Whilst researching a preamp purchase (currently using my CD/DAC's digital volume control) I thought, why not consider a build. I've been in contact with Ayon and they confirmed that my CD-5's volume control implementation is digital and 'loses resolution' unless used quite high up in the range (which I don't often do, I tend to listen at the low end of the range). To me it does sound better higher up.
I've never built or tackled any DIY projects, so I thought I'd pitch my plan here and see what you guys think.
Don't really want to open a big discussion on the merits of different volume control solutions, be it potentiometers, R2R ladders, switched-resistor attenuators, ICs, transformer-based designs and whatnot.
For the purposes of my pitch, I've honed in on a design that I think will cover my needs, which are:
1. Relatively affordable - ideally under 10k or so.
2. Compact size - don't have a lot of free rack space left. Plus I just like smaller components.
3. No gain required - between most DACs and power amps there's so much gain going around already.
4. High Quality Sound (of course) - clean, transparent, not lossy like (my) digital volume control.
So. I was intrigued by Pass Labs' use of a relatively new volume IC in their top-of-the-range XP-30 preamp - the model 72320 by JRC. (Also used by NuPrime, AVM, etc.)
"The volume control, also carried on a small daughterboard, is based on a Muses NJU72320 integrated circuit. Although I am an unrecovered collector of datasheets, this chip was new to me; I asked Wayne Colburn about it. "It is part of the NJR Muses line from an in-house audiophile in Japan. They use copper lead frames and laser-trim the part. The designer of these parts came from Japan and gave samples to Nelson and myself to try and they ended up in the XP-30. I run the NJU72320 on ?15 volts so it has a large overload margin. I really like this part as it has no op-amps in it?I only used the front, attenuation section of the chip and not the gain setting section. We didn't use the Muse line op-amp?a discrete circuit is simpler and performs better with higher current and voltage."
(http://www.stereophile.com/content/pass-laboratories-xp-30-line-preamplifier-page-2#x7vBoZg6c62HRrZR.97)
(http://www.theabsolutesound.com/articles/pass-labs-xp-30-reference-line-preamplifier/)
More about the 72320:
http://www.njr.com/MUSES/MUSES72320.html
http://www.njr.com/semicon/PDF/MUSES72320_E.pdf (Datasheet)
I then found two sources for assembled boards - one European,
http://www.akouo.at/select-volume.html
and one American,
http://www.academyaudio.com/volume-control
What do you guys think?
Worth exploring?
I'm quite keen (but will definitely need help).
n
I've never built or tackled any DIY projects, so I thought I'd pitch my plan here and see what you guys think.
Don't really want to open a big discussion on the merits of different volume control solutions, be it potentiometers, R2R ladders, switched-resistor attenuators, ICs, transformer-based designs and whatnot.
For the purposes of my pitch, I've honed in on a design that I think will cover my needs, which are:
1. Relatively affordable - ideally under 10k or so.
2. Compact size - don't have a lot of free rack space left. Plus I just like smaller components.
3. No gain required - between most DACs and power amps there's so much gain going around already.
4. High Quality Sound (of course) - clean, transparent, not lossy like (my) digital volume control.
So. I was intrigued by Pass Labs' use of a relatively new volume IC in their top-of-the-range XP-30 preamp - the model 72320 by JRC. (Also used by NuPrime, AVM, etc.)
"The volume control, also carried on a small daughterboard, is based on a Muses NJU72320 integrated circuit. Although I am an unrecovered collector of datasheets, this chip was new to me; I asked Wayne Colburn about it. "It is part of the NJR Muses line from an in-house audiophile in Japan. They use copper lead frames and laser-trim the part. The designer of these parts came from Japan and gave samples to Nelson and myself to try and they ended up in the XP-30. I run the NJU72320 on ?15 volts so it has a large overload margin. I really like this part as it has no op-amps in it?I only used the front, attenuation section of the chip and not the gain setting section. We didn't use the Muse line op-amp?a discrete circuit is simpler and performs better with higher current and voltage."
(http://www.stereophile.com/content/pass-laboratories-xp-30-line-preamplifier-page-2#x7vBoZg6c62HRrZR.97)
(http://www.theabsolutesound.com/articles/pass-labs-xp-30-reference-line-preamplifier/)
More about the 72320:
http://www.njr.com/MUSES/MUSES72320.html
http://www.njr.com/semicon/PDF/MUSES72320_E.pdf (Datasheet)
I then found two sources for assembled boards - one European,
http://www.akouo.at/select-volume.html
and one American,
http://www.academyaudio.com/volume-control
What do you guys think?
Worth exploring?
I'm quite keen (but will definitely need help).
n
