Audax HD-3P DIY regassing.

Dedicated to those large boxes at one end of the room
Post Reply
JohnG
Old Hand
Posts: 418
Joined: Sat Mar 25, 2017 10:59 am

#1 Audax HD-3P DIY regassing.

Post by JohnG »

I am suffering from insomnia at the moment, too much on my mind.
I hope it offers a benefit to a HD-3P owner who has a gas spent pair tucked away for safe keeping.
This morning in the early hours I awoke with my grief and redirected to my newly purchased speakers, with their spent gas HD-3P tweeters.
I recalled a thread that interested me in the past, as I had always been fanciful to the Gold Dome Peizo's
The Guy who was based in America, claimed he had repaired his own set of HD-3P, he let you know there was a air intake point behind the sticker on the rear of the unit, and that by using Blutak, he had regassed and sealed his drivers, this was about three months into his success with no gas loss.
He never elaborated on the procedures, or provided a method to carry out the tasks.
With this basic recollection of investigations in hand, I got to the task, and at this moment I have two regassed HD-3P tweeters sitting on my kitchen table, awaiting my wife to awaken, " more on that later ".
YOU ARE WELCOME TO FOLLOW MY METHOD AT YOUR OWN RISK.
Step 1,
Put the tweeters on a work surface face down with a very soft foam as a protection for the gold peizo diaphragm. Mine has a foam donut glued to the
metal housing, so the peizo was elevated above the foam for extra security.
Step 2,
Remove the sticker that shows model and serial number on the rear face of the tweeter. You might as well clean all gum residues of, vinegar will
do this, " I used Citrus Spray Cleaner "
Step 3,
Now the sticker has gone, a small slot head screw will be revealed. Choose the correct fit screw driver, take the driver in one hand to hold
firm and undo the screw, " mine were not overly tight and released with little force "

Note at this stage when the screw was removed, I gave the screw hole a couple of "kisses of life", there was no change to the gold diaphragms
surface. I them got my Giottos camera dust blower and placed the nozzle firmly on the inlet, pressing the rubber bulb for air pumping, I could
see no movement to the gold diaphragms surface.
"Hmm" "Ha" "Ha" "there must be a non return valve down inside the inlet"
Step 4,
THIS IS THE RISKY BIT SO A CAUTIOUS APPROACH IS REQUIRED. Do not be put off though, I am a stereo type BUFFOON, and I did it with no
unhappy experience to report.

I used a 1.5mm Allen Key as a probe and gently felt inside the inlet, about 5mm down the shaft I hit a resistence, I applied a tiny bitof
increased pressure to the Allen Key and felt the resistence dislodge. As soon as you feel the resistence dislodge REMOVE THE PROBE.
DO NOT DO THIS NEXT STEP, LET MY CURIOSITY SETTLE YOURS.
I carried on allowing the Allen Key to travel down the shaft, checking for further resistence. It travelled to the point it hit the Diaphragm,
at this point you will let out all types of expletives, it is unneccessary.
Step 5,
I placed the Giottos Blower over the inlet hole and give the buld a gentle press, the gold diaphragm immediately reacted, re-inflating to a
crinkle free state. " EUREKA" " Il Faut Casser Le Noyau Pour Avoir L'amande" " WTF"
The Giottos is not a good tool to use for inflation when the screw is placed back in the air intake hole.
Step 6,
I placed the screw back in the hole, did it up to the point where a "kiss of life" would re-inflate the gold diaphragm to a crinkle free state.
I put a piece of the tweeters frame air seal compound under the screws countersink head and sealed the air intake by fully tightening the
screw.
The tweeters are now five hours re-inflated and as smooth as my wifes teen years derriere. :drunken:
Step 7,
This is now Theoretical, " or to be tried as a better solution"
When Wifey awakes, find out where my PTFE Plummers tape is hiding itself. I feel this will be a much better substance to seal the air intake
screw, in place of the tweeters air seal compound. A added plus point is that it will not glue the screw thread like other air seal options
might do.
I know from another investigation into the HD-3P there is a professional re-gas service on offer at about 100 euros a tweeter. It will be
returned with a device to allow a user to carry out a easy re-gas if required at a future date.
I like this as a option, I will state a few reasons why.
You will have a better control of the surfave tension that is set on the Gold Peizo Diaphragm.
You will be able to enjoy your tweeter at its best for multiple years, with little concern for gas leakage.
With the correct length of air intake pipe you could put your tweeter into any enclosure and create a easy point of access for any future
maintenance.

Here are my thoughts on how to create a easy re-gas device.
The Agricultural Industry have pneumatic air intake valves for machinery wheels. These look like the common air intake valve for any
vehicle with pneumatic tyres, but are supplied as the rubber coated valve housing with the pin operated non return valve. They have a
rubber flange at the base of about 50mm diametre.
This flange could be glued onto the back of the back of the tweeter using a silicon adhesive, creating a good quality air seal.
A standard bicycle pump flexible hose attachment of a chosen length, can be attached to the pneumatic valve and routed to a place where
a easy connection can be made if there is a need to to a maintenance refil of the gas. Again all connections can be sealed with PTFE tape
and the end of the flexible hose where the pump attaches would need to be capped of with a PTFE seal.
It would seem the down side to this maintenance solution would be that the Cavity on the tweeter to be filled with air and the air hoses will
all be holding a charge of the air.

A minature non return check valve could be attached to a nut that has the matching size to the valves thread. The nut is bonded onto the
rear of the tweeter using a high quality silicon adhesive. The valve would be connected to the nut using PTFE tape, and a extension hose of
a individuals required length could be routed to a easy access point for maintence purposes.


Any thoughts or proposed solutions to a easy access maintenance device are going to be well received.
User avatar
IslandPink
Amstrad Tower of Power
Posts: 10041
Joined: Tue May 29, 2007 7:01 pm
Location: Denbigh, N.Wales

#2 Re: Audax HD-3P DIY regassing.

Post by IslandPink »

Crikey - good effort. I never knew there was a means of re-pressurising them - thought that once they'd gone, they'd gone.
"Once you find out ... the Circumstances ; then you can go out"
JohnG
Old Hand
Posts: 418
Joined: Sat Mar 25, 2017 10:59 am

#3 Re: Audax HD-3P DIY regassing.

Post by JohnG »

These tweeters are now in re-gas stage 2nd attempt and they are exceptional, I have began replaying the CD's I put through them yesterday, the difference is Jaw Dropping. Norah Jones, Duffy, Sea Sick Steve, Jack Johnson and the Foo Fighters. It is a WOOW! with abig :D to all replays .
The Foo Fighters showed the biggest improvement from my memory, the vocal were at the back of the sound stage and the whole performance was alittle flat. Now I,m nailed to the wall through the new found projection with the Singer in your face.
I am going to write part two of the re-gas method so my 2nd attempt to a success is out there.
Post Reply