How to set up high powered amp in home theater system - AVS Forum
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post #1 of 20 Old 04-02-2014, 01:55 AM - Thread Starter
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Hi, I am new to the forum.  I have the Marantz AV 7005 pre-amp/processor and the Marantz MM7055 140 wpc amp connected to four Cerwin Vega XLS-215's and an Infinity center speaker and two subs for a 5.2 system.  I use my system for blu-ray movies and also for listening to music and watching TV.  I have my computer connected to the system and use it to listen to my music and use the internet.  I have heard so much about how my speakers need a high wattage amp to really sound good.  I think it sounds good now, but if it can be better I'm game.  How would I go about adding something like a Cerwin Vega CV-1800 to the system and still have it sound right in 5.1 movies and for music?  I usually play my music in Multi-Channel Stereo mode.  I just can't envision how I would connect the Amp to work through all four speakers. I guess five speakers counting the center channel.  Or could I only use the CV amp for music listening only?  Will my 5.2 system still work?  How would I control the volume.  My Harmony Smart remote controls the Marantz amp volume through a corded connection to the Marantz processor.  Can someone tell me if I can add one of these high powered amps to my system and the system still function as a multimedia system?  I just can't figure it out.  Thank you in advance if someone can enlighten me to my options.

 

Also, if it means anything...  My processor and amp are connected with xlr cables...

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post #2 of 20 Old 04-02-2014, 02:16 AM
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There is no reason to do what you want to do but if you want to do it, you would simply connect the new amp to whichever two channels you want and move the speakers from the Marantz amp to the new amp, leaving two channels on the Marantz unused. Then you would rerun the room calibration software to equalize everything.
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post #3 of 20 Old 04-02-2014, 02:19 AM - Thread Starter
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Then two of the channels would be louder, ruining the 5.1 effect, right?
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post #4 of 20 Old 04-02-2014, 02:30 AM - Thread Starter
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I guess to amplify all 5+1 channels I'd have to have 3 of the CV amps. Are these people who are running the high powered amps only listening to stereo music? I haven't seen any super high powered 5.1 or better amps.
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post #5 of 20 Old 04-02-2014, 02:33 AM - Thread Starter
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Is there any validity to the claim that my speakers need 300+ watts to sound their best?
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post #6 of 20 Old 04-02-2014, 02:37 AM
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Originally Posted by dana16 View Post

Then two of the channels would be louder, ruining the 5.1 effect, right?

No, not right. The room calibration software will equalize any differences.
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post #7 of 20 Old 04-02-2014, 02:38 AM
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Originally Posted by dana16 View Post

I guess to amplify all 5+1 channels I'd have to have 3 of the CV amps. Are these people who are running the high powered amps only listening to stereo music? I haven't seen any super high powered 5.1 or better amps.

Some people do this. Mostly they are people who have no idea how much power they actually use.
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post #8 of 20 Old 04-02-2014, 02:40 AM
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Is there any validity to the claim that my speakers need 300+ watts to sound their best?

None whatsoever. The speakers are likely to do just fine with 10 watts.
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post #9 of 20 Old 04-02-2014, 02:50 AM - Thread Starter
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Well, I thought they sounded damn good myself. But seeing so many people talking about the speakers requiring these large amounts of wattage to "really get the best out of them" had me wondering. Hell, I thought I spent enough money... I like my music loud sometimes, but I guess they're trying to hurt themselves...
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post #10 of 20 Old 04-02-2014, 03:07 AM
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Originally Posted by dana16 View Post

Well, I thought they sounded damn good myself. But seeing so many people talking about the speakers requiring these large amounts of wattage to "really get the best out of them" had me wondering. Hell, I thought I spent enough money... I like my music loud sometimes, but I guess they're trying to hurt themselves...

No, they just develop beliefs and then they hear things that aren't there because of hearing bias. The belief that unused power somehow magically affects sound is a common one but a wrong one. You have way more power than you will ever use. My advice is to leave it alone.
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post #11 of 20 Old 04-02-2014, 04:36 AM
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Originally Posted by dana16 View Post

Is there any validity to the claim that my speakers need 300+ watts to sound their best?

Unlikely. Those are 95 dB/W speakers (well above average sensitivity). Your actual power needs are based primarily on:

(1) Your preferences or goals for loudness, dB SPL. Investing in a SPL meter is no big thing and it would bring a touch of objectivity into this discussion.

(2) The listening distance from the speaker to your ears

(3) the sensitivity or efficiency of the speakers.

We only actually know one of those things (3) from vendor spec sheets, and those can be optimistic.

But the SWAG answer is not so much.

Using one of the online SPL calculators

http://myhometheater.homestead.com/splcalculator.html

I get:




That is well into ear-damage territory - about twice as loud as THX standards. If your boss made you listen to your stereo like this, you could call up OSHA and maybe take him to court. Why would you do this to yourself? I doubt that you are, but a SPL meter would give us a more reliable answer.


With The proposed amp upgrade:




Notice that the amp upgrade does not give that much more loudness. At these kind of ear-damaging SPLs I doubt that there would be much real added satisfaction.
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post #12 of 20 Old 04-02-2014, 06:52 AM - Thread Starter
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I appreciate these answers which are more in line with how I felt things should be.  There's a lot of people out there saying these speakers need a lot more power and I just couldn't understand it. 

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post #13 of 20 Old 04-02-2014, 08:20 AM
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I appreciate these answers which are more in line with how I felt things should be.  There's a lot of people out there saying these speakers need a lot more power and I just couldn't understand it. 

