Were to wire BSC in 12db LR LowPass filter?

[thunk303]

Hello all...

Since my last thread my MTM has moved ahead with all your help at a steady rate with each new XO build reaping fantastic sonic rewards....but

I'm using a 12db LR filter on my dual Peerless 850439's @ a freq of 2k with great results but when adding my 4 dB BSC into the circuit I'm getting enhanced bass but electrical confusion (me not the speaker, it sounds better).

If I add the BSC before the LR will i simple be changing the series LR coil value and adding resistance?

If I put the BSC after the LR will i be creating an 18db LP filter?

Were is the optimal spot for the BSC in this situation?

Or should i simply () be integrating the BSC and LR coils into one value and adding the appropriate resistance in parallel?

I am obviously missing the electrical point of how this actually works so please feel free to humor me.

Cheers all for any enlightenment on the issue... Dean

[PeteMcK]

if you're applying BSC to both Ms, put the BSC before the LR. If you put it after, the LR will be working into a different impedance. You can combine the BSC & LR coils.
If you're applying the BSC to only one M, then it will need to go after the LR and before that M.
MJK & Rod Elliot have good pages on BSC (although Rod's solution is line level)

[thunk303]

G'day Pete..

And thanks for the reply.

I am thinking at this point that we are moving into software territory in regards to calculating combining BSC and LR coils to achieve both with one coil.. but

Do i simply add both coil values? 0.76mH (LR) + 0.63mH = 1.39mH + x Ohms resistor

Do I only use the higher/lower Value? Or something in between? say 0.7mh + x Ohms resistor?

I haven't got any software at this point unfortunately so I'm just after a rough rule of thumb to start experimenting?

Cheers again Dean

[thunk303]

This is a link to my original thread for this project that has all the driver specs.

MTM - Stage 2 - Finalizing XO before build and need HELP :)

Dean

[thunk303]

And this is an image of the current xo I am using = LR @ 2k

If this is fine then so be it, like I said it sounds great.

But for the sake of fewer parts I'm wondering if I should be combining the BSC and LR?

Cheers all
Dean

[infinia]

If you are designing from the getgo then yes they are usually combined. If you have an existing design and are adding BSC, the parallel RL network is useful being in front of BOTH LP and HP networks.

[thunk303]

Hey Infini...

Sounds like im on the right track, do you know how i combine them?

Cheers
Dean

[infinia]

Lnew = L1+L2 dropping R2 because increased padding is now on the HP section. What's up with the zobel on the input side, usually if needed is on the output side of the filter.

[thunk303]

Hey mate, thank you for the help.

I was thinking with zobel to flatten the impedance then apply the filter but now that you mention it that would be *** about
Ill change it to the output side so the LR see a flat speaker+zobel impedance.

I would guess that the existing BSC and LR as is will be added anyway so removing the R from the bsc will do the trick

Cheers again..
Dean