RCA 9289 tube amplifiers


The RCA 9289D was the final version of this great 200W amplifier.  It features four 6550 in the output stage and an interesting power supply with OD3 regulators.  My father designed the final version of this amp for RCA and we have several available.  I'm testing the water to see if there's still a market for this excellent amp before I start recapping them, or whether folks would prefer them bone stock.

cdietze

Interesting can you post some photos?

Is this a mono amp? I'm guessing it must be fifty/sixty years old! Certainly new caps throughout would be a prudent upgrade!

Without a doubt check them, replace needed 'out of spec' resistors, caps, ...

I would NOT go for 'upgraded, tighter, better' resistors, caps, just stay within original performasnce specs as shown of the OEM parts list.

A particular owner could chose to 'upgrade' for themselves, but you don't want to change the magic sound the original 'in-spec' parts provided.

Dad always favored rebuilding them with Sprague Orange Drop coupling capacitors.  The large can caps generally are OK.  There's no reason to change out the resistors; that's a personal choice, not an engneering choice. 

 

And Jasonbourne52, this is a mono amp.  I'll take some images next time I'm at teh storage space. 

Dad always favored rebuilding them with Sprague Orange Drop coupling capacitors.

That is because back in those days they were the only game in town. A lot has changed since then! There is no way I'd use orange drops for any kind of rebuild or repair at this point- they are simply outdated.

If you are selling a set of these amps I would leave them bone stock, don't do anything to them and let the buyer worry about that. Anything you do to them can damage the collector value, even though they may barely work because the filter capactors are shot.

OTOH if you do replace filter caps, the only way to do it is to do it so well that no-one can argue with the parts choice and workmanship.

 

i agree w Ralph unless you have a significant non refundable deposit from a client making the individual component selections....

please do keep us apprised of how this all turns out..

@hilde45  there is your Orange drop answer, i may....have dated myself....

@tomic601 Thanks. I don't know how many "orange caps" there are out there. I'm replacing mine with Mundorfs and if it goes south, I'll change them back.

@tomic601 and @hilde45 are you guys telepathically linked? 😁 I see no posts from Hilde in this thread about orange drops? And as usual great answer from Ralph.

@jond sort of..I mentioned in a thread Hilde started that i ( and others ) had been rolling caps as tweaks way back when Sprague Orange Drops were a " thing "...I thought it amusing Ralph weighed in here....

back to the music....

I thought it amusing Ralph weighed in here....

One of my employees refurbished a pair of the little brothers to this amp, that he got from an old theater. IIRC they made about 60 watts using a pair of 6550s. 

 

That amp was probably a 12182.  They were stock with 6146 output tubes but easily converted to 6550's.  The 6146's ran away easily. I had one about 40 years ago and one got so hot it melted the tube bottle.  

I picked up one of the big amps from storage tonight and I'll post some pics tomorrow. 

Post removed 

https://app.photobucket.com/u/cdietze21/a/f76242bb-ea49-4235-9994-43003a4bed80

Hello,

Here's a link to some pictures of one of the amps.  The chassis can rotate 90 degrees from the rails for ease of service, and the meter is a handy tube checker  and line voltage monitor. 

I brought the amp up slow on a Variac and it passed sine wave. 

Tubes are:

12AU7

6SN7

4X 6550

6V6

2X OD3

2X 5R4

I brought the amp up slow on a Variac and it passed sine wave. 

That's good! Don't keep running it until the power supply has been refurbished. Otherwise running it is a classic way that a failing filter capacitor causes a power transformer to fail.

 

@cdietze I tried to look at your pics and it says your album is set to private.

Hmm... Sorry about that.  This afternoon was my first experience with Photobucket.  I'll try and straighten that out tomorrow. 

Of course, when I tested the link yesterday it worked because it was me.  I've set it to "public" so please let me know if you can't see them.