AR-3a crossover question

[ninohernes]

My AR-3a's are lacking bass response. Everything below like 90hz sounds muddy, and there is no bass definition. Everything below 60hz is non existant. Bass drum hits are gone, and stand up bass sounds very thin. Right now, my AR-2's have deeper bass! What is wrong? I am thinking it is the 150uf electrolytic.

[Carlspeak]

>My AR-3a's are lacking bass response. Everything below like

>90hz sounds muddy, and there is no bass definition. Everything

>below 60hz is non existant. Bass drum hits are gone, and stand

>up bass sounds very thin. Right now, my AR-2's have deeper

>bass! What is wrong? I am thinking it is the 150uf

>electrolytic.

Joe:

Have you carefully inspected the surrounds for foam rot or small tears?

Carl

[tysontom]

>My AR-3a's are lacking bass response. Everything below like

>90hz sounds muddy, and there is no bass definition. Everything

>below 60hz is non existant. Bass drum hits are gone, and stand

>up bass sounds very thin. Right now, my AR-2's have deeper

>bass! What is wrong? I am thinking it is the 150uf

>electrolytic.

Joe,

This sounds like an out-of-phase problem to me, either with a speaker or with the leads to the speakers. Does the bass sound thin when you play through both speakers? If you just play one, do you still have thin bass or nothing below 60 Hz? Be sure that when a positive signal (you can use a flashlight battery) is put to the "2" terminal on the back of both speakers, the woofer cones move *out* or away from the cabinet. Both speaker *must* be in phase; otherwise, you can have thin, muddy, and especially a dose of "diffuse" bass. Not good. Also check to be sure you are wired from the amplifier with positive leads going to the same terminals on each speaker. It is easy to overlook this detail -- I've done it many times and had to backtrack. Be certain that your amp is compatible with the AR-3a's somewhat difficult load. You could have an air leak, but it would have to be pretty atrocious to cause such a serious bass drop as you describe.

--Tom Tyson

[ninohernes]

I have checked all of that. My amp (Adcom GFA-5400) is plenty capable of driving them. It drove my AR-3's just fine. I am stumped, I have no idea what is causing this drop in bass response. I have heard many pairs of AR-3a's and none of them have exhibited these symptoms. I also removed the woofers and made sure that the leads were correct, and they are. The woofers are fine, I tested them in a pair of working AR-3 cabinets that I have, so the drivers are fine. The only thing left is the crossover.

[soundminded]

Check to be certain that the woofer is wired in parallel with the capacitor and in series with the inductor. If you got it backwards, the capacitor will act as a high pass filter and I would expect you to get just about the effect you reported. Good luck.

BTW, there is an interesting AR3a crossover rebuild article at

http://www.humanspeakers.com/

[ninohernes]

Ok, I will check.

I do get decent bass response if I boost the bass control allmost all the way up on my preamp, but obviously that is not normal.

[ninohernes]

Does anyone have a drawing (not a schematic) of the AR-3a crossover, similar to the Layne audio one? I am not good at reading schematics, and a drawing, with the original components would be nice for me. The problem with the layne audio drawing is, that it is with modern components, which are wired differently then the old ones (like capacitors, the old ones have three leads, and the new ones have the standard two)

My AR-3a's are early ones.