FAST, LOW RESONANCE subwoofer to go with Dynaudio Confidence 5?


Hi! I've recently purchased a pair of Dynaudio Confidence 5.

I enjoy them very much, except their bass is a bit shy. I've tried many amps, including Mcintosh monster amps (>1000wpc) and the frequency response stays the same. In my room it is the shape of a flat hill. Low frequency is rolled off of about 5-10db.

The quality of the bass is extremely good ------ However the quantity is just too little.
I tried my friend's REL T7i --- and played around with position, direction, all settings with my MiniDSP measuring mic. I got the best out of it in my current room --- but still doesn't integrate with the Dyn's bass, I think the C5 really have one of the cleanest and fastest bass in the world.

Are there any other subwoofers that would go well with them? apparently Dyn's own sub such as sub 3 and sub 6 would be a good bet but I just want to see if anyone knows another option, thanks all
qyy920
The REL T7i is a home theater sub $.  Boom! Boom!  You get what you pay for. Their S/3 or S/5 will do the trick but $$$.
State of the Art bass costs only about $3k. Or less. This does however call for a little outside the box thinking and learning to understand that four of just about any sub beats one of just about any sub. Hands down. No contest.
Hi, TBI subwoofers are an excellent choice for clean fast bass. I used to use a pair in stereo with Reference 3A mm De Capo's and they just made my speakers sound like they had deeper and room filling bass!           The subs disappeared and created an organic sound that you have to hear!              I used the speaker taps on my amp so the sound would be consistent. I sold the De Capo's and used Sonist Concerto 2's and the same magic happened.      But when I traded up to Concerto 4's that go down to the mid 20's, I had to sell the subs to finance the purchase and still wonder how those subs would sound with them. I just recently retired and cannot afford any more gear but I am VERY happy with my system.
good advice! 4 is probably too much for it but I'm happy to start with 2 subs. 
The REL T7i is a home theater sub $.  Boom! Boom!  You get what you pay for. Their S/3 or S/5 will do the trick but $$$.
I didn't know that! Apparently a lot of people just praises how good the Rel subs are in an 2.1 system and for music listening but I wasn't aware such difference between the real models. Ok I'll start looking around for them
Idk, I think with that caliber of speaker you might consider a dual sub setup using JL Audio F112 version 2 to get really impactful, deep and quick bass. 
Isolate the subwoofer! Less mechanical feedback. Lower cabinet resonance. Better bass slam and better detail and articulation. Problem solved! 🤗
"Are there any other subwoofers that would go well with them? apparently Dyn’s own sub such as sub 3 and sub 6 would be a good bet but I just want to see if anyone knows another option, thanks all."

Hello qyy920,

I believe a good solution for any room and pair of main speakers would be to utilize at least a pair of subs in your room. You could use a pair of Dyn’s own Sub 3 ($1,799 each=$3,598/pr.), Sub 6 ($2,799 each=$5,598/pr.) or a pair of REL T9/I subs ($1,099 each/$2,198/pr.) but I would suggest a pair of SVS PB-1000 subs (currently on sale for half price at $499 each/$950/pr.) will perform just as well at a bargain price. Here’s a link to these subs:

https://www.svsound.com/products/sb-1000#tab-2

Despite the bargain price these are very good quality subs that have all the necessary controls such as line level and speaker level hookup options along with controls for volume, crossover frequency and continually variable phase settings. Like the other subs, you have the option of using the built in high pass filter to restrict the bass output of your main Confidence 5 speakers or running them full-range and supplementing their bass with the pair of subs below a specified bass frequency through low bass filters on the subs.
I wanted to make you aware of these bargain priced subs but I’d also like to know more about your room and system to better tailor my advice to you like:
1. Your other system components by brand and model number.
2. Your exact room dimensions.
3.  Where your main speakers and gear are located, along the long or short wall.


Thanks,
Tim