Help understanding my recievers (and speakers) specs

[Liquidoodle]

I'm hoping someone could help me out with understanding my amps output specs.

It's a 5.1 DTS Kenwood KRF-V5050D which I believed back 5 years ago when I was young and impressionable output 100w per channel at 8 ohms.

I've looked at the manual again today and it's not and was wondering if someone could help me understand what it would output with my speakers at 8 ohms.

I'm also having trouble understanding all those numbers and terms and theres only so much searching wikipedia, google and here is helping with lol!

The manual states "Effective power output during STEREO operation" as being
DIN/IEC (DIN 1kHz, 0.7% T.H.D., at 6 ohms) 110w + 110w

Then in 5.1 "Effective power output during SURROUND operation" as being
FRONT (1kHz, 0.7% T.H.D., at 6 ohms one channel driven) 100w + 100w
CENTER (1kHz, 0.7% T.H.D., at 6 ohms one channel driven) 100w
SURROUND (1kHz, 0.7% T.H.D., at 6 ohms one channel driven) 100w + 100w

My speakers for the fronts are 100 watt 8 ohms, center is 120 watt 8 ohms and rears are 90 watt 4-8 ohms

So any ideas of the output at 8 ohms instead of 6? Is there some formula you can use to work it out?

Any ideas what the DIN/IEC, DIN 1kHz and THD stuff is all about?

Also the one channel driven bit, does that mean (1kHz, 0.7% T.H.D., at 6 ohms) each speaker?

.... baffled much!!!

Also is there anyway of getting say wattage, resistance, sensitivity etc. and working out the total volume of a system or is it a case of get some equipment to measuer it.

Thanks In Advance

 

[MDS]

DIN is one of many rating standards. Others are FTC (USA) and EIAJ (Japan).

The DIN standard rates one channel at a time using a single frequency of 1 kHz. 1 kHz is right in the middle of the frequency range so DIN ratings show higher numbers and don't give a very good indication of power.

FTC ratings use two channels and the entire frequency range from 20 Hz - 20 kHz. I think EIAJ is similar to DIN.

THD is Total Harmonic Distortion. Anything under 1% is mostly inaudible but better receivers have THD figures around .07% (an order of magnitude better than the Kenwood specs).

The 8 ohm rating will be lower than a 6 ohm rating but since they give no full bandwidth specs it's anybody's guess what it will output when 2 or more channels are driven at the same time. (6/8)*100 = 75 watts is a close guess for one channel driven at 1 kHz but the full bandwidth rating will be lower still.

 

[Liquidoodle]

Cheers

Cheers MDS that helps a lot!!!!

It's been a while since I've looked into this kind of thing & I do believe last time I was about 16 and had the idea of "More Watts Equals More Volume" as unfortunately the myth goes!

I've also just realised that I have an underpowered amplifier for all of my speakers which is why it clips a bit or switches off at high volume..... wonderful!!!!

Nevermind, gives me even more incentive to go for a new 7.1 in the future

 

[Davemcc]

So any ideas of the output at 8 ohms instead of 6? Is there some formula you can use to work it out?

When the ohms are cut in half, the power rating should nearly double (in a perfect world with no losses, it would double). Moving from six to eight ohms would reduce the power rating by 25-30%.

The manual states "Effective power output during STEREO operation" as being
DIN/IEC (DIN 1kHz, 0.7% T.H.D., at 6 ohms) 110w + 110w

Under the bracketed test conditions, the amp should put out 110w on each of the 2 main channels. If you measured at 8 ohms, it would likely be about 80w. If you were then to apply a more rigorous testing standard, the watt rating will drop. For instance, instead of testing at a single frequency (1KHz), if you test at the full audible spectrum (20Hz-20kHz) the rating will drop. If you test at 0.03% T.H.D., the rating would drop again. These standards are chosen because it is easier to achieve a higher wattage rating (advertising rating) because you're not placing great limitations through testing standards.

Then in 5.1 "Effective power output during SURROUND operation" as being
FRONT (1kHz, 0.7% T.H.D., at 6 ohms one channel driven) 100w + 100w
CENTER (1kHz, 0.7% T.H.D., at 6 ohms one channel driven) 100w
SURROUND (1kHz, 0.7% T.H.D., at 6 ohms one channel driven) 100w + 100w

When it says "one channel driven" they mean just that. It will only achieve that rating if only one speaker is active (and likely burn out a fraction of a second later). The inference is that the power supply is inadequate to drive all channels to those levels simultaneously and if you were to test all channels simultaneously, the power rating would again be significantly reduced when it reached the allowed testing standards.

My speakers for the fronts are 100 watt 8 ohms, center is 120 watt 8 ohms and rears are 90 watt 4-8 ohms

The wattage rating on speakers is virtually meaningless.

Any ideas what the DIN/IEC, DIN 1kHz and THD stuff is all about?

