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post #1 of 15 Old 04-19-2013, 09:24 PM - Thread Starter
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Hello!
I have a system with an Onkyo tx-nr807 and was informed that it was not enough power for my b&w towers

Rather than spending 1000 on an amp could I hook up another receiver that I have as a power amp and if so how? I found the pre outs on the Onkyo but what do I hook to on the other receiver? It is an arcam avr300
Thanks!
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post #2 of 15 Old 04-19-2013, 09:44 PM
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Quote:
Originally Posted by BigEinBigD View Post

Hello!
I have a system with an Onkyo tx-nr807 and was informed that it was not enough power for my b&w towers

Rather than spending 1000 on an amp could I hook up another receiver that I have as a power amp and if so how? I found the pre outs on the Onkyo but what do I hook to on the other receiver? It is an arcam avr300
Thanks!
.

Just use the pre outs for an outboard power amplifier if you want additional power. Those two avr's are much more similar than different and the Onkyo actually might have the edge on power.

If you're just looking for two channels of power (rather than three for l/c/r) the pro amps from QSC, Crown, etc can be very cost effective. Which towers of english might do you have? What are their specs?

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post #3 of 15 Old 04-19-2013, 09:56 PM - Thread Starter
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Bowers and Wilkins 703

A hifi store salesman recommended a parasound 2125 but I don't want to pay 775 just for some more power when I could sell both receivers and get a new more powerful one
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post #4 of 15 Old 04-19-2013, 10:02 PM
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Quote:
Originally Posted by BigEinBigD View Post

Bowers and Wilkins 703

A hifi store salesman recommended a parasound 2125 but I don't want to pay 775 just for some more power when I could sell both receivers and get a new more powerful one
First learn about amp ratings. Also how much distortion can still come into play. Also about how much additional power actually translates into spl differences.

The parasound is rated 125w/ch, your Onkyo is fine in comparison. Just what are the specs for your speakers? I didn't find any quickly (and since they're not mine that's all I'm going to do).

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post #5 of 15 Old 04-19-2013, 10:12 PM - Thread Starter
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Product Description

3-way vented-box system, 2 x 6.5" paper/Kevlar cone bass drivers, 6" woven Kevlar cone FST midrange driver, 1" alloy dome tweeter, 38Hz-25kHz ±3dB, 8 Ohm impedance, 90dB sensitivity, 120lb/pair.
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post #6 of 15 Old 04-19-2013, 10:16 PM
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Quote:
Originally Posted by BigEinBigD View Post

Product Description

3-way vented-box system, 2 x 6.5" paper/Kevlar cone bass drivers, 6" woven Kevlar cone FST midrange driver, 1" alloy dome tweeter, 38Hz-25kHz ±3dB, 8 Ohm impedance, 90dB sensitivity, 120lb/pair.

Okay, try plugging numbers into this calculator to see what w/ch differences make http://myhometheater.homestead.com/splcalculator.html

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post #7 of 15 Old 04-20-2013, 01:56 AM
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Don't listen. That NX-807 is a 7.2 channel reciever with 135 watts driving 2 channels. It can power your speakers and then some.

Depending on its max power rating, it might use significantly less than that when powering 5 or more speakers, but I seriously doubt if it is driving less than 80 or 90 watts per channel when using 5.1 configuration and with those speakers, you should be just fine.

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post #8 of 15 Old 04-20-2013, 07:54 AM
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The model number of your speakers is missing!

What model are they? You need to look at the graph of impedance VS frequency for your speaker model.

The ARCAM receiver is rated to put out 100 watts per channel with ALL 7 CHANNELS DRIVEN. The ONKYO can't even come close to that.

You should be using the ARCAM, NOT the ONKYO. It probably has FOUR TIMES the total power available compared to the ONKYO to drive your speakers, and its sound quality is superior.

It also has a far superior power supply that can handle the peak current demands of your speakers much much better.

That ONKYO probably will not put out more than 50 or 60 watts per channel with all channels driven, if that. Its power specs are very deceptive and incomplete, so ignore them.

Everything about the ARCAM is superior to the ONKYO. Use it and sell the ONKYO and you will be just fine.

Comparing the ONKYO to the ARCAM is like comparing a Chevrolet Malibu to a BMW 735; they are in a totally different class in power and engineering.

Yes, I know it is an older unit and does not have HDMI, but its superior engineering and excellent amplifiers are well worth the price of some component-video cables, which will give you the same video quality.

Would you rather have last year's BMW or this year's Chevrolet?
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post #9 of 15 Old 04-20-2013, 07:02 PM
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Quote:
Originally Posted by commsysman View Post

The model number of your speakers is missing!

What model are they? You need to look at the graph of impedance VS frequency for your speaker model.

The ARCAM receiver is rated to put out 100 watts per channel with ALL 7 CHANNELS DRIVEN. The ONKYO can't even come close to that.

You should be using the ARCAM, NOT the ONKYO. It probably has FOUR TIMES the total power available compared to the ONKYO to drive your speakers, and its sound quality is superior.

It also has a far superior power supply that can handle the peak current demands of your speakers much much better.

