How about the first logical question. Why do you need (or think you need) an external amp?
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What to look for in amp specs
So it is time to add a power amp to my system. After searching around, reading different threads and what ever else I can find, checking out different amps (emotiva, rotel, parasound, mcintosh, etc.) i am still left wondering what does it all add up to. Sure anyone can look and say amp a is 200 watts while amp b is 170 watts, great almost no real difference. So when looking at amp specs which are most important? I see one amp rated at 250 watts with 50 or 60,000 uf capacitor while the other is 180 watts with 80 or 90,000 uf capacitors, does this really tell you something about what to expect? On the same amps you might also see amp a has 800kva transformer while amp b has 1500 kva transformer?! I know having a higher s/n ratio is desirable but what is really high enough to not be noticed? How about THD, lower = better right, but when does it become inaudible? SO I guess it comes down to what specs REALLY make the difference and what specs are just NICE to see? Any input is welcome, I know there a a number of you all out there with a vast knowledge on this issue so I really hope to hear from you all. Thank you in advance for the enlightening information.
1 - 20 of 87 Posts
What is it that the amp does your rec'vr doesn't?
Quote:
Originally Posted by bigbare /forum/post/16892581
So it is time to add a power amp to my system. After searching around, reading different threads and what ever else I can find, checking out different amps (emotiva, rotel, parasound, mcintosh, etc.) i am still left wondering what does it all add up to. Sure anyone can look and say amp a is 200 watts while amp b is 170 watts, great almost no real difference. So when looking at amp specs which are most important? I see one amp rated at 250 watts with 50 or 60,000 uf capacitor while the other is 180 watts with 80 or 90,000 uf capacitors, does this really tell you something about what to expect? On the same amps you might also see amp a has 800kva transformer while amp b has 1500 kva transformer?! I know having a higher s/n ratio is desirable but what is really high enough to not be noticed? How about THD, lower = better right, but when does it become inaudible? SO I guess it comes down to what specs REALLY make the difference and what specs are just NICE to see? Any input is welcome, I know there a a number of you all out there with a vast knowledge on this issue so I really hope to hear from you all. Thank you in advance for the enlightening information.
What is it that the amp does your rec'vr doesn't?
Does it really matter to answer the question? I don't mean to be rude here but I am not really asking if I need one or not. However if you must know my reciever only puts out 80 watts, not sure if that is even all channels driven, my speakers are 86db sensitivity and my seating is around 14'.
Whatever...I am not sure many are going to rush to assist you now considering the way you just treated 2 respected members of the forum. They were simple and legit questions designed to help you.
Again like I said I am not asking advice on if I need an amp or not. The help and advice I seek was in something this forum is designed for. Finding out what the objective measurements on a device mean when reading them and what to look for. Not looking for advice on weather to buy or not to buy something. I am noticing this more and more around here that when someone asks for info on something like this it ends up with people trying to give "advice" on what the person should do with their money and system. Why is they can't just give out the information? Respected or not I am sorry but that means little if you can't just answer someones request for information, to me that is being rude to the person looking for certain info. One seeks to learn and all some want to do is try to convince some one that they don't need something, to me this is disrespectful and rude. If one ask if something is NEEDED then yes by all means give all the money saving tips you can, that is being kind and respectful.
Generally, all that matters is how many watts it outputs and how tough of a load it can handle.
OK but what determines how tough a load it can handle? Mine are 6ohms nominal not real hard from what I know. Another thing that I have stumbled upon is slew rate. Never heard of it till just last night and only just saw some that actually showed this spec. Also if all that matters is watts why all the capacitor ratings and transformer ratings, THD etc?
Back in my time(80's) a good amp would start with a good design. Class A will sound best but use a lot of power. Most amps are class AB. You'd want an amp that would double it's rated power when the load was lowered(8 ohms to 4 ohms). A good damping factor was also a good indicator of a good design(400~1000). These days there's a lot of junk out there.
A good receiver will be good enough for most. Nice speakers can do a lot for your system. Keep in mind that most listening is done with
Quote:
Originally Posted by bigbare /forum/post/16892581
So it is time to add a power amp to my system. After searching around, reading different threads and what ever else I can find, checking out different amps (emotiva, rotel, parasound, mcintosh, etc.) i am still left wondering what does it all add up to. Sure anyone can look and say amp a is 200 watts while amp b is 170 watts, great almost no real difference. So when looking at amp specs which are most important? I see one amp rated at 250 watts with 50 or 60,000 uf capacitor while the other is 180 watts with 80 or 90,000 uf capacitors, does this really tell you something about what to expect? On the same amps you might also see amp a has 800kva transformer while amp b has 1500 kva transformer?! I know having a higher s/n ratio is desirable but what is really high enough to not be noticed? How about THD, lower = better right, but when does it become inaudible? SO I guess it comes down to what specs REALLY make the difference and what specs are just NICE to see? Any input is welcome, I know there a a number of you all out there with a vast knowledge on this issue so I really hope to hear from you all. Thank you in advance for the enlightening information.
