what to look for in a good amp?

[newton75]

hi comunity

i am reading about amps tech specs , a very helpfull member recomended the Pyle PTA2 Mini 2x40W amp
for @ 50$ that fits what i need.
specs are :

Harmonic Distortion: 0.3%
2 x 40 Watt RMS at four Ohm
Frequency Response: 20 Hz-20 kHz
Power Fuse: 1.5 A, 250 V Fast-Acting (.2 x .8 inches)
Tone Controls: Bass & Treble: +/-10 dB (100 Hz/10 kHz)

but i realize that i dont understand that and im curious XD , i was reading some wikipedia but i whould like to have a simple explanation about the specs so i can understand what to look for in an amp.

i was also looking in amazon and i found these 2
amps for @ 100$ my 2 speakers are 80w 6h nominal Pioneer SP-BS22-LR Andrew Jones Designed Bookshelf Loudspeakers

with the woofer Dayton Audio SUB-1000 Frequency Response 30-140 Hz the 12" is 25 Hz to 140 Hz

i found this polk amp Polk Audio PSW10 about the same price freq response 35 Hz - 200 Hz (i dont know if its better )
the lower the freq response the better right?

OSD Audio AMP120 Pro Series
AudioSource AMP-100 Stereo Power Amplifier
Sherwood RX-4105 this one seems to be too powerfull for my speakers.


if you tell me that one of those amps for @100 is going to be amazingly good compared to the 50$ one . i can save some more money and purchase it XD
i was unable to find any revews about the osd audio or the audiosource amps ...

thanks for all your answers

 

[j_garcia]

I ran my BS22LRs hard with my Emotiva XPA-3 (200WPC @ 8 Ohms) for days with no issues. Using the wattage rating on the speaker itself is practically useless, so you can more or less ignore it. Having more power than the rating is not an issue because you are not USING that power all the time, so the speaker's rating is a bit misleading.

The Polk sub is a no go. I've owned it, definitely skip it.

I'd probably skip the Audiosource amp too. They haven't really been the same since they got bought. I own an older version Amp100 and two Amp300s and they are pretty solid, but their value for performance seems to have dropped off some in recent years.

Afterlife2 here is using one of those Pyle amps and says it's decent for the price, so it is probably a safe bet to start with. Pyle isn't known for being top quality though, so YMMV. There are plenty of Topping and Lepai amps at various wattages and prices on PartsExpress too and they are also a good bang for the buck.

 

[AcuDefTechGuy]

I would rather have Sherwood than OSD (which is the same as AudioSource).

 

[newton75]

thanks for your answer . and afterlife2 was the one helping me (he (corrected) is amazing )


so the amp power doesnot matter i can use a 500w amp with my BS22LRs and they will not burn or something XD

thanks for the advice . on the sub

so basicaly there is nothing special that i need to take into consideration when choosing a amp ? just choose something with good price good reputation/quality
and options?

is sherwood a good brand ?

 

[Goliath]

so basicaly there is nothing special that i need to take into consideration when choosing a amp ? just choose something with good price good reputation/quality
and options?

Most modern receivers have oodles of clean power to drive any reasonable speaker system to ear-bleeding levels in a typical room. What is important is how the system will be used in the space which will dictate what features you need. More expensive models include better quality room correction and features that allow you to distribute sound or picture in one or more rooms in the house. All depends how the system will be used.

 

[j_garcia]

Afterlife is a dude

I don't mean that it doesn't matter at all on the power rating, because the rating means if you feed it more than that actual rating something in it WILL fry. But generally when you have enough power you won't need to crank it up to 200W of actual use. Meaning you are typically using only a fraction of the rated power of an amp.

Speakers more commonly fry with not enough power because the demand is higher than the amp can deliver and the signal becomes clipped (distortion) and damages the speaker. I am currently driving my BS22s with a small ~30W amp and they do just fine. So long as you realize the point at which you can't turn it up anymore, as that is when you will potentially start to damage things.

 

[AcuDefTechGuy]

$230 Sony 520 power output for 2Ch into 8 ohms/ 2Ch into 4 ohms/ 5Ch into 8 ohms @ 1% THD: 141.7WPC/ 160.6WPC / 81.3WPC.

So yeah, if a $230 AVR can output 161 WPC into 4 ohms x 2Ch for music, that is more than enough. You would need 320 WPC to increase the volume by 3dB.

 

[newton75]

ok . i get it .thx. and my room is not a big room .
how do i know if my amp has the new tech (oodles of clean power to drive any reasonable speaker system to ear-bleeding levels in a typical room) ?
is there any way to measure tha power of an amp ? i've heard that some amps deliver lowe power than what the manufacturer says

thanks for your answer acudeftechguy , i was unable to understand 80% of the post is in audionese XD (i'm learning though)

what is the best amp @ 100$ ?

