AE Lambda Midbass 10 Project?

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Hi John, I came to this thread googling for 10" midrange. I'm looking for high efficiency from about 250 to 3-4k (94+db). I read all thread and the TD10M is the driver that come closer, right?
The 6.5" mid has been made? I could alternatively use a pair of those, if it is efficient. Parameters?
 
John,

The Altec sound is popular. BuyDecision = underhung motors, low Mms.

There is increased interest in 8" and 10" speakers with underhung motors and high'ish efficiency.

Have you built a TD10LO, the Lynn Olson underhung motor with the 10M cone?
OR... can you estimate the TS parameters of a TD10LO?

Do you have any new information on a TD8M or TD8LO?

Do you plan a high'ish efficiency, full'ish range 8" speaker. Mms~ 9-10grams. No whizzer!
 

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Hi John, I came to this thread googling for 10" midrange. I'm looking for high efficiency from about 250 to 3-4k (94+db). I read all thread and the TD10M is the driver that come closer, right?
The 6.5" mid has been made? I could alternatively use a pair of those, if it is efficient. Parameters?

Crossing at 3-4KHz is quite high for a 10" driver. I will have a quite narrow pattern by that point. Typically you won't want to go above 2KHz with any 10" unless it is for a very direct listening position. If you are only needing a very tight pattern, then the TD15M is actually far smoother to that 4Hz region.

The TD6M's are also an option. At 93.5dB they are only .4dB lower efficiency than the TD10M. The difference is that they will have much better dispersion by 3-4KHz due to the smaller diameter. A single TD6M has enough displacement to reach 118dB from 250hz on up. A pair will give 6db more.

The biggest question is what are you crossing to at 3-4KHz. Typically you will want to bring that point down quite a bit lower. If you do have to cross at that point, possibly an MTM with 2x TD6M may be a good option.

John,

The Altec sound is popular. BuyDecision = underhung motors, low Mms.

There is increased interest in 8" and 10" speakers with underhung motors and high'ish efficiency.

Have you built a TD10LO, the Lynn Olson underhung motor with the 10M cone?
OR... can you estimate the TS parameters of a TD10LO?

Do you have any new information on a TD8M or TD8LO?

Do you plan a high'ish efficiency, full'ish range 8" speaker. Mms~ 9-10grams. No whizzer!

The problem is that underhung motors and high efficiency do not go together. In an underhung motor you use only a portion of the flux in the gap at any time. In the case of the Dipole woofers you use 1/3 of the flux as the coil is 1/3 the length of the gap. The LO series use the same coil but I shrunk the gap from 1.5" to 1.125". Because there is the same overall amount of flux, the density is higher giving more efficiency. This means less Xmax though. Once that happens they cannot play loud enough at low frequencies. There are tradeoffs to everything.

Doing an LO10 is possible but only brings efficiency up to about 89dB 1W. The TD10M is still far more efficient.

As far as the "sound" of the Altec goes, I am not personally interested in recreating that. I go to great lengths to make sure that the woofers I build are free from resonance from surrounds, spiders and cones. The motor design is the biggest contributor though. The linearity of the BL and Le curves are responsible for very low distortion. The woofer should be able to accurately reproduce the signal input with the least coloration possible. This is however not the case with most drivers especially many of the vintage type drivers. If nothing is done to handle eddy currents and the inductance modulation, the distortion skyrockets. If you look through the measurements on the Driver Vault page you can compare the drastic difference in distortion between the TD12M and Altec/GPA 414. The 414 has literally 10x the distortion measured at 150hz at 100dB! From 200hz to 2KHz the 2nd and 3rd harmonic distortions of the 414 are upwards of 10dB higher than the TD12M. This is all attributed to motor design and evident in the Le(x) measurements there. These are things that give the 414 it's sound and not something I would want to put back in.

https://sites.google.com/site/drivervault/driver-measurements/tang-band-75-1558se

John
 
The TD6M's are also an option. At 93.5dB they are only .4dB lower efficiency than the TD10M. The difference is that they will have much better dispersion by 3-4KHz due to the smaller diameter. A single TD6M has enough displacement to reach 118dB from 250hz on up. A pair will give 6db more.

The biggest question is what are you crossing to at 3-4KHz. Typically you will want to bring that point down quite a bit lower. If you do have to cross at that point, possibly an MTM with 2x TD6M may be a good option.

Yes, two TD6M are a better option for me. I'm flexible with the XO point, but I personally like it higher than 3k (tried with 8").
Can you tell me all t/s parameters and price for it?

Kind regards
 
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