What is the ideal tweeter height....

[rossman]

...in relation to your ears.

I was always under the impression that tweeters should be level with the ears.

My latest experience would suggest not. I picked up a pair of generic square section tube open frame stands, about 25 cm tall with only a single column at the front centre for £2 yesterday. These should not work very well as far as I can see but I think my speakers seem to sound better than when I have them on Heybrook stands at around 50cm with the feet I have on them. The tweeters would be ear height when sitting up straight but gradually be higher as I tend to slouch through a listening session.

Is this a speaker/stand match issue or a tweeter height issue?

[Macca]

Speaker will be closer to a room boundary (floor) on the lower stands, that may make a difference to overall response.

How far away you are when listening will also be a factor. The further away the less difference the height of the tweeter will make.

It is usually advised to have tweeter at ear height but it is a bit of a generalisation. For a 3 way speaker you really want the mid at ear height which on a lot of speakers will put the tweeter a good six inches above ear height.

If you've never done it disconnect the tweeter whilst music is playing and be amazed at how small its contribution is. Most of what we assume the tweeter is doing is actually the mid or mid/bass driver.

[Reffc]

Tweeter should be at ear height for smoothest on-axis response in general but a lot depends upon:

1. tweeter used;
2. Driver configuration;
3. Crossover design;
4. Boundary effects and room.


The generalised tweeter at ear level is correct for a tweeter of good design, using a well designed crossover in a room and listening position where there is no lift on the room power transfer function (summed response) at the listening position and where the speaker is designed for a nominally flat lobing pattern.

Taking each point:

1. Tweeter response: Different tweeters have varying on and off axis responses, so some are lifted in the treble (sometimes to counter the F-M effect....see below for more on this), some have a spiky response with lifted mids and some are nominally flat (ideal). Off axis response varies too (see below for more on this).

2. Driver and baffle configurations affect lobing which is the dispersion pattern of the loudspeaker. Typical tweeter above woofer lends a slight dip in the lobing field which lends itself to good vertical dispersion if the speakers are slightly lifted above axis, but result in drop in HF response when listened to above axis. Tweeter below woofer has the opposite effect and sounds better seated or standing (since most people dont lay on the floor listening!). MTM configuration (mid/tweeter/mid) as with LV speakers results in a nominally flat lobing pattern so they must be listened to at ear at tweeter height for correct summed response.

3. Crossover design together with drive unit: This affects (for 2 and 2 1/2 way and 3 way designs) response at our most sensitive hearing region which exists between 700 Hz and 5KHz. Most tweeters are crossed over in this region. Large phase differences in crossovers much under 3KHz are audible and if the summation isn't flat, that too can be audible. Add to that perceived brightness if the sensitivity isn't matched to the mid/woofer correctly and some speakers can sound better off axis than on!

4. Boundary effects and room - Human hearing is subject to a thing called the Fletcher-Munson effect whereby hearing sensitivity falls off below 700Hz and above 5KHz at a (high) threshold of say 45 to 50dB, sensitivity only returning on axis to something resembling flat at 100dB(A).

Problem is we can't listen at programme level at 100dB as we'd become deaf quite quickly, so most speaker designs (quality speakers where thought has been put into this) are optimised for 75 to 80dBA programme level. This is the level that the measured response is designed to be optimally flat at the listening position so that when a signal is introduced at source, we hear the output with the dynamic swings as intended by the mastering engineers. That assumes that they haven't compressed the crap out of the music!

A typical room will have both a reverberant field and an absorption factor depending on furnishings, finish and dimensions but generally, in room can be higher due to the fact we dont live in anechoic chambers so you get a nominal summation in the reverberant field and this can often be nulled at upper HF by absorption of HF, so in-room response is typically tapered down a smidgen compared with anechoic. So, many good speaker designs will sum with a slight LF to HF slope (perhaps between 1 and 4 dB between LF and HF on axis in room and be fairly flat on-axis anechoic.

It's a minefield, BUT, in general a typical tweeter above woofer with no time alignment (in the crossover or physically) will tend to sum correctly lower than tweeter level due to the lobing effect and therefore may sound better with speakers slightly raised. For time aligned speakers (like the Raptors), they are designed for the lobing to present a flat response directly at tweeter level. As with many things audio, the answer can be far more complex than anticipated...or wanted :lol:

[struth]

Speaker will be closer to a room boundary (floor) on the lower stands, that may make a difference to overall response.

How far away you are when listening will also be a factor. The further away the less difference the height of the tweeter will make.

It is usually advised to have tweeter at ear height but it is a bit of a generalisation. For a 3 way speaker you really want the mid at ear height which on a lot of speakers will put the tweeter a good six inches above ear height.

