LDRPot.V1 Stepped Attenuator

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tortugaranger

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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

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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

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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

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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.