Have Passive Preamps Finally Come of Age?


Back in the late 90s (eons ago) I tried a variety of passive preamps (PPs). The most musical was an autoformer, but back then my system was not balanced. For the last decade I have been using active preamps, both tube and solid state, but finding a quality balanced preamp under $4K is damn near impossible. Enter the Parasound P5 (2.1), which in addition to having balanced I/Os, it has a separate bass management circuit (MSRP $1095), and I was hoping it would provide better control over the built in class D plates incorporated into my 2 SVS powered subs, whose volume controls are STUPIDLY sensitive: when barely cracked from zero they overwhelm. Alas, no bueno. 

Recently i watched a PS Audio YT video that was emphatic about NOT connecting powered subs with interconnects; instead he recommends speaker cables piggybacked off the main systems amp/s. I had a spare set of DIY flat copper cables, and was shocked how much better they sounded, but doing so did not change the  volume control problem and unfortunately this id not bypass the SVS amps whose class D chips are now ancient. Thinking there could be an impedance problem led me to revisit PPs.

I sold my P5 and was using the XLR outs from my Oppo 105 (upgraded power supply and IEC/wiring to the power supply) direct to my Emerald Physics 100.2SEs (class D). The noise floor dropped tremendously, allowing me a much better view into the music. My Core Power Technologies 1800 PLC had more than a little to do with this, but...  

Days of PP research later, I came across LDRs, which seem like the ultimate PP option, but XLR versions are ~ $2K and up, with the Tortuga coming in at $2700, seems like a true SOTA bargain, just not in my current budget. Scouring the' for sale' sites I came across a Hattor XLR (MSRP $995) which was in my price range. Hattor's www had links to 2 reviews both were extremely positive: one used it in combination with a class D amp. Bingo! I snapped it up.

It arrived late yesterday, although Hattor's www pictures look awesome, they do not compare to seeing and touching it. The metal carrying case was an indication of the designer's dedication. This is an etremely well made piece of kit, but how does it sound? Alas it came with no manual and Hattor's site does not have a PDF. How hard can it be to hook up? Well, after a couple scary minutes, I discovered that it would not light up until I connected the 105. 

Stone cold, the first thing that shocked me was a further reduction in noise floor and an incredibly wide and deep sound stage, but as can be expected, it was dry. Fingers crossed, in about a half hour I began to be rewarded with texture as well. Tis only got better as the night wore on

I hope somebody chimes in with their Tortuga experience, or any other high quality PP information.that goes under the reporting radar. 
tweak1
Well, it seems to me the gain issue ( voltage ) has just be proven by kosst's last post, taken from Nelson Pass himself. Take care of the impedance issue, using buffers ( 0 gain ) and the source can drive most power amps quite well. Enjoy ! MrD.
Well, it seems to me the gain issue ( voltage ) has just be proven by kosst's last post, taken from Nelson Pass himself. Take care of the impedance issue, using buffers ( 0 gain ) and the source can drive most power amps quite well. Enjoy ! MrD.
This is certainly true- if your only source is digital. If other sources are involved (such as a tuner, tape or phono) then it won't be the case. We've built buffer-only preamps for some of our customers that are digital only, but at least one of those shipped his preamp back after about 5 years and had us install the active gain circuitry as well, despite all his sources being digital. If you have more than one source, occasionally you run into the issue that not all digital sources actually conform to RedBook output standards. These sources will need additional gain. 

The thing is, if you do your design homework, the distortion and bandwidth limits of the active line stage can be much better than those of the source itself and if you do your engineering homework, its possible to insure that the kinds of distortion it does make are of the type to which the ear isn't particularly sensitive.
I have run 3 different dacs, 4 different tuners, a Samsung cable box, and a laptop from it’s headphone jack, through the passive, all with excellent results. I have also used 4 of my power amps, again, all with excellent results. If I am listening to distortions, so be it. It betters the preamps in detail, transparency, and neutrality.  Enjoy ! MrD.
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mrdecibel
I have run 3 different dacs, 4 different tuners, a Samsung cable box, and a laptop from it’s headphone jack, through the passive, all with excellent results. I have also used 4 of my power amps, again, all with excellent results. If I am listening to distortions, so be it. It betters the preamps in detail, transparency, and neutrality. Enjoy ! MrD.

You hit the nail on the head MrD with that proof. The others above are just in product protection mode.
RK I suggest you don’t align yourself with the your new yes man, it won’t be healthy for you in the long run.

mrdecibel
Take care of the impedance issue, using buffers ( 0 gain ) and the source can drive most power amps quite well.
Yes it’s true, those impedance issues hardly raise their heads these days,
that’s why passive are the way to go, buffers are the next choice if there’s impedance issues.

tweak1
"Have Passive Preamps Finally Come of Age?"
Yes they have, and it’s more to do with what’s the sources are doing now that make them the preferred volume control choice, because today sources are low output impedance, have higher output voltage, are mostly dc coupled, and their output stages are as good if not better that many active preamps especially tube ones 

The only way of getting better sound than a passive this is to go direct from source to poweramp if the source has it’s own digital domain volume control that can be use in it’s top 25% so it doesn’t "bit strip".

Cheers George