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Tortuga Audio LDR3x DIY Preamp Controller w/ Remote

What type remote do you prefer to control your preamp?

  • Use a dedicated custom remote?

    Votes: 2 10.5%
  • Use the Apple Remote?

    Votes: 5 26.3%
  • Use an app on my iPhone, iPad or Android?

    Votes: 9 47.4%
  • Custom plus apps?

    Votes: 2 10.5%
  • Apple plus apps?

    Votes: 1 5.3%

  • Total voters
    19
  • Poll closed .
Tortuga LDR Volume/Preamp Controller with OLED Display & Remote

As I mentioned earlier in another thread, we are planning on coming out with an LDR based preamp controller board (the LDR3x) for the DIY community hopefully before the end of April. This is a result of development work we're doing on our line of LDR based passive preamps.

The intent is to offer a LDR based board around which you can build either a passive or active preamp that provides exceptional LDR attenuation, selection from 3 input signals, and be controllable via IR remote as well as at the unit.

Also, by using a pair of these in a master/slave configuration, you'll also be able to configure a balanced LDR based preamp. We still have some testing to do on the balanced configuration but I'm highly confident it will work nicely.

More info can be found per a recent post on our website: Tortuga Audio Plans LDR3X Preamplifier Controller for DIY Community | Tortuga Audio

The LDR3X preamp controller board will likely be viewed as pricey when compared to typical dirt cheap Chinese made audio boards. This board will be made in relative small quantities here in the US. Also, quite a bit of testing and custom tuning goes into each board given the unique characteristics and variability of LDRs. By its nature, this doesn't lend itself to mass production and low cost. As least not yet. I'm trying to keep it under $300.

I value your inputs and suggestions. In fact, every member on DIYAudio who provides constructive input, comments, suggestions or questions via this thread will be entered into a drawing from which I'll randomly choose 1 winner to receive a free board (including shipping) once they become available. So have at it and thanks. :D

Cheers,
Morten

ldr3x_pcb1_small.jpg
 
Last edited:

Twillyj

Member
2013-04-07 2:35 am
CaptainWatt, are you still on target for the 3 input version? IMHO, this configuration will serve the widest market, as 6 is a bit much for the average resi system, and just 1 isn't enough. Having an option for balanced/unbalanced outputs is a big plus, and the remote is essential. At under $300 this would be the only product on the market that I'm aware of that does this. I have just a few components that feed into a receiver, and then to a driverack which controls my amps. I need a true preamp that will not discolor the signal as my makeshift receiver is today.
 
CaptainWatt, are you still on target for the 3 input version? IMHO, this configuration will serve the widest market, as 6 is a bit much for the average resi system, and just 1 isn't enough. Having an option for balanced/unbalanced outputs is a big plus, and the remote is essential. At under $300 this would be the only product on the market that I'm aware of that does this. I have just a few components that feed into a receiver, and then to a driverack which controls my amps. I need a true preamp that will not discolor the signal as my makeshift receiver is today.

Watt? Oh. Yes! As you can see in the pic, the sausage making is well along. The prototype LDR3x board is located center left. All those red wires are part of a patch cable back to a microcontroller development board. Looks (is!) messy but this arrangement allows rapid updates to the software without having to pull/replace chips.

The foreground shows a graphics display board. I currently don't plan on offering a graphics display option with the LDR3x but we're going to use this same board in our updated lineup of LDR preamp products which will include a display of dB level etc.

At this point, development of the LDR3x is pretty far along. Everything works! Will be making final tweaks on the board design and ordering the final (hopefully!) development board by the end of the week. Once we have that board and it checks out, we can order a production run.

So I'm thinking that by the end of April we should be good to go. The only wrinkle in the timing is I may be moving to another location here in town between now and mid-May and you know how disruptive moves can be.

I do plan on finalizing the part/supplier/cost database this week and once that's done we'll set the price for the board and start taking pre-orders which will likely be at a discounted price until we start shipping. Next week I'll also post access to downloading a near-final draft of the LDR3x Operating Manual. Going to be a busy week!

