Polk RTA-11 (Monitor not Tower) up and running thanks to Michael8it!

Shacky

Thansk to Michael8it I obtained a replacement MW6600 driver to replace the one frozen in my new to me pair of RTA-11's. Wow!!! Playing them with my Adcom CTP-500II using my Sansui 890DB as Amp for now. I like the contour the Adcom has for low level listening. Uses the later HArvard curve which does not increase treble like Fletcher-Munson.

Have only had about an hour to listen. Very open and airy sounding. Nice bass though not as powerful as my AR 3a's. Upper end is not contest.

These are the rarer non-towers. I plan to do a full recap and I'd like to veneer the cabs - that vinyl is butt ugly.

Will also look into Dynamat treatment Mike suggested.

Shacky

Oh almost forgot. How do you tell right from left with these speakers? Mine have no marks on the back. But I notice the terminals are reveresed - red/black and black red on other. I have them with both red posts facing outward. 50/50 chance I have them correct.

Can anyone confirm or do I need to look inside to make sure?

mdaudioguy

Nice... However, I just checked mine and they have stickers indicating "Left Channel" and "Right Channel". The terminals are the same on both, however - red on left, black on right. I guess that doesn't help much...
Jesse (F1nut) might know something about this.

F1nut

my new to me pair of RTA-11's.

Those are Monitor 11's, not RTA.

Nice bass though not as powerful as my AR 3a's.

You should check for air leaks as the bass should surpass the AR 3a's.

How do you tell right from left with these speakers? Mine have no marks on the back. But I notice the terminals are reveresed - red/black and black red on other.

I'll try to remember to look the next time I see them, but I think Ed is right that the terminals are the same on both. Could also be why your bass isn't up to snuff.

One thing you can check right now, the left speaker will have some Sonex foam behind the right mid-driver only and the right speaker will have it behind the left mid-driver.

Shacky

I thought about the variation in terminals being due to someone messing with them. Though I reversed polarity on one to check and bass was not as good.

They seem to be air tight as when I depress midrange I see immediate effect on the PR.

And you just solved my problem. The driver I replaced was on left and had folded foam (Dark grey) behind it. So that must be the right speaker - which is now in left position :redface:

Shacky

F1nut wrote: »

You should check for air leaks as the bass should surpass the AR 3a's.

You sure about that? I've never heard a speaker with better/more accurate bass performance than my AR's. I do feel the Polks are tilted up - which just about any speaker is versus AR of that era.

The Polks may reproduce bass as low in freg as AR's but I'm doubting the can mach overall bass performance - unless I do have serious air leak or polarity problem.

Does anyone have the Monitor 11 schematic?

Shacky

Here's what the owners manual says:

Model 11 Real-Time Array
Reference Monitor Series (R.T.A. 11)

F1nut

They seem to be air tight as when I depress midrange I see immediate effect on the PR.

No, you want to press in and hold the PR while watching the mid-drivers. They should slowly recede and come to rest in 2 or 3 seconds.

You sure about that?

Fairly. I think the Monitor 11's produce a lot of bass. I use to have AR 3's, but it's been a long time.

Does anyone have the Monitor 11 schematic?

Should be listed in the schematic sticky. Otherwise, I have them.

Here's what the owners manual says:

Yeah I know, I have one too. Forget all that, they are Monitor 11's.

Shacky

Thanks F1nut! They aren't so good on old Beatles Mono stuff but boy do they come alive when there is quality bass in recording. Playing King Crimson Thrak. Never heard this much detail. Bass lines very musical and I think would compete with AR's except in total output. Different balance bottom to top.

These are quality speakers for sure :biggrin:

mdaudioguy

Yes, I think they are some real gems! What are you powering them with?

Shacky

Think I might have messed up. I connected the white wire to the left side mid driver positive terminal and black to ground, The white wire had dual wires attached so now I'm realizing that would more likely be ground.

In schematic looks like black wire is positive to driver 1.

Oh boy - that means I may have one mid/bass out of phase and I will get more bass when corrected :idea:

Shacky

Using my Sansui 890DB (Euro 8080DB) as amp right now. 85 WPC. Adcom tuner preamp 500 II.

Shacky

OK I corrected the driver phasing. Then I figured the alternate pos/neg binding post is likely from PO misplacing the plastic binding post screws.

No more reticent bass :biggrin:

Playing A Hard Days Night - now I'm in bliss. Sounded so thin earlier.

Thanks guys!!!!

Shacky

Late night playing the new to me Polks. Tried some more test tracks. Acoustic Alchemy Angel of the South, Spyro Gyra River Between, Micheal Franks A Walk In The Rain and Nightmoves.

Gorgeous. Just gorgeous!!!!

F1nut

There ya go.

Shacky

Now playing Buddy Guy and Ronnie Earl. Still lovin' them.

Shacky

Had more time tonight to get familiar with these lovely Polks. I was a big http://nigelshaw.smugmug.com/Other/Easter-2012/22339950_7LTdLK#!i=1785080123&k=QVjCbmgolk fan in the 90's. First purchase was Monitor 4's originally bought for kitchen but stayed in living room till I bought RM 3000's. Never really had right power for the RM's till I got into Vintage. They are now in my wife's studio with my Pioneer SX-950 (recapped) sounding great.

