Passive Volume Control for DACs/Sources

Commercial products are many. Bent Audio "preamp" units (out of production) used a Slagle, and I think these pop up used from time to time. I think they made TVC and AVC products. On the more expensive side, the Emia passive uses it as well. The non-remote controlled Emia isn't too badly priced, actually. The guy that turned me on to Slagleformers was an Emia owner. There are TVC based volume control products also. There's a pretty cheap one from Bangkok that @MrTeaRex has. He said the Emia was only slightly better and (maybe ?) not worth the price delta. I forget what that one is called. There's also Promethius Audio that makes a TVC product. On the (too) expensive side are TVCs by DNA and Music First Audio. Check out Bespoke Audio if you really want a laugh. Probably several others.

BTW, for DIY, if balanced is what you want/need, you can get a balanced Slagleformer. The Emia, for example, is available stereo or balanced. Mine is obviously just a stereo version.

 

I recently switched from using my modded oppo sonica dac with digital volume control back to my cheapo usb dac(sabaj da3) and hattor active preamp with 12db gain and burson v5 opamps.. and it sounds better, more alive and dynamic.. I dunno. This preamp also has 0db and 6db settings I can use. but the 0db is still buffered I think.

 

This is ,another interesting preamp. https://www.tvcpreamp.co.uk/

Tic but includes remote balance etc

 

Don't forget Penny & Giles

 

I have the Django Mini TVC. @JoshMorr and @MrTie have heard it as well. The folks that manufacture the transformers used in the Djangos (SAC Thailand) actually make their own TVC, the Minute Passive Preamp (http://www.sacthailand.com/Amp_PrePassive2.html). I picked up one of these as well and would easily recommend it over a Django as it has all the functionality of the larger Django with a lower price and better build. The photos on the site only show a single ended version, but they make a balanced version if you email them.

 

I like how the web page lists it as the Minuet series of devices yet all the faceplates say Minute. I can't tell if it's a misprint on the faceplate or a typo on the web page, I'd give it 50/50

 

Uuuu, fancy this! Instead of going after Bespoke and their passive vol control I'd give this a go first. Does this little thing make sound leaner&faster in comparison to regular preamps too?

 

Hey @bazelio , I was actually exploring this space when I read your latest adverntures. I was looking at this, http://www.thehornshoppe.com/the_truth_pre_amp.html which is a 'Photentiomer' based circuit, reminiscent of the Melos SHA-1 I think. Its as reasonably priced, with a 30 day money back, so I was wondering if it was worth it, to test?

 

W - If you try it definitely let me know. I've probably read the same material on it that you have. I'd decided to go with Slagle for a couple reasons, but both should out perform a traditional active preamp by a fair amount.

 

How much does this sucker cost? I didn't see a price published anywhere on the site.

 

I got this one Palmer Monicon for $99: https://www.bhphotovideo.com/c/product/1166537-REG/palmer_pmonicon_passive_monitor_controller.html
I am using it as an attenuator, and mute switch between Bryston BHA-1, and two bridged 2B LP. The preamp on BHA-1 is just too hot.Pretty basic stuff but useful.
I read some complains about stereo imaging of Palmer Monicon.I did some listening and crud testing and I do not hear any issues.I checked the position of my speakers, put the same gain on both power amps, and seat in my listening chair with a sound meter and frequency analyzer apps on my phone. I used basic image and channel balance tests from The ultimate test CD. Checked for any channel imbalance with pink noise, scrappers, drums, human voice..between -26dB, -36dB on MONICON. There was none. Then I checked sound stage: human voice 5,10. 30 feet from microphone, 5, 10. 30 right and left from microphone. No difference with and without a MONICON. I listened to some tracks I know very well with and without MONICON. It sounded good.
Not sure if this is conclusive that stereo image is OK but it just sounds right to me.
The knob feels very smooth and solid, the build is very nice.

 

The price for the finished unit was $850 when I purchased one last year. They sell the transformers for $425 a pair and provide wiring instructions if you're inclined to procure the rest of the hardware and solder it yourself.

