I have been in contact with Rogue the last few days. Nick has been very fast with email responses and has told me that the Sphinx unit should have no noise. He suggested that interference on the AC line might be affecting the transformer but has said if it is shown to have an issue then they will look at it.
I will take it to the store I got it from and see how it compares to their floor unit. Rogue will give me a shipping label if there is an issue.
What alerted me to the hum initially was the fact I could hear it with the unit in standby mode, a little disconcerting. |
Simao.
It is quite true that the hum does not interfere with the music, my only issue is that if the unit is not operating as it should then I would definitely prefer to get that rectified, Rogue so far has been exceptionally helpful with emails answered within minutes sometimes. |
Smrex.
Interesting that you seemed to have ha a similar issue too. Did your unit hum also? Did you have Rogue inspect that unit? |
further to my last post, I have a rega brio in the TV room and the noise consists only of typical 'hiss', noticeable through the tweeter, little deeper in the mid unit and barely perceptible in the bass unit.
If I turn up the volume knob to maximum (no signal) there is no change that I can detect in the level of hiss and to the nature of the sound, it really does demonstrate to me how noisy the sphinx is, unacceptable by comparison. |
Thanks to all for suggestions and information. I will try the amp at a friends house to see if that changes anything as the first step to finding the issue. |
So an update on the humming sphinx.
I took it to the audio store and compared it to their shop floor model, both units demonstrated the same unit hum and noise from the speakers. The conclusion by the store associate was that it was a bit noisier than he expected but hadn't especially noticed though I think he had noticed the hum from the left speaker was louder than that in the right. He felt the unit hum was the transformer but was a bit perplexed by the hum from the speakers especially how the hum increased on the right side when the balance was turned all the way left!
Anyway I will assume for now that the unit is operating to spec even if it a bit noisier than ideal, I have provided Rogue with the details, although it is interesting that Rogue felt the amp should have no noise but the two units examined do give off some noise.
Only if the balance control was turned entirely left would the hum be audible over quiet music at close listening, in practice I don't use the balance anyway so it is not an issue. Overall I feel the sphinx could be quieter but for me the noise does not affect the music, it is simply not loud enough. Maybe Rogue could change something in the amp to quiet things down a bit in the future. If I had been more aware of the noise upon initial demo I might have been persuaded to try quieter models but as it stands I like the amp so its good for now. |
I've emailed Rogue again and as both units demonstrated the various noise I have asked if they think this warrants a return, I guess the ball is in their court so to speak, there is plainly an audible hum and the odd unequal hum from the speakers, if that is enough to convince Rogue their is an issue then so be it and I could send the unit to be checked/repaired, part of me does think that maybe that is just the design of the unit, admittedly that's not optimal but I'm currently not willing to start playing around with retail returns over something that doesn't actually affect my listening, I do however understand how some would not find it acceptable, $1500 is not crazy money but you still expect a quiet unit, there are plenty of cheap amps that are silent. |
I think what is perplexing about the hum is just how asymmetric it is: turn the volume up and it rises (slightly) on the right, reduces on the left, if you then turn the balance to the left the hum becomes much louder on the right but unchanged at the left. The hum from the right speaker in that instance really is audible from several feet away but in practice I can think of no instance where I would listen to the left channel only.
Anyway something for potential sphinx buyers to test when they audition the model. |
lowrider57/Reynolds853.
interesting that your two issues cover both of my units observations and both were repaired. (The testing was thorough, cables/speakers were switched, even different power cords used.
I'll see how Rogue responds next.
Thanks. |
I did ask Rogue if in their opinion the noise was an issue, Nick feels that the amp is working as it should saying that some transformer noise is possible and that some noise from the balance is normal.
I still have a three year warranty and unless there is a consensus from sphinx owners of a problem that is apparently fixable (say if somebody had the same issue and Rogue fixed it)then I'll currently accept the amp as it is, if the problem is noted later and is confirmed as fixable then I will look into it again. |
I'm glad I opened this thread at the very least it will make people aware of sphinx's noise and they can check it out for themselves specifically, it's the type of thing I wouldn't have thought of noting on a demo. |
Devilboy: so did the guy you sold the unit to actually get a repair?
I will give some feedback to my audio dealer (with the same noise in their unit) as to Rogue's response.
