amp to drive R.T.A. 12C?

1ShotBill

I recently acquired a minty pair of R.T.A. 12C speakers as well as a pair of equally nice R.T.A. 11 (or as some call them Monitor 11) loudspeakers. Both have the black Peerless tweeters, as I swapped out the Polk brand silver-faceplated SL-1000's from the 12C's for Peerless. Currently the 12C's are hooked up to our Onkyo A/V receiver (TX-SR607) and they sound much better than any speakers I've ever owned. However, I'm not cranking the volume since this amp is not intended to drive 4 ohm speakers. I don't want to damage our receiver and certainly not these vintage beauties! Although they're currently used as the front speakers in our 5.1 channel system, their main use is in 2ch stereo mode when we listen to vinyl records using a Cambridge Audio phono pre.

My question is... If I want to properly drive just one pair of these speakers (the RTA12C's) using our current A/V receiver, would the addition of a used Hafler 9300 Transnova via the pre outs do the trick? There's also a Carver PM-700 that I'm considering. I believe these power amps are compatible with 4 ohm speakers. The RTA 12C is rated at 4 Ohm and the RTA 11 is rated at 4.5 Ohm. I'm open to other power amp suggestions though. If need be I guess I could possible even consider a completely different pre amp/power amp combo. However, my budget max is $400-$500.

Thanks in advance. I'm new to Polk and very excited to hear the full potential of these beauties!

soundfreak1

If you want to get the rta 12c to thier potiental high currannt and at least 200 w. Or your juat wistleing dixie.

DaveHo

Your Onkyo does not have pre-outs for the front L/R speakers, only zone2 outs. Unless you are using the receiver strictly in stereo mode without a sub-woofer, the zone2 pre-outs are not carrying the same signal as the front L/R, so you can't use an external amp.

12C's & RTA 11's came with the SL2000 tweeter. The Peerless will require a cross-over modification. The backing plates of the tweeters are also different. How did they fit?

That said I used an Adcom GFA-555 when I had 12C's with good success. I don't have any experience with the amps you mention.

-Dave

erniejade

I think the carver amp you listed is a pro amp yes?

1ShotBill

Thanks for your advice!

It's my understanding that the R.T.A. 11 only came with the peerless tweeters (at least that is what a Polk rep recently told me). My R.T.A. 12C's came with the silver-faced SL-1000 tweets, which I was told were never used. The speaker cabinets and tweeters came with their original 3 boxes. The SL-1000's were mounted on the crossover modules. The high-hat/grills were in the same box. These peerless tweeters I bought (originally from a pair of Monitor 7's) lined up perfectly with the screw holes and everything. When I asked a Polk rep about the SL-1000 on a 12C he told me that early versions of that speaker came with the older SL-1000. Polk has apparently been known to do this.

I hope that's helpful.

jon s

I used a 100-watt Marantz PM7200 amp to drive my RTA12cs and they sounded fine... But when I swapped it out with a Acurus DIA-100 (also a 100-watter, but with a bigger power supply with more current), the Polks really came alive. The problem was the Marantz had a tightly regulated power supply which constrained the output and the Acurus did not, the caps and transformer in the Acurus was a lot bigger than the paltry ones in the Marantz.

Moral, it's not really the wattage, it's the current.. You want the speaker to sound great, get a high powered amp with a LOT of current, e.g. a big (and heavy) power supply.

1ShotBill

I have the R.T.A. 11 (or as some call them, Model 11) speaker. Not the 'T' or 'TL' models. They have a 12" PR below the mids and black-domed Peerless tweeters. I believe there are several threads on this comparison already.

Here's a PDF of the R.T.A. 11/Model 11 speaker I'm referring to: http://www.polksda.com/pdfs/Model11Manual.pdf

And a photo of my Model 11/R.T.A. 11:

DaveHo

Rta 11 & monitor 11 are different animals, hence the confusion. Fact remains,your receiver, unfortunately isn't able to use an external amp in your current configuration.

1ShotBill

yes... I meant to say I had "Model" 11, not Monitor 11 speakers. My bad.

Thanks again for pointing out that I don't have normal pre-outs on my A/V receiver. I was very close to buying a power amp that would have been useless with my current rig.

1ShotBill

I'm seriously considering an Acurus DIA-100 now. The reviews I'm reading sound great! I think the punchy lows and slightly emphasized mid-treble would sound good with my RTA 12C's with the peerless tweeters. Sounds like you think it's got enough juice to drive the RTA 12C's at 4 Ohms properly, right? Seems like a lot of people recommend 200wpc minimum for these, although I hear what your saying about the current.

I think we I may end up doing is using an Acurus DIA-100 with our Cambridge Audio phono pre to play records and just drive our 12C's in a pure stereo system. Then for watching BluRays in 5.1 surround I'll throw Polk Monitor 5A's on the Onkyo as the main L & R speakers. I think they are okay at around 6ohm. (I'm currently trying to nail down their ohm rating.) Not as clean looking of a set up to have RTA 12C's right next to the Monitor 5A's in our living room, but that may have to do for now.

Thanks again Jon!

rscamer

Hey try and find some old Carver tfm-45/42 amps they go for a reasonable price and would make those 12C's sound great. I went from a tfm-35 to a tfm-42 and noticed a difference. I say the more power the better with the 12C.

1ShotBill

Still haven't pulled the trigger on an amp yet. Now I'm considering something like a NAD 1700pre with a 2400 or 2700 power amp. Or maybe a NAD 7250PE or C 325BEE with a power amp. Thoughts on these? I do already have a solid separate phono pre, so the absence of that input on the NAD C 325BEE isn't a problem.

1ShotBill

Yesterday I pulled the trigger on an NAD 2400 THX power amp and will soon try to obtain a NAD 1130 pre amp that I have my eyes on. The 2400 provides 100wpc at 8Ohm, so it should have plenty of juice to drive my 4Ohm RTA 12C speakers considering the 5.7db of headroom the amp is reported to have. I'll keep you posted on what I get in terms of a pre amp and how the setup sounds when I connect them to the secondhand Rega P25 turntable I just snagged.