Passive Volume Control for DACs/Sources

I've always wanted one of these: http://www.ebay.com/itm/171062829201?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT

But Sys was too good a value to pass up - and is presently feeding my first watt F3 clone -> Omega Super 7 mk2 monitors. The Tisbury is prettier and more versatile, but sonically, there are no faults to be found with Sys to my ears.

 

OMFG.

And if I hear even one SBAF member say that they bought this and how great it sounds, then... well then... well... let's just not even contemplate that.

 

Anyone using passive preamps?

Hi all, recently I often came across this point while searching the TVC & AVC on the net: "when the impedance ain't a problem, the good passive preamps are much better than those good active ones in most aspects while the active pres only beat the passive ones in dynamics or bass, but the gaps are far too small to notice."

Guys, how do you think about this?

 

mtoc the whole "more power = more dynamics/bass" is a fallacy that people say disappears when you compare two things after using a mic to perfectly volume match them. it's really just the louder/higher gain active device being at a louder volume total rather than having any sonic advantage. at least that's what I've read objectivists say and passive volume controls since they have no active parts don't have the potential to color the sound the way active preamps do, that's the theory. they can have high frequency rolloff if there's an extreme impedance mismatch though. The other real use active preamps have.. is if your source doesn't have enough voltage output to reach your amps max volume level because the input sensitivity is like 2.5Vrms to reach 100% volume but your dac only gives out 2.0Vrms etc.
I've been trying a few passive preamps and my dacs digital attenuation and honestly I can't hear any disadvantage to the digital attenuation despite mentally knowing it destroys some bits of resolution. Maybe my vi dac just has a really good digital attenuation implementation. It's really nice not having a third device in my chain and not having to use a preamp

 

Nice answer @uncola. A few follow up q's:

I've read about this with passive preamps - some capacitance can build up that acts as a low-pass filter if the impedances mismatch. So in the case of using a Sys in between a DAC and a headphone amp, say a modi2 -> sys- > magni2, what are the impedances involved, and would they be far enough off to be "mismatched"?

My understanding is that all DACS these days operate at 24 bits (or more), so as long as you are using WASAPI, or Windows Mixer with the ouptut set to 24 bit depth, that the digital attenuation should be safe all the way down to like 10% volume or something. I don't know if I trust that, I don't like to go below say 50-60%, so if I am using a sensitive can, I sometime use both a little bit of Sys passive attenuation and a little bit of digital. I should probably pick just one, as I'm probably doubly screwing the signal......

Cheers.

 

Well I think usually they'll say they don't need measurements because what they're discussing is governed by the most basic fundamental theory and it's up to the subjectivists to prove the positive, not them to prove the negative. and then *straw man* *ad hominem* haha I think most people just parrot things they've heard without fully understanding it.

 

Bottom line is the more stages (active or passive) you're chaining together, the more things are going to deteriorate. People should be smart about their gain staging rather than using going overboard with excessive gain and having to use near equal amounts of attenuation.

 

I have a passive pre-amp, partly for it's antique hifi looks and feel (It's a McCormack: quite pricey in its day; makes me feel like an audiophile when the mood takes me) and it has completely passive (works without power) and buffered options.

I hardly dare utter the word impedance, but I do know that, on my pre-amp's passive output, it varies with the volume control, and I suspect that this is why it never sounded good to me through my mid-fi headphone amp and HD600s. Shifted to the buffered output, it gave me an entirely new view of my HD600s, which I had really not appreciated up until then.

The passive output to powered speakers is just fine.

So, depending on what's connected to what, can a passive pre-amp change the sound? yes, it can! And this is a preamp reviewed, in its expensive youth, by Stereophile as being amazingly transparent.

uncola... you know the first rule of hifi salesmen? Louder, if not already too loud, always sounds better. I'd say that the volume control is the cheapest upgrade on any hifi, because an increase in volume can be enough to sound different without appearing, to our perception, louder. Not sure, but I think there is science behind this, and that it is simply loudness curves.

 

I'm making the move to a separate preamp and power amp for my HE-6. (Given my space constraints, the only thing that makes sense is putting a power amp on a small Ikea table under my desk and having a small/medium-pre on my desk for volume control). Setup is going to be Gungnir Multibit > X > Odyssey Stratos Stereo (base model) > BTG audio XLR adapter > HE-6.

I'm currently in a "solve for X situation." This is my first non-integrated power amp or receiver, so I'm extremely unaccustomed to having to shop for a pre-amp separate.

I'll likely use a Schiit Sys in the short term (because it's crazy cheap and crazy small). But any recommendations from people that have heard that chain, own the same chain, or are planning to own the same chain would be much appreciated. Link recommendations to resources that help explain the process would also be extremely helpful. (So far, I've read through this thread and the two main HE-6 threads over at Head-Fi, and the HE-6 threads here & at Changstar).

 

Since the Vali 2 and the Valhalla 2 both have preamp outs, what about using one of them? Would they be like adding a tube preamp/buffer? Also gives you another headphone amp in case you grab a dynamic can again. I was controlling the volume of my Class D amp (and I guess adding some tube goodness) for a while before I added a volume pot. Not on the same level as your setup, but was wondering how they would fit in vs the Sys and some dedicated preamp.

 

Does anybody know of passive preamps with at least one XLR input (for Yggdrasil) that also have a remote control? I haven't found anything that looks cost-effective to fill this need in a combined headphone / video 2.0 setup in a living room.

 

TKD or alps blue at 25$
Goldpoint and khozmo are great choices for 300$.
George lightspeed LDR is 500$ and good option. tortuga is also LDR based and not necessarly better for 800$ then george lightspeed.
for 1k, Bent TVC's are hard to beat price/performance. you also have django TVC.
Ifi Itube is 300$

Im not convinced that something like alps blue or tkd is better then digital attenuation.


the ALPS RK50 would be my choice for price no object but its around 1k. I know a guy who had TVC'S, LDR and prefer the ALPS RK50

 

Yeah, this is the kind of thing that I'm just not sure about just from a lack of experience. I have a Project Starlight III that I'm using as a pre-amp output for my Emotiva 4's (a combination that sounds pretty great). When I used it into my Marantz though (which has a switch to disable the internal preamp), the combination didn't sound very good...and required an oddly high amount of range on the pot (around 3-4 o'clock).

 

I've always wondered this, I use my Mjolnir 2 for preamp outs to LSR305's, but am also about to do exactly what @AustinValentine is trying to do with it, preamp out to a power amp to HE-6.

Do the Schiit amps actually "do things" to the preamp outs (i.e. do tubes/LISST affect the sound) or is it just like a passive preamp system?

 

Valhalla 2 manual:

 

So what would happen if you used the Valhalla 2 preamp out, into a second Valhalla 2 for use as the main amp. So that you effectively have two volume controls, and lots of tubes in the chain. Oh yeah.

 

Thanks, no where in Mjolnir 2 website or manual does it address that, but I'll just assume the same.

 

This is what happens. It's also what happens with chained USB-SPDIF converters and USB decrapifiers.

 

Respect signal fidelity. Fix your problems before the signal even starts.