Calling All Audiophilic Types

[Tomorrow]

AverageJoe and I collaborated on a couple of questions for you cognicenti out there. All information is gratefully accepted. (Any resemblance to an intelligent question is purely accidental, btw. We were gonna hire a 'thinking' person, but there are none available in rural Oregon. ) So, without further ado.....

1. What exactly IS LFE (low freq. effects)? When my DVD plays in 6-channel surround, all presets on the dvd are in play. ALL LFE goes to the sub. What exactly IS that? Is is merely some prearranged frequency level(s)? My receiver has settings for small and large mains. When small is selected, I can manually set the Xover at 100, 150, or 200hz. So what goes to the sub when I select large mains? No help from the manual, btw. But the sub is connected via the LFE out from the receiver, Xover out on the sub. All LFE goes to the sub. What is all?

2. When you speak of listening to your system (HT, e.g.) and you say it was set to "reference level", what does that mean? The Avia disk says that setting each speaker to "reference level" is done at 85db. When you listen to your HT at "reference level" is it with the entire system at that 85db level or each speaker pouring out an average (I suppose) of 85db at your favorite listening spot? On the other hand, most speaker specs are rated at around 90db +/- a few, at 1 meter (should one assume anechoically?). Does that have some relevance to "reference level"? (I told you these were likely dumb questions.)

3. Some of the universal remotes we've seen look pretty nice. Are there any out there that have the Audioholics Seal of Approval for The Sisters (Brothers in this case) of the Poor? Any recommendations?

4. Finally, what does it mean when folks like Axiom say their speakers perform down to 35hz +3/-8db?!! Is that an attempt at deception or is it some obscure but valid measurement?

Thanks for your increasingly patient tolerance of us electronically challenged folks.

 

[Tomorrow]

Addendum to dopey questions

I forgot one.....most receivers we've seen claim a nominal frequency range of 20hz-20khz. Does that mean they don't go below 20hz? What does that mean for subsonic bass delivery like the 18hz SVS's? Does it then NOT get a signal at that frequency?

 

[mtrycrafts]

Boy, you sure have a plateful

1. What exactly IS LFE (low freq. effects)? When my DVD plays in 6-channel surround, all presets on the dvd are in play. ALL LFE goes to the sub. What exactly IS that? Is is merely some prearranged frequency level(s)? My receiver has settings for small and large mains. When small is selected, I can manually set the Xover at 100, 150, or 200hz. So what goes to the sub when I select large mains? No help from the manual, btw. But the sub is connected via the LFE out from the receiver, Xover out on the sub. All LFE goes to the sub. What is all?

LFE as you indicated, low frequency effect is where the mixers usually place the low level special effect sound, cannon blasts, explosions, etc.

If you play the Telarc 1812 overture, the cannon blasts will come from there if set up correctly
Instrument lows usually come from the other channels if you have them set to large.

2. When you speak of listening to your system (HT, e.g.) and you say it was set to "reference level", what does that mean? The Avia disk says that setting each speaker to "reference level" is done at 85db. When you listen to your HT at "reference level" is it with the entire system at that 85db level or each speaker pouring out an average (I suppose) of 85db at your favorite listening spot? On the other hand, most speaker specs are rated at around 90db +/- a few, at 1 meter (should one assume anechoically?). Does that have some relevance to "reference level"? (I told you these were likely dumb questions.)


Well, it is like this. When you use a test disk, Avia has a signal level, referenced to full scale level that a DVD will accept or set by standards. Another test disc may have it at a lower level for sure as they want you to level match at 75dB spl.

However, these levels are not important. What matters is where the master volume control is set at, not the individual channel trim pots, when you level match the speakers. Now, if on playback of a movie you set your master volume control to this position, you are at reference level. If the DVD has a full scale audio signal, your speakers will reach 105 dB spl in that channel. This is reference level for max loudness at the seats, minus the sub. that is 115 dB spl max. This is so because your hearing volume in the low band is poor, not as sensitive to it as in mid band.



4. Finally, what does it mean when folks like Axiom say their speakers perform down to 35hz +3/-8db?!! Is that an attempt at deception or is it some obscure but valid measurement?

Well, not deception but not very useful. This is the response in an anechoic chamber to frequency response with a fixed input signal of all frequencies. But, this will not tell you what that response level is as it may not be able to reproduce 35Hz at a level that is usefully audible. Hence, it is worthless.

If you are interested in speaker response, check out reviews by Sound & Vision, although they don't do many. if Tom Nousaine's name on the charts, or David Ranada, you can bank on it.
Stereopile does decent measurmetns on speakers too. That is harder to fake as another lab can confirm it or refute it. Certainly different from a biased, subjective evaluation of that speaker
Thanks for your increasingly patient tolerance of us electronically challenged folks.

