RTI-12 Setup Questions

Enzo2400

Hi guys,

I've purchased a pair of used RTI-12's that are in excellent condition. The intended use was for 2-channel stereo. Right now they are hooked up to a Yamaha 797 2-channel amplifier. There is no subwoofer connected. The amp is rated at 100 watts/ch @ 8 ohms. This pairing is excellent at low level volumes, but when the volume is set at about 60%, I get distortion in the highs.

I'm thinking about moving these speakers over to a home theatre setup, but I'd like to hear these units kick to their full potential in 2-channel first. It would be good info to know which amps are recommended for stereo and home theatre.

After reading some posts on this forum I've realized that I will need a power amp for these speakers. But I have a few questions about everything that's required so I can avoid the trail and error process of buy and selling equipment.

1. Which 2-channel and home theatre power amps (new or used) would you suggest for the RTI-12's?
2. Will a power amp solve the distortion problems of the highs or will I definitely need to hook up a subwoofer?

Good to be part of the polk club.
Thanks guys in advance.
Enzo.

Dawgfish

Enzo2400,

Welcome to Club Polk. I have a pair of RTI-12s that I am using as mains in a 7.3 home theater setup. I also use these for two channel music mode. My answers for your quetions are:

1. There are a variety of good amps out there new and used that will do a great job powering the 12's, but I would get one that is putting out at least 200 watts of good clean power per channel. I have tried Emotiva, Monster, Adcom, and Carver with the RTi-12s, all with good results. An Emotiva XPA-2 comes to mind as an amp that will match up very well with the RTi 12s for both music and home theater, but that is just one suggesting. If you can get out and listen to a variety of different amps to see what sounds best to you, I highly advise doing so. People have different tastes.

I am currently biamping my RTi-12s with about 450 wpc and the increased wattage has really gotten these things to sing. They sounded good at 250 wpc, but there is no comparison between then and now, especially listening to two channel music. I turn my subs completely off now while listening to music and you would swear they were still on. Imaging is also better, and the soundstage widened considerably. I guess the moral of this story is get as many good clean watts to your RTi-12s as you can afford or find available. 200 wpc channel is good, but you wont be getting the most out of these speakers until you start getting around the 400 wpc range based on my experience with them.

2. The amp will definitely make a huge improvement in distortion levels with the RTi-12s provided you are using good sources and your are not turning the volume up to insane levels. The RTI-12s are workhorse speakers and can take an astounding amount of good, clean power. I can turn mine up to crazy levels without any noticable distortion. A good amp will make a huge difference over a reciever.

Needing a subwoofer is a different animal all together than the issue of distorting highs, unless the reason you are getting distorted highs is you feel the need to turn the volume up to get increased bass response, and this high volume with the insufficient clean power the Yamaha reciever is putting out is causing the distortion. Adding a sub will definitely fill in the bottom end. When i was pushing my RTi-12s with 250 wpc, there were still some instances where I used my sub even while listening to music. After I added the extra wattage to the 12s, I now turn my subs off while listening to music 98% of the time. I am astounded at how much bass and how low these things are actually capable of. It is also nice tight, clean, and musical bass. I really like it. With my current set-up, I don't feel the need for a sub with music. Of course with home theater this is a different story. I turn my subs back on for home theater for added low end punch and effect. If you listen to a lot of rap and hip-hop (which I don't), you may want to consider a sub also. Hope this helps.

Steve

bruss

a used adcom gfa-555 is a good place to start. pretty easy to find and fairly inexpensive as far as amps go. there are alllll sorts of posts related to this topic here.. you should be able to find all the info you need fairly easy

Enzo2400

Cool, thanks for all the info Dawgfish.

I was just looking into some of the amps you suggested, came across used Adcom GFA-555 with preamp, Carver PM 2.0T and Carver TFM-45. Selling prices are $550, $325 and $240 respectively. The Carver's seem to have about double the watts per channel as the Adcom, but I read somewhere that the reliability of Carver's are questionable, especially the later models being made in China.

If you could give your opinions on the above units I would appreciate it.

Pretty sure these topics have been discussed to death. Once I get more familiar with the site I'll do more of the research myself. Thanks for helping out a Polkie.

Enzo2400

Another concern,

My Yamaha 797 puts out 100 watts per channel.
The Adcom GFE-555 puts out 200 watts per channel.

