What type of Amp for Ohm Walsh F-5015s?


AudigoN Team,

Looking for some thoughts on amplifier choice for Ohm Acoustic F-5015 speakers that I will be getting shortly.  Would these sound better with a class D amp or a class AB amp? 

I have some space restrictions (17 inch deep open wood shelving with a back wall) that are limiting my amp choices absent a furniture change and I don't want to do that unless totally "painted into a corner"  John, the owner of Ohm told me that I should have at least 200 watts at 6 ohms to power the F-5015s.  The powered subwoofers built into these speakers come with class D IcePower amps with line level inputs, so the amp that I obtain must have two line level subwoofer outputs.

The two units (2 line level subwoofer outputs, 200 watts around 6 ohms, less than 17 inches deep, don't run hot) that have come up in discussion with John and Evan at Ohm are the class D NAD M32 and the class AB Parasound Halo INT6.  I have read that the INT6 doesn't run too hot, so it hopefully would be ok in a piece of wood furniture.  After my discussion with Ohm, I saw that the class D Peachtree Nova 500 could possibly work based on the specifications, but can't seem to find any reviews on this higher power Peachtree amp.  Another wild-card that would be much more expensive and offer higher power output would be the NAD M12/M22 v2 combo.  I am aware that you likely get what you pay for and that the NAD systems are higher priced, especially the non-integrated combo.

Would appreciate your thoughts / amplifier guidance and any additional suggestions.
michiganbuckeye
@mapman  I have often thought that a tube pre-amp with a Class D amp might make a lot of sense.  Conceptually it makes a lot of sense to me as opposed to a tube pre-amp with a tube-amp.. that always makes me wonder what flavor are you getting from the tubes?  Plus I like bass, but I want it relatively tight.  

@michiganbuckeye I would consider the 5000's neutral.  Keep in mind the adjustments on the back do make a difference.  For instance with my pass labs preamp and amp, I prefer the mids and treble in the (+) position (mid-bass and bass are left neutral).  For a while I had a mark levinson integrated amp I was trying.  It was clearly a brighter presentation than the Pass, I ended up turning the treble with it to the neutral position.  

I also happen to be in Michigan.  Drop me a PM if you are interested in a listen.

With separates, just keep in mind that every combo of amp and pre-amp will sound different as well. Tube or no tube.

The key attribute normally for the amp with at least any fully passive Ohms for best performance is high current delivery and damping factor. Class D amps or large bulky, heavy Class a or class a/b amps tend to fit that bill. Tube power amps need not apply IMHO unless one wants to relegate much of the bass to a separate subwoofer, which is uniquely inherent though in @michiganbuckeye's  case with the F5015 model specifically.

I find tube amps or even SS amps that emulate tube amps with higher output impedance/damping factor are not ideal. The larger the OHM Walsh driver the less ideal in that bass will be fatter and less refined and articulate and that also tends to mask mid-range detail.

That’s not to say some might very much like the resulting sound, even if things are not all as optimized from a technical perspective.

In general, I find the tube pre-amp/Class D amp combo done well can be very cost effective and deliver that articulate bass as well as all the rest and makes for a sound that one can just sit and enjoy for hours on end.

Again, with the f5015, teh built in Class D amps will in fact handle the bass, so you can likely use most any amp SS or tube to good effect as long as the setup provides the dual line level outputs for sub. Having an active crossover on-board the amp to be able to refine the sub crossover characteristics as needed sounds like a huge advantage as well, which I suspect is why JS recommended those particular amps.


@michiganbuckeye

One qualification on my above post needed for teh f5015 case specifically is that I believe the f5015 has no subwoofer crossover controls on board in which case the crossover has to be done upstream somewhere and those particular amps JS recommended appear to in fact have the sub crossover adjustments and dual sub specific outputs (not just any line level) needed.

I heard the f5015s at capital Audiofest last year. John Strohbeen had them running off an Outlaw receiver somehow with some outboard device providing the needed crossover apparently. I would assume that Outlaw receiver had dual line level pre-amp outputs that fed an outboard pro audio type sub crossover unit of some sort....don’t recall the details. JS could probably tell you more if needed.

That type of setup using a separate subwoofer crossover unit with dual rca line level inputs and dual sub rca line level sub outputs would add some complexity but open up more amp possibilities, including pre-amps with a spare rca connector type line level output (the main pre-amp out would go to the power amp).   For example the AudioResearch sp16 tube preamp I use has that and I use it to run a sub with a pair of KEf ls50s.  

With an outboard crossover, one amp that comes to mind I have heard and really liked is the tube/Class D hybrid Rogue Pharoah.   I think that has a "processor" line level output that could feed an external sub crossover.

Again, I would not make any big investment without running it by Ohm first just to make sure things can integrate properly.

Whatever amp you choose, those speakers should be the absolute bomb!