[justubes]

 Have changed out previously all ldrs with new one, same issue.

Seems that my autocal is not completing the whole cycle which i wrote to you before and havent since  tried to touch in fear it become unusable meaning no more music  and dont want the downtime.

I have not gathered courage to do the firmware update as it means i have to run autocal all over again?

[tortugaranger]

Have changed out previously all ldrs with new one, same issue.

Seems that my autocal is not completing the whole cycle which i wrote to you before and havent since  tried to touch in fear it become unusable meaning no more music  and dont want the downtime.

I have not gathered courage to do the firmware update as it means i have to run autocal all over again?

LOL. I never thought updating firmware would require courage! I realize I have a different perspective on this given my familiarity with the inner workings of everything but I literally load/update firmware into our boards on almost a daily basis. It's a highly mature process which just works once you have everything set up.

More recent firmware update work specifically addressed a few lingering issues when using our controller boards in a balanced (master/slave) configuration. For this reason I would encourage updating the firmware on balanced setups especially.

Moreover, running autocal isn't some kind of iffy process that anyone should be afraid of. As long as your LDRs are healthy it just works. If they're not healthy...well, you should find that out and replace them accordingly. Autocal helps in this process. Again, if you have noticeable channel imbalance after changing impedance settings, you definitely need to rerun autocal. My recommendation is   - just do it! 

[tortugaranger]

Upcoming Changes to Adjustable Impedance in V25 Based Preamps

Appreciate any inputs from users on this topic.

The Problem: The adjustable impedance feature currently allows users to unwittingly select an impedance setting (1 thru 5) and level (1k  thru 99k) which has not been properly initialized (has not been through a calibration cycle). This will result in no audio output because the user will have selected an impedance setting/level which has an empty attenuation table. The classic symptom is no audio output or very low audio output that doesn't respond to volume changes. Users get justifiably confused/concerned and wonder why their preamp isn't working. I get emails and phone calls.

The Fix: Firmware update/change which:
a) Will cause the displayed impedance setting/level to blink indicating that the setting/level has not been initialized (has not been run through calibration).
b) Will not allow preamp to switch to a setting/level that is not initialized as evidence by blinking display. 
c) Will leave setting #1 fixed @ 20k as the permanent default. User can rerun calibration of this default setting/level at any time but can't change the impedance level of #1.
d) Will revert to default #1 @ 20k, or, to last known valid initialized setting #/level if user makes a change to impedance setting #/level and does not then immediately thereafter initialize this change by running the preamp through a calibration cycle. 

To summarize this in as simple language as possible, after this firmware change, when you scroll through impedance settings #2 thru 5, if the display blinks those settings are not initialized and therefore the preamp won't switch to any blinking setting. Setting #1 at 20k will never blink because it's the default and user can't change its level. If you do want to use settings 2 thru 5 or change the level of any of these setting #'s you have to run autocal immediately after selecting/changing them or else they will remain un-initialized.

[kernelbob]

Hi Morten,

I'm so glad your back, safe and sound.

Regarding setting impedance setting #1 permanently to 20k, I really hope you can avoid this.  I use all five of the available saved settings and 20k isn't even in the ballpark.  I'm using the Lampizator Golden Gate DAC.  I'm able to fine tune the voicing of the DAC for different recordings by selecting between my various saved impedance settings.

Currently, I have my LDRxB's five impedance settings at 85, 88, 91, 94, 97k.  Those are of course per phase on each leg of a balanced input.  Even at that, it would be great to have more available saved settings.  Now that you have more available memory in your logic system, could you have 10 settings identified as 0 through 9 with 0 being a fixed value?

Best,
Robert

[kernelbob]

justubes, if you have the feature where the display goes dark after a period of time, make sure that you disable that (set the delay time to 0) before setting an impedance level.  I occasionally forget to do that and run an impedance change.  The first time that I did that, I thought the calibration cycle had finished and brought the system back up.  Just a thought.

Best,
Robert

[tortugaranger]

....it would be great to have more available saved settings.  Now that you have more available memory in your logic system, could you have 10 settings identified as 0 through 9 with 0 being a fixed value?

Since I'm modifying this code right now anyway expanding from 5 to 10 settings is fairly straightforward. Setting #1 will remain fixed at 20k and the other 2-10 are all adjustable. Once these changes have been tested all new V25 units will shipped with the changes outlined.

