Let us know how you make out and what adjustments you made to the basic circuit design.

Martin

But all drivers are not that bad! First of all, allow for proper break-in. The use the right enclosure. And the right amplifier (such as a low damping factor tube amp).

If using a SS amp (as I do on my FE168EZ), try a (series) 4 to 10 ohms non-inductive resistor. In my case, I noticed what seemed like a 6dB boost in bass, and a "magic" drop in low treb output, while retaining vry HF sound.

At the very low frequencies where the electrical impedance at the driver terminals is high due to the system resonance(s) and at the high end where the electrical impedance is rising due to the voice coil inductance, the series resistor has almost no effect on SPL. In the middle frequencies, a voltage division occurs between the series resistor and the driver impedance to shelve down the SPL output. So at the top and bottom end the SPL is not really changed, only in the midrange is there a reduction in SPL. The speakers efficiency is changed different amounts at different frequencies depending on the electrical impedance of the speaker. There is never an increase in SPL output.

You are depending on the drivers impedance curve to rebalance the SPL output. If you use a Zobel across the terminals and a BSC circuit (with parallel cap) in series you have a bit more control over when the SPL is reduced and then allowed to rise. This is the next level of refinement to just adding a series resistor and you should be able to make another improvement in performance.

Martin

• Quarter Wavelength Loudspeaker Design

Glad things worked out so well. The BSC circuit is such a simple method for adjusting the relative volume produce by the speaker at different frequencies. It rebalances the SPL curve. I agree with your comment that nothing is lost, nothing is added either, and as an additional benefit it helps smooth the slight phase shifts around the baffle step frequency. Unfortunately, the BSC circuit has a bad reputation and purists constantly criticize its use in full range speaker systems. They must like that very forward midrange sound.

Thanks for the feedback,

Martin

"ANother person saved!"

A new member of the super secret full range driver cult of the BSC filter. I hope the purists don't catch and subject him to a shouty piercing full range system running straight off the amp until he is reprogrammed.

Martin

There is some real truth in what you say, that loud midrange can really lure you into thinking the speaker is more revealing and dynamic. It can sound great, it sounds way different then anything else you have ever heard, unfortunately it is also not realistic.

Martin