A NOS 192/24 DAC with the PCM1794 (and WaveIO USB input)

[Sovereign1]

David your absolutely right, but I could never find the cause of the hum, I knew it shodnt be there but I could never get got the bottom of it.
That can be the problem at times when your technical knoedge is limited. I see you don't use cinemags, what is your reasoning here?

 

[smooth dancer]

If I try without the cinamags, must I remove the resistors on output, or keep them but change the value ?

( First of all I will check if there is dc out from the motherboard.)

 

[smooth dancer]

I tried to find the post where doede talks about dc and how much is acceptable when running without trafo and caps on output.

After removing the cinemags, I measure 2.7mv dc on the right channel and 1.2mv on the left.

I measured at speaker out on the poweramps. Is it safe to connect the speakers , or ?

 

[juancho]

David your absolutely right, but I could never find the cause of the hum, I knew it shodnt be there but I could never get got the bottom of it.
That can be the problem at times when your technical knoedge is limited. I see you don't use cinemags, what is your reasoning here?

I didn't think they were better than going direct with 2 boards but I'm persuaded that they work better with 4 or a buffer with one.

I expect to try them again once I've built a buffer sometime next year
David

 

[Redshift187]

2.7mV is most definitely safe at the speaker terminals of the power amp. That's extremely low for DC coupled. I would suspect your amps of being AC coupled, in which case you don't need to worry about capacitors on the DAC output.

 

[dwjames]

If I try without the cinamags, must I remove the resistors on output, or keep them but change the value ?

( First of all I will check if there is dc out from the motherboard.)

You should remove them, otherwise you get cross talk between left and right channels if your amp has a shared gnd

 

[smooth dancer]

Thx James and Redshift.

I will remove the resistors.

thx

 

[smooth dancer]

I made an album that you can view. Work is still in progress for an even better sound.

If you have some tips on how things can be improved on, let me know!

dddac - Imgur

thx

 

[stijn001]

I tried to find the post where doede talks about dc and how much is acceptable when running without trafo and caps on output.

After removing the cinemags, I measure 2.7mv dc on the right channel and 1.2mv on the left.

I measured at speaker out on the poweramps. Is it safe to connect the speakers , or ?

Is this measured at full gain/volume? If so, that is very low. Nice!

 

[Sovereign1]

Nice speakers Smooth Dancer!

 

[smooth dancer]

Is this measured at full gain/volume? If so, that is very low. Nice!

I measured with volume from low and up to max. It was stable at 2.7 mV dc.

 

[smooth dancer]

Nice speakers Smooth Dancer!

Thanks Sovereign

dddac realy rock on this speakers. Even more after disconnecting the cinemags.
Sound seems clearer and bass is more defined.

Give me a couple of weeks, and there will be a shootout against my tweaked Buffalo IIIse dual mono.

 

[stijn001]

Nice speakers Smooth Dancer!

Nice speaker indeed, I bet they "Rock" well..

Btw,. try going POS/NEG on the output, see if that works for you.

 

[smooth dancer]

Nice speaker indeed, I bet they "Rock" well..

Btw,. try going POS/NEG on the output, see if that works for you.

Thx stijn

It is pos/neg I am using , and it works great.

 

[stijn001]

Thx stijn

It is pos/neg I am using , and it works great.

Turn the balance full to either side, either in software or on your pre-amp to check if you get any cross-talk to the other channel.

 

[smooth dancer]

No balance option on my setup. Dddac sounds great now, cheers.

 

[Undarra]

Hi I have a quick question regarding tentlabs shunt regulators. I ordered two 8v ones for the analogue supply. When connected to 12v I get 8.34v output with no load. In circuit they only output 4.6v. They are marked 15v on the back. I've check and double checked connections. Do you think I have been sent 15v ones by mistake and they are not regulating because the input voltage is below 18v if that makes sense. Very disappointed at the moment.

 

[IanS1]

Nah, they are marked 15v because 8v isn't standard, my 8v are the same. If you asked for 8v then that's what Guido would have supplied. Post a photo of your connections.

 

[Undarra]

I haven't got a photo at the moment, but looking at the component side. The left most pin is connected to the Vin pin of the old regulator pad. The centre pin goes to the ground of one of the 100nf caps and the right hand side pin goes to the positive side of the same cap. I have removed the 47uf caps and only left the 100nf decoupling caps and the vcom caps.

 

[IanS1]

Connections seem about right. Are you saying you've removed all 47uF caps before the regulator. What's the voltage at the input side of the reg under load?