Axiom Home Page Forums General Discussion Stereo New to subwoofers

I received my m2i on Monday and I'm extremely happy with my purchase. I bought a slightly used KEF PSW 2000 sub. I've been trying different positions for the sub and I guess that I'm pretty happy with the over all sound. KEF claims this sub will go down to 35. My question is my crossover control goes from 80hz to 120hz. The mti's go down to 60hz.
If I keep the the setting at 80hz, does this mean that my mti don't get anything below 80hz??? If yes should I
get a sub with a lower crossover setting?

Thanks for your time,

John

John, you didn't fully describe your setup and it isn't clear whether the 80-120hz crossover is on your receiver or the sub. In general, the sub should be placed right in the corner closest to the M2s. The M2s should be set"small" on the receiver and if the receiver crossover is adjustable it should be set at 80hz. This rolls off the bass below 80hz to the M2s and sends it to the sub instead. Since the receiver is handling the crossover, the one on the sub is unnecessary and should be bypassed, if that's available, or if not, set to the highest crossover setting on the sub so as to get it as far out of the way as possible.

Sorry I wasn't specific ..... The crossover is on the sub. This system is for music only, Amp, pre amp and cd player.
I have the m2i's on stands about 4 1/2 feet apart and the sub is in the far right hand corner about 3 1/2 feet behind the m2i's. The controls on the sub are Crossover 80hzto 120hz, phase adjust and input level.

Okay, John, things are becoming clearer. I assume that your pre-amp is designed just for stereo operation and doesn't have any internal crossover for a sub output. In that case regular speaker wire is used to connect the speaker terminals on the amp to the high-level speaker input terminals on the sub. The M2s can be connected with speaker wire directly to the same amp terminals connected to the sub, or ,if the sub has speaker level outputs for the main speakers, they can be used instead. If the sub outputs have a crossover to the mains for this second type of connection it should be described in your sub owner's manual. This would help to decide which type of connection to the M2s to use.

The 80hz lowest setting which you say the sub has is unusually high and you'd want to leave it at that lowest setting(assuming that it's relatively accurate; many aren't). The M2s would then be getting a full-range signal(unless the sub has a crossover on its output to them), but would be rolling off quite steeply below about 80hz on their own as the NRC measurements with the SoundStage review show. So, the 80hz sub crossover should blend fairly well with the natural M2 rolloff.

The sub location seems good, but the M2 separation seems a bit narrow. The rule of thumb is to separate them about the same distance as your distance from them.

Yes my amp is a solid state (Amber series 70 "1983"), 70 watts a channel. I have compared it to quite a few of the new amps on the market and it holds it own quite well, so well infact I've yet to find anything to replace it. My preamp is a (Superphon Cd Maxx "1989") line amp and again it holds up very well. Needless to say my amp doesn't have a subwoofer output. You are correct in the way I have it hooked up. I go from my amp(speaker wire) to the left and right inputs, then I run speaker wire from the left and right outs to the m2i's

Specs for the Sub are as follows:

Type..........................powered subwoofer
LF Drive Unit.................1x210mm (8in.)
Frequency range...............35Hz - 150Hz
Amplifier.....................150 watts built in
Max output (SPL)..............106 dB
Low Level Signal Inputs.......RCA phono sockets
High Level Signal Inputs......Binding posts
Low Level Signal Outputs......RCA phono sockets(Actively filtered at 12dB/octave 70-170Hz)
High Level Signal Outputs.....Binding posts(Actively filtered at 6dB/octave @130Hz
Enclosure Type................Bass Reflex (Twin ports)
Internal Volume...............15.4 litres

Thank You for all your great info.........

John

Bingo. "Actively filtered at 6/db octave @ 130hz". If by "left and right outs" to your M2s, you meant the outs on the sub rather than the regular speaker terminals on the amp, I don't think that's the best way. As I mentioned in my previous reply as a possibility, the sub does in fact have a crossover(filter) on its speaker level outputs to the mains, but it's too high(130hz)for best results with the M2s. The slope is mild enough(6 db/octave)that this isn't terrible, but the M2 can do a pretty good job down to about 80hz and I'd think that the 130hz sub filter should be avoided by using the first type of connection to the M2s described in my previous reply,i.e. run the speaker wires to the M2s directly from the same amp terminals where the wires to the sub are now. This sends a full-range signal to the M2s with their natural rolloff below about 80hz blending with the sub rolloff above 80hz. If you keep what I understand is your present connection, the sub crossover should be set at 120hz rather than 80hz, so as to blend better with the 130hz crossover to the M2s and lessen the partial gap that would exist between 80hz and 130hz. I suspect that the 80hz/80hz arrangement would sound a bit better, but experiment.

Yes the outs on the sub rather than the regular speaker terminals on the amp! So by having
it hooked up this way (the outs coming out of the sub to the m2i's) I'm not really utilizing the
full capabilities of the M2i!?

Ok.....I'll hook it up the way you suggested in the AM. So let me get this straight, I run a set
of speaker wires from my amp to to the sub, and then run another set from the same amp
speaker terminals to the m2i. With this set up should I keep the frequency set at 80 Hz? Is
this right? (It's late and I'm fading fast)

John

Yes, both sets of speaker wires would be hooked around the same speaker terminals on the amp. This causes no problem; the input impedance of the sub amplifier is so high(10,000 ohms or more)that essentially zero power goes to the sub, just the musical information. Yes, keep the sub crossover at 80hz.

John,

I set up my sub as you suggested .... noticeable improvement! Thanks a million...

John