Amp for RTI 150's

Fireman99 · November 2003

What would be a good amp to power my 150's? just a straight amp probably 200w /ch and up
Dan

Tour2ma · November 2003

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3059313390&category=14973
instant bi-amp...

Emlyn · November 2003

I also recommend biamping the RTi150s. To me, the best suitable new amps at reasonable cost for the RTi150s appear to be the Rotel RMB-1075 or the Outlaw model 755. It really helped my system to feed separate power to the subwoofer sections and sealed midrange/upper sections of the RTi150s.

dholmes · November 2003

I power mine with Adcom gfa-7700 175wattsx5x2 it does what I want with no shut down of the amps,I dont think I could stand anymore power, after all its not just the watts, its about the amp being HIGH CURRENT AMP!!!

dholmes · November 2003

Do you really have 4 150s?

dorokusai · November 2003

I have a Parasound HCA1500A 205wpc@8....60 amps...would power those puppies just fine.

http://clubpolk.polkaudio.com/forum/showthread.php?s=&threadid=13834

EDIT: Misqouted my own damn amplifier, 60 amps, thanks Tour.

Tour2ma · November 2003

yup... that parasound would do it...
Current Capacity: 60 amperes peak per channel

just a little shy of the sunfire...

Emlyn · November 2003

Originally posted by dholmes
Do you really have 4 150s?

Yes, but I only use the back pair for multichannel DVD-Audio or SACD. My receiver has no problem driving them for that purpose because those are the only speakers it is powering in that configuration.

4_everyman · November 2003

I second Emlyn's recommendation for the Rotel RMB-1075. I'm using one to drive a pair of RTi150s in a bi-amp configuration.
Rgds,
--pete

Fireman99 · November 2003

Doro that amp sounds nice but remember I'm in Canada =( not sure how much it would cost me in shipping, brokerage feas etc. could add up in a hurry =(
Dan

dorokusai · November 2003

Dan - It could be a "gift" right? Doesn't that negate fees?

Fireman99 · November 2003

lol this is true

but the boarder feas have gone CRAZY lately gona think about it

Thanx for thereminder though i saw you post b4 but had forgoten about it
Dan

EnoughOfThis · November 2003

There's always the Outlaw M200(wpc) monoblocks, if you wanted to biamp and let your existing receiver power the upper posts. You can get 2 M200s for $574 (or $299 each). Seems like an inexpensive way to go. I was thinking about going this route, myself. Until then, I biamped my RTi150s using the front and zone 2 amps of my receiver. It definitely makes a difference.

Speaking of biamping off zone 2 amps -- have you tried it, Dan? It doesn't look like you are using those amps for anything, based on your sig.

Fireman99 · November 2003

Enough if you were asking me the answer is no the H/K 8000 doesnt have A/B main speakers or I'm misreading your post.
Dan

EnoughOfThis · November 2003

No, not the A/B functionality. If the HK AVR 8000 has multi-room capability (i.e., zone 2), then you can use those two amps to biamp your Rti150s. From here on out, multi-room = zone 2. Since you can select what the source is for the zone 2 independently, you can actually biamp your RTi150s using your receiver. Here are some fundamental steps for doing so:

1. Connect just the top posts of the RTi150s to your receiver.
2. IMPORTANT! Remove the jumpers between the top and bottom posts on your speakers.
3. Run a preout from the front channels to any unused input (I use the tape input).
4. Select this input as the source for your multi-room/zone 2 input. This may require you to select these amps to be used for zone 2 instead of rear surround, as they can be switched.
5. Connect the bottom posts of your RTi150s to the zone 2 outputs.
6. Enjoy twice the amount of power you were getting before.

I am leaving out one crucial step, however. And that is calibrating the zone 2 volume to match your receiver's volume. On mine, this equals a -2 dB setting (I believe) on my zone 2. It takes a little more typing to go into how to do this. But here's a big hint: it involves hooking up your speakers to the front exclusively, and then to the zone 2 exclusively, comparing the volume, and making adjustments to the zone 2 level to match. Thankfully, you'll only need to do this once. Let me know if you need more detail.

The only caveat with biamping in this fashion is that you must turn on multi-room when you switch on your AVR to get any bass. It's not a problem really, just an extra step. I have macroed my remote to do this on startup, as well as shutting off the zone 2 on shutdown.

As I said, I do this with my HK 525 and it works wonders. Hope this helps.

Fireman99 · November 2003

Thanx Enough I will look into this and write back to ou if I need a little more info. Good information though never knew i cout do that!
Dan

Bemo · November 2003

Very nice work EnoughOfThis! Below is the response I got from HK to my question about doing exactly what you have accomplished. I shouldn't have let their e-mail deter me from trying. It seemed feasible to me and you've proven that it works. Do you think a speaker switch box could be used to go between 7.1 surround and the bi-amped 5.1? You would be taking the biamped woofers out of the circuit in 7.1 mode (essentially running them as RTi38's) and substituting the rear surrounds.

