RTi12 Rehab help - muddy woofers, tin-can mids. Why?

ab_ba

Hello, I'm new here.

I picked up a pair of RTi12's on craigslist for a great price, knowing they'd need some TLC. When I hooked them up, they sounded lousy. No surprise there. I took out all the drivers, and hooked each up individually to my receiver's speaker outs. I ran test tones through them. I found two woofers were blown (they rattled) and one tweeter (no sound at all). The four other woofers all sounded good, and they were reasonably matched for volume (within about 1dB). All four mids were fine. I put three of the good woofers, two mids, and the one good tweeter into the same tower, and bi-amped them from my 7.1 Yamaha RX-V675 (~110 wpc, depending who you ask).

I expected to hear a single channel of pure goodness, but I got a muddy tin can. What went wrong? The woofers sounded muddy. They were very quiet - even when I disconnected the speaker cable from the upper posts, and cranked the volume, they didn't get much louder, and the sound quality was terrible. All three woofers together were quieter than a single woofer hooked directly to the receiver. I didn't realize the crossover worked in series - I needed to plug in all three woofers before any sound came out. As for the mids, they sound as if the music was being played inside a tin can. In all, the RTi12's are sounding far worse than my TSx330's.

I'm going to order some replacement parts, but what do I need? Is this a bad crossover? Is it possible for a woofer to be bad somehow even if it sounds fine on its own? How can a crossover go bad anyway? What on earth did the previous owner do? Could driving it from an under-powered amp with the volume cranked up ruin a crossover somehow? Other than a bad crossover and bad woofers, is there anything else it could be??

Any input or suggestions will be most appreciated.

F1nut

Seems like you've got a mess and that you don't really know what you're doing. Start by making sure you have the right wires going to the right drivers.

I took out all the drivers, and hooked each up individually to my receiver's speaker outs. I ran test tones through them.

That was not a good idea.

and bi-amped them from my 7.1 Yamaha RX-V675

You didn't bi-amp squat.

nguyendot

Call support tomorrow and see if they can help you sort some of it out. If you need spare parts..they have them.

ab_ba

Thanks F1nut and nguyendot. I will definitely call support this morning. F1nut, it seems like you know more than you're conveying. Would you mind telling me - what's wrong with hooking up a driver to a speaker? The crossover is just a passive filter, right? As long as I keep the volume low and the pitches within the driver's range, why is this bad?

And, as far as bi-amping, the receiver has two channels (6&7) that can either be used for "surround presence" or re-programmed to bi-amp the two mains. It's true that it doesn't let me set passbands for each speaker channel, but the crossover does that anyway. So if this isn't bi-amping, what is? Thanks again.

F1nut

As long as I keep the volume low and the pitches within the driver's range, why is this bad?

I didn't say it was bad, I said it wasn't a good idea. However, now that you have explained how you did it no harm should have occured.

And, as far as bi-amping, the receiver has two channels (6&7) that can either be used for "surround presence" or re-programmed to bi-amp the two mains. It's true that it doesn't let me set passbands for each speaker channel, but the crossover does that anyway.

You answered your question, sort of. You are still sending a full signal and therefore wasting a lot of the available power. Speaking of which, by using all the channels of your 110wpc (2 channels driven) AVR the actual wpc will have dropped like a stone and could be as little as 50wpc.

So if this isn't bi-amping, what is?

Pure hype.


Have you checked the wiring yet?

pitdogg2

Double check that you have it wired correctly, Then look at the crossover could have some fried resistor's or worse.

You are finding out what happens when you use a receiver to power a speaker that needs gob's and gob's of good CLEAN power with current something that no receivers (not many) have. That "Bi-amping" is pure hype most muti-channel receivers drop way off with the more channels driven so basically you just CUT the amount of power going to it instead of upping

ab_ba

Thanks again F1nut and pitdogg2.

Yup, you are right - bi-amping with a consumer-grade receiver is cowturd. It's shameful they even advertise it. I called Yamaha - I had to hear it direct from them. After listening to some hold music, I got tech support. He had to put me on hold to "go look something up", then he came back with some marketing babble about about bi-amping. I asked, "when you bi-amp does the speaker receive double the wattage?" The answer to that was "um, no." OK thank you. I went back over the manual and the spec sheets - there's nothing about that in their literature. I thought I was buying a box with seven 100W amps in it, but it's nothing like that. It's more like a 180 W amp, then you divide that down by the number of speakers you hook up. Truth in advertising, eh?

