# My Review of the Tortuga Audio Passive Preamp



## konut

This is part 1 of a review of the Tortuga Audio LDR1 passive volume control, or passive preamp, as some like to call it.

http://www.tortugaaudio.com/

     There was a delay in getting a newly implemented control software chip due to refinements that were required after beta testing. Part 2 will consist of a comparison between the original chip and the new chip. I felt compelled to post my thoughts while they were fresh in, what little is left of, my mind.  
      My system consists of a Sony BDP S580 BluRay player hooked up via a 15ft length of DH Labs SilverSonic D75 coax BNC/RCA adapter->BNC to a Bryston BDA-1 DAC(Mojo Audio PC). The single ended out then goes to Creek OBH-12 passive pre via a 26" pair of Sweet Spot Reveal "Silver" interconnects then from the Creek to a pair of W4S SX500 mono amps(W4S P-1 PCs) via a 3ft pair of Grover Huffman ICs. A 3ft pair of Anti-Cables go from the amps to Aether Audio Black Boxes, Aether Audio Timepiece Minis and VMPS Super tweeters(facing backwards). The amps are plugged into the wall, and eveything else in plugged into an APC S15 power conditioner and Belkin PureAV PF60.The LDR1 replaces the Creek.
           I have not used an active pre in almost 20 years. My system is optimized for use with a passive pre. The Bryston DAC was selected because of its 2.3V, 50ohm, discrete analog output, and reliability. The W4S amps were chosen for their high gain, low noise and distortion, and relatively high, for ICE power  type amps, input impedance of 60k ohms. ICs are short and low capacitance. No accommodations were made to substitute the Creek with the Tortuga.
        I've been on the hunt for a replacement for the Creek for some time. To be sure, the Creek is an entry level passive but offers 3 input switching and remote so it met my needs. The replacements that I have considered over the years all have some perceived weakness. Mostly they offered no, to me, significant increase in sound quality commensurate with their price. AFAIK, there are only 3 methods of implementing passive pres; resisters, transformers, and light dependent resisters. Each method has its assets and liabilities. It wasn't until the Tortuga came along that I felt there was something that minimized the minuses and maximized the pluses and justified the asking price. I jumped at the opportunity to secure a spot on the audition tour that was offered.  
      I received the unit on Halloween. Trick or treat? It is housed in a nondescript black case with a window for the infrared remote receiver, blue lettering, a black knurled knob, and an on/off blue LED that some might find too bright. After substituting the LDR1 for the Creek I got no sound. I called Morten to see what could possibly be wrong. He indicated that there was not much that could go wrong. When installing the unit I had double checked that I had made the correct input/output connections, as I have made that mistake in the past. While on the phone it occurred to me that maybe I had forgotten to turn my amps back on. That, indeed, was the case. How embarrassing. I had a nice chat with Morten, indicated all was well, and he could not have been more cordial. I had tricked myself and now for the treat.
          It became immediately apparent that the LDR1 was a more transparent component than the Creek. At 3 times the price, one should expect that. What they had in common was the black background, low/no distortion, and wide sound stage. The LDR1 improves on the Creek in a number of different areas.
           Leading edge attack transients are more delineated throughout the frequency range. This was most noticeable with all types of percussion. Snare, cymbals, toms, and kick had much more snap and precision.
         The mid-bass on down seemed to gain a few extra db of authority. Not lumpy mind you, but a smooth fullness contributing a sense of realism to whatever instrument was in that range. The extra degree of sub 40hz info gave an increased sense of acoustic space.
       Low level detail increased to a great degree. Previously obscured detail was laid bare. Each instrument and voice gained, not only an extra dimension in space but, resolution giving a sense of the artists emotional intent.
       It seemed like the LDR1 was letting more signal through. I was listening at levels above my usual, 85db-95db, to levels of 100bd+  as everything just sounded so good. Some discs which I had been able to turn up all the way with the Creek, and in theory should be the same as a bypass, were needed to be restrained a bit as not to push the amps, and/or speakers, past their limits.
       There was a greater sense of dynamics, compered to the Creek, at all volume levels. Greatly anticipating the new chip to see if this is expanded.
      If I were to change anything I would give some sense of the volume going up and down other than just the aural evidence. As it is the blue LED flashes slowly when either the volume is all the way up, or all the way down. There is an enter button on the remote which causes the LED to flash rapidly and I would prefer this sense of feedback when raising and lowering the volume. This is the way the Creek works but this is by no means a deal breaker for me. I would also like a less bright LED, but, again, not a deal breaker.
      I listen to a wide variety of music. I pulled out discs that I had not listened to in years and probably listened to more music, since receiving the LDR1, than I had listened to in the past 6 months. I was given a renewed sense of excitement that I had been missing for a long time. I can't think of higher praise. As a casualty of the part-time economy I shall have to find a way to acquire one of these.


