aer md 3B and hedlund (Drive Units)

by zsolt @, Tuesday, February 20, 2007, 23:02 (3984 days ago)

I would like to get or build the remarkable Hedlund Horn. I have an AER MD 3B drivers.

Is this drivers suitable for its design?

Here is the AER MD 3B drivers main T&S parameters:

Qts: 0,5200
Vas:77,5 L
Fs:38,1 Hz

Waiting for your response!

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aer md 3B and hedlund

by Bert @, Tuesday, February 20, 2007, 23:08 (3984 days ago) @ zsolt

I would like to get or build the remarkable Hedlund Horn. I have an AER MD
3B drivers.

Is this drivers suitable for its design?

Yes, but not use the internal angled panel of the back chamber. I don't think that the driver will fit with it in place but the most important thing about this it to have created a bigger rear volume. Its easy to make it smaller later but almost impossible to make it bigger for tuning the driver to the horn.

Ciao,

Bert

--
BD-Design - Only the Best!

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aer md 3B and hedlund

by zsolt @, Wednesday, February 21, 2007, 09:21 (3984 days ago) @ Bert

Thanks for the quick response.
What do you think about the ideal chamber size of this drivers.
The Hedlund have a 3.1 L back chamber.
Thanks !
Zsolt

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aer md 3B and hedlund

by Bert @, Wednesday, February 21, 2007, 11:21 (3984 days ago) @ zsolt

Dear Zsolt,

What do you think about the ideal chamber size of this drivers.

I never tried that driver in the Hedlund but the TS-parameters are not too far from the AERmkI and that one needed to full volume. Best is to finish it all and try filling the chamber and listen if that gives improvement.

Bert

--
BD-Design - Only the Best!

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aer md 3B and hedlund

by zsolt @, Wednesday, February 21, 2007, 12:19 (3984 days ago) @ Bert

Thanks Bert!
I will do this method.

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aer md 3B and hedlund

by unknown, Wednesday, February 21, 2007, 13:50 (3984 days ago) @ zsolt

Hi Zsolt

I ran Hornet Hedlunds with EAR Mk1s for a while, so the following may help.

Very early Hornet Hedlunds had a deeply recessed cut out in the front panel for the driver, and this restricted clearance with the rear sloping panel at the back of the compression chamber as Bert described.

Later Hedlunds like mine set the drivers in by only about 8mm which was plenty to install the EAR Mk1s and also my later Lowther DX4s without problem.

If you are building from new and have deep (large) drivers then you could fit the drivers flush on the front panel or even construct it slightly forward to give the drivers the clearance they need. All this will of course give more volume to the compression chambers.

In my case the EAR Mk1s needed more compression chamber volume than the standard horn. To achieve this I cut out three 2inch holes into the normally sealed chamber that sits below the compression chamber. This worked perfectly.
When I changed to DX4s I glued 3 cut out circles of wood back into the holes and the chamber was restored to normal.

Hope this helps.

Chris

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aer md 3B and hedlund

by zsolt @, Wednesday, February 21, 2007, 14:17 (3983 days ago) @ unknown

Hi Chris
Thanks for your advice!
zsolt

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