AudioCircle

Industry Circles => Tortuga Audio => Topic started by: tortugaranger on 13 Sep 2013, 07:57 pm

Title: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: tortugaranger on 13 Sep 2013, 07:57 pm
Check out this VERY nice DIY passive preamp project that one of our LDR3x customers put together and posted over at DIYAudio. Excellent workmanship.  :thumb:

http://www.diyaudio.com/forums/vendors-bazaar/230114-tortuga-audio-ldr3x-diy-preamp-controller-w-remote.html#post3631154 (http://www.diyaudio.com/forums/vendors-bazaar/230114-tortuga-audio-ldr3x-diy-preamp-controller-w-remote.html#post3631154)
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: poseidonsvoice on 13 Sep 2013, 11:02 pm
I quite agree. Very nicely done. DIY rocks!  :thumb:

Best,
Anand.
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: glynnw on 18 Sep 2013, 07:19 pm
My simple implementation.  Infrared receiver in upper left corner in inside view.  Signal wire is very short solid siver and have solid copper RCAs on order for rear.

(http://www.audiocircle.com/image.php?id=87117)

(http://www.audiocircle.com/image.php?id=87115)

(http://www.audiocircle.com/image.php?id=87116)
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: TrungT on 22 Sep 2013, 10:29 pm
(http://www.audiocircle.com/image.php?id=87371)


 (http://www.audiocircle.com/image.php?id=87372)


 (http://www.audiocircle.com/image.php?id=87373)
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: TrungT on 22 Sep 2013, 10:31 pm
(http://www.audiocircle.com/image.php?id=87374)


(http://www.audiocircle.com/image.php?id=87375)


 
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: TrungT on 22 Sep 2013, 10:34 pm
(http://www.audiocircle.com/image.php?id=87380)


 (http://www.audiocircle.com/image.php?id=87381)


 (http://www.audiocircle.com/image.php?id=87382) 
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: WireNut on 22 Sep 2013, 11:17 pm
TrungT,

Very cool. I like the orange paint  :thumb: The LED shining thru the smoke front was a great idea. Very cool looking to me  8)
Is that a Par-Metal or Hammond case?




Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: tortugaranger on 22 Sep 2013, 11:29 pm
That's what I call Chevy V8 engine block orange. Go bold or go home! Nice work. How's it sound?
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: TrungT on 23 Sep 2013, 02:26 am

Thank you.  :D 
The remote control work smoothly, sound great at low to high volume.
Sound awesome with Auralex Vega, and will test with MyteK DAC next week.

Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: TrungT on 22 Oct 2013, 11:48 pm
Another build for a friend, unbalanced.
 (http://www.audiocircle.com/image.php?id=88715)


 (http://www.audiocircle.com/image.php?id=88716)


 (http://www.audiocircle.com/image.php?id=88717) 
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: Bob in St. Louis on 23 Oct 2013, 12:57 am
I didn't know TT was a DIYer!?!?!?
Well done, beautiful work Sir!
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: TrungT on 23 Oct 2013, 01:15 am
^^^^^
Thank you.   ;)
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: playntheblues on 23 Oct 2013, 01:24 am
Nice work Trung. I couldn't believe all of your projects on the table and on the shelve.  You rock :rock: :rock: :rock:
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: TrungT on 25 Oct 2013, 02:45 am
Thank you.
So much to do and so little time.  ;)
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: MikeLdiy on 8 Nov 2013, 03:38 am
Wow, everyone has a great looking build!  I need mechanical skills but thought I'd post some pics anyways.  Made a mistake on one of the PCBs and still need to clean up the wiring but it works!  Sounds good too.  Used LDRs as input switches instead of relays.
(http://www.audiocircle.com/image.php?id=89617)

(http://www.audiocircle.com/image.php?id=89618)

(http://www.audiocircle.com/image.php?id=89619)

Cheers,
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: tortugaranger on 8 Nov 2013, 04:19 pm
Here's a pic a recent LDR3x customer send me. Nice compact layout and wiring.

Cheers,
Morten

(http://www.audiocircle.com/image.php?id=89633)
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: tortugaranger on 8 Nov 2013, 04:22 pm
Used LDRs as input switches instead of relays.

Thanks for posting this Mike.
How did you pull off the LDR based input switching in terms of the circuit board etc? This may be something others would be very interested in.

Cheers,
Morten
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: MikeLdiy on 8 Nov 2013, 07:35 pm
Hi Morten,

First off, thanks for the product for the DIY community.  This makes tweaking and playing a reasonably affordable hobby!  Also, great implementation using the LDRs!!  They are a beast to work with.  Can't imagine the time spent matching these things!

