Preamps

ozzy
I just contacted Audio Research about your statement that the ARC preamps having issues with subwoofers

ricred1 OP
I can understand "they" may have, as AR pre’s being tube are output capacitor coupled, are used to seeing tube poweramps of up to 100kohm input, and many subs have a very low input impedance 10kohm
  
You need a big output coupling cap if you want to get down flat to 20hz with 10kohm input, and they may not be big enough.


And I just looked your sub is 10kohm input!!


Cheers George

ozzy,

AR told me that their preamps have two inputs so it should have no problem driving an amplifier and subwoofer, but based on the low input impedance of the subwoofer many say it isn't optimal from a technical standpoint. The guy I talked to at AR agreed that it may not be optimal. 

georgehifi, ricred1,

Thanks for the information. But since the subs are self powered I don't see how the preamp output impedance can affect the sub. Also, the JL subs have a mic/calibration system, that would seem to me it would compensate for any possible low bass rolloff. Now, if having the sub connected affected the performance of the main amps then I would be concerned.

ozzy

But since the subs are self powered I don't see how the preamp output impedance can affect the sub.

The AR preamp with output coupling cap, has to drive not only your main amp input impedance, but also the 10kohm of your subs amp even though there are 2 outputs, and this could be the problem, the output cap in the AR  "may" not be big enough as explained in my last post, and cause a premature rolloff of the low frequencies, so the sub may not go down low enough.

Cheers George 

Vac