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[Conrad Muzoora]

Dear All,
You may remember my older post about these boxes, they're probably close to 30 years old and i got them 3 years ago. I swapped out the aftermarket diaphragms installed by the previous owner and installed new OEM DH7, ND6 -16ohm diaphragms and the difference was like night and day. I recently got a sweet deal on eBay and picked up 16 (sixteen) nd6-16ohm drivers with working original diaphragms at a cost of 100$ each (about half the price of the diaphragms alone) and am considering swapping out all the 16 DH1a in all my 8 boxes (This will save me 26kg per box and i can sell the heavy DH1as).
Any reasons why not to do this?? I am sure the sound quality will be fine but not sure if this will change other important variables, like centre of gravity while flown etc.
All opinions are welcome.
Conrad

[Casey McDonald]

Dear All,
You may remember my older post about these boxes, they're probably close to 30 years old and i got them 3 years ago. I swapped out the aftermarket diaphragms installed by the previous owner and installed new OEM DH7, ND6 -16ohm diaphragms and the difference was like night and day. I recently got a sweet deal on eBay and picked up 16 (sixteen) nd6-16ohm drivers with working original diaphragms at a cost of 100$ each (about half the price of the diaphragms alone) and am considering swapping out all the 16 DH1a in all my 8 boxes (This will save me 26kg per box and i can sell the heavy DH1as).
Any reasons why not to do this?? I am sure the sound quality will be fine but not sure if this will change other important variables, like centre of gravity while flown etc.
All opinions are welcome.
Conrad

Hope I have this right - but I think that box has an MTA-22 manifold adapter (I have two boxed up somewhere).  The new ND6's should bolt onto the flange no problem.  But you may be left with a shoulder where the two join.  The MTA-22 datasheet I found says the entrance is 1.3" while the ND6 exit is 1.38" (I never got to measuring mine).  A 0.04" annular shoulder may not audibly matter?  It shouldn't reflect anything but the area expansion will be unsmooth at that point. Try a couple boxes and see what they sound like compared to original, and let us know!  Despite the above i'd still be expecting more 10khz+

[Conrad Muzoora]

Hope I have this right - but I think that box has an MTA-22 manifold adapter (I have two boxed up somewhere).  The new ND6's should bolt onto the flange no problem.  But you may be left with a shoulder where the two join.  The MTA-22 datasheet I found says the entrance is 1.3" while the ND6 exit is 1.38" (I never got to measuring mine).  A 0.04" annular shoulder may not audibly matter?  It shouldn't reflect anything but the area expansion will be unsmooth at that point. Try a couple boxes and see what they sound like compared to original, and let us know!  Despite the above i'd still be expecting more 10khz+

Thank you for this,
Yes there's an adapter that combines the two DH1as to one hp64 horn. From looking at the DH1s as mounted, they're fixed direct without the usual 1.4-2" adapter. Well, will keep u updated.
Conrad

[Art Welter]

Thank you for this,
Yes there's an adapter that combines the two DH1as to one hp64 horn. From looking at the DH1s as mounted, they're fixed direct without the usual 1.4-2" adapter. Well, will keep u updated.
Conrad

Conrad,

Your old drivers are DH1AMT, the DH1 has the adapter from 1.4 to 2". You will "only" save 16.2 Kg (not 26Kg) (35.6 pounds) per box ;^).

The DH1AMT is listed variously on EV spec sheets as a 1.3", 1.38" and 1.4"(3.56CM) exit. I measured them as about 35.5mm, nominally closest to 1.4". I'd be surprised if the DH6 is not the same exit size.

I am a bit curious about the MTA22 entrance- if it is only 1.29" (like the DH2012), it would cause a bit of reflection. I never measured one before returning 16 of them..
That said, a little reflection compared to the 90 degree bend and cramming the output of two 3" diaphragms into one 2" hole is just part of the fun ;^).

Art

[Conrad Muzoora]

Dear Friends,

Yes i did the swap,
The drivers fit perfectly and their exit is identical to the DH1aMT, approx. 1.4", no shoulder left bonding to the MTA22.
The sound is great, a tad brighter than the DH1As, i guess due to the higher sensitivity. I will tame these boxes as i get more time to play with them. Yes the weight difference is noticeable.
See attached,
Conrad

[Tim McCulloch]

Hi Conrad-

I'm not commenting on this particular project as I've not used the box...

But I'm impressed by the way your company has grown over the last 8 years and thank you for sharing that with the rest of us.

[Art Welter]

Dear Friends,

Yes i did the swap,
The drivers fit perfectly and their exit is identical to the DH1aMT, approx. 1.4", no shoulder left bonding to the MTA22.

Conrad,

Thanks for the exit size confirmation.

I noticed you are looking for ADH-6 adapters, you might look for broken DH1A drivers, and remove the 1.4" to 2" snout from them. Requires heating the screws to loosen the Lok-tite, otherwise they tend to break the Allen wrench driver or the screw...

I may have at least four units (I'd have to unload most of a trailer to find out how many of the eight I once had are left) that are functionally the same as ADH-6 if you don't find any local deals.

Art

[Conrad Muzoora]

Hi Conrad-

I'm not commenting on this particular project as I've not used the box...

But I'm impressed by the way your company has grown over the last 8 years and thank you for sharing that with the rest of us.

Thank you,
Conrad

[Conrad Muzoora]

Conrad,

Thanks for the exit size confirmation.

I noticed you are looking for ADH-6 adapters, you might look for broken DH1A drivers, and remove the 1.4" to 2" snout from them. Requires heating the screws to loosen the Lok-tite, otherwise they tend to break the Allen wrench driver or the screw...

I may have at least four units (I'd have to unload most of a trailer to find out how many of the eight I once had are left) that are functionally the same as ADH-6 if you don't find any local deals.

Art

Dear Art,

You mean its possible to remove the adapters from the DH1as that i already have??
I however wanted to sell these off and am worried that i may damage the drivers in the process,
The clones you post look good are they on sale anywhere??
Conrad

[Art Welter]

Dear Art,

You mean its possible to remove the adapters from the DH1as that i already have??
I however wanted to sell these off and am worried that i may damage the drivers in the process,
The clones you post look good are they on sale anywhere??
Conrad

Conrad,

The clones my dad (RIP) made for me in the 1990's on his lathe are for sale, but if you already have DH1A drivers, no need to buy them.

Yes, you can remove the adapters from the DH1A drivers that you have with no damage, the drivers then are the same as a DH1AMT, and could be sold as such. Since you presumably already have a quantity of DH1AMT to sell, should be no problem to add more to the sale ;^).

EV made those drivers and 2" horns to better fit the JBL dominated 2" pro market of the time.  Horns that fit 1.4" exits are now fairly common,  and may provide better sound than the 2" horns, less of a throat "pinch" reduction is a good thing.

Art

[Conrad Muzoora]

Conrad,

The clones my dad (RIP) made for me in the 1990's on his lathe are for sale, but if you already have DH1A drivers, no need to buy them.

Yes, you can remove the adapters from the DH1A drivers that you have with no damage, the drivers then are the same as a DH1AMT, and could be sold as such. Since you presumably already have a quantity of DH1AMT to sell, should be no problem to add more to the sale ;^).

EV made those drivers and 2" horns to better fit the JBL dominated 2" pro market of the time.  Horns that fit 1.4" exits are now fairly common,  and may provide better sound than the 2" horns, less of a throat "pinch" reduction is a good thing.

Art

Thank you Art,
Let me try that straight away.
Conrad

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