Discrete output stage for Sony c222?

[Sheldon]

I have a Sony SCD C222ES. I would like to build a discreet output stage, taking the output from the DAC. I've seen a couple of examples on the net for other players (i.e., www.ultranalog.com), but those appear to require a balanced input. As far as I can tell, the DAC output on this player is single ended. Anyone have suggestions for a good anlalog output stage. Doesn't need to be anything exotic.


Sheldon

[Sheldon]

I may just go with the Ultranalog design and connect the inverting input to ground (com). I was also considering a DC servo to avoid the largish caps on the output. What do I have to consider as regards start-up thumps, etc.?

Sheldon

[rfbrw]

It would help if you named the dac in the C222. Current output dacs and voltage output dacs have different needs.

[Sheldon]

Originally posted by rfbrw
It would help if you named the dac in the C222. Current output dacs and voltage output dacs have different needs.

Ah, yes. Pretty obvious oversight on my part. Anyway, the DAC is a CXD 9658N. It's a combined digital filter and DAC. I haven't been able to find out a whole lot about it yet. I'm guessing it's a voltage output. Each channel feeds a njm2114m-te2 op-amp. Nothing in between except some filtering.

Sheldon

[Extreme_Boky]

Hi Sheldon,

It appears your DAC is voltage - out DAC.

You could also try better quality OP amplifiers like AD826 (simple swap), or excellent AD 8066 (surface mount dual, applicable with adaptor board and ONLY if the voltage is + and - 12V max!) Try also better quality capacitors like WIMA polypropylene for analogue filtering and Black Gates FK for analogue power supply decoupling, or even separate power supply for analogue section!

I had some excellent results with dual triodes, but this requires a lot of hassle - high plate + separate heater and biasing voltages, and large coupling capacitors..... However, if you want to experiment, give them all a go and decide what suits your taste the best!!! Some members report an excellent result obtained with simple transformers – I haven’t tried them yet.

Regards,
Extreme_Boky

[rfbrw]

Originally posted by Sheldon



Ah, yes. Pretty obvious oversight on my part. Anyway, the DAC is a CXD 9658N. It's a combined digital filter and DAC. I haven't been able to find out a whole lot about it yet. I'm guessing it's a voltage output. Each channel feeds a njm2114m-te2 op-amp. Nothing in between except some filtering.

Sheldon

It is a single-ended voltage out dac as used in XB770 SACD player.

This one may need a little modifying as it was meant for a current output dac
My new tube DAC output

You could also try VSE's SLCF www.vacuumstate.com

[Sheldon]

Originally posted by Extreme_Boky
Hi Sheldon,

It appears your DAC is voltage - out DAC.

You could also try better quality OP amplifiers like AD826 (simple swap), or excellent AD 8066 (surface mount dual, applicable with adaptor board and ONLY if the voltage is + and - 12V max!) Try also better quality capacitors like WIMA polypropylene for analogue filtering and Black Gates FK for analogue power supply decoupling, or even separate power supply for analogue section!

I had some excellent results with dual triodes, but this requires a lot of hassle - high plate + separate heater and biasing voltages, and large coupling capacitors..... However, if you want to experiment, give them all a go and decide what suits your taste the best!!! Some members report an excellent result obtained with simple transformers – I haven’t tried them yet.

Regards,
Extreme_Boky

Thanks,

The audio ps in this unit is +/- 7 volts. Most of the discreet type of buffers, preamps tend to run 12-15 volts. Is there a general preference for the higher voltages? I have no problem making a dedicated ps.

Hmm, by using simple transformers, do you mean instead of the output coupling cap?


sheldon

[Extreme_Boky]

Transformers do I to V conversion, natural aliasing filtration, gain and impedance matching, but I question a good impedance matching!!!. Check this site re transformers:
http://www.lundahl.se/

I like higher voltages because i prefer true-to-life sound, a bit like studio monitoring. Higher voltages almost always produce higher slew rates / faster settling times.

However, lower voltages give that warm sound that many people prefer.... not for me.

Power supply is 60 - 70% of global sound quality, yet it's quite often neglected. Try good quality transformer, soft switching fast recovery diodes (RURP3060), Black Gates FK for main storage + storage after voltage regulators. I do not like to bypass these caps with lower value (0.1uF) film types. High frequency decoupling should be done only as close to ICs (transistors) as possible and for this I use 0.1uF / 50V NX Black Gates, again, without any caps in parallel. This is possible due to very high quality of both of these capacitors’ types. Experiment a lot and see for yourself....

AD 8066 is outstanding amplifier and it should work no problems with + and -10V DC. I use them as I to V converters in dual differential PCM1704 configuration, with + and - 12V DC with addition of little heat sinks on top of them, to keep input bias current / conversion error to min. They tend to run hot as you increase voltage to their maximum of 24V DC.

You can try discrete anti aliasing (analogue) filters and see if you like them....

Many people report very good results with simple resistor as I/V converter and discrete amplification with passive filtration, or transformers.

Cheers,
Extreme_Boky

[rfbrw]

Err, it is a voltage out dac so no need for an I/V stage. A simple buffer like the BUF634 will suffice if no additional gain is needed. Or even the AD8066 wired as a follower, assuming it is unity gain stable.

[Extreme_Boky]

It appears your DAC is voltage - out DAC.

I was just explaining my experiance and what other people say on Forums as all the options available for Sheldon to chose from - I never suggested I to V conversion. Try reading again - it'll come to'ya...