Early RTA 12C Sales Document

Sea

I am the original owner of a pair of RTA 12C' purchased early in 1985. I have been looking through the forums and was confused by the distinctions from 12 to 12B and finally to 12C. I was pretty sure mine were 12C's but the PCB on the HF module and the serial numbers on the back both indicate 12B. I was looking through my owner's manuals and found a the attached document stapled to the my receipt. Incidentally, I paid $400 each.

Apparently these are very early 12C's. Notice the reference to Litz Tweeters SL 1000. I think I have read posts identifying SL 1000 as a Peerless tweeter and it would seem that Later 12C's had SL 2000 (Peerless or Litz??). Mine also have a fuse instead of a poly switch.

At any rate, these speakers are still terrific. I recently bought a pair of RTi12's and I do think they are any better. I am starting to consider a cap replacement and maybe a tweeter upgrade for the 12C's

Nightfall

AFAIK the C's have polyswitches only. The early B's are fused and the late B's are polyswitch. SL1000's have a silver plate, Peerless are all black and have a small hole in the middle of the tweeter.

Sea

Based on the document I was given when purchased these are most definitely considered 12C. There are 10 SL 2000 peerless tweeters on the ebay right now for 30 each. is this a decent price? Can I replace the SL 1000's without modifying the CX?

Nightfall

If you have SL1000's and fuses, they are late B's or early C's. There is no difference between the two (late B or early C). There is no such thing as an SL2000 Peerless tweeter, those are two different tweeters. There are SL2000's and there are Peerless. The upgrade for you is the RDO-194's, you have to call Polk CS to buy them. Tell them you are a club Polk member for a discount. Can you post a picture of your RTA12's?

geppy1 wrote:

I have spent a huge amount of time researching this and taking 12s apart. i have three pair right now.There was some throwing whatever was around into the cabinet. I have 12Cs that were made at the same time as my Bs and they have all the same stuff. Go figure. Here it is.

RTA 12
1979-late 1980. Came with stands and had shorter cabinet with tweeter hanging vertical. OUTSIDE DRIVERS ARE NOT ROLLED OFF LIKE LATER ONES.
Tweeeter is HF 1000 marked 7514__ Peerless made in Denmark or 5514 __Peerless made in USA
Drivers are 6500s usually with gray paper trim

RTA12A
I think this when they went to the 6600X driver but I have never seen one

RTA12B
1981-1984 This one is screwy. Full size cabinet, two different crossovers but the only difference seems to be the type of caps used. Same values just different types
Tweeters ,early 1981-83 US made Peerless marked 5514__ Couple of different ones used and THEY DO NOT SOUND THE SAME.. Polk also called them SL1000s. Later (early 84) use the Silver faced real SL1000 Also switched from the pins for tophat location to trees for that. Late 83???
Drivers are 6600X

RTA12C
1984-87
Early 1984-85 Used same crossover and caps as late 12Bs. There are Cs made in early 84 and Bs made after them. All components are the same. Point is a late B is the same as an early C
Tweeters Silver faced SL1000
Drivers usually 6600X but some 6501s late

Late 1986-87 Slightly different caps. Same values but different manufacture. Also now has a Polyswitch in place of the fuse on the top crossover.
Tweeters SL2000
Drivers 6501s

Faustin

I have a pair of RTA 12c's that I purchased last year. They had the SL1000 tweeters in them. I had the crossovers rebuilt and to my understanding there is no difference in the crossover values between the 12b and 12c's other than a fuse on the high frequency or a poly switch. It seems that the Peerless tweeter, the SL1000 and SL2000 worked in all variations of the RTA 12. That being said, if you want to upgrade your tweeters with new, I would suggest the Peerless clones from Midwest Speaker or RDO -194's from Polk. You can also go with used Peerless, and I think the SL 2000 would be the last choice. I have been messing around with used Peerles, the Peerless clones and the RDO-194 tweeters in my 12's to see what sounds the best. At this point I am leaning toward the RDO-194's but am not done comparing. But, of course it is up to your ears.

