Will this be enough for my room? [Archive] - Audio & Video Forums


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05-08-2008, 03:55 PM
:smile5: The specs for my living room is 18x22 with vaulted ceilings. I am not sure if my below anticipated set-up will be enough to fill out my room espeically with the vaulted ceilings.

Intially I was set on the Onkyo 705, but have decided to get the Onkyo 805 due to the extra power it provides. For my floor speakers, I will probably be going with the B&W 683, NHT Classic 4's or the Monitor RS6. I will be matching the centers of course with which ever company my mains are from....along with the surrounds. The sub of my choice will probably be a SVS PB-12 Plus.

I will not be buying an amp now and may buy one in the furture if needed.

Do you guys with expereince feel as if this is going to give me a strong full sound in a large room or do I need to go bigger and spend more $$$$$ I am not the kind of guy that is going to BLAST my music at obscene volumes, but I'd like for it to rock the house if needed!

Let me know


05-08-2008, 06:29 PM

You have a good size room there especially with vaulted ceilings. The B&W 683's will do it it my opinion as your L&R mains since they're designed for large rooms. I'd go with the subwoofer that is recommended by B&W for the 683's. Be careful about the specs on the Onkyo 805. Are you sure that the 130 watts into 8 ohms is achieved with ALL CHANNELS DRIVEN or two channels driven?

Manufactures like Rotel and NAD specify all channels driven but most don't and you can be easily mislead. I just looked at the Onkyo website for the 805 and I see 2 channels driven included in the specs but I'm still not sure. I would call them directly on this. You may think you're getting 130 watts when you're driving your 5.1 or 7.1 system when in reality you're only achieveing a certain percentage. Marantz for example guarantees only 70% of the rated power when driving all channels. When driving only 2, then yes you get the full amount specified. This has been one of my pet peeves for a while now.

I would also highly recommend you install thick carpet on your floor in this room. The vaulted ceilings are going to cause echoes and you'll need some good bass traps. Enjoy.

05-08-2008, 11:40 PM
Well, the SVS PB-12 Plus at about $1000 is a monster! There is nothing in the B&W line at any where near this price that can even begin to touch the performance of this SVS sub. In a review in the Secrets of Home Theater & Hi-Fi by Ed Mullen he tested the PB-12 Plus to measure from 14Hz - 100Hz at +/- 1.5dB's! It produced 99-100dB's in the 16-18Hz range! This is simply amazing performance for a $1000 sub let alone any price range. He felt it was excellent for both HT and music. It's big and it will rock your house. It might even move it several inches towards your neighbor's house.

The Onkyo 805 will give you about 30 more watts per channel over the 705. If you understand the relation between power and sound output you will know that this is less than a 1 dB increase in volume. That will give you only a very slight amount of additional headroom. However, with the higher THX Ultra 2 certification and any other features in the 805 then the additional $150 or so might be worth it to you.

BTW, yes both are rated at 20-20,000Hz with both channels driven into 8 ohms at 0.05 and 0.08% (130 watts for the 805). This is normal to rate this way. Some brands only give you a one channel or rating only at 1kHz. Onkyo also gives a dynamic/peak rating into 8, 4 and 3 ohms. These are excellent amps in this price range. The all channels driven (ACD) ratings are very seldom listed by manufacturers and are almost never necessary in actual music or HT power demands. It is extremely rare that an amp would be required to deliver equally high amounts of power in all 5 or 7 channels. A high ACD power output would be indicative of a solid amp but not necessarily important in a real world application.

In fact Rotel plays a little trick here. It is important for high end dealers to convince their customers that their receivers are better than the common mass marketing outlet revceivers like Onkyo, Yamaha, Denon, etc. They list their amp at power into 5 channels driven and the dealers say this rating shows that their amp is better. But look down their spec sheet at the ratings into two channels which they list at 1kHz. The Onkyo 805 actually specs out at 150 watts at this same rating that the Rotel specs out at 100 watts. Note that the Rotel sells for about $400 more.

Rotel Model RSX-1057
Continuous Amplifier Power
(Five channels driven) 75 watts/ch (20-20k Hz, <0.05% THD, 8 ohms)
Continuous Amplifier Power
(two channels driven) 100 watts/ch (1kHz, <1.0% THD, 8 ohms, DIN)

Onkyo TX-SR805
130 W + 130 W (8 ohms, 20 Hz–20 kHz,
0.05%, 2 channels driven, FTC)
150 W + 150 W (8 ohms, 1 kHz, 0.7%,
2 channels driven, FTC)

Sound and Vision tested the Onkyo TX-SR875 which is rated at 160 watts into two channels at 1kHz (the same criteria as the 805 rated at 150 watts). S&V actually tested the 875 at 141 watts with 5 channels driven and 128 watts with 7 channels driven. This is impressive power output for this class of receiver. I would estimate that the 805 might produce 132 watts unto 5 channels and 120 watts into 7 channels. I would further estimate that the 805 would produce about 112 watts into 5 channels at 20-20,000Hz at 8ohms/.05% (versus 75 watts for the Rotel). The Onkyo 805 weighs about 13lbs more than the Rotel 1057. (Now someone will say that the Rotel sounds better) (Sorry, I just don't have time to do this with the NAD, ha!).

