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Active filter board GB

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#321
You'll see a roll off in the individual section's response. The sum of the bandpass (mid) response and high pass (tweet) can be made flat.

All filters have a rounded corner - even 100+ dB/octave digital filters. Where the droop begins is determined by the sections order and Q.

I'm not sure what you are asking about attenuation. If you know the desired attenuation, you can replace the pot with a fixed resistor calculated to give the appropriate attenuation with the chosen resistor to ground. I'm on my way to a meeting so I cannot calculate it at the moment. attenuation = 20 log(V1/V2) so work a voltage divider to make your desired attenuation.

Or, if you want to use a tapped autoformer, just take the output from the jumpers that select 2nd or 4th order and feed that to your autoformer, leaving the output buffers unstuffed.
 
#324
I know I'm late to the party, but if you actually have some spares looking for an owner...

my needs would be to build a stereo setup for

18 dB/octave @ 200 Hz (low Pass)
12 dB/octave @ 200 Hz (high pass)

or somewhere around 250hz,

ideally with the ability to add a subwoofer below 60 hz one day.,

From what I rad in the thread that would be 4 boards, maybe some spares in case I goof.

I'd be happy to take some of your spares or no-pays - let me know. Got a Bryston 10b sub for sale if I get this working 🙂

peter
 
#328
Hey Bob, do you want delivery confirmation on the WIKI for RII? I noticed it wasn't set up yet, but I didn't want to leave you hanging if you were looking for replies. BTW, the boards look VERY nice. I can't wait to fire them up.

David
 
#330
Got my package today in good shape. I am going to build a stereo 3-way in the chassis of my existing Pyle $60 "pro" crossover. That way I have a head start with connectors and level controls. Maybe a notch filter to tame down the NEO3PDR tweeters too...Then maybe the Ultra-low sub....

Bob G.
 
#331
There have been a couple of packing errors noted. Please email me directly if you have the wrong stuff in your package. I'll make it right.

I suspect some will find filter boards instead of PSU boards. I don't have as many filters and more PSUs than I thought I would. There are enough filter boards to cover those ordered, but I only have a few for myself. I'd sure appreciate getting them back.
 
#337
Odd order filters were not covered in the manual. There are a few things I'd like to add. I guess I need another trip with long airport layovers to update it.

Here is a way to make an odd order filter on the AF4 board.

Oddorder.jpg


In case the notation is not obvious, the part numbers missing the component symbol are omitted, and the red lines indicate jumpers. Low pass is similar.
 
#338
received the boards

Hi Bob and Jens,

Received the boards OPA's and PSU stuff a couple of days ago but wasn't able to reply earlier.
Everything looks great. Thanks a lot for all the trouble you have taken.

I hope to equal your professionality in the design and built of the filters.

Thanks again
Dick.
 
#339
Thanks Bob

I received the boards last night. Thanks very much for organising this and going to the considerable effort of mailing all of these out. The boards look very impressive from a design and fabrication view.

And to answer your question Bob, mine are destined for use in a two active setup. The amps are using Elektor modules (High End Amplifier 5/2005) but in bridged mode with massively increased power supply capacity. The speakers are planned to be a BG RD50 planar coupled with twin SEAS W22 magnesium woofers, crossed over around 500Hz. I am planning on investigating the worth of some shelving boost filters for both the bass and treble.

The design would be something like the attached file (a rough preliminary outline).

Nigel
 

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#340
Looks like a nice project Nigel.

Most speakers can benefit from some baffle step compensation unless they are mounted flush with the wall. At the top end, I guess it depends on your ears. I don't really hear up where the B-Gs start rolling off any more, but I do sense that there is something going on up to 18 kHz or so as long as I have taken my allergy meds. :xeye: Many switchmode power supplies drive me nuts with their whine. Go figure.
 
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