Knowledgable audio guys...why am I hearing a substantial difference between Adcom 5500 and a Sunfire Amp Series II? - AVS Forum
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post #1 of 9 Old 09-06-2013, 09:55 AM - Thread Starter
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Is it really just about the watts? Considering my speakers impedance is 6ohm...should put the power around 275wpc on the Adcom and 480wpc on the Sunfire. Now I'm not sure if this is correct and I don't understand all of it but my ears tell me that the Adcom definitely doesn't play as loud or sound as clean as the Sunfire. I noticed even at very low volume levels the Sunfire was much cleaner and dynamic.

I have a pair of Phase Technology PC 3.1 II....specs are:



Speaker: PC 3.1 II
Type: three-way, L/C/R
Tweeter (size in inches, type): 1.5, soft dome
Midrange (size in inches, type): 1, soft dome
Woofer (size in inches, type): 6.5, RPF (2)
Nominal Impedance (ohms): 6
Sensitivity: 92dB
Recommended Amp Power (watts): 20–250
Available Finishes: Cherry, Oak, Black Ash
Dimensions (H x W x D, inches): 22 x 8.25 x 11.75
Weight (pounds): 40



Adcom GFA5500 amp specs:

Basic:
200wpc @ 8ohms
350wpc @ 4ohms


http://www.adcom-usa.com/userguides/gfa-5500-ug.pdf



Sunfire amp specs: (Standard Edition)

Basic:
325wpc @ 8ohms
650wpc @ 4ohms


http://www.sunfire.com/manuals/Sunfire%20Series%20II%20Late%20Model%20Stereo%20Power%20Amplifier%20Manual.pdf
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post #2 of 9 Old 09-06-2013, 10:50 AM
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It is the way our brains work. Louder always sounds better. If you were to match levels and test the amps blind, they would sound the same. Both amps are serious overkill for the speakers so you don't need to worry about being underpowered with either one.
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post #3 of 9 Old 09-06-2013, 01:28 PM - Thread Starter
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What amp would you recommend with these speakers?
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post #4 of 9 Old 09-06-2013, 03:12 PM
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Literally anything above 20 watts per channel will work in a normal size room. You might want 50 watts per channel just to be on the safe side. As to brand, they are all about the same to me.
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post #5 of 9 Old 09-06-2013, 04:13 PM
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Quote:
Originally Posted by FMW View Post

It is the way our brains work. Louder always sounds better. If you were to match levels and test the amps blind, they would sound the same. Both amps are serious overkill for the speakers so you don't need to worry about being underpowered with either one.

Yeah, the most likely explanation is that the Sunfire has higher gain than the Adcom, meaning it's louder for the same input, and thus sounds more dynamic.

It's also possible, but pretty unlikely, that one of them has gone bad in some way.

I agree they're both overkill for the speakers. Both are pretty hardcore big-@ss amps and way beyond what would be needed (except with tough speakers in big rooms at high volumes).

For every new thing I learn, I forget two things I used to know.
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post #6 of 9 Old 09-06-2013, 06:44 PM
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Quote:
Originally Posted by beaveav View Post

Quote:
Originally Posted by FMW View Post

It is the way our brains work. Louder always sounds better. If you were to match levels and test the amps blind, they would sound the same. Both amps are serious overkill for the speakers so you don't need to worry about being underpowered with either one.

Yeah, the most likely explanation is that the Sunfire has higher gain than the Adcom, meaning it's louder for the same input, and thus sounds more dynamic.

They both have 29 dB gain. Well the Sunfire is speced at 29.029 dB gain and the Adcom is speced at 29 dB. .

Normal parts variation would still put them within about 0.1 dB. Of course those are specs and we don't know for sure that both amps were in good working order and met spec. Nobody actually tested them before and after the comparison.
Quote:
It's also possible, but pretty unlikely, that one of them has gone bad in some way.

The most likely explanation is that this was a cable-swapped sighted evaluation. Those almost always are positive for audible differences regardless of the actual facts.
Quote:
I agree they're both overkill for the speakers. Both are pretty hardcore big-@ss amps and way beyond what would be needed (except with tough speakers in big rooms at high volumes).

+1
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post #7 of 9 Old 09-06-2013, 09:49 PM
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^You're right, and I'm wrong, as usual. biggrin.gif

I should have looked up the gain on the two amps before posting, but I was too lazy.

For every new thing I learn, I forget two things I used to know.
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post #8 of 9 Old 09-07-2013, 01:23 AM
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Originally Posted by beaveav View Post

^You're right, and I'm wrong, as usual. biggrin.gif

I should have looked up the gain on the two amps before posting, but I was too lazy.

If its any consolation, the spec sheet for the Sunfire amp gives gain as a voltage ratio, while the Parasound uses the more typical dBs. I had to calculate dBs for the Sunfire. ;-)
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post #9 of 9 Old 09-15-2013, 08:45 AM
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I'm not a receiver person -- to me a receiver is a radio -- but way back around 1978 I was shopping for a receiver for a matron of my acquaintance. The shop had a cheap 15-watter on closeout and a more deluxe 20-watter for a chunk more. The salesman was trying to move me into the more expensive one, but the smaller one obviously sounded better. More dynamic playing the jazz records that she liked, clearer, cleaner, not harsh like the other.

Who knows why. Since then a whole art of audiophile design has evolved, and as with every intangible pursuit, it attracts plenty of charlatans.

But this was true then and its true now: If you're looking at watts, you're looking at one thing and sound quality is another thing.
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