Best,

Morten

ldr3x_makingsausage_300x400.jpg
 

Twillyj

Member
2013-04-07 2:35 am
Morten,
Thank you for taking the time to detail your progress. There is a significant gap in the market for these components in this price range and I think your company is positioned to fill it well. Another supplier is coming offline for a while unfortunately. Curious, where is your company located?
 
Morten,
Thank you for taking the time to detail your progress. There is a significant gap in the market for these components in this price range and I think your company is positioned to fill it well. Another supplier is coming offline for a while unfortunately. Curious, where is your company located?

Thanks. Hopefully this will turn out to be win-win all around. We're located in southwest Florida near the coast - Cape Coral/Fort Myers area. Where hurricane season is just around the corner. :eek:
 
Technical Manual for the LDR3x DIY Passive/Active Preamp Controller Board

The technical manual is now available for the LDR3x DIY Preamp Controller Board.

The only quid-pro-quo for downloading it is I ask that you subscribe to our Newsletter. Once you've confirmed your subscription you'll receive a Thank You email that will contain a download link. We won't bombard you with newsletter spam. You can always opt out anytime.

Here's a link to subscribe to our newsletter.

The technical manual will give you a fairly decent picture of what the LDR3x can do and how you can interface with it. The current manual is a pre-release version and will no doubt get tweaked a little over the next few weeks but it's in fairly decent shape.

The price for the LDR3x Master Board will be $325. The price for the matched set of LDR3x Master & Slave Boards for balanced inputs will be $590.

We will also be selling an optional custom remote for $45 although you should be able to use your own programmable remote.

We will eventually be selling an optional Encoder and Input Relay Board but those are still being worked on.

We intend to start taking pre-orders for the LDR3x later next week via our website at www.tortugaaudio.com and will announce that as soon as it's available.

Feedback and questions always welcome.

Cheers!
Morten
 

Crom

Member
2012-10-08 10:17 pm
An interesting DIY project for sure! Congratulations on the v positive reviews. Couple of points that might help people to decide if this is for them:

1) Having read this thread and the PDF download from your site I still wasn't entirely sure what I'd be buying - in terms of components (or whether the boards would be pre-populated etc). The thread and PDF mentions 'boards' and the fact that matched LDRs are supplied. It also helpfully says that you'll need to supply a 12v adapter. However, it doesn't seem to indicate whether a full complement of components (with exception of case etc) is included. I don't think that a BOM is called for but just to say that everything's there except..a/b/c...or just replace the word 'boards' with 'kits', if that's what's meant.
2) Other LDR-based kits (ligher note and lightspeed) seem to include a lot of set up, tweakery and impedence matching. How does this design deal with this?

Hope this is helpful. It looks like an interesting project and I'd love to have a crack at the prize draw!

Good luck with the launch and I'll definitely keep an eye on this.
Crom
 
An interesting DIY project for sure! Congratulations on the v positive reviews. Couple of points that might help people to decide if this is for them:

1) Having read this thread and the PDF download from your site I still wasn't entirely sure what I'd be buying - in terms of components (or whether the boards would be pre-populated etc). The thread and PDF mentions 'boards' and the fact that matched LDRs are supplied. It also helpfully says that you'll need to supply a 12v adapter. However, it doesn't seem to indicate whether a full complement of components (with exception of case etc) is included. I don't think that a BOM is called for but just to say that everything's there except..a/b/c...or just replace the word 'boards' with 'kits', if that's what's meant.
2) Other LDR-based kits (ligher note and lightspeed) seem to include a lot of set up, tweakery and impedence matching. How does this design deal with this?

Hope this is helpful. It looks like an interesting project and I'd love to have a crack at the prize draw!

Good luck with the launch and I'll definitely keep an eye on this.
Crom

Hi Crom and thanks for your comments.

The obvious often eludes us and your "what's included" comment is well taken. I'll amend the document to fix that. A graphic will also be helpful - I'll work on that. But I'll also take a crack at clarifying it here.

What it's not.

1) The LDR3x is NOT a kit in the classic sense of here's everything, you put it all together.

2) It doesn't come with a remote.

3) It doesn't come with a power supply.

