Altec High Efficiency Horn Speakers

Speakers For SE Tube HiFi Amplifiers

As a builder of low power LOW DCR SE amplifiers, I need the most efficient high quality transducers to maximize the power potential of my circuits.

That is why I choose Altec Theater Products and adapt them for use in a domestic listening environment.

My personal system uses Altec 414-8B 12" Alnico magnet drivers in 2.6 cubic foot enclosures tuned to about 40Hz.  The 414-4B runs full range with no crossovers out to 3kHz and begins rolling off.

An Altec 811B  sectoral horn with 808-8B compression driver crosses over 1st order  @ 6.5KHz with a single oil cap as per Joe Roberts .  

A Crites 3636 autoformer provides a -3dB pad to level match the 414-8B to the 811B horn.

Finally,   a Mirage BPS 150 bipolar subwoofer fills in the last few octaves from 80Hz down.

The resulting system is fine sounding and adaptable to most music genres.

IMO, get the biggest best Altec system within budget and space considerations.

DT 667


High Frequency Horn Attenuation

Crites 3636 Autoformer

I have been using a Bob Crites 3636 autoformer in my Altec horn system since December 2018.

The autoformer would replace a typical  L-PAD to provide level matching between the horn and midrange or low frequency drivers in a multi-way speaker system.

The chart above provides values for reflected Z if the crossover cap is placed before the autoformer.

The impedance can also be changed by paralleling a resistor across the autoformer input terminals.

Or move the crossover cap between the autoformer and horn driver and the crossover point will not change with varying attenuation levels.

Bob Crites Speakers