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Amplifier FAQ - Page 2

post #31 of 227
Thread Starter 
Right. Only questions/comments addressing the FAQ itself should be posted here. I don't mind answering general amp questions here, but it's probably more effective to create a new thread for questions.
post #32 of 227
Excellent post; very informative. Thanks.
post #33 of 227
MichaelJHuman,

Great post! Well done.

Helps us lost little fuzzballs in the big bad world of pretty boxes.

Thanks,
Mike K
post #34 of 227
Hi All,
I'm quite confused about what to do.I have a Yamaha rxv-1900,while it is fantastic for movies,for 2 channel music,it is very ordinary.So i am going to add an amplifier to it,either a 2 channel power amp or an integrated amp.I don't know which is the better way to go,a power amp i think make more sense,but i'm thinking i could still end up hearing the Yamaha through it,where-as if i get an integrated,i know i will totally eliminate the Yamaha sound,which is what i'm wanting to do.Any suggestions? And any recommendations on what brand around the $1,500 range.
post #35 of 227
Thread Starter 
Post this as a separate thread, and I or someone else can help you there (posts to this thread should be related to the FAQ, please - and you will get more help with a post to the forum.)
post #36 of 227
MJ,

I thought SLEW RATE was important spec for dynamic transient reproduction and DAMPING FACTOR was import for LFE reproduction.

Mike
post #37 of 227
Here is a good tech Doc on Dampening.

http://www.diyspeakers.net/Articles/...G%20FACTOR.pdf
post #38 of 227
Thread Starter 
Quote:
Originally Posted by mmiles View Post

MJ,

I thought SLEW RATE was important spec for dynamic transient reproduction and DAMPING FACTOR was import for LFE reproduction.

Mike

Slew rate is import for HF, not LFE. This is pretty logical if you think about it.

With a low frequency signal, the voltage amplifier stage of the amp does not have to be very fast. With increasing frequency to the VAS, the slew rate has to be higher to avoid distortion.

From what I have read, most amps have more than enough slew rate, making the discussion of slew rate uninteresting, perhaps.

There's a nomograph (I think it's called,) showing relationship between frequency and slew rate at Rod Elliott's site.

I think Penn covered damping factor above There's at least three articles explain how damping factor is overhyped online. In both amp design books I own, both authors downplay for all the reasons you can read online.
post #39 of 227
Great help thanks. What about a FAQ concerning pre-amps, what they are, pro's con's etc?

Just a thought.
post #40 of 227
Thread Starter 
Quote:
Originally Posted by Knd View Post

Great help thanks. What about a FAQ concerning pre-amps, what they are, pro's con's etc?

Just a thought.

Stereo pre amps or AV processors? There's not much I could add about AV processors that I did not cover in the AVR FAQ.

Stereo pre amps are simple pieces of equipment with a source selector and a volume control. I am not sure what I could say about that...
post #41 of 227
It always seems that when people compare amplifier sound quality they refer back to these blind A/B tests. Some of these reports “want” to show that there is little difference between amplifiers so in these tests, they usually limit the output to below clipping of the weakest amp then balance the output of the amps. To me, this is not comparing apples to apples. I agree that it shows the amps are similar at that give test criteria but that has little to do in the real world. I think how these should be tested is at different SLP levels with no limits. This is where you will see the more powerful amps pull away from the weaker ones. I found this out when I bought my first Pioneer Elite receiver. I thought I could pull my Carver amps out of my system but after A/B testing them at different SPL levels, I opted to keep the amps and run the Pioneer as a Pre/Pro. The Pioneer played as loud but not as good as the Carvers.
The second thing that should be mentioned is the power supply of amps. When an amps 4 ohm rating is less than double that of it’s 8 ohm rating, it’s an indication of a smaller than ideal power supply for the amps rated output. As an example amp A is rated at 200w@8 ohms/300w@4 ohms while amp B is rated at 300w@8 ohms/600w@4 ohms. This indicates that amp B has a better sized power supply to it’s rated output. I haven’t seen any reports on this but I would tend to believe this lack of power would increase the clipping when the amp is under heavy load. Maybe someone with more knowledge on this subject could add more to this power supply discussion.
post #42 of 227
Thread Starter 
I agree with some of what you said, but you may be a bit off base on the doubling down aspect. A number of engineers have stated that few amps will truly double power when the impedance is halved.

Some have even claimed that some manufacturers will de-rate their 8 ohm output just so it looks like the power doubles. In other words, even if the manufacture specs should power doubling into 4 ohms, that's because the 8 ohm power rating was doctored (while I can't prove this, I have seen it mentioned a few times, and I would not put it past manufacturers.)

I don't fully understand the technical reasons, but I would guess there are losses which make doubling power into half the load a difficult problem.

Seems to me that if the amp comes pretty close to doubling power into 4 ohms, it's a good amp. I don't think it has to do it exactly for it to be considered a good amp.
post #43 of 227
Quote:
Originally Posted by MichaelJHuman View Post

Slew rate is import for HF, not LFE. This is pretty logical if you think about it.

With a low frequency signal, the voltage amplifier stage of the amp does not have to be very fast. With increasing frequency to the VAS, the slew rate has to be higher to avoid distortion.

