I’ve done exactly that. It’s not a sideway move. The 202/200DR is better than SN1 in every aspect.
It is more important to have amp and speaker matched perfectly. There are 1 watt valve amps that can power huge speakers and I’ve heard a home made 8 watt valve amp drive large horn speakers with ease.
2 Likes
Hi Zen,
The Krells were pretty impressive. Several magazines tested the KSA 50 and found it did indeed do the doubling of power each time down to 1 ohm. I can’t say if this was true for the KSA 80 that bailyhill owns, but the KSA 100 and the KMA 100 did this too, so an amazing 800w into 1 ohm. I used to use either the KSA 50 or KSA 100 to drive the Apogee Duettas in the showroom, and they did pretty good. We never got to stock Scintillas but the talk at the time was they were equally as difficult to drive.
I suppose it always gets down to the VA rating of the power amp, and the stability into ultra low impedance loads. The ML-2s I spoke of earlier had I think 7A on tap even down to 1 ohm, don’t know what the Krells measure at, (not many reviews do this), but I suspect they were, as the boys at Rolls Royce say, “adequate”.
I never could get myself to plonk down the cash for a Krell, although I got close. Loved the weight and control but ultimately missed the “groove” factor. I listened to a second hand circa 2005 50w (?, can’t recall the model) Krell integrated a few years back, against my 172/200. This more modern amp had pretty good “groove” and great control, but then again, Naim have upped their game considerably too. So yes the Krell was a pretty good unit but again I stuck with my Naim combo.
1 Like
Non DR500’s are half that price … I bought one…and even though it was 15/16yrs old it sounded fantastic. A Krell of a similar age would probably be pretty crispy…
May I ask for more details in that change even though I of course understand all the parameters and that it cannot be translated to me and my setup 
Thanks for this post … so interesting…those 1st few watts and the energy store behind them are so so important…
1 Like
Waiting for someone to say that.
1 Like
It is interesting how power supplies affect the sound. We are all aware of Naim’s commitment to this path. But in the early days it wasn’t always so obvious.
I had had a discussion with JV about the importance of the regulated power supply in the NAP 250, and how much of the jump from the NAP 160 in sound quality was down to this, rather than the lift in output.
But when the HiCap lobbed into our demo room, there wasn’t much talk about the reasons why this crazy new product was important. I remember being flabbergasted upon upgrading a SNAPS to a HiCap, using a 32.5/250 Isobarik system. To be honest, when I did the demo I wasn’t expecting much, and was thinking my client, (for whom I was doing the demo), would probably pass on the upgrade. How wrong I was.
I could expound at length on the importance of a really stiff regulated power supply for the power amp, and back in the dim dark past, Naim weren’t the only guys pushing this. You could get wrapped up in transient power, difficult impedance curves, damping factors et al. But we all knew that pre amps just needed a quiet, clean power supply. Maybe 500 to 1000 mA at 12 volts, and hey, we’re all good.
Now floating the idea of a PS555 at $15k to run your little streamer, (or why not go two of the blighters if you have the dosh), seems mainstream. Well Naimstream at least.
Ofcourse. However it’s difficult to explain the sound differences. Maybe cleaner, faster, tighter, bigger, more musical. In short I want to listen to music all the time, which was not the case with the Supernait. Bare in mind though that a lot of changes has been done since the move from Supernait to 202/200DR so it’s a bit unfair to make all those claims regarding the change of amplifier. If and only if I remember correctly, the first impressions were overall cleaner and more powerful through 202 compared to Supernait. Both were driven by a Hicap.
Come to think of it, that’s probably what I got wrong… and why I was so cr*p at designing preamps, despite being able to get poweramps right!
Hey, at least you can design a pre amp. Best I got to was speakers! Although my cast concrete boxes showed some promise, and my Corian enclosures looked awesome, the sound of my efforts generally missed the mark. By a long shot. My friend got pretty good at speaker stands though.
.
Hello feeling_zen
In general, you are correct. However, that was one of the hallmarks of the Krell Amps, and this one in particular. They double in power for each halving of the impedance. I think is has to do with the ability of the power supply to deliver the current necessary. This amp had an option from the factory that they did to make sure that one ohm loads were ok. I checked the owners manual and confirmed this.
This does not accord with my experience. A decade or so ago my kind local dealer lent me an SN1, HiCap, 200, 202, NAPSC to play with over the Christmas holidays. Source was CD5XS/nDAC. I tried every combination that would make music and started out sure I would go for the 200/202. After extensive auditioning, I found the SN1 and 200/202, both with HiCap, to be different in sound, but hard to separate in my preferences. In the end the SN/HC just edged it and that’s what I bought. At the time, there was a heated debate on the forum on the relative merits of these similarly priced combinations (which might be worth looking for in the archives) so I know that I was not alone in making this choice. Getting the HiCap DR’d improved things substantially (more than the DR upgrade on my XPS). So I would advise the OP to listen before jumping.
Roger
1 Like
It’s not purely down to the transformer. In fact, increasing output as impedence drops is a feature of transisters.
Valve amps are the opposite. They increase output as impedence increases or have flat output in relation to impedence. But never increase as impedence drops.
The Krell’s have some formidable design heritage. Though Class A isn’t my bag.
1 Like
That’s because transistors are low voltage / high current devices where as valves are high voltage / low current, so you get this characteristic with direct coupled valve outputs, whereas for the transistor amp it’s the lower of the current limits of the PSU or the transistor characteristics that’s the limiting factor. (It’s slightly different again with power MOSFETs.)
Of course with valve amps, the only way to get efficient matching is to use transformer coupling and that allows optimisation for the the effect of the actual impedance.
2 Likes
I would too, recommend listening first. However I do find the 202/200DR better as did the late Frank Abela when comparing 202/200DR to Supernait 2. He found the separates beat the SN2 and most comments I have seen on this forum agrees the SN2 is superior to the SN1. However there is always the difference in preference but I for one think the resolution advantage and better nuances in frequency extremes would benefit the op.
FWIW I’m still using 2 x Baby Nap 90’s with an IXO driving Allae’s. The pre amp used to be the matching NAC 92 but when that developed a fault I bought a NAC 202, NAPSC, Hicap DR.
I had the IXO and NAP 90’s recently serviced by Naim, while they were away I loaned an also recently serviced Olive Nap 250 to keep me going. The 250 subjectively gave a “bigger” sound with more dynamic but when I got the babys back from Naim I found I preferred the sound of those babys in active mode against the passive 250. Not as big sounding in terms of scale and prescence but those babys just sounded more musically involving with greater speed and timing, (PRaT). Subjectively in comparison the 250 sounded a bit sluggish like a dinosaur trying to do the hokey cokey.
Watts? The 90’s have just 32 per channel, but the Allaes are very efficient and in my 4 story cottage can go very loud if required, enough to trouble the neighbours down the street!
I think I would need at least a 282/250 DR combination to realise a significant improvement and that’s getting on for 8k?
To my ears those baby 90’s with IXO are certainly greater than the sum of their parts and in my view show that numbers of Watts are a least important consideration.
They have still been good enough to hold their own while I have been progressively upgrading my LP12 through Klimax Radikal, Keel, Ekos SE etc
4 Likes
Indeed, power hungry valve amps generally produce minimal wattage but are designed to work with very efficient, often horn loaded speakers. As you say it’s all about the right match, Horses for courses rather than numbers and spec.
Well - yes and no, AIUI. Watts describes the amps provided at a given voltage. Leaving aside the differences between DC and AC, it means that at a steady voltage it tells you what the amps are, and effectively the power. In that sense watts are, indeed, watts. However, with music (varying voltage) there is another important factor - slew rate. This describes the rate at which voltage changes - the time it takes for the voltage to change from, say, 0 volts to plus 40 volts. That affects the attack of the music - the speed, if you like, of the amplifier. Another aspect of music amplifiers driving loudspeakers concerns how the amplifier handles the back EMF - a voltage induced by the voice coil as the cone moves back under its own springiness. Put 40 volts through a speaker, then turn the voltage off. The cone will spring back to its initial position and in doing so acts as an electricity generator, inducing a voltage of the opposite polarity from the one that had displaced it in the first place. The amplifier needs to behave properly with this. I’m getting a little hazy here as it is a long time since I last read about this, but I’m guessing it needs to present, as near as possible, a zero resistance, so presenting no load to the speaker coil, allowing the coil to move as freely as possible. The point, though, is that back EMF can be a factor in the sound of an amplifier/speaker combination. From that point of view, watts is watts doesn’t necessarily hold.
2 Likes
I assume that is what is referred to as Damping Factor which Naim as I understand also have a different take on since their DF is below 20 and many others can have hundreds to many thousands and everywhere I read one claims that it should be high to control the speakers. Never understood why Naim has chosen this path either and what benefits there are with low DF?