Notch filter with baffle step compensation

Hi everyone,
I have built a sealed enclosure for full range 4 inch driver. i added 3db BSC filter in series with the driver and it sounds good. These are cheap full range drivers and sounds good at moderate volume levels. I want to add a parallel notch filter to these. Please advice me whether notch filter should be added before or after Baffle step compensation. Thank you.
 
I have built a sealed enclosure for full range 4 inch driver. i added 3db BSC filter in series with the driver and it sounds good. These are cheap full range drivers and sounds good at moderate volume levels. I want to add a parallel notch filter to these. Please advice me whether notch filter should be added before or after Baffle step compensation.

A parallel RLC is usually added after the parallel RL shelving filter; for e.g. John Krutke's B3 design Zaph|Audio -however, it's not mandatory.

Does adding a notch filter to BSC filter cause problems to the tonal range...

Only inasmuch as it will reduce output over a specific region. Tonality is primarily a product of frequency response and distortion / frequency / drive-level behaviour. Note that while you might electrically notch out a peak, the distortion products (both higher & lower in frequency) will still exist; a point that is often overlooked & one reason why mechanical solutions are preferred to such issues when possible.

...What I mean here is does either of the filter interfere with the functioning of other filter?..

In terms of the basic theory, not really, assuming you're working with the correct impedance loads and frequency response for the target BW. Keep an eye on physical positioning so you don't have issues with field interactions between the coils; see Troels's short page on the subject & stock electrical engineering texts: Placement of coils in crossover networks
 
If you are adding a notch consider also adding a zobel impedance leveling filter to make sure the notch hits the frequency range you want, might also make an easier load. In fact try it with just a zobel, might clean things up a bit.

PJN
I have been contemplating about adding Zobel for quite a while. Calculating the cap value is a major hindrance, Since i am not apt in measuring Ts parameters. I read somewhere that as a rule of thumb resistor value can be 10 ohms and cap value 100nF for a 8 ohm driver. How much of this is correct?. Can a inaccurate zobel network damage the output IC of an amplifier?
 

eriksquires

Member
2013-05-10 4:11 pm
Since you are running the driver full range, instead of a Zobel you can use a simple resistor across the inputs. 5W/60 Ohms or thereabout to prevent very large impedance increases.

In addition to being fewer parts, you have less chance of a new cap interacting in unexpected ways with the sound. I always suggest Mills for power resistors.

Of course, either solution will affect a tube amp more, but I've read of claims that controlling the maximum impedance at high frequencies also prevents ultrasonic oscillations. Either solution will work. Make sure you use a good n cheap film cap and bypass it for your use. :) The bypass is only a charm against ultrasonic oscillation. And any good film caps will do. Bennic, Dayton, Solen. Just bypass it. Total cost shouldn't be more than $3-4

Best,

Erik
 
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Thanks Eriksuires. The idea of connecting a 60 ohms resistor seems good to me and have just tried that. Presently playing around the values of components of the Notch filter. Like most cheap full ranges this 4 incher crackles at high volume levels. Will getting the right values for the Notch filter address this issue?
 

bsl100

Member
2017-02-17 2:25 am
Hi,

Planning a BSC and Notch filter for the RS00-8. The BSC Resistor and Inductor will be in parallel. Will the Notch filter Capacitor also need to be attached in parallel or after the BSC in series.

Also can anyone suggest the best BSC for the driver.

Thanks in advance.