New LDR6 Passive Preamp using light dependent resistors

[CaptainWatt]

Hello out there.
Wanted to introduce ourselves and let you know about our new LDR6 Passive Preamp. Six line stage inputs. Digitally controlled analog LDRs. Comes with remote but also fully controllable via single multi-function encoder knob. Sounds wonderful because LDRs just do.
Check it out.
Questions/inquiries welcome.
Cheers,
Morten
Tortuga Audio - Handcrafted audio gear for music lovers

 

[CaptainWatt]

Hi All!!

We've received inquiries regarding future plans to offer our passive preamp with only a single input and perhaps 2 or even 3 outputs.

We'd be delighted to hear from you on what configuration/features you feel would be most desirable.

Fire away!!

Cheers,

Morten
Tortuga Audio - Handcrafted audio gear for music lovers

 

[CaptainWatt]

Single Input LDR1 Passive Preamplifier Coming Soon!

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We've completed the design work on the LDR1 version of our Passive Preamplifier. Here are engineering/artwork pics of the new front/rear panels. The LDR1 will have a single input and dual outputs. Otherwise the same functionality as the LDR6. Hope to have panels from the fabricators by mid-November so we can start delivering LDR1's!
Cheers!
Morten
Tortuga Audio - Handcrafted audio gear for music lovers

 

[CaptainWatt]

Tortuga Audio Releases LDR1 Passive Preamplifier

Happy Thanksgiving Weekend!

We're pleased to announce the release of the LDR1 Passive Preamplifier that uses digitally controlled analog light dependent resistors for attenuation with exceptional sonic performance. The LDR1 is a single input, dual input preamp. The LDR1 is built around the same technology and design as the LDR6 which has 6 inputs and a single output.

More info can be found at Tortuga Audio | Handcrafted audio gear for music loversTortuga Audio

Cheers!

Morten

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

 

[ackcheng]

Thanks! Will there be a balanced version?

 

[CaptainWatt]

Thanks! Will there be a balanced version?

We are considering it but a final decision to develop/offer would depend on the market demand for a balanced unit. While we haven't done any design/optimization on this configuration I suspect the current form factor would accommodate 3 balanced inputs and 1 balanced output using XLR connectors but not six like the LDR6. Perhaps an LDR3B?

A balanced configuration would double the number of LDRs from 4 to 8 for each input along with the doubling of the core control hardware. The same microprocessor could be used since it has sufficient spare input/outputs. Of course a revised board would need to be designed but there's sufficient real estate for this. The software modifications should be relatively minor.

Minor variations in LDR performance can be corrected for within the software as is currently done with the unbalanced LDR1/LDR6. Doubling up the number of LDRs that need to be closely matched gets a bit messy but I believe it's entirely doable by extending the same testing and matching methodology and tools we currently use for the unbalanced version. I frankly wouldn't even think of executing a balanced LDR design if we didn't employ a software based digital controller.

Most likely a balance unit would be priced higher due to the additional hardware and time to assemble, test and fine tune a more complex design but I wouldn't venture a guess by how much until we got further into the design mods/planning.

I'm curious to know your views on using balanced signals. Do you favor it generally regardless of signal path length or do you have long runs between source & amp which are more susceptible to noise/hum?

Would availability of an balanced unit be a key factor in a buy decision?

I would welcome any additional comments or insights you or other readers have on the subject of a balanced LDR passive preamp?

Cheers!

Morten

 

[CaptainWatt]

Check out the recent user review of our new LDR1. High praise indeed!

"Let me state up front that the LDR1 is the most pure, neutral, transparent, noise-free and grain-free component I have ever heard." - Forum | Tortuga AudioTortuga Audio

Cheers!

Morten

 

[CaptainWatt]

Nice review of our LDR6 Passive Preamp on HiFiPig.com.

There is just a sense of absolutely everything having been stripped free of fuzz and imprecision. Instrumental placement isn’t approximate or inferred. Instead, instruments are precisely located at a fixed and exact distance from the others with the space between performers and the characteristics of the recording environment jaw-droppingly obvious.

… the LDR6 produces a sound completely free of colouration, with a soundstage that was just consistently deeper and better resolved than with any other passive pre-amp I have ever used.

…suitably matched, sonically, the LDR6 is an absolute gem. Jaw-droppingly transparent, with faultless microprocessor control, this pre-amp provides a level of transparency usually the domain of hair shirt enthusiasts, with the convenience of remote control.

It’s possibly the most transparent pre-amp I’ve yet used.

Full review can be found at: Tortuga Audio LDR6 Passive Pre-amp | Hifi Pig

Cheers!
Morten

 

[CaptainWatt]

We're making progress on the balanced version of our LDR Passive Preamplifier. Here's a couple of pics.
More info can be found here.

Cheers!
Morten

An externally hosted image should be here but it was not working when we last tested it.

 

[Speedskater]

Remember to connect each XLR pin #1, directly to the chassis and not to the audio circuit ground.