 

[mtrycrafts]

I forgot one.....most receivers we've seen claim a nominal frequency range of 20hz-20khz. Does that mean they don't go below 20hz? What does that mean for subsonic bass delivery like the 18hz SVS's? Does it then NOT get a signal at that frequency?

I believe that th eLFE may have a lower frequency output as it doesn't depend on the receiver amps.
Besides, the frequency response of the internal amps do go below and above the 20Hz-20Khz but it may not be as flat as from 20-20k. It isn't that it will not reproduce a 19Hz or 15 Hz, signal, just that it may be a bit below the others. Not to worry. Your SVS will do well

 

[MDS]

Adding more to what mtrycrafts has already said:

1. What exactly IS LFE (low freq. effects)? When my DVD plays in 6-channel surround, all presets on the dvd are in play. ALL LFE goes to the sub. What exactly IS that? Is is merely some prearranged frequency level(s)? My receiver has settings for small and large mains. When small is selected, I can manually set the Xover at 100, 150, or 200hz. So what goes to the sub when I select large mains? No help from the manual, btw. But the sub is connected via the LFE out from the receiver, Xover out on the sub. All LFE goes to the sub. What is all?

As noted, LFE is Low Frequency Effects. It is a channel that is dedicated solely to very low frequencies. It is the ".1" in 5.1, 6.1, 7.1 etc. - so named because it only carries roughly 1/10 of the audible range of frequencies (20 Hz - 120 Hz). The .1 channel is for the really low bass - like the dinosaur feet stomping in Jurassic Park.

If your setting is 'All LFE to the sub' then only the sub will get LFE - not the mains. If you were to set the subwoofer=no (or off) then the mains will get the LFE if they are set to Large.

2. When you speak of listening to your system (HT, e.g.) and you say it was set to "reference level", what does that mean? The Avia disk says that setting each speaker to "reference level" is done at 85db. When you listen to your HT at "reference level" is it with the entire system at that 85db level or each speaker pouring out an average (I suppose) of 85db at your favorite listening spot? On the other hand, most speaker specs are rated at around 90db +/- a few, at 1 meter (should one assume anechoically?). Does that have some relevance to "reference level"? (I told you these were likely dumb questions.)

The technical definition of Dolby Reference Level is 105 dB peaks at the listening position, as mtrycrafts said. This is arrived at by sending a signal that is -20 dB below 'full scale digital' (0dB). You calibrate so that the SPL meter reads 85 dB when playing that -20 dB signal. 85+20 = 105 dB peak (+10 more for the LFE).

If you were to calibrate so that reference level is achieved at 0 on the volume knob, then if you are listening with the volume knob at -10, you are listening at 10 dB below 'reference'.

The speaker 'sensitivity' that you refer to is entirely different. It is a measure of how loud the speaker will play. 91 dB/1W/1M means that when fed 1 Watt of power, the speaker will produce 91 dB SPl when measured 1 Meter from the speaker. Yes, it is measured anechoically. A typical room adds about +3 dB to that number. As in most things related to physics, sound pressure follows the inverse square law - every doubling of distance halves the sound pressure level. So that same 91 dB sensitive speaker that produces 91 dB 1 meter from the speaker, will produce roughly 85 dB 2 meters from the speaker. Higher sensitivity means that it takes less power to drive to high levels, but is not indicative of sound quality.

3. Some of the universal remotes we've seen look pretty nice. Are there any out there that have the Audioholics Seal of Approval for The Sisters (Brothers in this case) of the Poor? Any recommendations?

Home Theater Master, Harmony, Pronto are the big guns in universal remotes. They are all good and everyone has their preference. Mine is HTM. Used to have an MX-500 and now have an MX-350. They are truly 'universal' - mine controls every single function of every single device I own.

4. Finally, what does it mean when folks like Axiom say their speakers perform down to 35hz +3/-8db?!! Is that an attempt at deception or is it some obscure but valid measurement?

This is the stated frequency response of the speaker as measured in an anechoic chamber ("no echos"). It tells you over what frequency range the speaker can reproduce sound and by how much the output varies from the input. Usually they state it something like: 35 Hz - 20 kHz +/- 3 dB, which would mean that it can reproduce frequencies from 35 Hz - 20 kHz and the output signal's level will vary by no more than +/- 3 dB from the level of the input signal. Specs are nice but there are alot of factors that determine how it will actually sound in your room, so just use them as a guideline. Note that when people talk about the 'F3' point of their speakers, that is what they are talking about - the lowest stated frequency where the level will be down by only 3 dB (in your example - 35 Hz).

