Subwoofers going into standby with low volume listening (New Integrated Amplifier).


Hello,

Just got a new Integrated amplifier (Technics SU-R1000) and have dual stereo subwoofers connected via the amplifiers preout R/L RCA connections (RCA Y-splitter at each Line In R/L connection) on my KEF 12b sub's.

While listening at low volume my subwoofers keep going into standby mode and turn off. The subwoofers also don't sound very lively at all. I have the crossover and volume at "Max" just to try to hear them and they don't sound loud or overly bass heavy at all, which at max volume would've sounded very over the top with my previous integrated amplifier. I've adjusted the crossover and volume numerous times and the subwoofers are just extremely soft and quiet. I've also adjusted the volume control on my Innuous sense (volume down) and upped the volume on the i-amplifier with no effect at low volume listening.

Wondering what could be causing this, and how to potentially fix it? Would the amps volume attenuator have anything to do with it? Also before I was running my sub's of my power amp loop outputs, which I'm not using now. Then again the technics is rated at 150w@8ohm/300w@4ohm where my power amp was 200w@8ohm/350w@4ohm, so I figured I wouldn't need the power amps yet.

Speakers are JBL L100 Classic 75th Anniversary. And cables are RCA SVS subwoofer cables with a y-splitter off each R/L RCA cable to then you nnect in to both line level R/L ports on my subwoofers.

But dually concerning is that even when I crank up the volume on the subwoofer, they sound extremely tame and subdued.

Any help would be appreciated.

Thanks!
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Not much you can do with the sub turning off at low volumes, that is an internal factory setting. I’ve had subs that do that.
For best sub performance set your sub on the "in room" EQ setting and switch the 0-180 phase switch until you get the best volume. Turn your crossover to 80hz or more. That’s the only thing I can think of.
The other thing that comes to mind is that with the JBLs being fairly efficient, the subs just aren’t getting enough signal to stay up with the loudspeakers.
Scource content with no bass?
Take the sub out of the standby mode and put it in the on position. If you do that it will not shut off!
"...Take the sub out of the standby mode and put it in the on position. If you do that it will not shut off!..."

I looked at the manual for this sub, just an on off switch, I didn't see a standby mode switch. 
It could be the cable, or just to weak of a signal to keep the circuit excited.

I've had a couple of RCA through the years that took a dump and that is exactly how they acted. They would not tickle the Sub plate in standby and had a VERY low out put. Swapped out the RCA and fixed it right up.

Maybe when you swapped out, you damaged the plug or cable OR it's just not plugged in correctly.. check the splitters too..

Regards
"I looked at the manual for this sub, just an on off switch, I didn't see a standby mode switch."

Yep
Appreciate the advice, thank you.

I'm gonna...
1. Mess with the phase (0/180)
2. Try the volume attenuator setting at low level listening.
3. Try different RCA cables.
4. Try running them off my power amp.
5. Try high level connections off the SU-R1000.
But dually concerning is that even when I crank up the volume on the subwoofer, they sound extremely tame and subdued.
It sounds like the volume controls on the subs are set too low. This will help them sound less subdued and also stay on more.

BTW unless they are aligned well with your main speakers, keep the crossover point well below 80Hz. Otherwise they will attract attention to themselves.


If they seem anemic, try moving them closer to a wall. The room boundary effect will give you about a 3dB per octave boost. If you have them against the wall, for that reason they may become boomy. 
@atmasphere I have one sub in the exact same spot it was with my old system (didn't have this issue), also volume is cranked to max just to even hear anything from the sub.

What I'm doing different...

I am running a single RCA off the R out of the pre out of the amp to the right sub, and a single RCA off the L out of the pre out to the left sub. I have a Y splitter to then plug the single RCA into both my R/L line In inputs on the subwoofer.

Should I ditch the Y splitter (not use the line inputs) and just run the single RCA to each sub's LFE port, setting the crossover to "LFE" on the subs? I wanted stereo subs and thought LFE connections were for surround sound receivers with single RCA "sub out" ports and would not be stereo?

Someone suggested that using only a single side of the amp preout (R or L) sent to each sub might cut the power in half being fed to the sub, and might be causing the standby mode issues and low volume.

That a possibility?
You put a left and right signal into a left and right signal. Put the left into the left NOT the right too. You need to send the left and right signal to the plate, not a single wire and split it. The bass has a left, right (and center mix sometimes). 

Have you tried both left and right from the pre out to a single sub plate? If that works split the signal at the pre out and get a second L,R dual RCA. Use your splitters at the pre out and split the L,R. That is how I do it anyways.
LTE is different, a single cable in from a LTE signal can really make a difference. usually there is a 20-40hz bump (shelf) but you have to plug into the correct side and sometimes there is a switch.

Just thinkin'

Regards
@imhififan I did check the pre out being "on" in the settings, but haven't messed with the volume attenuation settings.

I'm getting sound, but just really quiet and underwhelming (not normal) compared to what I had before.
Have you tried different cables? I looked up your equipment thinking maybe it was an issue with bass management.  No bass management eliminates that possibility.  
I will be able troubleshoot this more tomorrow but I did try a single RCA to 1:2 Y cable to one of the subwoofers instead of the SVS cable and Y connector, but no difference.
Your subs are not getting enough level. The level they are getting is so low that unless you are playing loud it is below threshold and that is why they shut off. This is also why they don't play loud no matter what you do with the volume on the subs. When the input is too low no amount of turning it up will ever be enough. They only have so much gain. You can forget about cables and splitters and how they are wired, your problem is line level.  

You can check this with a meter across the RCA while playing music or a test tone. Line level should be around 1v to 3v. In your case it is probably a tenth or less of that.   

A big clue by the way, this all started with the new integrated. If you can't get enough signal from its pre-out the next move would be to run the subs off speaker level using speaker terminals on the amp. If the subs don't have speaker level input then you get a $20 Line Out Converter.   

That amp is plastered with doo dads and features. If you are really lucky you just need to change a setting to allow pre-out. Wouldn't that be something if that was all it was?  
Should I ditch the Y splitter (not use the line inputs) and just run the single RCA to each sub's LFE port, setting the crossover to "LFE" on the subs?
Yes. The splitter isn't helping.


But since there isn't enough output, I'd consider using the speaker level inputs instead.
So after just going to 1 RCA cable per sub with R and L pre out to line in connections it has seemed to help. I also switched the sub phase from 0° to 180° and that also has added some volume.

I'm gonna try speaker level connections, and I still need to try my bi-amped dual mono power amps, which also could solve this issue.
The phase control will add perceived volume at your listening position due to the subs working together and with your room/ mains better, but that has nothing to do with the signal levels the amplifiers inside them are seeing.  The line levels from your integrated to the subs are too low, like what millercarbon stated.  That signal needs to be increased to the subwoofers.
Yeah, gonna try my power amps and a different wiring set up over the next week.

Thanks for the advice everyone!
Just spoke to Kef customer support, they think its just low power signal in stereo configuration, but strange thing is they made reference to the Kef KC92 subwoofer and how it has line outs to daisy chain another subwoofer.

So I looked at the KC92 manual and it recommends LFE connections from the amplifier pre outs when attempting stereo connections of two subwoofers.

So...
RCA from R pre out to right sub LFE in
RCA from L pretty put to left sub LFE in

Gonna give that a try and see what happens.