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RE: Bass alignment filter for B&W speakers

Posted by seancuster71@gmail.com (P) on April 2, 2025 at 18:34:44

In Reply to: Bass alignment filter for B&W speakers posted by Leo loves music on April 1, 2025 at 06:53:32:

The photo you posted just shows a toroidal transformer wired to the ac power coming into the case and does not show a bass alignment filter. If the case and transformer pictured is yours, you need to remove that conductive bolt that holds down that toroidal transformer. A Conductive bolt holding down a toroidal transformer is a no no !!! It can create an unintended electrical loop and act as a second winding and a conductive bolt can cause unwanted noise. Audiophile gear like amps use toroidal transformers because they are low noise. You can buy nylon nut & bolt that is nonconductive your transformer will thank you.

And why did you design the filter? All B&W 800 series were sold with the B&W 800 bass alignment filter. Unless you bought yours used and the filter was missing.

How do you know your filter is helping or hurting your B&W speakers? Design without measurements is a guess and will usually do more harm than good. when designing your active filter did you use a Butterworth alignment? What frequencies did you filter out in your design?

Do you think the bass filter will make more of an improvement than changing out the stock 35+ year old dried-up electrolytic capacitors that are in parallel in your crossover and due to age have lost capacitance more than likely 20% of their original value and are changing your crossover frequency and then there are the cheap polyester capacitors B&W used in series aka signal path. A recapping or popular crossover upgrade will improve the sound the bass filters are arguable many owners could not tell a difference with the bass filter or without.

If you're listening to Jazz and rock with no piano the lowest frequency your speaker will have to play is 40 HZ the lowest note on a bass. And the bass filter is filtering subsonic bass which is bass under 20 HZ and there is only one instrument that plays under 20 HZ and that is a pipe organ. So how effective could the bass filter be if none of the music you're listening to has subsonic frequencies?

I would upgrade that stock crossover or at very least do a recap.

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