AE Speakers Dipole 15 or LO15 ? Need advice

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OllBoll,
You should refrain a little albeit your good intentions.

"Underhung drivers perform worse when pushed to their limits than overhung if I remember correctly."
Pushed to their limits not over their limits... maybe that's what you were thinking.
An underhung motor will have very good Bl linearity and very low distortion up until the coil hits it's Xmax point. It is almost flat like a ruler up to the 12mm one way(24mm peak-peak) Xmax. Past 12mm it will drop quickly...
John_E_Janowitz

"The Dipole15 has less xmax and is overhung, the IB15 and the TD drivers have more xmax"
You are right with the IB15:
Xmax: 18.5mm
Xmech: 25mm

Not with the TD15M:
Xmax: 6mm

Dipole 15:
Xmax: 12/13mm? peak

LO15:
Linear Xmax 9 mm (peak)
Mech Xsus 12 mm (peak)

I also love the aesthetics and maybe that's only a problem of vocabulary if I understand. I guess one of the advantage of small magnet units for you is when they are inverted, or/and have less airflow noise.
 
OllBoll,
You should refrain a little albeit your good intentions.

"Underhung drivers perform worse when pushed to their limits than overhung if I remember correctly."
Pushed to their limits not over their limits... maybe that's what you were thinking.

Yes, that is it exactly... one thing I love about forums like this is that other people can clarify where oneself hasn't been clear enough =)
 
"The Dipole15 has less xmax and is overhung, the IB15 and the TD drivers have more xmax"
You are right with the IB15:
Xmax: 18.5mm
Xmech: 25mm

Not with the TD15M:
Xmax: 6mm

Dipole 15:
Xmax: 12/13mm? peak

LO15:
Linear Xmax 9 mm (peak)
Mech Xsus 12 mm (peak)

I also love the aesthetics and maybe that's only a problem of vocabulary if I understand. I guess one of the advantage of small magnet units for you is when they are inverted, or/and have less airflow noise.

The Dipole15 and LO15 are both underhung.

The Dipole15 has 12mm one way Xmax(24mm p-p) and about 22mm suspension travel each way. It is about 90dB 1W

The LO15 has 9mm one way Xmax (18mm p-p) and about 12mm one way suspension travel. It is about 93dB 1W

The IB15 has 18.5mm one way Xmax (37mm p-p) about 22mm one way suspension travel. It is 86.5dB 1W

The TD15M has 6mm Xmax one way (12mm p-p) and about 12mm one way suspension travel. It is 98dB 1W.

While the IB15 can play lower, it doesn't have a benefit in output over the Dipole15 until below 25hz. On any reasonable size baffle, the rolloff is just to far down to play that low.

For a general rule, if someone is ok with 30hz and higher, the LO15 can have some benefit. If you are looking to get a low end that extends down as far as 25hz, the Dipole15 becomes a better option.
 
In any system like this I would be working with DSP for EQ, crossover, and time alignment. This is something some people shy away from and want to go with a passive system. There just aren't passive ways to go and correct for the rolloff and get the right phase throughout the crossover region. Something like the mindsp can work well as a simple option to experiment with. Other more high end options could work even better.

Here are 2 possible options I would look at. If it was simply a 2way or 2.5way system where the woofers had to play up to around 1KHz, I would choose the LO15. The cloth surround is free from a couple resonances that the foam surround has which would be an issue playing that high. I would use 2x LO15 per channel, bringing in the bottom woofer to start filling in below where the baffle step begins. This of course requires a 3rd amplifier channel but has some definite benefits compared to running both woofers this high. To cover down to 1KHz would require some kind of larger horn driver so the upper end wouldn't be open baffle.

For a 3way system I would use the 2x Dipole15 for more maximum output. I would cross over to the Dipole6 at the appropriate frequency based on the baffle step. This would typically be no higher than 300hz or so. At that point, both Dipole15's could be sent the same signal. I would then cross the Dipole6 to the RAAL dipole ribbon or AMT for the top end.
 
The very best bass you'll get is in the NEAR-FIELD (..if only one sub positioned very near and just behind your head with the appropriate delay for proper summing.)

It will give you these properties (assuming you sit right next to them):

1. substantially more "efficient" at lower freq.s regardless of design, but particularly well suited to a dipole/ripole/cardiod.

2. substantially more linear - with less influence from standing waves.

3. greater tactile sensation (..upper bass "punch", and lower bass "slam"). It also allows the use of drivers that have these qualities that might otherwise be a poor choice for a more typical application.

The common aesthetic I mention for such a "sub" is an "end-table" behind your listening chair or sofa, OR if stereo and only using a chair - a pair of side tables to the left and right of the chair.

Figure about a 2 foot distance to the closest "edge" of the driver (or closest driver) - the closer, the better.

This is a little off topic, but Scott I guess you say this from experience.
I'm about to work out the box and placement of a single EBS 18" sub for 12-60 Hz, mostly for HT.

Do you have any links on theory or experience of the relationship between closeness and (apart from 1 & 2) greater tactile sensation?

Thanks!
 
