LDR.V25 (the "V25") Preamp Controller

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tortugaranger

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Re: LDR.V25 (the "V25") Preamp Controller
« Reply #80 on: 13 Jun 2017, 11:41 am »
Hi Morten,

Well received the boards and waiting for the new enclosure.

I got two questions thou. Is there a reason to have the USB 5 pins header solder on back side of the board? I'm a little bit confused as it is riding over the solder pads of J9. Also what is the usage of the 10 pins header on the back side, right underneath the processor chip. It is not mentioned in documentation and it seems kind of bad soldered.

The 90 degree J8 USB pin header is on the underside with a side entry to avoid interference other headers topside. With ribbon cables plugged into both J3 and J9 there's little or no room to connect to J8 topside. There's sufficient clearance from the J9 solder pads to not impede the functioning of J9 and if by chance the J8 is touching one of the J9 legs it's because it wasn't tilted down properly when installed in which case it's a simple matter to slightly bend the J8 pins down to clear J9.

The 10 pin connection on the underside is there solely to initially program the processor bootloader and is not used thereafter. Eventually we'll elimante this connector by pre-programming the chips before install. Firmware loading/updating is done via USB.
« Last Edit: 13 Jun 2017, 01:40 pm by tortugaranger »

TheMonkey

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Re: LDR.V25 (the "V25") Preamp Controller
« Reply #81 on: 17 Jun 2017, 11:21 pm »
Hello Morten!

My enclosure from Hifi2000 arrived yesterday so I have been building almost nonstop since then on my balanced V25s. I have been trying to avoid all wiring mistakes and I have double checked everything before powering on. To my relief, no magic smoke, it powered up fine! :) It was good guidance in the support documentation!

However before testing, I would like to upgrade to the latest firmware. I have been trying soooo many times now without being able to connect. I've been following the instructions and I understand that 5 sec gap but still no success. I have tried both in Linux (running the bootloader in an emulator with full privileges) and also from a laptop with Windows 10 (both as standard user and administrator). It just keeps saying the same thing: "Unable to find device: USB HID Bootloader." I have tried both the Master and the Slave board.

Am I missing something?

Many thanks!
/ Simon

tortugaranger

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Re: LDR.V25 (the "V25") Preamp Controller
« Reply #82 on: 18 Jun 2017, 11:50 am »
Hello Morten!

My enclosure from Hifi2000 arrived yesterday so I have been building almost nonstop since then on my balanced V25s. I have been trying to avoid all wiring mistakes and I have double checked everything before powering on. To my relief, no magic smoke, it powered up fine! :) It was good guidance in the support documentation!

However before testing, I would like to upgrade to the latest firmware. I have been trying soooo many times now without being able to connect. I've been following the instructions and I understand that 5 sec gap but still no success. I have tried both in Linux (running the bootloader in an emulator with full privileges) and also from a laptop with Windows 10 (both as standard user and administrator). It just keeps saying the same thing: "Unable to find device: USB HID Bootloader." I have tried both the Master and the Slave board.

Am I missing something?

Many thanks!
/ Simon

Hi Simon,

First, be assured that the firmware bootloader process/system works flawlessly when set up and executed properly. I do this practically every day with our preamp boards. It's how the boards you have were programmed. It's worked fine for me under Windows7, 8 and now 10.

The #1 most likely reason you're having this problem is with the USB cable you are using. More and more USB cables today are really not data cables but are essentially 5V power charging cables for various digital devices like cell phones etc. I've not taken one of those cables apart to see for myself but apparently they lack one or both of the D+ and D- USB data lines.

Other customers have had this problem and after getting a proper USB cable the firmware bootloader worked as it should.

A way less likely cause is if you have a USB port monitoring program running on your PC that could be interfering. I've not run into this with our preamp boards but it's been reported by others using similar bootloader tools. One program cited was Advanced USB Port Monitor. After turning it off the USB monitor or removing it from their PC, the bootloader worked fine.