4) It doesn't come with an enclosure.

What it is.

1) The LDR3x is a fully populated preamp controller board inclusive of custom matched LDRs with one exception. The infrared receiver is provided loose. You can either solder it into the board or locate it remotely from the board (usually near your front panel) and run wires from it to the board.

2) The LDR3x only needs 2 additional items to be a fully functional preamp controller; a 5 or 12 VDC power supply, and a programmable remote.

3) Once you have a power supply and the remote is programmed, you connect your single-ended source (DAC, phonostage etc), your amp, your 5 or 12 VDC power supply, turn it on (via the remote) and you're up and running. Strictly speaking you don't even need an enclosure if you don't mind a functioning spartan mess.

Things we'll likely eventually offer as options but you can source/use your own alternatives.

1) Remote
2) Encoder (you don't need this if you use a remote)
3) 12 VDC wallwart power supply.
4) 3 input relay board

Things we'll likely NEVER offer as options:
1) Enclosures

It's a fluid situation subject to change based on user input/interest but the above is a fair reflection of our current thinking.

Setup/Tweaking Etc.

Each LDR3B is semi-custom built with its own matched set of 4 LDRs including software based correction curves to ensure excellent left/right channel matching. Aside from the hardware items mentioned above, there's no setup/tweaking etc required or even possible.

Like all passive preamps, you need to educate yourself as to whether your particular combo of source and amp are a good match for a passive preamp. I recommend you read our article on the subject which can be found here: Is a Passive Preamplifer Right For You? | Tortuga Audio

Cheers,
Morten
 
what is the total cost, with the discount, for a balanced set up?

We're offering the same 20% pre-release discount on the Master/Slave matched set which is normally priced at $590. So the pre-release discount price is $472.

We still need to set that up on the website/store but it should be up and available by mid-morning US east coast time tomorrow.

Cheers,
Morten
 

Crom

Member
2012-10-08 10:17 pm
Each LDR3B is semi-custom built with its own matched set of 4 LDRs including software based correction curves to ensure excellent left/right channel matching. Aside from the hardware items mentioned above, there's no setup/tweaking etc required or even possible.

Thanks Morten, I've taken a look at the articles on the website - very informative! You mention that buffers may be added to the project but I've heard that they are almost a 'must have', otherwise the output impedance otherwise goes wild, ranging from few hundreds up to 2-3k. An ideal scenario would be to have both input and output buffer - the best you can get - to avoid compromising the transparency. You don't agree with this?

Cheers,
Crom
 
You mention that buffers may be added to the project but I've heard that they are almost a 'must have', otherwise the output impedance otherwise goes wild, ranging from few hundreds up to 2-3k. An ideal scenario would be to have both input and output buffer - the best you can get - to avoid compromising the transparency. You don't agree with this?

Cheers,
Crom

Hi Crom,

If you do a deep dive into the various audio forums including diyAudio you'll find numerous threads discussing the topic of impedance mismatch and variability as it relates to passive preamps in general. I certainly agree that impedance mismatch can be an issue and clearly acknowledge that in our website.

If you place a passive preamp between: a) a source that has a high output impedance, low line stage voltage, weak current capacity; and, b) an amp with low input impedance, you will likely be disappointed in the result, declare passive preamps as being flawed, and advise others to steer clear of passives. Your experience will tell you you're right (in that instance) but you'll still be wrong.

A possible "fix" for the above instance is a buffered passive preamp. However, "buffered passive" is an oxymoron. A buffer, whether solid state or tube, is synonymous with "active". A buffer has a power supply that interacts directly with the audio signal even if it's a unity gain buffer (no amplification). It will indeed solve the impedance mismatch issue between source and amp but will impart its own characteristics onto the audio signal.

I hesitate to suggest a hard and fast rule of thumb but it's likely that if the ratio of amp input impedance to source output impedance is 100:1 or higher that it really doesn't matter that the impedance varies widely over the passive's attenuation range. No point getting bogged down in technical minutiae on that. The proof is in the listening.