[kernelbob]

Hi Morten,

It's like you've got a magic wand.  More than once, when I've suggested something, it just happens!  I did want to reiterate to anyone shopping for a controller that I've come to really value the adjustable input impedance feature.  Having lived with three DACs with the LDRxB-V2 (and tried others with it), I would not want to use any other controller that lacked this feature.  The Lampizator Golden Gate was especially responsive to different input impedances which I now use to voice the sound for specific recordings.  Even a change of a few kohms is audible.

Now, if there were just some way to move/copy an impedance setting from one saved slot number to another to avoid having to do recalibrations to reorder the impedance slots...

Best,
Robert

[tortugaranger]

Now, if there were just some way to move/copy an impedance setting from one saved slot number to another to avoid having to do recalibrations to reorder the impedance slots...

That's doable but would add a level of additional complexity to the code that would take a fair bit of additional time to implement and test. I simply don't have the time for that right now but will put it on the wish list. 

[tortugaranger]

Upcoming Changes to Adjustable Impedance in V25 Based Preamps

I've completed the software mods and will be posting an updated V25 firmware file soon for those interested in uploading this change to their V25 based preamp. 

Here's an update on how things turned out.

The Problem: The adjustable impedance feature currently allows users to unwittingly select an impedance setting (1 thru 5) and level (1k  thru 99k) which has not been properly initialized (has not been through a calibration cycle). This will result in no audio output because the user will have selected an impedance setting/level which has an empty attenuation table. The classic symptom is no audio output or very low audio output that doesn't respond to volume changes. Users get justifiably confused/concerned and wonder why their preamp isn't working. I get emails and phone calls.

The Fix: Firmware update (rev 1012) as follows:
a) Possible impedance settings has been increased from 5 to 10.
b) Each setting 2 thru 10 can be adjusted by user to be between 1k and 99k.
c) Setting #1 is now fixed at the level of 20k and this level cannot be changed by user.
d) In the event user makes a change to an impedance setting level and forgets to subsequently run autocal to build the attenuation table for that setting/level the preamp will not ignore that setting/level and next time the unit is turned on it will use either the default setting #1/20k or the most recent other valid impedance setting/level if there is one.
e) If the user switches the preamp to an impedance setting/level that has not been initialized (run through autocal) the display will blink and there won't be any audio output.
f) If the user becomes confused, just turn the preamp off and back on again and it will resume operating at the last known valid impedance setting/level.

All preamps shipped on/after Sept 16, 2017 will already incorporate this firmware change.

It's worth noting that the adjustable impedance feature of the V25 is entirely optional. If you never make a change the preamp will use the default setting #1 fixed at 20k input impedance.

[NoellEagan]

Hi...i am a new user here. As per my knowledge I did reverse the channels to determine if it was a weak channel in my little digital amp but no difference was detected. I did do this with music, not test tones. Is a 6 pts. adjustment significant?Is there a breaking period in which the LDRs' equalize?

[tortugaranger]

Hi...i am a new user here. As per my knowledge I did reverse the channels to determine if it was a weak channel in my little digital amp but no difference was detected. I did do this with music, not test tones. Is a 6 pts. adjustment significant?Is there a breaking period in which the LDRs' equalize?

Hi Noel,
What model/hardware/firmware version are you working with?
By "6 pts" do you mean you adjusted channel balance by 6 steps to center the balance?
Did you run autocal? If not, please do and note any change.
Best,
Morten

[TheMonkey]

Hi Morten!

I have been keeping an eye on the Firmware Updates section under the support-section for a while but completely missed out on this thread...
Good news about the rev1012, been looking forward to this!! 

I'm really eager to update, when do you intend to upload the new firmware or did I miss it somewhere?

Many Thanks!
/ Simon 

[tortugaranger]

Hi Morten!

I have been keeping an eye on the Firmware Updates section under the support-section for a while but completely missed out on this thread...
Good news about the rev1012, been looking forward to this!! 

I'm really eager to update, when do you intend to upload the new firmware or did I miss it somewhere?

Many Thanks!
/ Simon

I've been letting these changes "mature" a bit since it represents a major update to the adjustable impedance code. It seems to be stable at this point so I'll be updating the firmware/download on the website this week.