I suggest you try a different cable and see how it goes.

Best,
Morten

TheMonkey

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Re: LDR.V25 (the "V25") Preamp Controller
« Reply #83 on: 18 Jun 2017, 05:07 pm »
Thank you Morten!

I already suspected the cable might be the one causing problems because I've had previous bad experiences before. Since it was the cable from the kit I thought it was tested, plus that I didn't have any other USB-A male to male to try with. I just bought a really short (to be on the safe side) USB.3 cable and now it works!!  :D

Some other questions:
I think I read somewhere that the autocal is running in the background?
If I adjust the impedance it has to run through autocal to work, right?
I have tried to start it manually according to the info in the support pages but display stays off no matter what I try :(

TheMonkey

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Re: LDR.V25 (the "V25") Preamp Controller
« Reply #84 on: 18 Jun 2017, 05:22 pm »
Haha, now I have f**ked it up completely. Now even the first "1   20" setting won't work any more, just some white noise.  :duh: :scratch:

tortugaranger

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Re: LDR.V25 (the "V25") Preamp Controller
« Reply #85 on: 18 Jun 2017, 06:46 pm »
Thank you Morten!

I already suspected the cable might be the one causing problems because I've had previous bad experiences before. Since it was the cable from the kit I thought it was tested, plus that I didn't have any other USB-A male to male to try with. I just bought a really short (to be on the safe side) USB.3 cable and now it works!!  :D

Glad to hear you got the firmware update working. So many USB cables theses days are just charging cables and not actual USB data cables.

Quote
Some other questions:
I think I read somewhere that the autocal is running in the background?

Not yet. That's something that will be introduced in a future version of the firmware. For now, you have to start it manually.

Quote
If I adjust the impedance it has to run through autocal to work, right?
I have tried to start it manually according to the info in the support pages but display stays off no matter what I try :(

Yes, after making changes to impedance setting number and/or level you have to rerun autocal for those changes to become effective.
If the displays stay off, you have not started autocal.

With the V25 it's a bit different than the V2. You first have to turn the unit on, then press the mode button 5 times to get it to autocal mode, then press the right button 3 times to start.

tortugaranger

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Re: LDR.V25 (the "V25") Preamp Controller
« Reply #86 on: 18 Jun 2017, 06:52 pm »
Haha, now I have f**ked it up completely. Now even the first "1   20" setting won't work any more, just some white noise.  :duh: :scratch:

With kits the #1 mistake people make is not properly grounding the audio signals. The left and right side signal grounds must both be connected to star ground point for autocal to work properly. You can't calibrate the LDRs without a reference to ground.




TheMonkey

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Re: LDR.V25 (the "V25") Preamp Controller
« Reply #87 on: 18 Jun 2017, 08:53 pm »
Thanks for a good and rapid reply!

Good that you updated the firmware section with some cable info. It's probably better not to send a cable with the kit than to get that bad one I got. 

I was wondering what that 5th control mode was with the two zeroes!!  :D

Star ground was already sorted. I must admit that at first, I did feel a little uncertain to connect the ground from the PSU though!
Problem solved, I had just missed that the autocal was working differently on the V25. I did try my best to seek the answer in the documentation but couldn't find any info about that 5th control mode... Thanks for clearing that up!  :thumb:
(seems like a better way to do it than the old way anyway.)

I got two pairs of XLR inputs and two pairs of XLR outputs and I thought that was minimalistic until I did the wiring. It was not that difficult, it's just a lot more cables than you first think!!
All the "1" to star ground (didn't daisy-chain), all "2" to Master, all "3" to Slave was really straight forward! Otherwise I would have had to mark the cables to not mess up. 
Anyway, I used the Neotech 26AWG solid copper cable you recommended, nice cable but if you are using short lengths it's easy that you'll just move the whole sheet when stripping them.

