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Post by Greg on Apr 27, 2017 11:52:42 GMT
Pete, I've suffered from this sort of thing with valve amps before, particularly those with E/I transformers which I think your Oto has. A couple of things to try. Transformers generate a field around them that can interact with the fields generated by transformers in closely located neighbouring equipment, particularly if located immediately above or below the noisy item. Do you use a rack? Try putting space between kit, preferably on a horizontal level. I know of one kit Pre amp with E/I TX's that needed to be at least a metre away from its PSU to be totally silent, and there I mean silent on a scope.
The TX's could be buzzing simply because the tension the plates were subjected to on assembly has relaxed a little. This sort of mechanical buzz is not uncommon in many valve amps. Try tightening the anchor bolts that run through the plates of the TX. This however, doesn't always bring a fix and my very best solution on one of my amps was to simply mount the amp on a set of sorbothane half circle supports, cheaply available from eBay. This turned one noisy amp audible from the listening position during quite passages of music into a completely silent amp leading to one happy owner! Good luck, I understand your frustration and hope you get it sorted soon.
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Post by orbscure on Apr 27, 2017 12:54:42 GMT
Pete Just looked on another forum, where at least 3 Oto owners observe mild transformer hum and conclude it is normal and acceptable. Like my Fender Blues Junior perhaps. If it ain't broke... This comment from that thread may be of interest "Check that all the screws (case screws and transformer mounting ones) are present and tight. The case is relatively large and the panels are un-braced and can resonantly enhance any acoustic transformer hum. If it used to be quiet but it's suddenly started humming then it's just possible that one or more valves have started drawing excess HT current (age, bias drift etc can cause this). If you have a multimeter and are happy that you can work safely on live equipment then there are ways of checking these things." Note - careful taking the lid off a valve amplifier - the capacitors can retain lethal charges. Its definitely one of the more annoying buzzes Richard, the type that when sitting 6ft away, you can clearly hear during the quieter passages of music. Its also buzzed since day one and when I recently had her apart to clean the fascia, I ran around the various screws and bolts nipping them up where necessary. I don't have a multimeter, but even if I did, I have a healthy enough respect for electricity and leave that to the experts  A couple of things to try. Transformers generate a field around them that can interact with the fields generated by transformers in closely located neighbouring equipment, particularly if located immediately above or below the noisy item. Do you use a rack? Try putting space between kit, preferably on a horizontal level. I know of one kit Pre amp with E/I TX's that needed to be at least a metre away from its PSU to be totally silent, and there I mean silent on a scope. The TX's could be buzzing simply because the tension the plates were subjected to on assembly has relaxed a little. This sort of mechanical buzz is not uncommon in many valve amps. Try tightening the anchor bolts that run through the plates of the TX. This however, doesn't always bring a fix and my very best solution on one of my amps was to simply mount the amp on a set of sorbothane half circle supports, cheaply available from eBay. This turned one noisy amp audible from the listening position during quite passages of music into a completely silent amp leading to one happy owner! Good luck, I understand your frustration and hope you get it sorted soon. I have a four shelf bespoke oak shelf rack Greg. The Oto sits at the top, next shelf has an LFD Phonostage MC and a Chord Hugo TT DAC, the next has a Primare CDP and the bottom shelf has the LFD PSU, a Korus Audio Music Server (PC) and a MCRU PSU for the Chord DAC. I've had all manner of different kit on different shelves, but the Oto has always buzzed since day one. I have indeed considered adding something between the AN transformer and its chassis, but I think I'll save that exercise for a rainy day Pete |
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Post by pinkie on Apr 27, 2017 13:23:06 GMT
Pete If the Oto has buzzed from day 1, and you have never known it in an unbuzzing state, but that happens to be exclusively in your "new" Surrey home, and all the other kit you list is sitting on a rack and not buzzing, then I would look to the Oto and not the mains. By all means get your electrician friend to do free tests, but I would invest money in getting the amp checked out by a competent technician before investing in mains products to fix a problem that probably isn't mains. If he does measure DC on the mains, it would be interesting to know the value. If the Oto has buzzed from day 1 and is still under warranty, there's your starting point. Hope you get it sorted soon |
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Post by Deleted on Apr 27, 2017 15:30:04 GMT
Does this help with the Oto? link |
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Post by julesd68 on Apr 27, 2017 15:42:50 GMT
If the Oto has buzzed from day 1 and is still under warranty, there's your starting point. But Pete has had a number of amps that have the buzzing issue |
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Post by pinkie on Apr 27, 2017 15:56:45 GMT
If the Oto has buzzed from day 1 and is still under warranty, there's your starting point. But Pete has had a number of amps that have the buzzing issue He no longer has those amps. Other equipment is not affected - a lot of other equipment. If mains is responsible for a buzzing transformer, it will be DC, which we assume the MCRU gizmo is capable of blocking, or over-voltage. If he has an electrician coming round it will be simple to check the voltage whilst the equipment is buzzing, but it seems almost inconceivable that it has been consistently overvoltage since he acquired the Oto. If I were in his situation I would get the equipment that has an apparant fault checked since it has apparently had the problem from new. If you forget for a moment the enthusiasm have for attributing everything to the mains, then the man in the street faced with a product malfunctioning would start by getting the product checked. I recall something said to me. "Sometimes things are as they seem." |
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Post by pinkie on Apr 27, 2017 16:02:05 GMT
Does this help with the Oto? linkProbably not. It's talking about noise from the speakers not mechanical noise in the device, and Pete has confirmed it is a mechanical noise. And actually there are a few bits in there, like lifting ground, which are, how shall we say, not PC. And not necessary. Good grounding is the solution - but that's for another day. Pete's issue appears to be a transfomer buzz - not hum on the signal. |
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Post by orbscure on Apr 27, 2017 18:24:18 GMT
Many thanks for splitting the discussion ChrisB To resume where we left off earlier... back home from work, I moved the Oto to the front room and kitchen and it buzzed with or without the filter. I then plugged the AE sub into the same filter with no changes there either. With regards pinning the blame on the current Oto amp, I think its worth my repeating one of my earlier comments, in that I've used the same two plug sockets for the last 3 years and can confirm what has and hasn't buzzed: Quad 306 or Quad 406 - no buzzing, but Croft Micro 25 Basic pre buzzed Monarchy SM70pro - buzzing NVA A40 MKII monoblocks - no buzzing, but high frequency treble ringing, confirmed as local to me as RD tested same amps at NVA towers, in my presence, without the issues Audio Note P-Zero monoblocks - buzzing Restek MAMP monoblocks - buzzing AN Oto SE - buzzing That is a mixture of valve/solid state hardware, some suffering with the same issue as the Oto, some not... anyway, until I've had the tests outlined earlier, guessing adds very little and the results should point us in a better direction |
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Post by ChrisB on Apr 27, 2017 18:25:57 GMT
You're welcome - I hope I got it all while keeping sense to both threads.
Sometimes that's really tricky!
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Post by pinkie on May 5, 2017 13:43:28 GMT
Any progress?
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Post by orbscure on May 5, 2017 17:14:01 GMT
Not at the moment Richard... after an initial flurry of playing about here, my electrician friend is mega busy at the moment, so he is going to try and fir me in next time he is in my area and when I'm available. David @ MCRU kindly accepted the DC filter back under his no quibble 30 day money back guarantee, so kudos to him for that |
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