 

[Tomorrow]

These are GREAT responses, guys. Very clear and instructive. Many thanks. Please keep 'em coming. It is a fine primer for us dummies.

One point of clarification...the comment I made about the Axiom speaker being measured at 35hz, +3/-8db...was to highlight the -8db part of it. I've seen the +/-3 everywhere, almost as a convention to be nominally used. But this -8db part sounds like turkey baloney to me.

 

[mtrycrafts]

It is the ".1" in 5.1, 6.1, 7.1 etc. - so named because it only carries roughly 1/10 of the audible range of frequencies (20 Hz - 120 Hz). ).

I am pretty sure that the high end of the LFE is only 80Hz. I am sure that 80Hz is the top for a THX mastered sound track.
While some receiver's crossover may reach up to 120, or higher, not sure if all DVDs would have content between 80 and 120 in the LFE. The problem becomes localization of the sub.

 

[AverageJoe]

One of my discussions with RJ regarding LFE involved my subwoofer connections - It has 3 RCA inputs: L, R, and LFE. I currently have the subwoofer output of the receiver connected to L and have set up the system with the Avia disk and an SPL with crossover set at 100Hz.

What would I gain/Lose if I switch to the LFE input? Would I need to change the crossover to 80Hz?.. or set the speakers to "large" and let them pick up the low freq's. Is this input only for receivers that have an LFE output?

Still learning every day.

 

[MDS]

I am pretty sure that the high end of the LFE is only 80Hz. I am sure that 80Hz is the top for a THX mastered sound track.
While some receiver's crossover may reach up to 120, or higher, not sure if all DVDs would have content between 80 and 120 in the LFE. The problem becomes localization of the sub.

You know I almost added a sentence that said 'Although the LFE channel can go as high as 120 Hz, rare is the soundtrack that includes frequencies greater than 80 Hz in the LFE channel'. Guess I should have included that.

It is allowed to be as high as 120 Hz, but you are right that it rarely, if ever, is that high. I'm betting the reason that mastering engineers don't put much above 80 hz in the LFE is due to the THX recommended xover of 80 Hz.

 

[MDS]

What would I gain/Lose if I switch to the LFE input? Would I need to change the crossover to 80Hz?.. or set the speakers to "large" and let them pick up the low freq's. Is this input only for receivers that have an LFE output?

Still learning every day.

JBL sub by any chance? JBL subs have an input labeled 'LFE' as well as the normal L and R line level inputs. The only difference is that if you use the input labeled LFE the sub's internal xover is automatically disabled which is what you want if you are using the receiver's bass management. If you use the L input, the sub's internal xover will still be active and you should set it as high as it will go so that you don't get cascading xovers (the receiver and sub both acting on the signal).

 

[AverageJoe]

JBL sub by any chance? JBL subs have an input labeled 'LFE' as well as the normal L and R line level inputs. The only difference is that if you use the input labeled LFE the sub's internal xover is automatically disabled which is what you want if you are using the receiver's bass management.

Thanks for that info. Sorry to beat this to death, but -

Is this the case with any similarly labeled subwoofer (Mine is a Pinnacle Digital Sub 600)? My receiver does not have a selectable crossover frequency for the mains and surrounds - just a Small and Large choice. The subwoofer crossover can be set between 80 and 120Hz. Does this also control what frequencies are going to the "Small" setting speakers (everthing above the sub crossover setting)?

Thanks for your help.

 

[MDS]

Is this the case with any similarly labeled subwoofer (Mine is a Pinnacle Digital Sub 600)?

I can't say for sure because I have never seen a Pinnacle sub [I'll search for it and see], but I would think there is a very good chance that it is the same.

Some subs have a switch (some JBL models again) with two positions: Normal and LFE. On those types there is just one input and you flip the switch to determine if the sub's xover is enabled or not. Others have the two different inputs with different labels like yours. Still others dispense with the term LFE (because it really only applies to Home Theater) and just label the switch enable or disable. You will have to check your manual to be sure, but I'd bet anything that the input labeled LFE disables the sub's internal xover.

My receiver does not have a selectable crossover frequency for the mains and surrounds - just a Small and Large choice. The subwoofer crossover can be set between 80 and 120Hz. Does this also control what frequencies are going to the "Small" setting speakers (everthing above the sub crossover setting)?

That is the normal case - one global xover that affects all channels. Yes, the xover affects what frequencies get sent to the Small channels. Any channel set to Large gets the entire full range signal. Any channel set to Small gets the frequencies above the xover [actually the xover "rolls off" the signal starting slightly above the frequency, but that is another topic. ].

 

[AverageJoe]

Great information. Thanks.