Autocal seems to be running fine now. I have managed to save 3 presets but when trying to save the 4th It just keeps erasing it. Do they have to be in rising order? (like 10, 20, 30, 40 instead of mixed?) Any other ideas?
I have been trying with a complete restart as well btw. It sometimes says "4   1" instead of "0   0" in the 5th control mode if that's any help.

The next few days I'm gonna be up for some serious listening!!  :D
/ Simon

TheMonkey

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Re: LDR.V25 (the "V25") Preamp Controller
« Reply #88 on: 20 Jun 2017, 06:36 pm »
It finishes autocal without any problems. It does say "4   1" in the fifth control mode afterward sometimes which I don't understand. First I thought it might not have finished the fourth check but I've been watching it and it seems to finish all checks just fine. It goes away after a restart/killing the power though and goes back to "0   0". Does this mean anything? A faulty LDR? A badly grounded cable?

Many thanks!
/ Simon

tortugaranger

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Re: LDR.V25 (the "V25") Preamp Controller
« Reply #89 on: 20 Jun 2017, 07:45 pm »
It finishes autocal without any problems. It does say "4   1" in the fifth control mode afterward sometimes which I don't understand. First I thought it might not have finished the fourth check but I've been watching it and it seems to finish all checks just fine. It goes away after a restart/killing the power though and goes back to "0   0". Does this mean anything? A faulty LDR? A badly grounded cable?

Many thanks!
/ Simon

No, that's "normal" but will be removed in next firmware build. It should reset to 0/0 but doesn't mean anything.

enser

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Re: LDR.V25 (the "V25") Preamp Controller
« Reply #90 on: 26 Jun 2017, 07:35 pm »
On the question of daisy chaining-

For a four v25 board configuration, would I go about daisy chaining the boards as (?) :

Master (tx1, rx1) -> Slave 1 (rx2, tx2)
Slave 1 (tx1, rx1) -> Slave 2 (rx2, tx2)
Slave 2 (tx1, rx1) -> Slave 3 (rx2, tx2)

Or would it more of a hub and spoke with a loop back connection from the last slave like:

Master (tx1) -> Slave 1 (rx2)
Master (tx1) -> Slave 2 (rx2)
Master (tx1, rx1) -> Slave 3 (rx2, tx2)

Or hub and spoke with loopback from each slave to the master like:

Master (tx1, rx1) -> Slave 1 (rx2, tx2)
Master (tx1, rx1) -> Salve 2 (rx2, tx2)
Master (tx1, rx1) -> Slave 3 (rx2, tx2)

This is with the latest FW. I would only be connecting DM1 master/slave module + encoder + ir rx to Master board.
The goal is to have the master handle volume and input selection control for 4 single ended stereo channels. For 2 inputs, I would populate every board with LDRs appropriately.

tortugaranger

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Re: LDR.V25 (the "V25") Preamp Controller
« Reply #91 on: 27 Jun 2017, 02:13 am »
On the question of daisy chaining-

For a four v25 board configuration, would I go about daisy chaining the boards as (?) :

Master (tx1, rx1) -> Slave 1 (rx2, tx2)
Slave 1 (tx1, rx1) -> Slave 2 (rx2, tx2)
Slave 2 (tx1, rx1) -> Slave 3 (rx2, tx2)

Or would it more of a hub and spoke with a loop back connection from the last slave like:

Master (tx1) -> Slave 1 (rx2)
Master (tx1) -> Slave 2 (rx2)
Master (tx1, rx1) -> Slave 3 (rx2, tx2)

Or hub and spoke with loopback from each slave to the master like:

Master (tx1, rx1) -> Slave 1 (rx2, tx2)
Master (tx1, rx1) -> Salve 2 (rx2, tx2)
Master (tx1, rx1) -> Slave 3 (rx2, tx2)

This is with the latest FW. I would only be connecting DM1 master/slave module + encoder + ir rx to Master board.
The goal is to have the master handle volume and input selection control for 4 single ended stereo channels. For 2 inputs, I would populate every board with LDRs appropriately.


This is the way to go with the multi-channel daisy-chain of V25 boards.

