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shopping for a new receiver
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game0524
Newbie
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15. October 2009 @ 18:59 |
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I am looking for a new receiver. I currently have a sony str-k84op
I am looking at the Yamaha - 525W 5.1-Ch. A/V Home Theater Receiver
Model: RX-V465
Can someone shed some light if I am making the right choice
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Senior Member
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15. October 2009 @ 23:38 |
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That model Yamaha looks like it should be a good choice. I had a Yamaha awhile back. It was the HTR-5940. It was pretty decent for a cheap receiver. It was 6.1, had plenty of inputs, and sounded good. But then I got my Onkyo. I like my Onkyo much better, personally. My Yamaha didn't decode the new HD audio, but didn't matter at the time. I didn't have a BD player anyway. I didn't like the amber light in the receiver window. I heard the new Yamahas don't use the amber light anymore. Mine also didn't do an OSD (on screen display). Had to read everything in the tiny window of the receiver. I hated that! Looks like the 465 don't have it either. Maybe it won't bother you as much as it did me. Other than that, it looks like a great little receiver.
Good luck!
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AfterDawn Addict
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26. October 2009 @ 02:16 |
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I too am a big fan of Onkyo. I've had mine for over five years now and it has never let me down. Over the years I also have had receivers from Sony, Yamaha, and Denon. All four of those manufacturers make good quality products, but Onkyo would be my first choice.
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AfterDawn Addict
1 product review
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26. October 2009 @ 04:21 |
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Before purchasing your new rig, may I suggest finding out the type of amplifier is in the receiver (this may take a call to the customer service dept of the manufacturer)
I prefer class A/AB or AB alone
Unfortunately many receivers (nowadays) are made with some variant of class D, which I am not fond of.
I believe djscoop would agree
"The flimsier the product,the higher the price"
Ferengi 82nd rule of aqusition
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AfterDawn Addict
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28. October 2009 @ 00:58 |
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yeah absolutely check the specs before dropping down money on a receiver. class A and B are good circuits. Class D was originally used in automobile amps, and are slowly finding their way into home systems because they are less expensive.
I'm pretty sure that most higher end manufacturers like Harmon/Kardon, Onkyo, Yamaha, and Carver still use class A or B circuitry, but make sure before you buy.
Good point iluvendo, I didn't think about that...
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error5
Senior Member
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28. October 2009 @ 20:44 |
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http://stason.org/TULARC/entertainment/a...What-is-Cl.html
Quote:
The biggest disadvantage of Class A is that it is inefficient,
ie: it takes a very large Class A amplifier to deliver 50
watts, and that amplifier uses lots of electricity and gets
very hot.
Some high-end amplifiers are Class A, but true Class A only
accounts for perhaps 10% of the small high-end market and none
of the middle or lower-end market.
To get true Class A you will have to spend a small fortune.
Quote:
Class B amplifiers have a major disadvantage: very audible
distortion with small signals. This distortion can be so bad
that it is objectionable even with large signals. This
distortion is called crossover distortion, because it occurs at
the point when the output stage crosses between sourcing and
sinking current. There are almost no Class B amplifiers on the
market today.
Well well.
Quote:
Obviously, then, Class D amplifiers are more efficient than
Class A, Class AB, or Class B. Some Class D amplifiers have
>80% efficiency at full power. Class D amplifiers can also have
low distortion, although theoretically not as good as Class AB
or Class A.
To make a very good full-range Class D amplifier, the switching
frequency must be well above 40kHz. Also, the amplifier must be
followed by a very good low-pass filter that will remove all of
the switching noise without causing power loss, phase-shift, or
distortion. Unfortunately, high switching frequency also means
significant switching power dissipation. It also means that the
chances of radiated noise (which might get into a tuner or
phono cartridge) is much higher. If the switching frequency is
high enough, then less filtering is required. As technology
improves, industry is be able to make higher switching
frequency amplifiers which require less low-pass filtering.
Eventually, Class D amplifier quality could catch up with Class
A amplifiers. Some believe that it already has.
