I can't speak definitively about other amplifiers, but I'm assuming results will be the same or similar with other (good) amplifiers as with my TABOO.  If so, run... don't walk to your keyboard and place an order for the HDT upgrade kit. Yes, it's that good, and it makes an overall improvement to the sound of the HDT's that is far and away beyond the meager price of the kit, or the 2 hour installation time.

If you also own a TABOO, you're gonna laugh yourself silly when you hear the modded HDT's in TABOO "Lucid mode".

In either mode...

1) expanded sound stage, speakers dissappear more if not completely

2) better detail/microdynamics - I know it's a cliche, but the saying of hearing things in recordings never heard before... it applies in spades here.

:D

P.S. Don't forget to felt the phase-plug as detailed in the HDT tweaks thread.

-Brad-

Brad,
What does this new tuning do for bass extention and evening of the upper end shout, if any?
John

I have not had the drivers gel waxed yet and am not sure I will. I'm very happy with the way they sound.  Steve says the gel wax is supposed to smooth out the "shout" but I don't really hear a "shout" with my room/setup. We'll see after many more hours and days of happy listening

Corey, why do you keep talking about a zbox. I don't see why I would need a zbox.  I don't think it would add much to my source and preamp combo.

I'm leaning toward building my HDT's in the MK II version as I've always been partial to ribbon tweeters, as well I have a CS to mate them to.

Actually, I have both sets of OPT's.
The original (non EX) set are in it right now.  It leaves all my options open but definately gives me too many choices.  :)

Jason

I'm happy with the alt tuning, but then I also get the tweak bug and I have the sickness of never being completely satified - ie, always looking for ways to get better sound.

Yes, I've thought about trying this combo out, but the 8ohm version of this driver is not very efficient.  If I make changes it would be either to stay at my current efficiency range 95-96db or to go higher.

Call me crazy, but one option I'm thinking of trying is using a FE208E sigma and an Aurum Cantus G2si ribbon tweeter.
The T/S params on the 208E is similar to the 206E so it should work OK in the HDT cabinet.

This particular combo of drivers is used in Dick Olsher's BassZilla Platinum kit to (reportedly) good effect.  I'm thinking the HDT cabinet will do a better job than an open baffle.  I bought the kit plans ($23) just to get the crossover design Dick used.  I figure it would be a good place to start.

Pic of phase plug felting

I found some Weldbond glue yesterday and installed the Alternate kit on one HDT.

After evaluation between the regular tuning and alternate tuning it took me about half a song to cut the passives out on the regular tuned slut and install the new passives on that one as well.

This is a fantastic tweak and IMO deserves production status. There is just too much chaos inside the chambers without this foam in there. The sound reflecting back into the rear cone of the FE206-M really messes up the mids and highs.

Corey