From what I have read, most amps have more than enough slew rate, making the discussion of slew rate uninteresting, perhaps.

There's a nomograph (I think it's called,) showing relationship between frequency and slew rate at Rod Elliott's site.

I think Penn covered damping factor above There's at least three articles explain how damping factor is overhyped online. In both amp design books I own, both authors downplay for all the reasons you can read online.


I did not say SLEW was for LFE

Interesting work indeed Mr. MJ.
post #44 of 227
Thread Starter 
Quote:
Originally Posted by mmiles View Post

I did not say SLEW was for LFE

Interesting work indeed Mr. MJ.

Good point, I misread your post a bit, sorry.
post #45 of 227
Thanks much for taking the time to put this together! I am looking for an amp but not sure where to start - this is really helpful for a noob like me.

I have had Yamaha RX-V663 and HK 3600 receivers for living room/entertainment center. I need something to drive some Ascend Sierras for music in a bedroom setup. I don't need AVR capabilities nor lots of add ons. Just looking for clean power to play music at normal, not-loud volume, that is unobtrusive (smaller than a receiver). I use itunes to the airport express with lossless files. Looking in the sub $500.00 range. I love the HK sound so something similar to that would be awesome. Anyone have any suggestions for amps to take a look at for purchase? Also, any other threads I might check out which will help me find what I am looking for?
post #46 of 227
Thread Starter 
Put up a new post on what you want. There are some options I think, but you will get more help outside this thread.

Posts to this thread should be to address the FAQ.
post #47 of 227
Not sure if I should have made a new thread.. but what are people opinions on bi-amping without a seperate amp?

Heres Onkyos take on it(RC260 manual)
Quote:


Bi-amping the Front Speakers

The FRONT L/R and SURR BACK OR FRONT HIGH OR FRONT WIDE L/R terminal posts can be used with front speakers and surround back speakers respectively, or bi-amped to provide separate tweeter and woofer feeds for a pair of front speakers that sup- port bi-amping, providing improved bass and treble per- formance.

Once you’ve completed the bi-amping connections shown below and turned on the AV receiver, you must set the “Speakers Type” setting to “Bi-Amp” to enable bi-amping (➔ 35).

In general do all modern 7.1 receivers use this feature the same way as onkyo?
post #48 of 227
Thread Starter 
Your question has been discussed many times. Try a search, and if that does not help, post a new thread.

Short answer - biamping from a receiver does not see likely to give an improvement gain as the amps all share from the same power supply. But there's no harm in trying it out, just the price of wire (which is cheap.)

Posts to this thread should be directly related to this FAQ (Maybe I need a section on bi-amping.)
post #49 of 227
Many thanks! Glad to see it stuck as this is a must read for any nube and greatly appreciated.
post #50 of 227
Thread Starter 
Quote:
Originally Posted by 2dflyer View Post
Many thanks! Glad to see it stuck as this is a must read for any nube and greatly appreciated.
Thanks
post #51 of 227
Nice read, thank you for taking the time to post the information.
post #52 of 227
Thanks for a very practical FAQ. Long overdue.
post #53 of 227
Thread Starter 
Quote:
Originally Posted by rnrgagne View Post

Thanks for a very practical FAQ. Long overdue.

Thanks, I appreciate the kind words.

I know it has typos and can be better, and it's on my to-do list. And I think it needs a section on biamping, if memory serves.
post #54 of 227
Quote:
Originally Posted by MichaelJHuman View Post

Thanks, I appreciate the kind words.

I know it has typos and can be better, and it's on my to-do list. And I think it needs a section on biamping, if memory serves.

Yeah, it's definitely in the "misunderstood" category as far as amplification goes.
post #55 of 227
Hello

I have read the FAQ in this post, very enlightening. I am considering replacing my 3 and two channel 200 watt amplifiers with a 5 channel 100 watt amp.

I have used the crown calculator from this post and have determined 20 watts are required from my seating position for 100DB.

What else should I consider for downgrading so to speak. The 100 watt 5 channel is sweet and an incredible deal. I certainly will not miss the missing 100 watts from the calculator.
post #56 of 227
Thread Starter 
Quote:
Originally Posted by kiwi2000 View Post

Hello

I have read the FAQ in this post, very enlightening. I am considering replacing my 3 and two channel 200 watt amplifiers with a 5 channel 100 watt amp.

I have used the crown calculator from this post and have determined 20 watts are required from my seating position for 100DB.

What else should I consider for downgrading so to speak. The 100 watt 5 channel is sweet and an incredible deal. I certainly will not miss the missing 100 watts from the calculator.

Your best bet is to post this question outside this thread for the best response.
post #57 of 227
As thread starter please tell me your opinion.
post #58 of 227
Thread Starter 
Post your question outside this thread, and I will Then you will get opinions other than mine as well.
post #59 of 227
I have now posted off this thread. Please give me your opinion. Thanks.
post #60 of 227
I'm looking at adding an amp to my Pioneer 1120 and was wondering about the SQ. Will the amp effect the SQ or receiver will have the most effect with SQ.
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