Legato 3 - Look ma! No caps!

[necplusultra]

OK my bad

populated R25,r26 and works now.

[RollE2k]

By the way, how sensitive is the legato for Input voltage difference between the positive and negative voltage? I'm going for resistor to set voltage, not pots and wonder if it would be +14.90/-15.00 would that just be trimmed out at the output?

And also as said, if i wire the outputs to my linestage without any ground connection, would that be any problem (they are in same case, and i don't want to mix ground from both supplies, but they will all be connected to chassis through a resistor or rectifier bridge)?

[Russ White]

Not very sensitive at all. anything within a volt on either side should be fine.

[nvduybom]

Hello ,

I measure my Legato with all out put Balance & SE is 0.1 mV DC , but When I reset power supply then all value is changed . What is wrong ?

Van Duy

[Russ White]

It could be your PS settling? Its hard to say. if you like open up a thread on the support forum with pictures.

[Erlend Sæterdal]

2013-01-22 21.37.15.jpg


Sorry for posting it here. I could not find the Buffalo tread. On your support side I can not post pictures like this. The toslink make the lock led flashing. I use the 270 series resistor and 100 ohm parrallel. Will it make the difference with 75 ohm ? Or do I have to change anything else ?

[Russ White]

Originally Posted by Erlend Sæterdal

Attachment 326457


Sorry for posting it here. I could not find the Buffalo tread. On your support side I can not post pictures like this. The toslink make the lock led flashing. I use the 270 series resistor and 100 ohm parrallel. Will it make the difference with 75 ohm ? Or do I have to change anything else ?

Reduce the size of the picture and post it on the support forum please.

This is definitely not the right thread.

Still one hint, try tying -IN to GND for that input.

Do not respond in this thread or I will start deleting posts.

Thanks!

Russ

[nvduybom]

Originally Posted by Russ White

It could be your PS settling? Its hard to say. if you like open up a thread on the support forum with pictures.

Thanks for your reply ,

I think it is time warm up of Mosfet and Transistor ?.

I measured all out put is 0V with 200mV DC meter, then I off/on power,the output about 8mV and measured -1.6mV in 5 minute later .

It is normal ? .Can I connect direct to tube pre-amplifier ? .

Van Duy

[Russ White]

It really depends on the amp.

BTW when measured like that the inputs are floating. Which will effect things.

This is why you need to measure again once the DAC is conneted.

If the few mv of warm-up offset is too much your amp then use AC coupling caps.

One other note - the main pair of NPN (QN5 QN6 etc) can be thermally coupled. This should significantly reduce any such drift.

I do this by gluing them together or using heat-shrink tubing etc.

Cheers!
Russ

[avr300]

Originally Posted by Russ White

One other note - the main pair of NPN (QN5 QN6 etc) can be thermally coupled. This should significantly reduce any such drift.

One picture = 1000' of words.

This if from an earlier Legato but the picture is principal.

Sorry for interrupting the threat.