Hmmm...
This is very different from my experience. I use a test signal from the Stereophile Test CD 2 to measure for output at 0 dB, and I get a bit over 2.1 volts differential with 187R up top and 820Rx2 on the bottom. My source is the Sonore USB interface feeding I2S to a B-IIIse (sync clocking) from a Linux based server or the Sonore µRendu (prototype).
This is very different from my experience. I use a test signal from the Stereophile Test CD 2 to measure for output at 0 dB, and I get a bit over 2.1 volts differential with 187R up top and 820Rx2 on the bottom. My source is the Sonore USB interface feeding I2S to a B-IIIse (sync clocking) from a Linux based server or the Sonore µRendu (prototype).
Thanks Russ! I'm glad that there is nothing here to worry about because the output levels are just enough for quieter (usually older) recordings.
That scope trace used 2 probes, one on each differential output pin from Legato (0.2 volt/division). I probably used the wrong nomenclature... SE output from Legato (which I don't use) is about twice the numbers in the table.
I'm REALLY enjoying the system! 😀
Frank
Ok cool - yeah you have to measure the difference between the two signals - so double. So actually your differential output (peak to peak) is the same as your SE output. 🙂 2.8VPP is 2VRMS
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Legato and Lundahl - 8kHz cut off
I recently changed amp to Pass F5. The gain is quite low and got some hum when going SE so I put in Lundahls on the input.
When doing measurements I now see that with Legato3, SE output via buffer, I have a tweeter roll-off at 8kHz!
With my second dac with IVY3 I have no issue with this.
I thought the buffered SE output would be able to drive the Lundahls.
Any ideas or hints would be really appreciated 🙂
I recently changed amp to Pass F5. The gain is quite low and got some hum when going SE so I put in Lundahls on the input.
When doing measurements I now see that with Legato3, SE output via buffer, I have a tweeter roll-off at 8kHz!
With my second dac with IVY3 I have no issue with this.
I thought the buffered SE output would be able to drive the Lundahls.
Any ideas or hints would be really appreciated 🙂
Legato 2.5 Optimal Tuning Point
Hi all,
I've been running a Legato 2 board upgraded with Legato 3 parts == identical circuit except for VR1 / VR2 still trim the input offset rather than nulling in the L3 circuit. I use the balanced output only and stock 680/150R values. Placid BP with +-14.5V rails.
After reading all (!!) the pages in this and the tweaks thread I'm confused as to what the optimal operating point is that I should be aiming for.
e.g. Should I wind VR1 / VR2 to GND so the circuit is identical to a L3 and just use symmetrical rails or for best performance should I set the input bias to ~1.7V and/or the output bias to ?? by adjusting the -ve rail?
Can you please share the best operating point you've found for the 680/150R configuration?
@Russ what do you recommend?
many thanks,
Bruce
Hi all,
I've been running a Legato 2 board upgraded with Legato 3 parts == identical circuit except for VR1 / VR2 still trim the input offset rather than nulling in the L3 circuit. I use the balanced output only and stock 680/150R values. Placid BP with +-14.5V rails.
After reading all (!!) the pages in this and the tweaks thread I'm confused as to what the optimal operating point is that I should be aiming for.
e.g. Should I wind VR1 / VR2 to GND so the circuit is identical to a L3 and just use symmetrical rails or for best performance should I set the input bias to ~1.7V and/or the output bias to ?? by adjusting the -ve rail?
Can you please share the best operating point you've found for the 680/150R configuration?
@Russ what do you recommend?
many thanks,
Bruce
That has to be roll-off from the trafo. Legato SE direct into 32R test load and headphone load shows no roll off until well beyond 20khz.
Many thanks for the response, Russ.
Just confirming to GND VR1/VR2 input bias like a L3 circuit is the best?
BTW it makes no sense to drive a trafo with an SE signal when you have a balanced signal to feed it. 🙂
Still if you wish to use the SE output to drive the trafo you could try and remove the output inductor and see if that is interfering with the trafo reactance. You shouldn't need it in that app anyway.
Still if you wish to use the SE output to drive the trafo you could try and remove the output inductor and see if that is interfering with the trafo reactance. You shouldn't need it in that app anyway.
Thanks for your reply Russ!
I did an impedance measurment on the input side of the Lundahl trafo.
What interesting is that exactly at 8kHz the phase goes positive (inductive load I assume).
I would like to use the balanced signal, but I think those output have less power to drive the trafo-load, or?
I will remove L1,L2 on the SE output of Legato3 and see if things improve.
I did an impedance measurment on the input side of the Lundahl trafo.
What interesting is that exactly at 8kHz the phase goes positive (inductive load I assume).
I would like to use the balanced signal, but I think those output have less power to drive the trafo-load, or?
I will remove L1,L2 on the SE output of Legato3 and see if things improve.
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I found the problem!
If I switch off oversamplig and reclocking (SW2, 5) in the Buffalo3 SE I get this phenomena.
Picture below is with oversampling on or off!
Thing is that I somehow liked the non-overampling, more instant and direct sound. No smearing if you understand what I mean. Perhaps more like a NOS 16-bit dac🙂
But of course I want to keep the output above 8kHz😕
brgs
If I switch off oversamplig and reclocking (SW2, 5) in the Buffalo3 SE I get this phenomena.
Picture below is with oversampling on or off!
Thing is that I somehow liked the non-overampling, more instant and direct sound. No smearing if you understand what I mean. Perhaps more like a NOS 16-bit dac🙂
But of course I want to keep the output above 8kHz😕
brgs
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Well I did remove them already, but no difference.
Anyway I will play with oversampling on now. If I want to go back to non-oversampling I'll make sure the sampling freq is higher!
Thanks for your advise🙂
Anyway I will play with oversampling on now. If I want to go back to non-oversampling I'll make sure the sampling freq is higher!
Thanks for your advise🙂
And in the case of ES9018 the signal should be bandlimited to the 1/16 of the fs, otherwise signal aliases will be generated:
- http://www.diyaudio.com/forums/digi...e-reference-dac-8-channel-77.html#post3868811
- http://www.diyaudio.com/forums/digi...e-reference-dac-8-channel-77.html#post3868811