Old School! Ultracurve8024 DAC upgrade, trans output, USB-midi remote control!

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Old School! The date code on the back of mine is 10 01 ... that's probably older than the youngest members at diyaudio 😱

(This assumes you have the digital in/out board since ... this is about making a DAC)

Gotta start with T's groundbreaking article on 8024 upgrading, use and room nodes:

Behringer Ultracurve Pro 8024 Digital Equaliser by Thorsten Loesch

Classic! 😎

Here's the spec sheet and you can get the manual from the pull-down menu at the product website:
Behringer: ULTRA-CURVE PRO DSP8024

View attachment DSP8024_P0022_S_EN.pdf


PCB
ultracurve 8024 pcb.jpg


CS8412 Rx
cs8412 Rx.jpg

PS upgrade
cs8412 rx ps upgrade.jpg


CS4390 DAC
cs4390.jpg

PS upgrade
cs4390 dac  ps upgrade.jpg

Get at the DAC balanced outputs with a plain pin header
dac out pinheader.jpg


Tried transformer output: bal to bal and bal to single-ended conversion, 100kHz [1527] filtering, and electrical isolation, 2V output ... what's not to love?

With cheap Edcor wsm10k-10k
trans output edcor wsm10k-10k.jpg


And Lundahl LL1527XL (w Andrea's circuit: DAC 1.0)

batt powered cs4390 trans output lundahl LL1527XL.jpg

Which is also a 12V SLA batt powered DAC!

Neat, with no I2S it draws 4 mA, with I2S 43.8mA (pause, quiet) and 44.2 (rockin' 😀)

Now here's the cool part ...

At the product site under the downloads tab is ... Remote midi software:
Behringer: ULTRA-CURVE PRO DSP8024
(and firmware v1.3)


The 8024 push-button interface was always a bit clunky but this remote control sw might be much more user friendly ... and with a laptop you don't have to get out of your chair!

And here's a cheap USB-midi cable (ebay)!
usb midi cable.jpg



😉
 
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Here's the CS8412 Rx spec
View attachment cs8412.pdf

and the CS4390 DAC spec is here

http://www.sm0vpo.com/_pdf/special_function/CS4390.pdf

Another transformer option is shown in the Jensen JT-11SSP app note:
View attachment CS4396 trans out as093.pdf


Or you could go passive balanced like in Jan's article:
Home

View attachment dcx passive article.pdf

😎



Why the Ultracurve you ask? Well, ... why the hell not!?! It was just sitting all lonely on the dusty shelf :guilty:

And ... it sounds pretty good with the mods -- especially trans out--highs sound very nice and I love cymbals :hug:



The CS8412 is still pretty good and the better bypassing (and maybe later an individual ps) helps. The CS4390 is ok (onchip med quality opamps) but the better bypassing helped there too and battery power is interesting.



And the CS4390 is 24bit, I wonder if just upgrading the CS8412 to a 8414 would work ... ???

Any ideas for further upgrades?

Cheers,
Jeff
 
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Here's the 8024 CS4390 circuit:

CS4390 circuit.JPG

I was able to get 805 sm caps on the pins of the bigger CS8412 Rx but man those DAC pins are 'toight' (Austin Powers). Would fit sm 605 fit?

They have ceramic bypasses already but they're further than the electros?!? 😡 An easier fix than trying to 605 the pins would be 805 on the pins of the electros but they're still pretty far away from the chip. Hmmm, might have to practice my sm soldering and go for the pins ...

I also wanted to provide separate regulation to the Vd and Va of both the 8214 Rx and 4390 DAC but it looks like the supplies are joined under the chip. 😡

CS4390 specsheet circuit.JPG

Oh wait, I think R91(2.2ohm) is the res that connects the supplies ... I'll buzz it out.

Any idea what R88(470ohm) and R90(100ohm) are for?

Any other suggestions?

Cheers,
Jeff
 
Here's a better pic of the 2x5 pinheader for those who want to give it a try!

4390 DAC, reg, pinheader out.jpg

A little bend out on the two ends of the far row, a little bend in on the next ones towards the center pin, center pin bent back to back row, back row bent up and all go to gnd.

Where would be the ideal place to gnd? How about the doable?

🙂
 
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😡
You'd think that the ps caps at the top of the chip would go to the ps pins near the top. And you'd think that the ps caps at the bottom of the chip would go to the ps pins near the bottom. But nnnnnnoooooooo!
😡

😱 So here's where the pin header gnd should go, near the Va ps.

pinheader proper Agnd, indiv DAC Va Vd regs.jpg

And the 2.2 ohm R91 was the ps bridge res, so I removed it and added another reg to Vd (Va ps is the side of the original reg).

So now Va and Vd both have their own reg, OSCON and 100n Y5V under the CONs. The supplies seem to be starting and rising close enough to not cause trouble (so I don't have to force them to stay close by putting dual diodes where R91 was)

Oh about R88(470ohm) and R90(100ohm). The top of R90(100ohm) goes under the chip and to ... LRCLK ?!?:xeye:

Here's the bottoms ...

ultracurve 8024 pcb bottom.jpg

Rx Tx PCB CS8412 pcb bottom.jpg
 
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