I freely admit that I don't know what DIN/IEC stands for. But the 1kHz is telling you that all ratings are done at a single frequency instead of testing throughout the entire audible range. THD is total harmonic distortion and the lower number the better. Something like 0.03% is a much higher standard to achieve than 0.7%.

Also the one channel driven bit, does that mean (1kHz, 0.7% T.H.D., at 6 ohms) each speaker?

One at a time.

Also is there anyway of getting say wattage, resistance, sensitivity etc. and working out the total volume of a system or is it a case of get some equipment to measuer it.

Thanks In Advance

I'm sure it could be measured under a more exacting standard, but I'm not sure you'd like the rating as measured 20Hz-20kHz, 0.003% THD, 8 ohms, all channels driven.

 

[Liquidoodle]

Wow man that's a reply!!! wheres the head exploding smilie when you need it

I think I get a lot of it, though I'm not sure about the whole speaker rating being meaningless, don't you match them to your amp that way? 100w output on amp to 100w speakers etc.? If not how on earth do you match them?

I think my main question now is..... am I damaging my speakers in any way? I do tend to crank the volume up on the odd occassion.

I read that an underpowered amp damages speakers more than an overpowered one you see.

Cheers Davemcc btw, awesome reply! Your a star!

 

[avaserfi]

First off you don't need to match your amps wattage to your speakers just make sure you have an amp that can deal with the resistance (ohms).

Turning up your system is fine, but if you hear clipping turn it down that can easily blow your speakers and just remember that volume level and avoid it until you can upgrade your receiver.

 

[Liquidoodle]

Ok kewl getcha!! So speaker wattage really is useless!!!

Cheers

 

[PENG]

Ok kewl getcha!! So speaker wattage really is useless!!!

Cheers

One of the problems with loudspeaker wattage spec is that you cannot go by the wattage only. You have to know also the impedance characteristics, by that I mean not only the ohmic values that varies with the frequency of the signals, but also the phase angle (also frequency dependent) between the voltage and current phasors, among other things. For example, your 100WPC amp may "match" with a 100W rated Paradigm, but it may not be as good a match with a 100W Polk, even if they are both rated for 8 ohms. You could, in many cases compare the power ratings of speakers within a product line of the same manufacturer. For example, your amp will have less chance of damaging the woofer/mid range of a Paradigm Studio 100 than it would do to a Studio 20 at the point of clipping. Same deal for a Polk RTi10 and a RTi8.

Bottom line, the wattage spec of a speaker is not completely useless, but you can take it to the bank neither. I hope I succeeded in confusing you.

 

[Davemcc]

Cheers Davemcc btw, awesome reply! Your a star!

You might want to get third party confirmation of anything I say. The little bit of knowledge I have to share could be dangerous.

Having duly warned you, you might notice that some speaker manufacturers give a recommended power rating of maybe 5w-100w or 50z-250w. This just puts you in a range of what the manufacturer thinks is safe. But a 50w amp will drive most speakers just fine when kept within its own safe range, but destroy most speakers when driven to distortion. The same is true of the 200w amp, but there is a much larger range of power before it's driven to distortion. Mind you, it's unlikely that you could pump 200w into a 5w speaker without damage, but then again, that's pretty far out of the suggested range that you can expect damage.

When choosing an amp to drive a particular set of 100w speakers, you can safely choose either a 50w amp or a 200w amp as long as you use common sense in their operation. It's in this sense that I say the speaker's rating is virtually useless. It's really the amps rating and how you use it that are important.

 

[PENG]

One of the problems with loudspeaker wattage spec is that you cannot go by the wattage only. You have to know also the impedance characteristics, by that I mean not only the ohmic values that varies with the frequency of the signals, but also the phase angle (also frequency dependent) between the voltage and current phasors, among other things. For example, your 100WPC amp may "match" with a 100W rated Paradigm, but it may not be as good a match with a 100W Polk, even if they are both rated for 8 ohms. You could, in many cases compare the power ratings of speakers within a product line of the same manufacturer. For example, your amp will have less chance of damaging the woofer/mid range of a Paradigm Studio 100 than it would do to a Studio 20 at the point of clipping. Same deal for a Polk RTi10 and a RTi8.

Bottom line, the wattage spec of a speaker is not completely useless, but you can take it to the bank neither. I hope I succeeded in confusing you.

Edit: I meant to say ...."you cannot....." in my second last sentence.

 

[Liquidoodle]

Hehe, Dave i've been looking around quite a bit at info and your post seemed to summarise everything quite nicely

And Peng.... I'm thoroughly confused!!!!..... well not really It's all making sense now, explains why my speakers do the trick well and sound pretty darn loud yet they won't go to the loudest setting on the amp as well the amp shuts it'self down because it canny take the power!!!!

Cheers Guys, am thinking of making a plain english noobie guide.... Why wattage matters and doesn't! LOL