Axiom Home Page Forums General Discussion Technical Questions EP subs sucking life (gain) out of the 350's....

Mine never has been daisy chained, there's a splitter at the AVR and from there each sub cable gets plugged into a wall plate with individual cable runs going to each subwoofer location throughout the room.

I've never though too terribly much regarding the 600 and the 350 not playing well together because I knew bringing the old 350 into the mix was like bowling with a marble but if there is a problem with the 600's amp I sure would like to have it rectified.

Yeah, this seems to match what Randy is seeing as well, and it's one of very few explanations for how a sub on one side of a splitter could affect the output level of a sub on the other side of the splitter.

Here's a question... don't balanced inputs normally have a much lower impedence than single-ended inputs ? My mind keeps supplying "600 ohms" as the answer, even though I haven't asked it the question yet

Andrew, using a "Y" at the receiver sub out is electrically equivalent to using a "daisy chain" through the sub. The sub arrangement is an internal Y with one branch going straight through to the next sub and the other branch going into the sub amp. That's why Randy got the same result with both configurations. In both cases the two sub amplifiers are connected in parallel with the receiver preout, dropping the input impedance to 1/2.

This would exacerbate what may have been an unusually low input impedance on the EP600 amp, as Mojo and I had discussed. The output impedance of the preamp and the input impedance of the sub amp are in series and form a voltage divider. Unless the sub amp input impedance is much higher than the output impedance of the preamp(as was said, at least 10 times is suggested)a substantial drop in voltage from the preamp occurs, with a loss of volume, when the low impedance sub amp is connected. The modified amp in the EP600 may have corrected this low input impedance(if it in fact existed)and now the connection creates no significant volume drop. The change to a 150Hz brickwall filter instead of 100Hz would allow for better blending with small speakers that need crossovers above 100Hz, but wouldn't in itself change the input impedance of the amp. Randy might check with Axiom as to the possibility of installing the modified amp.

This 600 should have the modified amp. Less than a year ago, Axiom sent me a new amp as my original amp in the 600 was defective. When I would adjust the gain knob even the slightest, it would jump in output like 20+dB's. Also, if I pushed on the amp plate in a couple of locations, it would do the same thing. I believe this new amp does not have the brickwall filter.

Thanks John, you are most certainly correct. I need to re-open my text books.