rotel ra-971 mk11 tuning - diyAudio
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Old 8th June 2003, 06:06 PM   #1
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Lightbulb rotel ra-971 mk11 tuning

hallo to al the hifi gurus ...

I've got a rotel ra-971mk11 fer bout a year now.

Thinking of tuning it......can u guys out ther help me out ..
I think the amp is the same design as the ra-971 except for the pre-outs the mk11 has,so any tweak on the original i guess would work here.....

Would changing its op-amp be good idea .... its a OPA2604....

Well i guess its known to be slighty bright , n i guess it true.
I've AD825 in mind ...
How bout the caps ??Biggest area of improvement i guess do state the cap no as in the PCB cause i not a trained technician n i got no schematics of it .Any of u guys ??

talkin bout' cap , it uses BHC 10000uf caps for the PS.Two of them.Thought of doubling the value... any good candidates for caps??

do throw in the ideas n opinions , a reply is much appreciated..
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Old 9th June 2003, 01:15 PM   #2
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Join Date: Mar 2001
Location: Brazil
Default Re: rotel ra-971 mk11 tuning

Quote:
Originally posted by digitaldiablo
Thinking of tuning it......can u guys out ther help me out ..
I think the amp is the same design as the ra-971 except for the pre-outs the mk11 has,so any tweak on the original i guess would work here.....

Would changing its op-amp be good idea .... its a OPA2604....

Well i guess its known to be slighty bright , n i guess it true.
I've AD825 in mind ...
How bout the caps ??Biggest area of improvement i guess do state the cap no as in the PCB cause i not a trained technician n i got no schematics of it .Any of u guys ??

talkin bout' cap , it uses BHC 10000uf caps for the PS.Two of them.Thought of doubling the value... any good candidates for caps??
First of all you would have to answer to this question yourself: why and what do I want to change in the sound of this amp?

After this you may help yourself looking for some results you get when you change parts, like getting more detail or more bass. Sometimes a change is not necessarily good, and you spent lots of money, time and risked your amp for something you are not too satisfied with.

My suggestions for a generic upgrade will also depend on you getting a service manual to start with.

Analyze the circuit to see what might be improved.

Commercial products sometimes have weak areas where they have to compromise for cost reasons. Rotel is a quite fair company, so there shouldn't be so many areas to work on. That is before doing extensive changes that would require expertise and knowledge, which from your comments may not be up to the task. Please forgive this comment if I am wrong, but I am trying to help you not to go up a too bumpy and dangerous (and expensive) road.

To start with you should look at all blocking caps in the signal path. Except for the one at the power amp's input, you may be able to bypass most of them if you measure less than 5mV DC at the output of each stage, starting from the first chip.

If the capacitor is small enough, like 2.2uF or so, you can change it for a film type. You may also use better quality electrolytics, like some Black Gates, but prices may be high.

The 2604 is a good chip, and you may have to look well to find some a better one. Go here to find a good article on upgrading opamps:

http://www.zero-distortion.com/tests/opamps/opamps.htm

The AD826 might be a good dual to try instead of the 2604, but not on low noise stages like RIAA.

The power amp caps are alright if your amp is up to 100W in class AB power. You may upgrade the bridge diodes, but it's not guaranteed if you will get an improvement in all areas. Some may improve and some get worst.

Let's hope these comments are helpful. Get your schematic and come back for more.


Carlos
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Old 9th June 2003, 04:10 PM   #3
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Join Date: Jun 2003
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Default i got it .....a few more things ...

hi carlos .....
thanx fer ur through explanation n advice.I guess what ur sayin is very much through.
okay fer the moment i'll try to get the schematics , in fact mr carlos i've been doin fer the past few weeks .
I just can't get anybody to send me the schematics.
I would love to start tweakin' but since i guess the schematics is important i'll have to put a speed breaker . Maybe that 's good to.

Do any one have the schematics for the model ...?Do send me guys...pls...


Is it possible to trace the cct my examining the PCB...?
i've tried once but man, i don't have a clue of how things gets connected.Just here and there, quite bad for a final year electronics student i guess.

Just one more tech question, bypass caps , coupling caps and dc blocking caps.... all these are the same thing rite ??
What bout' decoupling caps ??
I guess this shows how ignorant i am, but well i'm learning now.

Again a reply would be much appreciated.
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