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Old 12th March 2003, 08:48 AM   #11
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ROTFLMAO

Hi Frank..

I'll take your word for it..However..a pf86 is still 5 times cheaper than the svet ef86..

Call me cheap!

Regards,
Bas
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Old 19th March 2003, 02:47 PM   #12
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Is the a 1meg grid resistor a problem for the preceding stage?

I am assuming that the differential op-amp stage is the first...and maybe only stage after the dacs...

So I guess I should ask if a 1meg impedance is a problem for the dac?

I saw the posts on the other dac thread here at tubes...saw figures like 6ohm...or are they talking about other things here?

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Old 19th March 2003, 03:09 PM   #13
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Default EF86

Hi,

Quote:
Is the a 1meg grid resistor a problem for the preceding stage?
If the EF86 is the input of an amplifier I would lower it to 100K.

OTOH, if a stage is directly preceding it and wiring can be kept to a minimum, I would go for the 1Meg.

Quote:
So I guess I should ask if a 1meg impedance is a problem for the dac?
What are you feeding the EF86, you don't use a xformer?

Quote:
I saw the posts on the other dac thread here at tubes...saw figures like 6ohm...or are they talking about other things here?
The 6 Ohm R does the I/V conversion at the input of the xformer.

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Old 19th March 2003, 03:14 PM   #14
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Hi Frank,

Thanks for helping.

Quote:
What are you feeding the EF86, you don't use a xformer?
I am thinking that what I am feeding the EF86 is the same signal that goes to the differential op-amps..NE5532. So I guess the I/V conversion..(If any) has allready taken place.

Essentially I am replacing the NE5532 with an EF86 differential stage.

Unfortunately I don't have a schematic of my cd player.

Cheers,
Bas
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Old 27th March 2003, 07:56 AM   #15
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Default Eureka...It works..

Last night I fired up my CD player with the PF86 differential output stage.

To my complete amazement it worked!!!!

Will borrow a digital camara next week and post pictures..

Sound improvement was not the day and night difference I was expecting. Instruments sound more like real instruments...was about the only improvement I heard...Bass seemed a little less


Still have some noise issues...I suspect the toro´dal power transformer...it's the same one I used for a preamp that made the same noise

Filament supply is DC...star earthing is being used.

Anyway...am a happy camper...

Cheers,
Bas
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Old 27th March 2003, 09:24 AM   #16
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Default The schematic

CCS is a depletion mode mosfet (DN2540) as used by K&K audio.
Attached Images
File Type: gif pf86diff.gif (6.4 KB, 260 views)
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Old 28th March 2003, 12:47 AM   #17
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Default IF YOU ALLOW ME...

Hi,

Quote:
Still have some noise issues...I suspect the toro´dal power transformer...
If I may say so, try to avoid toroids in digital circuits.

Cheers,
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Old 28th March 2003, 09:47 AM   #18
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Hi Frank,

Ofcourse you may say so.

But I had it lying about... :-)

And it is shielded magnetically by a mu-metal shield...electrostatic shield and outside the cd player.. :-)

And it made the same noise when in the preamp.

Cheers,
Bas
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Old 29th March 2003, 09:10 PM   #19
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pics
http://home.zonnet.nl/horneman/pf86dif.htm
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Old 31st March 2003, 12:41 PM   #20
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Hi Bas,

Glad to know your CDP is working You seemed to be a purist, simple circuit fanatic. Then your biggest homework is in the DAC upward
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