Hi, I have the following questions in regards to Legato 3.1.

Supply is +/-15V from Placid HD.
Only balanced connections used, so omitting SE Diamond buffer, SE opamp, switch, resistors R17-R26, R26 and R33 and VR3, VR4. No jumper in J5 and J6?. In the 3.1 Draft Manual it's not very clear as " Completely mitting the opamp and BAL/SE ", it does not list install J5 J6).


Most of the heat dissipation comes from the resistors R1-R4 and R9 to R16. Do these need to be 1/2w, 1w? Can I get away with low PPM high grade 1/4w standing up in a well ventilated box? (Going to 2Vrms and or compensating for channel bundle in the DAC, the parts that calculate are hard to come by in larger than 1/4w and I have a few on hand.) I don't think but worth to ask, if the power dissipation on the resistors would be less since there is no SE parts populated?


Going to 2Vrms, and compensating for the lower output when the Buffalo is in 4 CH mode, I will be using:
R1-R4 ~375ohm (1/4w?)
R9-R16 ~1.68kohm (1/4w?)
C1-C4 ~750pF (?)
Would a mica capacitor work well in C1-C4 such as this:
http://www.mouser.com/Pr...HR6imeh%2fPW5jCaKHzTk%3d
Understanding that the optimum is 1.5v what should one expect from going to 2vrms? THD+N?


I will be building a few of these boards to figure all this out and have some of the parts extra so will get at least one board without the kit to experiment. I would like some recommendation on readily available substitutes and perhaps and upgrade for a few components:
QN1-QN6?
http://www.mouser.com/Se...4DwOM46%2fg9NzWlqQ%3d%3d
http://www.mouser.com/Se...VN%252bMZCp61iKcZg%3d%3d
http://www.mouser.com/Se...q5eNvNWjETC0xY1d6w%3d%3d


Any other components that may result in SQ improvement? For example I have some DC coupling caps with lower ESR, sadly they don't fit.
C5-C6? upgrade?
QP1-QP12 upgrade?

Assuming that DC can be completely removed, but still using the Legato into an input that is sensitive to DC such as Hyphex Ncore 400, do you still recommend a cap on the balanced outputs? (From years of speaker XO upgrades I learned to hate CAP's in the signal path, but could use some Audyn Copper, Jentzen Z super or Silver at a very low value lets say 0.22uF. The higher corner frequency would not matter since these outputs will strictly be driving mid and tweeter. But would like to avoid the cap as much as possible as even the very best ones will "color" the sound.
Same goes for a transformer. (I've learned that by using many different mic pre's with or without).

Thanks!

This should have been a multi part message, but perhaps someone has a BOM that is exactly what I'm looking for.

A,.

Edited by user Sunday, November 30, 2014 11:24:19 PM(UTC)  | Reason: Not specified

Thank you Brian,

Will use 1w, as prescribed.

Ordered a handful of OnSemi BC550CGs.

I do believe both the ICE and nCore will do just find without the ground. But will just have to experiment.

A,.

The more I think about this, this is a nice way to shape the sound. For example a Jentzen Z-Superior would add a nice rendition when connecting to an ICE power amp. 10k on balanced so 5k each leg, you need a fairly large cap (10uF = 3.6Hz) for full range. But in my case not an issue since it's for mids and tweeter only will try some Audyn Coppers at 0.22. (I may even put in a 4 pole swtich so I can go bananas :)

1, No cap, Ground connected (SS Class A amp, 50k cap on input/leg)
2, No cap, No ground (For clean connected to nCore 50k)
3, Cap A, Ground connected (ICE 5k)
4, Cap B, Ground connected (Ncore 50k)

Thank you!

Edited by user Thursday, December 11, 2014 9:52:59 AM(UTC)  | Reason: Not specified

Brian says 1W is necessary, the BOM lists 1/4 and 1/2 watt parts. Russ says 1/4 w Is ok...
From bom, CMF60681R00FHEK/CCF60681RFKE36 1/4 and 1/2 watt parts....confusing...

Sorry my confusion came from the suppliers data, looking at the data sheet I see 1/2w spec, but rated 1W. Bloody hard to find parts...but slowly getting there :) Thanks!

So the boss says it is 1W!!!

---

By far the best still not esoterically priced cap for coupling the Legato is the brand new Audyn True Copper.
The most transparent of them all I tested (8).

Runner ups.
For nice midrange bloom: Jentzen Z Super
For "HD" sound: Jentzen Silver

All of these blow away any box capcs (Wima MKP,FKP, Vishay MKP378, MKP419 etc.), by a large margin. Anything less, you are not getting the full legato effect.

And confirmed, cutting the shield off and no cap is also an option with some amps such as the Hypex an old Threshold Class A amp, which is how I will be using it :)

Edited by user Tuesday, December 30, 2014 8:55:11 PM(UTC)  | Reason: Not specified