An idea of the result. The two board will fit if you not use too high caps. The output board is the one without Cx caps.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
AndrewT said:
Andrew, I don't think his circuit inverts the phase. He has +DAC to +in and -DAC to -in.
Jan Didden
Small is beautiful.
No no, I'll not use a LM4562...
(the board have ground plane on botton side)
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No no, I'll not use a LM4562...
An externally hosted image should be here but it was not working when we last tested it.
(the board have ground plane on botton side)
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Two interesting file found in the forum (from sidiy).
Bessel part 1
bessel Part 2
Where is stored my HP41C.
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Bessel part 1
bessel Part 2
Where is stored my HP41C.
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Hi,
but the MFB is an inverting filter.
Two of these stages cascaded (as in the Tag) will result in correct phase.
But remove one and the output phase will be inverted.
Solution is easy, just swap the inputs.
but the MFB is an inverting filter.
Two of these stages cascaded (as in the Tag) will result in correct phase.
But remove one and the output phase will be inverted.
Solution is easy, just swap the inputs.
AndrewT said:
Lost. 😀
On the Tag, the OUT+ is connected on the negative input of the first opamp, follow, the CS3310, and the second op-amp still connected on the negative input.
If I follow you. The 2 MFB correct the phase but why OUT+ connected to the inverting input?
An externally hosted image should be here but it was not working when we last tested it.
And in my circuit, I've this:
An externally hosted image should be here but it was not working when we last tested it.
Right! Wrong!
In TI FilterPro, we have a red sentence at bottom screen marked "Note: Phase response is not connected 180° for inverting stages.".
Completely lost!
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An externally hosted image should be here but it was not working when we last tested it.
Hi!
Nobody to answer for the correct DAC output way?
I worked a little more on the filter. I changed C3/C6 for 680pF and got a better curve.
The TINA-TI file if you want to play.
Nobody to answer for the correct DAC output way?
I worked a little more on the filter. I changed C3/C6 for 680pF and got a better curve.
The TINA-TI file if you want to play.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Last shematics:
- Inverted 15v input on INPUT and OUTPUT board. Better for PCB trace.
- INPUT: removed Cx
- INPUT: added R19 and R20
- INPUT: changed value for C3 and C7
miniANALOG beta10
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- Inverted 15v input on INPUT and OUTPUT board. Better for PCB trace.
- INPUT: removed Cx
- INPUT: added R19 and R20
- INPUT: changed value for C3 and C7
miniANALOG beta10
.
AndrewT said:
Its only inverting if you put the 'right' phase into the -input. Here, it is definitely not the case: DAC+ into +in, DAC- into -in. No phase inversion.
Jan Didden
stef1777 said:
That sentence refers to the graph: the graph has absolute phase shifts through the filter. Because that filter does 180deg shift, the phase shift from Vin to Vout = 180+the curve.
Jan Didden
janneman said:
Thanks you for the explanation.
I plan to send the files to the factory Monday. I'll have 3 input boards and 2 output boards. If you have some recommandation, this is the last turn. 😉
Found this following circuit in the AD1852 datasheet.
An externally hosted image should be here but it was not working when we last tested it.
I's raining on Paris today.
You won a new beta schematics.
Changes: again moved signals on J2/J4 connectors.
😉
You won a new beta schematics.
Changes: again moved signals on J2/J4 connectors.
😉
Why is that Vcom so strange? It should be grounded since it sets the common mode OUTPUT, and not the input. The common mode input will be attenuated in the OPA1632 itself already by 95 dB 🙂 And where is the filter?
4real said:
The filter is on the DSP board. See the small box at botton right on the INPUT schematic.
Sorry but not understood your question about Vcom. It's Vcom or Vocm, you're taking about?
Stef...
The stuff is in two parts? Or have I missed something?
If so: why not do everything at ones? Filtering and output with a single OPA1632?
With Vcom, I mean the common mode input of the OPA1632 (betweeen + and -). Looks like you are setting it to 2.5V. Why?
If so: why not do everything at ones? Filtering and output with a single OPA1632?
With Vcom, I mean the common mode input of the OPA1632 (betweeen + and -). Looks like you are setting it to 2.5V. Why?
4real said:
The filter is already in the DSP board. Behringer placed it right to the ADC chip. I use it to simplify.
On the AK5393, Vcom is 2.75v max. It's not possible to connect VcomL and VcomR from the AK to the OPA1632 without a large surgery.
Look at one of the Jan's post previously in this topic.
Stef...
stef1777 said:
Ah, I did not know that, thought it were on the output board? I that also the case with the DCX (doesn't look like it)?
Yes, I know, but in the filter you already have, there is no common mode voltage (see second page of your last design)!
Edit: I think I'm getting stuff confused here... Sorry for that!
You use the OPA1632 for the input and the rest as ouput. That's where I was confused
So nevermind 
Actually, in my DCX, I do want to do the surgery 😉
4real said:
You use the OPA1632 for the input and the rest as ouput. That's where I was confused
No problem.
You have 2 boards. One input and one (optional) output board. Myself, I will not use the output board. I prefer to stay with the XLR output. I've UcD amp. Separating the 2 boards is also fine if someone want to use my small input board and build another highend output board, or connect it to a volume control circuit. If not used, you need to strap out+/-/L/R on the input board.
What do you think of the bessel filter proposed values?
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Well, I'm not that much into filters. I'm going to wrestle with it in a few weeks myself. I guess if your simulated groupdelay is good, you should be fine 🙂
