Customer Projects & Pics with the LDR3x Preamp Controller

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tortugaranger

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Re: Customer Projects & Pics with the LDR3x Preamp Controller
« Reply #40 on: 30 Dec 2013, 02:30 pm »
I am in the process of building Aikido tube preamplifier with Tortuga LDR3x volume control. Here's the pic of the work in progress. Notice the Tortuga board "sandwiched" on top of Aikido board.

There's a level of poetic symmetry to your project. The Aikido tube preamp was the very preamp project I was building 5 years ago that led me to "discover" LDR volume control and eventually start Tortuga Audio.

I was frankly a bit disappointed in the Aikido when I first got it running. I was using an Alps Blue Velvet pot for volume control at the time. I replaced the Alps with a very rudimentary LDR volume control circuit and was astounded at the difference! I soon lost interest in the Aikido (and active preamps more generally) and continued working on various configurations of LDR attenuators. After another 2 years of quiet development, Tortuga Audio was founded and so the story continues.

I look forward to reading about how your Aikido tube preamp project sounds relative to the pure passive version.  I believe there's a compelling case to be made for why every active preamp (solid state or tube) would benefit greatly from a Tortuga Audio LDR preamp/volume controller.

Cheers,
Morten


33na3rd

Re: Customer Projects & Pics with the LDR3x Preamp Controller
« Reply #41 on: 30 Dec 2013, 05:02 pm »
I am in the process of building Aikido tube preamplifier with Tortuga LDR3x volume control. Here's the pic of the work in progress. Notice the Tortuga board "sandwiched" on top of Aikido board.





Sweet!
What tube set are you planning to use?

ClefChef

Re: Customer Projects & Pics with the LDR3x Preamp Controller
« Reply #42 on: 30 Dec 2013, 05:47 pm »
6n1p - 6n6p.

ClefChef

Re: Customer Projects & Pics with the LDR3x Preamp Controller
« Reply #43 on: 7 Jan 2014, 10:05 pm »
Here's the latest Aikido build with Tortuga LDR3x controller. Relay board had to be mounted upside down to move signal paths further from power supply. The board also houses 12v regulator. The power supply is split - Aikido is powered by chassis mounted Hammond power transformer, Tortuga is powered via "Wall-wart" power supply.

Tortuga remote controls inputs, power on/off, volume, balance. All in all very successful build, although it was the most complex and labor intensive one so far.











33na3rd

Re: Customer Projects & Pics with the LDR3x Preamp Controller
« Reply #44 on: 7 Jan 2014, 11:39 pm »
Very, very, nice ClefChef!

You'll have to let us know how it sounds compared to your previous builds. Your Amps & Speakers look lovely too!

Jeff

ClefChef

Re: Customer Projects & Pics with the LDR3x Preamp Controller
« Reply #45 on: 7 Jan 2014, 11:53 pm »
It is difficult to say how exactly it sounds or how different since I am still experimenting with tube bias points. It definitely sounds different. It could be partly due to Tortuga controller and its lower impedance (10k vs 50k pot), or tube rectifier, ordifferent coupling capacitors - will be searching and auditioning for good combination.

I built many Aikido's and kept best one for myself, so you may say I have a reference.

At the moment aikido output stage is biased "hot" which makes it sound heavier and slower than I would prefer. Going to raise plate V and drop cathode current - this tends to make things sound livelier. I am splitting hairs though - currently the preamp would easily outperform majority tube preamps I had opportunity to listen to.

To remain on main topic I have to note that Tortuga is a huge improvement over the usual motorized alps blue pot or relay controlled stepped attenuator.

tl1000sv

Roll Your Own LDR3x Display
« Reply #46 on: 14 Jan 2014, 08:21 am »
After following the LDR product development for a few months, when Tortuga Audio announced the upcoming Hi-Z capability of the LDR3x in October, I resolved to build one.  Like some other customers, I felt that feedback on volume level and changes were capabilities that I would prefer.  Notably, Morten swiftly resolved the latter with the “LED fast blink” feature.