Panasonic PT-AE3000 1080p Projector//Carada 110" Criterion High Contrast Grey 16:9 Screen//Oppo BDP-83SE//Toshiba HD-XA2
Classe SSP800 Processor//Classe CA-5200 5 Channel Amplifier//Classe CA-2200 2 Channel Amplifier
Bowers & Wilkins 802D L-R/HTM 1D Center/SCMS Surrounds/JL Audio Fathom f113 x 2
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Toshibot
Member
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28. October 2009 @ 21:45 |
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Originally posted by error5:
http://stason.org/TULARC/entertainment/audio/general/11-18-What-is-Amplifier-Class-A-What-is-Class-B-What-is-Cl.html
Quote:
As technology
improves, industry is be able to make higher switching
frequency amplifiers which require less low-pass filtering.
Eventually, Class D amplifier quality could catch up with Class
A amplifiers. Some believe that it already has.
Most receivers and power amps are class AB but i don't think you'll hear too much difference with a Class D especially if you have low to mid level speakers.
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error5
Senior Member
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29. October 2009 @ 08:14 |
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Originally posted by Toshibot:
Most receivers and power amps are class AB but i don't think you'll hear too much difference with a Class D especially if you have low to mid level speakers.
From the article:
Quote:
Class AB amplifiers are almost the same as Class B amplifiers
in that they have two driven transistors. However, Class AB
amplifiers differ from Class B amplifiers in that they have a
small idle current flowing from positive supply to negative
supply even when there is no input signal. This idle current
slightly increases power consumption, but does not increase it
anywhere near as much as Class A. This idle current also
corrects almost all of the nonlinearity associated with
crossover distortion. These amplifiers are called Class AB
rather than Class A because with large signals, they behave
like Class B amplifiers, but with small signals, they behave
like Class A amplifiers. Most amplifiers on the market are
Class AB.
You are correct in your comment about the speakers. True Class A amps are likely out of reach for the regular consumer and can only be found in 10% of the high end market. Pure Class B amps are nonexistent so most amps are sort of "hybrid" Class AB. Like the article said Class D amps may have already caught up in quality. To the untrained ear and with low to mid level speakers one may not even hear a difference.
Plus Class D amps draw less power and are thus more environmentally friendly. You lower you carbon footprint - if you're into that sort of thing.
Panasonic PT-AE3000 1080p Projector//Carada 110" Criterion High Contrast Grey 16:9 Screen//Oppo BDP-83SE//Toshiba HD-XA2
Classe SSP800 Processor//Classe CA-5200 5 Channel Amplifier//Classe CA-2200 2 Channel Amplifier
Bowers & Wilkins 802D L-R/HTM 1D Center/SCMS Surrounds/JL Audio Fathom f113 x 2
This message has been edited since posting. Last time this message was edited on 29. October 2009 @ 08:28
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AfterDawn Addict
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2. November 2009 @ 03:22 |
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there are really high end amps that do use class A circuits, McIntosh is one I believe.
We've been talking about different amp class circuits recently on another thread about subwoofers, so its funny this topic came up again. I definitely recommend a AB class amp over a class D amp. Here is what I posted earlier today on the other thread about the classes:
The class D amplifiers are much more energy efficient. Class A and AB circuits are very inefficient. only 10 to 20 percent of its power consumption is actual signal output, the rest is heat. Class D circuits use a different type of transistors. I won't bore you guys with the super technical details, but basically class D transistors are either on or off. when they are on, the current draw is at the max but voltage is zero. when they are off, the current is zero but the voltage is at max. basically that means that a minimum amount of current is drawn when the transistors require a large load, and vice versa.
the downside of class D circuitry is that signal quality is much less than that of other classes of amplifiers. They implement pulse width modification to convert the input signal to a sequence of pulses which makes the transistors as efficient as they are.
Quote:
Eventually, Class D amplifier quality could catch up with Class
A amplifiers. Some believe that it already has.
I would have to disagree. There is a very good reason why the majority of the class D amplifier circuits are still used only in subwoofer amps and car audio. The quality just still isn't there compared to the A and AB classes. Perhaps one day when the different processes it uses to convert the signals and sequence the push pull effect improve, then there will definitely be a good competition between class AB and class D.
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error5
Senior Member
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2. November 2009 @ 08:21 |
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Originally posted by djscoop:
Perhaps one day when the different processes it uses to convert the signals and sequence the push pull effect improve, then there will definitely be a good competition between class AB and class D.
