Sub Pairing With Harbeth 40.3 XDs

i would agree with the sentiment that harbeths (specifically including the mon 40s) should be driven with a high grade powerful solid state amp, if the best bass response from the speaker is to be had

while not a particularly hard load to drive, the speakers are not very efficient @ 85 db/w/m and at mostly 6 ohms impedance (down to about 5 ohms in narrow band of midbass), most tube amps won’t control the bass driver too well, if asked to play at good volumes

...and others replying about subs with other (smaller) harbeths, well those are a totally different can o’ worms, so to speak - the op query is about using the 40’s - c7, super 5 and p3 owners are in a completely different universe of bass response...

How big is your room? SVS ported subs are pretty amazing for the price. If you want the concert feel, ported subs are for you.

All the best.

JD

I must agree - my 40.2's have all the bass (and more) than I'll ever want.  And... they simply must be driven and controlled by a high power SS amp, with a high damping factor (4000 for the H590).

My 30.1's also sound superb with the H590.  

They almost have too much bass - but, that's probably the room / placement.

I'm running two JBL 2269H 18 inch drivers in two custom cabinets that are based on the JBL SUB18 cabinet.  My sub cabinets are passive, ported cabinets.  Crossover is a McIntosh MEN220 and the 18's are driven by a McIntosh MC500.  I have a concert level kick drum feel in my living room if I want it and the subs will completely integrate and "disappear" for all the rest of my critical listening.  Nothing like JBL low end...but it must be set up right.  Crossover point and slope is critical to good integration.

I highly recommend 2 subwoofers.  This has improved my system immeasurably.  I had big problems with base at 60 and 120 hz. due to room sizes. I use 2 Definitive Technology super cubes 4000. I have tried KEF, SVS and Sony but can hear nil difference. Using 2 smaller subs helps with speed and balance, I also use a Minidsp, whilst I resisted for years this has been a revelation. Removing the bass to my main speakers below 70 Hz has improved their dynamics and pace, I cut the room node frequencies by 6dB and roll off the bass starting at 40dB.  You can also try altering the phase of 1 or both subwoofers.