While researching the project, I realized that a compatible volume display could be developed without modifying the LDR3x itself.  The LDR3x’s digital control of the attenuation circuit, plus the availability of comprehensive documentation make this possible.  So in the spirit of DIY, I decided to “roll my own” display using a separate microcontroller.  While it was for my own benefit and purposes, I think it exemplifies the value of Tortuga Audio’s extremely open design philosophy for the LDR3x, demonstrating its capability to be seamlessly integrated into other audio products.

Perhaps an obvious question: would I choose to do it again now that the DM1 is available?  Hard to say, but I am certainly happy with the results.  With the second micro, I was able to implement benefits to operational feedback that are both logical and assuring.  Examples include visual confirmation of button presses, and fading/scrolling for mode transitions.

What follows is a video demonstration, and a brief technical discussion of the implementation for those who are interested.  Initially, I wired up an 8x8 LED as the display output, but later realized that the same code could easily drive a high resolution (128x64) OLED.  The video shows both displays being run through test procedures.

Video link: http://youtu.be/hpvTTf8rDEI




Like the DM1, the display microcontroller connects using the J4 header, exposing the LDR3x SPI bus and providing access to the IR and encoder pins.  With my implementation, the Alps encoder and infrared receiver are captured and interpreted by the display microcontroller, which then relays commands to the LDR3x by emulating the decoded infrared commands on the J4 IR pin.  For example, if balance mode is selected via the encoder button, the LDR3x receives an IR as if the balance button was pressed on the remote.  The exception is for volume change, which can be transmitted far faster than IR by emulating a quadrature encoder signal on the J4 EA and EB pins.

System state itself is determined through a rule-based model emulating LDR3x behavior and correlating the inputs from the status LED, encoder and IR.  LDR3x SPI (internal communications implementing attenuation and balance) activity is monitored to ensure that a command is not accepted by the display microcontroller at a time that the LDR3x cannot process it.

The system configuration is adjustable via the user interface.  In the video you may note that the display output can be inverted – the 8x8 LED I originally intended to use had its connector on the wrong side so I just turned the display over. Volume can be depicted either in the standard 0-70 steps, or attenuation dB according to the published scale.  I am only planning on wiring up 2 sources, so I added an option to make the source count configurable, such that the LDR3x won’t attempt to switch to a source that doesn’t exist.   All the options are stored in EEPROM, and survive a power-cycle.

Overall, designing the volume display was a very educational and fun project pleasantly divergent from amp construction. I learned how to do a lot of interesting things with microcontrollers!  One of my recent e-mails to Morten said, “Thank you for creating such a cool product that made me do a cool project.”  Such is the nature and essence of the DIY community.  I must say that seeing innovative audio technology implemented in such an accessible manner is very unique.

I have a little more work to do on the final PCB and the display mounting on the front panel, and will post some follow-up pics when that is complete.  I’m especially looking forward to everything being done so I can listen “non-developmentally” in the near future! 

Tim

P.S. Have I mentioned that a volume level display makes the LDR3x much nicer to use?  Go and place an order for a DM1!

TrungT

Re: Customer Projects & Pics with the LDR3x Preamp Controller
« Reply #47 on: 14 Jan 2014, 08:41 am »
Tim

Nicely done, thank you for sharing and making the video.  :thumb:


tortugaranger

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Re: Customer Projects & Pics with the LDR3x Preamp Controller
« Reply #48 on: 14 Jan 2014, 02:48 pm »
Very impressive Tim. All the more so since you pulled this off without any special technical info from me. The custom graphics on the OLED display are a very nice touch.

Based on some of the comments I received from Tim while he was developing his display project it was clear he did a deep dive into the inner workings of the LDR3x and would now and then point out something that didn't make sense or could be improved. I dare say at one point he probably knew better how the controls worked that I did!