The first time your preamp runs with this new version of firmware, it will go through a fairly long reset process that will rewrite/reinitialize all the impedance settings and related attenuation tables. This takes several minutes during which time the master board (in a balanced system) will display numbers as it goes along. When this is done with slave boards in the system there's no status info displayed/available so make sure to just leave the unit alone for 10 minutes after uploading the update to the slave board which is the second board in a balanced system which is usually connected to the lower of the 2 USB ports on the rear panel.

Once both boards are updated, run calibration again for the default setting #1/20k. Setting #1/20k will now be fixed and can no longer be changed. Only settings #2-10 can be changed by the user after this update.

[Tubeburner]

Morten, are you saying I should run autocal for each 1-10  impedance or can I put in all 9 new impedance and then run autocal?

[tortugaranger]

Morten, are you saying I should run autocal for each 1-10  impedance or can I put in all 9 new impedance and then run autocal?

Each has to handled separately one at a time. Select a setting #, change the level, press Enter button on remote. Then immediately run Autocal to initialize that new setting/level. Rinse, repeat for other setting # changes.

Changing or setting up a new impedance setting has always required this process. This is not a new procedure.

[Tubeburner]

I don't see in the v25 instructions on your website where it says to run Autocal after each impedance setting.

[tortugaranger]

I don't see in the v25 instructions on your website where it says to run Autocal after each impedance setting.

The info is available in the online Product Documentation found via this link:  https://www.tortugaaudio.com/support/product-documentation/

It can be found under General Information -> Preamp Characteristics & Features -> Adjustable Impedance -> How To Set Up Each Impedance Setting

Under this subheading you'll find detailed information on how to set up each impedance setting.

There's a specifically highlighted paragraph which I've copied below that states quite clearly that each setting/level has be set up individually. I need to update this to reflect that the lates V25 firmware now has up to 10 settings but otherwise this generally applies to all models and firmware versions and has not changed materially since adjustable impedance was first introduced.

Changing the impedance level of a given impedance setting number (1-5) must be done for each impedance setting individually per the steps below. For example, this means you have to follow the entire procedure listed below for impedance setting #2 and only #2. Once you’ve completed the procedure for #2, you can then choose to change the impedance for some other impedance setting number. If you wish all 5 settings to be available, you must setup each setting number separately.

The final key step is always to run autocalibration as the final step before initiating or editing another setting #.

[TheMonkey]

Hi Morten!

I just wanted to say I'm still looking forward to the rev1012 update  . I hope you find some time to upload it.
Thanks!
/ Simon

[tortugaranger]

Hi Morten!

I just wanted to say I'm still looking forward to the rev1012 update  . I hope you find some time to upload it.
Thanks!
/ Simon

It's available now. Rev 1015. Please read the notes before proceeding.

[tortugaranger]

A new version of the firmware (Rev 1015) is now available for V25 board/preamp users.
This update is only relevant to users who current have version 1011 or older.
This update makes numerous changes to how adjustable impedance is handled.
Info on this update can be found in the online documentation via this link:  https://www.tortugaaudio.com/support/product-documentation/
Go to section:  General Information -> Firmware Updates -> V25 Firmware

The details are repeated here:

Release 1012 represents a major change to how adjustable impedance is handled. Upgrading to 1012 will cause your preamp to erase and reset all existing impedance settings and calibration data followed by automatically running calibration at the new fixed default of setting #1 @ 20k. The update will not be completed until this calibration step is completed. Please allow up to 15 minutes to allow the updating, reseting and calibration process to complete. The unit will reboot and restart after completion. Try not to turn of power or otherwise interrupt this process or else it will repeat from the beginning until allowed to fully complete.

** Changes with 1012 **
1) Impedance settings increased from 5 to 10.
2) Impedance setting #1 is now fixed at the default of 20k and can no longer be changed by user. Only settings 2-10 can be setup and modified by user.
3) The display will now blink when user selects an impedance setting number and level combination that has not already been run through calibration.
4) Switching the unit to any setting/level combination that is not calibrated will result in no output from the preamp.
5) Changing an impedance setting/level will not be saved or go into effect until after calibration is run. Press the Enter/Center button on remote after completing a change and then proceed to run calibration as the next step.  It's up to the user to ensure calibration is run as the final step. If calibration is not run immediately after making a setting/level change, the unit will revert to last known valid setting/level. If no other settings/levels have been configured the unit will revert to default #1/20k.
6) As before, each setting/level change must be done individually and then processed through calibration to become effective and/or available. User can not make multiple simultaneous changes to settings/levels and run them all through calibration together.