| What is the simplest way, to convert this GC to a subamp? - Click HERE for Original Thread |
| Franz G |
I am looking for the simplest idea, to convert this NIGC to a subamp:
- what is the easiest method to filter (lpf 100Hz), eg. use a buffer or not?
- what is the easiest method to mix both stereochannels?
Thanks for all ideas!
Franz |
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| miguel2 |
In the Pass Labs diy site you find the articlle of el pipe-o with a filter to be connected to output of the main speakers amp.
Miguel |
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| jackinnj |
try this:
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| Franz G |
Do I interpret this correctly?
This circuit is showing a crossover, mixing two channels and using two opamps (like OPA627).
So, I could bridge or paralleling the two output chips in this case.
Franz |
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| carlosfm |
That's right.
You sum the two channerls, then filter after that.
That way, you use half the parts because you don't need to apply filtering per channel.
On an already-made amp it's more practical to parallel.
EDIT:
Oh.:eek:
The summing op-amp has to be inverted.:bawling: |
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| Franz G |
| quote: | Oh.
The summing op-amp has to be inverted. |
Could you explain this? I dont understand.
Franz |
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| jackinnj |
maybe we can dispense with the buffer, etc. in their entirety -- although I would hold my breath -- i haven't wired this up:
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| Franz G |
3.83M for the feedback resistor?
No, remember the t-net! Too high resitance for a good feedback, nearby 4M!
I think, it is better to use dedicated opamps for filtering, when I look at this circuit!
Many thanks, jackinnj! I will try the first circuit, you showed in this thread.
Franz |
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| carlosfm |
| quote: | Originally posted by carlosfm
The summing op-amp has to be inverted.:bawling: |
| quote: | Originally posted by Franz G
Could you explain this? I dont understand.
Franz |
Sorry, my confusion.
It can be inverting or non-inverting.
But with some requirements, if you don't want to have high DC-Offset.
Here is my sketch from when I made my sub.
I used an OPA2132 as input buffer and then an OPA4228.
Power amp is 2 // OPA549s. |
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| Tube_Dude |
| quote: | Originally posted by carlosfm
Sorry, my confusion.
It can be inverting or non-inverting. |
Hi Carlos
You were right!! A inverting stage is better for summing two channels, because the summing point is a "virtual ground" and don't permit signal leakage from one channel to the other...
À nossa!!:drink: |
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| carlosfm |
| quote: | Originally posted by Tube_Dude
Hi Carlos
You were right!! A inverting stage is better for summing two channels, because the summing point is a "virtual ground" and don't permit signal leakage from one channel to the other...
À nossa!!:drink: |
Hi Jorge!:cool:
Yes, I'm a little confused today, hard day at work.:xeye:
I've just connected the soldering iron, I will get better soon.:D
I actually used inverting summer on my sub, with an input NI buffer (it's not on my sketch).
À nossa. :drink: |
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