General question about Speakers, Watts, and A/V Receivers.

Jimbobwey

Hey guys, I'm a first time poster here in the Polk Forums and this will probably be a such a easy question for more experienced people to answer. I've spent about 2 weeks researching about a cool speaker setup for my room and eventually an apartment or home. I've been looking at purchasing the ONKYO 7.2-Channel Home Theater Receiver TX-SR608 and pair of TSi400 or TSi500 floorstanding speakers. The receiver is rated at 100W per channel @ 8 Ohms each. The speakers suggest an amplifier rating of 20-275W. Since the speakers have an efficiency of 91db...does that mean my speakers will be able to reach around 110db before they start to clip and distort?

I made this little graph to show what I'm talking about...

91db 1 watt
94db 2watt
97db 4 watt
100db 8 watt
103db 16 watt
106db 32 watt
109db 64 watt
---- (Clipping starts to occur?)
112db 128 watts
115db 256 watts

Anyways...I don't plan on listening or pushing my speakers past 110db alot of time...so will the Onkyo receiver be just fine for what I'm looking for or do I need to invest in an amplifier that is rated at about 300W per channel?

Any feedback would be greatly appreciated!

Pycroft

Jimbob -

Welcome to Club Polk. I can't answer your question regarding the clipping at what db, but I have some info. First - I would bet big money that the Onkyo Receiver is NOT 100 wpc with all channels driven. More than likely, it is well below that, which would change your calculations. It's always my suggest (Because I started like you did, with the 600 line of Onkyo) to buy a receiver with pre-outs so you can add amplification later if you want to really power your speakers.

Best of luck, and again, welcome.

James

zingo

If you are planning on driving your speakers to 110db, I would get a dedicated amplifier instead of an AVR. What kills speakers is when amplifiers clip, and besides that AVR probably not actually being 100wpc, if you have any bass or dynamics in the music, you are going to blow through that power very quickly. The bottom line is the clipping with an AVR will come well before 110db. Over powering a pair of speakers is almost never a problem and a clean, high current amp would be your best option to play either of those Polks loud.

I hope this help and welcome to CP.

Jimbobwey

Thanks for the responses guys! The only reason I was looking at an A/V receiver was for the future...instead my best bet would to buy an amplifier then an AVR when the time comes closer? When I buy an amp, would I want to buy a 2 channel for the two floorstanding speakers and then would a AVR take care of the rest of the 5 speakers when I get a 7.2 system? Sorry if these sound like noobish questions...this is my first venture into the home theater and music world

Pycroft

I would buy an AVR that has preouts - meaning you can hook up another amplifier later and not worry about changing AVR's. The Onkyo 608 does NOT have pre-outs, so if you wanted an external amp, you'd have to buy a new AVR. If you look at the 700 or 800 series from Onkyo, Harman Kardon 254/354, and others from pioneer, yamaha, etc. If you have speakers and an AVR with preouts, you can slowly build a system that will be great. The speakers will be FINE with just the AVR as long as you don't push it too hard. If you are patient, and go a little at a time, it won't be overbearing to build a great system!

Good luck!

James

Jimbobwey

When I get an amplifier, do I want to purchase a 2 channel or 7 channel...ultimately I want a 7.2 setup. I figure the floorstanding speakers are going to suck the most energy so a 2 channel would make sense but does that mess up the other 5 speakers?

BlueFox

I don't think you realize how loud 110db really is.

Jimbobwey

Chain Saw, Steel Mill, Riveting, auto horn at 1 M loud? My main concern is just that I want to be able to power my speakers loud without damaging the amp/receiver or speakers.

How well known of a brand is technical pro? I was browsing and their products are based towards dj...but the price seems resonable!

http://tpro.com/prods.php?prod=PA-3000

zingo

That amp would not be my first choice. "Pro" amps tend to be more electronically noisy than home amps, plus a lot of them have fans.

Try your local craigslist or audiogon for a proven, used home amp.

