New PCM1794A Kit – Balanced Mode Update – Good to Fantastic Sound! - Page 22

AudioSan · 12:56 AM

aha. i'm not going to use a control board. it will be internal DAC for my CDpro2 player.
so what i need to do is short pin 1 and 2 to ground?
right now it's playing with my squeezbox, and its sound wonderfull

beiji · 5th January 2013, 03:30 PM

Hi,
I just have a fda 1B ( buy to a forumer for christmas) and i would like to know :

1) what is the function of the resistors 4R99 ( like R130) behind the analog out of the dac pcm1794 ?

2) I have a clock 11,286Mhz /5V from tentlabs. Can i use it with his own power supply and few modifications of the asrc card ? I want use the dac in a first time only with a cdpro at 44.1 khz.

3)Is that possible to have the schematics of the asrc board ?

bruno

spencer · 5th January 2013, 11:19 PM

The circuit of the ASRC BD is here:
http://www.fetaudio.com/wp-content/u...7-ASRC-Ckt.pdf
Regarding clock to the ASRC, it is a 24.576Mhz XO. Not sure if you can use 11.286Mhz or not.

beiji · 6th January 2013, 10:39 AM

thanks for your answer.
Could you confirm to me i can sold ad1896 or src4192 on the pcb ? Or you have a pcb for each ?
( I have a pcb with ad1896 write on.)

bruno

spencer · 6th January 2013, 02:52 PM

The pcb is designed for AD1896. For SRC4192, there is no MCK out and thus the clock will be using the XO frequency. Thus the soldering is different.

beiji · 6th January 2013, 08:41 PM

I'll try to sold together pin 2 and 3 of the src4192 and so, Mck Out will be the same of XO frequency and that would be working with your pcb.( I have one src4192 in my stock of parts but no ad1896)

and about the function of the resistor 4r99 at the entry of the I/V stage it's a secret ?
In a first time I have think this resistor is using for decrease the entry impedance of the stage i/v but on the MicroCap8 simulation, it's not the case.So I don't understand what is this function.

spencer · 7th January 2013, 12:42 AM

Regarding the output resistors to the IV, there is someone take some measurement and analysis on that in this forum. The findings is that driving a resistor IV up to 50 ohm to ground will not increase the distortion level much.
In my case, I find that putting the resistor in will ensure the distortion will be minimum at all situations. As you can see my design is not driving the output to a virtual ground but rather a positive reference set by the diodes. After doing that, the distortion is more consistent and low. Thus the resistor effect is minimized and become just a crossover of signal. I think if you are interested, you can change the value to see if you can hear any sound difference. I did not tried all possibility as it is a very time consuming process.

apoo · 7th January 2013, 09:42 PM

Has somebody interest for buying my full assembled and working FDA-1B with both ASRC boards? External i2s prepared for WaveIO, Dale i/v resistors and russian PIO capacitors. No output capacitors. Eventually a Schuro encapsulated and ground-shielded toroidal transformer 230v-2x18v 65VA. Delivery from Germany. I´ve payed for all parts, inkl. transformer 560$ / 430€. Please PM me for offers!

apoo

apoo · 8th January 2013, 01:31 PM

I´ve forgotten to say why i´m selling the FDA-1B. Well, I´ve noticed that i personally like more the sound of a NOS DAC.

3rd January 2013, 12:54 AM	#211
AudioSan diyAudio Member Join Date: Feb 2009 Location: Trondheim	aha. i'm not going to use a control board. it will be internal DAC for my CDpro2 player. so what i need to do is short pin 1 and 2 to ground? right now it's playing with my squeezbox, and its sound wonderfull __________________ aleph P1.7 pre. F5 power amp. CDpro2(need DAC). Vivaldi8 speakers Last edited by AudioSan; 3rd January 2013 at 12:56 AM.

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5th January 2013, 03:30 PM	#212
beiji diyAudio Member Join Date: Sep 2006 Location: Lyon	Hi, I just have a fda 1B ( buy to a forumer for christmas) and i would like to know : 1) what is the function of the resistors 4R99 ( like R130) behind the analog out of the dac pcm1794 ? 2) I have a clock 11,286Mhz /5V from tentlabs. Can i use it with his own power supply and few modifications of the asrc card ? I want use the dac in a first time only with a cdpro at 44.1 khz. 3)Is that possible to have the schematics of the asrc board ? bruno

5th January 2013, 11:19 PM	#213
spencer diyAudio Member Join Date: Jun 2004 Location: Hong Kong	The circuit of the ASRC BD is here: http://www.fetaudio.com/wp-content/u...7-ASRC-Ckt.pdf Regarding clock to the ASRC, it is a 24.576Mhz XO. Not sure if you can use 11.286Mhz or not.

6th January 2013, 10:39 AM	#214
beiji diyAudio Member Join Date: Sep 2006 Location: Lyon	thanks for your answer. Could you confirm to me i can sold ad1896 or src4192 on the pcb ? Or you have a pcb for each ? ( I have a pcb with ad1896 write on.) bruno

6th January 2013, 02:52 PM	#215
spencer diyAudio Member Join Date: Jun 2004 Location: Hong Kong	The pcb is designed for AD1896. For SRC4192, there is no MCK out and thus the clock will be using the XO frequency. Thus the soldering is different.

6th January 2013, 08:41 PM	#216
beiji diyAudio Member Join Date: Sep 2006 Location: Lyon	I'll try to sold together pin 2 and 3 of the src4192 and so, Mck Out will be the same of XO frequency and that would be working with your pcb.( I have one src4192 in my stock of parts but no ad1896) and about the function of the resistor 4r99 at the entry of the I/V stage it's a secret ? In a first time I have think this resistor is using for decrease the entry impedance of the stage i/v but on the MicroCap8 simulation, it's not the case.So I don't understand what is this function.

7th January 2013, 12:42 AM	#217
spencer diyAudio Member Join Date: Jun 2004 Location: Hong Kong	Regarding the output resistors to the IV, there is someone take some measurement and analysis on that in this forum. The findings is that driving a resistor IV up to 50 ohm to ground will not increase the distortion level much. In my case, I find that putting the resistor in will ensure the distortion will be minimum at all situations. As you can see my design is not driving the output to a virtual ground but rather a positive reference set by the diodes. After doing that, the distortion is more consistent and low. Thus the resistor effect is minimized and become just a crossover of signal. I think if you are interested, you can change the value to see if you can hear any sound difference. I did not tried all possibility as it is a very time consuming process.

7th January 2013, 09:42 PM	#218
apoo diyAudio Member Join Date: Feb 2012 Location: Germany	Has somebody interest for buying my full assembled and working FDA-1B with both ASRC boards? External i2s prepared for WaveIO, Dale i/v resistors and russian PIO capacitors. No output capacitors. Eventually a Schuro encapsulated and ground-shielded toroidal transformer 230v-2x18v 65VA. Delivery from Germany. I´ve payed for all parts, inkl. transformer 560$ / 430€. Please PM me for offers! apoo

8th January 2013, 01:31 PM	#219
apoo diyAudio Member Join Date: Feb 2012 Location: Germany	I´ve forgotten to say why i´m selling the FDA-1B. Well, I´ve noticed that i personally like more the sound of a NOS DAC.