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!
That's a small room to successfully integrate a sub if you want more than boom. I like the HSU alot. Not expensive and very tuneful when tuned in properly. You also might look for one of the older NHT 10" powered subs which won't
overdrive the room.
Your wife got 'close' picking a brand you were considering but a passive version. IMO the fact that she bought you stereo equipment for xmas far outweighs all the considerations you mention in your email and that the first respondant anyway responds to. Make it work--any old used ss amp should do the trick. Get an integrated one and run the tape out from your preamp to it, adjust the gain as needed, decide on phase with speaker lead swaps and leave it that way. Many HT receivers have a high level sub out with xover. Maybe that plus a ss amp. Find an xover stand alone. Use your ingenuity and be grateful. That's a bigger challenge than selling the thing and getting exactly what you think you want. (Good luck)
I'd keep it because the fact that your wife bought it for you, and because it's a great sub.

I would pick up a Crown amp and maybe add a Veoldyne SMS-1 down the road... it will give you 1000 times the flexibility/performance that any "built-in" stuff will.

Congrats on a cool wife!! :)
I run an REL strata 3 in a similarly sized room and it sounds great. However to make any sub sound great I've found it has to be out towards the middle of the room. At least the REL doesn't look too bad away from the room periphery, especially if you can get one of the wood finish versions.
The Velodyne SMS-1 is a very good idea. Why didn't I think of that !?
Does you wife have a sister I could marry?


Thanks for all the thoughtful responses. I knew I was going to get some great help and ideas.

Here is one thoughtful response about passive vs. active subs: “There is one big advantage with passive subs, and that is placement. You can move them around the room to find optimal placement (which is critical for subwoofers) without having to worry where you are going to tap the power for the amp and also getting long subwoofer interconnects.” That makes sense and helps push this question into keeping the CS-Ultra sub plus it was a present from my very cool wife. Now, how best to power it?

Many ideas have come in for that which I really appreciate. I really didn’t want to have several boxes although “component” sourcing often lets you pick the best of breed and really get the best out of your components. The Velodyne SMS-1 looks very cool and I bet works really well although at $749 MSRP that’s cutting into my budget and I still need an amp. There are several BASH amps available with EQ/phase/gain etc. controls that might do nicely.

Here is one that was brought to my attention that looks very nice and seems to have all the controls a sub would need. Any experience with this Class D amp?

I’m thinking the ADA600 for $549 would drive the CS-Ultra just fine in my smallish room although it’s back ordered at this moment.

Or buy a replacement SVS BASH amp?

This amp from Parts Express looks pretty good and seems like a good value:

O Audio might be nice -

Or what else would you do different?

Thanks for all your suggestions!
Sufentanil - all the girls are married but I got the pick of the litter!
I'd give SVS a call (e-mail actually) and see what they recommend. They are very good guys to work with.

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.
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.

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.

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!