[pgastone]

Hello Morten and other Tortuga fans!

For many months now I am been wracking my brains for a preamplifier upgrade- currently I am using a PrimaLuna Dialogue premium and that is driving a pair of Pass Labs Xa 60.5 mono's.  The speaker are Thiel 3.7's and the source is a Monn 280d DAC.  Cables are all Nordost Heimdall.  I listen almost predominantly to Tidal but plan to add Qobuz as well. 
The system sounds very good but I would like to add more depth to the soundstage.  Ultimately I think I can only get there with a greater  degree of transparency to better capture the spacial clues of the recording and the instrument texture and decay.  The width of the soundstage is very good and the speakers virtually disappear but now I am trying to achieve better 3D dimensionality.  I think a preamp upgrade is probably the next important step towards my goal.  I think the PrimaLuna, though quite good,  is not quite up to the task- for one it uses alps blue velvet pot which I think may be part if the issue.  The parts are generally high quality but of course some compromises have to bad to build the unit the the targeted price point.

I have been doing a lot of research but so far had only been considering active preamps- the short list was a Pass preamp for possible system synergy, a PS Audio BHK as a hybrid alternative, or an LTA MZ3.  But now I have started looking into passive and/or buffered alternatives which has started to really intrigue me and which brings me here.  The Tortuga seems like an amazing product.

My first concern is whether a passive would be a good match in a system like this: Pass labs only have a 30k impedance (single ended) and the speakers are anything but an easy load- impedance drops to 2.5 ohms for considerable part of the frequency range.  The DAC has a 2v output.

Anyway, I thought I would ask for your expert opinions on whether you think this solution would be feasible and take me to where I am trying to go with my system.

Many thanks!

[tortugaranger]

Hello Morten and other Tortuga fans!

For many months now I am been wracking my brains for a preamplifier upgrade- currently I am using a PrimaLuna Dialogue premium and that is driving a pair of Pass Labs Xa 60.5 mono's.  The speaker are Thiel 3.7's and the source is a Monn 280d DAC.  Cables are all Nordost Heimdall.  I listen almost predominantly to Tidal but plan to add Qobuz as well. 
The system sounds very good but I would like to add more depth to the soundstage.  Ultimately I think I can only get there with a greater  degree of transparency to better capture the spacial clues of the recording and the instrument texture and decay.  The width of the soundstage is very good and the speakers virtually disappear but now I am trying to achieve better 3D dimensionality.  I think a preamp upgrade is probably the next important step towards my goal.  I think the PrimaLuna, though quite good,  is not quite up to the task- for one it uses alps blue velvet pot which I think may be part if the issue.  The parts are generally high quality but of course some compromises have to bad to build the unit the the targeted price point.

I have been doing a lot of research but so far had only been considering active preamps- the short list was a Pass preamp for possible system synergy, a PS Audio BHK as a hybrid alternative, or an LTA MZ3.  But now I have started looking into passive and/or buffered alternatives which has started to really intrigue me and which brings me here.  The Tortuga seems like an amazing product.

My first concern is whether a passive would be a good match in a system like this: Pass labs only have a 30k impedance (single ended) and the speakers are anything but an easy load- impedance drops to 2.5 ohms for considerable part of the frequency range.  The DAC has a 2v output.

Anyway, I thought I would ask for your expert opinions on whether you think this solution would be feasible and take me to where I am trying to go with my system.

Many thanks!

Your DAC has an output impedance of 100R so chances are quite good that a passive preamp will work well with your 30k amps. At the default 20k  impedance setting of our passive preamps you'd end up with 20*30/(20+30) = 12k effective impedance as seen by your DAC. That would give you a 12,000/100 or 120:1 bridging ratio which is well above the 50:1 guidance. So in short, it's doubtful that impedance matching would be an issue here.

It's extremely unlikely that the lack of gain in a passive preamp will be a limiting factor in terms of volume headroom. The only clear instances of where our passives could not provide adequate volume headroom has been with flea-watt tube amps driving less than super efficient speakers - those cases needed actual gain in the preamp.