They buy external amplifiers because they want them. They hear better results because expectation bias causes that. They conclude that the unused power they bought has some sort of effect on what they heard because others (often magazine reviewers) believe that and they spread the myth. I think sometimes there are more myths than facts in home audio.
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post #14 of 20 Old 04-05-2014, 06:54 AM
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The issue with the larger Cerwin Vega speakers isn't just about needing higher wattage amplifiers. The problem these speakers have is the large impedance swings at certain frequencies. I have personally talked with CV about this and they told me that their advertised impedance specs don't tell the entire truth. The CV XLS215 is advertised as a 6ohm speaker. But they can dip down below 4ohms with certain frequencies. I own a pair of CLS215's and the specifications say they're an 8omh speaker. But according to CV and the bench testing they do these speakers also can dip down below 4ohms. I was told sometimes down to two or three ohms. This can present a problem for most home AVR's depending on how loud you listen. So using the SPL calculator doesn't tell the entire truth about the outcome. You may be able to play them loud with your AVR but when the ohm load dips low you can run into distortion very quickly. The larger CV's act like some B&W speakers. They have large impedance dips and can put a strain on some AVR's.
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post #15 of 20 Old 04-05-2014, 07:30 AM
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The issue with the larger Cerwin Vega speakers isn't just about needing higher wattage amplifiers. The problem these speakers have is the large impedance swings at certain frequencies. I have personally talked with CV about this and they told me that their advertised impedance specs don't tell the entire truth. The CV XLS215 is advertised as a 6ohm speaker. But they can dip down below 4ohms with certain frequencies. I own a pair of CLS215's and the specifications say they're an 8omh speaker. But according to CV and the bench testing they do these speakers also can dip down below 4ohms. I was told sometimes down to two or three ohms. This can present a problem for most home AVR's depending on how loud you listen. So using the SPL calculator doesn't tell the entire truth about the outcome. You may be able to play them loud with your AVR but when the ohm load dips low you can run into distortion very quickly. The larger CV's act like some B&W speakers. They have large impedance dips and can put a strain on some AVR's.

That would depend on the frequencies where the impedance dips occur. I run speakers rated at 4 ohm nominal with a bottom of the line AV receiver in my bedroom. No overheating. No problems. The SPL calculator certainly doesn't tell the entire truth. It is quite a bit on the conservative side because it uses the anechoic factors for calculating SPL loss over distance. I would say these caculators recommend around 4 times the power required to reach the target SPL in an actual reflective room. Neither CV nor B&W speakers are difficult for an AVR to drive at normal listening levels. It just isn't a problem, popular sentiment aside.
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post #16 of 20 Old 04-05-2014, 07:43 AM
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The issue with the larger Cerwin Vega speakers isn't just about needing higher wattage amplifiers.
The problem these speakers have is the large impedance swings at certain frequencies.

Which makes them different from speakers in general?
Quote:
I have personally talked with CV about this and they told me that their advertised impedance specs don't tell the entire truth.

They are far from being alone in that sitaution.
Quote:
The CV XLS215 is advertised as a 6ohm speaker. But they can dip down below 4ohms with certain frequencies.

Not uncommon. I own these speakers that are rated at 8 ohms:

http://www.stereophile.com/content/infinity-primus-360-loudspeaker-measurements


Quote:
I own a pair of CLS215's and the specifications say they're an 8omh speaker. But according to CV and the bench testing they do these speakers also can dip down below 4ohms. I was told sometimes down to two or three ohms.

Hearsay, anybody? Show me some measurements, not rumors.
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This can present a problem for most home AVR's depending on how loud you listen.

Hearsay, anybody? Show me some measurements, not rumors.
Quote:
So using the SPL calculator doesn't tell the entire truth about the outcome. You may be able to play them loud with your AVR but when the ohm load dips low you can run into distortion very quickly. The larger CV's act like some B&W speakers. They have large impedance dips and can put a strain on some AVR's.

I've used my Primus towers and also a pair of KEF Q15 speakers that dip down to the 3 ohm region with one of the lightest-weight mainstream AVRs around - the Yamaha RX-V371. Played it loud! No problems!

My main AVR a Denon AVR 1913 is not a heavyweight either but it bests the SPL calculator I've recommended here by several dB, based on SPL meter measurements.
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post #17 of 20 Old 04-05-2014, 07:59 AM
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I'm not looking to debate if the OP needs a dedicated amp. I'm not saying he does. But his AVR needs to be able to handle low ohm loads.
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post #18 of 20 Old 04-05-2014, 09:14 AM
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I'm not looking to debate if the OP needs a dedicated amp. I'm not saying he does.

I surely didn't raise that issue. Who did?
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But his AVR needs to be able to handle low ohm loads.

Isn't that kind of a truism?

Is it a serious issue?
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post #19 of 20 Old 04-05-2014, 01:22 PM
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I'm not looking to debate if the OP needs a dedicated amp. I'm not saying he does. But his AVR needs to be able to handle low ohm loads.

Yes, and like any other amplifiers they can within limits.
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post #20 of 20 Old 04-05-2014, 04:40 PM
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Yes, and like any other amplifiers they can within limits.

+1

If real music and movies were chock full of single-frequency sounds at digital full scale RIGHT at the impedance minima, it would be a bigger problem. But when the part of the sound at the impedance minimum is 10 percent of the total power profile of any given millisecond of music of movie (probably less) the power capability becomes, at least potentially, less of an issue. Of course for amps with high output impedances frequency response anomalies (even potentially audible ones) are also possible but that has absolutely nothing to do with power . . .
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