DEQ2496 consumer level analog board

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Pulse-R said:


Perhaps not the correct link for analog board ?

looking much better, but lots of parts

Yes, look better with the right link DEQ miniAnalog beta6.

26 parts + 2 to 4 connectors. Not so bad. ;)

I made some testing inside my DEQ yesterday night. The pcb will be around 30x100 or less, flat on the dsp board. No way to have it placed at the vertical.
 
janneman said:
Delete C7,8,13,14. They were part of the cap load isolation. So, now you're down to 22 parts ...;)

Jan Didden

You understand why I was looking for the THAT chips at start. The resistors are inside. ;) but the 1632's specs are far better.

At Farnell, the OPA1632D cost 2.88€ and THS4131D 5.55€ !!!

Seems to be as the OPA2134 and OPA2132 story...

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First draft.

Very difficult to route with only 2 sides...:D

miniANALOG-proto1_real.jpg
 
AndrewT said:
split r11 and insert a passive filter.

I have never seen an MFB with balanced inputs before.
Do both inputs have the same filter characteristic?

Yes,

The output circuit is adapted from the circuit found in my Tag AV32R (very nice sound). I'm not sure that R7/C9 is really needed. In the original circuit, you have an CS3310 between IC1 and R7.

r11 replaced with a RC filter? Why?

Stef...
 
r7 & c9 are part of the second MFB filter.
r7 sets the gain in conjunction with R10, c9 complements c10 setting the Q.

The output from the servo must not contain any audio.
A filter on the servo output attenuates any remaining audio and noise and distortion that the opamp tries to inject back into the non-inverting input pin.
If r11=100k, then r11a=r11b=51k and c=3u3 or so, for 1Hz filter
 
Thanks Andrew for the details on the servo parts.

To complete on the Tag output circuit, the value are these. Next to the first MFB filter circuit, you have the CS3310. As you, I never saw a circuit as this. It don't come from the orginal schematics but from y own reverse. After, the CS, you have the output buffer and servo as described previously.

The 330pF are FKP2 from Wima. Others are MKS2.

An externally hosted image should be here but it was not working when we last tested it.
 
janneman said:

Too many opamps ;)
Why do you need a buffer & servo?

Hi Jan!

The best part's killer man. ;)

That's easy, I don't know how to do the bessel filter and remove the coupling caps with less.

I've found various circuits with only one opamp but with chimical at DAC output. Don't like. I had also a look on the nelson pass web site, but so many discret components. Will take a lot of space. Look fun with the coils.

http://www.aoselectronics.com/gfx/ally/ppa_db_v1.1.gif

All this stufff need to fit in a 30x96mm pcb...

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