 

[CaptainWatt]

Remember to connect each XLR pin #1, directly to the chassis and not to the audio circuit ground.

Hi Kevin,

Thanks for your comment.

I agree that grounding pin #1 is considered best practice these days with balanced connectors between primary components with active circuitry. Perhaps the best overview of this can be found in Rane's technical note on Sound System Interconnection which can be found at: http://www.rane.com/pdf/ranenotes/Sound_System_Interconnection.pdf

Rane's recommended approach (the best approach!) is summarized in the following pic.

That said, when it comes to placing a passive attenuator (unbalanced or balanced) between a source and power amp, I submit that the cleanest (least noise) approach is to not ground the common if it isn't needed.

In its simplest form, a balanced attenuator is a variation on the conventional L-Pad attenuator typified by a potentiometer per the diagram below.

In our passive preamps, the audio signal pathways are optically isolated from the DC power supply via the LDRs - signal and power commons are not joined. Nor is the chassis itself grounded since neither the power nor the signal touch the box - they just pass through via the printed circuit board and some wire (which are also electrically isolated from the chassis). As far as the audio signal is concerned, the preamp is just a wire with a built in variable voltage divider.

Hence, at least as things stand right now, the plan is to not tie pin #1 to the chassis. We shall see if this approach survives the prototype testing but I'm reasonably sure it will.

Of course feel free to comment.

Cheers,
Morten

 

[Overkill Audio]

Good reference

Hi Morten,

Just a quick note say that I admire your "purist" design philosophy.
Your volume control will make a great reference point to ensure that digital volume is being implemented in a totally non decimating manor.

Personally I use a dedicated PC or lap top as my high quality music source and run everything else through an AV amp.

What price is your volume control?

Thanks
Derek.

 

[CaptainWatt]

Hi Morten,

Just a quick note say that I admire your "purist" design philosophy.
Your volume control will make a great reference point to ensure that digital volume is being implemented in a totally non decimating manor.

Personally I use a dedicated PC or lap top as my high quality music source and run everything else through an AV amp.

What price is your volume control?

Thanks
Derek.

Hi Derek,

Thanks. But just to avoid any misunderstanding by people reading this, the LDR Passive Preamp is a digitally controlled "analog" volume control.

Aside from vinyl, all of my music is now ripped and resident on a PC in my office/shop with backup to a network server plus a synced copy to a cheap laptop in my living room where my big rig is located. I'm a big fan of using GoodSync for backup/syncing.

In fact I've dumped all my CD cases years ago and have parked all the CDs/inserts in big flippers that are collecting dust on a shelf. I've literally not looked at my archived CD's in over a year. Hi-rez digital is the future in my view - vinyl notwithstanding.

The single input/dual output LDR1 is $1195 and the six input/single output LDR6 is $1475. Note that these are both unbalanced RCA I/O. More info at: Products/Pricing |

Pricing on the Balanced LDR3B Preamp hasn't been settled yet. I'm targeting around $1800 and want to keep it under $2k worst case. Won't know until more of the development work is completed.

Best,

Morten

 

[Overkill Audio]

Thanks Morten, sounds like a good value product, I can see that you spend a lot of time and effort on R&D as well as assembly.
Cheers
D.

 

[CaptainWatt]

Potential DIY LDR board including IR remote function

As we continue to evolve the LDRx Preamp product line, it's been suggested that the DIY community may be interested in a DIY LDR volume control board.

Without going too far into the spec weeds, the LDR board could have the following characteristics:

1) Digitally controlled single ended volume control using matched LDRs
2) Microcontroller with embedded proprietary software including customized matching curves for the LDRs installed on the board
3) Accommodates 2-3 different selectable inputs
4) Input switching would be via LDRs working as switches in lieu of relays
5) Includes IR receiver with the following control functionally via external remote:
a) power on/off toggle
b) raise/lower volume
c) left/right channel adjust
d) channel balance adjust reset
e) input select
f) mute
6) Most, if not all, of the IR remote functionality listed above would be duplicated via digital or analog inputs. For example, volume could be controllable via either a 0-5 VDC input (from an external pot) or via an external encoder A/B leg inputs. On/Off could be via an external push button switch etc.
7) No on board power supply - would require external 5 VDC supply

I'd be very interested in hearing from forum members on their interest level and welcome any comments or suggestions.

Cheers,
Morten

 

[kuribo]

I would be very interested as long as it had balanced inputs/outputs.

 

[talkinghead]

I would also be very interested in a DIY balanced input/output LDR volume control board.

 

[CaptainWatt]

I've started another thread on the topic of a DIY LDR preamp control board.

Here's the link to the thread: http://www.diyaudio.com/forums/vend...dio-ldr3x-diy-preamp-controller-w-remote.html

 

[CaptainWatt]

New Design/Look For Balanced Passive Preamp

Here's a preview of the new look of our upcoming LDR3B Balanced Passive Preamp (and other products). Anodized brushed aluminum with carbonized bamboo sides. More info here: Update On Balanced LDR3B Passive Preamp (rev 3.2) | Tortuga Audio