Passive Volume Control for DACs/Sources

So if I want khozmo for Gungnir Multibit and some active monitors with 10kOhm impedance, is 10k pot still good or should I request lower?

 

don't think they make lower than 10k pot or stepper

 

Normally you want your attenuator to have at least 1/10th of the impedance of the load (in this case represented by your monitors input impedance)

 

Yeah I read that.. though Goldpoint seems to claim it really doesn't matter. And everyone in pro audio using their 10k pots. Emotiva is also 10k etc..

Crisis averted though. I'll keep using my Audio-GD since I found the random volume problem was previous owners shitty soldering..

 

Well I got a Balanced Khozmo to try anyway, since it was on sale at Audiophonics. A standard 10k caddock version. Using Gungnir Multibit and Eve SC307 monitors, I'm hearing slightly more softer and mushy bass (as it's my favourite bandwidth, needs to be razor sharp and hitting.. well transparent). Quite apparent comparing direct from DAC with software volume control or the NFB-1AMP.

I was really hoping to find something smaller on my desktop than Audio-GD. Wondering if Goldpoint or upgraded Khozmo would help.. but at those prices I think I'd have to bother building it myself.

 

I'm not opposed of digital volume, so perhaps I might get just a high quality XLR pads to drop Gungnir Multibit down from 4V to 2V (EVE's A/D for DSP overloads otherwise). Then get a Griffin Powermate to control the windows master volume. It seems Mutec USB driver captures the master volume regardless whether WASAPI etc is playing, so it's easy to control that way. Not sure if the volume is actually processed on the Mutec side or through Windows stack..

 

I was considering a khozmo at one point, but plan on going with digital attenuation once my new prebuilt soekris desktop dac arrives.. so you saying you prefer digital attenuation is a nice confidence booster for me

 

Anyone has any experience with Burson Audio AB160 XLR Buffer?
The unit here is not passive for sure but what does it do? The seller says it can be used as a passive preamp !?
http://www.canuckaudiomart.com/details/649364726-burson-audio-ab160-xlr-buffer/

 

I think the seller says it can be used *with* a passive preamp.

It is used to correct impedance mismatches between equipment That's about the limit of my understanding.

 

It's an active line stage with no volume control. That is to say, it amplifies a line level signal with no option for attenuation.

It may yield sonic improvements if you have an impedance mismatch or the source (your DAC or phono stage) is not fully capable of driving the load (the amplifier). Probably not though.

 

@wormcycle If you want to try a Burson buffer, I've got their Cable+ buffer thingamabob sitting here. Let me know if you're interested and I'll send it your way.

 

Thanks, I just got confused about this device.What I am looking for is better passive preamp than Nobsound.
http://www.ebay.com/itm/Douk-Audio-...CA-Volume-Controller-/272461238939?rmvSB=true

I am using it with two Nuforce HA-200, which you are very familiar with, but it introduces some noise.
It would not be that bad, I think that the switch from RCA to XLR is messing it up. I would like to bypass the switch but it is almost impossible to open the box without breaking it. I think I will sell it. Thinking about this one https://luminousaudio.com/collections/axiom-ii-passive-preamp/products/axiom-ii-passive-preamp-xlr
But it is way more expensive.

 

rather then Kozmo, id get the hifi collective stepped attenuator. better switch and you can ask them to put much better resistor https://www.hificollective.co.uk/components/stepped_attenuators.html


from Thorsten Loesch advice

"Personally I still found using a Rotary switch and single resistors better than any relay.


http://www.electro-nc.com/rotaryswitchspec.php?id=M7G0148S-75

Some people stock. It will be expensive, but has 48 positions, you need two decks for unbalanced.

This means 46dB in 1dB steps (very fine control) plus a separate switch to add in an extra 20dB attenuation.

This way you get 66dB adjustment range. Use Rohpoint resistors for series resistor(s). Use good quality metal film for all shunt positions, once you find which positions you use most, upgrade those resistors to Rohpoint.

See also here:

http://www.hificollective.co.uk/sites/default/files/hfc_stepped_shunt_resistors_review.pdf

This is about the best attenuator any money can buy, alternative is the TVC but that is a different subject. "

 

I had been looking at the Chinese preamps for that type, but was a bit suspicious of their quality. Thanks for confirming they introduce noise.

I'm now looking at this relay based volume controller for active monitors:

http://www.ebay.co.uk/itm/High-Accu...ced-Potentiometer-Passive-Preamp/253001325754

I posted in the dedicated preamp forum general preamp thread for opinions. Will continue the dicussion there.

