Russ, by lookin' at the picture Brian has posted can I assume the following. The BAL-SE conversion is still done by an opamp, the DC cancellation is done at the diamond buffer ??
1) Yes.
2) No. 🙂
There are two places where DC cancellation occurs. One pot trims the differential offset from the discrete I/V converter.
The other pot trims the DC error from op-amp and its Rs to zero. So that SE output can have absolutely zero offset.
this is actually playing to the strengths of the two sections. The I/V stage employing no feedback, and the BAL/SE stage using only as much as it needs while referencing the output directly to GND.
Those using the Buffalo dual mono with balanced outputs will have a real treat with the Legato 3.1.
Cheers!
Russ
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Do you mean the regular Placid BP? Or the new Placid HD-BP?
Placid HD-BP can very easily do that. Even a regular Plaicd BP can so long as you use a 20 ro 10R pot for VR1 and VR2.
Thanks Russ, yes I meant Placid PB, I believe that many people are interested in to the new buffer, but maybe for the moment, as me, they don't want to change power supply. That's why I asked if +-12V and 300 mA are sufficient to drive Legato 3. And I know that Placid BP con easily do. Placid BP already sports 20R pot for VR1 and VR2.
Thanks again
gianluca
Hi Guys,
Not being an engineer, I need some specific guidelines on power routing within my DAC. In general, heat and ventillation is going to become a greater issue as more power is used/shunted and I'm dealing with that issue now. My power supplies, Legato, and Tridents are making too much heat to put the top on the case.
For WAF and my own peace of mind when the DAC goes into its final close quarters, I'll be mounting two quiet exhaust fans atop the rack-mount case. [Two fans rather than one merely because I already cut two correctly-sized holes hoping wide-open fan grilles would permit sufficient convective ventilation. No go. 😱] 800 RPM ball bearing fans dialed from 12 V down to 10 V are silent and vibration free. Power will come from an add-on wall wart plugged into the DAC back panel, switched at the front panel and sent on to the fans. Wall warts are switching circuits that are notoriously 'dirty', right?
Two-part question:
1. Is there any problem running that 'dirty' DC power near the Buffalo2/Trident or the Opus boards or with those power wires intersecting balanced signal lines?
2. Would any additional filtration or shielding of that power within the chassis be advisable and if so, which?
What I'm hearing is SO superb, I don't want to take any chances of messing it up in order to keep everything cool! Thanks in advance for your advice!
Frank
Not being an engineer, I need some specific guidelines on power routing within my DAC. In general, heat and ventillation is going to become a greater issue as more power is used/shunted and I'm dealing with that issue now. My power supplies, Legato, and Tridents are making too much heat to put the top on the case.
For WAF and my own peace of mind when the DAC goes into its final close quarters, I'll be mounting two quiet exhaust fans atop the rack-mount case. [Two fans rather than one merely because I already cut two correctly-sized holes hoping wide-open fan grilles would permit sufficient convective ventilation. No go. 😱] 800 RPM ball bearing fans dialed from 12 V down to 10 V are silent and vibration free. Power will come from an add-on wall wart plugged into the DAC back panel, switched at the front panel and sent on to the fans. Wall warts are switching circuits that are notoriously 'dirty', right?
Two-part question:
1. Is there any problem running that 'dirty' DC power near the Buffalo2/Trident or the Opus boards or with those power wires intersecting balanced signal lines?
2. Would any additional filtration or shielding of that power within the chassis be advisable and if so, which?
What I'm hearing is SO superb, I don't want to take any chances of messing it up in order to keep everything cool! Thanks in advance for your advice!
Frank
There are lot of good on-line resources regarding power routing, Its a complex subject and responding thoroughly would be more than I could do in a post. I would recommend you Google a bit and see what you can learn. Also there s always going to be a bit of trial and error. Do what looks the most reasonable or practical, and move on from there.
As for cooling, you should not need any fans, and I would not use them. You may just want to make sure you have adequate ventilation slots top and bottom of your case.
Cheers!
Russ
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Perhaps the lessons in my case are a) to not mount power supply boards too close to other boards so as to limit air circulation from below and b) to not scrimp on headroom over the heatsinks. Live and learn...
The enjoyment of sound like this is definitely worth whatever it takes... 😀 Thanks again Russ.
Frank
The data, FWIW:
1. heatsink area for QP1 of the Placid was ~doubled.
2. over 50% of the case lid over Placid BP, Placid, and Legato was opened.
3. Stable temps measured atop the Placid QP1 heatsink as follows:
Ambient -> 21C
Case lid in place -> 82C
No case lid -> 70C
Low speed exhaust fans resting atop case lid -> 46C
The enjoyment of sound like this is definitely worth whatever it takes... 😀 Thanks again Russ.
Frank
The data, FWIW:
1. heatsink area for QP1 of the Placid was ~doubled.
2. over 50% of the case lid over Placid BP, Placid, and Legato was opened.
3. Stable temps measured atop the Placid QP1 heatsink as follows:
Ambient -> 21C
Case lid in place -> 82C
No case lid -> 70C
Low speed exhaust fans resting atop case lid -> 46C
Russ, it sounds like Brian is busily putting together the Legato 3 kits. Is there any chance we can get a sneak peek at the schematic while they are being prepared? A few of us would be quite interested to see what the new changes are 🙂
I feel the lack of a "Like" button, as Facebook does 😎
In other words, another one interested in looking at the sch.
Sennheiser HD650
Russ - Would the L3 work well with Sennheiser HD-650 headphones particularly if they have XLR plugs?
Russ - Would the L3 work well with Sennheiser HD-650 headphones particularly if they have XLR plugs?
input impedance
What's the input impedance of that version?
Can it be matched with a DCB1?
Thanks
What's the input impedance of that version?
Can it be matched with a DCB1?
Thanks
Less than half an ohm(actually much less). 🙂
You shouldn't need anything after the Legato 3/3.1 when used with Buf II and Volumite. Just a power amp.
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It works wonderfully into HD-650(or and Senn. can) but I would not wire it balanced unless you are going dual mono. Because it is the SE output that is buffered, but in dual mono the SE outputs become differential output.
order?
Happy to know that.
Actually I already have a DCB1, that's why I asked.
Beside, I didn't see any Legato 3 on Twisted Pear website for making an order. Did I miss something?
Happy to know that.
Actually I already have a DCB1, that's why I asked.
Beside, I didn't see any Legato 3 on Twisted Pear website for making an order. Did I miss something?
