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

Showing 6 responses by mitch2

One way to find out which you like better (i.e., pure passive or passive with an active buffer circuit) would be to purchase the Hattor or Tortuga passive and then add their buffer.  Tortuga offers a 30-day return policy in the event you like the sound better without the buffer.
Tortuga does offer a tubed buffer. I tried it on their "tour" and it sounded pretty good. My Goldpoint passive along with the Tortuga buffer did not quite equal my SMc Audio unity gain buffered preamp, but the SMc piece is much more expensive.

From Tortuga Audio
Our 30 day audition policy provides you a nominal 30 day window to audition any Tortuga Audio product. If you are not satisfied with your Tortuga Audio product just return it within 30 days of receipt of the shipment and we will refund the full purchase price. No questions asked.

@atmasphere 
FWIW dept: our MP-3 preamp can be ordered as a balanced tube buffer with no active gain stage.
That is interesting Ralph, I wish I had heard the no-gain version back when - I may not have sold my MP-3.   Now I have a great sounding SS unity-gain buffer by Steve McCormack so don’t have the need for another.  You should get the word out.  With today’s high output DACs, that might be just the ticket for many.

@celander 
This back and forth is hilarious.
I mostly agree.  For example, what does "finally come of age" mean? 

The Hattor is simply a resistor based passive volume control, not unlike Goldpoint, Placette, and others that have come before, and not really unlike what is in Ralph's preamps except that those also provide buffering and gain. 

George wants us to believe the Lightspeed is "compatible" with most impedance and gain situations - and that may be true.  However, just because something is "compatible" doesn't mean it is the best-sounding option. 

What's missing is that this is really about what one hears in their own system.  If a listener likes the sound of a certain type of passive in their system, then that's what matters.  If they want to compare their passive with an active circuit, then they can simply connect a buffer to the passive and decide which sounds better.  There are many on this site who enjoy the sound of their passive volume controls and many others who prefer their active preamps or buffers.  There are other options such as DACs by Empirical Audio and Metrum Acoustics that adjust volume by changing the reference voltage, which does not negatively affect the signal like DACs that throw away bits of information to reduce the volume level.  This is really easy, try several options and stick with what you like best.
I auditioned their tubed buffer when it was on "tour" and thought it sounded pretty good for the price when in line with two different passives I have here (both resistor based).  I am a little surprised they are not offering both tubed and JFET buffer sections in the active preamp since they already have the tubed buffer designed.  I suspect the preamp will represent a relatively high value for a modest price.
I just purchased Metrum’s Adagio (for the second time).  It has a volume control implemented by changing the reference voltage in the DAC, so it is like having a volume control that is not in the signal path.  
In my previous direct comparison with their Pavane Level 3 (essentially the Adagio without volume control) my McCormack unity-gain buffered linestage with the Pavane added a touch of body and tonal density that seemed just out of reach of the Adagio used DAC-direct to the amps.
i really wanted to simplify my system this time around by going DAC-direct but may try something different since I was recently given instructions on how to easily remove the (high-quality Shallco) volume control from the linestage’s circuit to make it a very high-quality unity-gain buffer.  Running the Adagio through the buffer will hopefully give me the best of both approaches.