I personally use mostly SS amps and love the sonic quality of our LDRx preamps. Many of our customers have tube amps and are very impressed with the sonic performance of our passive preamps which is not surprising since tube amps typically have input impedance of around 1M making impedance mismatch a moot point.

I've run 700 ohm DACs into 15K ohm SS amps with our LDR passive preamp in between with excellent results.

Bottom line is passive preamps are not a good fit for every pairing of source & amp. But when they do fit, our LDR passive preamps beat or match most any active preamp for clarity, transparency and honesty to the source material.

Not that there aren't some fabulous sounding active preamps out there. But when you consider the price/fabulous ratio :eek: of those fabulously expensive actives, our LDR passive is quite the bargain.

Cheers,
Morten
 
Production boards and parts have been ordered!

Good news! Orders were placed earlier this week for production boards and parts for the LDR3x Preamp Controller Board.

Barring any last minute glitches we expect to have finished boards ready to ship starting June 24th if not sooner!

If you're interested in the LDR3x Preamp Controller Board, you can still pre-order one at a 20% discount off the regular price. The pre-release discount ends once we have finished boards ready to ship.

Cheers!
Morten
 
The LDR3x DIY Preamp Controller Board is shipping!

Well, it's taken a bit longer than planned but we're pleased to announce that the LDR3x DIY Preamp Controller Board has been released and pre-release orders are shipping! :D

Final pricing is:
Master Board for unbalanced inputs - $295
Matched Master & Slave Boards for balanced inputs - $495
Tortuga Audio IR Remote - $49

You can find more information and purchase the LDR3x via the website/store at: LDR3x DIY Preamp Controller Board | Tortuga Audio

ldr3x_1.jpg


The LDR3x allows you to build your own high performance LDR based passive (or active if you include a buffer) preamp that can be controlled remotely and also locally via rotary encoder/switch or discrete pushbutton inputs and a simple potentiometer.

Built around precisely matched digitally controlled LDRs, the LDR3x offers the DIY'er the ability to build preamp that will rival the audio performance of even the best high end preamps. :bigeyes:

We'll be posting more pics next week and tweaking the technical manual which has been updated as of today (6.29.13) to reflect the final design/build. We still need to include more detailed artwork describing the board and the interfaces.

You'll notice from the pic that the board isn't fully populated. The board has certain functionality that isn't available to the DIY'er and thus those relavant parts are not included. We also plan on using these boards in our future iterations of our own preamp products.

All questions, comments and inquiries welcome.

Cheers,
Morten
 
And we have a winner!

When I first announced that we would be offering the LDR3x DIY Preamp Controller Board, I mentioned that we'd give away a free LDR3x to one forum member from the pool of members who provided input/suggestions prior to releasing the DLR3x for sale.

I'm pleased to announce that diyAudio member Crom is the winner! :D

We'll be popping an LDR3x into the mail later this week and look forward to hearing about Crom's DIY preamp project as it evolves.

[IMGDEAD]http://tortugaaudio2.wpengine.netdna-cdn.com/images/ldr3x_1.jpg[/IMGDEAD]

The LDR3X is a digitally controlled, analog audio preamp controller in the form of a populated 2.5 inches wide by 4.7 inches long printed circuit board.

The LDR3x allows the do-it-yourself (DIY) audiophile enthusiast to build their own exceptionally transparent and articulate audio preamplifer that rivals the performance of even the best high end preamp costing 10-100 times more than the LDR3x. It can be controlled via an optional IR remote, mutl-function encoder and even via discrete digital inputs.

By itself, LDR3x is an unrivaled passive preamp/controller. Mated with a user provided buffer stage (with or without gain), the LDR3x enables the DIY’er to build a truly top notch active preamp.

The LDR3x utilizes light dependent resistors (“LDR”) in lieu of conventional potentiometers or stepped resistive attenuators for volume control. Simply put, LDRs sound better than any volume pot or stepped attenuator.

Precision control of the LDRs and all other functionality of the LDR3x is done via a software driven on-board microcontroller (microprocessor).

Don't hesitate to post a question here or PM me.

More info can be found via our website/store at LDR3x DIY Preamp Controller Board | Tortuga Audio

Cheers!
Morten:)