Nice job! Congrats.  :thumb:

jtwrace

Re: Customer Projects & Pics with the LDR3x Preamp Controller
« Reply #49 on: 14 Jan 2014, 03:16 pm »
Tim,


That's very impressive!  Do you have an electronics background? 

tl1000sv

Re: Customer Projects & Pics with the LDR3x Preamp Controller
« Reply #50 on: 15 Jan 2014, 05:02 pm »
Thanks Morten, that's high praise.

jtwrace, I know my way around a soldering iron but that's pretty much it for electronics design.  DIY projects are a good way to learn quickly though.

This was my first microcontroller project, which says a lot about the flexibility and robustness of today's devices.

glynnw

My latest Tortuga build
« Reply #51 on: 8 Mar 2014, 06:00 pm »
Wood matches my amps.  Will probably replace sea turtle with smaller knob at some point.




33na3rd

Re: Customer Projects & Pics with the LDR3x Preamp Controller
« Reply #52 on: 8 Mar 2014, 06:07 pm »
Very nice!

tortugaranger

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Re: My latest Tortuga build
« Reply #53 on: 8 Mar 2014, 06:34 pm »
Wood matches my amps.  Will probably replace sea turtle with smaller knob at some point.

Well done Glynn! The Tortuga knob is a special touch. Love that.  :thumb:

Cheers,
Morten

timoteus

Re: Customer Projects & Pics with the LDR3x Preamp Controller
« Reply #54 on: 16 Jun 2014, 11:36 pm »
Cobalt Corian chassis with dual displays.  Still need to put on the feet and the Ibanez collet knob may end up being temporary.





« Last Edit: 26 Jun 2014, 03:52 am by timoteus »

ClefChef

Re: Customer Projects & Pics with the LDR3x Preamp Controller
« Reply #55 on: 17 Jun 2014, 12:06 am »
beautiful work. I would move the boards as close to RCA plugs as possible to reduce the length of signal path.

tortugaranger

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Re: Customer Projects & Pics with the LDR3x Preamp Controller
« Reply #56 on: 17 Jun 2014, 01:31 am »
Cobalt Corian chassis with dual displays.  Still need to put on the feet and the Ibanez collet knob may end up being temporary.

Very cool look and nice clean layout. Congrats.  :thumb:

If you haven't done so yet, I recommend uploading the latest software build which is 1.0.6.   There were numerous bugs in the first few units shipped out that have been resolved. Info on software download/updating can be found here:  http://www.tortugaaudio.com/downloads/

Cheers,
Morten

timoteus

Re: Customer Projects & Pics with the LDR3x Preamp Controller
« Reply #57 on: 17 Jun 2014, 02:06 am »
One more with displays on and feet on.  Many thanks Morten!



Pictures keep disappearing, just check in Gallery at left.
« Last Edit: 10 Nov 2014, 03:54 am by timoteus »

craig sawyers

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Re: Customer Projects & Pics with the LDR3x Preamp Controller
« Reply #58 on: 13 Feb 2016, 12:28 pm »
My take on the LDRXB.  Front and rear panels made to my drawings, including screen printing of rear panel by https://www.modushop.biz/site/ .  Grey insert routed out by me.  Knob, courtesy of eBay from China.  All internals by Morten.  Input wiring from http://www.wires.co.uk/acatalog/silk_covered_silver.html .  The primary input is a Logitech Transporter streamer located right next to the pre.

Sound quality?  Stunning.  Walks all over my Audio Research LS3 active pre.  Brought tears to my wife's eyes - for good reasons!






tortugaranger

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Re: Customer Projects & Pics with the LDR3x Preamp Controller
« Reply #59 on: 15 Feb 2016, 06:45 pm »
My take on the LDRXB.  Front and rear panels made to my drawings, including screen printing of rear panel by https://www.modushop.biz/site/ .  Grey insert routed out by me.  Knob, courtesy of eBay from China.  All internals by Morten.  Input wiring from http://www.wires.co.uk/acatalog/silk_covered_silver.html .  The primary input is a Logitech Transporter streamer located right next to the pre.

Sound quality?  Stunning.  Walks all over my Audio Research LS3 active pre.  Brought tears to my wife's eyes - for good reasons!

Very nice unit Craig. Well done! Enjoy.