 

[Goliath]

Speakers more commonly fry with not enough power because the demand is higher than the amp can deliver and the signal becomes clipped (distortion) and damages the speaker.

Technically it's not the distortion from clipping that does the speaker in. It's the additional power derived from the clipping that may possibly exceed the thermal power handling of the speaker. Too much power is what does the damage, whether it was clean or distorted makes little difference.

So long as you realize the point at which you can't turn it up anymore, as that is when you will potentially start to damage things.

If you have a pair of speakers with a power handling of 120W and you are using a 30W amp then clipping cannot result in damage - you can clip that amplifier until you are blue in the face and you'll never cause thermal issues because the amplifier will be incapable of delivering enough power to cause damage. What will happen is the speaker will sound absolutely horrendous at high output levels due to the extreme distortion.

 

[AcuDefTechGuy]

what is the best amp @ 100$ ?

I think the first question is, why do you even need an amp?

Why not just use an AVR?

But for amps, I think the best $100 amp is a used amp. For example, a new Crown XLS1000 is about $280, but a used one may be $100.

 

[Goliath]

is there any way to measure tha power of an amp ? i've heard that some amps deliver lowe power than what the manufacturer says

If you are look at the test bench results over at HomeTheaterMag you'll find that most modern receivers can deliver in excess of 60W into 5 channels and 100W (or more) into 2 channels. This is on a test bench using sine waves. In other words, the most grueling test that amplifiers ever face in their lifetimes.

In practice amplifiers are not taxed 100% of the time, so in reality have more headroom available when driving musical signals.

A speaker of moderate sensitivity (87 dB) in a typical room at a typical seated distance (8-10 feet) would need less than 100W to deliver well over 100 dB SPL (note = pretty loud). Speakers of higher sensitivity typically require even less power to achieve the same SPL.

Most of the time the average power will probably be less than 1W - music has a crest factor of 20 dB or 100 times the average power. If you're using 1W on average, you may need 100W on the most extreme program material. But most typical people I know don't listen to music/movies at 100dB+ so the actual power requirements will be far less in reality.

The other thing is that many people today use subwoofers and bass management in their systems which further reduces power requirements from their systems. I'd wager most people never reach close to rated output on their amplifiers, even under stressful conditions. Unless, of course, you are in a room the size of a gymnasium or require concert level SPL, or have incredibly insensitive speakers.

 

[newton75]

thanks a loot for the answers
is for a pc and my xbox. 360 i dont know much but maybe the avr is more expensive than a regular amp ? , maybe i can get more power from an amp for the price than a AVR?
what do you recomend? , a good AVR for 100$ ? point me to one .
brand new plz if used ill look for it in ebay XD

 

[j_garcia]

Technically it's not the distortion from clipping that does the speaker in. It's the additional power derived from the clipping that may possibly exceed the thermal power handling of the speaker. Too much power is what does the damage, whether it was clean or distorted makes little difference.

Agreed; just didn't want to get to that level of detail here because it was more than likely needed to get the point across since that is not what the question is...that's a question that hadn't been asked yet.

If you have a pair of speakers with a power handling of 120W and you are using a 30W amp then clipping cannot result in damage - you can clip that amplifier until you are blue in the face and you'll never cause thermal issues because the amplifier will be incapable of delivering enough power to cause damage. What will happen is the speaker will sound absolutely horrendous at high output levels due to the extreme distortion.

I think there are a lot of factors that will come into play there as your example is not quite correct. I've driven a tiny speaker rated at 10W with a 450W amp and literally COULD NOT get it to fail. So some of that will be the design of the driver, materials, what is being played, etc... AND what the amp is doing because there was likely no clipping going on.

I crank that little 30W amp and at some point in the volume range it becomes clear that the volume no longer increases and I don't try to push it beyond that. The point at which it starts to do that is already more than enough to fill the room with sound though, so it was really just me trying to find that point at which it occurs.

thanks a loot for the answers

is for a pc and my xbox. 360 i dont know much but maybe the avr is more expensive than a regular amp ? , maybe i can get more power from an amp for the price than a AVR?
what do you recomend? , a good AVR for 100$ ? point me to one .
brand new plz if used ill look for it in ebay XD

The reason you go with a receiver is generally because it handles a lot of different things in one box, like audio (analog and digital), video, speaker settings and calibrations, etc... So more expensive, but does a lot of stuff you won't get with just an amp. For just a straight 2speaker setup, an integrated amp along the lines of the Pyle should work. I'd also look at this one though:

http://www.parts-express.com/pe/showdetl.cfm?partnumber=310-310

Pyle says 40W @ 4ohms 10% distortion, which means to me 40W is optimistic, but still adequate for a small room and those BS22s. The one above should give about the same real world output in a more solid unit.

