Satch & uvos questions

[ozcal]

Hi guys I have a Satch dac with your valve output stage. I am trying to get the best sound possible from the pairing and was wondering if I can take the output lead of the output caps directly to the hot pin of the output rca’s?
Also Thorsten recommended using discrete I/V resistors rather than the ones built into the valve stage. What type and what value of resistor should I use.Where should the discrete resistors be placed and what jumper setting will the valve stage then use.
Thanks in advance,
Gordon

[ThorstenL]

Hi,

Originally Posted by ozcal

Hi guys I have a Satch dac with your valve output stage. I am trying to get the best sound possible from the pairing and was wondering if I can take the output lead of the output caps directly to the hot pin of the output rca’s?

If you like, yes. But make sure the capacitors output connection is also returend to the PCB, for the turn on delay to work. The 100V DC Step on turn on you get otherwise may fry gear that follows...

Originally Posted by ozcal

Also Thorsten recommended using discrete I/V resistors rather than the ones built into the valve stage. What type and what value of resistor should I use.Where should the discrete resistors be placed and what jumper setting will the valve stage then use.

The UTS is fitted with a pair of 100R resistors. For TDA1541 they are used in parallel, so 50 Ohm.

You can use 51 Ohm external (I like Shinkoh Tantalum or Rohpoint NI Copperalloy wirewounds), plus a 10nF capacitor (I like silver mica).

On the UTS the I/V RC is connected to the "Vcom" connection, leave this unconnected (in the Satch it gets linked to ground) and connect the external I/V RC between input and ground.

Ciao T

[ozcal]

Thanks Thorsten.
Just for clarity, if I leave the output cap soldered in place at both ends and take a lead from the output wire of the cap to the hot pin of the rca this will have the same effect as having a return to the board from the hot pin.
Couldn't get a 10nf silver mica cap , will 9.4 nf suffice ?
Thanks,
Gordon

[ThorstenL]

Hi,

Originally Posted by ozcal

Just for clarity, if I leave the output cap soldered in place at both ends and take a lead from the output wire of the cap to the hot pin of the rca this will have the same effect as having a return to the board from the hot pin.

Couldn't get a 10nf silver mica cap , will 9.4 nf suffice ?

Yes and yes...

Ciao T

[ozcal]

Thanks T.

[ozcal]

Hi Thorsten , got the Shinko's and 9.4nf silver mica's.
I just get hiss with the caps is series with the resistors across 'in' and 'gnd'.
With just the resistors across in and gnd I get sound.
What am I doing wrong with caps and is it ok to run the dac with just the resistors in place.
Thanks in advance,
Gordon

[ThorstenL]

Hi,

Originally Posted by ozcal

I just get hiss with the caps is series with the resistors across 'in' and 'gnd'. With just the resistors across in and gnd I get sound.
What am I doing wrong with caps and is it ok to run the dac with just the resistors in place.

The cap and resistor need to be in parallel, not in series...

Ciao T