In my view the biggest variable that determines how satisfying a passive preamp will perform in a given system is the robustness (current drive capacity) of the output stage of your source/DAC. That's not something you can discern from specs. Better  source  gear (better designed, usually more  expensive) source gear will generally perform better with passives but that's arguably an overly broad generalization.

In the  end you just have to try it. We offer a no risk 30 day in-home audition as part of our buy-try-decide policy. You have 30 days from receipt of the equipment to decide if it suits your needs. 100% refund less your cost to ship it back if you're not happy for any reason.

Cheers,
Morten

[pgastone]

Many thanks Morten- yes I should have mentioned that the other concern is the power supply of the dac.  Pardon my ignroance as this one area I am less familiar with but would buffering help address this issue?

I understand you are working on an all in one solution combining your tube buffer and passive in one unit?  Also, in the past you made an all in one with mosfet (LDR300) and you were also looking to come up with a new version.

Just thinking this through, considering how competitively priced your passives are (i only use single ended) I conceivably could think about upgrading the DAC  too to get to the right results.

[kernelbob]

Hi pgastone.

I've been using a Tortuga LDRxB controller (the balanced version) for several years now in a bi-amplified system.  I'm running Lampizator True Balanced 211 Monoblock amps on top and a pair of Spectron Musician III amps as monoblock amps on the bass. That's asking a lot for the LDRxB to drive.  The Lampis have 200 kohm input impedance (100k per phase per channel).  The Spectrons in monoblock mode have 25 kohm input impedance per phase.  Additionally, my DAC has fairly high output impedance.

That's asking a lot for the LDRxB to drive given that the amps' input impedance is in parallel.  I've recently added the Tortuga Tube Buffer ahead of my bass amps.  As good as the system sounded before, inserting the buffer just in front of the bass amps improved the sound from the bass to the treble with greater harmonic complexity and better dynamics.

I've compared the Tortuga with several highly regarded preamps which all cost more (much more in many cases).  Without exception, the Tortuga clearly exposed those preamps' faults.  The challenge for the Tortuga controller is that many people have low expectations on any passive controller.  I urge you to give the Tortuga an audition in your system.  Given that your Pass amps (those are some fine amps!) have a low input impedance.  An audition of the Tube Buffer should be on your short list at some point to see how the total system can sound.

Regards,
Robert

[ssglx]

Just wanted to add my 2 cents.
I just finished a listening session after cleaning the cabling and installing my summer setup; replacing my tube preamp with the Tortuga, and installing my larger bookshelf speakers. I must say it sounds electrifying!
I had tried several passives before I put a demo Tortuga in the system, and the difference was immediate. Transparent AND warm and fleshy with excellent bass.

I would try a Tortuga with no buffer first. If it plays nice with your other gear and sounds great, I would stop there.

My system is decidedly mid-range, but after 50 years in this hobby it sounds as good to me with music as about anything I've heard.
Musical Fidelity V-90 dac
Tortuga LDR3.V2
Monarchy SM-70 Pro Amplifier

Chris

[kernelbob]

Hi smilax.

"Transparent AND warm and fleshy with excellent bass" is also a perfect summary of my experience with the Tortuga.  I was especially surprised with the bass.  It's actually better than any other controller/preamp I've tried.

In the subject system using amps of 20 kohm input impedance, I do think the tube buffer is worth a listen.  I resisted auditioning one too long in the name of keeping the signal path as simple as possible, "first do no harm".  However, the improvement in realism when I did finally try it, was obvious from the first few seconds.

Regards,
Robert

[pgastone]

Thank you very much for your replies.
I think I am going to have to try the Tortuga- it sound very compelling indeed.  I think that as Chris suggests I will probably try to run pure passive and then try buffered.  I will speak to Morten>
Out of curiosity does anyone have a view of the differences between the tube buffer and the solid state buffer that was included in the now discontinued LDR300?

I think the tube buffer would be something I would adapt more easily as I do have a tube preamp now.  But then again I have heard some spectacular solid state preamps and I doubt I would miss tubes in the sound chain.

Robert, I was wondering if you could tell me what active preamps you compared and also what your current speakers are- you seem to have a spectacular system.

[kernelbob]

Hi pgastone.

