Subwoofer advice


Sorry in advance for the long post but I thought it would be helpful to give as much context as possible in order to receive the most accurate advice.

I am new to this subwoofer thing. Currently I have a traditional stereo system. Dedicated amp/pre/dac and Harbeth 30.2 speakers. Now I am not unhappy with the bass output of the Harbeths, in fact, I was impressed with the useful output I heard under 50hz, even though they're only rated to 50hz.

I was thinking adding a powered sub or perhaps two subs would be beneficial as my Harbeths start to roll off around 40hz and I get no useful output below 30hz or so. I don't consider myself a bass head but I do like the occasional Daft Punk song, and know that a good sized woofer can make all the difference in a system. I think the Harbeth Radial driver is swell, but it struggles at higher spl, under 50hz. (Herb Reichart mentioned the logo will rattle against the enclosure with strong subbass, he wasn't joking)

I don't wish to add a processor into my chain for subwoofer management, even though I could (my preamp has home theatre bypass) I would rather do the "traditional" way where I set the crossover of the sub to maybe around 40hz and adjust placement in room manually by ear.

My room is small, 10x14.

My questions are thus: what brand should I look to get?

Should I get one or two subs? One to start?

What considerations must I factor in for seamless integration?
d2girls
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+1 for upgrading the speakers. That is the path to better sound quality without the complications of integrating subwoofers that will be slightly out of phase with your main speakers, despite all efforts. 
You can’t fix Harbeth bass with a subwoofer. It has a highish Q with resonance around 100 Hz from the woofer/cabinet and further port resonance at 50 Hz. This adds a permanent warmth to the bass much like a tube preamp. You really can’t get rid of it as it is a fundamental aspect of the design.

The bass will never be tight like you would hear on a low Q sealed box speaker playing Billie Jean.

I strongly suspect this is your problem- you have discovered a little weakness in the design (which is a strength viewed from another perspective). That said, the speaker is superb for jazz trio, pop and classic rock and any laid back female vocal piano stuff. Just don’t expect thumping disco or funk band or full orchestra to come out superbly articulate in the bass.

The best you could probably do is to gently roll off at around 110 Hz with a filter and hand over to a sealed JL style subwoofer at 90 Hz - this should give you an improvement in articulation.
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