SVS and Adcom Amp Question (1 Viewer)

[Terry Flink]

I am powering my 20-39CS with an Adcom GFA-555II rated at 200wpc into 8 Ohms. Does anyone know what the amp is rated at into a 4 Ohm load? I am currently using one channel to power the sub, but the amp is bridgable. I just don't want to "over power" the sub. Thanks for the input.

 

[SVS-Ron]

Terry,
As long as you calibrate properly you won't overpower the sub (hey, if you ever bottom out you just back off a few dBs at least for that movie and that watching level).
You could well "over draw" the amp though by bridging it. It might not be rated for a 4 Ohm load when bridged, but if it is it'll probably be around 500 watts. Since the SVS's impedance is dynamic (as with all speakers) according to the frequencies involved your amp might well do fine even if it's not rated for 4 Ohms. Just proceed with caution at first and make sure it doesn't get excessively hot or shut down.
P.S. I'm sure Adcom can tell you the specs on the amp.
Ron

 

[Terry Flink]

Thanks Ron! BTW I was stationed at Carson 89-93. Wish you guys were around back then. Would love to see you in action.

 

[Shade Watson]

Terry,
The GFA-555II is rated at:
200W @ 4ohms
325W @ 8ohms
600W @ 8ohms bridged
850W @ 4ohms bridged
One channel should do fine, both channels bridged even better. I would try the bridged mode. The amp has 'Thermal Protection' in case the load proves to be to much.

 

[Mark Hayenga]

Shade is correct. Adcom also recommends the use of a cooling fan if running it bridged into a 4ohm, which supposedly is available from their service centers. I've bridged mine into 4ohms without the fan without any trouble, but YMMV.

 

[Aaron E. Smith]

I'm using an Adcom GFA-555 to power my SVS, so I'm interested in how you like the results of your pairing the SVS with the GFA-555II!
One additional note: should the GFA-555II power ratings be:
200W @ 8ohms
and
325W @ 4 ohms
Not the other way around?
------------------
- Aaron
"Some mornings, it's just not worth chewing through the leather straps"
-Emo Phillips

 

[Terry Flink]

I replaced a Def Tec PF15 with the 20-39CS several months ago. I have some favorite DVDs and every one without exception had bass material I never heard/felt before. In some cases, like Saving Private Ryan, it was a reinforcment of what was all ready there. The final scene as the German tanks roll into town "moved" me and I could feel the concussion of cannon fire like never before. Other DVDs revealed more subtle bass that I never new was there.
I did try the amp bridged, but the sub "bottomed out" on the opening sequence of Toy Story 2. There was also a noticable increase in the heat output. I have been running the sub on a single channel and it sounds fantastic. The best way to describe the difference over my old sub is not necessarily what you hear, but rather what you feel. I will probably add a second 20-39CS and use the second channel for power.