Rotel rb850

Leisner · 29th August 2006, 03:55 PM

Hi

Does anyone have a schematic for Rotel rb 850 Amplifier?

anatech · 30th August 2006, 02:31 AM

Hi Leisner,
PM me. I have a fragment that may help. It's not complete, and it's not great but it may help you out.

-Chris

gni · 12th September 2006, 05:30 PM

I have been researching the Rotel RB850 amplifier for several years.

I have compared it to the schematics of similar Rotel amplifiers.

I saw a schematic on this forum that seems to have at least one error.
It looked like a scan of a photocopy that had things erased.

I have redrawn the schematic based on the one on this forum,
similar ones found elsewhere, and my RB850.

I will answer any questions you may have (as far as I know).

There is a thread with this similar question on this forum

Sincerely,

Chris Browne
Ground Noise Industries

gni · 12th September 2006, 06:57 PM

This was posted by member "transducer" and marked in red
by "gni"

gni · 4th October 2006, 09:29 PM

http://arts2001photo.lifepics.com/a/v.cfm?h=CB59E3A7

Until December 2, 2006

routhun · 5th October 2006, 12:18 AM

Hi Gni,

What are the mods you did on this amp? I have a vector research integrated amplifier VA-100 with exactly the same power amplifier stage, and would like to tweak that amp. How does this amp sounds? and the tweaks improved the sound?

Thanks,
routhun

gni · 13th September 2007, 12:34 AM

I emailed Rotel for the Technician Manual and they sent me one. . .it
has the Schematic and Bias Voltage (4mV across 0.22 ohms = 18.2mA)

I replaced the single turn bias adjust pot with a 15 turn unit. . .

anatech · 13th September 2007, 11:45 PM

Hi Chris,

Quote:

I replaced the single turn bias adjust pot with a 15 turn unit. . .

I am doing my best to figure out why you would do that.

You should install a new 270° unit at the very least, or put the old one back in after cleaning the slip ring and wiper.

What you people fail to realize is that the multiturn types generally have a much smaller contact area and are not intended to pass DC current.

I'm actually getting tired of hearing about this ill informed "upgrade".

-Chris

srh · 14th September 2007, 06:21 AM

Hi Chris,

The inability of multiturn pots to pass DC current explains why some of my projects won't work. Thanks for that, a great weight off my mind.

Cheers,
Steve.

vynuhl.addict · 14th September 2007, 06:30 AM

Anatech??, a multiturn trimpot is nothing but a single turn with a screw and a cog to allow easier adjustment than a very cheap open frame single turn trimpot. Its the same thing, just imagine a single turn, sideways and enclosed in a pretty sealed case thats helps protect from dust and dirt buildup.

Colin

29th August 2006, 03:55 PM	#1
Leisner diyAudio Member Join Date: Aug 2006	Rotel rb850 Hi Does anyone have a schematic for Rotel rb 850 Amplifier?

12th September 2006, 05:30 PM	#3
gni diyAudio Member Join Date: Sep 2006	Rotel RB850 Schematic Errors I have been researching the Rotel RB850 amplifier for several years. I have compared it to the schematics of similar Rotel amplifiers. I saw a schematic on this forum that seems to have at least one error. It looked like a scan of a photocopy that had things erased. I have redrawn the schematic based on the one on this forum, similar ones found elsewhere, and my RB850. I will answer any questions you may have (as far as I know). There is a thread with this similar question on this forum Sincerely, Chris Browne Ground Noise Industries

4th October 2006, 09:29 PM	#5
gni diyAudio Member Join Date: Sep 2006	Rotel RB850 Pictures http://arts2001photo.lifepics.com/a/v.cfm?h=CB59E3A7 Until December 2, 2006

5th October 2006, 12:18 AM	#6
routhun diyAudio Member Join Date: Mar 2005 Location: Sunnyvale	What are the mods you did on this amp? Hi Gni, What are the mods you did on this amp? I have a vector research integrated amplifier VA-100 with exactly the same power amplifier stage, and would like to tweak that amp. How does this amp sounds? and the tweaks improved the sound? Thanks, routhun __________________ routhun

14th September 2007, 06:21 AM	#9
srh diyAudio Member Join Date: Mar 2004 Location: Whangarei. NZ	Hi Chris, The inability of multiturn pots to pass DC current explains why some of my projects won't work. Thanks for that, a great weight off my mind. Cheers, Steve. __________________ The older I get, the more simplicity appeals.


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30th August 2006, 02:31 AM	#2
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi Leisner, PM me. I have a fragment that may help. It's not complete, and it's not great but it may help you out. -Chris

13th September 2007, 12:34 AM	#7
gni diyAudio Member Join Date: Sep 2006	I emailed Rotel for the Technician Manual and they sent me one. . .it has the Schematic and Bias Voltage (4mV across 0.22 ohms = 18.2mA) I replaced the single turn bias adjust pot with a 15 turn unit. . .

14th September 2007, 06:30 AM	#10
vynuhl.addict diyAudio Member Join Date: Mar 2006 Location: Vancouver, BC,Canada	Anatech??, a multiturn trimpot is nothing but a single turn with a screw and a cog to allow easier adjustment than a very cheap open frame single turn trimpot. Its the same thing, just imagine a single turn, sideways and enclosed in a pretty sealed case thats helps protect from dust and dirt buildup. Colin

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