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Help My wife bought me a sub

My wonderful wife bought me a used but well cared for SVS CS-Ultra subwoofer for Christmas, which was very cool. However, she didn’t know about passive vs. active subs and I don’t have an amp (the RDA-7 does not have a sub output) to drive the passive CS-Ultra. If I was going to buy an amp I’ve read that a Crown K1 might be a good choice, which I’ve seen used for around $700.

I have a dedicated room which is small, 12’10” x 9’ 5” x 7’ 10”. Mostly used for TV but want a high level of satisfaction for movie/concert video’s when I do watch. No critical music listening done since I have a separate room for my 2-channel for that. I currently do not have a sub but have been looking, just hadn’t pulled the trigger yet.

While I’ve read that the CS-Ultra is a very fine sub the drawbacks I see compared to active subs are no amp, no electronic adjustable characteristics like phase, gain, EQ, etc.

Active subs I had entertained were the SVS PC-Plus or PC-Ultra, Onix Rocket UFW-10, Hsu VTF3 Mk 2, or something along those lines. I have a balanced output connection from the RDC-7 processor and would like to use it if possible.

I’m thinking that if I did sell the CS-Ultra along with the money I didn’t spend on a Crown K1 amp I would have plenty to buy a really nice active sub that would give me all the electronic adjustable bits I think I need.

The components I’m using are Integra Research RDC-7 processor and RDA-7 amp, NHT M5 L/C/R speakers. No surround speakers yet.

What to do? Any advice or suggestions would be most welcomed!
128x128mr_slate
jim_swantko
301 posts
 
I'd give SVS a call (e-mail actually) and see what they recommend. They are very good guys to work with.

Jim
cadet1
50 posts
 
If you are using no surrounds,why don't you just use one of the RDA 7 channels to drive your sub. Using your RDC 7 to control the crossover freq,level,distance, ect should work very well. I do the same thing with the third channel of my proceed HPA 3 and it works great. Probably MUCH better than the cheap plate amps.
tantra
31 posts
 
Another idea is to buy a Gallo Subamp. This is a very flexible amplifier for driving a passive subwoofer. What ever amp you use to drive the sub, I would recommend using the speaker-level outputs of your main amp as input(s) to the subamp. This gives the best integration.
artizen65's avatar
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artizen65
273 posts
 
MrSlate,

After doing some homework. I have come to the conclusion that you should atleast try the sub in your system. The RDC-7 has a crossover output 40hz to 150hz in 10hz increments. I couldn't find on their website the information about adjusting the gain but I bet it will. So that gives you 2 out of the three no phase control but you may find that you don't need it.

Ok the sub is ported so you shouldn't need gobs of power. As was suggusted before take the sub output to one of your rear speaker channels on the amp. I couldn't find the impedence on the sub but if it is 8ohms you still have 150 watts supplied to it.

So go find some cheep 12ga. speaker wire connect up the sub place in your listening possition walk around the room and find where you get the best bass. Place the sub there sit down and have a listen. I think you will find you don't need the phase control.

You have everything you need to try this experiment except maby the speaker cable. You can still add 2 rear speakers in the future for 5.1 and you are good to go. As there is no 7.1 software out there you should be set for some time to come.

Let your wife know she did a good thing and give it a shot.

Good Luck.
mr_slate's avatar
mr_slate OP
15 posts
 
Guys,

Thanks for the wake up call. I guess when I saw no subwoofer listed on the RDA-7 amp only surround speakers I didn’t think I could use the amp. I’ve made up the cables and will try it out. Since the RDA-7 has 150w into 8 ohms and 300w into 4 ohms I should have enough power. Thanks for your help!
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