Regarding the LDR switching, I have the single ended version of the LDR3x:
1.  I took the +5.0V from your on-board regulator coming out of the power terminal +5.0V and used this as power for the LDR diode.  I 've powered the unit via a +12V linear regulator.
2.  Series POT multiturn resistor from +5.0V to LDR diode (anode).  Value was 500R set to 250R.  Used one each for left and right channels.  This of course is times 3 because of the 3 input selection coming from your board so 6 in total.
3.  GND is not connected to the "bottom"/"negative/cathode of the LDR diode.  This is left floating.
4.  Connected the cathode of the LDR from each *channel* to the "In1","In2", "In3" of your board.
5.  Paralleled all the Left channel source inputs after the LDR resistors (other side of course connected to source).
6.  Paralleled all Right channels sources, same as above.  This gives the switched L and R signals that go into RI and LI of your board.
7.  GND of all sources are connected together and plumbed to AG to your board.
8.  Took the DMM and monitored the resistor value of the LDR with no loads or sources connected.  Tweaked the POT till each LDR resistance was 50 ohms.  As close as I could get it.  Use the SR3 version of LDR from Newark.  Pulling around 16mA through the LDR diode.
9.  Did not test for repeatability, temperature or anything else.

One thing to note is the LDR resistance does't change on a dime so there is some area while switching that the LDR is between sources and possibly lowish resistance.  Seems to work fine at home right now though.  I've tried 2 sources full ON and did some switching.  Everything survived but I can not guarantee this will work for everyone; however, this may not be a big deal, just something I noticed.  I made a custom PCB for myself that has LDR footprint and relay footprints in parallel just in case.  You could easily do this without a PCB though.

Let me know if you need more information, sorry for the fast typing, a bit short on time, thanks again!

Cheers,
Mike
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: MikeLdiy on 10 Nov 2013, 05:11 pm
Couple of last pics.  Got front panel LEDS on.  Got all the boards mounted with more room to spare than I thought :duh:.
LDR3x Tortuga Board :icon_twisted:, Low noise power supplies based on TPS7A4700RGWT and TPS7A3301RGWT for phono stage and LDR3x, phono stage (MM and MC) and Input Switch boards!  Still need to clean up wiring but have to do a long listening session, so far sounding really good!  Convenience is great too!  Looking forward to more Tortuga Products!

(http://www.audiocircle.com/image.php?id=89778)

(http://www.audiocircle.com/image.php?id=89779)
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: ClefChef on 14 Nov 2013, 02:18 am
(http://www.audiocircle.com/image.php?id=89895)


(http://www.audiocircle.com/image.php?id=89896)


(http://www.audiocircle.com/image.php?id=89897)

I would imagine that 15V walwart supply would work just as well, with some internal regulation for input relays, and that is what I will do on my next project. I also installed a ground lift switch which I found to be a necessity in some situations.


(http://www.audiocircle.com/image.php?id=89898)

Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: MikeLdiy on 14 Nov 2013, 10:39 pm
ClefChef, that is a very nice case!  How did you do the front panel if you don't mind me asking?
Cheers,
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: ClefChef on 14 Nov 2013, 11:03 pm
ClefChef, that is a very nice case!  How did you do the front panel if you don't mind me asking?
Cheers,

Thanks!
Front panel was done using drills, countersinks, glue, and dry transfer lettering.
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: MikeLdiy on 14 Nov 2013, 11:44 pm
Thanks!  I need to re-do my case.  Will investigate the tools.
Cheers,
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: tortugaranger on 14 Nov 2013, 11:47 pm
Outstanding job ClefChef!!  :notworthy:
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: WireNut on 14 Nov 2013, 11:58 pm

ClefChef, that is a very nice case!  How did you do the front panel if you don't mind me asking?
Cheers,



Yeah, show us how you built it :thumb:

DIY build thread  :bounce:



 
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: ClefChef on 15 Nov 2013, 12:16 am

Yeah, show us how you built it :thumb:

DIY build thread  :bounce:

Take something like this: http://www.ebay.com/itm/140879277940?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649 (http://www.ebay.com/itm/140879277940?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649)

Take the front panel, carefully mark holes, tap those marks with the punch, drill fine pilot holes, for diode indicators drill larger diameter from inside for snug diode fit, use good deburring tool. To mound IR sensor drill pilot hole, then larger hole, then from the inside drill out the "groove" CNC style drilling two holes and using progressively larger diameter drill bits.
Glue LED's and IR using your favorite superglue. Use permanent black marker to touch up bare aluminum. Do lettering using your favorite dry transfer lettering sheets.

Similar process for back panel RCA - stepped drill tool.

WEAR SAFETY GOGGLES AT ALL TIMES!!!

