Help remove baffle step circuit from RB XO

[rhapsodee]

Hi,

I have been enjoying my recession busters for the past 2 years, however i cannot help feeling that it needs a bit more baffle step compensation. I also built a rather narrow baffle for the speakers, which i'm sure made it worse.

I'm planning to add a 0.5 woofer with a 1st order LP rolloff to do the BSC duties. The 0.5 woofer will have a separate channel of amplification. Therefore, I would like to remove the BSC in the original XO. Hopefully this will also regain a bit of the midrange and tweeter sensitivity lost due to the BSC padding.

I have read that the BSC is usually not a discrete circuit that can be just removed. Looking at the crossover with my novice understanding, i'm not sure where the BSC is being implemented and how to change it.

From reading another post, the 1mH induction in series with the woofer seems to have some contribution to the BSC, as well as the amount of tweeter padding. I thought the 1mH series inductor is for part of the woofer low pass?

Thanks in advance for all the help!!

 

[sreten]

Hi,

The RB's are limited in that Madisound reused as many components as
possible for the surplus circuit board the crossovers are based upon.

By far your simplest option is passive line level EQ, conversion to a 2.5
way will change all the crossover components. The easiest way of doing
line level EQ IMO is adding a resistor and capacitor to the feedback loop
of the power amplifier, done in a way that is easily reversible.

rgds, sreten.

 

[PeteMcK]

I doubt there is any BSC in the original xover, just leave them as-is and try a 1st order
PLLXO for your .5 woofer at the baffle step freq (or a bit lower, tweak to get the balance you like): Passive Line-Level Crossover

 

[rhapsodee]

Thanks for the feedback. Adding the 0.5 woofer with a PLLXO and tweak to taste was what i had in mind.

I actually forgot to include the attachment in my opening post. From the graph of the frequency response, there appears to be approximately a 2dB BSC, 91dB from about 80Hz to about 89dB flattening out at about 300Hz.

I presume if this BSC is removed, i can gain about 2dB efficiency? According to Sreten, this would basically mean redesigning the entire crossover? Looking at the XO in the attachment, can some tweaks be done, ie by reducing the inductors (unwinding some coils) or reducing the tweeter padding resistor to reduce the ~2dB BSC?

Thanks.

 

[sreten]

I presume if this BSC is removed, i can gain about 2dB efficiency? According to Sreten, this would basically mean redesigning the entire crossover? Looking at the XO in the attachment, can some tweaks be done, ie by reducing the inductors (unwinding some coils) or reducing the tweeter padding resistor to reduce the ~2dB BSC?

Thanks.

Hi,

Due to the L-pad on the tweeter you can lift the treble easily.
You need to chsnge both resitirs to keep impedance equal.

Unwinding the bass coil would probably work for less BSC but I would
presume a different value capicitor/resistor combination would be
needed to keep the c/o point the same. Use a Sim ? (Tina Ti ?)

rgds, sreten.