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

Showing 10 responses by prof

yogiboy,

The ICs are new, just arrived.  I doubt both new cables would just happen to be broken.

jzzmusician, I triple checked they were in the right input.

adsell, no slave mode on these subs.  Crossover set around 30 Hz.
No mention of reference or variable switch in instructions or on sub.
Not using phase switch.
Thanks.

Any diagnosis on why the sound changed via speaker line levels or why I wouldn't be getting sound from the subs when hooked up from the second preamp outs?
Yeah, I better check that my CJ is actually putting out sound from both sets of main outputs.

The preamp SHOULD be putting out signal from both outputs simultaneously, shouldn't it, so both outputs can be used at the same time?  (I don't see why there would be two sets of outputs otherwise).

I have swapped the outputs and verifed both sets of main outputs on the CJ preamp are working.  I also tried L signal from one set of outputs and R signal from the other, to verify the amp sends a signal to both outputs at the same time.

I'm therefore baffled as to why I'm not getting subwoofer levels when I send to the JL subs!
I only have one more day with these things so I have to figure this out fast.

The subs worked when I took a line off the speaker terminals to the high level speaker input of the subs.

But in the following set up, I'm still not getting sound:  Speakers still run full range.  Subwoofers getting the signal from my pre-amps second outputs to the subwoofers unbalanced RCA inputs.

And...that should be it, right?  The subs should be making sound and I the crossover setting, which I haven't changed, should be rolling them off so they blend with the speakers.

Am I missing anything?
yogiboy,

Unfortunately this is the last day I have to evaluate the subs before the return policy expires.  So that's why I've been frantic to try and diagnose these problems.  JL Audio won't be open today.
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.

 
Great responses, thanks!

snapsc,

I like my Conrad Johnson tube preamp/amp too much to switch to solid state.  Every time I've tried SS I've run back to tubes.  Learned my lesson.  (I believe the crossover I'm going to use will pass along the character of my pre-amp ok).

Jon,

Your experienced input is valuable.

The ability of my CJ preamp to drive the signal over long runs of interconnect are a bit questionable.  That's one way adding the JL CR-1 crossover helps, which will drive things no problem.

My listening room was designed with the help of a acoustician, so it has treatment, trapping, sort of "built in."  It's a great sounding room (and a wide opening to one side into the hall seems to stop a lot of bass room-node wave build up - the big Thiel 3.7s for instance sound perfectly even in the room).  I won't be adding any more room treatments.

I've considered going with a good mic and computer software to read the room, but I'm trying to make this as user friendly as possible.  So I'd first probably go to items like my Velodyne SMS or an Anti-Node, to dsp the subwoofers.

I'm still curious if subwoofers can actually be added in a way that doesn't alter the general tonal character of the main speakers.  After all, adding frequencies anywhere does tend to have a psycho-acoustical effect in how we perceive the sound.   As mentioned, my bigger Thiel 3.7s go lower than the 2.7s, and preserve the Thiel sonic character I'm looking for.  Except they are aesthetically larger than I want in the room.



Good info about the anti-mode, willemj.

I've heard that it's not quite transparent enough for some people when used over the entire system, but works well on just the sub signal.  Sounds like that set up worked for you.