With Single Ended Amp, is there any benefit using the Balanced Output from DAC


#1

I just bought a Nelson Pass designed VFET amp. Input is limited to single ended rca’s. From my DAC are there any benefits using the balanced XLR outs combined with an XLR to RCA cable. Typically speaking, are XLR cables better shielded? Or is just using the RCA outs from my DAC the better option?


#2

If the new amp only has single ended inputs there’s no sense in going balanced to single ended. Just use the best RCA cables you can find.


#3

Currently I’m using a pair of Blue Jeans Cable LC-1’s. They claim it’s a highly shielded, very low capacitance cable. This Nelson Pass designed amp sounds very good with the Directstream DAC and these cables. Though it runs much, much hotter than my previous Parasound A21 amp. I just wasn’t sure if any of the inherent strengths found in the balanced out carried over when using a XLR to RCA adapter cable. But I guess it’s all thrown out the window when doing so.


#4

Which one did you get? F6?


#5

It’s a scaled down version of the 40th Anniversary Sony VFET amp he designed and made for the 2014 New York Audio Show. The 6 he made weren’t for sale. He kept 2 and Sony kept the other 4. The output stage uses new-old stock Sony VFETs, which are regarded as some of the best sounding transistors ever made. They were engineered to sound just like triode tubes, but with solid state advantages. But finding genuine ones are extremely hard. The guys over at DIYAudio call them “unobtanium”. Nelson Pass found a stash of them a few years back and others have found some randomly too. Enough to make amps based off of Nelson Pass’s published design. The input stage uses quality Toshiba JEFTs which are also hard to come by.

He designed and released a DIY circuit based on that amp for those interested in making one. Instead of 250 wpc of pure class A output, this scaled down one does 25wpc pure class A but has the same sonic qualities of the more powerful version. I bought mine from someone who built one. Nelson Pass talks about the pros of VFETs here:

http://www.firstwatt.com/pdf/art_sony_vfet_40yr.pdf

And this document talks specifically about the DIY version he designed and published for others to use:

http://www.firstwatt.com/pdf/art_sony_vfet_pt2.pdf

This DIY design inspired him to design and manufacture his own VFET (aka SIT) that’s he’s since used in his aptly named SIT First Watt model amplifiers. Here’s my amp. It’s housed in a First Watt chassis:


#6

I have a J2. I bought it for a second system. My primary system used a hybrid tube amp that I thought I’d never replace. I still have that amp but I almost always prefer the J2. A life long tube-only guy, a ss amp makes no sense sounding this good.


#7

With my single-ended amps I needed the voltage from the balanced output. I use this and it really improved the sound:

http://www.decware.com/newsite/ZBIT.html

Then I moved to a balanced preamp and use the ZBIT to convert the balanced from the preamp to single-ended to the amps. Best sound I’ve ever heard.


#8

I’ve been told by people who’ve heard most of the First Watt amps that mine is like if the J2 and F6 had a baby. Nelson Pass knows what he’s doing. Making a great sounding amp (or any other device) is more of an art than a science. After designing amps for so long he just knows what sounds good and what doesn’t. I haven’t met him, but he seems like a really nice guy too.


#9

Thanks for the tip, I’ll have to look into that.


#10

Well i don’t know what the baby thing means but I can’t imagine you won’t be happy with any of his stuff. I’ve never heard anything with such articulate detail of each instrument in the soundstage, all the while being as warm and sweet as one could want. I chose the J2 over the SIT2 frankly because although the J2 has some feedback, it’s nearly none and it’s fully balanced. Couple with high efficiency speakers and you’re in heaven.


#11

The J2 has a balanced input but single-ended output. Also I’m in love with this GORGEOUS amp.


#12

I think all the First Watt designs are single ended. Nelson Pass doesn’t seem to believe in a balanced amp. The J2 is one of his only “mass production” models which is why I think he added balanced inputs even the though amp itself isn’t a balanced design. Usually he limits most of the models to a production run of 100 amps and that’s it. The amp I have, he only made 10 of IIRC. It’s not even listed on First Watt’s site as I don’t think he considered it a full on model produced.


#13

Are we mixing up SE vs Bal inputs vs SE vs PP topology?


#14

Like Lonson, I too am using the Decware ZBIT to run the balanced outputs out of my DirectStream DAC to the single ended inputs of my amplifier. The sound is no doubt superior when compared to running RCA outs of the DSD.