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Twistedpair  
#1 Posted : Thursday, March 7, 2013 8:21:08 AM(UTC)
Twistedpair

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Hi again,
I asked about Ivy vs Legato a few months ago, and finally after some reading and procrastination, I'm poised to order a Legato.

Initially I was worried about the Legato 3.1's DC offset, since my "Charlize 2" T-amp has capless inputs, and the developer warns not to give it any DC -
http://diyparadise.com/charlize2.html
But the supplier of my fullrange speakers (MA A7.3) recommends this as an opportunity to add coupling capacitors to the amplifier inputs which will act as a 50 Hz high pass filter suitable for the speaker drivers. His calculated value for the caps in this case is 0.16 uF.

So I now intend to add 0.15 uF capacitors to the Charlize 2 inputs, but I'm new to this, and the choice of audiophile caps is bewildering.
Could someone recommend input capacitors for my situation, please - at a price-point of no more than approx $50 a pair?

I did some Googling and reading; it appears that the name-brand teflon caps and oil caps are pricey.
But Mundorf Polypropylene caps ("MCAP Supreme") are more affordable.
Or what about MKP caps?
Or Russian K72 teflon?
Or Russian K40Y PIO?

Or should I post this question on the diyaudio forum?

Thanks
Brian Donegan  
#2 Posted : Thursday, March 7, 2013 12:40:40 PM(UTC)
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Since your amp has single-ended inputs, you don't need to worry about DC, sine the Legato's SE outputs do not have DC offset.
Twistedpair  
#3 Posted : Friday, March 8, 2013 10:47:29 AM(UTC)
Twistedpair

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Thanks Brian,
Can you explain this further, please? In the Legato User Manual I see this on page 3:

"First Run and Initial Adjustment
...
5. If the BAL/SE stage is used adjust VR3 and VR4 until the SE output on each side is at 0VDC."
Brian Donegan  
#4 Posted : Friday, March 8, 2013 1:13:23 PM(UTC)
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Correct. This step will remove any DC offset at the outputs.
SCompRacer  
#5 Posted : Friday, March 8, 2013 5:08:15 PM(UTC)
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Originally Posted by: Twistedpair Go to Quoted Post

Could someone recommend input capacitors for my situation, please - at a price-point of no more than approx $50 a pair?



Thanks


Greetings Twistedpair. That is a question you can get many different answers to, if you were going to use them. I have a Legato and recently added coupling caps for the common mode DC (between balanced GND and pos/neg). DC is nulled on SE and between pos/neg of balanced out. Initially I lifted GND of balanced out and it worked with my balanced pre but I got nasty pops when switching between sources. With the GND connected, no nasty pops.

I've used Mundorf MKP's for coupling caps in a modded DAC. I have a friend that uses WIMA MKC4 and Phillips MKC. Also Panasonic ECQ-F. Currently I am using some Radio Shack film caps at $2 each. Haven't had much time to listen but nothing bad has happened that I can tell. Was thinking of some Sonicaps as I have a couple 2.0uf gen 1's laying around, just need two more. I was told they would make my DAC sound strident.

I've been told Dynamicaps are good. Those were ~$26 each in the 2uf value I would use. If you could get a definition from an engineer of what makes for a 'good' film cap we'd be golden.

Edited by user Friday, March 8, 2013 5:21:52 PM(UTC)  | Reason: Not specified

Brian Donegan  
#6 Posted : Friday, March 8, 2013 7:50:56 PM(UTC)
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Just to reiterate, if you are using the Legato's SE outputs, there will be no DC-offset, once the Legato is properly adjusted, so no caps are required.

Edited by user Friday, March 8, 2013 7:52:34 PM(UTC)  | Reason: Not specified

Twistedpair  
#7 Posted : Saturday, March 9, 2013 12:40:45 PM(UTC)
Twistedpair

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I see that my query was based on the incorrect assumption that even after trimming, the Legato's SE output still may have some DC offset drift. I had seen this mentioned (or implied) in various comments on diyaudio. I can't recall all of these, but one such example is here -
http://www.diyaudio.com/forums/digital-line-level/221559-es9018-i2c-controller-11.html#post3238341

Originally Posted by: Brian Donegan Go to Quoted Post
if you are using the Legato's SE outputs, there will be no DC-offset, once the Legato is properly adjusted

Great, that's what I need to know.
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