Synergistic Research HFT + FEQ

Years ago I read about glass and similar materials
as they apply to vibration control. I have had excellent
results with pieces I have bought from Prism Research Glass, Inc.
in Raleigh N.C.

I use the sixteenth inch thickness of Quartz glass discs
in conjunction with vibration control pieces, such as Symposium,
BDR, and Aurio. I place the discs on both sides of these pieces,
making a sandwich of them, so that the Quartz glass has contact with the
bottom of the speaker or electronic piece and the shelf.
It does change the sound, for the better, IMO.

I also experimented with DIY HFTs, and found that, by breaking
the discs into smaller triangular pieces (the company does not make
them smaller than 2" discs, I think) they provide "support" for the HFT.
I roll a thin bead of BLU Tack and affix it to the open side
of the HFT. Then I attach it to the Quartz glass, and affix the
Quartz glass to the wall, for example. On the back of the
Quartz piece is either a piece of double sided Scotch tape or
a small circle of Blu Tack. I can hear an improvement this way, versus
simply placing the HFT directly to the wall. I think the Quartz glass might
be "energizing" the movement of air?

Ozzy - I own 10 HFTs and a FEQ. They are crazy good so your DIY version being even better really intrigues me. I understand you use 1/8" copper caps. I found the Hareline cones on Amazon. You said to use the "large" cones. The "large" cones are 1/4" according to Amazon. Is that the correct ones to use? The other options are medium at 7/32", small at 3/16" and x-small at 5/32". Yours appear to fit so well I just want to make sure I order the right cones to fit the 1/8" caps. Thanks again Ozzy!

FYI - Ozzy confirmed via PM that it is the 1/4" large cones he used with the 1/8" caps.

FYI - pay attention to ozzy! I thought he made a typo so bought some 1/4 inch caps and they are way too large for the cones. Go figure. Turns out the 1/4 inch caps spec out at around 3/8 in.

Hi all,

I know that this is a (very) old thread, but I have been experimenting with DIY HFT clones built exactly to ozzy’s directions (I think) and am having unexpected negative results. I started with 5 of them in the SR Stage 1 config, added 5 more according to the SR Stage 2 config. They are very powerful in their effect. The highs became excrutiating in both configs. I move them around on the wall, mostly moving them progressively downward toward the floor, and noticed a change in tonality with each movement, but the high-frequency ringing was still killing my ears.

I then tried them on my room’s rear wall (only) and am liking the effect, moving the soundstage forward and adding perceived space between and behind performers. I had exactly the same experience with my Shakti Hallographs. Didn’t work well in the same room’s front corners (behind speakers), but work very nicely in the rear corners (behind my listening position).

I have the supplies to build 20 more and am hoping for some advice from those that are using them successfully around their room.

Best to you,
Dave