Rotel RB985 - squealing

Discussion in 'AV Pre-Amp/Processors & Power Amps' started by sergiup, Feb 13, 2014.

  1. sergiup

    sergiup
    Distinguished Member

    Joined:
    Apr 29, 2008
    Messages:
    7,777
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Location:
    SE London
    Ratings:
    +4,165
    It's actually hard to describe; the amp itself works absolutely fine, which is great for its age. However, when I turn it off, after a few seconds I can hear a "squealing" of sorts out of some speakers, starting at quite a high frequency and decreasing. It only lasts a few seconds, and there are no humps or any other issues.

    Is that most likely the capacitors draining, and is it something I should get fixed? It doesn't sound like something urgent to be honest, though I'd imagine that given its age, a re-cap would be good for it anyway. Would I have to replace all of them or just the four big caps?

    Thank you!
     
  2. Glen B

    Glen B
    Active Member

    Joined:
    Jan 26, 2014
    Messages:
    84
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    11
    Location:
    New York
    Ratings:
    +11
    I would not worry. Yes, its the caps draining. You're hearing it because the amp has no output relays.
     
  3. sergiup

    sergiup
    Distinguished Member

    Joined:
    Apr 29, 2008
    Messages:
    7,777
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Location:
    SE London
    Ratings:
    +4,165
    Thank you Glen! That's what I figured, if it becomes bothersome at some stage I'll look into it, but by then, I would possibly have a different power amp anyway... Mind you, it's doing a sterling job so far!
     
  4. tris101

    tris101
    Active Member

    Joined:
    Nov 19, 2010
    Messages:
    256
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    28
    Ratings:
    +41
    I think from memory.. from day one there was always a small amount of noise on switch off and switch on, clicking if I remember right. On power down sometimes there was very quiet addible whistle as the caps drained you had to listen for it. the other ones I the shop did the same so I guessed it was part of the design. replacing the caps certainly would not hurt start with the 4 big ones but all of them would be a good idea.
     
  5. sergiup

    sergiup
    Distinguished Member

    Joined:
    Apr 29, 2008
    Messages:
    7,777
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Location:
    SE London
    Ratings:
    +4,165
    Thank you, Tris! I didn't in any way intend to alarm you, I genuinely thought it was either by design or just age, neither of which would've warranted coming back to you :)
     
  6. tris101

    tris101
    Active Member

    Joined:
    Nov 19, 2010
    Messages:
    256
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    28
    Ratings:
    +41

    No problem.. I was just try to reassure you I think its by design as it has made some noisy from day 1 as did other I demoed at that time. My new yamaha 3010 is not as good as my old my old lexicon rotel combo. At some point maybe I will go back to pre power combo.
     
  7. sergiup

    sergiup
    Distinguished Member

    Joined:
    Apr 29, 2008
    Messages:
    7,777
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Location:
    SE London
    Ratings:
    +4,165
    Thank you gents; it is indeed a really good power amp for its age, I haven't heard it struggle at all so far in any way.

    Tris, you could try just adding a power amp to the RX-A3010, at least to start with. It's recently started to strike me as being quite ballsy when AVR manufacturers state things like "230W x 9" (with various caveats, conditions etc), when just on the back on the AVR you can clearly see a maximum stated power draw of 490W... Honestly, I believe that all amp manufacturers (regardless of whether it's a power, AVR or integrated stereo) should be forced to state the maximum, continuous all-channel output, and only after that any hypothetical other measurements. It's never all about total sustained output anyway, but it's a much better start than 1-channel driven figures with high distortion and so on.
     
  8. Glen B

    Glen B
    Active Member

    Joined:
    Jan 26, 2014
    Messages:
    84
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    11
    Location:
    New York
    Ratings:
    +11
    In real world use on movie material, all channels are never called upon to deliver their maximum power. The surrounds carry little information. Any channel of an AVR is capable of delivering the maximum rated per-channel power. There is no real need for all channels to deliver max power simultaneously. Knowing this, AVR manufacturers can deliberately skimp of power supply size. This is not necessarily a bad thing. The savings can be invested in the latest bells and whistles, yet keep the product at an affordable price. Producing AVRs capable of delivering maximum rated power into all channels simultaneously, will result in prices that are significantly higher than present. IMHO, the average Joe would be paying for power that is never used in the real world.
     
    Last edited: Feb 16, 2014
  9. tris101

    tris101
    Active Member

    Joined:
    Nov 19, 2010
    Messages:
    256
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    28
    Ratings:
    +41
    The Yamaha 3010 is good and price was right but it is too complicated for its own good, loads of dsp modes that never get used etc. I think a more basic design might be better, keep it simple.. At some point I may look to add a 7 channel power amp into the mix. The number game the av amp manufactures play is bit of joke 1 channel at high THD so they can quote high numbers.

    The Rotel had bags of power even know it was rated at 100W, it was nice amp.
     

Share This Page

Loading...