need help for rotel amplifier

[suresh]

I have boutght a used Rotel Ra-970bx. i want to make some modification so that it sounds better. i have built dennis murphy usher 2 way and it sounds good with rotel. i want to know all the modifications so that i can improve my system. also at what bias current it sounds good ? please suggest .

Regards,
R.Suresh.

[suresh]

hope Homemodder can throw some light on my query.

[suresh]

Due to capacitor leakage in preamp section -16 volt regulator 2sb631k got short . i found zener diode also shorted . i replaced all in power supply section . then i found opamp AD827 gone bad due to high voltage entry. i dont have ad827 with me . can you suggest any other opamp in that position . time being i have opa2134 in hand .

[homemodder]

Originally Posted by suresh

Due to capacitor leakage in preamp section -16 volt regulator 2sb631k got short . i found zener diode also shorted . i replaced all in power supply section . then i found opamp AD827 gone bad due to high voltage entry. i dont have ad827 with me . can you suggest any other opamp in that position . time being i have opa2134 in hand .

Hi Suresh

I see you referenced for some tips before 3 years ago, sorry I mist it.

As for the opamp the opa2134 is a drop in replacement with no problems. I would however recommend you find a way to get the ad827 replaced as the sound of the amp will change somewhat and Im not sure whether youd like it, I dont. Be sure to have a look at the tone control IC as well, chances are good that one has been damaged as well.

[suresh]

yes i bought the amp in 2008 . it was working fine till yesterday. for tone control it had njm2114d , but i replaced both to opa2134 just now . yet to see how it sound's . i will give you the feedback tommorow of how it sounds. as per ypur suggestion i will buy and replace it with AD827 . i find it in rs components and farnell .

thank you for help .
also the amp had one more problem . the op offset in one channel is 100millivolt. i dont know how to solve the problem .

[suresh]

Hi Alex,
i had listened to the amp with opa2134 and found that the bass dosen't have authority . in the mid and treble region i am unable to find the difference. tell me which one is better ad826 or ad827 . both are available here in rs components . 827 costs 600 rupees and 826 costs 400 rupees . many people claim opa627 sounds nice . i would like to know your opinion on that . any input on the o/p offset in one channel ?