 

Since we're all making suggestions, I can highly recommend the Tisbury passive pre-amp. £149 for a no-nonsense, transparent (to my cloth ears), 3 input, 2 output (fixed or variable) passive pre-amp. The money is spent in the right place with a decent resistor-stepped attenuator.

I use one to switch between PC & DAC input out to a couple of big headphone amps. Works a treat, looks cute (it's the little brown box, not the enormous black one).

 

I am very happy with my music first audio V2 TVC. I had an Audio GD Master 1 before. Nice class A discrete no negative feedback preamp. Alas it developed a fault in one of the balanced output channels. That was when I figured out that a warranty in China is not worth much, transport to and fro and maybe customs made a repair not a very attractive option. After this experience I wanted a long lasting solution, so I decided against an active solution be it glass or silicon. I thought about the Promitheus but did not like the fact that there was a control per channel and after the Audio GD experience I did not want to buy in Asia. So music first audio sprang to mind, pretty much on the other end of options, no chi-fi but a piece of proper British engineering made on selfmade winding machines by the Engineer himself. At the time I used to listen at very low volume so I ordered one with 36 steps. It took quite some time to get the unit and I was a bit disappointed because it had a quite narrow sweet spot, meaning below a certain attenuation bass was fading fast and the sound became thin. I send the unit back to Jonathan, he said he would like to give it another try and if I did not like it I would get a full refund. He changed the winding and when the unit came back it performed much better. It still has kind of a sweet region, so with volume very low (depending on source level of course) the sound still gets thin but at the right volume it sounds very nice, clear and immediate. Since I have invested in acoustic room treatment I listen at higher levels and I probably would not get the 36 step version anymore but it is a nice piece of gear. Is it pricey? Yes, but then if I call a trained plumber or painter or any other craftsman it will cost around fifty $/h. I don’t know how long it takes Jonathan to wind the transformers and assemble the whole thing I think it is quite fairly priced. It drove my active speakers (47 kOhm) via 7.5 m of balanced cables without any problem from a source with 2 kOhm.
Lately I bought an ADI-2 Pro and I have to admit its digital volume control is so impressive that I am not sure if I still need the music first audio. It still converts SE signals to balanced (and vice versa) and provides galvanic isolation. My speakers have no connection to ground so if I ran the ADI off a battery I would not need the galvanic isolation.
For now I will keep the music first.

 

wow 21.5 feet.. I thought passive preamps had issues with driving long cables? but I guess that's capacitance causing high end rolloff not bass issues.. but still. But yeah digital attenuation is getting better.. I believe some dude just invented lossless digital attenuation.. I think a couple companies just licensed it.. this leedh method https://darko.audio/2018/05/kih-57-a-lead-on-leedh/

 

I have a Bent Audio NOH with silver S&B TX-102 mk3 transformers. Pretty similar with what Music First is offering except the windings are silver. I don't hear this small sweet region you speak off; the whole volume range on my unit sounds good and I only have 23 steps.

I also have a Master-1 preamp, S&B transformers are leaps and bounds ahead of it in performance. Good that you upgraded from that.

 

The capacitance of the cable was rather low 55 pF/m wire to wire and 75 pF/m wire to shielding. Jonathan Billington from music first audio told me that he had a lot of customers using his preamps with long cable runs.

 

Well it all depends, my 31 step (not 36!) preamp has attenuation from 0 to 60 dB, that is quite a lot. When I run my ADI at 13 dBu it delivers 3.46 V. With that setting I am able to go down to 44 dB attenuation without loosing bass, if I go further down the sound gets thin. I do not know the reason for that, it might just be the SPL of around 50 dB this yields at my listening spot calls for some bass and treble boost (loudness correction) the music first audio does not have. It does not bother me as I am not loosing any detail and I do not listen at such low levels anymore. My former DAC had 5 V balanced out, so it was much hotter and then the possibility of more attenuation was more appropriate.
This might just be a lomgwinded way of saying that most people will be fine with the standard version which gives you less than 31 steps.

I'll take your word that the music first audio is much better than the Master 1 I was never able to compare them side by side.