At present using a chrome 250 to drive some obelisks with some success.
I do feel that the high frequency output is low from the mid range/tweeters.
I have read that the regulator boards are an issue with a 250 in regard of the low impedance in the high frequency range of the obelisks.
The olive 180 without the regulator boards may be a solution.
Having looked at the specifications of the DR250 it does mention they can drive 2ohm loads.
Am I right in assuming the old 250 amps do not have this capability?
IIRC, the old NAP250 was something of a minimum requirement for driving Obs. If it’s getting on a bit and not been serviced within the last decade, all bets are off.
The NAP135s were reputed to be much better with Obelisks. The extra (fan) cooling probably helps, so consider the 135s or maybe even a s/h NAP300.
You might even find an unregulated amp like the 180 copes better with them, as the amp will be allowed to sag when things get tough, something the 250 isn’t allowed to do, so if things get too tough it just shuts down.
Apologies Analog, I wish I could explain better, but I’m not an engineer and so layman terms come easier to me. basically, it’s down to the 250 being a regulated amp.
Ob’s and Naim amps can be somewhat frustrating. Probably my most successful pairing was with either a 282/SC2/300 or, believe it or not, a Nait 5i. With my last pair of Ob’s i ran a few combinations to see what worked best, which included a 42.5/110, a 42.5/160, and 42.5/Hicap/160, all serviced, and a Nait5i. As my 160 had been sounding so good through my SL2, i fully expected it to sound good with the Obelisk, but instead it sounded awful, absolutely awful in fact, as though i’d thrown a blanket over the tops of the speakers. The 42.5 with the 110 sounded vastly better, much more lively and at least listenable. The big surprise however was with the Nait5i, simply a joy, albeit until the volume went too high and things got a little out of control, but it played more than loud enough for most people.
Presently i use Compass with an original Nait5/Flatcap2, which makes a very good account of itself indeed. I think it a far better amp than a Nait 5i, with or without the Flatcap. I have run both a 32/Hi/110 and 72/180 through the Compass too, all of which do a very fine job, but Compass present nothing of the load that the Ob’s do, and in the long term, the Compass suit my room better too. I’d love to re visit the Ob’s with my 72/180 or 110, just to see if i get the same result, but my time with Ob’s was a little frustrating, and i’m not sure Naim are best suited.
I ran Obelisks for several years with Naim amps, starting with a 250. Then a pair of 135s, and finally a 500. They’re a bit of a problem to drive hard as they drop to 1 ohm resistance at points, they sounded great whichever amp I used, but obviously benefited from the extra oomph of the 500.
Sadly, after many years, I longed for the sort of bass that I wanted…and that was, for me, only found in wacking great transmission liners.
Thanks all for your experiences, may not the best suited to Naim.
After reading some reviews about the output comparing the dr250 to the earlier amp the wattage has increased over the different impedances.
For 2 & 1 ohm respectfully the dr outputs
265 & 345 watts
The original 250 was140 & 62 watts
I realise it is not as straightforward as increasing the power will make things better.
On the upside some cds that sounded awful before are now sounding a lot better
System is cdx/Xps 82/supercap