Meadowlark Blue Heron - gas tweeter leak problem?

Stefan,
My Blue Heron Audax HD3P tweeters show & have the same problem you are discribing. This gas leak problem was a defect in the design of the HD3P and will eventually lose almost all ouput as the gas escapes. In reality, it was NOT some mysterious gas as legend has it, but merely air.
The good news is, there is a fix! Yes, you read this correctly. My two HD3Ps are currently being modified repaired at Moca Audio (www.moca-audio.com) in Tours, France by an acoustical engineer (Marc-Olivier Chauveau) who specializes in Audax drivers. They are to be shipped back to me next week. The mod-repair attempts to seal off the the leak or leaks as good as possible. He said to me, the repair may last a year or longer, or maybe only a few weeks. The better news is, you can put the air back in yourself, if, and or when it begins to leak, as he attaches some small nozzle type tube on the back of the HD3P. It comes with instructions on how to do this. Unfortunately, you have to remove the tweeter from the speaker to put the air back in. (NOT disconnect the wires) The cost of the repair-mod is 60 Euros for each tweeter. About $75.00US
If this seems like too much trouble, he has developed an extremely modified Audax tweeter (TW025HE01) that is an exact replacment for the HD3P. 200 Euros each. In addition, you would have to replace the existing HD3P crossover with his newly developed crossover, which he claims mimicks the exact characteristics of the HD3P. 45 Euros each.
If you have any questions, I would be happy to answer them if I can. Or better yet, you can email him yourself at mochauveau@moca-audio.com

Best of Luck,

Michael

I purchased a pair of blue heron's on Agon with the tweeter problem disclosed. They sounded exactly as you describe with a lack of high frequency dynamics or general loss of volume. I previously owned a pair of heron i's and was able to easily identify this difference through comparison. My solution was to replace the tweeters with Scan Speak ring radiators. This process is involved but excellent results can be attained. You'll see that scan speak tweeters were used in the BH2's. First you will need to chose the Scan Speak model that has a similar diameter to the HD3P you will likely need to expand the tweeter opening in the box a few millimeters. Next you will need to get into the crossover which can be easily accessed through removing the bottom plate. You will notice that it is a 1st order crossover and thus relatively simple. Next you will need to calculate the resistors needed to properly adjust the sensitivity in the new tweeter. I started with the Sensitivity of the HD3P and its current resistor/s to find the existing final sensitivity. Then built an resistor network around the scan speak to result in the same final sensitivity. Additionally, the HP3P makes use of a transformer which will need to be removed. Another option is to use a L-pad which is basically a variable resistor that you can dial in to your liking(Would require more box surgery and would likely be sonically inferior). Hope this helps it worked our very well in my system.

Hi Michael, 
Your info on the HD3P replacement is very helpful. I have Meadowlark BH's with that now-deflated tweeter.
How were you able to remove the HD3P's? I removed the screws, tried to wedge them out, put a hair dryer on to melt the gasket and nothing. Won't budge, turn or anything. Is there a special tool or didn't you have this problem?
Any thoughts or suggestions wold be appreciated.
Thanks,
David

DDrave44

Try  the large screw in a small hole trick.  Basically you remove the original screws then put a single wide threaded screw that is just a bit too large for the original hole.  VERY CAREFULLY hand thread it into the tweeters plastic flange ( where the hole is ) and once it is tight ( not screwed into the baffle but tight in the plastic) you use a claw hammer's claw end to slowly pry up on the head of the screw.  Put a cloth under the hammer head to prevent damage to the baffle. 

I have done this on several BHs and even a few BH  centers.  Slow and steady pressure will release the tweeter from the keldamp gasket material.  Just be super careful not to puncture the outer mylar membrane.

Good luck with your BHs.

Mike

Mike,

Do you know, per chance, how to fix a deflated HD3P? 

Thanks a lot!
Edward