Jimbobwey

Thanks Zingo

cnh

www.audiogon.com is your friend...and mine...and....

Brands to try to listen too.....Rotel, Carver, B&K, Adcom, Parasound, NAD, Aragon, Pass Labs, and so on....

Good luck...

BTW..the Onkyo 70X series is hard to beat (feature to price ratio) for your pre/pro. But do listen...you might prefer a Pioneer or an HK, etc.

cnh

Knucklehead

Keep an eye out here as well Jimbob, deals on good AMPS can be found. Welcome to CP.

David

SoundEngine355

Jimbobwey wrote: »

Hey guys, I'm a first time poster here in the Polk Forums and this will probably be a such a easy question for more experienced people to answer. I've spent about 2 weeks researching about a cool speaker setup for my room and eventually an apartment or home. I've been looking at purchasing the ONKYO 7.2-Channel Home Theater Receiver TX-SR608 and pair of TSi400 or TSi500 floorstanding speakers. The receiver is rated at 100W per channel @ 8 Ohms each. The speakers suggest an amplifier rating of 20-275W. Since the speakers have an efficiency of 91db...does that mean my speakers will be able to reach around 110db before they start to clip and distort?

I made this little graph to show what I'm talking about...

91db 1 watt
94db 2watt
97db 4 watt
100db 8 watt
103db 16 watt
106db 32 watt
109db 64 watt
---- (Clipping starts to occur?)
112db 128 watts
115db 256 watts

Anyways...I don't plan on listening or pushing my speakers past 110db alot of time...so will the Onkyo receiver be just fine for what I'm looking for or do I need to invest in an amplifier that is rated at about 300W per channel?

Any feedback would be greatly appreciated!

110dB is very loud! You would go deaf in a short space of time!

I listen to music between 75-80dB, having the extra watts does become clear at lower volumes, true 300W/8 is overkill for the type of speaker you are talking about.

True 100W/8 is all you require, however if you want more reinforcement then 150-200W/8 would do the trick, anything over that you will not hear the difference.

If your pushing dual 10" drivers like in the B&W 800Di's then you need some serious power!

Cheers

SE

Gulfstrings

jimbobwey -

I'm just a step or so ahead in putting a system together. I took the advicee of the more experienced here and aquired an Onkyo AVR, their 707 model. It has all the functions you need for an HT and preouts for boosting power thru a power amp (just added).

Buying an AVR with preouts was the correct decision for me. I'm set up as a 5.2 becasue I biwired the front speakers using two speaker outs from the Onkyo. It will remain a 5.2 when the new amp is installed.

I see the 707s are deeply discounted now as Onkyo and others hurry to add 3D to their models. Hope this helped a little.

Dave

Ric5811

Jimbobwey wrote: »

When I get an amplifier, do I want to purchase a 2 channel or 7 channel...ultimately I want a 7.2 setup. I figure the floorstanding speakers are going to suck the most energy so a 2 channel would make sense but does that mess up the other 5 speakers?

You will want a 5 chan amp, unless you have the space to accommodate a 7.1 setup.

IMHO, 5.1 is as good or better than 7.1. The extrra 2 chans in 7.1 are artificially created .

Get a good used 5 chan amp and you will be fine.

Erik Tracy

Also keep in mind that the sensitivity of a speaker is measured at 1Meter.

You will loose db the further you sit away.

Free space loss is -6db for every doubling of the distance.

So from 1m to 2m to 4m (~12ft) away you would experience a -12db loss in spl (free space loss).

You may not experience the full loss because of room acoustics/reflections, etc, but even so there is some loss that needs to be refactored into your power calculations for desired spl at your listening spot and corresponding power.

Wasn't the 'benchmark' of loudness a Who concert at something like 110db? :eek:

I would think that the average spl would be considerably lower -but where power gets gobbled up is in transient peaks where there could be sonic 'bursts' x2 relative loudness and so require x10 the power.

I think that is where amp headroom is the saving grace against nasty dangerous clipping

Erik Tracy

So taking your example.