Back in my time(80's) a good amp would start with a good design. Class A will sound best but use a lot of power. Most amps are class AB. You'd want an amp that would double it's rated power when the load was lowered(8 ohms to 4 ohms). A good damping factor was also a good indicator of a good design(400~1000). These days there's a lot of junk out there.
A good receiver will be good enough for most. Nice speakers can do a lot for your system. Keep in mind that most listening is done with
Most amps will have good specs. These days, it seems 200 watt / channel is pretty affordable. That's what I would look for if I was buying an amp.
I would amp the three front channels using an Emotiva XPA-3, and let the receiver handle the rest. You will have more power than you need hopefully, which is a good thing.
Going back to specs, briefly, they really don't mean much, IMO. Other than the power output, specs like THD will be excellent. If you believe in amp sound, the specs won't tell you all you need to know. If you believe a properly made amp does not really have a sound, then specs other than power output are not real interesting, IMO.
I would amp the three front channels using an Emotiva XPA-3, and let the receiver handle the rest. You will have more power than you need hopefully, which is a good thing.
Going back to specs, briefly, they really don't mean much, IMO. Other than the power output, specs like THD will be excellent. If you believe in amp sound, the specs won't tell you all you need to know. If you believe a properly made amp does not really have a sound, then specs other than power output are not real interesting, IMO.
Quote:
Originally Posted by OppoPX14 /forum/post/16892817
Back in my time(80's) a good amp would start with a good design. Class A will sound best but use a lot of power. Most amps are class AB. You'd want an amp that would double it's rated power when the load was lowered(8 ohms to 4 ohms). A good damping factor was also a good indicator of a good design(400~1000). These days there's a lot of junk out there.
A good receiver will be good enough for most. Nice speakers can do a lot for your system. Keep in mind that most listening is done with
No I am not saying there is a sound difference, nor that the specs should be able to show one. But there should be something to pull out of the specs other than the power out put. What do things like the transformer sizing mean to an amp? What does the secondary capacitance mean for an amp? Slew rate?! Like I said this one I have only just started to see and hear but some seem to liken it to being important. Why do people even bother with the specs if they say nothing important?
Quote:
Originally Posted by MichaelJHuman /forum/post/16892848
Most amps will have good specs. These days, it seems 200 watt / channel is pretty affordable. That's what I would look for if I was buying an amp.
I would amp the three front channels using an Emotiva XPA-3, and let the receiver handle the rest. You will have more power than you need hopefully, which is a good thing.
Going back to specs, briefly, they really don't mean much, IMO. Other than the power output, specs like THD will be excellent. If you believe in amp sound, the specs won't tell you all you need to know. If you believe a properly made amp does not really have a sound, then specs other than power output are not real interesting, IMO.
No I am not saying there is a sound difference, nor that the specs should be able to show one. But there should be something to pull out of the specs other than the power out put. What do things like the transformer sizing mean to an amp? What does the secondary capacitance mean for an amp? Slew rate?! Like I said this one I have only just started to see and hear but some seem to liken it to being important. Why do people even bother with the specs if they say nothing important?
The larger the transformer, the more power.
I have to admit my ignorance on what secondary capacitance means. I googled it, and found nothing, sorry.
Slew rate is of arguable importance. That, you can google, and probably find more than you want to know about it. The speed of an audio signal is pretty low, comparatively. My understanding is that any properly designed amp should have no problems tracking the input signal.
Why bother with the specs is an excellent question. I am sure if you ask different people, you will get different answers.
I used to worry about specs. I have owned five or six AVRs, and happily got over that. Rather than specs, I would rather see a proper bench test where an amp was driven continuously, just below clipping, into all channels. It should be tested full bandwidth, and for a proper duration, like 5 minutes. It should be tested into both 8 ohm and 4 ohm loads. Other than that, I don't know what specs are going to tell me.
If you really want to get into this topic, there are many online articles on amp measurements and such. Here is one article that I liked a lot
http://www.sound.westhost.com/amp-sound.htm
Quote:
Originally Posted by bigbare /forum/post/16893032
What do things like the transformer sizing mean to an amp? What does the secondary capacitance mean for an amp? Slew rate?! Like I said this one I have only just started to see and hear but some seem to liken it to being important. Why do people even bother with the specs if they say nothing important?
