having a hard time with the Hz-kHz conversion...

[wynterfire]

ok, before I start, I'll say that math was never a strong subject for me. So please talk to me like I'm a dumbass.

and I know that 1 hertz = 0.001 kilohertz. Now...

I just bought a pair of Pioneer S-HF21-LR bookshelf speakers and the specs say that the frequency response is 55~20 kHz.

The current speakers I have from my Kenwood HTIB have 100 Hz~20,000 Hz.

Now, if I'm doing this right, to get the specs for my current speakers (the kenwoods) in kHz I'd have to multiply each number by .001. So 20,000 Hz would be 20 kHz. BUT, if I multiply 100 by .001, I get 0.1 ...which to me desn't make much sense specs wise because my new Pioneers are written as 55~20 kHz. So the Kenwoods would be written as .1~20 Khz if it were in kHz.
I know I've also seen times when I see the specs written as 100Hz~20kHz (which makes sense), so part of me thinks the Kenwood spec sheet has a typo. But there are specs for all the speakers in my HTIB written on the same page in different charts (so if it is a typo, it's repeated a few times).

Hope you are following so far. And I hope I'm making sense.

Now looking on Axioms site, the surrounds I want (QS8's) are listed as:
Freq Resp +/-3db (Hz): 95 - 22 kHz
Freq Resp +3dB- 9dB (Hz): 65 - 22 kHz


So if I'm correct, the feq. range on the Axioms are better than the Pioneers 55~20 Khz range, but what about the Kenwoods 100 Hz~ 20,000 Hz? I can't imagine that cheap HTIB speaker would have the same frequency range as high quality speakers, but the Pioneers which are about $30 retail each would be less than the Kenwoods (even the Pioneers that are around $100 each have seemingly smaller freq. range than the Kenwoods: see next paragraph).

Another thing that confuses me GREATLY is that I also see on the spec sheet for the Pioneer speakers that list 4 different models (each better than the first) that the freq. range SHRINKS as you go down the list. i.e. the cheapest speaker's range is 55~20 kHz, while the best is 40~20 kHz. I would think that the better (more expensive) the speaker is, the wider the frequency range would be (at least that's what I see on Axiom's site and other places). Someone help me with THAT.

Basically I'd like to know how EXACTLY to convert Hz to kHz and which speakers have the best range. And what's the deal with the shrinking freq. range on the Pioneer spec sheet.

Please help.... my brain is gonna explode

[PunkMunkey]

OK...I read your post and will give this a go...

1000 hz = 1 khz or like you said 1hz = .001 khz

Frequency specs are often listed in one of 2 ways:

20 hz-20 khz or 20 hz-20,000 hz (the two ranges are equal).

The lower you go on the scale, the lower your speakers will play, that is, it will handle lower bass frequencies.

The freq. range on the Axioms is: 95 hz - 22 kHz
The freq. range on the Pioneers is: 55 hz - 20 Khz

This means that according to furnished the specs, the Pioneers will play lower bass than the Axioms but the Axioms will play higher highs than the Pioneers...but again, that's only going by thier furnished specs and it does not take into account sound quality, only frequency range.

Generally, you'd want to look for a speaker with the broadest range meaning that the lower limit would be closer to 0 and the upper limit would be as high as you could get it.

20 hz - 20,000 hz (or 20 khz) is considered "full range" but it's not uncommon to see subwoofers posting lower limit specs in the teens (IE 15 hz) and some high end manufacturers claiming that ther speakers cover up to 30,000 hz (30 khz) on the upper end.

The easiest thing to do might be to try to think of everything in terms of just hz. That way you can just look for the broadest range when considering specs. I'm simplifying that a bit because I'm not taking into account the -3dB points but that might be a post for another time...

Hope that helped.

[Taxi]

Originally Posted by PunkMunkey

I'm simplifying that a bit because I'm not taking into account the -3dB points but that might be a post for another time...

But it's that -3dB that is probably the most critical part.

First of all, I think it is pretty common for frequency range to be listed as 55 - 20kHz, with it being assumed that 55 = 55 Hz, not 55kHz.

Second, there are two issues to consider when talking about frequency response/range, the range itself, and the LIMITS of that range, the +- 3dB number.

If you saw specs that said your speakers could do 20 - 20kHz (+- 18dB) then that isn't so great compared to some that spec'd out at 20 - 20k (+- 3dB). What that number is representing is the amount of volume difference compared to a flat signal over the specified range. This value usually represents a dropoff, or frequencies where the speaker just can't reproduce the given frequency.