Okay so I guess they both put out like my high school prom date... haha.

No really, my point is how much more of a difference will 100 watts make?
Or is it not just the wattage, but more the difference between Yamaha and Adcom.

Your input is appreciated, thanks.

Dawgfish

Enzo2400,

Good questions. Adcoms are known for their reliability and longevity. I have a GFA 555 that has to be 20 years old and it is still going strong. The older GFA's do have known issues of leaking caps, but it seems to be an easy and relatively cheap fix. Ben here on the board is an expert on this and could easily replace the caps for you if ever needed.

Some of the Carvers are known to have reliability issues, but this may or may not be overblown a bit. I'm not quite sure. I think generally speaking Adcoms are thought of as being more reliable than Carvers. I have a TFM 35 that I really like and have had no problems with it.

To me the decision between these two amps really comes down to how good a deal you can get and sound preference. My Adcom has slightly more detail, crisper highs, and better bass punch than the TFM-35. The TFM-35 has a warm, laid-back sound to it that is very easy to listen to for hours on end. I like the sound of both of them, but I prefer the GFA-555 a little more for the better bass punch it gives my RTi-12s. It's probably the better all around home theater and music amp. The Carver is probably the better of the two amps for sustained two chanel music listening however. Agian, I highly recommend listening to both if you can and get the one that better suits your needs and tastes.

As far as the second question goes. There is no comparison between the wattage of a reciever and that of a good dedicated power amp. The power ratings for most recievers are overrated in most cases. In most cases 100 wpc from a dedicated power amp would be far superior to 100 wpc coming from a reciever. The amp would have much more reserve power, head-room, and dynamics than a typical reciever. Ben likes to say a watt is not always a watt and he's right. You have to be careful playing the wattage game because not all watts are created equal. In general though, 100 wpc from a good dedicated pwoer amp will be in a whole other league than 100 wpc from a reciever. The difference in power between the Adcom(and any other good power amp) and the Yamaha (and just about any typical reciever) will be like going from night to day. Hope this helps.

Enzo2400

Thanks dude, this information is gold.

I'm going to look into this Adcom GFE-555 amp with GFP-555 preamp for sale. I've got a great local electronics guy that can look after the leaking caps issue if there is any. I made an offer for $400 but he didn't go for it. I'll throw him $500 and hopefully he'll bite.

Does the $550 original selling price seem like a fair deal? He says it is an MKII model, described to be in excellent working and cosmetic condition.

If I decide to hook up a subwoofer on this unit, which Polk sub would you suggest using with the RTI-12's? How exactly does the sub hook up and does it relieve some of the pressure from the front speakers?

Thanks again.
Enzo.

Dawgfish

The $550 he is asking for the GFA-555 and GFP 555 is probably on the upper end of the asking price for these two items together. In the Craigs List markets that I generally watch in the southeast, most GFA-555s (inlcluding the MkIIs) are about $250-400, with most going in the $300-350 range. Most of the 500 series preamps you see go for about $100-150. I would offer him $450 to $500 for both and provided they are in good shape like he says, you will be getting them at about the right going price.


Any of the Polk DSW or DSW micropro subs would match great with the RTi12s. I own the DSW Pro 400, 500, and 600 and have been impressed with the performance of all. For strictly music, I like the 400 best. It has nice tight punchy bass. The 600 goes the lowest and lowdest and is the best for home theater out of the DSW series. The 600 also does quite well with music. The 500 is probably the best all around handling home theater and music equally well, though it's not quite as tight as the 400, or reaches quite as low as the 600. I don't have personal experience with the Micropro subs, but I hear great things about them and would love to try one.

If your reciever has a dedicated LFE output, connect the sub to that using a good quality subwoofer cable. If your reciever does not then you'll have to run the front main right and left speaker cables to the right and left speaker line level connectors on the subs, and then run speaker wire from the right and left main outputs to the right and left main speakers. Most modern recievers and preamps have LFE outputs though.

Having a good sub definitely relieves some of the preasure from your front speakers, but it really depends on how you set up your sub on the reciever. Most people recommend setting your speaker setting to small on the reciever or preamp and setting the subwoofer crossover to 80HZ. Setup this way, any signal below 80hz will be sent to the subwoofer instead of the speakers. and since the speakers are not having to produce these very low frequencies, a lot of the power that would be tied up to produce the low frequencies (which take more power to produce btw) is now free to drive the mid and highs. This is the standard setup for home theater.