 

The noise was present only in the setup with pretty sensitive cans, and Nuforce amps. I used it later between my DAC and Emotiva XPA-2 power amp with both XLR and RCA, and Totem Hawks speakers, and I did not hear any noise. For the price it is a decent build, and for active monitors it should be fine.

 

Recently replaced my EAR 868 tube preamp with a DIY Slagleformer box with input selector. Pretty simple project as Dave makes it straight forward to just solder connections to and from the pre-assembled AVC. It's got a 47-step Elna rotary switch with 1.25 dB per step. The last 4 steps provide gain, so up to 5dB gain. I'm using two sources: DAC and phono right now. In both cases, I rarely go beyond the 15th step - attenuating by 20-30 dB or so. My amp is fairly efficient (I think 28dB), and has a 47k input impedence with 1V sensitivity. This all works out perfectly and obviates the need for an additional active component between the source and the amp.

The change from tubes to AVC had a significant effect on the sound, and I'll never look back now. The two most obvious changes were in bass extension and articulation. Leaps and bounds better, like the 868 just didn't do bass. And I'd cycled through all the memed tubes and tube combinations in that unit. The sound then also became brighter, but in a good way. Stage size increased, notably in the vertical direction. The sound extended much further above the top of the tweeters after removing the active unit. And micro details became more focused, and microdynamics popped.







Easily this has been the single most eye opening audio change I've heard in my system for a long, long time. I had some fun with it, using Front Panel Express, but otherwise this project could be reigned in at just over $1k or so depending on part selection. My chassis came from PAR Metal, switches and knobs from Digikey.

RIP chrome face plate. :-( But as @MrTeaRex will point out, all is not lost. See the chrome plated screw heads used on the front panel side. LOL

 

I looked it up early on (this was many months ago now) and am remembering both sources having OI under 100 ohm. I also measured the output DCR in the AVC at it's midpoint (which is higher than I ever use) at under 2 ohms. What really pushed me in this direction though was testing my phono directly to my amp first. My amp has left right volume control on the back for channel balance. They are very touchy and I always leave them at maximum, but to test, I used them so I could remove the preamp. The rest is history. The AVC is about 95% of direct phono to amp. I used the copper AVC. If you wanted to go crazy, the silver AVC might get you to 97%. The guy who turned me on to the Slagle in the first place said the silver is ever so slightly better.

 

On a more basic note, if you have enough gain in your system and are looking for balanced, passive volume control check out the Mackie Big Knob Passive. It has dual switchable TRS inputs/outputs, mono, mute and dim controls and goes for a whopping 70 bucks.

Yes, at this price it does use a pot (I'm not sure what kind) but it's a smooth operator and level matching is tight at all but the first few degrees of rotation, which is scarcely audible.

Most importantly it's quite transparent; when I was previously using my audio interface's monitor controller I tried switching over to line output via the Big Knob and the improvement to soundstage depth was immediately apparent. I'm currently running it between my Gungnir Multibit's balanced output and my Adam A5X/Sub8 with great results, and at some point in the future plan to make use to the second set out outputs with an addition pair of speakers.

Eventually I'd like to get a passive stepped relay attenuator, bit it will likely be unbalanced and lots more expensive so I'm more than happy to stick with this for the time being.

 

This is an interesting topic for me. I only have a single source (Gungnir Multibit, fed by an NAA streamer) and have been looking for the most transparent preamp/VC possible. Right now I'm using Saga for this purpose, and find it to be pretty transparent, but wondering if there is better considering I really don't need the source selection. I would prefer to have remote volume capability as well if possible for my lazy ass, but would entertain one without if it was exceptional sounding.

AVC (autoformer vol ctrl) looks extremely promising, but the commercial products I've seen using them are extremely expensive (especially with remote volume ctrl) and my DIY skills to make my own are nonexistent.

@bazelio have you seen any commercial AVC products worth a look that won't break the bank?

One thing I admit is that I do sometimes enjoy the slight amount of tube coloration (soundstage expansion, more present vocals) that I can add with the single 6SN7 in Saga (as long as it's a good one, like Sylvania VT-231) but wondering if a really transparent volume ctrl would take that need away.

Edit: Should have said, I'm looking to feed a single Vidar.

 

It seems ill be getting a ALPS RK50 for my AN kits el84 l1 amp!