That ONKYO probably will not put out more than 50 or 60 watts per channel with all channels driven, if that. Its power specs are very deceptive and incomplete, so ignore them.

Everything about the ARCAM is superior to the ONKYO. Use it and sell the ONKYO and you will be just fine.

Comparing the ONKYO to the ARCAM is like comparing a Chevrolet Malibu to a BMW 735; they are in a totally different class in power and engineering.

Yes, I know it is an older unit and does not have HDMI, but its superior engineering and excellent amplifiers are well worth the price of some component-video cables, which will give you the same video quality.

Would you rather have last year's BMW or this year's Chevrolet?

Actually, you can usually look in the back of a reciever's manual and see the total power consumption of the reciever. Then divide that up by the number of speakers you are driving and that should get fairly close to what you are pushing. If you are driving all channels simultaneously that might be a problem, but for most surround content in movies, it shouldn't be an issue. But I don't have to tell you (of all people) that.

Stand tall and shake the heavens...
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post #10 of 15 Old 04-21-2013, 07:42 PM - Thread Starter
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Thanks so much for all the replies!
I can use my money on something other than a power amp, that is clear

Do any of you have an Apple Time Capsule? I would like to find a way to stream music from this to my receiver
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post #11 of 15 Old 04-21-2013, 07:56 PM - Thread Starter
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Also, regarding component cables, is there a brand you cam recommend
I have seen every dollar amount from free to hundreds of dollars for one cable
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post #12 of 15 Old 04-21-2013, 09:14 PM
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I don't know how long you need them, but these from Monoprice are very well made and are low priced. They have them from 1.5ft long to 100ft.
http://www.monoprice.com/products/product.asp?c_id=102&cp_id=10235&cs_id=1023502&p_id=6311&seq=1&format=2

Those or either of the top 2 products here at Blue Jeans Cable:
http://www.bluejeanscable.com/store/component/index.htm
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post #13 of 15 Old 04-22-2013, 04:49 AM
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Quote:
Originally Posted by BigEinBigD View Post

Hello!
I have a system with an Onkyo tx-nr807 and was informed that it was not enough power for my b&w towers

What was the source of the information?

What was the confirming evidence?
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post #14 of 15 Old 04-22-2013, 05:08 AM
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Quote:
Originally Posted by BigEinBigD View Post

Bowers and Wilkins 703

A hifi store salesman recommended a parasound 2125 but I don't want to pay 775 just for some more power when I could sell both receivers and get a new more powerful one

Here's the relevant info on the 2125:

http://www.parasound.com/nc/2125.php

125 watts rms per channel into 8Ω, all channels (2) driven
200 watts rms per channel into 4Ω, all channels (2) driven
200 watts rms per channel into 2Ω, all channels (2) driven

Here is the corresponding info for your existing Onkyo tx-nr807

135 watts minimum continuous power per channel, 8 ohm loads, 2 channels driven from 20 Hz to 20 kHz, with a maximum total harmonic distortion of 0.08% (FTC)
145 watts minimum continuous power per channel, 8 ohm loads, 2 channels driven at 1 kHz, with a maximum total harmonic distortion of 0.7% (FTC)
160 watts minimum continuous power per channel, 6 ohm loads, 2 channels driven at 1 kHz, with a maximum total harmonic distortion of 0.1% (FTC)


B&W 703 Info

http://www.hometheater.com/content/bw-703-htm7-705-asw750-surround-speaker-system-measurements

"The B&W 703's ported enclosure is tuned to approximately 32Hz, and its minimum impedance is 2.8ohms at 100Hz. The impedance remains below 4ohms from about 79Hz to 400Hz—a region of the frequency spectrum that is dense with fundamentals and requires more of an amplifier, over time, than even the deep bass (which makes huge but less constant demands). I would judge this speaker to be moderately difficult to drive. For that reason, I would conservatively rate its nominal impedance at 4ohms. The 703's sensitivity measured about 88dB/2.83V/m."

IMO the relevant comparison would be between the NR807 AVR versus the 2125 with 4 ohm load.

On the test bench a slight edge would go to the Parasound for its 200 wpc spec into a resistive 4 ohm load. While we have no rating for the NR807 at 4 ohms, its 6 ohm performance (160 watts) is probably indicative.

The obvious problem is that 200 watts is only about 1 dB more power than 160 watts. The Parasound's most likely benefit are mental rather than physical. This is a barely audible difference. For reference purposes it takes 10 dB more power (coincidentally 10 dB more power) to create the impression of "twice as loud".

At this point the most satisfying upgrade would probably be a subwoofer. The two 6.5 woofers in the 703 appear to lack punch below 50 Hz. They certainly lack dynamic range. By adding a subwoofer a considerable power load will be taken of off the main channels of the AVR by using a crossover point of 80 Hz or so. I would recommend budgeting the same amount of money or more as you had considered for the power amp upgrade. Subwoofers from Hsu and Rhythmic have a good reputation for price/performance and good general performance.
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post #15 of 15 Old 04-23-2013, 06:44 AM - Thread Starter
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I appreciate ya!
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