I'm reluctant to shell out $1600 for an Emotiva pre/pro and power amp. (I asked the Yamaha guy how much it would cost me to get a unit of theirs with a true 200 W per channel. It'd be around 2000 bucks.) But, it stinks if I can't use my speakers at all without a major expenditure. I called Polk and ordered three woofers and a crossover. I'll see how it sounds with those. If I still have problems, then yup, it's the amount of power I'm supplying, and I've got to bite the bullet.

Regarding the wiring, I don't see any way I could have messed that up. The clips are different sizes, so they only fit one way onto the woofer's terminals. The woofers are all the same, so there's no possibility for a mess-up there.

F1nut

I'm reluctant to shell out $1600 for an Emotiva pre/pro and power amp.

If your AVR has pre outs all you need is a power amp and less than $1600 will get you better sound than that stuff.

(I asked the Yamaha guy how much it would cost me to get a unit of theirs with a true 200 W per channel. It'd be around 2000 bucks.)

I'm 99.9% sure that Yamaha doesn't have an AVR with that amount of power. In fact, I'm not aware of any AVR that is capable of 200wpc.

But, it stinks if I can't use my speakers at all without a major expenditure.

Bottom line, to perform properly those speakers require more power than an AVR can provide.

Regarding the wiring, I don't see any way I could have messed that up. The clips are different sizes, so they only fit one way onto the woofer's terminals. The woofers are all the same, so there's no possibility for a mess-up there.

I can't find the schematic for those speakers, but it's entirely possible that each woofer has a specific pair of wires coming off the crossover, not that you had the polarity wrong.

thsmith

WHat F1 said, I recently picked up a Carver TFm-45 that had been fully serviced 12 months earlier. I picked it up for 3 bills, While this amp is not everyones cup of tea it is a high current amp and will make those RTi12s sing if the crossovers are not fried.

This is just one example and if your AVR has preouts you are set.

ab_ba

My speakers sound really good now! The parts came in from Polk on Friday. Two crossovers, two woofers, one tweeter. The main problem was the crossovers - when I got the old ones out there were what looked like scorch marks on them. Amazing. Must have been quite a party that night. It’s clear that the previous owner must have had them hooked up to a cheap amp, and just cranked them. I picture smoke pouring out of them just when they died. There were two clearly-fried woofers and a tweeter. The other drivers sounded fine on their own, so I think I can trust them to be fully usable.

Now the 12's sound really nice. I have them running off my old Marantz SR8200 (120 Wpc), which is being driven by the pre-outs on my Yamaha. They sound clear and detailed (that “forward” sound I read about), but they also were clearly lacking oomph. So today I bit the bullet and called Emotiva to order an XPA-5 and a UMC-200. I think that should do the trick. I’ll report back if the sound is any different from my Yamaha I realize I could cruise around on ebay, usaudiomart, etc, for a good used amp, but at this point I am ready to stop tinkering and just listen to some music. Besides, a used XPA-5 is not all that much cheaper than a new one…

The install was remarkably straightforward - no ambiguity about the clips or what goes where. Polk designs their stuff to be used for years, not just tossed out after five years. I took out all the drivers and the fiberglass inside. I freed the wires from the putty sealing the box for the mids and tweeter. I fed everything back in - the cable lengths make it easy to tell what goes where. I re-sealed the putty to close up the mid box. To do this, I turned on a flashlight, reached up behind, and just pushed the putty in till I could no longer see any light.

I’ve got TSx330’s running as my sides (Best Buy open box), an old Polk subwoofer I also found on Craigslist. And, along the way, I somehow picked up a pair of LSi9’s, which are magnificent in my office. So, in less than a month, I’ve gone from being a headphone guy to being a full-fledged polkanut, with seven of their speakers to my name.

Thanks all for your input along the way. Your advice was sound.

F1nut

Well, I'm glad you got the speakers working again, but I'm afraid you're going to find out that pairing inherently bright speakers with inherently bright gear isn't the best idea.

ab_ba

F1nut, again your comment has only left me wanting more! Everybody recommends Emotiva gear for the RTi12's. I can easily imagine there is something better - what do you think it would be? I wonder if there's better in this price range though? And, if it's "not the best idea", does that mean it's a bad idea? I still have time to cancel the order.... Advice appreciated, as always!

jeremymarcinko

If buying new I would purchase Outlaw over Emotiva. They are similar in price, but the Outlaws are are rebadged ATI amps, which should be a much better match with the Rti.

tonyb

ab_ba wrote: »

Everybody recommends Emotiva gear for the RTi12's. !

