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I can't null DC completely out of one of the outputs (SE or balanced) on my Legato's in my dual mono build. If I adjust the balanced to zero v DC, then I get .25v dc and .30v dc in the R and L SE outs (or 204mV - 220mV). If I adjust both the SE outs to zero DC, I get the DC back in the R and L balanced between + and -. I get the most adjustment out of VR3 and 4, VR1 and 2 don't seem to do much. When I had the single Legato, I had like 8-9v common mode DC between the GND and + or -. There is no common mode DC in my dual mono config. I am using Ventus EZ's for the SE out. They are fed by the LCBPS with its own 30VA transformer. Edited by user Saturday, September 15, 2012 5:26:41 PM(UTC)
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Hi SCR, My dual mono Legato's on my B III's, minus the Ventus for SE are also hard to zero out. I'll let everything warm up and get nice and stable then I can easily adjust either the balanced output dc with the 1&2 trimmers, OR the SE sides and 3&4 trimmers, but then I have to go back and re-zero the balanced or visa-versa. (if that isn't completely confusing). Since I only hook up to SE outs at this point, I zero out the balanced end, then zero the SE (pots 3&4) then call it good. I already know adjusting one throws the other off a little so I just do the above and call it good. I spent a lot of time chasing my tail I think on this before. Everything sounds fine to me. But I'm still learning, all my stuff is still sitting out on a piece of plywood and I'm getting about frustrated enough waiting for a cheaper enclosure, that I might have to break down and buy something more spendy to get it done. The DAC surely deserves a nice enclosure. I'm just paranoid about doing the holes and cut-outs and not botching it all up.  Just have to go slow and take my time. Patience has never been one of my strong points.... /MIke Edited by user Saturday, September 8, 2012 8:04:11 PM(UTC)
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Hi Mike, thanks for providing findings on your dual mono build. Either we both did the same thing wrong or thats the way it is. ;) Like you I am using SE out so I adjusted it to zero DC. I went back at it and adjusted the unused Legato balanced out + and - with VR1 and VR2 to zero, then adjusted the SE out with VR3 and VR4 to zero. The balanced (or Legato R and L SE out) is now .14v DC. Doesn't seem like much; depends on who you ask. When Russ is back I hope he can set us straight. Him and Brain are super smart; I'd love to meet them to see if any would rub off on me. ;) I see the common mode DC between GND and +, GND and - is still ~9v DC. I got zero common mode on the balanced out using R and L SE out so I figured I could use XLR adapters on the balanced out for my SE pre amp. I quickly removed the XLR adapters after seeing the Placid HD BP voltage, which usually is rock steady, jumping all over the place. Yet the sound wasn't dropping out or anything. XLR adapters connect NEG and GND. So another question I have is are XLR adapters a no-no with the dual mono balanced out? If you use the XLR adapters on a single Legato build, you'll put that 9v common mode DC into the pre amp/amp. I went from a single BIII to dual mono and am very impressed with the sound. I think I just knocked my tube CD player off the rack. Chassis wise I like the modushop due to that perforated component panel. Coupled with the well ventilated covers, cooling shouldn't be an issue.  I've also looked at these two places. http://www.hammondmfg.com/dwg25.htmhttp://www.budind.com/chassis.phpEdited by user Sunday, September 9, 2012 12:17:50 AM(UTC)
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1 user thanked Brian Donegan for this useful post.
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Thanks to both of you guys, I've been looking at those
cases. I thought I was going to score a fairly economical
case (~$85 plus shipping) that is very well louvered top and bottom
for air flow. But these things always don't seem to arrive every
month as advertised... I've been looking at those par-metal
cases, too, Brian. Time for me to just do it.
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A friend sent me this link for SiliconRay enclosures. I think they are in China. http://www.siliconray.co...ur/enclosure-chasis.htmlI just went with the Legato's on my dual mono build (no Ventus EZ's for SE out). I was able to null out DC on the balanced out (which are the R and L SE out on the dual build) and use pos and GND for my SE out. All is well! Edited by user Saturday, September 15, 2012 5:24:56 PM(UTC)
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Hi SCR,
That's good to know. I'll try it if I want to hook my dac up to my SE s/s Denon amp.
I guess it's OK to run headphones out at the same time, too? At least with the
balanced - SE deal you are only going one way or the other.
I looked at the siliconray site and many others. There are some beautiful cases /
chassis out there if you aren't too squimish about the price. I've been trying
to go cheap and save the extra dough for more hardware or music software.
If this place I'm waiting on doesn't have my case / chassis later this month as
advertised, I'll probably take Brian's advice and go for par-metal. Looks decent for
the price.
Have a nice weekend!
/Mike
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Hi Mike.
The pos and GND works great for SE out. I actually had to switch to the mV scale on my Fluke meter to measure any DC. I'm not sure about using headphones at the same time. I'd like to add headphones on my SE out, but not sure as the R and L GND would have to be connected to the headphone jack? Maybe Russ or Brian can clear that up.
The VAT really gets you on the modushop cases. CNC and lettering add even more to the price. I may have to sell something to afford a nice chassis....lol
Today is the first time I really listened to music without stressing out over the DC issue. The dynamics and channel separation really stand out with the dual mono build. It was well worth doubling the initial investment.
Rich |
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Hey Rich, I was just thinking of the headphone out connections on the Legato. I would imagine you could use that with either your balanced or SE connected speakers at the same time. Just haven't tried it yet. I sure like that bottom plate in the modushop chassis. They do look very nice. I thought they only charged VAT for sales within the EU? Guess not... This is the cabinet / chassis I was hoping to get that is still relatively cheap, but availability seems to be a problem. http://www.alltronics.co...Panel-Rack-Mount-CabinetI don't want a 19" rack mount box, but I figure I can ditch the handles and the front panel, or at least modify the front panel to work (if I ever get one of these, I'm going to give up if my 2nd 'pre-order' request can't be met). I picked a relatively huge box so I'd have plenty of room to stuff it as I see fit. Sometimes trying to save a little more ends up costing more in money or aggravation or both. Cheers, /Mike
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Originally Posted by: ipa4me 
I thought they only charged VAT for
sales within the EU?
I really don't know for sure......you being right would make it cheaper for me...lol I really like that modushop mounting plate. I would hate to drill that many holes in a flat sheet. A big plus would be if the holes matched up for the TP DAC and PS boards. ; ) I will try and get a standard headphone jack today and give it a try using the SE out. I had some rack mount gear with handles and don't care for the look myself. You could get creative and plug the holes with some nice fasteners or whatever fits and looks good. Keep searching! |
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