Bosoz as head amp?

protos · 5th November 2002, 12:04 PM

I was wondering if the BOSOZ would drive headphones very well, let's say the Sennheiser 600 I think around 300 ohms. I am in the process of building one right now and I thought if this was possible I could add an output switch which would divert the output to a headphone socket.

paulb · 5th November 2002, 12:17 PM

We've covered this ground before (do a search). You'll need to cut up your headphone cord and use a different connector to drive each channel differentially - the BOSOZ has a balanced output and headphones normally use a common center channel.

protos · 5th November 2002, 03:25 PM

Thanks, saw the thread now.
However in order to avoid modifying the cords wouldn't it be better to have an output switch that shorts - to ground and shunts the output to a dedicated headphone jack?

Possum · 5th November 2002, 03:41 PM

If you don't mind spending the money, HeadRoom at www.headphone.com might sell the balanced Cardas or Clou cables for the Sennheiser HD600. They carry these in support of their balanced-only output Blockhead amplifier (the best amp they carry for headphones).

However, I'll probably just take your approach and feed the unbalanced outputs to a stereo headphone jack.

nar · 5th November 2002, 08:53 PM

It is perfectly possible to drive the headphones differentially,with just a little modification.Cut wires from the terminal jack mostly 3.5 or 6.35mm.Then solder 2 mono plugs,one on each channel.Then you can go directly from the balanced outs of the ZLS.Another little extra adaptor ( mono jacks goin' on a stereo standard one ) allows you to use the headphones as before on conventional equipments

Best regards
Anael

protos · 6th November 2002, 11:18 AM

If I go the common earth route that means that the two power supplies (assuming dual mono construction) will have to be connected at the output to the headphone common earth.
I can't seem to think of a problem arising because of this , what do you think?

tschrama · 6th November 2002, 11:29 AM

The big question first is:

Does your headphone wire has a seperate return wire (or 'ground' or 'neutral' wire) for each channel.

If so, then you can use NAR's idea.

If not, then you may need galvanic isolated amplifiers for each channel...

Did I just cleared things up, or made it worse?

gr,
Thijs

protos · 6th November 2002, 02:11 PM

I am confused with your suggestion thijs.

Assuming I don't want to drive the cans differentially using the + and - from each channel separately, what harm can it do if convert the balanced out to unbalanced by shorting - to earth and then connecting the two channels earths thru the common earth return of the 3-pole jack of a headphone?

skaara · 6th November 2002, 02:12 PM

If you want to drive heamphones differentially you need two wires for each channel.

If there are only three wires for both channels you cant drive them differentially, but only single ended.

5th November 2002, 12:04 PM	#1
protos diyAudio Member Join Date: Mar 2002 Location: Athens+Addis Ababa	Bosoz as head amp? I was wondering if the BOSOZ would drive headphones very well, let's say the Sennheiser 600 I think around 300 ohms. I am in the process of building one right now and I thought if this was possible I could add an output switch which would divert the output to a headphone socket.

5th November 2002, 08:53 PM	#5
nar diyAudio Member Join Date: Apr 2002 Location: near the sea	It is perfectly possible to drive the headphones differentially,with just a little modification.Cut wires from the terminal jack mostly 3.5 or 6.35mm.Then solder 2 mono plugs,one on each channel.Then you can go directly from the balanced outs of the ZLS.Another little extra adaptor ( mono jacks goin' on a stereo standard one ) allows you to use the headphones as before on conventional equipments Best regards Anael __________________ "... Audio needs the thinnest wire ..." Rowan McCombe "Just 'cause they can't hear or sense it themselves doesn't mean you can't !" Allen Wright

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5th November 2002, 12:17 PM	#2
paulb diyAudio Member Join Date: Jun 2001 Location: Calgary	We've covered this ground before (do a search). You'll need to cut up your headphone cord and use a different connector to drive each channel differentially - the BOSOZ has a balanced output and headphones normally use a common center channel.

5th November 2002, 03:25 PM	#3
protos diyAudio Member Join Date: Mar 2002 Location: Athens+Addis Ababa	Thanks, saw the thread now. However in order to avoid modifying the cords wouldn't it be better to have an output switch that shorts - to ground and shunts the output to a dedicated headphone jack?

5th November 2002, 03:41 PM	#4
Possum diyAudio Member Join Date: Sep 2001 Location: Redondo Beach, CA	If you don't mind spending the money, HeadRoom at www.headphone.com might sell the balanced Cardas or Clou cables for the Sennheiser HD600. They carry these in support of their balanced-only output Blockhead amplifier (the best amp they carry for headphones). However, I'll probably just take your approach and feed the unbalanced outputs to a stereo headphone jack.

6th November 2002, 11:18 AM	#6
protos diyAudio Member Join Date: Mar 2002 Location: Athens+Addis Ababa	If I go the common earth route that means that the two power supplies (assuming dual mono construction) will have to be connected at the output to the headphone common earth. I can't seem to think of a problem arising because of this , what do you think?

6th November 2002, 11:29 AM	#7
tschrama diyAudio Member Join Date: Jul 2001 Location: The Netherlands	The big question first is: Does your headphone wire has a seperate return wire (or 'ground' or 'neutral' wire) for each channel. If so, then you can use NAR's idea. If not, then you may need galvanic isolated amplifiers for each channel... Did I just cleared things up, or made it worse? gr, Thijs

6th November 2002, 02:11 PM	#8
protos diyAudio Member Join Date: Mar 2002 Location: Athens+Addis Ababa	I am confused with your suggestion thijs. Assuming I don't want to drive the cans differentially using the + and - from each channel separately, what harm can it do if convert the balanced out to unbalanced by shorting - to earth and then connecting the two channels earths thru the common earth return of the 3-pole jack of a headphone?

6th November 2002, 02:12 PM	#9
skaara diyAudio Member Join Date: Jun 2002 Location: Europe, Slovenia	If you want to drive heamphones differentially you need two wires for each channel. If there are only three wires for both channels you cant drive them differentially, but only single ended.

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