Legato 3 - Look ma! No caps! - Page 51

RollE2k · 12th November 2012, 10:28 PM

It says this module runs 12-15v, and that 15v is the "best".
Is it anyway possible to make it run even higher voltage, say 18v? and would there be any benefit doing that? (i'm just thinking it wouldn't be necessary burning 9v in the shunt-PSU i have right now, which is why i ask)

Russ White · 13th November 2012, 03:16 PM

It is possible, you may want to tweak some resistor values. You would also need to be sure that the opamp you use for bal/se can handle it.

Personally. I would stay in the 12-15V range.

RollE2k · 13th November 2012, 05:33 PM

I won't be using any opamps, since i will run balanced straight into my linestage (they will share box).
Hmm, then i'll maybe have to look into modifying for higher voltage, since i wouldn't want to increse sinking on the PSU.

RollE2k · 13th November 2012, 08:09 PM

By the way, since these are DC-cancelling - i won't need any caps between the legato and my volcontroller going into the grid of my tubes in the line stage?

Erlend Sæterdal · 04:00 AM

Is it possible to use other resistors around the opamp to get some gain there ? Change the resistors 21-24 to 10 kohm ?

BrianDonegan · 16th November 2012, 01:41 PM

Quote:

Originally Posted by Erlend Sæterdal

Is it possible to use other resistors around the opamp to get some gain there ? Change the resistors 21-24 to 10 kohm ?

Yes. It's a straight forward op-amp stage, so the usual gain calculations can be used.

RollE2k · 18th November 2012, 08:16 PM

By the way, current consumption is said to be 350mA. How much is it approx without the opamps?

avr300 · 19th November 2012, 03:55 PM

Still aprox. 350mA

necplusultra · 24th November 2012, 10:55 PM

Greetings,

so I fired up the legato3 for the first time. I set the ballanced Voltage to 0 but the SE does not fluctuate. It stays at 0 even if I turn the pots completeley left or right. Does this mean that the IC1 is blown?

necplusultra · 25th November 2012, 10:23 AM

Greetings again.

I tried the opamp in an O2 and it confirms to be functionning. I am powering legato3 with salas bib with about 300ma on each +- 15 V rails. The bal section can be trimmed to offset 0 v dc. The SE section cannot be trimmed no matter what direction the wiper on vr3 vr4 are turned. I'm not using the buffer section so I jumpered j5,j6. I don't have anything populated at r25, r26, l1,L2 uc2,uc3.

ANy help would be appreciated.

Note: my system is direct with no caps so I don't want to try it out live before knowing if there is DC at the SE end

13th November 2012, 03:16 PM	#502
Russ White diyAudio Member Join Date: Jan 2005 Location: Nashville, TN, USA	It is possible, you may want to tweak some resistor values. You would also need to be sure that the opamp you use for bal/se can handle it. Personally. I would stay in the 12-15V range. __________________ Less pulp more juice Twisted Pear Audio.

16th November 2012, 03:52 AM	#505
Erlend Sæterdal diyAudio Member Join Date: Mar 2007	Is it possible to use other resistors around the opamp to get some gain there ? Change the resistors 21-24 to 10 kohm ? Last edited by Erlend Sæterdal; 16th November 2012 at 04:00 AM.

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12th November 2012, 10:28 PM	#501
RollE2k diyAudio Member Join Date: Nov 2007	It says this module runs 12-15v, and that 15v is the "best". Is it anyway possible to make it run even higher voltage, say 18v? and would there be any benefit doing that? (i'm just thinking it wouldn't be necessary burning 9v in the shunt-PSU i have right now, which is why i ask)

13th November 2012, 05:33 PM	#503
RollE2k diyAudio Member Join Date: Nov 2007	I won't be using any opamps, since i will run balanced straight into my linestage (they will share box). Hmm, then i'll maybe have to look into modifying for higher voltage, since i wouldn't want to increse sinking on the PSU.

13th November 2012, 08:09 PM	#504
RollE2k diyAudio Member Join Date: Nov 2007	By the way, since these are DC-cancelling - i won't need any caps between the legato and my volcontroller going into the grid of my tubes in the line stage?

18th November 2012, 08:16 PM	#507
RollE2k diyAudio Member Join Date: Nov 2007	By the way, current consumption is said to be 350mA. How much is it approx without the opamps?

19th November 2012, 03:55 PM	#508
avr300 diyAudio Member Join Date: Sep 2005 Location: DK	Still aprox. 350mA

24th November 2012, 10:55 PM	#509
necplusultra diyAudio Member Join Date: Jan 2011 Location: sitting down	Greetings, so I fired up the legato3 for the first time. I set the ballanced Voltage to 0 but the SE does not fluctuate. It stays at 0 even if I turn the pots completeley left or right. Does this mean that the IC1 is blown?

25th November 2012, 10:23 AM	#510
necplusultra diyAudio Member Join Date: Jan 2011 Location: sitting down	Greetings again. I tried the opamp in an O2 and it confirms to be functionning. I am powering legato3 with salas bib with about 300ma on each +- 15 V rails. The bal section can be trimmed to offset 0 v dc. The SE section cannot be trimmed no matter what direction the wiper on vr3 vr4 are turned. I'm not using the buffer section so I jumpered j5,j6. I don't have anything populated at r25, r26, l1,L2 uc2,uc3. ANy help would be appreciated. Note: my system is direct with no caps so I don't want to try it out live before knowing if there is DC at the SE end