Mod done !
I have used resistors of 194R (what I had at hand, I changed R1/../R4), and the result is absolutely amazing, Legato II sounds liquid, full of controlled bass, beautiful timbre on instruments ...
Now it is time for trying the Tridents. I got the BuffII Trident kit, wonder where I have to put every resistor that comes with every regulator ... maybe soldered at the ferrite beds ?
Thank you Russ, excellent job !
best regards
Pepe
I have used resistors of 194R (what I had at hand, I changed R1/../R4), and the result is absolutely amazing, Legato II sounds liquid, full of controlled bass, beautiful timbre on instruments ...
Now it is time for trying the Tridents. I got the BuffII Trident kit, wonder where I have to put every resistor that comes with every regulator ... maybe soldered at the ferrite beds ?
Thank you Russ, excellent job !
best regards
Pepe
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You have to solder the resistors on the Trident PCB itself.
There are 2 small holes. You can choose to solder at the back or front of the PCB.
These resistors do get hot when in use.
There are 2 small holes. You can choose to solder at the back or front of the PCB.
These resistors do get hot when in use.
Russ, Brian?
I had one DAC circuit designer suggest to me that the Legato "should" have small (50-100 ohms) series resistors on its output to provide damping. His assertion was that these would result in better sound, specifically better handling of sibillance caused by transmission line effects on the output cabling.
Now I do not hear any problems with the Legato, but this change is easy to try. Do you think there is any validity to this designers opinion?
I guess the downside would be added output impedance, right?
I had one DAC circuit designer suggest to me that the Legato "should" have small (50-100 ohms) series resistors on its output to provide damping. His assertion was that these would result in better sound, specifically better handling of sibillance caused by transmission line effects on the output cabling.
Now I do not hear any problems with the Legato, but this change is easy to try. Do you think there is any validity to this designers opinion?
I guess the downside would be added output impedance, right?
Generally he is correct. In fact you will notice I do use them in other circuits and at the BAL/SE output. But no changes at all at the I/V end are required as output impedance is already in that range at that stage. But feel free to add them if it makes you feel good. 
This is something we think about from the start. Not an after thought.
This is something we think about from the start. Not an after thought.
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About output I have to use SE outputs or balanced outputs connecting the unused output to GND?
The XT2575:s (my favorite low power resistor) seem to be a bit too "weak" to handle the heat. I am looking at ordering some TX220Z instead. They can handle 1.5W in free air.
You can use either SE or the balanced outputs. If you use the balanced out (+out and GND), DO NOT connect the -OUT to GND.
I have a couple of Legatos on way shortly and some spare boards for when I completely wreck one..
Could I just ask a quick question please re the multi turn trimmer - does it have to be .5W or will a .25W be ok to do the job please? If I cannot get away with a .25 then I guess once its been running for a while I can just measure what it's set at and replace with a fixed.
Could I just ask a quick question please re the multi turn trimmer - does it have to be .5W or will a .25W be ok to do the job please? If I cannot get away with a .25 then I guess once its been running for a while I can just measure what it's set at and replace with a fixed.
I'd appreciate any comments on this small matter. I finally got around to swapping resistors in my Legato v1.03 - prompted by the failure of a 1W 390R PRP9372 in the 'upper' position. I changed from 180R/390R to 150R/2X680R. [I left voltages at my previous favorite settings: +14.5, -14.9.]
At equal volumes in my all-balanced system, lowering the Legato output has somewhat compressed sonic dynamics. This seems preferable for a few high gain tracks and/or hot vocals, but is definitely less engaging on most instrumental program material. Drum 'impact' and orchestral 'zing' seem most affected. At the same time, a few solo instruments with tricky timbre/harmonics are sounding a bit more natural (e.g. oboe, cello). Overall, though - a little less ..., a little less "wow!"
Would the 3 transistors in parallel (in Legato version 2) help in this regard? I'll live with this for a while and see how it feels, though I suspect I'll want more "hi-fi juice" in the final configuration...
Frank / Mpls.
Hi Frank..
Interesting. Is it placebo?
Oh, btw, check voltage before coupling caps. Are you still in "sweetspot" ?
Placebo is quite possible!
However, I had used the board a fair amount at the higher output, so i feel well acquainted with the reference tracks. [and yes, voltage was/is exactly half of AVCC...]I quite agree. In some respects it sounds more refined as well as more restrained. Maybe a little extra volume is all I need!
I'll also re-adjust the plus and minus voltages from the Placid, which I find drop about 2% during warmup. Regards,
Frank/Mpls.
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My understanding is that changing the value for R1-4 will also affect the corner frequency of the low pass filter (with C1-4). This may have an impact on what you are hearing. On my new build (Legato 2) I am running 180R for R1-4, combined with 10nF REL polystyrenes for C1-4-have not heard it yet though...
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