Rotel RB-970BX problem

00dc2 · 17th September 2010, 02:35 AM

I bought one of these power amps off ebay hoping that i could drive it from the output of my total bithead (DAC and headphone amp)

Headroom Total Bithead - Headphone Amplifier | HeadRoom Audio

I connected it up and slowly ramped the gain on the bithead and i heard a slight noise from the speakers and the rotel powered off and now doesnt power on at all.

I know i am supposed to use a preamp, but I didnt think the input to a power amp would be so sensitive. The manual for the rotel says the overload level is 5V and i assumed the USB powered headphone amp can only got that high at the most.

I've just downloaded the service manual and will take a look at that but i have no experience doing this sort of thing so any help would be really appreciated.

bob91343 · 17th September 2010, 03:04 AM

Start with the power line and main switch and fuse if any. If you get power to the transformer, see if you get power out of the rectifiers.

If you don't get power to the transformer, maybe you blew a fuse. Yeah, a volt or so at the input of a power amplifier will drive it pretty hard.

00dc2 · 17th September 2010, 08:12 AM

The rail fuses blew, i replaced them and she plays fine through the total bithead.. i just had the volume turned up too high in windows.. i turned that right down and started from there...

now i set the volume to 50% in winamp or mpc and then use the vol control on the little headphone amp starting at 0.. gives good volume control

What is the chance that i damaged the rotel by overdriving the input on it?

birdyman · 17th September 2010, 03:34 PM

Depends on your head phone amp output voltage level.
In reality, Not so high of chance.........is it??

00dc2 · 17th September 2010, 04:55 PM

not entirely happy with the rotel, it is hissing when there is no music playing.. i'd like to figure out if its the headphone amp that is feeding it or the rotel itself

with the headphone amp plugged into the rotel but with the input level/gain turned down to zero there is a hiss.. when there is nothing connected to the input of the rotel it produces complete silence..

i wonder if the headphone amp has some dc or i dunno some noise or there is a mismatch between its output and the rotel's input.. cos the headphone amp plays very cleanly with my Sennheiser HD600s

i am guessing that the headphone amp isnt really that clean and the headphones are far less sensitive to noise on their inputs than the rotel.. but if only i could find a nice and clean source to drive them with to really test them.

djk · 17th September 2010, 09:14 PM

A quick fix might be a 1:1 transformer.

EDCOR - S2S10K/10K

Andy5112405 · 19th September 2010, 10:53 AM

Try running with no input or, even better a shorting plug on the input of the Rotel. The Power Amplifier should be virtually silent in this situation.

I would suspect that your "hiss" is coming from the output of the computer.

00dc2 · 19th September 2010, 11:10 AM

when i run it with the input open circuit it is silent.. your suggesting i short the inputs? is that a good idea (gulp)? (i have no idea)

silence with open circuit inputs suggests the amp is in good nick?

Andy5112405 · 19th September 2010, 02:40 PM

If it's silent with NO INPUT there is no need to try it with shorting plugs.

The amplifier sounds good to me.

00dc2 · 19th September 2010, 09:56 PM

great, thanks for your help!

17th September 2010, 02:35 AM	#1
00dc2 diyAudio Member Join Date: Sep 2010	Rotel RB-970BX problem I bought one of these power amps off ebay hoping that i could drive it from the output of my total bithead (DAC and headphone amp) Headroom Total Bithead - Headphone Amplifier \| HeadRoom Audio I connected it up and slowly ramped the gain on the bithead and i heard a slight noise from the speakers and the rotel powered off and now doesnt power on at all. I know i am supposed to use a preamp, but I didnt think the input to a power amp would be so sensitive. The manual for the rotel says the overload level is 5V and i assumed the USB powered headphone amp can only got that high at the most. I've just downloaded the service manual and will take a look at that but i have no experience doing this sort of thing so any help would be really appreciated.

17th September 2010, 09:14 PM	#6
djk diyAudio Member Join Date: Feb 2001 Location: USA	A quick fix might be a 1:1 transformer. EDCOR - S2S10K/10K __________________ Candidates for the Darwin Award should not read this author.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Rotel RQ-970BX schematic wanted	Sjef	Analogue Source	7	3rd July 2011 10:47 PM
Rotel RA-970BX schematic needed	agoraphobic	Solid State	2	26th June 2010 09:15 AM
Rotel RB 1080 Glue Problem	birdyman	Solid State	3	5th June 2010 07:16 PM
Problem with Rotel RB-985 MKII 5 channel home cinema amplifier...	hoppaz	Solid State	2	9th April 2009 08:04 AM
Rotel RC-850 Pre Amp + Rotel RB-870BX	bleachershane	Analog Line Level	4	9th February 2009 11:20 AM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

17th September 2010, 03:04 AM	#2
bob91343 diyAudio Member Join Date: Mar 2010	Start with the power line and main switch and fuse if any. If you get power to the transformer, see if you get power out of the rectifiers. If you don't get power to the transformer, maybe you blew a fuse. Yeah, a volt or so at the input of a power amplifier will drive it pretty hard.

17th September 2010, 08:12 AM	#3
00dc2 diyAudio Member Join Date: Sep 2010	The rail fuses blew, i replaced them and she plays fine through the total bithead.. i just had the volume turned up too high in windows.. i turned that right down and started from there... now i set the volume to 50% in winamp or mpc and then use the vol control on the little headphone amp starting at 0.. gives good volume control What is the chance that i damaged the rotel by overdriving the input on it?

17th September 2010, 03:34 PM	#4
birdyman diyAudio Member Join Date: Jan 2010	Depends on your head phone amp output voltage level. In reality, Not so high of chance.........is it??

17th September 2010, 04:55 PM	#5
00dc2 diyAudio Member Join Date: Sep 2010	not entirely happy with the rotel, it is hissing when there is no music playing.. i'd like to figure out if its the headphone amp that is feeding it or the rotel itself with the headphone amp plugged into the rotel but with the input level/gain turned down to zero there is a hiss.. when there is nothing connected to the input of the rotel it produces complete silence.. i wonder if the headphone amp has some dc or i dunno some noise or there is a mismatch between its output and the rotel's input.. cos the headphone amp plays very cleanly with my Sennheiser HD600s i am guessing that the headphone amp isnt really that clean and the headphones are far less sensitive to noise on their inputs than the rotel.. but if only i could find a nice and clean source to drive them with to really test them.

19th September 2010, 10:53 AM	#7
Andy5112405 Banned Join Date: Nov 2006 Location: Torpoint	Try running with no input or, even better a shorting plug on the input of the Rotel. The Power Amplifier should be virtually silent in this situation. I would suspect that your "hiss" is coming from the output of the computer.

19th September 2010, 11:10 AM	#8
00dc2 diyAudio Member Join Date: Sep 2010	when i run it with the input open circuit it is silent.. your suggesting i short the inputs? is that a good idea (gulp)? (i have no idea) silence with open circuit inputs suggests the amp is in good nick?

19th September 2010, 02:40 PM	#9
Andy5112405 Banned Join Date: Nov 2006 Location: Torpoint	If it's silent with NO INPUT there is no need to try it with shorting plugs. The amplifier sounds good to me.

19th September 2010, 09:56 PM	#10
00dc2 diyAudio Member Join Date: Sep 2010	great, thanks for your help!

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)