The number for the Axiom speakers that you listed show that there's a 6dB dropoff between 95Hz and 65Hz. This is probably not a bad thing, depending on how your home theater is setup. (In other words, it's probably not likely that you're going to need your surrounds to handle frequencies that low, your subwoofer can handle them for you.)


I hope I didn't babble too much...

[tomdkat]

You guys are making great sense, thus far. I concur with Taxi that the frequency is assumed to be a measurement of Hz unless indicated as being KHz.

Peace...

[Pirate]

I have a hard time with this stuff. I set my rec at 100khz and then just used my ears to calibrate. Lousy machines and their lousy math!

-PH

[PunkMunkey]

Originally Posted by Taxi

But it's that -3dB that is probably the most critical part.

Yeah, the amplitude range is very important when trying to interpret what a speaker might sound like...it's generally accepted that any amplitude change between 0 and +3 db or 0 and -3 db would be fairly imperceptible (0 being flat response)...once you start to get beyond 3 dB from 0 (flat) the changes in amplitude are easier to notice...

With respect to this, speakers with smaller gaps in amplitude tend have what's considered a flatter response, meaning the sound you get out of them will more closely mirror the input signal...so, a speaker with a response of 20 hz - 20,000 hz (+/-3 dB) would give a flatter response curve (generally) that a speaker with a response of 15 hz - 30,000 hz (+/-12 dB)...basically the +/- range denotes a tolerance or "room for error" factor in actual response. The less room for error, the better a speaker has the ability to sound (theoretically...as with everything there are probably exceptions).

[tomdkat]

Thanks for theat explanation, PunkMonkey.

Now, in the case of the QS8's being discussed here, the 65-22KHz @ +3b-9db numbers mean the speakers won't have a flat response with audio signals in that frequency range?

Also, how does sensitivity factor in? I mention this since the specs for my speakers mention sensitivity but don't give amplitude ranges for the frequency response (See the attached image).

Peace...

[Taxi]

Sensitivity is a measure of how much volume a speaker outputs for a given power input. It doesn't really indicate how good/bad a speaker will sound, only how loud it will sound. (Sensitivity is sometimes called "efficiency".)

Usually sensitivity is measured by inputting 1 watt of power into the speaker, and measuring the volume at 1 meter in an anechoic chamber. The speaker spec you listed Tom says the power input was 2.83V. I suck at electronics, so I don't know how this compares to watts. Regardless, 92dB in an anechoic chamber is a pretty good number. That speaker should have no trouble producing sufficient volume in small to medium sized rooms.

Typically speakers with horn drivers are more effecient (think Klipsh) but some people don't like the sound of horn drivers compared to dome/cone drivers.

[PunkMunkey]

Just to elaborate a bit on what Taxi said...

2.83 Volts corresponds to the voltage across a standard 8ohm speaker driven at 1 Watt. So for all intents and purposes, when dealing with 8ohm speakers 1W = 2.83V. Now, as the speaker's impedance changes so does the voltage...but again, delving into that may just be confuse the issue.

One thing to take into account with respect to sensitivty is the power needed to reach adequate volume. It is generally accepted that every for 3 dB increase in amplitude one requires a doubling of power (in Watts).

To illustrate, Tom's speakers start out with a baseline 92 dB sensitivity @ 1W...in order for him to reach reference level (105 dB peaks at the listening position according to Dolby Labs)...therefore:

@ 1W = 92dB
@ 2W = 95 dB
@ 4W = 98 dB
@ 8W = 101 dB
@ 16W = 104 dB
@ 32W = 107 dB
@ 64W = 110 dB

Tom would need between 16 and 32 Watts to generate the SPL of reference level with program material (not test tones).

As far as the QS8's and their response curve, it's true that they will not have what's considered a flat response curve, however, depending on what the curve actually looks like, they may still yield very good results.

[wynterfire]

Originally Posted by Taxi

If you saw specs that said your speakers could do 20 - 20kHz (+- 18dB) then that isn't so great compared to some that spec'd out at 20 - 20k (+- 3dB). What that number is representing is the amount of volume difference compared to a flat signal over the specified range. This value usually represents a dropoff, or frequencies where the speaker just can't reproduce the given frequency.

Thanks for explaioning this for me. As this was one of those things that baffled me as well.

