I recently purchased a sub 37-- it sound great. I also bought a 12 inch ELX112P active loudspeaker for it. I am noticing an audible vibration on a number of notes. Just wondering what your take on this speaker is because I can return it and get a new one or I could get something else.
What speaker in the 5-600 dollar range do you guys recommend for synths if not this one? I would just be practicing on it and doing small coffee shop size gigs playing the bass role.
Thanks
Roland KC 550
+1 on the KC-550 sounding the best. SO big tho. 
If you can get your hands on a used Motion Sound amp, they sound incredible.
One in your price range showed up in a quick search. Here’s the link:
Last year I upgraded my studio powered monitors to a pair of JBL LSR308’s prior to arrival of my Sub 37 July, 2014 and must say you get a really fine monitor well-within your stated budget and they are not exaggerated bass or anything else, they simply just sound great, clear at all volume levels and both my Sub 37 and DSI Poly Evolver do not even make the monitors break a sweat. Built solid. I tested many monitors and these even out-performed monitors costing almost twice as much. 
They are currently on sale at Sweetwater for buy one and get second one half off and that is how I procured mine last year
http://www.sweetwater.com/store/detail/LSR308
I am sure they are great as studio monitors but you won’t be able to gig with them. The OP wanted something for home and small gigs.
Something that handles deep bass with maybe a horn. I use a compact ampeg 220 watt bass amp w a 15 woofer and horn and it handles it all no problem. Or a keyboard combo probably does more mids/highs also.
I use my 70s Dynacord Leslie with a 15’’ woofer. You have inputs without the rotating horn and can reserve this for your organ - like I do with my Nord Stage.
This beast is LOUD and clean, just perfect. You can get it for around 100 bucks (at least here in Germany).
can you give us more info on how you get the audible vibration to happen? I run my S37 through 5 year old JBL 512 powered speakers and never get a ratlle or hum (pun intended).
I’m thinking it’s more of a defective speaker issue than an overall issue with the ELX112P, those are decent speakers.
Sure, they may be a bit on heavy side but they work perfectly sonically for small performances as well.
Get a bass amplifier. Good ones are full range, and aren’t as muddy as the Roland 550. The only thing with a bass amp is you’ll need a mixer, but if you have more than one keyboard you should have a mixer anyways. I bought an inexpensive one that goes in a rack with my amp.
I used a MarkBass head with a Traveler12H cab. Plays high, plays low and sounds great.
Now I use a boutique company out of Idaho, Vivid Amps. Really light cabs and heads.
I had once the TCE RH450 head with RS210 cabinet to play quite normally bass through it. Beautiful Boutique gear, with a lot of nice features and design. Sadly, I had to sell these, so can’t comment about Sub37 through it, but man that combo sent a wall of sound it was frightening, and certainly when you see the size. To help things out, one can also chain a second RS210 and add an RS112 if something is lacking in the low end 
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Mine goes to KRK roket 5’s but NEEDS the KRK subwoofer to let the neighborhood know I have a Sub37 
I don’t think studio monitors are gig worthy. The cones and tweeter typically have absolutely no protection from damage whatsoever. They are typically installed somewhere and never move after that.
The rattle went away… I think it was the cage over the front of the speaker and it was only on certain notes. Anyway it went away and I’m keeping it. I think the sound is really good.
I got the KRK6 cause i read the woof was down the basement… I can’t tell if it’s colored or not (without a reference and someone to explain what i’ve read about sound color) but the krk6 is without going 50% full already overkill and the bass (coming out of the sub or the AR) are absolutely veloptous…
Serious overkill for my studio but you get that bass and it shows on other speakers… Took me a while to find that kind of calibration… what i hear is what i will hear elsewhere (except that bass)…
I encountered the same voyage, and what started out as $5-600 budget, got frenzied, gassed, rationalized and up-sold into a QSC K12, that eventually became a complete pa system 2 years later, with a QSC sub. It was a complete impulse buy, but It has ended up being one of the best gear investments I have made. I practice with a bass player and drummer, we throw both my sub phatty, sub 37, roland e-kit, live mics, reason (with massive filter sweeping effects, drones, pads, delays, etc…), guitar running through pedal board, and sampler, all with live bass and drums…It handles seamlessly with ample headroom, and gives me confidence for any live use (monitor or front).
The first few posts had it. Roland KC-550. Big, heavy, loud, and rich in low end.
+1 on the K12. I have a pair and they definitely deliver the goods! Not cheap, but well worth it if you’ve got the cash. Other than cost, the only downside is the weight (42 lbs each).
QSC k12
PS. We just upgraded the PA to the Bose F1 system so I have two used K12’s for sale.