneel
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    I've no idea what the Stax Lamda Novas are but I've very happy with the sound of both my Electras and my canns. The room isn't perfect but I've put a lot of work into getting a good sound out of the 926s.

    I consider the 580s to be very, very good, there isn't much I can criticise about them at all that isn't inherent to headphones, so saying they run close to my mains is a compliment IMO.

    :)
     
  24. alexs2

    alexs2
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    Stax Lamda Nova...very nice set of electrostatic phones....review here

    http://www.stereophile.com/accessoryreviews/889/

    My own experience of other Stax models was of a beautifully detailed sound,but not necessarily the easiest things to wear!
     
  25. rozzar

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    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 :)
     
  26. alexs2

    alexs2
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    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!
     
  27. Jonesthegas

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    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
     
  28. Crocodile JD

    Crocodile JD
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    Jonesthegas wrote:
    John Dawson wrote:
    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
     
  29. Crocodile JD

    Crocodile JD
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    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?
    [​IMG] 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
     
  30. John Dawson

    John Dawson
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    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)
     

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