I have a little different setup than most people however. I am running RTi12s as fronts, RTi10s as surrounds, and RTi8s as rear surrounds. I didn't buy all of those towers, only not to take advantage of their increased bass response and range. Otherwise I would have just bought bookshelves or sorrounds. I am one of those wierd people who actually likes to listen to 7 channel stereo sometimes. In this mode (and 2 chanel stereo also) I set my speakers to large and set my crossover to 40 hz. Since I am powering all of my speakers with external amps, all of the towers sound nice running at almost full range with good bass response. Lately I have even been running this setup with movies also. I don't get quite as much bass slam, but it is smoother and less offensive to the neighbors, while still having a lot of impact. RTI-12s are a helluva powerful speaker with the right amplification. It's ashamed to cross them over at 80 hz and not take advantage of their full potential sometimes. Running them this way (near full range) they produce outstanding bass response. I sometimes have to check to make sure the subs are indeed turned off!

cnh

Great post Dawg!

Enzo...Dawg knows what he's talking about. I run an old adcom myself; the original 555 and it sounds great with even a pair of M70s. The RTI-12s are the best of that series. If I were upgrading that's where I'd go! I can also 'believe' they'd sound even better with more than 200 watts! Nice to know Dawg!

I have nothing to add here. Just loved reading the exchange. This is CP at its best.

cnh

Enzo2400

Excellent information man.
I'm in negotiation right now for $500 on the Adcom amp/preamp.

Some more questions I had bouncing around,

1. Is it necessary to have a seperate equalizer hooked up to this amp/preamp?
2. Will running this size of amp require upgrading my circuit breaker? What is the minimum amount of current needed to run this if I decide to set up the DSW-4000? (Probably will not go that heavy but it's good to be prepared).

To answer a previous statement you made, I listen to all genres of music. Even though I'm not listening to hip hop everyday, if I do want to hear it I would hate not having a system not set up to handle it.

Basically, I want a system that can handle anything I throw at it, at any volume level, for hours on end without any problems.

If you could let me know anything else I may need to do or get to set up with the discussed units. I am, afterall, a Polkie and not to familiar with all the little details and hook ups that come so naturally to those with years in the hobby.

How long can I milk the Polkie excuse to get easy answers? Haha...

Alright cool guys.
Enzo.

Dawgfish

CNH,

Thank you very much for the kind words. I'm glad that your enjoying your GFA-555. That is one workhorse of an amp. Adcoms are always a great choice, especially used.

Enzo,

A seperate equalizer shouldn't be necesary. Your receiver should at the very least have some sort of tone control on it for bass and treble. It very well may have a built in adjustable manual eq. I'm not familiar with that model Yamaha, but many recievers do have adjustable eqs so check the owners manaul or setup menu on your reciever. Your reciever may also have some sort of automatic setup program on it. If it does, run the program, then make manual adjstments to suit your tastes if necesary. Of course if you want to add a seperate eq. for your own tastes, that's an entirely different thing alltogether. I can remember being mesmerized in my younger days by eqs. that also had spectrum analyzers on them. I enjoyed the "light show" aspect of them. Sepereate eqs. are really not necesary for most modern recievers and preamps however.

As far as the circuit breaker in your home, provided the wiring in your house is wired according to current specs and you have 15 amp receptacles installed in your home, you shouldn't have to change any of the wiring in your home. Most amps and subs will work just fine with 15 amp receptacles. There are a few super high output, boat anchor amps out there that do require 20 amp receptacles, but the vast majority of the subs and amps you will find will run just fine off a 15 amp receptacle.

The only other pieces of advice I could give you are run the best interconnect cables and speaker wire you can afford. I run Adudioquest Diamondback interconnects with great results. Audioquest makes a budget interconnect series called the Sidewinder that I've also had great luck with. As far as interconnects go, look for ones with plenty of sheilding, are fairly flexible, and have gold connecters.

I also use ten and twelve guage Belkin speaker wire terminated with banana plugs. It sounds good to me. Eventually I am going to try some of the fancier speaker wire out there, but at the time this is what my budget would allow. I would look for the heaviest guage oxygen free copper wires you can afford. Blue Jeans Cable is a great plact to find this. Hope this helps.

