Help! Subwoofer Newbie Problems!


Folks,

I’m new to subwoofers (having usually hated subwoofer set-ups almost anywhere I heard them).

However, I’m trying to downsize a bit from my Thiel 3.7s to the smaller 2.7s, and I’m trying out a couple JL Audio E-Sub e110 subwoofers with the 2.7s.

I have very little time to evaluate them before deciding to send back for a refund, so it’s a quick and dirty set up, just to see if I hear anything promising.

I’m using Conrad Johnson Premier 12 140W/side tube monoblocks, and the CJ Premier 16LS2 tube preamp.

I want to at least first try running the speakers full range and crossing the subs over at a lower crossover. So I’ve started by running speaker wire from the Thiel’s speaker terminals back to the subs high inputs. This is the way REL subs are usually set up IIRC.

First results (after dialing them in a bit), is that, yup, there’s subwoofers in the system. Lower lows. But it’s also really changed the sound. The good part is that the sound seems more spacious, rich and 3 dimensional. In that respect, they start competing with the larger 3.7s. However, there’s also obvious tonal change - the system now sounds a bit rolled off, darker, more full and lush in the mids, but also distinctly softer with transients being softened. It looses the energy factor.

I’m wondering what accounts for this tonal change. The subs are active, and so as I understand it, having them share the speaker terminals with my Thiels shouldn’t be drawing anything more from my CJ amps and making them work harder or anything. So...what gives?

To try and check this out, I’ve just received long RCA interconnects to try connecting the subs via my pre-amp outputs instead. This gets me into confused newbie territory.

My CJ Premier 16LS2 pre-amp has two sets of outputs. I have presumed that I just keep one outputs sending to my CJ amps as I normally do, and simply run the L/R signal of the second pair of outputs to the subwoofer RCA inputs (making one sub L and one sub R).

Problem is: I don’t seem to be getting any sound out of the subwoofer this way! If I use the speaker line high level inputs from my Thiel speaker terminals, I clearly get the subwoofers working. When I unplug those and send the line from my CJ pre-amps second outputs....nothing.

Any advice?
prof
gdnrbob,

Thanks.  Unfortunately I don't have flexibility with the choice of subwoofers.  My 2 channel speakers share the room with my home theater system, which is projection based.  I only have a limited area along the front screen wall to place a subwoofer, and they have to be as small as possible, otherwise they interfere with the projected image.  The JLs were the only high quality subs with the physical profile that fit my scenario.

The only other place I have for a sub is right behind the listening sofa, a few feet to the left of the listening position.  I'd be a bit wary of placing a sub there in terms of possibly localizing any of the sound.  Although I may try one of my two JL subs in that position, as placing two subs on a diagonal in a room is supposed to be a promising way of evening out room modes.

Little update:

I managed to get sound happening to the subs via my pre-amp outputs (turned out to be stupid user error.  I had to crank the output level of the subs far more than I imagined vs using the high level inputs).

Some listening yielded these results so far:  Dynamics didn't seem obviously restrained as with using the line level inputs.  However, there was still a real change to the tone, darkening (though also expanding of soundstage).   I love, love the tone of the Thiels and don't want that messed with.  I tried using only one sub and that seemed to split the difference - gave some of the recognizable Thiel tone back, plus some of the expansiveness of the sub.  Though back and forth between one sub and no sub had me thinking it was hard to decide which I liked.  The "best" tone seemed without a sub. 

So I'm still trying.  If I can get the good things I hear from adding the sub (added richness, bass depth, soundstaging) along with keeping the general character I love about the Thiels, that would be great.

Next step is to try the hook up most recommended for subwoofers: using a crossover to split the signal to mains and subs.  My JL Subs have a crossover, but because they are in a different room down the hall from my pre-amp/amp, that cabling is a nightmare.  I'll have to buy some additional 30 foot interconnects to test that out.