Originally Posted by Taxi

The number for the Axiom speakers that you listed show that there's a 6dB dropoff between 95Hz and 65Hz.

Now how did you come up with 6dB?
Where in the specs does it help you determine the dropoff point and at, and what the dB rate is. I pretty mych deduced that if there are 2 different freq. ranges (i.e. Freq Resp +/-3db (Hz): 95 - 22 kHz
Freq Resp +3dB- 9dB (Hz): 65 - 22 kHz ) that the first numbers in the 2 would give you the range at which the dropoff occurs. Am I right?

It's interesting to hear about this dropoff as well because after hooking up the new speakers, I recalibrated the whole soundfield to compensate. When I did a high to low frequency sweep, I noticed said dropoff at 2 points. The first was around 80 Hz, and the second roughly around 60 Hz (when the higher LFE register turned deeper. And I noticed that when tooling with my sub's crossover settings (with my receiver's crossover settings on at 80 Hz), the dropoff occured at different places.

[wynterfire]

Originally Posted by PunkMunkey

To illustrate, Tom's speakers start out with a baseline 92 dB sensitivity @ 1W...in order for him to reach reference level (105 dB peaks at the listening position according to Dolby Labs)...therefore:

@ 1W = 92dB
@ 2W = 95 dB
@ 4W = 98 dB
@ 8W = 101 dB
@ 16W = 104 dB
@ 32W = 107 dB
@ 64W = 110 dB

Tom would need between 16 and 32 Watts to generate the SPL of reference level with program material (not test tones).

Not DIRECTLY related to this, but I'm also wondering why receivers work in NEGATIVE dB levels. For instance, my receiver, at a comfortable but nicely loud setting will show as -24 dB on the display (and when I do pink noise tests it goes to 0 dB). Now if a normal conversation registers as POSITIVE 60 dB in real life to the human ear, why in the hell do the receivers use negative settings?

Originally Posted by PunkMunkey

As far as the QS8's and their response curve, it's true that they will not have what's considered a flat response curve, however, depending on what the curve actually looks like, they may still yield very good results.

I find this interesting as well. I would think that Axiom, in it's ongoing research would add a little "color" to their speakers to spice up the HT experience. I subscribe to their e-mail newsletter and they have some VERY intereesting articles about their research and sound in general. I recommend anyone interested subscribe.

[wynterfire]

Originally Posted by piratehunter

I have a hard time with this stuff. I set my rec at 100khz and then just used my ears to calibrate. Lousy machines and their lousy math!

-PH

Tell me about it. I just about blew a few blood vessels trying to recalibrate the MCACC manually with the new speakers.

[Taxi]

Originally Posted by wynterfire

Thanks for explaioning this for me. As this was one of those things that baffled me as well.

You're welcome. That's what we're here for.

Now how did you come up with 6dB?

From your previous post:

Originally Posted by Post #1

Freq Resp +/-3db (Hz): 95 - 22 kHz
Freq Resp +3dB- 9dB (Hz): 65 - 22 kHz

What they're saying is that between 95Hz and 22kHz, the speakers show flat response, plus or minus 3dB. But between 65Hz and 22 kHz, they show plus 3dB to minus 9dB. I made the assumption that the greatest variance in amplitude between 95 and 22kHz was at 95Hz, because I've seen lots of graphs of this data, and they almost always drop off at the low side (and at the high side). In other words, it's the extrememes that speakers have a hard time reproducing.

Anyway, since we have a maximum 3dB drop at 95Hz, but a maximum 9dB drop down to 65Hz, I subtracted 3 from 9 to get a 6dB drop between 65Hz and 95Hz.

[tomdkat]

Originally Posted by wynterfire

Not DIRECTLY related to this, but I'm also wondering why receivers work in NEGATIVE dB levels. For instance, my receiver, at a comfortable but nicely loud setting will show as -24 dB on the display (and when I do pink noise tests it goes to 0 dB). Now if a normal conversation registers as POSITIVE 60 dB in real life to the human ear, why in the hell do the receivers use negative settings?

I think that's in relation to "reference level". So, at -24db, your volume is 24dbs lower than reference level. So if 105db is SPL reference level (according to Dolby labs), your volume level is 105-24=81db.

My volume level is -20db when watching DVDs.

Peace...