If you've never done it disconnect the tweeter whilst music is playing and be amazed at how small its contribution is. Most of what we assume the tweeter is doing is actually the mid or mid/bass driver.

I was surprised how much input the inverted tweeter on my focals has. its the most involving tweeter ive come across of type..quite like it as well and tempted to keep em.

[rossman]

Thank you all for your input, although some of what Paul said went above my head.

The speakers I am using are JPW AP3.

Paul, I did discuss sending the crossovers to you for fettling some time ago but in the end when I fitted the single wire crossovers from a pair of P1 and they sounded better than the split crossover of the AP3. It was supposed to be a temporary measure but I'm happy with the sound as it is at the moment

[Reffc]

Thank you all for your input, although some of what Paul said went above my head.

The speakers I am using are JPW AP3.

Paul, I did discuss sending the crossovers to you for fettling some time ago but in the end when I fitted the single wire crossovers from a pair of P1 and they sounded better than the split crossover of the AP3. It was supposed to be a temporary measure but I'm happy with the sound as it is at the moment

No worries Paul. The crossovers you fitted should be fine. Same woofer and (I think) same tweeter. The differences in the cabinets between the P1 and AP3 would have minimal effect on the crossovers in this case.

[cloth-ears]

Soft dome tweeters are really good at blending the HF into the sound stream. They don’t beam it like some. People tend to look at sound waves like ripples on a pond. If fact sounds waves are highly complexed three dimensional structures. Low frequencies are quite fragile and are quickly dispersed. The higher the frequency the greater is its ability to maintain its structure over distance.

Ideally the tweeters coil should be in line with that of the bass/mid driver’s coil. In other words as you look at it, the tweeter would be set further back in the cabinet. This is to allow all the sound to arrive at your ear at the same time. This is often a costly option so instead the crossover should be designed to delay the HF by a few milliseconds.

[Reffc]

Soft dome tweeters are really good at blending the HF into the sound stream. They don’t beam it like some. People tend to look at sound waves like ripples on a pond. If fact sounds waves are highly complexed three dimensional structures. Low frequencies are quite fragile and are quickly dispersed. The higher the frequency the greater is its ability to maintain its structure over distance.

Ideally the tweeters coil should be in line with that of the bass/mid driver’s coil. In other words as you look at it, the tweeter would be set further back in the cabinet. This is to allow all the sound to arrive at your ear at the same time. This is often a costly option so instead the crossover should be designed to delay the HF by a few milliseconds.

That works only in terms of phase for crossover frequency, as true time alignment is not just about physical alignment. The effect without time alignment on a flat baffle speaker without electrical delay of the tweeter is that field lobing creates a dip in the horizontal plane which gradually lifts with frequency increase and with gradual decrease, but at crossover, the sound will be out of phase and tweeter output may also appear reduced. Adopting LR2 or LR4 filters is one ideal solution since they ensure flat crossover electrical response, with phase alignment by reversal of polarity of one or more drivers (depending on 2 or 3/4 way). When used with time alignment (electrical filter or sloped baffle) they actually result in a flat lobing which is ideal. I use this to effect on my Raptor speakers for that reason. LR4 also acts to limit out of phase filtering above and below crossover point due to the steep 24dB/Octave roll off, hence the better settling time and subjective phase response of steeper filters. They also rob efficiency though and are actually quite complex to get right due to the fact that few combinations of tweeter or woofer behaves in a truly linear fashion at crossover, so LR2 tends to be the favoured choice of many designers, and results in better efficiency. First order filters between mid and HF can be used to good effect at higher crossover frequencies but rarely at lower frequencies for 2 way designs since in spite of common misconceptions by those looking to profit from the simplicity, the overlap created is not phase coherent despite some of the claims about passing square waves etc, which isn't possible. Step response of first order filters is though usually better than for higher order designs, but that doesn't make them appropriate unless the x-o frequencies are much higher up the scale (eg tweeter to supertweeter etc) where the slow roll-on/roll-off areas are not as noticeable as within the midrange.

[cloth-ears]

I like you Reffc, you take what I say, dress it up in a tuxedo and send it back to me.

As a scientist I always try to keep things simple

Sit down and have a beer :cool:

[Reffc]

Willdo!

I'm a designer & engineer so deal in detail, as detail matters :cool:

[Firebottle]

:goodthread:

I enjoy reading the detail, :respect: Paul.

:)

[Reffc]

:goodthread:

I enjoy reading the detail, :respect: Paul.

:)

Thanks Alan. It's important (for me anyway) that people are given the full and proper explanation as anything else can misguide. It's all detailed stuff but for those interested, it explains properly what short and fluffy descriptions can't. People are either interested and read it or don't. It's a shame these days that some are content with mediocrity ;)