P.S. A properly amped pair of RTi 12s will handle anything thrown at them, including hip-hop and rap without a wimper. Adding a subwoofer though, will further fill in the low end and allow for greater home theater capabilities. The combination of a properly amped pair of RTi12s and any of the DSW or DSW Micropro subs (or any other good sub from other manufacturs) will be a combination that can handle anything and put a big ol' grin on your face. You'll love the results.

Enzo2400

Dawg,

I've looked on the back of my Yamaha and didn't find any LFE output. Seems if I will need to set up a subwoofer, I'll need to wire it as you mentioned earlier.

Will this offer the same performance as an LFE output?

I do have a adjustment knob that acts as an EQ control on the Yamaha. It has been fine thus far as an overall adjustment, just wondered if that were considered very basic and a seperate EQ was necessary for better control of sound.

Interconnect cables, speaker wiring and banana plugs should be good. My electrical wiring is standard so there shouldn't be any issues there.

Awesome guys. Once I get this together I'll let you know how it's performing.

Enzo2400

I ran into a few problems...

I'm setting up the Adcom amp/preamp and a pair of Cerwin Vega 12 inchers that are rated at 300 watts a side. Using the basic setup, I end up blowing a fuse in one of the speakers. I was pushing them pretty hard to the point that woofer's make a *pop* sound, but backed off a little bit. It was playing for about 4 minutes before it happened.

So needless to say once the fuse on that one speaker went the left side didn't play. I'd hate to have this happen if I were entertaining folks and didn't have a supply of fuses handy.

1. Did the fuse go because I was pushing them to hard?
2. Are the speakers not powerful enough for this amp?

Then I set up the RTI-12's. I didn't push these ones as hard and was impressed with the volume level. The problem is with the Adcom amp/preamp is that there's very little adjustment so the piercing highs can't be controlled. I typically listen to music with the highs lowered and bass increased. For me it's a lot easier on the ears and gives the music a solid sound.

Right now I don't have the Yamaha hooked up at all. It has the EQ adjustment knob that would definitely help the situation.

3. Is it possible to hook up the receiver with both amp and preamp?
4. If I want to use my receiver do I have to disconnect the preamp?

I was also a bit disappointed with the bass output of the RTI-12's listening to tracks with heavy basslines. But as Dawg mentioned, with the added sub discussed earlier it will fill out properly. Distortion I didn't notice until at very hgh volumes.

When I read the Adcom manual, it mentioned you can set up two pairs of speakers to this unit. I tried setting up the RTI-12's with the one Cerwin Vega 12 that didn't blow a fuse. When I connected them to the amp, I put both black wires in one banana plug and the reds in the other. Seems to play pretty good, though I couldn't get a good feel for the sound since it was only 3 speakers.

5. How does the 2 pair of speaker set up work out?
6. Can the Adcom handle 2 pairs of heavy speakers, both 8 ohms?
7. How long can the amp sustain 2 pairs at high volumes?
8. Is there less pressure on the RTiI-12's with the added set of speakers?

Another issue that came up was the banana plugs don't fit into the amp all that well. They almost seem too long because they can easily fall out. These are the same banana plugs I used on the Yamaha and they fit correctly. Maybe there are different types? I'll have a look tomorrow when I go to buy a fuse.

The Adcom units themselves are in excellent condition. I can't say to much for the operation since I've only used them for a few hours and haven't sorted out all the other variables yet.

Hey, I know it's a lot of questions, but I'm sure you dudes have lots of experience with all this. Any input you could give a Polkie would be cool.

Thanks.
Enzo.

Enzo2400

Nevermind about the equalizer questions, Dawg. I understand what you meant now and got it working without using the Adcom preamp. Thanks.

Dawgfish

Enzo,

Sorry I'm just now responding. I left my laptop at work all weekend. I'm glad you figured things out, let us know how things are sounding and if you have any more questions.

Steve

Enzo2400

Dawg, I know you recommended the DSW's, but is there a reason you didn't suggest the PSW series?

I'm looking into either the PSW10's or 125's since they would match the RTI-12's perfectly in appearance.

How about splitting the LFE on my Yahama to set up two PSW10's? 125's?

Thanks for your help.
Enzo.