LDR.V25 (the "V25") Preamp Controller

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robertopisa

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Re: LDR.V25 (the "V25") Preamp Controller
« Reply #60 on: 2 May 2017, 09:18 am »
I stay tuned for the upgrade from v2.0, I have two boards for balanced configuration.

Cheers
Roberto

While I've yet to announce any upgrade program, the key points that come to mind in considering an upgrade from a V2 to a V25 are as listed below. I'm sure this list will evolve.

1) Both boards use the same Tortuga Audio display modules, encoder & IR receiver module
2) Both boards use the same Apple remote
3) Both boards can use the same power supply
4) The V25 is slightly wider and longer than the V2 so the mounting holes will be different.
5) The V25 has its own input switching so you'll no longer need your existing external switching board used with the V2
6) Both boards use the same 5 pin USB header connection except the header is on the underside of the V25 board
7) The V25 board has no piggy-back board on its underside so overall the V25 can be mounted lower than the V2.
8 ) With the V25 you MUST connect the IR receiver module to the master display module since there's no place to mount the IR receiver directly to the V25 board itself.

enser

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Re: LDR.V25 (the "V25") Preamp Controller
« Reply #61 on: 10 May 2017, 10:11 pm »
Morten,

Will there be the option on the V25 to supply your own regulated +5v (I have a Belleson reg based PSU I'd like to use).

tortugaranger

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Re: LDR.V25 (the "V25") Preamp Controller
« Reply #62 on: 11 May 2017, 01:28 pm »
Morten,

Will there be the option on the V25 to supply your own regulated +5v (I have a Belleson reg based PSU I'd like to use).

There's no deliberate option to bring in an external source of 5 V. That said, you could achieve this by removing the U11 5V regulator entirely and connecting a +5V and Gnd at the solder pads. The existing regulator uses the 7805 pin out although it's not a 7805.

Before going down that road it's worth reviewing the power supply arrangement and asking yourself if this is really worth it.

First, the existing U11 5V regulator is a high performance low noise switching regulator that's essentially a 7805 drop-in replacement. Second, the 5V supply is not directly used to power the primary LDRs although it is used to power the on/off LDRs used for input switching. Lastly, the 5V is further regulated down to 3.3V via a low noise low dropout linear regulator. The 3.3V  power is used to power the processor and to regulate the LDRs used for volume control.

In my view, the V25 is unlikely to benefit from being powered directly from an external 5 V source. I can't prove that. It's simply an engineering judgement. I've been wrong before about the impact of power supply quality on the V2 board design but the V25 is quite different from the V2. With the V2 the incoming power source is used directly (no filtering/conditioning etc.) to power the 2 op amp chips that are part of the LDR control circuit. With the V25 there's 2 stages of voltage regulation (SMPS followed by linear) upstream of the control op amps.

tortugaranger

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Re: LDR.V25 (the "V25") Preamp Controller
« Reply #63 on: 11 May 2017, 02:16 pm »
One aspect of the V25 design that I've probably not mentioned before is that unlike the V2 design which maintains minimal power on some LDRs even when "turned off",  in the V25 all the LDRs are 100% powered down when the unit is turned off. Hard to quantify the long terms benefits other than to say it will arguably extend the useful life of the LDRs just that much longer.  :thumb:

enser

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Re: LDR.V25 (the "V25") Preamp Controller
« Reply #64 on: 11 May 2017, 05:46 pm »
Agreed, too complex and not worth it. Generally (well 99.99% of the time) I'd rather go with the engineered solution by the designer, just wanted to see if there was a straightforward option with +5v that met the prior statement.
Thanks!

mlundy57

Re: LDR.V25 (the "V25") Preamp Controller
« Reply #65 on: 11 May 2017, 07:09 pm »
Will the V3 have an HT by-pass feature?

I use my main speakers for both music and HT. For music I have three inputs the DAC connected to my music server for digital files, the 2 channel output from an OPPO 105 for SACD & DVD-A, and my turntable. The AVR handles movies.

Without an HT by-pass I have to use two different sets of speaker cables and a pair of dummy loads with the main speakers and switch back and forth for music or movies.

With an HT by-pass (that feeds both outputs since my speakers are bi-amped) the AVR's main pre-outs would be connected to the HT by-pass input which would eliminate the need for the second pair of speaker cables, the dummy loads and the need to switch back and forth.

Mike

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Re: LDR.V25 (the "V25") Preamp Controller
« Reply #66 on: 12 May 2017, 01:01 pm »
Will the V3 have an HT by-pass feature?

I use my main speakers for both music and HT. For music I have three inputs the DAC connected to my music server for digital files, the 2 channel output from an OPPO 105 for SACD & DVD-A, and my turntable. The AVR handles movies.

