Rotel RB-971 advise needed

hi everyone i'm new here

i have recently brought a second hand rotel RB-971 to replace my RB-850. i use the amp as a bridged mono to power a subwoofer. the RB-850 is 100 watts and the RB-971 is supposed to be 180 watts, the problem is that the RB-971 is no louder than the RB-850 and if anything has slightly worse sound quality.
i have read about replacing capacitors(which i am prepared to do)
my questions are-
if i do replace the "caps" will this improve the volume/quality issue.
are there any tests i can do myself (i have a multi meter) to check some of the other components ?

any help would be gratefully received
gaz
 

phase

Member
2004-10-04 11:59 pm
What is the ohms load of your subwoofer?

It looks like the 850 is rated for a 4 ohm load in normal operation, while the 971 isn’t.
Those initial power ratings are indicative and must be taken with a grain of salt.

Other construction features will determine how much load into lower ohms will perform from one amp to the next. It takes about twice the power usually to gain an appreciable difference it seems also, so that may be part of it as well.
 

phase

Member
2004-10-04 11:59 pm
Your previous amp will be better at the kind of load created by the speakers in their current arrangement. While the amps are similar, the voltage in the one you are using now is higher than the old one, and is limited to higher ohms loads by this design.


The 850 was rated at 4 ohms in stereo mode, and 8 ohms bridged. With the two 4 ohm speakers in parallel, you placed a load of 2 ohms onto a device made for 8 ohms, unless I’m missing something...

Maybe to wire the speakers in series, creating an 8 ohm load would be more agreeable with the amplifier.
 

phase

Member
2004-10-04 11:59 pm
I can’t recommend any basic books to read on this subject, just search for ohms law for starters.
There is a lot on the web, just have to start searching. If you don’t find anything right away, look for different terms for the subject you’re searching and try again.