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Legato or IVY III outputs for Buffalo II?

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Russ White

Russ White

Member
Joined 2005
twistedpearaudio.com
needsp said:
Hi Russ

One other thing I don't understand. Your reply implies that Legato sounds better at 15V. If R20 etc is adequately rated as you say, why not recommend 15V operation in the manual, rather than 12V?

Thanks

Paul
Click to expand...

The manual is clear why. There is no other reason than heat. If your case is adequately ventilated use 15V. I don't assume all people have adequately ventilated cases.

The manual does assume people will maybe use the buffer, which adds even more heat. So I decided to guide people toward moderation. :)

I am running and have always run 15V with no issues for more than a year. My legato is performing as well as ever. :yes:

Cheers!
Russ
 
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Y

ylingf

Member
Joined 2004
Hi Russ,

I need a SE output, but really don't like to have an opamp in the path for balanced to SE conversion. Since I know my preamp's input impedance is 10K. Is it possible to load the negative output of the balanced output with a 10K resistor, and connect the positive output to the preamp?

Thanks,

Fred
 
qusp

qusp

Member
Joined 2009
I knew the opamp would cause some comments (as did you no doubt ;)) its not an issue for me, as i'm running BAL, but I did wonder a bit about the choice TBH. people buying legato are most often doing so in order to use a no global FB discrete circuit; seems a bit counterproductive (regardless of sound) to ruin that in the last stage with an opamp for SE conversion
 
Russ White

Russ White

Member
Joined 2005
twistedpearaudio.com
qusp said:
I knew the opamp would cause some comments (as did you no doubt ;)) its not an issue for me, as i'm running BAL, but I did wonder a bit about the choice TBH. people buying legato are most often doing so in order to use a no global FB discrete circuit; seems a bit counterproductive (regardless of sound) to ruin that in the last stage with an opamp for SE conversion
Click to expand...

I don't see it that way at all. Here is why. There are two distinct processes involved here.

First we have a symmetrical I/V converter. It is fully discrete with no global NFB. It stands on its own.

Then we have an orthogonal but practical and extremely useful bal/se stage which you the builder can decide to use or not. It is completely optional. The DAC is a balanced DAC, not SE. This I/V stage is a balanced I/V stage.

All of that to say to do BAL/SE with discrete components right would take more space than I had on this PCB, and would not have yielded as good results as what is there right now.

Instead, I took the pragmatic approach and offered the builder options. Use the excellent on-board BAL/SE stage, or do something else with the balanced signal.

One great option would be the Ventus which is a discrete BAl/SE converter. But it is far too large and makes too much heat to put on something like the Legato PCB. :)

So I think the choice was the most logical I could make given the goals regarding form factor etc. :cool:

Cheers!
Russ
 
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NicMac

NicMac

Member
Joined 2009
Paid Member
Russ White said:
One excellent option would be the Ventus which is a discrete BAl/SE converter. But it is far too large and makes too much heat to put on something like the Legato PCB. :)
Click to expand...

Hi Russ,

Would the Ventus used as a BAL/SE converter work better with or without the buffer stage on the Legato? Would the connection need decoupling caps? Can the output DC offset of the Ventus be set (very) close to zero?
I'm considering to use of the Ventus with a dual-mono BII/Legato connected to (balanced) Hypex modules with by-passed buffer stage (input impedance 1k8R, not very tolerant to DC offset).
Last but not least - will the Ventus be re-stocked?

Thanks,
Nic
 
BrianDonegan

BrianDonegan

Member
Joined 2004
twistedpearaudio.com
NicMac said:
Would the Ventus used as a BAL/SE converter work better with or without the buffer stage on the Legato?
Click to expand...

Either would be fine, without would be cooler and easier to power.

Would the connection need decoupling caps?
Click to expand...

No.

Can the output DC offset of the Ventus be set (very) close to zero?
Click to expand...

Yes.

Last but not least - will the Ventus be re-stocked?
Click to expand...

It is getting a little tweaking attention, but will be available again very soon.
 
NicMac

NicMac

Member
Joined 2009
Paid Member
needsp said:
It sounds absolutely superb! Stunningly good! Unbelievably good! I don't say this lightly- it sounds better than the I/V stage I was using (which used a CFT, with a CCS above and below), and I've recently invested a lot of time and effort in that. Believe me it was no slouch sound-wise either- Legato had to be damn good to get my attention!
Click to expand...
Hi Paul,
What are you using for BAL/SE conversion? I seem to recall that you are using a single ended power amp.
Cheers,
Nic
 
NicMac

NicMac

Member
Joined 2009
Paid Member
Thanks Brian,
I will try this combination when the Ventus becomes available again.
I'm doing my best to understand why so many people hate op-amps:confused:
I seem to understand that the Ventus as added value can give me back a bit of the gain that I lost by bypassing the gain stage on the Hypex modules.
Cheers,
Nic
 
C

chipzahoy

Member
Joined 2009
Thank you Brian. The case volume is relatively large (2U), and the slots are directly above the Buffalo.

Oh, and one newbie question regarding the optional buffer. To omit the buffer,do I simply place the jumpers on the black and pink holes at QN8,QN10,QN12,QN13?
 
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Russ White

Russ White

Member
Joined 2005
twistedpearaudio.com
chipzahoy said:
Thank you Brian. The case volume is relatively large (2U), and the slots are directly above the Buffalo.

Oh, and one newbie question regarding the optional buffer. To omit the buffer,do I simply place the jumpers on the black and pink holes at QN8,QN10,QN12,QN13?
Click to expand...
That should be perfectly good ventilation.

I have just seen people put things like this in a completely sealed chassis. That would be a bad move here.

There is a small white line across the pads where the jumper is placed by each Q. The black and purple pad on the PCB illustration.
 
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N

needsp

Member
Joined 2006
NicMac said:
And with your DIY 'Legato"? Just curious.
Nic
Click to expand...

Hi Nic

The same. I used the relevant portion of an IVY III pcb for this.

I'll revisit that circuit in a week or too. In my assessment of Legato I may have underestimated the effect of an upgrade I made to my power amp a couple of weeks ago. Legato is undoubtedly wonderful, but very different to "my" circuit (actually a highly collective effort)- and to IVY III. Listening to Legato this evening, I hear many things I like more than ever before, but also some things I don't like. First thing I'll do is fit BC550B's as Russ recommends- I shouldn't have assumed that ZTX651 would be better without listening first. Then recompare to the other circuit. I suspect I'll find the same- some things better, some worse, but time will tell.

Re ventilation. IMHO Brian/Russ are dead right- a few slots in the casework will do fine. As a valve user the DAC constitutes a very small heat source in my system- roll on winter (for listening purposes :) )

Paul
 
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