I guess that day is already here with the Rotel RSX-1560 Receiver.
Quote:
Throughout my listening sessions, I wondered if Rotel had really pulled an audiophile rabbit out of the Class D hat. My movie demos suggested that the answer might be yes. But the music demos were more conclusive.
Orchestral strings are among the toughest listening tests. The violin has an inherently nasty sound?but if you put a bunch of them in a great hall, record them well, and play them back through a great system, you should be as near to heaven as human life allows. For this test I picked a vinyl edition of Bernard Herrmann conducting the National Philharmonic Orchestra in Music From Great Shakespeare Films, works written for Hamlet, Richard III, and Julius Caesar by Shostakovich, Walton, and Rózsa. Those old London Phase 4 LPs could sound fabulous. Violins: yes, with the right feel. Cellos: dark and chocolatey, another yes. Basses: surprisingly full and tuneful, another yes. This was a fully developed string sound, not a tizzy facsimile or dumbed-down fake.
Only with the most metallic instruments?some brass and a relentlessly shaken tambourine?did I detect a difference between Rotel?s Class D sound and its Class AB sound, which I know and love so well. It was a tiny difference in flavor and had nothing to do with discomfort. It was more like looking at the Mona Lisa under incandescent light and then looking at it again under a high-quality compact fluorescent with the same lumens and color temp. Same painting, same colors, slightly different light.
You?ll laugh, but let the record show that my appreciation for the RSX-1560 was considerably heightened when, while flipping the Herrmann LP, I treated myself to a Guinness. Once I stopped fretting, the Rotel sounded much better. I did all the other demos sober (my normal practice, of course), but I thought this might be worth noting. If you get all uptight about listening to anything, you listen differently, and perhaps not as well.
Richard & Linda Thompson?s Hokey Pokey is their best-recorded album. Using the Universal/Island CD re-release, I enjoyed a solid drum sound with pleasing mid-bass fullness. Linda?s emotionally potent soprano is like a canary in a coal mine. It has a strong treble content and is hardwired into my heart. This receiver didn?t make me turn her down, and I listened at a high volume level suitable for foreground listening. When I switched between the Dolby Pro Logic II Music mode and stereo, I preferred the former for the way it highlighted the layering of voices and guitars, with better separation of harmony vocals.
Dave Frishberg?s Songbook Volume 1 is yet another of my sidewalk LPs. The Rotel lovingly projected the comic jazz singer?s slightly nasal voice. His piano, which is recorded close up, sounded as if it were in the room with me. The string bass and light drums were pitch-perfect. With this highly natural recording, stereo was the only way to go?DPLII actually bent the soundstage out of shape in an obvious way, which surprised me, because that rarely happens. The difference between this pristine piece of vinyl and the CD release of Frishberg?s Classics?which contains many of the same songs?was night and day. The LP has far more vivid textures and increased spatiality. Audiophiles and people who run trade-show demos should track down this piece of wax and put it in heavy rotation. By the time I was done with it, I was convinced that I was listening to a great receiver, one that deserves a spot on our Top Picks list.
The Rotel RSX-1560 is not just a science experiment in Class D amplification. It is a fine-tuned product that maintains the manufacturer?s effortlessly musical personality while projecting it onto a new amplifier topology. If I agonized over this receiver, I can only imagine how many sleepless nights Rotel?s designers spent trying to make it sound as good as its shiny front panel looks. With Mother Nature giving us dirty looks, it?s nice to know that such a thing is possible.
http://www.hometheatermag.com/receivers/...ver/index2.html
I got a chance to listen to the 1560 driving a pair of B&W series 7's and I must say I agree with the review.
Panasonic PT-AE3000 1080p Projector//Carada 110" Criterion High Contrast Grey 16:9 Screen//Oppo BDP-83SE//Toshiba HD-XA2
Classe SSP800 Processor//Classe CA-5200 5 Channel Amplifier//Classe CA-2200 2 Channel Amplifier
Bowers & Wilkins 802D L-R/HTM 1D Center/SCMS Surrounds/JL Audio Fathom f113 x 2
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AfterDawn Addict
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2. November 2009 @ 14:34 |
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I'm sure the rotel sounds great, but that wasn't the point I was trying to make. The rotel is almost a $3000 receiver. Of course any receiver of that build quality and price is going to sound good. if not, no one would buy it.
the fact that it takes a high end company to build a $3000 receiver to be able to say that the class D circuitry sounds good it pointless. To me, that means its still not readily available on a consumer level. When companies like Sony, Denon, and Onkyo can produce class D receivers for the same price as the AB ones, but have the same quality, thats when the technology will be here.
