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Hi Diyers, Just wanted to know how would you proceed to test the Legato without the DAC connected in SE Configuration ? My proposal : J1-J4 jumpers for one power supply L+ L- and R+ R- connected to an audio device GND - SE (L&R channels) to the amp (preamp) Switch Relay not mounted Thanks for your tips Alex. Edited by user Tuesday, March 22, 2011 5:25:01 AM(UTC)
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May I ask - why not just connect the DAC ? Edited by user Wednesday, March 23, 2011 10:58:27 AM(UTC)
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Because I try to find out the problem on my LEGATO.
I changed the OPAMP , removed the OMRON switch and still NO SOUND.
Then I start to describe how to proceed step by step in SE setup for a LEGATO + BUFFALO combo to assist people they have the same problem.
AND to find the origin of the problem.
thanks for share.
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Grab a picture and post it. Then lets see.
BTW, what's your supply voltage ?
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breweryfr wrote:
I changed the OPAMP , removed the OMRON switch and still NO SOUND.
Why did you change the op-amp? Did the Legato work before you changed it? Without the Omron relay you won't have any SE sound as the output are connected to ground Try to measure resistance between GND and SE +/- output. Nic
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Nic, the relay short the singal to gnd. So by NOT having the relay connected, you WILL have signal, but no "blob" protection. Edited by user Monday, March 28, 2011 10:56:39 AM(UTC)
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avr300 wrote:Nic, the relay short the singal to gnd. So by NOT having the relay connected, you WILL have signal, but no "blob" protection. I stand corrected.... I'm most familiar with mounted, but unused, Bal/SE stages as my amp is balanced..
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I use one placid bipolar power supply: Vout=14VDC - 400mA When power on (DAC unplugged) I still have no signal on the + and – inputs. VDC measured Have a look on the following pictures "  " "  " "  " "  " J1-4 Jumpers checked ok. Thanks for share your ideas. Edited by user Tuesday, March 29, 2011 4:47:35 AM(UTC)
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That's +14v / 0 / -14v
right ?
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avr300 brings up an excellent question, you are using a Bipolar supply with at least 12V on each (+ and -) rail right? 15V rails are ideal.
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Possibly a stupid question but which terminals are you hooking up your power supply to?. I see that you have fitted all three sets of power supply terminals. You only need to connect your + and - power to the centre set if you are using jumpers. Assuming that you have your + and - power supply set up correctly, then check if you get signal from any of the balanced outputs when the DAC is plugged in and running. Edited by user Tuesday, March 29, 2011 10:54:29 PM(UTC)
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Yes it's +14/0/-14VDC - 400mA from one bipolar power supply.
I just followed the recommendation upon the LEGATO user manual.
"The Legato is intended for supply voltage rails (+ and -) between 10V and 15V, with 12V being a good balance between power dissipation and overall performance."
And when the DAC is plugged I can hear music but with very low signal.
for ihear21kHz: I only use the center terminals to connect the power supply. But the board is prepared for future upgrade.
I will give you a feedback with 15VDC.
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breweryfr wrote:
And when the DAC is plugged I can hear music but with very low signal.
I will give you a feedback with 15VDC.
Maybe your legato is ok and the problem is with the DAC (maybe a phase issue) - photos please :) Raising the supply voltage by 1V is not going to solve anything.
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That is also the reason I posted : To first connect the legato to an audio device and an amp to check everything is fine before using the combo with DAC. Some pics with DAC.     Edited by user Wednesday, March 30, 2011 7:19:32 AM(UTC)
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A quick one - have you ever had sound through the Buffalo ?? I mean, you might have a IVY you have used previously ? If not, lets start with: When you connect your source, does the "LOCK" LED on the DAC light up. Edited by user Wednesday, March 30, 2011 10:17:08 AM(UTC)
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Please establish if you have normal signal from the balanced outputs. You can connect this like a single ended by using either the + or - phase and GND. Also, can you post a photo of the underside of the Legato board. R31 looks like it isn't well soldered.
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Yes, when Buffalo connected to the audio device the lock led is ON. I will give you a feedback for the balanced connection. Here is the R31 board  The complete LEGATO board 
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You will need to go over some of your solder joins again. Some of the connections (inc the links to the DAC module particularly one of the centre pins)look dry. Use a hotter iron. Cheers
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Ok! It will be my task for this week-end.
Do you think I can try the Buffalo unbuffered ?
In SE it will be - and GND joined as mentioned ihear41khz.
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breweryfr wrote:
Do you think I can try the Buffalo unbuffered ?
In SE it will be - and GND joined as mentioned ihear41khz.
You should be able to run it this way. I any case you are just using the balanced output to establish if the problem with the Legato is confined to the balanced to SE conversion stage.
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