Lambda Acoustic Elegance 100 to 550 Hz - 15 LO vs TD15M

otto88

Member
2007-12-05 10:39 am
Hi

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

IIRC, both are underhung and have copper sleeves.
Does the TDM also have cloth surrounds?

The TDM has less Xmax (6 mm) than the LO (9 mm), but both should have enough, as not being used for low bass.

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.
Though the greater efficiency would give more flexibility re lower powered amps eg class A or tube


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

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

IIRC, both are underhung and have copper sleeves.
Does the TDM also have cloth surrounds?

The TDM has less Xmax (6 mm) than the LO (9 mm), but both should have enough, as not being used for low bass.

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.
Though the greater efficiency would give more flexibility re lower powered amps eg class A or tube


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!

The TD15m is not designed for what you want to use it for, the Dipole 15 (not clear on the difference between it and the LO15) is. Obviously it can do it to at least some extent, but AFAIK they'd be the same price. So why not get the one designed for what you are trying to do.

Is there some reason you aren't looking at the Dipole 15?

FWIW, the Dipole 15 is described as ideal for use with tube amps and will still hit something on the order of 105db wt 32 watts of power.

The Dipole 15 has an xmax of 12mm. So I'm guessing that is the foam surround.
 

otto88

Member
2007-12-05 10:39 am
You’re right, the TD15M isn’t designed for use in open baffles. But I wouldn’t be using it where the excursion is needed – to extend undistorted or higher dB in the low bass. (I already have four drivers, high excursion and high Q specifically for that)

The TDM’s much greater efficiency would allow tube amps . .
“Dipole 15 is described as ideal for use with tube amps and will still hit something on the order of 105 db wt 32 watts of power”

The Dipole 15 is only 90 dB, and i might/ would like to be able to use a currently spare tube amp (an 845 SE) of only 18 watts. And I’m after 110 dB

Tho after you mentioned the Dipole 15 being for use with tube amps, I looked it up
AE mention “Non-reactive load ideal for use with tube amplifiers”

Anyone know what spec measures or correlates with a non-reactive load?

Cheers
 
You’re right, the TD15M isn’t designed for use in open baffles. But I wouldn’t be using it where the excursion is needed – to extend undistorted or higher dB in the low bass. (I already have four drivers, high excursion and high Q specifically for that)

The TDM’s much greater efficiency would allow tube amps . .
“Dipole 15 is described as ideal for use with tube amps and will still hit something on the order of 105 db wt 32 watts of power”

The Dipole 15 is only 90 dB, and i might/ would like to be able to use a currently spare tube amp (an 845 SE) of only 18 watts. And I’m after 110 dB

Tho after you mentioned the Dipole 15 being for use with tube amps, I looked it up
AE mention “Non-reactive load ideal for use with tube amplifiers”

Anyone know what spec measures or correlates with a non-reactive load?

Cheers

A non-reactive load is one that is purely resistive (Ohms). This seems to be a good guide as to what effects a reactive/non-reactive load has.

Dummy loads - should they be resistive or reactive?
 
In reality either of these drivers could work extremely well from 100hz to 550Hz. On an infinite baffle the LO15 would be -3dB at about 30hz and the TD15M would be -3dB at about 100hz. In either case you need to compensate for the baffle rolloff with EQ. If you want flat to 100hz on an open baffle you would need 3dB more EQ with the TD15M than the LO15 at that point. This is still very manageable.

I would really make the determination based on the possible other uses. If you plan to do an open baffle where you want to go down to 30hz in the future, then the LO15 would be the better option. If you are looking at doing any kind of high efficiency vented enclosure, look to the TD15M.

Both of the drivers have good extension up to over 3KHz. You can see measured data on the LO15 here.

https://sites.google.com/site/drivervault/driver-measurements/15/ae-speakers-lo15

Both are very non-reactive loads that are easy to drive with a tube amplifier. Inductance does not change with excursion and the back EMF is shorted out by the copper sleeve on the pole as well.
 
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Hi Otto, They didn't measure the TD15M during those tests so I don't have anything directly comparable. I have done some closemic measurements showing the extended upper end, but that also has measurement artifacts from the close mic position.

http://www.aespeakers.com/pics/measurements/TD15M-closemic.PNG

At 1m and 2M the response will look mostly identical to the LO15 curves. The TD15M and LO15 use the same cone, surround and spider so they are physically very much the same. It isn't until the lower frequencies where the differences in motor strength and Q really change the response. Above 150hz the curves will be nearly identical, just about 4dB different in level.