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Old 28th March 2005, 05:27 AM   #1
jleaman is offline jleaman  Belgium
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Default Pass X2 Preamp

In this schematic it shows 95V positive and 32V negitive is this correct ?

J
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Old 28th March 2005, 06:03 AM   #2
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HI,

yes this is correct. Because of the current source it is not needed to have a large negative voltage. Most use a lot less than 32Volts.

William
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Old 28th March 2005, 04:29 PM   #3
jleaman is offline jleaman  Belgium
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This means i have to build to psu's..
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Old 28th March 2005, 05:18 PM   #4
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Hi,

no you donīt have to build two PSUīs. You can ofcourse use + and - 90V. Only change the resistor that sets the current and use enough heatsinking.
One advantage of the current source is that you can use lower supply voltage (especially the negative one) for higher efficiency without any performance disadvantages.

William
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Old 28th March 2005, 05:36 PM   #5
jleaman is offline jleaman  Belgium
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Quote:
Originally posted by wuffwaff
Hi,

no you donīt have to build two PSUīs. You can ofcourse use + and - 90V. Only change the resistor that sets the current and use enough heatsinking.
One advantage of the current source is that you can use lower supply voltage (especially the negative one) for higher efficiency without any performance disadvantages.

William

Want to help me then : O )
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Old 28th March 2005, 05:52 PM   #6
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Hi,

yes I can help but first I would like to know why you want to build an "old" design. There are a few X-BOSOZ on the forum (with or without current source) wich do perform better than a BOSOZ with current source.

I would go for one of these.

Building an assymetrical power supply isnīt such a problem either. You only need two (smaller) transformers instead of one and connect the ground togheter or maybe ou can get a transformer with 60V and 20V windings.

William
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Old 28th March 2005, 08:27 PM   #7
jleaman is offline jleaman  Belgium
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Quote:
Originally posted by wuffwaff
Hi,

yes I can help but first I would like to know why you want to build an "old" design. There are a few X-BOSOZ on the forum (with or without current source) wich do perform better than a BOSOZ with current source.

I would go for one of these.

Building an assymetrical power supply isnīt such a problem either. You only need two (smaller) transformers instead of one and connect the ground togheter or maybe ou can get a transformer with 60V and 20V windings.

William

I was just reading and toying with the idea so i can build a nice hi end one for my aleph mini's I might just redo a better layout for teh aleph P1.7 that i have already.. : O )

J
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Old 29th March 2005, 04:41 AM   #8
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Dear William,
Which design you think is better than "X2"(old design ?). please suggest !


Thanks !
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Old 29th March 2005, 06:05 AM   #9
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Well,

a CCS X-BOSOZ for example?

William
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Old 29th March 2005, 07:57 AM   #10
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Dear all

I have long wondered.

Why do we need any negative feedback loop for such a simple single stage gain BOSOZ?
If we see A P1.7, it looks like having a feedback resistor from the drain of the gain FET to its gate. But, I think that the main role of the resistor is to place the drain potential of the gain FET at certain point between the +rail and the ground because it has +rail only. The resistor is not really for the negative feedback (X-feedback), IMHO!!!

I like X2 having NO negative feedback loop.

I am still wondering why we need the X-feedback loop to the simple single stage gain preamp.
Is it really improving the sound in positive way????????

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