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3 x δ1 boards system

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3 x δ1 boards system

Postby whomper » March 2nd, 2018, 12:24 am

Hi,

My setup include a digital source that feeds a DCX2496 which in turn feed an analog 4 channels to a alpha24 pre-amp (LCDuino-1, 2 x δ1 based on alpha24) and then a pair of Beta24.
As I plan to add a powered sub, I need to increase the pre-amp channel count by one which will require a third δ1 board.

Is that setup supported? In documentation it states that up to two of each boar type is supported, which means this might require a firmware upgrade if possible hardware wise.
κDC2496, γ1.5, γ2, γ3, α10 (α24 based), balanced β22, 2 x β24, M³, Grado ES2E, GS2000E, AGK K700, CBT36 Speakers
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3 x δ1 boards system

Postby amb » March 2nd, 2018, 2:52 am

The LCDuino-1 firmware allows two board configurations:

"unbalanced": one δ1 (and one optional δ2)
"balanced": two δ1s (and two optional δ2s)

If you want 3 channels, you could set up the LCDuino-1 for "balanced" and install two δ1s. On the second δ1, populate only one channel for the subwoofer. No firmware modifications should be necessary.
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Re: 3 x δ1 boards system

Postby whomper » March 2nd, 2018, 5:32 am

Since I have an active setup, I'm using one δ1 per channel (either left or right) which already takes up two δ1. I need to configure a third δ1 for the sub channel, essentially making it a 5 channel setup.
κDC2496, γ1.5, γ2, γ3, α10 (α24 based), balanced β22, 2 x β24, M³, Grado ES2E, GS2000E, AGK K700, CBT36 Speakers
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3 x δ1 boards system

Postby amb » March 2nd, 2018, 5:46 am

Oh, I forgot you have a balanced system. Currently the LCDuino-1 firmware only supports up to two δ1 and two δ2 boards. Without modifying the firmware, maybe you could run a third δ1 configured to the same I2C address as one of the other δ1s, so they would work "in parallel". You would have to test it to see if this is a reliable solution.
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Re: 3 x δ1 boards system

Postby whomper » March 24th, 2018, 3:01 am

Before ordering and building another δ1 board, I've moved the two already available δ1 boards on the same address and tested the system. So far, volume changes as expected on both boards sharing the same address.
I'll be looking to build a third board to support a completely active systems with sub woofers: with 2 active speakers and 1 sub woofer (one 12" in place, might add another one in the future).

I guess I do not need to increase power transformers as the 2 extra alpha24 and 2 extra δ1 boards should not impose too much load on the current transformers.

Out of curiosity, what's the theoretical limit on number of boards on same address? Best practice is 1 per address, but perhaps one can add a few more without any issue?
κDC2496, γ1.5, γ2, γ3, α10 (α24 based), balanced β22, 2 x β24, M³, Grado ES2E, GS2000E, AGK K700, CBT36 Speakers
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Re: 3 x δ1 boards system

Postby whomper » October 19th, 2018, 9:41 am

Hi,

A quick update. I've completed this build a while ago and am posting updated images. Have moved all three boards to the same address and it works! Power transformer also holds up nicely with the 6 alpha24 boards.
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κDC2496, γ1.5, γ2, γ3, α10 (α24 based), balanced β22, 2 x β24, M³, Grado ES2E, GS2000E, AGK K700, CBT36 Speakers

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Re: 3 x δ1 boards system

Postby amb » October 19th, 2018, 11:43 am

Beautiful build, as usual!
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Re: 3 x δ1 boards system

Postby DEFL » October 19th, 2018, 11:44 pm

Beautiful build!
Your finding opens whole new perspective of using δ1 and δ2.
After your post in March I personally consider trying to use 2 x δ2 located at the rear of amplifier for inputs, and 2 x δ2 located at the front for outputs.
Question to you and maybe to Ti: have you tried skipping digital part of δ1 on 2 boards out of 3?
Since they are sharing the same address, maybe only one digital part needs to be populated, other boards wired thru J5 connector.
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Re: 3 x δ1 boards system

Postby amb » October 20th, 2018, 12:29 pm

Using only one digital portion to drive two relay boards means that each transistor in the ULN2003 darlington array will “see” two paralleled relay coils. The resultant switching current will be doubled and the 47Ω resistor arrays will drop too much voltage. To keep the currents low I don’t recommend connecting it that way.

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