[bbslo]

I'm using an old-school subwoofer (Advent from '96) and passive pre-amp (Mod Squad Line Drive). I had it hooked up high level which seemed to work fine, but wanted to hook it up low level line in with RCAs. The subwoofer has no volume control -- only two continuously variable crossover controls (marked 40-80 and 120-180). I found when I hooked it up low level that the subwoofer output was almost nonexistent. It seemed like it needed a volume control, but doesn't have one. I assume this due to the passive pre-amp. Is there any fix other than a non-passive pre-amp or going back to high level?

[srb]

Having two crossover frequency controls doesn't make a whole lot of sense.

If this is the subwoofer - the control on the left is Level (volume) and the one on the right is Crossover Frequency (with markings at 40Hz, 80Hz, 120Hz, 180Hz).

If that's not the case, and you truly have no level/volume control (or it's non-functioning), the the passive preamp is certainly part of the problem with very low output.

Steve

 

[bbslo]

Thanks for the reply, Steve. Wow -- that was pretty dumb of me to not look more closely. Of course you are correct -- it does have a volume and single variable crossover.

Regardless, it sounds like low level with a passive pre-amp (at least this one) just isn't going to work. I picked up this subwoofer to try out using a subwoofer and I do like it (adding a subwoofer to fill in the low octaves with bookshelves) and now want to consider investing in a nice, musical subwoofer. I guess my options are get an active pre-amp or use the high level inputs. I suppose if I had a higher quality sub I wouldn't be as concerned with some loss of quality by using the high level inputs.

[srb]

If a passive preamp works well in your system with your sources and amplifier, you may want to consider one of the REL subwoofers.

The RELs have a very high input impedance with a specially designed input circuit so that their high-level input with SpeakON connector is actually the recommended and preferred hookup method for an REL.

The line-level input is provided merely as a convenience for an HT processor or for systems with Class D amplifiers that don't use a common speaker ground and should not be connected to the high-level speaker input.

Steve

[Letitroll98]

I dunno, I've run several subwoofers off two different passive pre amps and never had a problem.  Maybe it's the sub.  Have you tried, or can you try, a different sub?

[bbslo]

I've heard good things about the RELs and they are on my radar, but probably out of my price range. Maybe used though.

I don't have another sub to try, but I did try this sub hooked up high level and it sounded pretty good. Just wasn't wanting to hook up the sub that way.

I do know that with this passive pre-amp I turn the volume about half way for fairly loud listening, but when I had an active pre-amp hooked up to the same amp, I could only turn the volume up a tiny bit before it was very loud -- one of the reasons I like the passive pre-amp.

[Russell Dawkins]

The Elac S10EQ is also an interesting alternative, if $500 is within your budget. It has a clever wireless auto EQ adjust feature using a smartphone as the microphone.
https://www.youtube.com/watch?v=-WeOCdk23Dk

[Letitroll98]

What I'm saying is that if the source feeding the passive pre is enough to drive your main amp from the line level, then it should also drive the line level inputs on the sub, unless something is amiss.  Your not talking about the sub, it's the amplifier in the sub woofer, which should behave very similar to your main amp.

[bbslo]

Possibly. It seems to work fine connected high level so in that sense the sub's amp is working fine.

[RDavidson]

You might consider a buffer between pre and sub.
Passive preamps can work well in many cases, but sending a signal through long IC's is not one of their strengths. A buffer would provide more voltage to reach the sub.

[bbslo]

I think the solution for me will be go to a more musical higher end sub. I'm happy with my speakers 95% of the time, but there are a few songs that I listen to with this sub that clearly benefit from it. But I think for other music this little ported sub just isn't keeping up with the rest of the system. I think it would be a fantastic inexpensive sub for movies and maybe if you just enjoying some thumping bass in your music. I'm thinking I'll be better off with a higher quality sealed sub for my music only use.