Has the sound quality of the 150's improved enough to make it worth the extra effort? Do you use a subwoofer? If so, how did you configure the speakers and bass management on the 525?

Here's the note from HK web support:

"Good afternoon and thank you for your inquiry. unfortunately, the AVR525 cannot be set up to perform in the way that you would like. The surround back channels can be set up to work as part of a multi-room system, but are not able to be used in a "bi-amped" manner.

Thanks again for your e-mail, and please let us know if you have any other questions.

I hope this helps."

EnoughOfThis · November 2003

The improvement gained from biamping the 150s was very significant. But you have to understand that, prior to biamping the speakers, I was starving them of power. The 150s really are power hungry. And the HK 525 doesn't quite have the power to really flex the muscles of the 150. By biamping, the lower frequencies improved dramatically. I didn't tell my wife what I had done, and she was able to recognize the increased bass immediately -- she accused me of I buying more toys.

I run the 150s on large. All other speakers are set to small, with an 80hz crossover setting (I believe). I do not have a sub. And I don't see one in my immediate future. The 150s really do sound very solid on their own.

But even so, I know that they would benefit from more power than what my receiver can give them, even when biamped. I have finally achieved clipping once during the movie "Finding Nemo", when the girl is tapping on the fish tank.

This brings up the other wonderful benefit of biamping: the fragile tweeters were protected from the potentially dangerous affects of clipping, since only the zone 2 amps (and therefore, subwoofers) were clipping. So long as you aren't using the 6th and 7th channel or multi-room capability of your receiver, I really think it is a win-win situation to biamp.

Hopefully someone else can help you with your question about a speaker switch box, as I could only hypothesize, which I am sure you could do just as well or better than me.

Emlyn · November 2003

Enough,
How did you know it was the amp sections feeding the subwoofers that were clipping? Is there an indicator on the 525, or was it something you were hearing?

I suspect that when run biamped, the impedance for the subwoofer sections dips much lower than the 8 ohm nominal impedance rating for the RTi150s when run in the standard (not biamped) mode because my RMB-1075 heats up a little more when using it to biamp RTi150s. Have you noticed any difference in heat build-up in your receiver?

Fireman99 · November 2003

Enough I have been looking this option over and If I understand it corectly I still can't do this with the 8000 it is a 7.1 recever But only has 5 speaker outputs. To go to 7.1 I need a external amp and use the pre outs for the extra speakers.
Am I correct on this one you need a amp with the 7 speaker outs?
Dan

EnoughOfThis · November 2003

Dan,

You are correct. You need a receiver that has amps for the zone2/rear surround channels. My apologies, as that is a crucial element to making this work. I should have mentioned it in my previous post. I hope I did not waste much of your time with an option that is not viable for your receiver. However, I'll fall back to my original suggestion of the Outlaw m200 monoblocks.

They are worth considering, in my opinion.

EnoughOfThis · November 2003

Emlyn,

I heard two audible popping/snapping sounds coming from the left 150's subwoofers during that scene in Finding Nemo. The 525 does not have any indication (that I have seen) that clipping is occurring. I had just assumed that it was the zone 2 amps clipping since there really isn't much else going on in that scene, other than some really heavy and constant poundings of low frequencies. It just perfectly fit the profile of clipping. It was extended duration low frequencies that resulted in the sound. I must admit, I do not have prior experience with clipping. But I imagine if it was the amp connected to the mids/tweeters, it would sound a whole lot worse than what I heard. Please correct me if I am wrong.

I have definitely noticed an increase in heat build-up in the receiver. I had just assumed that it was due to the fact that 2 more amps are now being used then before... but that assumption is likely too simplistic and you are probably right. But, I thought I read somewhere on this forum that the 150s dip much lower than the 8 ohm rating when not biamped as well? I am not sure if that was proven or not.

Fireman99 · November 2003

Enough you didnt waste my time it is another little knowlage nugget stored away for some day.

Dan

4_everyman · November 2003

EnoughOfThis:
I'm fascinated by this thread but a little confused. I'm using a Rotel RSX-1055 receiver and a separate five-channel amp. Are you saying it's possible to use the both Left/Right pre-outs AND the Left/Right speaker outputs simultaneously?

Rgds,
--pete

Tour2ma · November 2003

Originally posted by EnoughOfThis
I heard two audible popping/snapping sounds coming from the left 150's subwoofers during that scene in Finding Nemo.

may be that you distressed the drivers, not that you were clipping...

clipping does not necessarily make a sound, at least one you can hear. that's why it's so destructive...

Amp for RTI 150's

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