I edited my previous post to clarify that I was referring to the tube buffer with my second paragraph.  Regarding the buffer, I'm using it with 6H30PI tubes.  They sound neutral, doing nothing other than their job, which is to provide a high input impedance facing the Tortuga controller and a very low output impedance facing the power amp.  Their job is not to add a euphonic "tube" sound to the system, but just to optimize components impedance interaction.  Colorations, tube or solid state, over time show themselves to be deviations from realism.

I initially compared the Tortuga LDRxB against my Audio Research REF3.  The Tortuga bettered the REF3 in every respect.  Since then, I compared the Tortuga with a variety of preamps, some costing five figures.  None could equal it.

I'm using the VonSchweikert VR100XS speaker system.  Mine have the Ultra upgrade with MasterBuilt Ultra internal wiring and internal crossover component optimization voiced by Albert.  I also use MasterBuilt Ultra cabling.  My DAC is the Lampizator Pacific.  By the way, it likes the Tortuga input impedance set to between 85 and 91 kohms per phase.  I vary the input impedance (using the remote) depending on the recording characteristics.

Regards,
Robert

[RDavidson]

Get that decked out Tortuga unit with the jfet buffer, currently in the Trading Post, and don't look back. 

[glynnw]

I believe Morten mentioned in one of his upcoming products updates here that they found the tube unit to sound better and what they would concentrate on in the future.

[Tubeburner]

Morten said he could only afford to develop so many preamps, so he is building the tube buffered JFet and discontinued the LDR300.25. I have owned the passive and the 300v25. I use a tube dac and tube mono blocks, so adding a tube buffer doesn't serve  a purpose IMO.  Morten's demo was with pro audio solid state amps, so the tube buffer may have helped there along with the room correction he used. Like most, it will be system dependent.  The 300v25 added dynamics that the passive did not deliver, IMO.

[RDavidson]

The tube buffer is primarily for impedance matching and drive...not necessarily for the purpose of adding "tubiness." I have a custom built Tortuga unit with an Aikido tube buffer, perhaps the inspiration behind Morten's latest work , and it is very transparent and tonally natural without being overtly tubey. It works well with both SS and tube amps. I am not surprised Morten is chosing to focus on his tube buffered preamp. I'm sure the jfet buffered version is also excellent and maybe even more perceptively linear. But let's face it, tubes are just cooler and more fun...especially when they don't cost a fortune to roll.

[tortugaranger]

While the solid state JFET buffer used in the LDR300 does indeed add some drive and improved dynamics when used with source components that can benefit from a stronger buffer/drive stage, the tube buffer goes a step further opening up and revealing more detail and subtlety in the music while using essentially the same JFET buffer output stage used in the LDR300 but with the addition of the tube input/gain stage. It's more than simply layering in some tube euphonics ("tubiness" if you will), adding the tube clearly raises the bar on the overall sound quality. The 6H30 tubes are very clean and neutral. Various 6922 tubes can add a more lush tone which some will find pleasing. Roll on.

[Tubeburner]

Morten, will there be an upgrade path for owners of the 300v25? Since many of the parts are the same, a new case and the additional tube buffer circuit could be an upgrade path once the new design is done?

[tortugaranger]

Morten, will there be an upgrade path for owners of the 300v25? Since many of the parts are the same, a new case and the additional tube buffer circuit could be an upgrade path once the new design is done?

While the core of the JFET buffer design is schematically similar for both types of preamps there are only a few discrete parts involved in common that would have to be successfully de-soldered from one and installed in the other. There's really no fundamental benefit or savings involved were we to try to do that. It would be like selling someone a new car but using the steering wheel and brake rotors from buyer's existing car. Sure, you could do it, but it wouldn't be worth it. Said another way, the overall design/layout of the tube buffer is very different from the solid state buffer and one can't  be dropped into the other as a compatible module.  There's more value in an LDR300 as an intact functioning preamp than scavenging the few parts which might even get damaged in the process.

[Mjw21a]

Darn... You've got me looking at the LDR3000x.V3 Tube Active with CuTF cap upgrades on your site and I haven't even received my new LDR300x V3 Active yet. I may start a savings fund towards one of these. Love the bamboo sides. Just stunning.

Mind you I'm unsure if my system would benefit my Abbas Audio DAC 2.2SE has a tube output stage also?