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Calibration | V2 Pr…
 
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Calibration | V2 Preamp Controller  

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Posts: 7
Customer
(@germamiga)
Member
Joined: 5 years ago

Hello,
I have had an LDR3x.V2.1 Passive Preamp Controller for 5 years
but I have concerns about imbalance.
who knows the procedure to make a “recalibration” with the resistances?
thank you

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19 Replies
Posts: 24
Admin
(@morten)
Member
Joined: 9 years ago

The procedure to start calibration with the V2 model preamp controller is to press the Center button on the remote while the controller is turned off. The LDR number will be shown on the left 2-digit display while the calibration step number will be shown on the right 2-digit display. Calibration will still work even if you don’t have a display but it’s very difficult to tell what’s happening. If the channel imbalance is due to an LDR having drifted then running calibration should correct this. If the calibration process does not complete (gets stuck part way through) that’s an indication one of the LDRs needs to be replaced. 

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Posts: 7
Customer
(@germamiga)
Member
Joined: 5 years ago

Thank you for your reply !
but I misspoke.
indeed I had a faulty ldr, I changed it.
I was talking about pre-calibration!
on the site there was a module to position in place of the ldr to do this.
but where to find it? or is there a procedure?
thank you

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1 Reply
Admin
(@morten)
Joined: 9 years ago

Member
Posts: 24

@germamiga  Precalibration is intended to be a one-time only procedure to normalize all the hardware to a few known resistance levels. Something we do here in our shop as part of commissioning new controllers. I really don’t want to encourage anyone to do this because it is too easy  to make mistakes and once you’ve messed up the precal factors nothing else will work right until they are made right. So my question is why do you think you need to do this? 

 

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Posts: 7
Customer
(@germamiga)
Member
Joined: 5 years ago

yes i understand the question.
well, i have two v2.1 xlr cards.
I tested a transistor preamp, and I don’t have “this imbalance” that I have with the LDR preamp.
for example I have to do +4 on the right.
not with the transsistor preamp.
the voices are centered, but I have the impression of an imbalance with the instruments, which seem to me only on one side!
I changed 4 ldr to be sure.
and of course I recalibrated each time, testing by plugging the outputs, unplugging, ect …… 10 / 20 / 30 /40 /50 impedance.
so can there be a difference between the two cards?

but I’m ready to send it to you for verification!

cordially

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1 Reply
Admin
(@morten)
Joined: 9 years ago

Member
Posts: 24

@germamiga  It’s possible the 2 boards are not normalized to the same output level and it’s also possible that re-running precal on both boards might improve or eliminate that imbalance altogether. Or just use the +4 channel balance correction as you’re doing now which accomplishes the same thing except you have to convince yourself not to be annoyed with that adjustment staring you in the face 😉  Or you can send the boards back and we’ll rerun precal on them. Or finally I can provide you the detailed instructions to do this yourself. 

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Posts: 7
Customer
(@germamiga)
Member
Joined: 5 years ago

hello, and thank you for your help.
well as I have this imbalance, it persuades me that there is a problem.
therefore, I am not serene.
so if you want to give me procedure? I only have a display.
I think it’s better to have two displays?

I can test, and if I can’t, then will you send back the two cards only?

thank you

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1 Reply
Admin
(@morten)
Joined: 9 years ago

Member
Posts: 24

@germamiga  Here is a link to the V2 Precalibration procedure. We are in the process of rewriting and reorganizing our online documentation so this link isn’t yet published on our website. Once you’ve looked this over you can decide how you wish to proceed. We would need your 2 V2.1 boards and your Apple remote to do this procedure here in our shop.  https://www.tortugaaudio.com/docs/v2-precalibration/

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