That's it...:)

Here's the inside of another one. This time I had to build relay input board myself, note slightly different input-output grounding schematic:

(http://www.audiocircle.com/image.php?id=89920)

Signal wiring is silver, the rest - mil spec Teflon wire. Power supply - LM317T regulated 12V (for relay board) fed by Hammond PT. RCA's - CNC copper.

I build all my gear for my own personal use, sometimes I pass it on when new "challenges" arise.
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: AluminatiSound on 15 Nov 2013, 01:06 am
I'm half way tempted to buy one of these boards just to make a cool looking case.

But I want to re case a PlayStation 4 as well!
 
So many things to do, not enough time  :lol:

Best,
Matt
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: tl1000sv on 15 Nov 2013, 09:34 pm
Clef, nice build on the second one too.  I notice you didn't put in a 5v supply on this one.  Is that simply because you selected 12v relays for the second build?  Also, on the first one, why didn't you use the 5v output on the LDR board?  I'm not using it either, although I am curious of your reasoning.

I'm actually mid-build on a very similar case construction, although I am adding a square LED matrix to the front panel to display the attenuation "step" and input source instead of discrete LED's.  Will post pics when it's together.

No doubt some will wonder how that is possible with no access to the step register in the LDR3x microcontroller, but I have devised two separate strategies that I think will work.  Just waiting for my LDR3x to arrive so I can test them out :-)

Tim
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: ClefChef on 15 Nov 2013, 09:53 pm
Clef, nice build on the second one too.  I notice you didn't put in a 5v supply on this one.  Is that simply because you selected 12v relays for the second build?  Also, on the first one, why didn't you use the 5v output on the LDR board?  I'm not using it either, although I am curious of your reasoning.

You are correct - in the first one I used 5V relays and 12V relays in the next one. The 5V output on LDR board is for electronic circuits and relay coil current draw would provide minute interferences. It is always best to keep supply rails separate or at least regulated separately. 7812 to relays +7805 for LDR = double regulated voltage for LDR - good practice.
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: tortugaranger on 19 Nov 2013, 07:38 pm
No doubt some will wonder how that is possible with no access to the step register in the LDR3x microcontroller, but I have devised two separate strategies that I think will work.  Just waiting for my LDR3x to arrive so I can test them out :-)

One way I know could work is any SPI compatible device that can accept an 8 bit data string. That's how the microcontroller talks to the digital resistors that control voltage to the LDRs so the info is there.
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: WireNut on 19 Nov 2013, 07:51 pm

Take something like this: http://www.ebay.com/itm/140879277940?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649 (http://www.ebay.com/itm/140879277940?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649)


That's a heck of a deal on that case. Turned out really good  :thumb:

 
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: tl1000sv on 19 Nov 2013, 08:55 pm
Awesome.  Was going to inspect the IC's in front of the LDR's to see if I could figure that out, but you have confirmed a third approach which is probably the simplest.  I actually expected a variable voltage out from the microcontroller for each channel.  Thanks!

One way I know could work is any SPI compatible device that can accept an 8 bit data string. That's how the microcontroller talks to the digital resistors that control voltage to the LDRs so the info is there.
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: 33na3rd on 23 Nov 2013, 08:18 pm
Thanks to Morten, my Melos SHA Gold is playing music again after being broken for two years! When it broke, there were no parts available to repair it.


(http://www.audiocircle.com/image.php?id=90340)
Out with the old, and in with the new! These two boards perform the same functions, notice how much smaller the LDR3X board is!


(http://www.audiocircle.com/image.php?id=90342)


(http://www.audiocircle.com/image.php?id=90341)
The IR Receiver is mounted in the lower lefthand corner of the Meter, same place as the original. I did enlarge the opening for the IR Receiver, but it probably wasn't necessary. I attached the IR Receiver with 3M automotive double sided acrylic tape. The yellow LED on the right side is for the Status, it replaced the original mute indicator. I chose yellow to keep with the old school look of the preamp.


(http://www.audiocircle.com/image.php?id=90343)
Playing music again!

I'm really happy to have my Melos back again. While I'm not able to use the entire range of the LDR3X because of the preamps gain, the range between steps is very small & smooth. No problem finding just the right volume level. The LDR3X is major asset to active preamps, as well as being the top choice for passives.

In the near future, I would like to build a LDR3X with either a Pass B-1 Clone or Aunt Corey's Buffer.

I would like to close by saying how impressed I am by everyones' original projects! I feel like I cheated because I merely fixed my broken preamp!

Jeff

 
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: TrungT on 23 Nov 2013, 09:15 pm
Jeff
That's a great work and fixed the Melos.  :thumb:
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: WireNut on 23 Nov 2013, 09:20 pm

Thanks to Morten, my Melos SHA Gold is playing music again


No kidding, that's great news. Wish I still had my Melos Sha-1...


Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: 33na3rd on 24 Nov 2013, 12:32 am
Thank you TrungT!

WireNut, I keep thinking that a SHA-1 with a LDR3X would be a SHA Gold! I still see nice SHA-1's on Audiogon from time to time. Of course now that my Melos is going again, I hope to be spending less time on that site!
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: tortugaranger on 24 Nov 2013, 12:57 am
Thank you TrungT!

WireNut, I keep thinking that a SHA-1 with a LDR3X would be a SHA Gold! I still see nice SHA-1's on Audiogon from time to time. Of course now that my Melos is going again, I hope to be spending less time on that site!

Interesting project Jeff. Can you tell if it sounds like you remembered it or if it's any different?
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: 33na3rd on 24 Nov 2013, 01:50 am
Interesting project Jeff. Can you tell if it sounds like you remembered it or if it's any different?

Hello Morten!

Does it sound different? Well, it's been two years since i've heard it, and the expensive NOS tubes that were in it have mysteriously gone MIA. I stuck a spare pair of regular Electro Harmonix 6922's that are not matched in it, and all I can say is that it sounds marvelous!

I've never had issue with the sound of that preamp. Before I got the SHA Gold, most preamps lasted around here a year or two, at most. I ran the SHA Gold daily for 16 years before the Pho-Tentiometer broke, and never thought about getting a different preamp. There are some pieces of gear that I regretted getting rid of over the years, but there was never a preamp on that list. (Well, OK, the Apt Holman did have a pretty sweet phono section!) The magic of the Melos SHA Gold was the delicate Pho-Tentiometer, and your devices are the modern heir to that legacy, except that you've figured out how to make them rugged and affordable! When I fired the Melos back up, it was like reuniting with an old friend.

Yes, it does sound like I remember, it sounds wonderful. The tonal balance does not change with volume changes, it simply gets louder or softer. I did notice that you can turn the LDR3X all the way down. Even at minimum, the Melos Pho-Tentiometer would send some signal through. The Melos has an old school warmth to it, but yes, I can tell that the LDR3X is not adding or taking anything away from the gain stage behind it.

I can also tell that when the warranty on my Preamp that recently came back home expires, I would love to have one of your LDR units inside!
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: ClefChef on 30 Dec 2013, 06:00 am
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.


(http://www.audiocircle.com/image.php?id=92173)
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: TrungT on 30 Dec 2013, 06:10 am
^^^^^
Nice.  :thumb:
Please let us know how's sound.
Thanks for posting.

Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: tortugaranger 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

Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: 33na3rd 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?
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: ClefChef on 30 Dec 2013, 05:47 pm
6n1p - 6n6p.
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: ClefChef 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.


(http://www.audiocircle.com/image.php?id=92640)

(http://www.audiocircle.com/image.php?id=92641)

(http://www.audiocircle.com/image.php?id=92643)


(http://www.audiocircle.com/image.php?id=92644)
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: 33na3rd 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
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: ClefChef 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.
Title: Roll Your Own LDR3x Display
Post by: tl1000sv 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 (http://youtu.be/hpvTTf8rDEI)

(http://www.audiocircle.com/image.php?id=92984)
(http://www.audiocircle.com/image.php?id=92983)

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!
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: TrungT on 14 Jan 2014, 08:41 am
Tim

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

Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: tortugaranger 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:
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: jtwrace on 14 Jan 2014, 03:16 pm
Tim,


That's very impressive!  Do you have an electronics background? 
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: tl1000sv 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.
Title: My latest Tortuga build
Post by: glynnw on 8 Mar 2014, 06:00 pm
Wood matches my amps.  Will probably replace sea turtle with smaller knob at some point.
(http://www.audiocircle.com/image.php?id=96049)

(http://www.audiocircle.com/image.php?id=96050)
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: 33na3rd on 8 Mar 2014, 06:07 pm
Very nice!
Title: Re: My latest Tortuga build
Post by: tortugaranger 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
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: timoteus 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.

(http://www.audiocircle.com/image.php?id=101486)


(http://www.audiocircle.com/image.php?id=101084)
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: ClefChef 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.
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: tortugaranger 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/ (http://www.tortugaaudio.com/downloads/)

Cheers,
Morten
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: timoteus on 17 Jun 2014, 02:06 am
One more with displays on and feet on.  Many thanks Morten!

(http://www.audiocircle.com/image.php?id=101485)

Pictures keep disappearing, just check in Gallery at left.
Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: craig sawyers 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!

(http://www.audiocircle.com/image.php?id=137074)

(http://www.audiocircle.com/image.php?id=137075)

Title: Re: Customer Projects & Pics with the LDR3x Preamp Controller
Post by: tortugaranger 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/ (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 (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.