Nightfall

Faustin wrote: »

I have a pair of RTA 12c's that I purchased last year. They had the SL1000 tweeters in them. I had the crossovers rebuilt and to my understanding there is no difference in the crossover values between the 12b and 12c's other than a fuse on the high frequency or a poly switch. It seems that the Peerless tweeter, the SL1000 and SL2000 worked in all variations of the RTA 12. That being said, if you want to upgrade your tweeters with new, I would suggest the Peerless clones from Midwest Speaker or RDO -194's from Polk. You can also go with used Peerless, and I think the SL 2000 would be the last choice. I have been messing around with used Peerles, the Peerless clones and the RDO-194 tweeters in my 12's to see what sounds the best. At this point I am leaning toward the RDO-194's but am not done comparing. But, of course it is up to your ears.

I'm still waiting on your review of the original Peerless vs the Midwest clone

tophatjohnny

At any rate, these speakers are still terrific. I recently bought a pair of RTi12's and I do think they are any better. I am starting to consider a cap replacement and maybe a tweeter upgrade for the 12C's[/QUOTE]


Confused..... You say you now have the RTi12's and you think they are...or are not any better?? Did you buy the RTi12's new?? If so are they broke in yet?? seems like 2 completely different animals to me. don't know? I do know I'm buying a set of RTi12's here soon, (brand new) and looking for them to give me more bang than my SDA 1 B's!!

drumminman

A cap and resistor upgrade is highly recommended from personal experience. I also rewired my 12C's with single strand OCC teflon insulated wire, put on new Cardas BP's, installed hurricane nuts, new gaskets, & Black Hole 5. They respond really well to this stuff!

FYI, I bought mine new in 1984, paid full retail ($470 each) and the upper boards have RTA 12B printed on them. They also have fuses rather than polyswitches. The owner's manual states that they are C's.

Faustin

Nightfall wrote: »

I'm still waiting on your review of the original Peerless vs the Midwest clone

I have been side tracked working on the SDA 1c's I bought a few weeks ago. Good news is that the 1c's are ready to put back together.

soundfreak1

I have late 12c's upgraded 0194's full recap ( clairty ESA) hurricane nuts wire ect. Well worth it. Do the dynamat as welll.

drumminman

soundfreak1 wrote: »

Do the dynamat as welll.

+1 . . . I knew I forgot to list something

Sea

Yes, the speakers are very different. The RTi's play with more authority and certainly require more power. Are they broke in? Probably not. I would guess they probably have less than 10 hours. I think the RTA 12c's have better imaging and more defined highs. I have them in two different rooms and have not tried driving them with same set-up in the same room for a good A/B comparison.

The newer speakers are running bi-amped with two Carver TFM-35's and a C11 Preamp. The 12's are being Driven by a Carver M1.5t and a Carver C1 Preamp.

Please don't misunderstand, I think both are great speakers. I guess I was expecting more and had really underestimated how really good the 12c's were and are.

HTguru1982

I've owned the RTi10's with CSi5 and FXi3 surrounds. I also have RT55's, CS400i center with RT1000's. Both of these systems were pretty good for movies. I'm now using SDA2's, with Monitor 7C's as my center and surrounds. There is no question in my mind: the vintage Polks are simply better.

For fun, I decided to hook the 55's, 400i, and 1000's back up, and I honestly couldn't listen to them for more than a few minutes. Sure, they have dynamic capability but sorely lack the sound stage, musicality and the ability to "disappear".

Sea wrote: »

Yes, the speakers are very different. The RTi's play with more authority and certainly require more power. Are they broke in? Probably not. I would guess they probably have less than 10 hours. I think the RTA 12c's have better imaging and more defined highs. I have them in two different rooms and have not tried driving them with same set-up in the same room for a good A/B comparison.

The newer speakers are running bi-amped with two Carver TFM-35's and a C11 Preamp. The 12's are being Driven by a Carver M1.5t and a Carver C1 Preamp.

Please don't misunderstand, I think both are great speakers. I guess I was expecting more and had really underestimated how really good the 12c's were and are.

soundfreak1

I love the 12c's since you can biamp, try biamping them with good bass drivers for strong bass attack. Amazing combo (see sig) its the only weekness I see in the 12c's is the bass attack. This combo has produced the most amazing results. I have my external xover set at 1K and above to the polks and 1K and below to the JBL - L123A's simply stunning.

Sea

My RTA 12c's are not set up to bi-amp. I have noticed that the PCB has a place to install binding posts and I have seen instructions that some jumpers are to be removed but I have not done that.