Passive Line Filters? (BD-Design)
Ok, you're right: the simpler the better.
Is it that simple?
[img]images/uploaded/image237.jpg[/img]
After all I need a reference before tweaking the amp output filter.... 
Passive Line Filters?
by Bert 
, Saturday, March 17, 2007, 20:49 (6260 days ago) @ Giovanni
Nice picture!
Yes, it is that simple. Just add another stage behind that with the next resistor 10x the first value and the capacitor 1/10th and you have 12dB.
Looking at the values, better ad a stage in front with 1/10th te resistor value and 10x the capacitor value....
And, the pre is the loudspeaker connection for the mid- and high frequencies!
Ciao,
Bert
--
BD-Design - Only the Best!
Passive Line Filters?
"Visual" schematics
Do I need an RC high pass filter too?
[img]images/uploaded/image239.jpg[/img]
More like this...
by Bert , Sunday, March 18, 2007, 00:29 (6260 days ago) @ Giovanni
[img]images/uploaded/image240.jpg[/img]
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BD-Design - Only the Best!
Like this?
[img]images/uploaded/image241.jpg[/img]
No, you are mixing signals...
by Bert , Sunday, March 18, 2007, 09:43 (6259 days ago) @ Giovanni
Compare both pictures
[img]images/uploaded/image241.jpg[/img]
[img]images/uploaded/image242.jpg[/img]
The lower one (note the changed values) is were the filter is using the signal similar as going to the Fostex drivers (high gain). This is usually needed because the used filter principle is reducing gain a lot and AMP2 for the FW208N is "boosting" the lost in gain. With an attenuator you should adjust the gain for that amp.
You could also use a separate output of your pre-amplifier but then the filter should not be connected to the output of AMP1 at the same time as in your picture. The pre-amplifier should have its own dedicated buffer to "drive" that filter for the bass and you should be able to adjust the gain going to AMP1 seperately (reducing gain)
If both outputs of the pre-amplifier are simply connected in parallel then the filter is doing its things on both the main amps (crossing at 200Hz).
Ciao,
Bert
--
BD-Design - Only the Best!
Some additional thoughts...
by Bert , Sunday, March 18, 2007, 10:16 (6259 days ago) @ Bert
I am not sure how your bass amplifier works though but if this amp is connecting both the grounds of the filter then this is also connecting both grounds of AMP1. If this is a T-amp then it might not work....
Here I always use 2 separate amplifiers for the bass (2 mono amps with own power supply) and that does not give problems...
Ciao,
Bert
--
BD-Design - Only the Best!
Some additional thoughts...
Thanks for the patience.
Another trial:
![[image]](images/uploaded/image243.jpg)
Wolfson DAC outputs 2V rms and I can easily double T-Amp input gain.
Some additional thoughts...
by Bert , Sunday, March 18, 2007, 13:43 (6259 days ago) @ Giovanni
Yep, that would work... :wink:
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BD-Design - Only the Best!
Some additional thoughts...
by PeterSt. 
, Netherlands, Sunday, March 18, 2007, 13:57 (6259 days ago) @ Bert
Will it ?
Only if the general volume is controlled in the digital domain I think ...
Peter
Some additional thoughts...
by Bert , Sunday, March 18, 2007, 14:20 (6259 days ago) @ PeterSt.
Only if the general volume is controlled in the digital domain I think...
I think that this is what Giovanni wants to do (he talked about digital filters later on if he could manage the timing or something like that...)
Not optimal, we know, but everybody is free to do what they want.
Unless he wants to use the pre-amp as volume control, then it won't work of course... 
Ciao,
Bert
--
BD-Design - Only the Best!
Some additional thoughts...
One volume control will be in the BosoZ Pre (not shown) and another 10K pot in the T-Amp.
Some additional thoughts...
by Bert , Sunday, March 18, 2007, 15:51 (6259 days ago) @ Giovanni
One volume control will be in the BosoZ Pre (not shown) and another 10K pot
in the T-Amp.
Does this mean that you have to turn two controls to attenuate the bass and the mid-high seperately? Then it will work but it won't be very comfortable...
You do not have that problem if you take the signal from the mid-gigh drivers... :wink:
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BD-Design - Only the Best!
Digital alternative for Filters?
This would be the digital alternative:
[img]images/uploaded/image246.jpg[/img]
Emu1212M can control two independent digital outputs (the one is its internal DAC board) and apply independent filtering for each one.
Disadvantages?
Digital alternative for Filters?
by Bert , Sunday, March 18, 2007, 16:18 (6259 days ago) @ Giovanni
Disadvantages?
Ehhhh, jitter? Not "bit-perfect"?
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BD-Design - Only the Best!