 

[Goliath]

I think there are a lot of factors that will come into play there as your example is not quite correct. I've driven a tiny speaker rated at 10W with a 450W amp and literally COULD NOT get it to fail. So some of that will be the design of the driver, materials, what is being played, etc... AND what the amp is doing because there was likely no clipping going on.

Speakers can't handle unlimited power. Voice-coils have thermal limits. You can't just keep on increasing the power indefinitely.

Let's make this short and sweet - there is no physical way a speaker rated to handle 10W (of that 10W, let's assume 2W for the tweeter) could withstand 100W at full rated output for an extended period let alone 450W, so I have to assume there are some details missing from that experiment. Power is what does the damage, not distortion. The additional harmonics from clipping result in a slight increase in power, not enough to cause failure.

Again, I can't believe your story has any truth to it. All speakers will fail if power exceeds the thermal limits and a 10W speaker cannot handle 450W at full rated output. Not physically possible in any way, shape or form.

 

[j_garcia]

Speakers can't handle unlimited power. Voice-coils have thermal limits. You can't just keep on increasing the power indefinitely.

Let's make this short and sweet - there is no physical way a speaker rated to handle 10W (of that 10W, let's assume 2W for the tweeter) could withstand 100W at full rated output for an extended period let alone 450W, so I have to assume there are some details missing from that experiment. Power is what does the damage, not distortion. The additional harmonics from clipping result in a slight increase in power, not enough to cause failure.

Again, I can't believe your story has any truth to it. All speakers will fail if power exceeds the thermal limits and a 10W speaker cannot handle 450W at full rated output. Not physically possible in any way, shape or form.

I was just messing around with the amp and that small 3" driver I believe. Amp was actually rated for 100W @ 8 Ohms, 450 peak, bridged though I only ran it through one channel. I expected that driver to fry instantly and for whatever reason, and this shall short and sweet also: IT DIDN'T, much to my amazement. You can question it all you like, but you weren't there. I was tossing the driver in the garbage so I figured I'd do that little experiment just to see what it would do and I was befuddled by the results. No x-over, no cabinet, just the bare driver.

 

[Goliath]

I expected that driver to fry instantly and for whatever reason, and this shall short and sweet also: IT DIDN'T, much to my amazement. You can question it all you like, but you weren't there. I was tossing the driver in the garbage so I figured I'd do that little experiment just to see what it would do and I was befuddled by the results. No x-over, no cabinet, just the bare driver.

So you are telling me your little 3" driver broke the laws of physics. Without an x-over either. Even more mind boggling. Keep that little 3" driver and I'm sure you'll be famous. People will want to know who designed and built it!

 

[j_garcia]

So you are telling me your little 3" driver broke the laws of physics. Without an x-over either. Even more mind boggling. Keep that little 3" driver and I'm sure you'll be famous. People will want to know who designed and built it!

Was a few years ago and it still went in the garbage shortly after.

 

[newton75]

thanks for your answers im learning a lot . investigated a bit a bout class T amp and seems to be the best tech . im reading only good things about it

so T class amp is the best 100 $ amp for my
Pioneer SP-BS22?
i was also checking a lepai amp that uses the same tech and cost a lot less

 

[Ampdog]

A point not mentioned is that acceptability of an amplifier is also dependant on the type of distortion. It has become acceptable to simply compare t.h.d. distortion figures, but it is necessary to know the composition of the distortion, particularly regarding high order harmonic artifacts. It is known that an amplifier boasting 0,03% THD can result in greater listener fatigue than a 0,4% model. (Subject treated elsewhere.)

On the subject of heat-dissipating ability of drivers, I will not join the present debate; as said I was not there. It has simply been shown that applying 100W of continuous sine wave power to a 100W rated driver, fried it within not too many minutes. (Some labs had the necessary funds for such a destructive operation.)

 

[PENG]

It is known that an amplifier boasting 0,03% THD can result in greater listener fatigue than a 0,4% model. (Subject treated elsewhere.)

You are of course theoretically correct, but practically speaking, not if that 0.03% is THD+N over the spectrum of 20-20,000 Hz. Total is total, regardless of the order of the harmonics so even if it has more higher order harmonics. If the total is 0.03%, each of those higher order ones will be less than 0.03% because the invidual has to be less than the total.

0.03% at any order of harmonics within the 20-20,000 Hz is only audible to golden ears. Yes, there are other distortions unrelated to the music signals (such as crossover, intermodulation etc.) but I would think most amps including the low cost EMOs got that beat already, just ask EMO..

I do agree it is possible that certain below audible level distortions could cause long term listening fatigue (Irvrobinson also mentioned that more than once) but it is hard to prove and sort out the root cause of such fatigue. For example, try listening to some of Adele's albums, I love her songs, but find it hard to endure her distorted voice at the end of a verse when she ramps up in loudness and tone. I can only attribute that to the way her albums were recorded, including mike related issues. My point is, in long term listening related issues, it is hard to just blame the amp, it could be other things causing the fatigue.