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Duette Dual Headphone Amp

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Graham Slee View Drop Down
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    Posted: 15 Jan 2008 at 12:51am
I'm told headphone amps with two output jacks sell much better than those with one - especially in the affordable sub £200 price band.
 
But what happens when the two sets of headphones are of different impedances? I mean, headphone users aren't known for buying two identical pairs on cost grounds alone? On the other hand I'm sure a lot of us have at least a couple of pairs of different headphones?
 
If one pair is low impedance and the other pair is high, then the relative sound pressure levels are going to be different. So much for the value added idea of kitting an amp with two headphone sockets.
 
I guess two amplifiers could be incorporated in one box? That would sort out the impedance difference. But then what if you wanted to play the music loud and your partner wanted to listen quiet? That suggests two volume controls, doesn't it?
 
And maybe you like Rock music while your partner likes Orchestral? So we now require two totally separate amps with separate inputs in the one box.
 
But then you decide you want to listen to the same music Wacko
 
But that means joining the sources - what a mess!
 
OK then, how about if it had a switch that selected separate inputs or commoned inputs? When switched to the common position the other pair of inputs could be used as a chain out. But then in an utopian world it would be great to have both inputs as chained pairs, but in a sub £200 unit that may be stretching it a bit.
 
So, without the utopian bit, do you think such an amp would appeal?
 
The cost of two amps would normally put such an amp beyond £200 GBP, but I've been developing a rather nice sounding discrete bi-polar stage and transistors can be obtained and implemented quite a bit cheaper. It's the hardware after all that is the major cost of any design.
 
Just wondering what to do with this design? How would you reason it out?
 
 
 
 
 
 
Not simple enough for Google-Bot to understand...
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sunhao View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sunhao Quote  Post ReplyReply Direct Link To This Post Posted: 23 Jan 2008 at 4:53am
I think as Graham mentioned, from a practical point of view, a headphone amp with two identical outputs is seldom used in its full potential, meaning, two headsets plugged and heard by two individuals at the same time.
 
Nevertheless some people do favor this design, probably out of a mentality that "more is better". Having a potential function (though seldom fulfilled) is, from a consumer perspective, a good thing. You see this mentality in lots of cases, for instance, many people here (in China) buy cell phones with a variety of functions, and most of them never learn to use even half of them! Still consumers like cell phones with more functions, a common phenomenon, even if they know clearly they will never figure out how to operate all the potential functions.  So having more functions, or more potential usage capabilities, is definitely a plus in the consumer psychology.  Other than that, I see no point of making headphone amps with two identical outputs.
 
But some headphone amps have two different outputs, one designed for high-impedance phones, the other for low-impedance phones. And this might be an interesting idea.


Edited by sunhao - 23 Jan 2008 at 4:59am
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EASY View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote EASY Quote  Post ReplyReply Direct Link To This Post Posted: 23 Jan 2008 at 6:47am
I enjoy sharing the same music with my gf a lot...but mostly during our travel...
I would also like to have 2 outputs on the amps...with our different tastes of headphones...for Orchestra...
but i guess we shall use the sound box  more...hehe...
que sara sara...whatever will be will be
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Sceptre View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Sceptre Quote  Post ReplyReply Direct Link To This Post Posted: 08 Feb 2008 at 12:42pm
Hi Graham.

I often use a pair of headphones with my wife whilst watching a movie or listening to music on aircraft.
My current solution is to use the volume to set the high impedance headset then turn down the volume on the lower impedance unit (often Shure e4c) using the Shure provided inline adjuster.

My thoughts on your 'inclusive' dual head design are confused.  I could differentiate your offering to the young 'want to share this emotion with my love' but even teh iPod advert shows a young couple listening to one earpod each - Remember that Love is a drug!.

I would go with a single output and bundle a high quality Y splitter with a his and hers volume control.  Pink and Blue would sell well here so your vol doesn't get touched by accident.

Dual source dual out with ganging options are overkill.  Mobile listing is exactly that.  Siamese listeners (joined at the amp) will cause major issues (ear pain, broken cables, pedestrian accidents etc.)

Single market must be 95% of your market.
If a $50 unit were produced with a dual in dual out (think two boosteroos and an elastic band) capability, your market would be depleted.

Stick to the knitting, but allow it in kit form too!

Regards
Sceptre

Solo s/n 0806-13 Senn HD600
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 09 Feb 2008 at 11:44pm
OK then, would there be any disadvantage anyone could perceive of in just making it a single output headphone amp - with just a single headphone jack?

(obviously it can't be called a Duette)

I am thinking now of replacing features with performance. Hiving off costs on the features to use better components in a low-compromise design. I'd like to make it no-compromise at all, but in the sub 200 pound (sub 400 dollars) price band, that's nigh-on impossible. However, it would be virtually no-compromise.

And with a bit of luck it'll be discrete. I must have tried about 4 or 5 discrete ideas since starting this thread - based on a bipolar transistor current-feedback design - with differing levels of performance. The one I seem to be settling on shares the same sort of SQ as the rest of the GSPaudio range.

Not simple enough for Google-Bot to understand...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Charley Phogg Quote  Post ReplyReply Direct Link To This Post Posted: 11 Feb 2008 at 12:11am
I think what Sceptre said about a good Y adaptor is spot on. To me it would seem that if two people are listening to the amp at the same time that what SQ you would lose with the adaptor wouldn't be an issue, but would have no effect on it while listening solo ( no pun intended LOL ). Also allowing you to keep cost down from dual amps in one unit.

 But then you would still have the issue of different impedence 'phones. I think the splitter with separate volume  controls sounds good. Where would you lose the least amount of SQ, with a splitter like that, or dual jacks with dual gain switches ( if even possible )? But then your back at added cost.

  I see it as two different markets. The young kids, like my daughter sitting in the back seat of the car with her friend and they share the headphones, which they wouldn't care about sound. Or the dating couple, or married couple without kids that does alot of traveling and if that was their thing, cost wouldn't be an issue.

 Would a line out that they could feed into another amp be feasible?. That way they'd have to buy two Wink.
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sunhao View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sunhao Quote  Post ReplyReply Direct Link To This Post Posted: 11 Feb 2008 at 7:18am
I really wish to see Graham produce a headphone amp that is even better than Solo.  In its price band I believe Solo is unbeatable when driving Sennheiser's and AKG's.
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