Legato 3 - Look ma! No caps!

[Russ White]

It sounds to me like there is nothing wrong at all based on the higher rails you are running. The current is proportional to the voltage.

[natzev_i]

Thanks for the clarification, Russ and for bringing me peace of mind!
Out of curiosity I lowered the voltages today to +-12.5 and the current went down to 375mA - not bad. I also noticed supplying Legato with only one Placid consumes a little less current - don't know why.
Also, just to play safe I changed all the power leads with shorter and thicker wires - didn't see any differences though.
Anyway, all voltages are set back to +14.5 and -14.0V - I don't mind some more heat on these cold winter days here and I am starting to enjoy my new BII + L3.1 build!
Thank you very much for all your help and Russ and Brian for producing this great kits!
Ivo

[reactivepower]

I have been running a Legato 3.1 for a while now through the single end output. I really like the sound. It is very nice. One thing I have noticed is that I am hearing more reverberance in the songs. Before Legato I was listening to IVY III. I prefer the sound of the Legato. Really good job guys. Very much appreciated!

[natzev_i]

Hi Russ,
A very strange behavior of the Legato and the two Placids a observed recently.
If I power off and then immediately on the unit it doesn't want to start again. The (+) rail of the second Placid 2.1.2 supplying the BAL/SE stage only is dropping down to 1.5V and the shunted current is 0mA. If I start to raise the supplied current up to 450-500mA something suddenly triggers, I hear how the relay trips and the voltage is back to 14V and I need to lower the current back to its initial 110mA.
I noticed this is mostly happening when:
1. The second Placid voltage is lower than the Placid HD supplying the I/V stage voltage
and/or
2. I turn on the unit immediately before the Placid HD LEDs were turned off completely (the Placid LEDs are fading out much more faster because of the smaller reservoir caps)

Is this a normal behavior and will it disappear if I take a second HD Placid to power the BAL/SE stage, please?

Thanks in advance!
Ivo

[Russ White]

First, It sounds like your simply running out of current, but you may have a fault somewhere because the BAL/SE stage should not be drawing that much current.

Second, you would be better off just using the Placid HD-BP for the whole circuit.

Have you measured how much current the BAL/SE stage is drawing per rail?

[natzev_i]

Russ, thanks for the quick reply!
Yes, the (+) rail is about 55mA and the (-) is 58mA when working correctly.
The problem is not happening often and most of the time everything is running just fine.
I can try with only one Placid HD BP but since you left option for more supplies and I have the old 2.1.2 I just want to use it somehow.
I remembered it happened much more often when I wasn't still nulled the DC offset on the outputs - is this connected somehow? I thought I solved it with correcting the DC offset but obviously I was wrong

[BrianDonegan]

If I power off and then immediately on the unit it doesn't want to start again.

A man goes to the doctor for a sore elbow. He say, "Doc, it hurts when I do this."

The doctor says, "Don't do that."

[natzev_i]

LOL,
I am just concerned if it's normal to "hurt me if I do this" and how to "do it" better "painless"?

[Russ White]

I think the issue may revolve around the power up/off sequence (timing between the two supplies). I can't say I have ever tried it like you are doing it.

[natzev_i]

Hi Russ,
Thank you for the reply.
Since you don't see a major fault I will leave it like this.
If it bothers me much I may buy a second Placid HD BP or use only the one I have now.
Thanks again for the help!

Ivo