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## konut

This is part 2 of a review for the Tortuga Audio LDR1 passive preamp. I was able to audition the LDR1 for a full month before receiving the updated software chip. There had been a delay in sending out the chip as it was discovered there were certain anomalies with Class D amps. Once those were resolved the chip was sent out. Since I have W4S Class D amps, it was reassuring that this was checked out. Having the LDR1 for so long made it easy to hear the difference between the old software and the new software.
     The only difference in actual operation of the pre was that now when the volume was raised or lowered, the LED fast flickers. Tortuga had incorporated my suggestion. Nice! 
     The purpose of the new software was to increase and optimize the input impedance thus resulting in better dynamics especially at lower volumes. In actual practice it did much more than that. Dynamically there was a sense of  increased transient response though not nearly as significant as the difference between my old passive and the old software. At lower volumes it was difficult for me to detect a significant increase in dynamics across the board. What was significant was a marked increase in low level detail, even at lower volumes. But the most improvement came in rendition of sound stage. At all volumes there was an expansion of width and depth as well as a greater perception of space. There was a smoothness to the presentation that gives a greater sense of reality, especially in live recordings. 
      My GUESS as to whats going on is that the precision of the channel balance that the original software pioneered is further enhanced and made more apparent by the impedance optimization. Those spacial cues that are embedded in the phase relationships are made more precise by the channel matching and brought to the fore by the impedance refinement. Again, just a guess on my part.
     Having sent the unit on to the next participant on the tour, and going back to my previous pre, I noticed that the texture of instruments and voices are less refined. The subtle emotional nuances are less. There is a flattening of the sound stage and the sound sticking more to the speakers. Harrumph.
     Having worked in live sound for a few years and maintaining an interest in audio as a hobby for 40 years, I have come to appreciate that everyone comes to different conclusions as to what they hear and thus how they want their audio to be reproduced. Its a trial and error process hopefully with correlations between what is heard and what can be measured. That has been my experience anyway. What I have found is that low distortion, high signal to noise ratio, and flat frequency response are the preeminent determinants as to whether I will like a certain component. Others have come to different conclusions. 
       The very nature of the recording process manipulates the sound running it through various circuits with all kinds of deleterious as well as beneficial effects, some recordings more than others. Some are of the opinion that since this is the case why not use every means at our disposal to manipulate the sound, when reproducing, to achieve pleasing results. Those that use passive preamps take an opposing view. The last thing we want to do is use anything that will obscure the waveform as its delivered by the source medium. The fewer circuits the better. While I have not personally auditioned a lot of passive pres, I can say that the LDR1 is as a transparent component as I have ever encountered. I will be curious of the findings of the rest of the tour participants as to how the LDR1 performs with their systems. Thanks to Tortuga for sponsoring the tour.
       The LDR1 tour is a being conducted for members of the Audiocircle forum who responded to a thread in the Tortuga Audio sub-forum. You can follow it here.
 http://www.audiocircle.com/index.php?topic=119915.0


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## rsbrsvp

I have an LDR-1 and it is fabulous.  Best preamp I ever owned at any price.   When I bought it I thought I would get super transparent sound at the cost of thinning things out. Usually, that is the price for transparency.  I took the risk anyway.   I was dead wrong.   The transparency is indeed the best I ever heard- but it is so full sounding- I can't believe my ears.   Now- warm and full are not the same.  It is not warm. It is truthful to the recording.  Regardless, it is that fullness and weight and supreme smoothness without sounding bloated and without giving up one iota of detail which makes this a world class product.  I doubt things could get more than 5% better at any price- even $100,000.  The LDR1 is the most perfect preamp I could ever imagine.


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## brunk

rsbrsvp said:


> I have an LDR-1 and it is fabulous.  Best preamp I ever owned at any price.   When I bought it I thought I would get super transparent sound at the cost of thinning things out. Usually, that is the price for transparency.  I took the risk anyway.   I was dead wrong.   The transparency is indeed the best I ever heard- but it is so full sounding- I can't believe my ears.   Now- warm and full are not the same.  It is not warm. It is truthful to the recording.  Regardless, it is that fullness and weight and supreme smoothness without sounding bloated and without giving up one iota of detail which makes this a world class product.  I doubt things could get more than 5% better at any price- even $100,000.  The LDR1 is the most perfect preamp I could ever imagine.


 
 I agree, I've had the LDR3x since summer of 2013 and can echo your impressions.


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## exdmd (Jan 8, 2019)

The THD and IMD of the Tortuga LDR3 passive preamplifier has been measured. At normal listening levels THD+N measures about 1% (!) ...  unacceptably high for a modern preamplifier. I auditioned an LDR3 and a Schiit Saga at the same time. The sound of the Tortuga was colored and not as transparent as the Saga. I sent the Tortuga back for a refund and kept the Saga.


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