Common Bass channel XO

[Geoff H]

I set up was to be a temporary crossover in order to work on my bass amp, which has a few issues.

I think the temp xo will stay until I build a new 3 ch amp.

The auto transformers have 2 functions. 1st, to pull the spl of the main wide range units down about 6 - 8 db to match the bass. 2nd, utillising the primary inductance as part of the crossover.

The result is smoother bass freq resp - one of the issues with the bass amp and xo, and a bonus or two, improved transients and yet better imaging. And I think more headroom.

I am only using BP electrolytics at present. Checking tomorrow for the largest motor run cap I can get.

The transformers I am using are ex Martin Audio. I would think high quality 100 v line trannies could be used, just ignore the primary.

The value of C1 is set for an XL of 8 ohms at the desired xo freq. I haven't done any measurements yet, just enjoying the music.

Geoff.

[Geoff H]

Here's a second version. It doesn't attenuate the wide range, and presents the 8 ohm bass speaker as a 4 ohm load to both channels.

The transformer I used for T3 is one I rewound several years ago as 2x13.5 volt bifilar wound for a battery charger. Its about 350VA.

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Insulate the primary if you try this. It will generate mains level voltages.
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Edit. Got my ratios wrong. The Z at the centre tap of T3 is 2 ohms,
presenting a 4 ohm load to the amp per channel.

Geoff.