Rotel RB-1080 Not Enough Power For Subs?

[cheekyfish]

I just bought a Rotel RB-1080 to power my two SVS CS-Plus 20-39's and I can barely get these subs to move. I thought 300 watts to each should do something more. Should I go with a different amp? I would like to stay around $1000. Any help would be appreciated.

[soundhound]

Somethin ain't hooked up or set up correctly.
The 1080 is 200 x 2 @ 8 ohm (assuming 6 ohm subs from the your 300 watts listed) which will make them thump................

[cheekyfish]

They are 4ohm subs. I seem to lack dynamics if that makes sense. I replaced a Crown XLS-402 with this and I know the Crown puts out a 100 watts more but the difference is night and day. It's not a placement issue either. The subs just don't move like they did before. I have to really crank the volume.

[Kevin D]

You're definitely on the low end of power. Even at 4ohms the 1080 is only pushing 330w to each sub. The 1080 is also not really set up with a higher input gain needed for running subs. You'll probably have to crank the sub output level on your processor to max and then probably still lower the output level on all other channels.

And even doing that might clip the input levels on it. The 1080 just isn't going to run as hot as a commercial PA style amp.

Just to give you an idea, I started off running my two CS+ 20-39's with the Samson S1000 (500x2 into the 4ohm loads). I wanted to go to Rotel amps like you did and got a RB-1091 (500x1 at 8ohms). The 1091 is 'mostly' stable at 2ohms so I ran the subs mono. This puts the output in the neighborhood of 1500x1 into both subs. I did have to crank the sub output level to get the same volume as before.

The sound was much improved, but running a 2ohm load with a high input level at extended volume was too much for the amp sometimes. I switched it out for a RB-1092, whitch is putting close to 1000 watts into each sub.

I still had to have the output level turned up more then normal, but now the SVS subs are down right scary now. Pretty much everything is just effortless now. I'm still searching for a track to bottom them out; something I could easily do on every amp before. I'm also looking to get those upgraded drivers they sell (mine are the first driver version).

So it's not just about the wattage figures when going to a residential style amp, but whether you have a hot enough input signal to drive it to those levels and if it can take that signal.

Kevin D.

[mjb]

Subs use a lot of power (at near DC) as they need to shift a lot of air. Using a high quality full range amp for a sub is not going to do anything justice.

[imbeaujp]

So it's not just about the wattage figures when going to a residential style amp, but whether you have a hot enough input signal to drive it to those levels and if it can take that signal.

Kevin D.

Hello Kevin,

I have the same problem with my RB-1080 to drive my 2 subs (4 ohms). The sub level is at MAX level on my RSP-1098 and sometimes I would like to have more sub when listening to movies...

Changing for the RB-1092 is an option. But what if I use another preamp between the RSP-1098 and the RB-1080 to add some gain ???

[shadow 8]

There is good reason why you should buy a powered sub since the amp is designed specifically for the speaker and enclosure used. The Crown is no doubt a better amp for this application than the 1080.

[Kevin D]

Hello Kevin,

Changing for the RB-1092 is an option. But what if I use another preamp between the RSP-1098 and the RB-1080 to add some gain ???

Then you will start clipping the input on the 1080. It will most likely go into protection mode, but in the least sound really bad.

If you wanted to try it anyway, car stereo shops will have some relatively inexpensive line driver amps for you to test with.

Kevin D.

[PewterTA]

You need to realize that most if not all SVS subs are pushed with a greater than or equal to 325w RMS Bash Digital plate amp. Most are 525 or 750watts.

The Rotel amps are not designed to drive a subwoofer with their power.

I'd either go with one of the plate amps from SVS or look at Partsexpress.com and pick up one of their plate or rack subwoofer amps.

[imbeaujp]

What do you think of the Behringer EP2500 ?

[BassThatHz]

I haven't tried these, but here are two more common brands:

QSC PLX3002
550Wx2@8 900Wx2@4 1500Wx2@2
Class H with Fans ($999)
Not designed for subwoofers

http://www.qscaudio.com/products/amps/plx/plx.htm

Velodyne SC-1250
1250w@8 3000w peak (mono?)
Comes with remote, microphone, 7-band DSP, low pass defeat, adj phase etc
Class D No Fans ($999)
Designed for subwoofers

http://www.velodyne.com/products/manuals/63-SC1250_Manual_lowres.pdf

http://www.audioholics.com/reviews/speakers/subwoofers/velodyne-sc-iw-in-wall-sub/sc-iw-measurments-and-analysis.html/?searchterm=SC-1250

[imbeaujp]

Hello I just found that there are 2 gain you can use in the sub configuration on the RSP-1098. The first one (sub level in the test tone menu) was set to +9 and sometimes it was not enough. I just found that you can add another +9 in the advanced sub configuration that apply to each surround mode. So I set +6 on that menu and +6 at the other and all is fine (total +12).

JP