Not here....for the reasons F1NUT already explained. Parasound, B&k are the top choices for that line. You can find used amps of those 2 brands for under 500 bucks too.

zane77

For a home theater setup only they work, but for music too, they are a little bright with the a RTi's.

ab_ba

Guided by the comments you made, I did some amp research. First of all, I was surprised how tricky it can be to get some very simple information - MSRP, actual power per channel, etc. To make things manageable, I settled on some parameters. Keep in mind, this is a starter system - my first speaker/HT setup that isn’t simply a receiver. I’ve been a dedicated headphone user for years, and now it’s time for me to see what speakers can provide. So, these parameters definitely leave “room to grow”.

Parameters: (1) It has to be 5 channels. I know I’ll do better if I get a dedicated two-channel amp, then figure out later on how to drive the other three channels, but I don’t want to get into that right now. (2) I want at least a nominal 200 W per channel. (3) Only power matters. That is, I’m ignoring other specs like THD and amperage. I have to assume the engineers know what they are doing, and in the end, ears trump specs anyway. (4) “mixing and matching” is just fine. That is, I don’t want to consider how an amp would pair with any particular pre/pro.

So, the amps I’ve found so far that fit this bill are:
The first two are ones I would probably purchase ahead of the Emotiva XPA-5, if I could find them used (I don’t see any up for sale right now.)
- Parasound 5250 v2. $2850 new in 2011. ~$1200 used.
- Outlaw 7500. $1600 new, ~$1200 used.

- B&K Reference 200.5. ~$800 used.
- NAD M25. ~$2000 used.
- Sunfire TGA-7201. ~$2500 used.

Other brands, and why they aren’t on the list:
- Carver. Only 2 channels. Fascinating story and individual. Dizzying array of options. M1.5t is perhaps closest to what I want.
- Aragon. Only 2 channels.

The verdict: I’m sticking with my XPA-5 and UMC-200 order. At best, I will love it, and not look back for at least several years. At worst, the sound will leave me aware that there must be better out there, and the search will continue. The resale value on Emotiva gear is tremendous (I’m buying new b/c saving ~$100 on used just isn’t worth it) so when the upgradeitis strikes again, I won’t have regrets. The gear arrives in a week - I’ll post impressions here.

If anybody has another brand and model that fits my bill, would you please post it here? If you know price new and used, please include it. Maybe this thread can be a resource for others looking to drive RTi12s or comparable in the future.

Thanks all who posted.

F1nut

Only power matters. That is, I’m ignoring other specs like THD and amperage.

Ignoring amperage is a huge mistake.

ab_ba

Ignoring amperage is a huge mistake.

But, attage is volts times amps. Given the music determines the voltage, amperage completely determined by the wattage, right? Two amps that are 200 Wpc will have the same current, provided they really are 200 watts. Or am I missing something basic? The only other thing that could matter is the output impedance of the amp. Since these beasts are all designed to drive 8 ohm speakers, I'm not sure that's a parameter by which different amps will differ meaningfully.

F1nut

The topology of amps differ. Compare a 375wpc Carver amp to a 200wpc, say Parasound Halo and see which one runs out of gas first. Hint, it's not the high current amp.

ab_ba

nbrowser, may I ask which amp you like for your RTiA7's? Thanks.

ab_ba

F1nut, can you tell me how I can tell when an amp has run out of current? Does it miss some transients, or something like that? Thanks.

All this advice is valuable. I know I'll like the sound of my Emotiva. Without the ability to compare side by side, I've got to rely on your collective experience.

F1nut

The sound stage collapses, the sound gets a hard edge, the dynamics compress and the highs become shrill.

One sign of a good amp is when it's pushed it still sounds relaxed. That is, you don't notice how loud it really is until, for example, someone says something to you and you can't hear them.

ab_ba

F1nut wrote: »

The sound stage collapses, the sound gets a hard edge, the dynamics compress and the highs become shrill.

One sign of a good amp is when it's pushed it still sounds relaxed. That is, you don't notice how loud it really is until, for example, someone says something to you and you can't hear them.

