Rotel RC-850 Pre Amp + Rotel RB-870BX - diyAudio
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Old 28th January 2009, 07:15 PM   #1
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Default Rotel RC-850 Pre Amp + Rotel RB-870BX

OK, seeing as this is my favourite site of knowledgable people it'd be great if you could give me a hand with yet another question!

I recently got the Rotel RC-850 preamp and RB-870BW power amp I won on ebay, 102 for both of them (I thought it was a good price...?) and one question is nagging me... When were these originally released?

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Now I'm guessing they're from the 80's (?) but the seller told me he only knows as far back as when he got them in the mid 90's...


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RB-870BX with cover off... needed a good hoover out to get rid of years of dust! I've never owned anything with capacitors as scarily huge as those four 10000uF 63V beasts!
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RC-850 with cover off... absolutely pristine inside...
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Was very happy to see a good smattering of Nichicon Muse caps all over the preamps board
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Signetics NE5532s and more Muse caps in what I believe are the tone controls! Am I right in thinking the Signetics are as good as the NE5532 got?!
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Two of the four Signetics NE5534s used in the RIAA preamp section... Well off goes the Cambridge Audio RIAA preamp I previously used to eBay!
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The three 2SB817 PNP transistors and three 2SD1047 NPN transistors for one channel attached to a huge heatsink!

They don't seem to have ever been tinkered with, and as stock, they sound great IMHO, in terms of audio, a slight at first but the more I use them it seems like an extremely worthwhile jump from my Denon PMA-255UK integrated (30wpc vs the RB-870BX 100wpc into 8ohms!). There is so much power in reserve it's unbelievable, I'm not and will never go anywhere near what this beast of a power amp can throw out but the overhead is more than appreciated!

So being the tinkerer I am and the age of these units is there anything worthwhile doing?
I'm going to replace the captive lead on the power amp with an IEC three pin socket (this is also going to have a fuse holder to eliminate the separate one and I will also be removing the voltage selector switch to cut down on all the internal mains cable being crimped and jumping from place to place!!!)... but what else can be done with either the power or the pre amp?

I can get some BHC Aerovox 10000uF 63V caps to replace the stock ones in the power amp but is it worth it?

Any input gratefully recieved as ever!
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Old 7th February 2009, 11:36 AM   #2
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The caps in the power amp are of very high quality(they might even be BHC,or slit-foil types if I remember well).Try to look for any dates on the caps,that might help to learn about their age.Also check if the dates on caps are the same with the date on MUSE.I think Rotel were using Black Gates back then.
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Old 7th February 2009, 09:12 PM   #3
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I thought no one would reply to me here, thank you Panicos!

I'm going to get the lid off again and have a look to see what those 10000uF 63V caps were... I usually take a note of these things but I was in a rush to get the amp up and running and have a listen!
And besides I need an excuse to get the power amp back out to put in the three pin IEC socket and fuse holder!!!
I don't remember seeing Black Gates anywhere on the boards but what is in there seems of very high quality!

Anyway, the person that had the Aerovox's for sale sold them to someone else, and to be honest after running the units for a while I can't see what benefits there would be in changing them, all is working well and it's all sounding very good to my ears!

After ten years of owning separates I have finally got a set up where I don't think there's an obvious weak link in the chain! It's wonderful when you get to this stage!
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Old 7th February 2009, 09:22 PM   #4
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Yes it is wonderful when you are enjoying your music.The MUSE are very high quality caps,and generally those Rotel ranges all had good quality components.See also those Polystyrene caps,they are of excellent quality,very close tolerances and have a great sound.It was the time of RA820BX,840BX etc.....If I were you I wouldn't replace anything as long as they work ok and you like them.
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Old 9th February 2009, 11:20 AM   #5
Calvin is online now Calvin  Germany
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Hi,

in the German magazine Stereo some amps from the 800-Series were tested in mai 1987. In mai 1989 they tested the RC850/RB850 and in january 1992 the following 900-series RC960/RB969BX.
I still own a RB980BX I bought used more than 10years ago and man how has it been tortured in those years. The only repair it needed was app. 20 sets of fuses
Anyone wondering that I love that thing?

jauu
Calvin
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