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AfterDawn Addict
1 product review
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17. November 2009 @ 02:56 |
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Although the article is somewhat dated, the basic electrical engineering design principles are still valid.
The limitations of Class D
If Class D were perfect, it would have swept the world and there would be no other class in common usage. I'll tell you about the three major problems of Class-D amplifiers in a moment, but first, here's a question: how do you make an efficient radio transmitter? Answer: start with a Class-D audio amplifier. Yes, the high frequencies involved in Class-D amplification readily propagate as radio waves, potentially causing interference with radio receivers and other equipment. You might think that the solution would be to enclose the amplifier in a substantial steel housing. But that's not where the problem manifests itself ? it's in the cables. The filter that is supposed to remove the high-frequency components and leave only the audio signal is quite shallow in slope ? 6dB or 12dB per octave ? so there's quite a lot of RF energy still getting out. Clearly, manufacturers take care to improve the situation and remain within allowable limits, but it is a problem inherent to Class D.
The second problem of Class-D is that the last thing the signal sees before it reaches the loudspeaker is the filter. A passive filter made from capacitors and inductors expects to see a certain load on its output. Even just looking at the resistance of a loudspeaker and ignoring its capacitance and inductance, loudspeakers come in 2(omega), 4(omega) and 8(omega) nominal impedances, and the filter will work differently according to the impedance of the loudspeaker. Taking capacitance and inductance into account, the impedance will vary according to frequency. So the filter design is suddenly very much more complex: an amplifier that performs differently for different speakers is going to be a problem.
Thirdly ? not finally, but enough for now ? a Class-D amplifier has a relatively poor damping factor. The damping factor is the ratio of the impedance of the loudspeaker to the output impedance of the amplifier (it's a little more complex than that, but let's not get bogged down with details). In simple terms, it's a measure of how well the amplifier can control the movement of the diaphragm of the loudspeaker. A good amplifier doesn't just give it a push and hope for the best; it senses where the diaphragm is from moment to moment and controls its position. To do that, a high damping factor is desirable, and, as mentioned above, a simple Class-D amplifier has a low damping factor.
Clearly, advanced technology can be applied to ameliorate these problems, but because of them Class-D amplification is used mainly in applications where efficiency, weight and small size are important. These include live sound, in-car audio and compact portable systems.
Top of page
That's not all, folks
Clearly, there is more to know. For instance, it's important to know that the switching frequency must be very high to achieve the necessary resolution. A switching frequency of around 300kHz, which is around 15 times the highest audio frequency of general interest, is typical. The dynamic range and signal-to-noise ratio of the Class-D amplifier are controlled by the switching frequency ? the higher the better. Clearly, the greater the rate of pulse generation, the more closely the pulse width will be in proportion to the instantaneous signal level. However, the drawback of increasing the switching frequency is that the amplifier will be less efficient. Optimum efficiency would be achieved if the transistors could switch instantaneously, so that they were in either their fully on or fully off states, where almost no power is consumed. But in the real world it takes a little time for the voltage to swing, and during that time some power is dissipated. So the more often the swings take place, the more opportunity for waste. Even so, the efficiency of a practical Class-D amplifier can be better than 90 percent, which is significantly better than a Class-AB design (78.5 percent at best and typically closer to 50 percent).
Coming full circle, because a Class-D amplifier is more efficient than the conventional Class-AB one, it can be lighter. And that, in a nutshell, is the reason for Class D's existence. Lighter also leads to smaller, and to achieve the high switching speeds necessary, the circuitry has to be physically small. Look inside a Class-D amplifier and you'll find a transformer. Look hard enough and somewhere in there you'll find the circuit too!
http://www.google.com/url?sa=t&source=we...yVW-fQumUOCjgNQ
"The flimsier the product,the higher the price"
Ferengi 82nd rule of aqusition
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