Test reviews that I read show tha the B&W 683 actually has about a 86dB sensitivty rating and about an 89dB rating for the Monitor Audio RS6 (my 2 choices of the above 3 speakers). The B&W tested slightly lower in the lowest impedence. It would seem that the RS6 might tend to be about 2dB's louder with the same Onkyo. I think both would be plenty loud for your room and likes. I would recommend setting your sub crossover at 80Hz and do not put the Onkyo impedence switch at 4 ohms. Expect the Onkyo to run fairly warm.

Best of luck on your final choice.


05-09-2008, 03:59 AM
Road Runner touched on this a bit on this already, but you guys really shouldn't get too hung up on the All-Channels driven specification - I know a lot of spec-jockeys are really keen on this figure still, but it's a pretty unrealistic way of comparing the real world performance of a receiver's power supply. It's another clever marketing trick some companies use, a different approach than the high distortion, low impedance power ratings, but misleading all the same.

You will find very, very few movies where maximum gain to all channels is sent consistently, for an extended period of time that equates to the all-channels driven tests. Instead, it's usually a blend of most of the gain going to the front 3 speakers in short bursts (allowing for recharge in between) and less gain going to the surrounds when applied. THX has done extensive testing on movie soundtrack patterns, and the most they'll check for in their standards is to see if an amp can sustain the voltage swing required to drive a few channels simultaneously for just a few seconds. Never 5 or 7 channels at max for more than a few seconds. In many cases, a an amplifier will deliver more power to 2 or 3 channels (ie in stereo mode) than another amp, but then fail to deliver the same power with all 7 channels driven. Which amp is more powerful? The one that gives more maximum output in real world (movie, stereo music) scenarios, or the one that can play a sine wave a bit louder in a laboratory with all channels driven?

The big Onkyo 805 has a healthy 875 watt power supply. That's the most that thing can suck from the wall without frying. That Rotel has a respectable 450 watt power supply unit. This should tell you all you need to know about which has more real world power capability.

That doesn't speak to the sound quality of the amplifiers themselves though, only their ability to not further distort the sound quality they are capable of achieving at high levels.

As a receiver solution, I would think the 805 would be sufficient for the 18 x 22 room size, though perhaps the lower sensitivity of the B&W's might be problematic.

05-09-2008, 06:06 AM
I realize how important it is to properly prep a room for quality sound, but this simply is not practical in my case. The house that I am building has all hardwood floors and putting carpet in the entire living room would honestly ruin the open look of the floor plan. That would be a great recommendation if it was doable!

I am entirely new to the audio world so some of the technical things you guys are talking about are really going over my head! I was surprised to find out that the additional 30 watts I would be getting from the 805 would result in only a 1dB increase! What is the benefit of the extra 30 watts? Is there any benefit in the 705 over the 805? Would the extra wattage result in a cleaner sound when the speakers are being driven hard vs driving them at the same dB level with lesser wattage?

I looked at the stats that I was provided by roadrunner since the stats on the website differed. The 683 has a sensitivity of 86dB vs the RS6's 89dB. Does this statement determine that the Monitor speakers are more efficient and that they will be 2dB louder? Is 2dB louder even worth making such a decision over?

05-09-2008, 06:49 AM
The 805 is more powerful. The 705 might have enough power for your needs. Hard to say without knowing what speakers you're using, what volumes you typically play at. Do you listen to 2-channel music more than you watch movies in surround sound?
The difference in power isn't much, but it is very possible that it's a difference between just enough, and not enough power. The 805 is a slightly better amplifier in terms of distorition, signal-to-noise etc. It should sound incrementally better.

Remember, music is dynamic - lots of short term peaks or bursts of energy. You will hear distortion as you exceed an amplifiers capabilities. Trying to predict what point that is going to be in your room is no easy task. But even with 86 dB speakers, the 705 will play pretty darn loud. I don't think you'll have problems hitting 95 dB peaks in your room even sitting 10 feet away from your speakers, which puts you at THX certified theater levels. That's pretty loud, a lot more power than most home theaters would have.

As for the 2-3 dB sensitivity differnece - it's not insubstantial. One thing you might consider - a lot of B&W's are a bit more difficult to drive because of slightly lower than normal impedance dips. They're not worse speakers, they just like current. You might appreciate the extra power and current of the bigger receiver if you decide to go with B&W.

05-09-2008, 07:21 AM
kexodusc, I just wanted to tell you thanks for your awesome reply. You made it almost crystal clear and thats pretty darn difficult when talking to a noob!

I will be using the system for mostly HT, but will be using it a lot too for music (60% HT, 40% music). I am not the one to crank it up as far as it will go, but I cannot stand music played quiet or even at average volumes. I enjoy being able to hear my music extremely clear and borderline loud, but definately not very loud.....if that makes sense!

I am going for my final audition (I hope) next Friday and hopefully I would have at least decided what mains I like best. Obviously sensitivity is not the sole determinator of which speaker works best otherwise all speakers would have extremely high sensitivity. I simply do not understand why some speaker companies choose to go down certain avenues to produce sound. That is obviously because I do not understand different philosophies that certain companies use to produce what the think is the "best sound". Why 8ohm vs 4ohm and why lower sensitivity than others etc?

05-09-2008, 04:46 PM
Onkyo, Denon, Yamaha, etc are mass market A-V receivers. Rotel is not. You get what you pay for. That's why Rotel is $400.00 more as stated above. I'd much rather have 75 watts x 5 all channels driven conservately than 130 watts x 5 from a mass market receiver. It's not just watts by a long shot. It's the quality of the components and design that goes into the unit, the power supply, the care in manufacturing, etc. Rotel advertises with total honesty and does not try to mislead. We comparing apples and oranges here. There is no comparison !!