RTA 12 which model are these?

gudnoyez

http://quadcities.craigslist.org/ele/4085327589.html

How would one tell if these are A,B,C, and is there that many series, and do these have the peerless tweeter? How do these sound compared to Crs+s or 2b's and do these appear to be priced right for the shape they are in?

Nightfall

Late B or C. Not Peerless, SL2000. They appear to be in great shape, pictures can be deceiving though, the lighting isn't the best. Price IMO is a little high. I paid $225 for my pair with Peerless tweeters.

I haven't heard all three pairs but from what I have read, they compare favorably.

gudnoyez

I figured they were priced to high I was just wondering what series they were, if they would of had the peerless tweeters I would of wanted to give these a listen and compare them to my SDA's. I have to many speakers anyways. I will always be curious on how these sound. Thanks for your reply.

boston1450

Those look darn nice though. If someone talks them down a hair they are getting a nice set of speakers & the hats look nice also

zingo

They do look in great condition, and even with some paperwork!

drumminman

Those are 12C's, probably around 1985. They do look to be in good shape.

As far as comparing them to SDA's, my modded C's can't do what my 2.3TL's do, but they are fine speakers in their own right. They throw a great soundstage with a solid center image. Nicely balanced throughout the frequency range and smooth.

Nightfall

drumminman wrote: »

Those are 12C's, probably around 1985. They do look to be in good shape.

As far as comparing them to SDA's, my modded C's can't do what my 2.3TL's do, but they are fine speakers in their own right. They throw a great soundstage with a solid center image. Nicely balanced throughout the frequency range and smooth.

He was asking about comparing them to 2B's.

Late RTA-12B's had SL2000 as well.

drumminman

Nightfall wrote: »

He was asking about comparing them to 2B's.

Late RTA-12B's had SL2000 as well.

Or to CRS+, both of which I took to mean he was interested, in general, in how they image compared with SDA's.

Polk famously threw whatever parts they had on hand into some of their speakers. My 12C's came with SL1000's.

Nightfall

drumminman wrote: »

Polk famously threw whatever parts they had on hand into some of their speakers. My 12C's came with SL1000's.

No doubt, especially the RTA12's from what I've read. Did you upgrade them to RDO's?

So it really is hard to say if a pair is A/B/C then huh? Not sure why it would really matter, just find a pair with the tweeter you want, really.

gudnoyez

So is it safe to assume these shown are the the ones that would benefit from RDO's while the later ones were with the peerless? So the ones listed is a former model considered a series A?

Nightfall

It's confusing.

The ones you listed are definitely not A.

gudnoyez

So these ones shown are not 2 way and have the SL2000 so these ones would be the better model with an upgrade to RDO 194's compared to the original 2 way with peerless? The crossovers were they all located on top like these ones on all series of the RTA 12's?

Nightfall

gudnoyez wrote: »

So these ones shown are not 2 way and have the SL2000 so these ones would be the better model with an upgrade to RDO 194's compared to the original 2 way with peerless? The crossovers were they all located on top like these ones on all series of the RTA 12's?

But not all Peerless are 2 ways. My pair are Peerless and have 2 crossovers and are labeled left and right.

All RTA12s have a crossover on top. Only the early ones have a crossover ALSO inside the cabinet.

drumminman

The RTA 12's (first in the series) were not designated as A, they were just RTA 12. The later versions (B's & C's) were two way speakers. However, for imaging purposes one of the MW's played a narrower part of the frequency spectrum, whereas the other covered that and more. From my understanding this had to do with imaging.

Interesting experiment to test the above is to put the speakers on opposite sides, i.e. L on R etc. The imaging collapses and they sound terrible. Ask me how I know ;^)

Mystery

They look just like my RTA-12C's. I sold them for $225.



From my online research, RTA-12C's are the best in RTA series and they are the only ones that are really time aligned but 12B's may also have same feature from the linked document below.

