LDRPot.V1 Stepped Attenuator

0 Members and 1 Guest are viewing this topic. Read 896 times.

tortugaranger

  • Facilitator
  • Posts: 1423
  • Handcrafted high performance audio gear
    • Tortuga Audio
LDRPot.V1 Stepped Attenuator
« on: 13 Nov 2018, 11:50 pm »
I'm pleased to announce that Tortuga Audio is developing the LDRPot.V1 Stepped Attenuator. The LDRPot is intended as a LDR based drop-in replacement/alternative to stereo potentiometers and stepped attenuators.

The LDRPot is an active development and as such is subject to change as we go through the final stages of finalizing the design.

I've published a summary article on the LDRPot which can be found here: https://www.tortugaaudio.com/ldrpot-stepped-attenuator/

I'll provide more info on this as things evolve.

Comments and suggestions are always welcome.

The pic below shows the LDRPot main board with the smaller LDRPot LDR module shown both by itself and superimposed on the LDRPot main board. The main board is 2.9 inches long by 1.3 inches tall.


« Last Edit: 14 Nov 2018, 02:25 am by tortugaranger »

WC

Re: LDRPot.V1 Stepped Attenuator
« Reply #1 on: 14 Nov 2018, 01:33 am »
Looks interesting. I might use this on a headphone amp instead of a pot.

happyrabbit

Re: LDRPot.V1 Stepped Attenuator
« Reply #2 on: 16 Nov 2018, 02:22 am »
thank you for sharing   :thumb:   

suggestion -   placement might be a bit easier if the encoder is cabled instead of mounted to the board..   just a thought.  ymmv

Dwight

tortugaranger

  • Facilitator
  • Posts: 1423
  • Handcrafted high performance audio gear
    • Tortuga Audio
Re: LDRPot.V1 Stepped Attenuator
« Reply #3 on: 16 Nov 2018, 01:33 pm »
thank you for sharing   :thumb:   

suggestion -   placement might be a bit easier if the encoder is cabled instead of mounted to the board..   just a thought.  ymmv

Dwight

What you're describing is essentially our existing LDR.V25 (the "V25") Preamp Controller which has to be mounted on standoffs with a cable connection to a separate panel mounted encoder. The V25 has input switching (up to 6 inputs) and built-in LDR calibration which the LDRPot does not have.

The idea behind the LDRPot is a smaller, simpler, lower cost option that conveniently mounts directly in a front panel and thus doesn't require a mounting space footprint on the enclosure floor.

tortugaranger

  • Facilitator
  • Posts: 1423
  • Handcrafted high performance audio gear
    • Tortuga Audio
Re: LDRPot.V1 Stepped Attenuator
« Reply #4 on: 27 Nov 2018, 03:46 pm »
We just got our first round of LDRPot prototype circuit boards. Here you see the smaller LDRPot Module board above the LDRPot Main board. The LDRPot Module board will plug into the LDRPot Main board. I included a US penny as a size reference (19 mm in diameter). The LDRPot Main board uses the same new design as our V3 Preamp Controller which is in parallel development. We'll be using a variation of the V3 as an in-house calibrator to calibrate the LDRPot Modules since the LDRPot Main board does not have its own built-in calibration.


WC

Re: LDRPot.V1 Stepped Attenuator
« Reply #5 on: 6 Dec 2018, 03:14 am »
So looking at the board, this looks like it is for unbalanced stereo connections only? Is there a way to use it with balanced connections?

tortugaranger

  • Facilitator
  • Posts: 1423
  • Handcrafted high performance audio gear
    • Tortuga Audio
Re: LDRPot.V1 Stepped Attenuator
« Reply #6 on: 6 Dec 2018, 03:20 pm »
So looking at the board, this looks like it is for unbalanced stereo connections only? Is there a way to use it with balanced connections?

You are correct in that the LDRPot board as shown is for unbalanced stereo.

As with our current LDR.V25 Preamp Controller, to implement balanced volume control you need 4 channels, or 2 boards, with one board acting as the primary control interface which communicates to the secondary board to keep them both in sync.

