Passive Volume Control for DACs/Sources

Yes Allegro, I saw that review. It's probably 100% right. Thanks for sharing the review.

I posted on another forum about my friend wanting to sell his Totuga because his Nobsound sounds better, and a Tortuga fan boy attacked me.

 

Honest opinion for those seeking best passive pre: use whatever you currently have (even if its windows mixer) and save up for AVC or TVC.

 

If one does not need a pot, I think the in-line attenuator from Naiant looks like a decent choice for something that is hand made and impedance matched for $20 a channel:

https://naiant.com/studio-electronics-products/inline-devices/mpd-inline-attenuator/

The other over the counter in-line attenuator stuff I found (Shure, AT, Hosa, etc) was more or less for microphone attenuation, which is for low impedance. Basically for an in-line microphone pad where the manufacturer did not supply a switchable pad. There is a Parts Express one that says impedance matching, but I don't see how.

I also don't think the A-Designs ATTY was brought up in this discussions:

http://www.adesignsaudio.com/atty-stereo-attenuator

It is also for line-level attenuation.

Anyway, I think impedance matching is important above all else, pot or no pot.

 

This was my choice too, before I went with the convenience of on-board dac attenuation. Now my fancy TVC is collecting dust. Any takers?

 

Which one do you use?

 

Prism Lyra 1

 

Is it "on-board" digital attenuation or a sepaarate resistor ladder IC?

 

Which TVC do you have? I'd be curious to do more comparisons. Transformer differences can range from minute sidegrades to "WTFOMGEPIKOWNSAUCE". but I daresay that even the entry level ones will outclass resistive or digital attenuation.

 

They get damn pricey too. Bespoke Audio Company should supply a lifetime lackey to turn the damn knob for you.

 

I have been meaning to box up my DIY AMB attenuator which I have had for forever. That thing sounds great and I would not hesitate to use it in a high end speaker setup where the convenience of a remote control outweighs any last bit of transparency that you might get with inductive elements.

The Intact audio AVCs are the best pre amp solution I think folks can readily find. They are reasonably priced and easy (if not a bit tedious) to wire up and build.

I also have a pair of much more expensive Sowter TVCs that I have boxed up. Unfortunately these just don't sound as transparent and dynamic as the Intact AVCs. I'm not sure if it's the TVC/AVC factor, the higher impedance of the Sowters, or just some cursed Brit-fi sauce that they added. And like I said, they are much more expensive.

I have tried other solutions including the Bottlehead Quickie (common cathode) and my own battery powered tube buffer (cathode follower) which are both very respectable solutions albeit not passive. You can tell there's an additional stage added into the sound with active stuff. Even putting an expensive pot (I have Alp RK40 and another metal body one I'm blanking on) standalone just doesn't sound as transparent as you might expect.

Also should add that my Hilo has a Monitor Out which uses a resistor ladder IC to attenuate (with an additional opamp follower inside). Again, not a bad solution but not quite as transparent. I could see the want to control your volume via mouse outweighing any marginal benefit you might get with the magnetic solutions.

 

I have not tried the Goldpoint steppers although I had wanted to. I think Marv told me to steer clear because steppers don't sound as good, but he's getting old and probably sold his HD800 so don't listen to him.

 

Transparent to what? TVC were very colored to me. Less high end dulling than passive resistors but more colored. Still a trade off from what I’ve heard but I haven’t heard an AVC. Seems only popular among tube and horn aficianados.

Prism interface has a built in digital mixer. Mic pres digitally controlled analog steps. Should be better than most of this stuff assuming it’s as good as modern daws and not 1990s Yamaha 02R level.

RME probably has the best solution with a bunch of set analog output levels and digitally controlled intermediary steps. Too bad who cares as the sound is not up to snuff with the best brand stuff but it’s better than what most people have

 

@OJneg I think AVCs (unlike TVCs) cannot be used for balanced to SE conversion, though, because you have a common ground between input and output. Or do I have this all wrong?

 

The Lamm dealer I mentioned use to be partners in Promethius TVC and said it was colored dark. That dealer bought a second Nobsound and in running dual mono, the soundstage got bigger. This is with a two channel system, no head-fi.

 

Dude how much are you getting paid by Nobsound? Lol

Nice tag by the way, I read it initially as “Nobsound Forever” which I actually think is what it should be changed to.

In all seriousness, these are so cheap they’re almost worth buying just for the heck of it, but will wait until @atomicbob at least has a peek at it.

 

My guts tell me you're right. That could explain why I wasn't able to make atomicbob's reverse phase trick work on my gear.

 

Beware that Low volume Chinese manufacturing is very susceptible to counterfeit electrical parts entering the supply chain no matter how good internal qc unless they carefully check every shipment of parts. This cheap crap certainly isn’t as that would raise the cost. Ozarktom’s shill dealer could easily just be selling Alibaba bulk special trash. For all we know Douk Audio, who makes the nob sound brand, is yet another small Chinese manufacturer of audio gear which may or may not use counterfeit parts depending on the unit and production run. “Off brand” or “generic replacement” or straight up counterfeit op-amps, resistors, and caps abound even in popularized brands like AGD. You can figure it out yourself by comparing the marketing hype talk (most high end western manufacturers do not market on part brands) and then looking at internal pics of many brands where the parts do not look like what you can buy from somewhere like mouser. You can also just guess from the retail price and limited volume sold, that the manufacturer isn’t checking every shipment of parts received.

 

You can attenuate a balanced signal with an AVC, but yes, you would lose the benefit of balanced mode transmission. I would not recommend unless you understand the input/output topologies of the connected equipment.

That being said, I might be curious to build a second AVC box with dual channels for balanced attenuation. Have no need currently. Would be interesting to see if the performance holds its ground compared to a similar TVC, which should be much better in CMRR, isolation, etc.

 

Transparent compared to any digital attenuation solution for sure. The Sowter TVC does have an added colouration, similar to what you are trying to describe

 

He's been at it since August last year at least.

"My buddy Rex has replaced his Tortuga passive with this unit" x 1000