Headphone distribution ...

[ksor]

I need distribution to 4 headphones - just like this Powerplay HA400 - but DIY !

Can you recommend some schematic ?

 

[Rob Flinn]

There's a reason that there aren't a lot of projects for headphone distribution systems, & that is because you can buy the HA400 for £22 UK which means it's hardly worth the effort to build one.    If you add up the parts cost & your labour it would actually be a lot more expensive for you to DIY it.

That said, don't let what I've said put you off building your own headphone distribution if you really want to do it !

 

[ksor]

There's a reason that there aren't a lot of projects for headphone distribution systems, & that is because you can buy the HA400 for £22 UK which means it's hardly worth the effort to build one.    If you add up the parts cost & your labour it would actually be a lot more expensive for you to DIY it.

That said, don't let what I've said put you off building your own headphone distribution if you really want to do it !

Yeah, but it has one big drawback ... you can't get it into your own design, and I want exactly that - and I have no room for the HA400 in my panel  :-\

That's why I ask.

 

[Rob Flinn]

LIke I said don't let me put you off designing/building your own.  I was just explaining why there are not so many projects for what you want round here !

 

[RuudNL]

I have used this in the past:  http://www.groupdiy.com/index.php?topic=47920.msg604187#msg604187

(I used 1N4148 instead of the LED's)

 

[ksor]

I have used this in the past:  http://www.groupdiy.com/index.php?topic=47920.msg604187#msg604187

(I used 1N4148 instead of the LED's)

Oh ... it's way too big for my panel, but the "power amp output" distributed to four plugs will do I think - thx !

 

[ksor]

I have used this in the past:  http://www.groupdiy.com/index.php?topic=47920.msg604187#msg604187

(I used 1N4148 instead of the LED's)

OK - I'll use this amp - what are the purpose of the LED's ?

 

[Rob Flinn]

The led's keep the transistors biased correctly.

 

[Rob Flinn]

The led's keep the transistors biased correctly.  The reason red ones are specified is because the have the needed voltage drop across them, which would be different if you used yellow or green etc.

 

[ksor]

The led's keep the transistors biased correctly.  The reason red ones are specified is because the have the needed voltage drop across them, which would be different if you used yellow or green etc.

Yeah, but why use LEDs ... why not ordinairy diodes - I beleave LEDs are just flashing randomly - misinterpreted as "something is burning inside" the box  ;D

 

[ksor]

I have used this in the past:  http://www.groupdiy.com/index.php?topic=47920.msg604187#msg604187

(I used 1N4148 instead of the LED's)

I've disided to try to use this link for a 4 channel Headphone module but I have some questions:

1) are there some actual updating for the schematic ?

2) should some heatsinks be added to the 135/136 ?

3) can the listed power supply deliver power for 8 of them ? (for a 4 channel I need 8 of these amps)

 

[RuudNL]

1 - The schematic works fine as it is. You can (as I did) use 1N4148 diodes instead of the LED's.
2 - I used small heatsinks in my heaphone amplifier, but the transistors never were hot or even lukewarm.
3 - I think 10 VA is enough for 8 headphones. Suppose the efficiency is 50%, that will give 5 VA audio.
    5 / 8 = 625 mW audio per headphone. That will blow your ears off!!

 

[ksor]

1 - The schematic works fine as it is. You can (as I did) use 1N4148 diodes instead of the LED's.
2 - I used small heatsinks in my heaphone amplifier, but the transistors never were hot or even lukewarm.
3 - I think 10 VA is enough for 8 headphones. Suppose the efficiency is 50%, that will give 5 VA audio.
    5 / 8 = 625 mW audio per headphone. That will blow your ears off!!

OK - oh, it's just fine you have them working !

I'll done some mechanical considerations of where to place the power supply, potmeters, amps and buffer and show them for confirmation here  ;D

Thx !

 

[sodderboy]

You mentioned "panel" a few times- are you building these to mount on a wall panel or in a rack case?  I mention it because you can lower your parts count, board size, and time factor with something like the TDA7268, a stereo IC power amp, or make a single amp based on a larger monolithic and use resistors/pots to distribute.  That is if there is only one source always like the traditional distributed cue system.
Mike

 

[ksor]

You mentioned "panel" a few times- are you building these to mount on a wall panel or in a rack case?  I mention it because you can lower your parts count, board size, and time factor with something like the TDA7268, a stereo IC power amp, or make a single amp based on a larger monolithic and use resistors/pots to distribute.  That is if there is only one source always like the traditional distributed cue system.
Mike

It's planned to mount in my DIY rack placed against a wall but with wheels so I can drive it out on the floor and access the rear of all the units (all just for hobby !)

There is only one source only = 2 outputs on my Terratec Phase 88 rack mounted sound card mounted just over the planned headphone amps.

I'll try find some schematic where the TDA7268 is used - but potmeters for this power is a little expensive, but you'r right about the board sizes !

 

[ksor]

I've done this layout concerning inputbuffers, amps for 4 stereo headphones and powersuply - I placed the PS so long as possible from the input buffers and the inputs of the amps - should it be done otherwise ?

 

[ksor]

Here are the front of the module:

 

[ksor]

Now I've to assemble the 4 X (left + right) amps - should I care anything about balance between the L and R ?

 

[mulletchuck]

Is that 4 headphones in a 19" rack space?    This presonus HP4 is tiny, like 5" across and VERY loud...

 

[ksor]

Is that 4 headphones in a 19" rack space?    This presonus HP4 is tiny, like 5" across and VERY loud...

Yes, it's 4 headphones in a 19" rack - the GYRAF's schematic and else my own design - you can see it here: http://kelds.weebly.com/headphone-amps.html - let Google do the translation for you !

... sorry, the next you write - I don't understand  :-\ ... do you mean I should make it smaller or ...