BB 1702 DAC + transformer I/V ?

[inertial]

Hi guys,

Just purchased a pair of Denon DCD1450AR used ( one for me another for my friend). I like it because the Alpha Processor.
They use one BB 1702 for channel.
I was looking on the Sowters page where he has a transformer 8347
specific for 1702.

http://www.sowter.co.uk/specs/8347.htm

I am worried from that frequency graphs, do not seem to my inexpert eyes the best thing one can expect.....
It is slightly rising with frequencies... ( ok vertical division is expanded).
One more, I do not have understood if using a more little value for resistor , performances on the bass are improved ?
What is maximum value that I can use ? 100 ohm or more?

Thanks,
Paolo

[analog_sa]

Originally posted by inertial
Hi guys,

.....
It is slightly rising with frequencies... ( ok vertical division is expanded).

+-0.25db not good enough? To me it seems like a pretty nice transformer. Max value of resistor will depend upon the dac and generally lower values == lower distortion. Cannot imagine why would you want 100ohm or more. It also appears that the transformer core will start saturating above 2mA into 25ohm.

[inertial]

Originally posted by analog_sa



+-0.25db not good enough? To me it seems like a pretty nice transformer.

You are right, maybe I can tolerate it! :-)
Me too seems nice for about 50 pounds!

[i]
Max value of resistor will depend upon the dac and generally lower values == lower distortion.[/B]

Distortion of the DAC , am I right?

[i]
Cannot imagine why would you want 100ohm or more.[/B]

Because I want more Volts!

[i]
It also appears that the transformer core will start saturating above 2mA into 25ohm. [/B]

OK, I understand nada of transformer..
What happens if I put 100 ohm instead 25? ( apart 4 x Volts)
Is it the frequency response the same ?

Thanks ,
Paolo

[inertial]

Ouch! Maybe now I have realized.........
It is no possible employ a resistor > 25 ohms because the transformer
will go in saturation , am I right?

If my calculation is correct, with 25 ohms you will have about only 400mV on the secondary .... ie -12dB than standard CDP output level

Do you know a different transformer ( Lundhall maybe ?) that can tolerate a bigger resistor thus give me a superior output level with the same bandwith ? ( mmmmhhhh a lot of bucks I suppose but! )

thanks,
Paolo

[inertial]

Originally posted by inertial

If my calculation is correct, with 25 ohms you will have about only 400mV on the secondary .... ie -12dB than standard CDP output level

edit:
No, 400mV is about -14 dB ( 1/5) respect 2V

Cheers,
Paolo

[inertial]

Please kind guys,

can you suggest me a very good trasformer ( european if possible) capable to tolerate
a bigger I/V resistor , to say 100-200 ohm, in order to achieve a level on the secondary about 2 Volt?

Very thanks for the help,

Cheers,
Paolo