Let's say that at 12ft away, instead of a full -12db loss, you only loose 6db due to room acoutics.

If you want to be loud at 97db at your listening spot - you would need to be at 103db at 1meter (down 6db) and your power is at 16 watts - for average spl.

Now say a transient peak comes along in your listening at x2 loudness requiring x10 power. The amp would have to be able to deliver 160watts for that peak - else it will clip.

McLoki

Erik Tracy wrote: »

So taking your example.

Let's say that at 12ft away, instead of a full -12db loss, you only loose 6db due to room acoutics.

If you want to be loud at 97db at your listening spot - you would need to be at 103db at 1meter (down 6db) and your power is at 16 watts - for average spl.

Now say a transient peak comes along in your listening at x2 loudness requiring x10 power. The amp would have to be able to deliver 160watts for that peak - else it will clip.

You are probably pretty close (you would gain 6db since you have 2 speakers playing and lose 12 db due to distance, so about 6db down is probably pretty accurate.) Using the chart he provided for 1 meter...

91db 1 watt
94db 2watt
97db 4 watt
100db 8 watt
103db 16 watt
106db 32 watt
109db 64 watt
---- (Clipping starts to occur?)
112db 128 watts
115db 256 watts

If you want to play at 110db at the listening position, it would be the same as playing at 85db at 1meter (therefore you would need 256 watts). As you correctly stated - if you had a 10db peak in the noise level (doubling the volume) - you would need 2500 watts to continue playing without clipping.

I think of amps like this:

If you want better sound quality and maybe a little better headroom, just in case - an amp will give it to you. It will provide better sound quality through much better control of the speaker cones and maybe a little more headroom for peaks, but not much more real volume (unless it is a REALLY powerful amp).

If you really want to mainly play louder - you should be looking at a more efficient speaker, not a larger amplifier. Some Cerwin-Vega and Klipsh speakers are over 100db efficient. The same senario listed above would put you at 110 db with only 32 watts of power and your AVR would still choke at the required watts to handle the 10db peak (320 watts) but a large amp may get you there.

Here is a comparison of the volume you would get with your 91db efficient speakers compared to some 101db efficient speakers (once again with a 6db loss considering speaker distance and multiple speakers playing)
[php]
Watts 91 - 6db 101 - 6db
1 85 95
2 88 98
4 91 101
8 94 104
16 97 107
32 100 110
64 103 113
128 106 116
256 109 119
512 112 122
1024 115 125
[/php]

As you can see - if you really want volume, it is alot easier to get it with speaker efficiency than amplifier power.

weitrhino

You should very seriously consider a Sunfire Ultimate Receiver, either version I or II.

http://sunfire.com/manuals/913-108-00%20Rev%20A%20URII.pdf

http://sunfire.com/manuals/Ultimate%20Receiver%20Manual%20RevC.pdf

Jimbobwey

Wow guys, I seriously got back from work and I have all of this fabulous information brought to my attention. I've had another thread started talking about good amps I should be looking at (I gave three I was looking at buying) since I will probably be getting an amp before an AVR.

The thread link is http://www.polkaudio.com/forums/showthread.php?t=103595

Very rarely will I crank to volume to high db's, but I just want the reassurance that I can turn it up without blowing up the amp or speakers. I keep good care of my things and like to read up so nothing is done improperly.

woodguru

BlueFox wrote: »

I don't think you realize how loud 110db really is.

I don't want to be in the room, there's also a huge difference between decibels generated with clean massive power and small overtaxed with distortion, that distortion hurts the ears.

One thing I had to learn with super clean mondo equipment was that your ears don't hurt from distortion so it's easier to get into hearing damaging levels because it sounds so good. I was using 1400 watts each Belles monoblocks.

Good luck on the power quest, I'd go with a two channel amp first because you'll enjoy that more with music.

tonyb

110 db's is not good for the ears,regardless if it's clean or has distortion. If the OP wants to play that loud for extended periods,get pro gear and make sure hearing loss is covered in your policy.