All other RTA series including original RTA-12 mimic that name but they are not mirror imaged and not truly time aligned.
RTA-12C's actually are mirror imaged and have different different crossovers for left and right speakers/mid-woofers unlike other RTA's that have single crossover.
http://www.polksda.com/pdfs/1985Sales.pdf
It mentions RTA-12C uses unique technology for imaging and clarity that was not in other models.
It handles up to 500 watts of power.
It utilizes phase-coherent open air driver mounting in a mirror imaged, fullsize floor-standing configuration.
This model won the AudioVideo Grand Prix Speaker of the Year Award and was selected for the prestigious CES Design and Engineering Exhibition as one of the industry's most innovative products.

However, it's only true on the B and C versions where outside mid woofers drive 60-600HZ and inside mid woofers drive 60-2000HZ.
This applies to RTA 12Bs and Cs.

--> The early RTA 12 (the ones without B or C) DO NOT roll off the outside driver and are not mirror imaged. They have only one crossover.

DaveHo

The picture of the Xover isn't the best, but I think I see a polyswitch instead of a fuse for tweeter protection, which would make those 12C's.

drumminman

Not necessarily - my 12C's have fuses, and the two 12B schematics in the sticky's show both a fuse (original) and a polyswitch (revised). It can get confusing.

I think you need at least two corroborating features for certain identification, lol. Though I think most RTA 12_ territory has been covered in this thread you can do a search for posts by geppy1. He's the resident expert for this top of the line in the monitor series.

Nightfall

I think I have the best model. Peerless, fused, imaged. Next best would be SL2000, fused imaged.

drumminman

Nightfall wrote: »

I think I have the best model. Peerless, fused, imaged. Next best would be SL2000, fused imaged.

Au contraire, the best of the series is modded (sonicaps/mills in both upper and lower Xovers, internal wire replaced with Teflon OCC copper solid core wire, strips of Black Hole 5 behind MW's, MW baskets dynamatted, Hurricane nuts) fused, 12C's.


;^)

Nightfall

drumminman wrote: »

Au contraire, the best of the series is modded (sonicaps/mills in both upper and lower Xovers, internal wire replaced with Teflon OCC copper solid core wire, strips of Black Hole 5 behind MW's, MW baskets dynamatted, Hurricane nuts) fused, 12C's.


;^)

Did you replace the SL2000's with RDO-194's? That (yours) is a pair of RTA-12's I would really like to hear.

Mr. Bubbles

reading through this thread got me to wondering about differences in these models. i went to the sticky's to find the schematics and noticed that there is no schematic for the 12C, but there are 2 for the 12B with the only difference between those being a fuse or a polyswitch. Does anyone have a schematic for the 12C? What are the differences between the 12C and the 12B.also the schematics do not describe the driver compliment for the 12's and the 12B schematics do not indicate tweeter part #'s. I can easily see a difference in the HF circuit between the 12 and the 12B and assume this is due to the differences in the Peerless and the SL2000/1000 or whatever other tweeter they used. But if they subbed tweets between these two this may not be a correct assumption and the circuit change may have simply been a model upgrade without concern for the actual tweeter used (though this would no seem to be probable, I am not sure how close the SL and the Peerless tweeters are electrically for this model).

Anyway I was just wanting to study the differences in more detail but the schematics leave a good bit to be desired in this case. Can anyone help?

Mr. Bubbles

On another note it may not hurt to contact the seller about these and other gear that may be for sale. There are several other pairs of speakers on and under the work bench as well as a shelf full of vinyl with other vintage gear including a turntable and what appears to be at least one Marantz piece.

Nightfall

Mr. Bubbles wrote: »

also the schematics do not describe the driver compliment for the 12's and the 12B schematics do not indicate tweeter part #'s.

I can tell you my pair are 12B's with Peerless and MW6600X's

drumminman

Mr. Bubbles wrote: »

reading through this thread got me to wondering about differences in these models. i went to the sticky's to find the schematics and noticed that there is no schematic for the 12C, but there are 2 for the 12B with the only difference between those being a fuse or a polyswitch. Does anyone have a schematic for the 12C? What are the differences between the 12C and the 12B.also the schematics do not describe the driver compliment for the 12's and the 12B schematics do not indicate tweeter part #'s. I can easily see a difference in the HF circuit between the 12 and the 12B and assume this is due to the differences in the Peerless and the SL2000/1000 or whatever other tweeter they used. But if they subbed tweets between these two this may not be a correct assumption and the circuit change may have simply been a model upgrade without concern for the actual tweeter used (though this would no seem to be probable, I am not sure how close the SL and the Peerless tweeters are electrically for this model).