I fully expect the final LDRPot design to be configurable for balanced audio. That will require a 2nd LDRPot main board with its own 2 channel LDR module be attached to the underside of the primary LDRPot main board. The secondary board will need 4 connections to the primary board; power, ground and a 2 wire serial data link. I'm hopeful those can be made with a direct board-to-board pin link but worst case you end up with a 4 wire square pin cable connecting the 2. Of course the secondary board will have its own screw terminal header for its own 2 channel balanced signal.

We have a few iterations to go through before the LDRPot is ready for release. We are developing the LDR.V3 Preamp Controller in parallel with the LDRPot where the LDRPot will be a simplified variant of the LDR.V3.

happyrabbit

Re: LDRPot.V1 Stepped Attenuator
« Reply #7 on: 22 Jan 2019, 05:57 pm »
Any updates ?  Also what are the dimensions for the encoder shaft / mounting hole ? 

Thanks

Dwight   

tortugaranger

  • Facilitator
  • Posts: 1423
  • Handcrafted high performance audio gear
    • Tortuga Audio
Re: LDRPot.V1 Stepped Attenuator
« Reply #8 on: 22 Jan 2019, 07:52 pm »
Any updates ?  Also what are the dimensions for the encoder shaft / mounting hole ? 

Thanks

Dwight

The encoder shaft will require a nominal 0.3 inch diameter panel hole (could be a bit larger if you like) and the shaft is standard 6 mm. The panel hole size could change but not likely. Shaft size is fixed.

Development of the LDRPot is running in parallel with the LDR.V3 Preamp Controller. The V3 will become the de facto LDR Module programmer for the LDRPot's LDR Module. Both the V3 and the LDRPot will use the same plug-in LDR Module board. Unlike the V3, the LDRPot will not have its own built-in LDR calibration and it won't have input switching. Another key difference between the V3 and the LDRPot is the V3 will have an isolated control system ground whereas the LDRPot will not. The V3 is in its 4th or 5th prototype iteration and is hopefully close to the end of its development cycle. Once that's basically done, the LDRPot will follow closely behind the V3 since it will be a stripped down version of the V3.

tortugaranger

  • Facilitator
  • Posts: 1423
  • Handcrafted high performance audio gear
    • Tortuga Audio
Re: LDRPot.V1 Stepped Attenuator
« Reply #9 on: 13 Feb 2019, 04:50 pm »
I've been getting numerous inquiries regarding the status of the LDRPot so here's a short update.

The LDRPot and the V3 version of our preamp controller board are in parallel development. The LDRPot will effectively be a variant on the V3 with the key differences being: a) no built-in LDR calibration, b) no input switching, and; 3) an encoder mounted directly to the board itself. The LDRPot will be commensurately way smaller than the V3 board in keeping with its being mountable directly to a front panel just like a volume pot or conventional stepped attenuator.

The LDRPot and the V3 will share the same new plug-in 4-LDR module board. Thus the V3 will be the de facto calibrator board for the new 4-LDR module board used by the LDRPot.

We are several iterations deep on the V3 design (plus a couple deep on the LDRPot itself) with the latest V3 build board due back from fabricator later this month. Once the V3 design is complete it will be a short hop to finishing the LDRPot. Timing on all that is iffy but I'm thinking April/May is doable but I'm usually wrong when guessing on this stuff.

More info to follow as we  get closer to release.

Cheers,   :thumb:
Morten
« Last Edit: 21 Feb 2019, 09:21 pm by tortugaranger »

tortugaranger

  • Facilitator
  • Posts: 1423
  • Handcrafted high performance audio gear
    • Tortuga Audio
Re: LDRPot.V1 Stepped Attenuator
« Reply #10 on: 6 Jun 2019, 09:04 pm »
Wow. Where did the time go!!?? This week we inch ever closer to the launch of the LDRPot but first things first which means we need to finalize the design details of the V3 preamp controller. The latest V3 prototype boards arrived this week and over the next few days we'll be building and testing the latest V3 design iteration. There's a key go-nogo aspect to the V3 design that we need to get past and the latest iteration should get us past this development milestone. I sure hope so. It's been several month longer than I'd anticipated but what else is new....things take twice as long (or longer) and cost twice as much (or more!). Keep in mind that the V3 will be the LDR calibration board for the 4-LDR plug-in LDR module used by both the V3 and the LDRPot. Hence the road to the LDRPot goes right through the V3. Road trip!!!  :thumb: