I recently acquired a pair of Ovator S-400s. They are in mint condition and it is obvious that they were well looked after by the previous owner. I keep my NAC52/Supercap/NAP250 powered up all the time. All three amplifier components are yet to be serviced. That is the next thing to be addressed! When the system is a rest, I hear a hissing from both Ovators, although this does not interfere when music is playing. My previous speakers, a tired pair of MkI SBLs were completely silent. I wondered if anyone knows why this hiss happens with the Ovator S-400. Thanks for any enlightenment that can be offered.
Maybe @Richard.Dane ?
Most likely normal. It’s a “thing” with Naim pre/power amps, but shouldn’t be intrusive, particularly when music is playing. It can be louder or softer depending on distance from the speaker, the speaker itself, condition of the speaker’s tweeters, acoustics of the room and the service condition of the electronics.
Interesting. I had the same Ovators for 11 years and never heard any hissing when driven by my 282/250/SC system. I hope you find the culprit.
Yes, but why with SBL he had no hiss at all?
Different speaker that works differently with the room?
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Quick googling suggests that SBLs and S400s had the same sensitivity, so one would expect the same sound level to any hiss. However the reality may be that although the average sensitivity may have been the same, the SBLs might have rolled off more or lower at the treble end than the Ovators, whether that was the case when both were new, or just in the pairs you had. As I assume you’re aware, hiss is high frequency noise, generally only audible from the tweeter, so any greater output at the treble end could make previously inaudible hiss aidible.
Does music through the ovators sound “brighter”, with, for example, cymbals more prevalent than with the SBLs? If so this would support that hypothesis.
I find that the sound from the Ovator S-400s is brighter but not uncomfortably so. The are certainly more punch than the DBLs, although my SBLs are tired. Cymbals are indeed more prevalent with the SBLs.
Then indeed I think that is the reason why you hear tge hiss now, but didn’t with the SBLs.
S400s with either Nova, NAP250DR, NAP300DR or NC250 don’t in my experience experience hiss.
I wouldn’t profess to know why hiss is present. SBLs versus S400, there is a Naim sound from each, but S400s brighter than SBLs not so sure.
Worth considering the following -
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Ovator S400s also need careful set up and the torque settings as well as the torque settings in the base, should be checked periodically in accordance with the data sheet. The issue has been discussed previously on the forum.
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Speaker cables might also be checked and both for placement / routing and how good are the joints.
Use the Ovator speaker plugs, which Naim recommend. -
Realistically very few pairs of S400s, indeed all Ovators, are less than ten years old now, many older. Passive versions which of course internal crossovers are likely to benefit, at some stage, from the crossover being serviced.
I purchased a pair around twelve years old very recently, briefly auditioned on purchase.
Went direct to Steve at Wilmslow Audio, who confirmed they are in fine condition and expected to benefit from crossovers being serviced. Likely worth a call to them, who now have recent experience of working on a pair, with a view to a check over.
It is worth noting that hiss comes from amplifier electronics (also can come from source electronics). Hiss is not created by speaker cables, connectors, crossover, speaker box screw looseness etc, though these factors potentially could influence hiss level if they either reduced HF energy (lowering hiss) or, for hiss altered by volume control setting, if those aspects reduced lower frequency energy resulting in use of a higher volume setting.
Hiss from the power amp is unaffected by the volume control. If the hiss is indeed there when volume control is at zero or mute is selected, and wasn’t with the SBLs, then it can only be increased efficiency of the speaker at the HF end relative to the SBLs.
The only difference then comparing two speakers is the mount of high frequency energy from one that reaches your ears relative to the rest of the frequency range. If the speakers are positioned with the tweeters in the same positions, and listening position unchanged, the major consideration then is the output of high frequencies relative to lower frequencies by each speaker, primarily in terms of direct radiation towards you, though room reflections from non-direct radiation will have an effect. If the Ovators are nearer to the listening position than were the SBLs then of course that will increase the sound level of any hiss from the ppwer amp.
The tweeters of the SBL’s are also tilted. I’ve always found the imaging of IBL’s better than SBL’s since they’re tilted less.
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I suggest to try Ifi dc blocker between the 250 and the power cord. I had some hiss too, which quite totally disappeared with the Ifi dc blocker.
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