This is a little off topic, but Scott I guess you say this from experience.
I'm about to work out the box and placement of a single EBS 18" sub for 12-60 Hz, mostly for HT.

Do you have any links on theory or experience of the relationship between closeness and (apart from 1 & 2) greater tactile sensation?

Thanks!

Yes, from experience - but there is also a fair bit of research on this subject. (..I think JohnK at one time had something on near-field bass, but I don't think it discussed greater tactile sensation.)

As for tactile sensation, just personal experience. There probably is research on this from at least divergent fields of interest (..almost certainly with respect to "blasts" from ordinance), but I've never looked for it. :eek:
 
In any system like this I would be working with DSP for EQ, crossover, and time alignment. This is something some people shy away from and want to go with a passive system.

Actually this is one area that is over-looked by your competitors.

Specifically relating to the addition of a 2nd voice coil.

One coil can be "full range" - or integrated into a passive system, allowing integration up into the midrange and utilizing the more highly "prized" amplifier. (ie. a more "purist" approach.)

The 2nd coil can be driven by a more powerful amplifier to compensate for pressure loss, and perhaps make various corrections - which could include room eq. for a listening position.

Sort of "having your cake and eating it too". :)
 
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higher up: 15 LO vs TD15M

Hi John

To shift focus to upper bass and lower midrange, and understand the differences between your AE drivers better:

I'm soon to do an active dipole system, running 15 inch AEs, either the LO or the TDM, from about 100 up to say 550 Hz.

  • The TDM is 5 dB more efficient, but being active and not having a need for volume more than 110 dB, either should be fine.
  • (If my memory is right) both are underhung and have copper sleeves.
  • The TDM has less Xmax (6 mm) than the LO (9 mm), but both should have enough, as not being used for lower bass.

    Does the TDM also have cloth surrounds?

    Which would you recommend?

    And if I were to run up to say 1200 Hz, would the better option - smoother response? - be the TDM?

    TIA!
 
Hi Scott

I've been meaning to ask you:

“Achieving more articulate bass is often a matter of Qe”

Could you explain that. (Is more or less better?)

Is it theory or experience with some drivers you could name?

TIA!

The lower the Qe (or Qes), generally the more detail - all else equal.

Lower Qe generally exhibits greater control over the VC, particularly as you near the driver's resonance. It's about higher damping, specifically magnetic damping as opposed to mechanical.

While Qe references damping - it is a motor-based effect, and it requires a stronger motor. That higher strength motor tends to effect the entire pass-band though, NOT just near driver resonance.

Almost any driver with a lower Qe does this, and I've used several (and listened to several designs with a lower Qe).

A good example are some of the fostex full-range units like my Fostex FE166ES-R which has a Qe in the low .2's. HOWEVER, it also has other features that enhance this particular aspect: low mass vs. sd & a low damping surround. (..it's not unlike a Lowther, and unfortunately there is a price to be paid with linear decay when it comes to low mass and a low damping surround.)


Note though that this is just a single parameter - I usually don't go looking for low Qe drivers. (..the search is always dependent on the design.) In fact, I tend to prefer moderate Qe drivers (.4's) that are more efficient and that have lower mass for their Sd and have more compliant surrounds (NOT spiders, though I like compliant spiders as well - ie. higher Qm). Unfortunately these sorts of drivers have much larger Vas requirements for their Fs.

Caution: always look at Mms vs. Sd in relation to Qes. It's often the case that a much lower Mms for the same driver diameter with a higher Qes is overall more detailed than a much higher Mms driver with a lower Qes. Those higher Mms drivers with a lower Qes however tend to have more detailed bass around resonance regardless, AND the same drivers tend to have a lot of "punch" - or that upper midbass lower midrange visceral tactile sensation. Relative to their average impedance, they also have higher Bl's.
 
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After a lot of good service from John via email, thank you, i landed on two pair of custom LO15 with foam surround.

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I wonder if this is how i should wire a pair:

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I haven't wired them yet. Does anyone know how?

Depends on what kind of load your amplifier prefers. The choices you have are (assuming 2x 8 ohm voice coils)):

1# Series-parallel ( 2 coils in series parallel to the other two coils also in series ): will give you an 8 ohm load. If I'm not mistaken the diagram in the pic is series-parallel.

2# All parallell: will give you a 2 ohm load.

3# All series: will give you a 32 ohm load.

Unless you have a special amp you'd probably want to go series-parallel.
 
It is dual 8ohm: AE Speakers --- Superb Quality, Unforgettable Performance, Definitely.

LO15 have a shorter version of the voice coil from Dipole15

So, since the driver is wired in series = 16 ohm and wired in paralell with the next driver = 8 ohm in total?

I have a class-A amp with strong powersupply who delivers 50/100/200 watt pr channel in 8/4/2 ohm. (2x500 VA & 200.000 uF)

Yes exactly. If your amp can handle 2 ohm load without increased distortion then you might actually consider paralleling them all since the drivers themselves aren't 8 ohm but rather ~ 8 ohm minimum.

But in the end it you probably won't use that many watts so it shouldn't matter that much how you wire.
 
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