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Seeking suggestions for improving a vintage Rotel RA-210

I

ignoramustot

Active Member
Hi everyone. Hope I'm posting this in the correct forum. (I mostly visit the Sansui forum.)

I've recently had a friendly local tech perform the famed @Leestereo upgrades to my Sansui AU-555A and it's singing very sweetly indeed.

My wife has an little old Rotel RA-210 amplifier from the early 1970s that she's owned for over 35 years and of which she is very fond.

The return of my Sansui has sparked some domestic friction! You guessed it: "When are you going to spend the same money and attention on my amp as you have on yours??!!"

Do any members have any suggestions for improvement of the very simple and low-powered Rotel RA-210, please?

Is the Baxandall diode modification possible on this amp? (I'm a technical ignoramus and can't read circuit diagrams.)

I found this basic upgrade but would be interested in any other suggestions for improvement within the limits of the humble original design.
https://www.hilberink.nl/codehans/luxman69.htm

My wife uses her RA-210 almost exclusively for listening to vinyl, so any suggestions for the phono section would be especially welcome, please.

Thanks in advance to the generous sharing and helping culture of this site.

Cheers,
Rob in Melbourne, Australia
 
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I should add that the Rotel was recapped about three years ago but by a different tech from the guy who did my Sansui and I suspect rather ordinary parts were used.

Also it is making a horrible loud crackling through the speakers in the few seconds after it's switched off, and has been taken out of service at the moment because of that. So if anyone has a suggestion of what to check or change there, that would be helpful.
 
The Rotel RA-210 appears to be a relatively simple capacitor-coupled design and it's likely that many of the AU-555A upgrades/modifications can be adapted for it. Do you have pictures of the interior of the RA-210 that you can post and/or a list of work done during the recap?
 
Many thanks for your reply! :bowdown: I don't have any pictures available today but I will try to take some and post them in the next few days. Are there any particular angles or views that would be most useful?
Thx, Rob
 
ignoramustot said:
I should add that the Rotel was recapped about three years ago but by a different tech from the guy who did my Sansui and I suspect rather ordinary parts were used.

Also it is making a horrible loud crackling through the speakers in the few seconds after it's switched off, and has been taken out of service at the moment because of that. So if anyone has a suggestion of what to check or change there, that would be helpful.
Click to expand...

I really feel your pain. The Rotel RA-210 was a basic integrated amp that was made with rather ordinary parts, so anything is possible. Whether or not the time, effort, or money are worth it is entirely up to you and your wife. My guess is that your wife will ultimately decide. :thumbsup:
 
ignoramustot said:
...I don't have any pictures available today but I will try to take some and post them in the next few days. Are there any particular angles or views that would be most useful?...
Click to expand...

Multiple angles to allow identification of the replacement components and pictures of the solder side (if any components were added there).
 
To be honest that is not an awful lot of amp to work with. If for sentimental reasons (or the sake of your marriage) you want to keep it in service, you got two options. One is to optimize it. A decent recap' should have done a lot for that. You might also flip some low noise transistors, clean and relube the potmeters and stuff like that. The other option is to buy a brand new amp module. Stack it in the little wood-box, together with some second hand tranny and you can have actually nice sound for little money. While it still looks like the old amp. If you got some size-friendly BPC amp laying around, then transplanting that one might also be an option.
 
Just take her shopping for a new amp. If she's serious about audio, her sentimental attachment should subside after the first demo.
 
Okke 70s said:
To be honest that is not an awful lot of amp to work with. If for sentimental reasons (or the sake of your marriage) you want to keep it in service, you got two options. One is to optimize it. A decent recap' should have done a lot for that. You might also flip some low noise transistors, clean and relube the potmeters and stuff like that. The other option is to buy a brand new amp module. Stack it in the little wood-box, together with some second hand tranny and you can have actually nice sound for little money. While it still looks like the old amp. If you got some size-friendly BPC amp laying around, then transplanting that one might also be an option.
Click to expand...

Absolutely it's a very basic bottom of the range little amp that never gets pushed hard. We're not looking for audiophile or modern standards here.

It's the sentiment, folks. This amp, basic AGS turntable and her big collection of secondhand blues and jazz LPs got my darling through some tough years well before I met her. A heart transplant wouldn't go down well at all, just like she'll never part with her secondhand vinyl, crackly though much of it is. Sometimes we just have to respect emotional connections founded in favourite music.

Thanks for the suggestions, nonetheless.
 
I have one of these. I did the minimal amount of upkeep..... although I still have a short list to complete. But I did replace some resistors that were out of spec and/or did not match close between channels...I think it was about 6 resistors. I updated the power supply and output coupling caps and maybe some others, I'd have to look at my notes. But for sure I agree with the link (blog) that you posted; the power transformer is the most limiting item in this little amp.

It's a beautiful little amp and sounds nice. For sure it's not gonna blow the doors and windows off the house.

I gave up the vinyl pursuit years ago and only drive this with a CD player or a portable media source, so I've done nothing to the phone stage.

Lastly I got this amp from a local antique dealer silent auction for $11.
Super clean and it did not look like there was ever any service done.

It resides in my collection next to my Luxmans, Sherwoods, NADs, Marantz, B&O and newly added Denon DRA-755 (which is amazing)....sorry for the tangent.

Good luck on the upkeep.
 
Ok, I eventually got around to lifting the top and bottom lids on the little old Rotel to take some pictures as suggested months ago. Not sure if these will help prompt anyone with suggestions, but here they are. First time loading media here so forgive me if I'm doing this wrongly... Please excuse my amateur work with a low-quality smartphone...
Thanks and cheers, Rob

IMG_20230410_170627023

IMG_20230410_170627023

Rotel RA-210 front top
IMG_20230410_170655673

IMG_20230410_170655673

IMG_20230410_171122481

IMG_20230410_171122481

IMG_20230410_171236876

IMG_20230410_171236876

IMG_20230410_171443194

IMG_20230410_171443194

IMG_20230410_171524863

IMG_20230410_171524863

IMG_20230410_171816134

IMG_20230410_171816134

IMG_20230410_172851359

IMG_20230410_172851359

IMG_20230410_171216946

IMG_20230410_171216946

View from above front
IMG_20230410_171621060

IMG_20230410_171621060

IMG_20230410_172150857

IMG_20230410_172150857

Underside from front
IMG_20230410_172202633

IMG_20230410_172202633

Underside from front
IMG_20230410_172252583

IMG_20230410_172252583

Underside from rear
IMG_20230410_172230705

IMG_20230410_172230705

Underside from rear
 
Last edited:
Leestereo said:
Multiple angles to allow identification of the replacement components and pictures of the solder side (if any components were added there).
Click to expand...
Please refer to pics just loaded. I hope they are useful. The solder as seen from underside seems thick and/or fresh - not sure if that was touched up when it was recapped three years ago. There also seems to be a small resistor attached to the underside - I don't know if that was original placement or added in the recent work.
Thx. Rob
 
Hey,

Im planning on replacing a few transistors in my RA-210 following advice from the service manual. I cant find the original transistors but Ive done some research and found some subsitutes, does anyone see any issue with the following subs?

Tr501, 502/Tr601, 602
* Description: Transistor, 2SC644 = KSC2690AYSTU
Tr503/Tr603
* Description: Transistor, 2SC828 = KSC2690AYS
Tr505/Tr605
* Description: Transistor, 2SA564A = MJE2955T
Tr506, 507/Tr606, 607
* Description: Transistor, 2SD317 = MJE15030G

Thanks in advance
 
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