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[LDD-1] AC-3 Unit - just curious
https://forum.lddb.com/viewtopic.php?f=24&t=8278
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Author:  je280 [ 13 Feb 2019, 00:42 ]
Post subject:  [LDD-1] AC-3 Unit - just curious

Looking at images of the LEXICON AC3-RF LDD-1 demodulator I see a three way toggle switch on the front marked LD OPTIMIZATION: HIGH - LOW - NORMAL

I had a YAMAHA unit quite a while ago & it was simply plug it in & that was it.

Just curious here but what would the HIGH - LOW - NORMAL : LD OPTIMIZATION switch actually do on this unit?

Cheers

Author:  admin [ 13 Feb 2019, 01:02 ]
Post subject:  Re: Lexicon LDD-1 AC-3 Unit - just curious

It was supposed to be optimized based on the players, you can check the documentation on page 4/8 here:

http://manuals.lddb.com/AC3RF_Demodulators/Lexicon_LDD-1-EN.pdf

Julien

Author:  je280 [ 13 Feb 2019, 02:36 ]
Post subject:  Re: Lexicon LDD-1 AC-3 Unit - just curious

Thank-you Julien :thumbup:

Author:  ldfan [ 15 Feb 2019, 03:48 ]
Post subject:  Re: Lexicon LDD-1 AC-3 Unit - just curious

admin wrote:
It was supposed to be optimized based on the players

Julien


Hmmm....wonder if they mean the voltage level of the AC3-RF signal since it can vary from 3.6 to 4.5 volts? Or maybe something different. :?:

Author:  miskia [ 25 Apr 2019, 19:49 ]
Post subject:  Re: Lexicon LDD-1 AC-3 Unit - just curious

I ordered a LDD-1 few days ago, approximative 150€, less than some Yamaha demod I saw, but this one have the "auto switch" I was looking for (like the Pioneer RFD-1).
But I already opened the beast... :lol:

I need a Toslink optical SPDIF output, so I'll modify the PCB to add this functionnality.
I'd like to have an internal 230V power supply and also modify the "control" fonctionnality to have a 12V trigger in a minijack to power the beast with my AVR 12V trigger output. :)

I'll probably put the circuit in an other box than the original rack mounting one.

Just need some times

Author:  admin [ 20 Apr 2021, 11:03 ]
Post subject:  Re: Lexicon LDD-1 AC-3 Unit - just curious

miskia wrote:
Just need some times


Did you ever customize your LDD-1?

I'd be interested in the 12V trigger (using pin 2 GND and pin 3 Trigger of the PWR CTRL DIN?).

Julien

Author:  admin [ 27 May 2021, 13:06 ]
Post subject:  Re: Lexicon LDD-1 AC-3 Unit - just curious

I tried to get the LDD-1 trigger to work with a standard 0/+12V trigger but... so far no luck.

Of course at 12V, the unit is up.
But at 0V it won't power off.

You need to short signal to GND to make it power off, not a standard trigger :-(

You would expect:

0V => OFF
12V => ON

But it's:

Shorted => OFF
Any voltage => ON

Julien

Author:  drewmanfu0 [ 31 May 2021, 05:10 ]
Post subject:  Re: Lexicon LDD-1 AC-3 Unit - just curious

Julien,

If 0v is present on the DIN connection you can use a standard 5 pin automotive relay to trigger the unit. Pin 30 of relay to din "sense" input. 87 would have "any voltage" and 87a would be 0v. Terminals 85 and 86 would be wired to your receiver 12v trigger.

Author:  admin [ 31 May 2021, 05:19 ]
Post subject:  Re: Lexicon LDD-1 AC-3 Unit - just curious

I actually contacted Lexicon to ask for more wiring details and it seems that the problem is coming from the GND.

The cable I got from eBay splits the DIN5 into 2 mono mini-jacks as follows:

Pin 2 for GND + Pin 3 for Tip
Pin 2 for GND + Pin 5 for Tip

From Lexicon diagram, they expect GND on Pin 1 and Power 12V trigger on Pin 3.

https://manuals.lddb.com/AC3RF_Demodulators/Lexicon_LDD-1-EN-DC_Trigger_Cable_Mini_to_DIN_cable.pdf

I will connect Pin 1 with Pin 2 (and Pin 4 along the way since it's not connected to anything) and get them all to GND.
I just don't have a piece of electrical wire to use/test this right now.

Julien

Author:  jakeheke [ 31 May 2021, 08:26 ]
Post subject:  Re: Lexicon LDD-1 AC-3 Unit - just curious

Curious about the original question here,
What actually is the difference between those settings? Voltage or?
I read the manual that suggests some models for each usage, do players pump out AC3RF differently?

Author:  ldfan [ 02 Jun 2021, 04:42 ]
Post subject:  Re: Lexicon LDD-1 AC-3 Unit - just curious

I was hoping someone would chime in as well and provide a definitive answer.

My initial guess was different voltage levels but after reading the manual for this unit and the JBL version (basically the same) it appears the switch is about adjusting timing. Thus, it appears that Lexicon did believe that different aftermarket AC3-RF mods could speed up or slow down the signal coming out of the RCA jack ("normal" setting is always for factory made AC3-RF outputs).

I don't know how much of this really can be heard and I assume it was not viewed as a huge issue seeing that all the other AC3-RF Demodulators out there never incorporated anything similar. Also, most of the players I use in my set-ups use the aftermarket AC-3 mods and I have never noticed any lip sync issues ever.

I guess the only way to evaluate it would be to try it out in all three settings on different players. My guess would be nothing really discernable but who knows.

Author:  dennish [ 18 Feb 2022, 00:14 ]
Post subject:  Re: Lexicon LDD-1 AC-3 Unit - just curious

I run my LDD-1 in Normal and as for power off I have a power strip with an off switch and just turn that off when I'm not using the LD Player. Going to use the same power strip for my iScam VP-50 Pro I just bought. No point in keeping power supplies powered up when they are not being used and some of these are hard to replace (VP-50 being one of them).

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