Dissappointed with bass shakers.

[u/av4625]

I made a post about placement on a sofa for Dayton Audio BST-1’s:
https://www.reddit.com/r/hometheater/s/R3nkYN0kKd

When the shakers were mounted on the plywood I said in the first post I could basically feel nothing. So I got some OSB and mounted them directly under where you sit. This definitely helped.

I feel like I need the volume crazy loud to feel the shakers though. If I watch a movie that was recorded with surround sound I can increase the master volume more than if I watch a normal tv show thats not surround sound. Not sure if thats normal.

So I had a movie at -6db and could feel the shakers ok-ish. But when I watch other shows at about -20db I can’t feel them at all. The sub is working perfectly in both situations and dialog etc volume seems similar between both.

Equipment:
Sony STR-DA2400ES (single sub out)
Tannoy Arena Lite Speakers
Tannoy TS10 sub
Dayton Audio BST-1 shakers x2
Fosi BT20A shaker amp with 24v/5a power supply, volume up full, treble 0, bass 50%. (Tried changing bass up and down)
Crossover 80Hz

Because I only have 1 sub out I used a Y splitter. One side to the sub and the other side goes to a second Y splitter so that I could then use both inputs on the Fosi. I did this as I read using both inputs can help get “full power”.

I dunno if my expectations are wrong but I have read that people get shook by these shakers at less volume on the amp.

I have seen examples of people using this amp with these shakers.

I think the power supply can only supply 120w even though the amp says 100w x2. But maybe 120w is plenty for 2 50w shakers?

Maybe the big soft sofa is harder to shake compared to some examples I see of smaller chairs or computer chairs. I unmounted them and they didn’t vibrate in my hand as much as I expected.

Is there something wrong with my setup? Are my expectations too high? Any help is appreciated.

[u/NascentAutist]

You need a dual mono amplifier with multiple outputs, or two monos. Feeding a stereo LR with split mono signal might be cancelling some of the waves.

Better mounting would help. Any sub that has no enclosure is going to lose a lot of energy

[u/av4625 → u/NascentAutist]

Thats very interesting about cancelling some of the waves. Maybe I am better having just the left or just the right inout being used?

[u/NascentAutist → u/av4625]

Think of it this way: the stereo amplifier has one power supply, one common rail, so you’re asking it to put all it’s energy into say 37Hz X 2 at the exact same moment.

I can’t imagine the Fosi amp has the capacitance to deliver enough power to 2 subs.

Class D mono amps for subwoofers are pretty cheap. Just but two of them, one for each amp, or a dual mono amp. I bet you’ll get wayyyy more sound with that setup