Without an HT by-pass I have to use two different sets of speaker cables and a pair of dummy loads with the main speakers and switch back and forth for music or movies.

With an HT by-pass (that feeds both outputs since my speakers are bi-amped) the AVR's main pre-outs would be connected to the HT by-pass input which would eliminate the need for the second pair of speaker cables, the dummy loads and the need to switch back and forth.

Mike


Before I answer your specific question, I want to clarify that our recently released V25 has effectively displaced the V3 which is no longer being developed.


The V25 doesn't have a specific HT bypass feature. That said, there's a very straightforward way to use the V25 in a bypass mode. Attach your HT to one of the V25 inputs and when that input is selected raise the V25 volume to 100%. At that point use your HT to control volume. While not a true physical bypass it accomplishes the same outcome. No worries when you switch the V25 back to some other input because it automatically cuts the volume level back to a default max level of 50%.


mlundy57

Re: LDR.V25 (the "V25") Preamp Controller
« Reply #67 on: 12 May 2017, 04:18 pm »

Before I answer your specific question, I want to clarify that our recently released V25 has effectively displaced the V3 which is no longer being developed.


The V25 doesn't have a specific HT bypass feature. That said, there's a very straightforward way to use the V25 in a bypass mode. Attach your HT to one of the V25 inputs and when that input is selected raise the V25 volume to 100%. At that point use your HT to control volume. While not a true physical bypass it accomplishes the same outcome. No worries when you switch the V25 back to some other input because it automatically cuts the volume level back to a default max level of 50%.

For that to work in my system without having to go back to swapping out two pairs of speaker cables when I switch from listening to music to watching movies, the V25 would have to have four inputs instead of three: (1) OPPO 105's 2 channel analog outputs, (2) the file server's DAC, (3) the phono pre-amp, and (4) the AVR for movies and multi-channel music.

While I used to do this since my preamp only had three inputs, now that I have a pre with the HT by-pass/4th input and no longer have to swap out speaker cables I've become spoiled and don't want to go back.

Maybe something to keep in mind for a future upgrade.

Thanks

Mike

tortugaranger

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Re: LDR.V25 (the "V25") Preamp Controller
« Reply #68 on: 12 May 2017, 04:42 pm »
For that to work in my system without having to go back to swapping out two pairs of speaker cables when I switch from listening to music to watching movies, the V25 would have to have four inputs instead of three: (1) OPPO 105's 2 channel analog outputs, (2) the file server's DAC, (3) the phono pre-amp, and (4) the AVR for movies and multi-channel music.

While I used to do this since my preamp only had three inputs, now that I have a pre with the HT by-pass/4th input and no longer have to swap out speaker cables I've become spoiled and don't want to go back.

Maybe something to keep in mind for a future upgrade.

Thanks

Mike

Hi Mike,

Sorry the misunderstanding but the V25 can accommodate up to 6 stereo inputs directly on the board - no additional external input switching hardware required. Any one of those 6 could be your AVR input. If you only need 4 inputs no problem. When the 4th input (your AVR) is selected just run the volume up to 100% - instant HT bypass (effectively).

Best,
Morten

mlundy57

Re: LDR.V25 (the "V25") Preamp Controller
« Reply #69 on: 12 May 2017, 04:55 pm »
Hi Mike,

Sorry the misunderstanding but the V25 can accommodate up to 6 stereo inputs directly on the board - no additional external input switching hardware required. Any one of those 6 could be your AVR input. If you only need 4 inputs no problem. When the 4th input (your AVR) is selected just run the volume up to 100% - instant HT bypass (effectively).

Best,
Morten

You have my attention.

What's the status of the V25?

Mike

tortugaranger

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Re: LDR.V25 (the "V25") Preamp Controller
« Reply #70 on: 12 May 2017, 05:57 pm »
You have my attention.

What's the status of the V25?

Mike

The V25 has been released but we are roughly 2-3 weeks behind in shipments. Putting a huge effort into optimizing the auto-calibration algorithm which has slowed shipments to a crawl. Expect to break the logjam any day now. The V25 has a way more sophisticated control scheme compared to the V2 so adapting the V2's algorithm to the V25 has taken much longer than planned.

mlundy57

Re: LDR.V25 (the "V25") Preamp Controller
« Reply #71 on: 12 May 2017, 06:01 pm »
Thanks

I just finished reading the V25 thread so I'll be following that one

Mike

tortugaranger

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Re: LDR.V25 (the "V25") Preamp Controller
« Reply #72 on: 12 May 2017, 06:15 pm »
Thanks

I just finished reading the V25 thread so I'll be following that one

Mike

I've merged both topics into the V25 thread since they were so closely related.