Anyway I was just wanting to study the differences in more detail but the schematics leave a good bit to be desired in this case. Can anyone help?

The Xovers on my 12C's follow the schematics with the fuse for the 12B's . The tweeters are SL1000's and the MW's are MW6600X. Mystery does a good job detailing the differences between the various models in post #17 so I won't repeat those here.

Nightfall I still have the SL1000's installed that came with the speakers. I'm usually very sensitive to harshness in the high frequencies, but I don't hear it with these. Perhaps the Sonicaps/mills tamed them. I may still get some RD0-194's though as they're universally well thought of here. If you ever find yourself out this way give me a call and you can get your ears on these.

Mr. Bubbles

drumminman wrote: »

The Xovers on my 12C's follow the schematics with the fuse for the 12B's . The tweeters are SL1000's and the MW's are MW6600X. Mystery does a good job detailing the differences between the various models in post #17 so I won't repeat those here.

Thanks for the reply. However I am still somewhat confused as to the differences. Per this thread the 12's in the original configuration as well as the B's and C's used 3 different tweets; the peerless, the SL2000, and the SL1000. With posts here indicating Peerless for the originals, either Peerless or SL2000 for the B's, and either 2000's or 1000's for the C's (I think I got that right per the above posts). The C crossovers appear the same as the B crossovers (at least in yours). and the B's and C's used the same MW's.

Now to look at post 17 by Mystery. ( I apologize, I haven't exactly figured out the multi-qoute feature so I copied and pasted)
I have interspersed my comments with his.

All other RTA series including original RTA-12 mimic that name but they are not mirror imaged and not truly time aligned.
(speaking only of the time alignment here) Except the other 12's; the time alignment is due to the physical orientation of the tweeter. Specific not just to the RTA 12C's but all RTA 12 versions. The mirror imaging is used in BOTH the 12B and 12C.

RTA-12C's actually are mirror imaged and have different different crossovers for left and right speakers/mid-woofers unlike other RTA's that have single crossover.
Got it but still apparently the same as the 12B.


http://www.polksda.com/pdfs/1985Sales.pdf
It mentions RTA-12C uses unique technology for imaging and clarity that was not in other models.
This doesn't say what other models. With the B and C using the same apparent crossover it would seem this doesn't mean all other RTA's.

It handles up to 500 watts of power.
Check.

It utilizes phase-coherent open air driver mounting in a mirror imaged, fullsize floor-standing configuration.
Same as the B best I can determine.

This model won the AudioVideo Grand Prix Speaker of the Year Award and was selected for the prestigious CES Design and Engineering Exhibition as one of the industry's most innovative products.

However, it's only true on the B and C versions where outside mid woofers drive 60-600HZ and inside mid woofers drive 60-2000HZ.
This applies to RTA 12Bs and Cs.

With the information given here and what i have been able to find There should be little to no difference between the 12B and the 12 C. However that cannot be correct due to the actual model designation change there would have been a change to the speaker. I still don't know the driver compliment of the original 12's. This still leaves me wondering exactly what was changed between the 12's and the B's and then what was changed between the B's and the C's.

drumminman

Mr. Bubbles wrote: »

With the information given here and what i have been able to find There should be little to no difference between the 12B and the 12 C. However that cannot be correct due to the actual model designation change there would have been a change to the speaker. I still don't know the driver compliment of the original 12's. This still leaves me wondering exactly what was changed between the 12's and the B's and then what was changed between the B's and the C's.

As far as I know the B's and C's use the same Xover. There are C's using the SL1000 tweeter and the SL2000 tweeter. There are B's using the both as well. Perhaps the C's were designated as such because they used the later (going by model #) MW, the 6600X c/w the 6501. So why designate a seemingly later iteration as C when it used some components of an earlier model? Don't know, other than it's one of Polk's idiosyncracies.

BTW, the Xover for the C's is not different for left and right speakers, it's the same, based on what I see in the schematics and my experience in rebuilding it. It's confusing.

