Low sub out volume from receiver

[lincolnvi]

I just purchased a Teac receiver model AG-H380. At the moment it is driving 2 Kohler SoundTile speakers in my shower. I wanted to add an in wall subwoofer out in the dry bathroom area. I bought and installed an OSD IWS-10 and an Audio Source AMP-100 to bridge and power the sub. The Teac receiver has a sub out RCA jack. I hooked this to the AMP-100 using a single connection to the RCA input the manual said to use for bridged mode. I have to crank the sub amp volume all the way up to get very minimal bass, the amount of bass I would expect with the volume at maybe 10-20%. It does get slightly louder when you turn up the receiver volume, but still extremely low. I purchased a TCC TC-780LC line level amp to up the voltage to around 2. I got it installed and it did improve the volume level, but now it has the same bass at 3/4 volume as it did at full volume before the line amp.

Did try hooking a RCA to the sub amp input and to my phone with a headphone jack, and the sub puts out great volume at only maybe 30-40% volume on the dial. Called Teac and they had no idea what voltage the sub out produced, so they were no help other than offering to replace the receiver. There are no adjustments on the receiver other than bass and treble, within the menu.

Does anyone think that a better line level amp, maybe boosting to 3 volts or so, would help me? The AMP-100 has no speaker level input. Could I get a speaker level to line level adapter and piggyback the speaker out wires on the receiver then to the RCA in on the sub amp?

Any help is appreciated.

 

[americanaudiophile]

It may be that the sub out of the Teac is crossed over too low for the sub to actually put out much. Or as you say it may not be pitting out enough. I would use a speaker to line level adapter to feed the amplifier. That should give you plenty of output and be cheaper than an a line level preamp. You will also be feeding it a full range signal as you did with your phone. The performance of an in wall sub is greatly affected by the wall and position it is mounted so a full range output will give you much more music to feed it.

 

[lincolnvi]

It may be that the sub out of the Teac is crossed over too low for the sub to actually put out much. Or as you say it may not be pitting out enough. I would use a speaker to line level adapter to feed the amplifier. That should give you plenty of output and be cheaper than an a line level preamp. You will also be feeding it a full range signal as you did with your phone. The performance of an in wall sub is greatly affected by the wall and position it is mounted so a full range output will give you much more music to feed it.

Thank you americanaudiophile for your reply.
I don't think the crossover is too low, as I did hear a little midrange in the sub. I did install a FMOD 100hz low pass to get rid of the mid.
I got a speaker level to line level adapter, but I am afraid to use a Y cable to combine the L/R channels to a mono in for the sub. I read several places that this can damage the receiver. I don't want to use just one channel as I want the bass information from both channels.
I would really like to use the sub for just the lower frequencies, so I would like it to work as it should using the receiver's sub out connection.
What I really would like is a line level amp that would put out around 3 volts. I found several ones that go up to 3 and beyond, but they all seem to require 12v DC, for car stereos.
Does anyone know of a home line amp with a higher output.