Avatar B212 Horn Control Mod

[freaksho]

since no search function . . .

 

i vaguely remember a thread a while back about a mod for the avatar b212 horn control to make it less harsh sounding (as it is i can barely turn it on before it gets unusable). does anyone know anything about this?

[J.]

The mod is simply adding an appropriate high pass filter to the horn. The "crossover" that comes stock with the Avatar cabs is simply a capacitor wired inline with the foster horn, providing a 6db per octave rolloff below the crossover point (which is 3500hz if I remember correctly). Simply stated, this slope isn't steep enough to give proper protection to the horn, resulting in 'harshness' as the horn tries to produce frequencies that are at (and below) it's lower limits. With the simple capacitor acting as the HPF, the horn is only down 6db at 1725hz and is still getting a fair amount of power.

 

In order to get better performance, reliability, and sound from the horn, a better HPF with a steeper slope is needed. I think something along the lines of a 3rd order (18db/oct) or 4th order (24db/oct) would suffice. If you do a search on talkbass.com you'll see that a lot of folks there have made their own linkwitz-reilly 24db/oct high pass filters for their Avatar cabs and significantly improved the performance. In fact many even lowered the crossover point to 3000hz with good results - you can do this because with such a steep rolloff you're still going to have much, much less power going to the horn at 1725hz with a 3000hz 4th order than you would with a 3500hz 1st order.

 

If you're not up to building your own high pass filter, I'd suggest installing this one from Eminence:

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=290-602

 

It's a 18/db per octave HPF with built-in bulb protection. Replacing the existing cap with this crossover with definitely improve the horn's performance and reduce harshness.

[freaksho]

awesome.

i'm not sure whether i'm up for building my own - i'll do some looking into it. but i'll definitely do something one way or other.

thanks.

[bassman1956]

Or, you can use one of them listed on this Parts Express page that also give you attenuation of the horn.

[John S. Shinal]

I ordered an Avatat 12 the other day, and noticed that he has recently upgraded his crossovers to a 12dB/octave unit that looks like it may address some of your concerns. Check with them and see if they will sell you an upgraded crossover.

 

Many towns have a local company that custom builds crossovers (like a speaker recone/builder shop). Parts Express, Eminence, US Speaker and Carvin all sell crossovers that may work for you.

[mlwarriner]

 

Originally posted by John S. Shinal I ordered an Avatat 12 the other day, and noticed that he has recently upgraded his crossovers to a 12dB/octave unit that looks like it may address some of your concerns. Check with them and see if they will sell you an upgraded crossover.

 

 

email dave and tell him you want to buy a new jackplate for whatever cab you have, at whatever impedance. they're $30. simple installation. comes with the new crossover.