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Old 11th March 2013, 04:02 PM   #1571
udailey is offline udailey  United States
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Yeah, I should have had my thinking cap on rather than my lecture cap. Going into a circuit that is inherently balanced probably WOULD be better to have a balanced pre into it.
The noise issue still exists but without hearing it I would guess that balanced into the J would sound better than single ended.
Something that might be tried is a Cinemag 1:1 transformer to go from SE to Bal. These transformers perform incredibly. I tested one on my AP and it was near 0 distortion. Basically the specs were quite a bit better than the datasheet and the sound was wonderful. If I had a pre that was already SE and I wanted BAL then this is a simple fix that costs about 100usd for stereo and sounds fantastic if the SE pre before it also sounds fantastic.
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Old 11th March 2013, 04:06 PM   #1572
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some more info wouldn't make any harm ....

what's between Legato and J ?

link to Legato sch will help , too - there are to much variations for my peanut memory
Your generosity in willing to help is greatly appreciated! Now I'm completely out of time for about a month. But I will get back to it ASAP so any/all advice is welcome. The J input resistors are currently 'stock' values. I would like to drive it directly from the I/V stage of the DAC: http://www.twistedpearaudio.com/docs..._schematic.pdf
Mine is tweaked slightly for higher-than-stock output of about 1.7Vrms.

With only wire between the I/V stage and the amp, it sounds like there is nowhere near enough current entering the A-J...

...back to work here...

Frank
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Old 11th March 2013, 04:10 PM   #1573
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Is that OPA IV. Should be plenty of beef if speakers are somewhat efficient.
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Old 11th March 2013, 04:22 PM   #1574
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Is that OPA IV. Should be plenty of beef if speakers are somewhat efficient.
...that's what I thought... driver efficiency is 89dB/W

IIRC, output impedance of the I/V is about 2k (???)

This I/V sounds very nice directly into a balanced 3886 chip amp in which each side has 10X gain.

BTW, for later, what are the best locations from which to check bias current? ...and any tricks to that?

TIA,

Frank
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Old 11th March 2013, 05:29 PM   #1575
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Frank - if you're willing to toss entire OP shebang on right side and invest in pair of Lundahls , you'll have much better sound - balanced or SE , by your choice

look for AR2's posts regarding that solution
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Old 11th March 2013, 07:18 PM   #1576
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Zm knows of what he speaks. Are you suggesting the Lundahls feed the OPA or just straight IV duties?
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Old 11th March 2013, 07:27 PM   #1577
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I'm suggesting Lundahl after I/V conversion , ditto to attenuator ditto to Aleph J

buffer between attenuator and Aleph J is matter of choice , and inteconnects
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Old 11th March 2013, 07:29 PM   #1578
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Gonna go look that up. Need something to do
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Old 11th March 2013, 07:42 PM   #1579
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disclaimer - I'm not responsible for anything ........
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Old 11th March 2013, 07:45 PM   #1580
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Print is too big.
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