The larger the transformer, the more power.
I have to admit my ignorance on what secondary capacitance means. I googled it, and found nothing, sorry.
Slew rate is of arguable importance. That, you can google, and probably find more than you want to know about it. The speed of an audio signal is pretty low, comparatively. My understanding is that any properly designed amp should have no problems tracking the input signal.
Why bother with the specs is an excellent question. I am sure if you ask different people, you will get different answers.
I used to worry about specs. I have owned five or six AVRs, and happily got over that. Rather than specs, I would rather see a proper bench test where an amp was driven continuously, just below clipping, into all channels. It should be tested full bandwidth, and for a proper duration, like 5 minutes. It should be tested into both 8 ohm and 4 ohm loads. Other than that, I don't know what specs are going to tell me.
If you really want to get into this topic, there are many online articles on amp measurements and such. Here is one article that I liked a lot
http://www.sound.westhost.com/amp-sound.htm
Damping factor is a way to measure the speed and settling time of an amp.
An amp with a high damping factor will move the speaker out than in, than back to the start point(0) faster without any sloppy overlap. With a woofer, the sound will be tighter. with a midrange the sound will sound smoother.
You will most likely get a higher damping factor with an Amp as apposed to an AVR. This is because most AVR's use two transistors per channel. A good amp will/may use 4,6,8,10 or even 20(like my Classe DR9). This setup will draw a bunch more power but have much lower distortion snd a lot of control over the drivers.
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Quote:
Originally Posted by bigbare /forum/post/16892965
It seems hard to find an amp that doubles its power from 8 to 4 ohms. What exactly is the damping factor, I have seen this on a couple of amps spec. sheets and have no idea what it is. Yes I do understand that I do not need some 500 or 1000 watt mono block amps but was leaning more towards the 200 watt mark, give or take. My speakers are NHT Classic Fours which are already a big step up from my Mirage Nanosats. These speakers will be here for quite some time to come. I am not so sure my reciever is even producing 65 watts. For movies I usually don't go so loud but for music I do enjoy turning it up.
Damping factor is a way to measure the speed and settling time of an amp.
An amp with a high damping factor will move the speaker out than in, than back to the start point(0) faster without any sloppy overlap. With a woofer, the sound will be tighter. with a midrange the sound will sound smoother.
You will most likely get a higher damping factor with an Amp as apposed to an AVR. This is because most AVR's use two transistors per channel. A good amp will/may use 4,6,8,10 or even 20(like my Classe DR9). This setup will draw a bunch more power but have much lower distortion snd a lot of control over the drivers.
Thanks for the article. I have been searching around and found some things. Unfotunately I am no internet search wizard and find it hard to find what I am looking for. This is a big reason I turned to this forum to ask as I know there is people who have great knowledge on this topic. Again thanks for the input so far!
Hmmm, interesting thanks. Only thing to ask is what one considers a high dampening factor? A previous poster claimed 400-1000, not that I don't believe or trust it just curious what anyone else says.
Quote:
Originally Posted by OppoPX14 /forum/post/16893123
Damping factor is a way to measure the speed and settling time of an amp.
An amp with a high damping factor will move the speaker out than in, than back to the start point(0) faster without any sloppy overlap. With a woofer, the sound will be tighter. with a midrange the sound will sound smoother.
You will most likely get a higher damping factor with an Amp as apposed to an AVR. This is because most AVR's use two transistors per channel. A good amp will/may use 4,6,8,10 or even 20(like my Classe DR9). This setup will draw a bunch more power but have much lower distortion snd a lot of control over the drivers.![]()
Hmmm, interesting thanks. Only thing to ask is what one considers a high dampening factor? A previous poster claimed 400-1000, not that I don't believe or trust it just curious what anyone else says.
See this article on damping factor (article summary - it's not that important)
http://www.audioholics.com/education...ystem-response
http://www.audioholics.com/education...ystem-response
That article is a joke. In real world speakers, damping factor does make a difference.
In AVR's it makes no difference because very few have good damping factors.
Quote:
Originally Posted by MichaelJHuman /forum/post/16893424
See this article on damping factor (article summary - it's not that important)
http://www.audioholics.com/education...ystem-response
That article is a joke. In real world speakers, damping factor does make a difference.
In AVR's it makes no difference because very few have good damping factors.
Thank you I will read up on that. Still curious as to what the secondary capacitance does. I am assuming it stores power for the quick peaks found in music and movies, similar to having a capacitor in a car audio system. I could be way off base though. Also wonder how the transformer size effects and amp as I have seen some with higher wattage ratings with smaller one and lower wattage rated amps with bigger one?!
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