Thanks F1nut. It makes me think of a good car - you glance at the speedometer and say, "am I really going that fast?"

ab_ba

OK my Emotiva gear came in last Friday - XPA-5, and UMC-200. My speakers sound really good now. Clear and full. I can definitely appreciate the difference a big amp makes - everything sounds more effortless and smooth, even at moderate volumes. I can also tell that there's "room to grow" in my setup, in particular in the bass. The RTiA12's are not thumping speakers. When I do want some thump, I switch to "all stereo" mode, and the sub kicks in. I know I'll want to do some upgrading down the line - amp, then maybe speakers. I've got my eyes open for used gear (Outlaw, Carver, Parasound) at a good price, but in the meantime, I've got a perfectly enjoyable system. Thanks again all who weighed in on this thread - the take-home messages are: Speaker rehab is not such a daunting task, at least not when they're Polks. Driving good speakers with an underpowered amp will cook your crossovers (that's what it seems the previous owner did.) And, Emotiva is a great entry to good amplification.

ab_ba

nbrowser, how'd the tube amp work out? I've got a headphone tube amp (Schiit Lyr) that I really like.

VR3

F1nut wrote: »

I'm reluctant to shell out $1600 for an Emotiva pre/pro and power amp.

If your AVR has pre outs all you need is a power amp and less than $1600 will get you better sound than that stuff.

(I asked the Yamaha guy how much it would cost me to get a unit of theirs with a true 200 W per channel. It'd be around 2000 bucks.)

I'm 99.9% sure that Yamaha doesn't have an AVR with that amount of power. In fact, I'm not aware of any AVR that is capable of 200wpc.

But, it stinks if I can't use my speakers at all without a major expenditure.

Bottom line, to perform properly those speakers require more power than an AVR can provide.

Regarding the wiring, I don't see any way I could have messed that up. The clips are different sizes, so they only fit one way onto the woofer's terminals. The woofers are all the same, so there's no possibility for a mess-up there.

I can't find the schematic for those speakers, but it's entirely possible that each woofer has a specific pair of wires coming off the crossover, not that you had the polarity wrong.

VR3

The rti12 woofers are wired together as are the midrange drivers.

5Digits

This is an old thread but a good one.

I suffer the same dilemma with the RTi12 crossovers but have plenty of upstream power to push them once the issue is fixed.

Coming from the old school of DIY electronic repair, I have already acquired the failed 3.3ohm/5watt (RTi12) and 5ohm/5watt (CSi5) resistors to correct my issue - does anyone have a listing for the caps that are present on the crossover board?

There are no burnt traces nor physical witness marks (fractured ceramic or heat distress), just failed circuit components determined by meter measurement.

Thanks

[Deleted User]

If available the best place for crossover schematic would be Polk CS at either 1-800-377-7655 or via email to polkcs@polkaudio.com. There might be restrictions since this is a current speaker. But check with them on Monday.
Usually there's enough information printed on capacitors to be able to replace.

ab_ba

Nice to see this thread has some value for people. Seeing new posts here reminds me that I've been meaning to updated my experiences, so it's out there "for the record".

I have to say F1nut is right about a lot of the comments he made here. I wanted more information from him, but I'm coming to see that his statements were certainly valid. The RTi12's are indeed bright. Pairing them with bright gear only adds to that effect. That is, they are very amp-dependent. For a speaker their size, it's surprising that the clear treble is what dominates, and the bass is present but not dominant. My Polk bookshelf speakers (LSi9, recently replaced) had more bass, though I'd say less distinct bass.

I have been using the RTi12's daily for a couple of years now - HT and music. I run them with my Emotiva XPA-5, since I need 5 channels for HT. Sound is clear, I can make out words whether in music or dialogue. Their main drawback for me is that they do not image all that well. I've tried adjusting the "sweet spot", played with toe-in, position relative to walls, they just don't create a soundstage like the TOTL systems I've been able to audition at stores and at friends' houses. If/when I upgrade, it will be for that reason. Also, they would benefit from a really good subwoofer though, and my $200 subwoofer is just distracting, so I usually leave it turned off.

I picked up a used Parasound A23 for my office / bookshelf speakers, and for fun I swapped out the Emotiva for a comparison. I preferred the sound of the Parasound, but my wife preferred the Emotiva. We agreed the sound of the RTi12's with the Parasound was clearer and more spatial, and with the XPA-5 it was fuller, warmer. I preferred the first, she preferred the second. So, the RTi12's are amp dependent, and I'm betting a Parasound A21 (twice as powerful) would fit the bill perfectly. But then, I'd want even more expensive speakers, so I live with this compromise for now.