WC

Re: LDR.V25 (the "V25") Preamp Controller
« Reply #73 on: 31 May 2017, 07:50 pm »
So can a pair of boards running as a balanced pair be combined with boards running single ended in a multi-channel application?

The first two boards will run the front right and left speakers balanced. My center and surrounds will be single ended or unbalanced. So that would be another two boards running single ended. Is this possible with the board controller?

tortugaranger

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Re: LDR.V25 (the "V25") Preamp Controller
« Reply #74 on: 31 May 2017, 08:14 pm »
So can a pair of boards running as a balanced pair be combined with boards running single ended in a multi-channel application?

The first two boards will run the front right and left speakers balanced. My center and surrounds will be single ended or unbalanced. So that would be another two boards running single ended. Is this possible with the board controller?

Multiple V25 boards can be daisy-chained together with one ultimate master board. The first slave connected to the master passes on all commands to the next slave and so on. Communications between each board is currently one-way (master->slave1->slave2 etc. ) via serial UART protocol. Eventually we will add 2 way comm so slaves can send data upstream to the master.

Each V25 can handle 2 channels. Hence for stereo balanced you need 2 boards for 4 total channels (2 right channels & 2 left channels). Add up all the channels you want to control and divide by 2 and round up to get the number of V25 boards needed. For 5 channels 5/2 = 2.5 or 3 V25 boards.

Also, something I haven't broadcast is that any computer, arduino, raspberry PI etc. equipped with a UART (very common serial comm) could act as a master to control 1 or more V25 boards.

WC

Re: LDR.V25 (the "V25") Preamp Controller
« Reply #75 on: 1 Jun 2017, 08:58 pm »
So how would another controller connect to the board? Terminal pins or USB? Learning about serial communications with my Soekris DAC build. Interesting thing to tinker with.

tortugaranger

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Re: LDR.V25 (the "V25") Preamp Controller
« Reply #76 on: 2 Jun 2017, 02:05 pm »
So how would another controller connect to the board? Terminal pins or USB? Learning about serial communications with my Soekris DAC build. Interesting thing to tinker with.

Via a connection to pin RX2 on header J7 -  a single wire serial data link. Using standard UART protocol at 115,000 baud, 8 bits, 1 stop bit, no parity. We haven't published the commands yet but will do so in the future and post this info in our online documentation.

Currently this is only one-way  external controller -> V25.J7.RX2.   Future V25 firmware will enable 2-way communication by adding a second serial wire connection via V25.J7.TX2 - > external controller.

 For those unfamiliar with UART (or USART) it's an old yet reliable serial data protocol going way back to analog telephone days and is closely related to RS232 et. al.  All Arduinos, microcontrollers, Raspberry PI's etc. have this built into their hardware. PCs used to all have RS232 before moving to USB which is way more complex  but faster and more flexible but there are cheap USB/UART interface adapter devices available for PCs and MACs.

WC

Re: LDR.V25 (the "V25") Preamp Controller
« Reply #77 on: 2 Jun 2017, 04:43 pm »
So would your display either the 7 segment or the new OLED display still be required if we could use UART control?

I was thinking if I could install the LDR.V25 in my DAC/Raspberry Pi streamer and use one display that shows DAC and LDR settings such as inputs and volume control. Would have to interface with a UART controller on the pi, or an arduino due if the pi can't address multiple UART satisfactorily. I am assuming that the LDR.V25 and DAC will need different UART controllers since the command sets are different.

tortugaranger

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Re: LDR.V25 (the "V25") Preamp Controller
« Reply #78 on: 2 Jun 2017, 04:56 pm »
So would your display either the 7 segment or the new OLED display still be required if we could use UART control?

That would be up to you. The V25 would display normally to whatever display is attached. Or, you could handle all of that with your own display being driven by your arduino, PI etc.

Quote
I was thinking if I could install the LDR.V25 in my DAC/Raspberry Pi streamer and use one display that shows DAC and LDR settings such as inputs and volume control. Would have to interface with a UART controller on the pi, or an arduino due if the pi can't address multiple UART satisfactorily. I am assuming that the LDR.V25 and DAC will need different UART controllers since the command sets are different.

Generally speaking UART is not good for networking of multiple devices off a single UART pair. You would likely need a dedicated UART port for each device you're communicating with. In the case of the V25, daisy-chaining 2 or more boards together is done by using 2 separate UART ports per board instead of all the boards being on a single UART link.

MadKid

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Re: LDR.V25 (the "V25") Preamp Controller
« Reply #79 on: 13 Jun 2017, 08:17 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.