The sub should be fed from the preamp (not the amp), thus eliminating any sonic signature from the amp (which would probably be minimal).
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I have a sonic fontiers line 1 and sonic frontiers sfs-80 amp. I added a Paradigm servo 15 with the x30 xover. The mid's and hi's I notice had less detail since the addition. Is this because the xover is SS and in between the tube pre and power amps? I have now disconnected the sub and thinking of trying a Y connector at the pre amp, one end feeding the power amp,other end to the xover and set the cut off to the sub at 35-40Hz.(main's response is at that region). Has anyone tried this with success?
Hi Leeph. the paradigm servo 15 is a very good sub, however the x-30 crossover is rather mediocre at best and in my opinion defeats the purpose.I believe the sf-1 has 2 pairs of outputs. You can run 1 pair to your amp for the main speakers and use them full range[no crossover] and the other pair to the x-30 and "try" to blend in the response of the sub with the gain on the servo amp.This approach is a rather labor intensive proceedure as the location of the sub in the room is now much more critical as far as making the mid and lower bass sound cohesive with the mains.The adjustment of the phase pot on the x-30 is a very big plus for this excercise.You did not mention the main speakers you are using but adding a little foundation or bass weight can be an exercise in frustration.I personally would dump the x-30 and buy a better crossover.There was an audio research e-21 listed here on the GON recently at $400.[great price and great crossover]! the audio research crossover is a purely passive crossover for the mains and active for the sub.It employs 3 12ax7's and the turnover frequencies can be changed with capacitor kits from audio-research. The bryston 10b is another very good crossover that does not add much of a "signature" to the main speakers and is light years better than the x-30.Once in a while you will see an old dalquist[can't remember the model #] crossover surface periodically... this is a also a purely passive crossover for the mains and really is a great crossover if functioning to spec.
I have owned the servo 15/x-30 combo for a number of years and discovered that the active crossover does take something out of the high pass signal. It is an excellent sub crossover but leaves something to be desired for the highs.
Ecclectique hit it right on the head with using one set of outputs for the mains, and the 2nd set for the x-30/servo 15.
If not two outputs then the tape monitor output will work. This is what I am personally doing at the moment with good results. The x-30 with its infinite phase adjustment, crossover point, and gain control makes it very easy to blend the sub into a room (provided you dont stick it in a corner, avoid the common fractional cancellation points, etc).
Nrenter, I too have been using an X-30 with a Bryston 4B amp and NHT SW3P passive sub and I'm quite happy with this arrangement. I have not tried the high pass section of the X-30, and as I suspected from the other posts here that it compromises the performance of the main speakers being used with it.
I'd like to add a caviet to my previous endorsement of running a tube amp for your mains with a solid state powered subwoofer. I've found that the while a subwoofer can improve the overall bass, the quality of the bass you get from your main amp and main speakers will also have a great influence and/or limit the overall quality of bass you get even with a sub. I've noticed this even among varying solid state amps.
Ecclectique,thanks for the suggestion. After disconnecting the xover from the pre-amp I realized there is 2 outputs! And thats how I connected my system. My mains are Tannoy Rectangular GRF with 15" golds. After a bit of tweaking with the xover, I've notice a great improvement. I will upgrade my amp (ie. SET amp) before I get a better xover,but that will be a while.