Altec A7 Measurement Query

[ngccglp]

Hi,

Does anybody knows the exact distance from the front edge of the 828 bass cabinet to the straight edge of the 511B horn? I'm trying to get the horn and bass to be in phase. I'm using the 802 compression driver.

Thanks.

[ngccglp]

Hi,

Appealing again to Altec A7 owners. I need the distance from the front edge of the cabinet to the straight edge of the 511B horn. My A7 did not come with pre-drilled mounting holes. Compression driver used is 802.

Thanks.

[louped garouv]

in about two weeks....

I will post a reply then.....

until then the only thing I can offer is this....

[louped garouv]

http://www.wmeckle.com/ALTEC/Index.htm



Quoting from an Altec service bulletin (slightly edited): "Align the voice coils of the high and low frequency drivers in the vertical plane. Mechanical alignment is only the first step in the phasing of loudspeaker systems at crossover; there are certain to be phase shifts in both high frequency and low frequency drivers that must be compensated for. Once the voice coils are aligned, deliberately wire the high frequency driver with reversed polarity. Set up a Sound Pressure Level Meter (SPL Meter) at the listening position where you can see it while sliding the high frequency horn back and forth. In this situation, an assistant may be able to move the high frequency horn while you read the meter. Playing pink noise (several test CDs have pink noise tracks) through the system (either wide range or limited to a band in the crossover region), slowly move the high frequency horn until the crossover notch appears in the SPL meter. Watch carefully: there is an area only a couple of inches deep in which the notch appears. Position the high frequency horn so that you show the deepest notch you can get. The depth of this notch is a figure of merit for phase matching at crossover; 6 or 8 dB is excellent. You will notice that moving the horn only one-half inch either way will reduce the notch by several decibels. Now, reverse the polarity of the high frequency driver and the system will be phased correctly at crossover."

[ngccglp]

Thanks LG.

Do let me know what your position of the horn is when you get your A7.

A friend informed me that the voice coil of the compression driver should be about 19.3 inches from the front edge. Not sure how he get the number. I'm using this position until I hear from you.