Master (tx1, rx1) -> Slave 1 (rx2, tx2)
Slave 1 (tx1, rx1) -> Slave 2 (rx2, tx2)
Slave 2 (tx1, rx1) -> Slave 3 (rx2, tx2)

enser

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Re: LDR.V25 (the "V25") Preamp Controller
« Reply #92 on: 28 Jun 2017, 07:26 pm »
Thanks Morten- looking forward to getting the multichannel LDR passive going!  :thumb:

tortugaranger

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Re: LDR.V25 (the "V25") Preamp Controller
« Reply #93 on: 28 Jun 2017, 08:40 pm »
Thanks Morten- looking forward to getting the multichannel LDR passive going!  :thumb:


New boards on their way. I expect you'll have them for the weekend.

enser

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Re: LDR.V25 (the "V25") Preamp Controller
« Reply #94 on: 6 Jul 2017, 07:00 pm »
Hey Morten,

How do you go about switching absolute polarity/phase with v25 in a balanced config?

tortugaranger

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Re: LDR.V25 (the "V25") Preamp Controller
« Reply #95 on: 6 Jul 2017, 07:08 pm »
Hey Morten,

How do you go about switching absolute polarity/phase with v25 in a balanced config?


You would dedicate 2 inputs to the same balanced signal but swap the phases when wiring up the second input. You would then fast-switch the input between the 2. If you used say inputs #4 and 5 you'd switch back and forth between them while listening to music to discern which sounds better.

enser

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Re: LDR.V25 (the "V25") Preamp Controller
« Reply #96 on: 6 Jul 2017, 08:54 pm »
Ah yes, that will work well. Thanks again- the balanced v25s sound great btw.  :thumb:

WC

Re: LDR.V25 (the "V25") Preamp Controller
« Reply #97 on: 7 Jul 2017, 02:01 am »
Morten,

With a balanced build with 2 boards, can you have some inputs balanced and some unbalanced? There was a comment in the v25 specifications on the website that seemed to imply that the balanced and unbalanced inputs could be combined with a two board build. I could see how it would work on the inputs, but I was kind of curious how that would work with the outputs. Would you be able to have only balanced outputs?

tortugaranger

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Re: LDR.V25 (the "V25") Preamp Controller
« Reply #98 on: 7 Jul 2017, 01:25 pm »
Morten,

With a balanced build with 2 boards, can you have some inputs balanced and some unbalanced? There was a comment in the v25 specifications on the website that seemed to imply that the balanced and unbalanced inputs could be combined with a two board build. I could see how it would work on the inputs, but I was kind of curious how that would work with the outputs. Would you be able to have only balanced outputs?

Yes, with dual boards you can mix balanced and single-ended inputs.

It gets a bit messy to explain/show but with balanced signals the master board handles the + phase for both the right/left channels and similarly the slave board handles the - phase for both channels. This arrangement is necessary in order for the channel balance adjustment feature to work properly.

To add single-ended inputs you would would only connect inputs to the master board's right/left channels.

The output wiring follows the same approach as the inputs. When a balanced input is selected that attenuated signal would also be present on the RCA output jacks but only from a single phase so the volume would be reduced. When a single-ended input is selected the balanced output would have a signal present on only one phase.

V25 Balanced Wiring


V25 Single-Ended Wiring

TheMonkey

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Re: LDR.V25 (the "V25") Preamp Controller
« Reply #99 on: 12 Jul 2017, 06:19 pm »
Hi Morten!

I'm still having problems with the impedance adjustment and my DAC and power amp are quite picky so I would really like to be able to switch between all 5 settings. Setting 1-3 is no problem but setting 4 seems to "erase" itself after finishing autocal so it goes back to 99.
Any ideas?      :scratch:

Also, how come you advised me not to buy the internal PSU for my balanced configuration and now you are using it in the new amps or is it a different new PSU? http://www.audiocircle.com/index.php?topic=151395.0
 
Many thanks!
/ Simon