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Re: Separate amp for fronts
davekro #251943 03/16/09 07:17 PM
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 Originally Posted By: davekro
Can you guys explain why people add a separate amp for the fronts with say a 2809, 3808 or other similar quality of amps? Is it just for more power in the stereo music listening mode? When using in HT mode, it seem the fronts are not asked to do much, compared to the center, so would have much more headroom than would normally be needed in HT mode. What am I missing here?
Because they want to, have spare money to burn and feel they are missing something with just their avr. ;\)

Many actually need the amp because they have unusually large rooms or listen at insanely loud volumes in which case they can benefit from the extra power. There are those that say they can hear better dynamics when using seperate amps. I hope to find out for myself someday.


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Re: Separate amp for fronts
jakewash #251958 03/16/09 07:57 PM
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Even in cases where the center channel carries as much or more signal than the mains, offloading the mains still frees up some power supply capacity for the center channel. It's like the difference between "one channel driven" and "all channels driven" power ratings.

This won't help in cases where there isn't enough "one channel driven" power for the center channel to keep up, but in cases where there is lots of power going into both mains and center (ie when the power supply voltage in the receiver is likely to droop under load) offloading the mains can make a difference.

The point about having bottomless power for music reproduction is also valid.

Finally, stereo amps often have nice analog power meters, which IMO always improve the perceived sound quality

Last edited by bridgman; 03/16/09 08:00 PM.

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Re: Separate amp for fronts
bridgman #251989 03/16/09 08:49 PM
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 Originally Posted By: bridgman
Even in cases where the center channel carries as much or more signal than the mains, offloading the mains still frees up some power supply capacity for the center channel. It's like the difference between "one channel driven" and "all channels driven" power ratings.

This won't help in cases where there isn't enough "one channel driven" power for the center channel to keep up, but in cases where there is lots of power going into both mains and center (ie when the power supply voltage in the receiver is likely to droop under load) off loading the mains can make a difference.

The point about having bottomless power for music reproduction is also valid.

Finally, stereo amps often have nice analog power meters, which IMO always improve the perceived sound quality



I was just going to ask about the lighter load on the PS. Glad you confirmed that thought. All the above makes sense now. Makes me lean harder towards the 3808 with a slight edge over the 2809 in power and with a larger power supply I am sure, as it weighs 11 lbs (39%) more. Then I f I feel the need to unweight the fronts from the 3808, I'll feel the surrounds will have plenty of power (maybe I am not as power hungry as some). \:D

I have read it here (JD? JohnK?) that if you bother to add an amp, it should be double the AVR's rated power. Is this just a common sense thought of not to bother with the expense for just an incremental increase, or is there more to it? This is just to edumacate myself. I don't see the need for my situation. But hey, when the term discretionary income comes back into my vocabulary, nice to have options. I am trusting we are under 'forum/ client privilege'. None of this gets back to the wife!
\:D

Last edited by davekro; 03/16/09 08:50 PM. Reason: spellin'

Dave

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Re: Separate amp for fronts
davekro #252000 03/16/09 09:15 PM
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To audibly hear a difference the power needs to double, so if you get the 3808, you will need an amp that is capable of 260W/ch to get a noticably louder system, not that you might not hear it cleaner at high SPL for the same amount of power, say an amp with 150W, since it appears outboard amps tend to have a little more headroom built in(lower specs than actual output).


Jason
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Re: Separate amp for fronts
jakewash #252007 03/16/09 09:40 PM
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 Originally Posted By: jakewash
To audibly hear a difference the power needs to double, so if you get the 3808, you will need an amp that is capable of 260W/ch to get a noticably louder system, not that you might not hear it cleaner at high SPL for the same amount of power, say an amp with 150W, since it appears outboard amps tend to have a little more headroom built in(lower specs than actual output).


Oh, that makes sense. I recall now the rule of thumb that you need to double the power to get a 3dB SPL increase. 3dB being what it takes for the average listener to notice the difference.

(Hey, JD over on the AVS thread, your repetition of this concept to me is FINALLY sinking in.) ;\)


Dave

"In theory, practice and theory are the same. In practice they're not."
Re: Separate amp for fronts
davekro #252008 03/16/09 09:43 PM
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The 260 is assuming the speaker is an 8ohm speaker. Even more if your talking 4 ohm seeing the 3803 should put out around 200 watts into 4 ohm.


Rick


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Re: Separate amp for fronts
Wid #252011 03/16/09 09:50 PM
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Rick,
Well now you are compicatin' stuff. ;\)
If I ever do think to add an amp, I CAN remember to come back here and ask for a rec. \:\)


Dave

"In theory, practice and theory are the same. In practice they're not."
Re: Separate amp for fronts
Wid #252012 03/16/09 09:52 PM
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But a separate rated at 260 into 8 Ohms is also more than likely to gain around 50% more power into 4.


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Re: Separate amp for fronts
ClubNeon #252014 03/16/09 10:04 PM
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The point being with a 4 ohm load you would need at least a 400 watt into 4 ohm amp for any real gain. A 260 watt amp is not quite going to get ya there even if you get the 50% increase....... real close though .


Rick


"A fear of weapons is a sign of retarded sexual and emotional maturity." Sigmund Freud

Re: Separate amp for fronts
Wid #252016 03/16/09 10:22 PM
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Boy are you splitting watts there Rick, or watt. Can't ya give a guy a dime's worth of watts? ;\)


Dave

"In theory, practice and theory are the same. In practice they're not."
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