So far I'm loving the Monitor 11's. I did the PR push test F1nut recommended. The woofers go back right away. No 2 second delay. Where do air leaks typically sneak up?

Schematic doesn't have cap values. Anyone know sizes I need to order? I have some nice Russian PIO bypass caps I can incorporate. Ultimately I'd like to put veneer on these. Have never done that before.

F1nut

Where do air leaks typically sneak up?

The cabinet seams are one area, but Polk used a lot of glue inside the Monitor 11's, so that's probably not a concern. The driver/PR/tweeter gaskets would be the first thing I would check. Make sure the gaskets are in good conditon and that all the screws are tight.

Schematic doesn't have cap values.

There's a second schematic in the sticky with that info.

I have some nice Russian PIO bypass caps I can incorporate.

Bypass caps are nasty. Instead, I'd suggest changing the stock caps to film/foil and the resistors to Mills 12 watt.

Shacky

Thanks F1. Found it. Those 45 uF new caps could get pretty big. Anybody found one that fits well? Will take you advice on the Mills resistors.

So why do you say bypass caps are nasty? I've used Russian military grade PIO 0.047 parallel with tweeters in JBL, AR's, EPI, and Dynaco's with great results in past.

Shacky

EPI 202 example

F1nut

If you're bypassing electrolytic's one might argue that there may be some benefit, but film/foil caps don't need bypassing and when they are, the bypass cap imparts artifacts. At first, it can sound of neat, but later becomes annoying as hell.

Shacky

OK - respect your opinion. I was using them with Daytons - 5% in above example and 1% elsewhere. I know JBL touted the practice. Once I bought a box of them it was typical I am a hammer so every problem looks like a nail situation.

They did work nnice in my Eico HF-81 for sure.

Shacky

Hooked them up to my Eico HF-81 tube int amp again. Now that phase issue resolved they do sound quite nice with slight loss of bass edge I'll call it compared to my Adcom Pre - Sui Amp SS setup.

Boy they sound nice and warm with tubes.

Anybody know what their efficiency is?

Shacky

Shacky wrote: »

I did the PR push test F1nut recommended. The woofers go back right away. No 2 second delay. Where do air leaks typically sneak up?

Ooops - I was pushing PR and releasing. Will have to redo after checking instructions second time. :redface:

F1nut

Shacky wrote: »

OK - respect your opinion. I was using them with Daytons - 5% in above example and 1% elsewhere. I know JBL touted the practice. Once I bought a box of them it was typical I am a hammer so every problem looks like a nail situation.

They did work nnice in my Eico HF-81 for sure.

I came to the conclusion that bypass caps are nasty a while back. Sometime after that I came across the following, which describes better than I can, exactly the conclusion I came to.

So why use a bypass at all? There are actually components of very high frequencies in some audio waveforms. Some are high order harmonics. If you think of a square wave, the right angles at the top of the wave are extremely high in frequency. Sometimes there are high frequency components in very fast audio sounds, for example, the instantaneous tap of a drum stick on a cymbal. These are the sounds that should be "helped" by including a small-value bypass capacitor in a high pass crossover.

Well, I don't think so. If the 8 ?F capacitor blocks frequencies below 5000 Hz and passes frequencies above 5000 Hz, why do we need what is actually another crossover for the same tweeter, but operating at frequencies already passed by the big cap? I am sure engineers have a very good reason, and a couple of them have tried to educate me on this subject. I respect the science and electrical theory on this subject, and my technical background helps me to understand it fairly well. But there is one small problem: the bypasses all sound bad!They add a quality that at first sounds like an increase in air and detail, but after a couple of hours becomes an intrusive harshness and discontinuity in the upper treble. Remove the bypass: all of the detail is present but without that grating and annoying sound. The high frequencies are cleaner, smoother, and much more enjoyable. It doesn't matter if the bypass cap is Teflon?, polystyrene, or common polypropylene, the results are very similar. And to be avoided.

Michael8it

Thanks for 'props' ! Hope you enjoy them!

Shacky

Fi

Thanks for that bypass quote. All the speakers I've bypassed to date were 60's-70's vintage and probably not capable of reproducing much in the ultra high range - nor are my 56 year old ears capable of hearing them. I can now only hear the crickets at the begining of Sun King on Abbey Road with headphones. And it pisses me off as I know they are there! I hear them on the outgoing previous song at least ; )

I had read that using a high quality bypass cap in conjunction with a lower quality cap makes the combination more like high quality overall. The caps I used are PIO - not film or poly. It's a controversial area for sure with physics way above my head.

Since these Polks have excellent high range I will likely stay away from bypassing and use quality caps to start with. The 45's will have to do with something a little lower on the price scale.

I had good results with Sonicaps on my Klipsch Fortes.

Shacky

I did the air leak test. They are air tight. Mids hardly go back when pressing PR. So I guess bass output is were it should/can be.

I read elsewhere that many feel large gauge air core inductors enhance bass. Anyone here try that?

1ShotBill

I would also like to know that their efficiency is. I don't see anything in the Model 11 (R.T.A. 11) manual showing the dB rating unfortunately. My guess would be around 92dB, but I'm no expert.

F1nut

Since they are basically Monitor 10's on steroids I'd say they are probably the same efficiency.