[tomdkat]

Originally Posted by PunkMunkey

To illustrate, Tom's speakers start out with a baseline 92 dB sensitivity @ 1W...in order for him to reach reference level (105 dB peaks at the listening position according to Dolby Labs)...therefore:

@ 1W = 92dB
@ 2W = 95 dB
@ 4W = 98 dB
@ 8W = 101 dB
@ 16W = 104 dB
@ 32W = 107 dB
@ 64W = 110 dB

Tom would need between 16 and 32 Watts to generate the SPL of reference level with program material (not test tones).

Ok. My receiver is rated at 90Wx5 and a couple of years ago someone claimed in reality my receiver probably started "clipping" at 76W or so.

Given those numbers, my receiver should have no problem providing sufficient power to drive my speakers (the front mains we've been discussing here) at SPL reference levels, correct?

Peace...

[Taxi]

Yeah, Tom, I think you're good to go.

[PunkMunkey]

Originally Posted by wynterfire

Not DIRECTLY related to this, but I'm also wondering why receivers work in NEGATIVE dB levels. For instance, my receiver, at a comfortable but nicely loud setting will show as -24 dB on the display (and when I do pink noise tests it goes to 0 dB). Now if a normal conversation registers as POSITIVE 60 dB in real life to the human ear, why in the hell do the receivers use negative settings?

Originally Posted by tomdkat

I think that's in relation to "reference level". So, at -24db, your volume is 24dbs lower than reference level. So if 105db is SPL reference level (according to Dolby labs), your volume level is 105-24=81db.

It might also be in reference to power output at clipping...where 0 dB is the point where maximum "clean" power is delivered...

Originally Posted by tomdkat

Ok. My receiver is rated at 90Wx5 and a couple of years ago someone claimed in reality my receiver probably started "clipping" at 76W or so.

Given those numbers, my receiver should have no problem providing sufficient power to drive my speakers (the front mains we've been discussing here) at SPL reference levels, correct?

Given those numbers, your receiver is more than adequate to produce reference levels with a bit of headroom to spare.

[Pirate]

So if the Axioms have a drop off of 95 and your receiver pushes 110w per channel...that means what? I think I'm missing something.

-PH

[tomdkat]

Originally Posted by piratehunter

So if the Axioms have a drop off of 95 and your receiver pushes 110w per channel...that means what? I think I'm missing something.

Yep, about 6db.

Peace...

[Pirate]

where did my 6db go?!

-PH

[PunkMunkey]

OK...I'll give this explanation a shot and hopefully it will make sense.

I'll use the Axiom specs in the above post since those are the ones at hand.

Given:
Freq Resp +/-3db (Hz): 95 - 22,000
Freq Resp +3dB/-9dB (Hz): 65 - 22,000

We can deduce (as Taxi did) that there is a -6 dB roll off between 95 hz and 65 hz.

Let's say that the Axioms have an average sensitivity of 90 dB @ 1W, meaning that at 1W they'll produce 90 dB over most of their frequency range. We're going to power them with 110W (via piratehunter's reciever)...so knowing that for every 3 dB increase we need to double power input we can expect that with 110W we'll get an output of somewhere in the 109 dB range (estimated because of the logarithmic nature of SPL) for the majority of the frequency band.

However, because the response dips 6 dB from 95 hz to 65 hz we can expect that if the volume at 95 hz is in fact 109 dB, then the volume at 65 hz will be 103 dB...6 dB less, because of the natural roll off characteristics of the speaker.

[Iguana Man]

Originally Posted by tomdkat

Ok. My receiver is rated at 90Wx5 and a couple of years ago someone claimed in reality my receiver probably started "clipping" at 76W or so.

Peace...

This is sounding familiar...I think I remember posting something like this a couple years ago, but it was the actual 'output' when driving all 5 speakers that was closer to 76wpc, not Pioneers stated 90wpc. No mention of clipping if it was I you refer to.

I've yet to clip my (our) receiver, so I too think you (we) are fine.

[tomdkat]

Originally Posted by Iguana Man

This is sounding familiar...I think I remember posting something like this a couple years ago, but it was the actual 'output' when driving all 5 speakers that was closer to 76wpc, not Pioneers stated 90wpc. No mention of clipping if it was I you refer to.

Yeah, that sounds like what I was talking about but it wasn't you who posted that info. It was that guy who ripped off a number of us through bunk DVD trades, way back when. I forget his handle.

I'll see if I can find his comment and post a link. "clipping" was the term he used but your description above sounds like what he was describing.

Peace...

[Taxi]

Originally Posted by tomdkat

I'll see if I can find his comment and post a link.

Is this your card?