In this situation some people could insist on a return but to be honest the noise does not affect listening as it does not rise with volume increase. I think what bothers me is that there is some noise there and it's seemingly a tolerated part of the design which I think is sub optimal, in practice its not noticeable but the mere fact of its presence would bother many. In future I may just make sure that in any amp demos I actually get my ears up to the unit/speakers and play with the knobs a bit before I listen to anything playing!..... |
Actually, as it is a very quiet morning I did test the amp, the hum does change a bit as you raise the volume (went to 12 oclock to simulate loud listening), however it is asymetric...it rises in the right channel and reduces in the left!
To be honest if my dealer asked me if I wanted to change gear I would consider it but they have a no return policy as they give home demos and as this is supposedly working to spec they might not accept that as a request. IT is a shame as the rogue sounds pretty good. |
Reynolds853.
the transformer hum you described in the perseus, did that give any noise through the speakers also? Or was it only the hum from the unit itself? I do wonder if my 'variable hum' is related to that which I hear from the unit. |
I'll agree with Donjr, the customer service response is excellent.
Mark O'Brien did email me this morning. He suggests that the grounding for tubes and class D to be tricky and that in different environments there may be noise at the balance. He reckons that any sphinx in my set up would do the same. Perhaps its not ideal but as long as my unit is operating to spec then I can be assured that at least at future upgrade I can say it's working to spec.
On the topic of rogue I did also home demo the cronus magnum but I found it quite mushy sounding compared to the sphinx, maybe I'm not destined to be a full tube fan. I was actually surprised just how much softer the cronus was compared to the sphinx, still it made a street harp players recording sound incredibly seductive instead of biting.....and it made thinner or bright recordings much more manageable, but overall I prefer the more 'direct' sound of the sphinx.
I think being so used to SS that I'm used to the extra detail, plus im not sure I'm ready for hot 60lb metal and glass in my house!! |
Reynolds853.
The transformer hum is audible close up, certainly not several feet away as was yours. The balance hum is more the issue, to be honest if I tried for an exchange with the dealer they probably would oblige especially as they also felt it was a bit noisy. However I do like the amp and find my system engaging (I actually got the amp after suffering a nait 3's excessive gain in the line input for years, actually not as I was using an attenuator! I finally had enough, bought the sphinx and am now able to listen to cd).
I'll probably ask mark a few more questions after the weekend. |
A late follow through to this thread. I did unfortunately abandon the sphinx primarily because of the noise issue, I feel it is an otherwise competent unit but that level of noise was simply unacceptable, a sub $1000 NAD unit by comparison was practically silent. The sphinx comes in V.2 now and is described as having a lower noise floor, I wonder if this is a remedy to the hum/hiss of the original. I'd recommend the sphinx still but if an asymmetric hum/hiss concern you from speakers then I would check the level on the original version carefully. |
I have yet to purchase a replacement amplifier, for the time being I am using some pro equipment to run my speakers.
Jspively, apparently the original version sphinx does have this noise issue, some may not object but in comparison to say a NAD 365BEE that I auditioned it is very noisy, the NAD is almost dead quiet even with an ear to the speaker (at least with my ears). The sphinx does run very cool though which is a plus.
When I audition an amplifier now I check it for practicality first: noise, good use of the volume rotation (I hate sensitive designs that jump to full power almost immediately with loud CD's), heat. |
To go a bit further.
I did feel a bit burned with the noise issue on the amp, Rogue suggested it was a product of implementing valves and class D, unfortunately my dealer had a no return policy after home demonstrations, I did not notice it until the unit was purchased (I did not at that point check amps for noise on demo) I probably could have got a refund/exchange had I argued the noise issue but stayed with it as in practice during use it was not noticeable when sitting away from the speakers.
I accepted that amps will make some noise, until checking out the aforementioned NAD, it was easily the quietest amp i've (not) heard. My old naim nait 3 by comparison gives a slight audible hiss.
Hopefully sphinx V2 has fixed the hum/buzz and it is perhaps telling that V2 comes so very quickly after the release of the original model. I'm surprised such an obvious flew was not picked up prior to release of the original. It is disappointing as had the sphinx been quiet I would no doubt still own it. |
i see Steve guttenberg talks with the sphinx designer where he says some V1 units (1-2%) had an issue with noise related to DC offset? anyway not sure if that was something that could have been rectified back then but aggravatingly I did trade mine at a loss simply because of that very high noise floor. I enquired with rogue about this and my dealer back then, I should have been more aggressive on trying to get a refund. The only time I really felt like I'd been let down by a product in my audio. |