Mr. Bubbles

I guess it could be a driver update issue. I know some earlier driver were essentially the same as later drivers except earlier units used round wire in the voice coils vs square/flat in the later versions. Could be as simple as that possibly. it would be nice to know if the original 12's could easily be upgraded to either a B or C (crossovers come up pretty often on the bay) easily or if the peerless tweet could be swapped in to later versions, if it is electrically a match to the crossover.

geppy1

Here is the way the RTA 12 story went. Remember this is a screwy series and sometimes what was on the shelf went into the speaker

RTA12s 1979-1980 6500 drivers with Peerless from Denmark
Short cabinet on stands NO rolled off drivers and one croosover on top with fuse

RTA12B 1981 -early 1984 6600X drivers with Peerless
Tall cabinet with rolled off outer drivers and two crossovers with fuse

RTA12B Late 1983 early 1984 6600x drivers SL 1000
Tall cabinet with rolled off outer drivers and two crossovers with fuse Started to use treelocks instead of pins for the hat

RTA 12C Early 1984-mid 1985 6600x with SL 1000
Tall cabinet with rolled off outer drivers and two crossovers with fuse

RTA12C Mid 1985-1987 6501 drivers with SL 2000
Tall cabinet with rolled off outer drivers and two crossovers with poly switch

NOTES
1) I think the early 12C won a Hi Fi Grand Prix Award

2) The crossover from 1981-87 RTA 12B and RTA 12C is the same with the exception of the fuse being replaced with a polyswitch and resistor. Thery did use different types/brands of caps but the values stayed the same.

3) There are late RTA 12Bs that have a higher serial number (on back) then early RTA 12Cs and the speakers are identical.
Early 1984 is where this occured (18,000-19,000 ish Early 1984 is a mess

4) The Polk speaker replacement chart is not always right

5) My favorite, From 1981 to late 1983 no less then 3 different Peerless tweeters were used (same xover( and they all sound different.

drumminman

Thanks for chiming in G1. I'll have to hang onto this info.

Hey Bubbles, G1 has RTA 12B Xovers for sale in the flea market as I write this.

Mr. Bubbles

geppy1 wrote: »

Here is the way the RTA 12 story went. Remember this is a screwy series and sometimes what was on the shelf went into the speaker

RTA12s 1979-1980 6500 drivers with Peerless from Denmark
Short cabinet on stands NO rolled off drivers and one croosover on top with fuse

RTA12B 1981 -early 1984 6600X drivers with Peerless
Tall cabinet with rolled off outer drivers and two crossovers with fuse

RTA12B Late 1983 early 1984 6600x drivers SL 1000
Tall cabinet with rolled off outer drivers and two crossovers with fuse Started to use treelocks instead of pins for the hat

RTA 12C Early 1984-mid 1985 6600x with SL 1000
Tall cabinet with rolled off outer drivers and two crossovers with fuse

RTA12C Mid 1985-1987 6501 drivers with SL 2000
Tall cabinet with rolled off outer drivers and two crossovers with poly switch

NOTES
1) I think the early 12C won a Hi Fi Grand Prix Award

2) The crossover from 1981-87 RTA 12B and RTA 12C is the same with the exception of the fuse being replaced with a polyswitch and resistor. Thery did use different types/brands of caps but the values stayed the same.

3) There are late RTA 12Bs that have a higher serial number (on back) then early RTA 12Cs and the speakers are identical.
Early 1984 is where this occured (18,000-19,000 ish Early 1984 is a mess

4) The Polk speaker replacement chart is not always right

5) My favorite, From 1981 to late 1983 no less then 3 different Peerless tweeters were used (same xover( and they all sound different.

Thanks,

I thought that may have been your x-overs on the Bay. This helps a good bit. Looks like it would be ptretty easy to upgrade the originals by replacing the x-over from a B or C. wouldn't seem like driver replacement would be necessary for this since the same basic crossover used roughly 5 different tweets and a couple to 3 different MW's. it would seem that all the driver were electrically very similar, at least as a match to the crossover.

geppy1

You are not going to believe this. I am changing/ redoing mine and today I received a whole set of parts from original 12Cs ANOTHER VARIATION I have never seen this I am reviewing this and checking parts dates but mid 19,000 with SL 2000s 6501s and a fuse REALLY it appears real. FYI polk often seems to have made xovers months ahead of time on RTA 12s and then had them sitting