My plan has been, ultimately, to use a high quality analog outboard crossover.  Having spent a bundle recently on a great turntable (Transrotor Fat Bob) the last thing I feel like doing is digitizing everything with a digital crossover. 

Research showed that the crossover that fit my criteria best is JL Audio's CR-1.  It is very highly lauded for it's transparency and combination of flexibility and intuitive controls for seamlessly dialing in subwoofers with mains.   But...it's super expensive!  It would be over $5,000 Canadian.

As luck would have it, while working late last night I perused Audiogon and spotted a CR-1 that had literally just been listed that night....for $1,800!  The best price I've ever seen for a second hand CR-1.
I pressed "buy" as fast as my fingers would move and snatched it up.
Yay Audiogon!

So now I'm waiting on that to arrive.

If I feel I need to further tweak the subwoofers to the room, I'm not averse to the idea of only running the sub signal through some EQ/DSP.
To that end, I actually picked up a second hand Velodyne SMS subwoofer integrator.  A litte old in the tooth but may come in handy.
I've also been looking at the DSPeaker Anti-Node.

But...one step at a time.

 
I have a REL S5 and had a similar problem with my PSB T3'3s. It was my T3's tuning though and not the REL. My T3's have 3 ports in the rear and with all 3 ports open the Bass was deeper but looser,  and I lose a gorgeous mid-range. With bottom 2 ports covered,  Bass tightens up but doesn't extend quite as low,  and the mids and highs just bloom.  

Good luck because when you find the right mix having a great sub to lay that foundation for music and movies just right, makes for an unbelievable sense of space that brings you into the music or the movie into your room. 
Here are a couple other options to try with buy and return options being offered. A parasound halo preamp with hi pass and low pass output options so you can dial in the best hi pass option to the mains with your ears.  And or a crown xls drivecore amp with built in hi pass (many setting options) for your mains. If you try and like, then keep. If not, return. I'm pretty sure you will prefer the sound using a hi pass option. Also, if you haven't, sometimes just moving or angling the sub a few inches makes a big difference. 
I've had several subs and have quite a bit of experience with integrating them.  There is definitely something to the claim that having multiple sets of interconnects can mess up the sound.  It isn't always a problem but I've found that my benchmark dacs can't drive both the amplifier and a sub.  The bass quality is surprisingly degraded.  On the other hand, my Bryston pre can drive both amp and sub with no problem with no noticeable change in quality. 

I hate to say it but after having my systems in 5 different houses the best way to integrate a sub is to have your system in a large room in a house that has fairly lightweight construction.  I've had my system in multiple basements, smallish rooms in brick houses, medium rooms in frame houses, smallish plaster rooms in frame houses, and now in large rooms in a frame house.  I've also bought digital equalizers, made over 2 dozen bass traps and gone through extensive measurements with a measurement mic, real-time analyzer and various tone generators and discs. 

If I were you I'd buy the behringer ultra-curve and measurement mic (or something similar).  Get a tone generator.  This will let you do a direct comparison of the signal being fed to the system vs the actual volume that is present at the microphone.  If you do this it will give you a sense of proportion that I don't think you'll get any other way.  If you have a 12db peak at 60hz and a 12db null at 45 this will let you hear it and know what you're hearing.  You'll be able to completely squash the peak, although you'll probably be a little surprised at how deep of a cut you have to make to actually get rid of the bloat. 

Once you quantify what you're hearing you will be able to decide what you want to do about it.  You can make huge cuts to completely get rid of the peaks but in my opinion this won't sound right.  It seems to kill transients.  You can make a bunch of bass traps and that can help with the peaks without doing as much harm as huge eq cuts but it's either very expensive or a lot of work to get enough of them to really make a big difference.  In my experience it's impossible to completely fix a bad room, although the problems can definitely be reduced.  I haven't tried the processors that do processing in the time domain as well as frequency and I haven't tried making any sort of resonator.  I'd like to try it someday just to see how it works.  Sadly, I've got systems in really good rooms now and I don't have troublesome resonances that are bothering me.