What do I Have?

[dstamand]

AllenCT wrote:

"The crossover for those speakers consisted of a 500Hz crossing point and high frequency shelving control at 8 ohms 12 db/octave slope. The Altec 30923 Attenuator/Equalizer network was part of the crossover system along with the N501-8A."

I understand what the N501-8A does in terms of being a filter crossing over at 500Hz. Would you be so kind as to explain the use of the term "shelving"? I have seen it used several times in various posts.

Thank you,

Dwight

[AllanCT]

You probably could get 105 db or so out of them in a close listening position.

Good thing tube amplifiers usually clip softly.

The 411-8A based studio monitors really like lots of power.

[AllanCT]

I'll quote Altec since they are a bit smerter than me.

"To obtain the extremely fine performance parameters of the 411 series, Altec gave up approximately 6 db in output- compared to the high efficiency units. With today's values in amplifier power, compared to a few years ago, this compromise is well within the reach of every audio user. Further overall system performance is improved through the use of system equalization. When the 411 series low frequency woofer is matched to a "Voice of the Theatre" high frequency system, there is a mismatch in system efficiency. In Altec factory-built systems, we use an attenuator/equalizer network which shelves the efficiency of the "Voice of the Theatre" high frequency system to match the efficiency of the 411 woofer. Further it provides shaped shelving for the flattest possible overall response. These attenuator/equalizer networks are available for the home builder, and are listed on Altec price lists."

Shelving is just attenuation I believe and shaped shelving is equalization and attenuation in simple terms.

Midrange of the 511 horn and drivers is cut back and the high frequencies are left flat to achieve the best response is how those networks worked I think.

Never used one at home, I just tri-amp. with a JBL slot driver on the high end above 7K and use conventional 1/3 octave equalization where needed.