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francolargo  
#1 Posted : Tuesday, October 5, 2010 11:59:32 AM(UTC)
francolargo

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Greetings group! I have a couple of basic questions about the best implementation for my Legato. [I 'do biology' so your professional advice is a huge help!] Thanks in advance for any theory and/or practical advice.

With amps, of course, mono-block transformer configurations are generally preferred. But for signal generation and I/V processing, how much 'interference' could result if the same transformer supplied both a Placid BP and an LCDPS? In the chassis for which my Legato is intended I already have a 25VA 15v trafo dedicated to running one LCDPS that supplies 3 Opus DACs. ...not much load... Installing another separate 15v trafo dedicated to a single PlacidBP/Legato is not a problem, but that would be the 4th trafo in the chassis, which begins to seem like 'over-kill'!
1. Would you expect any audible differences in either the Legato or in the Opus boards if their separate supplies (again, a Placid and a LCDPS) were to share the same transformer?
2. If I were to share a trafo, would it be advisable to adjust the Placid to shunt a bit more current (and how much)? I have Legato version 1.0.3 and I raised the output (to about 1.9V?) with 180R and 390R resistors but didn't install the buffer or power the Bal-SE circuit.
3. Considering the balanced design of the Legato and (Buffalo plus Opus) DAC circuits, would it be advisable to barrier-off the trafos (either 3 or 4 small toroids) and perhaps their power boards in one area of the enclosure?
4. I'm intrigued by the notion of paralleling the BS250s on the Legato! But finding good quality matching parts - not so simple! Brian or Russ, any chance that TPA could offer a strip of 12 FETs to those of us inclined to experiment with our version 1 boards?

Many thanks in advance!

Frank in Mpls.

Edited by user Tuesday, October 5, 2010 12:05:34 PM(UTC)  | Reason: Not specified

Brian Donegan  
#2 Posted : Tuesday, October 5, 2010 1:27:30 PM(UTC)
Brian Donegan

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1. You can't share a transformer between a dual supply and a bipolar supply.

2. See 1

3. The balanced design makes it more immune to noise from the transformers.

4. Possibly...
francolargo  
#3 Posted : Tuesday, October 5, 2010 2:51:50 PM(UTC)
francolargo

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Brian Donegan wrote:
1. You can't share a transformer between a dual supply and a bipolar supply.


You probably just prevented some smoke! Anxious

Brian Donegan wrote:
4. Possibly...


Khuul! When the 2.x series is finalized we'll see where things stand.

Thanks Brian!
MartinC700  
#4 Posted : Wednesday, October 6, 2010 12:16:20 AM(UTC)
MartinC700

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francolargo wrote:
4. I'm intrigued by the notion of paralleling the BS250s on the Legato! But finding good quality matching parts - not so simple! Brian or Russ, any chance that TPA could offer a strip of 12 FETs to those of us inclined to experiment with our version 1 boards?


Not sure you would need to match the FET's, Russ or Brian, can yo comment on the matching need, or lack of? I have 12 more FET's on order from Mouser and am planning the Legato I to Legato II conversion.

Regards
Brian Donegan  
#5 Posted : Wednesday, October 6, 2010 6:25:26 AM(UTC)
Brian Donegan

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Sorry, meant to mention that... No need to match.
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