Alternative application of SR HFT

Last night I had friends over listening to music and checking out the new SR Atmosphere mini. I had extra HFT's laying around and we were trying different placements and one that really stood out was an HFT placed on top of the 5Y3GT rectifier tubes in my PrimaLune prologue 8 CD player and on the 5AR4 rectifier in my EICO 2050 integrated amp. Just sitting on top of the tubes made quite a difference for the better with improved clarity and expanded soundstage.

I'm thinking a high temp adhesive to securely attach the HFT's to the tube would improve things even further but I'm hesitant to go that far and it's quite impressive with them just sitting on top as is. I'm going to try them on the KT88's in my MC275 next to see how that application works out.

If you use a tube component in your system I would highly recommend you give the HFT's a try and see what you think.


Interesting. I have other fish to fry right now, but I have had truly excellent results with the HFTs in my room and on my speakers among a number of other SR products. I will keep it in mind, as I have contemplated introducing damping to my EL-34s in the past....
Someone (perhaps from SR, I think) did say to me at one point to try ECTs on the amp chassis near the base of tubes, but not on the base itself. They did not say anything about putting them on tubes themselves. I believe that HFTs are not non-conductive, while ECTs are non-conductive. So some care is probably appropriate.  I find that tube dampers such as Herbie's HAL-O III dampers do a very good job with tube vibrations and resonance.  I use 2 or even 3 of those per tube. I tried ECTs near the tubes, but have found them more effective around digital circuits.  Also quite good on cables and electronic circuits.
Great discovery. I will try this today on my SET amp and OTL headphone amp. Loctite (Home Depot) makes a high temperature glue (GO2 GEL) that I used to attach 9 HFT's on the front windshield of the Honda MiniVan.

 I now have a realistic soundstage in front of me while driving. It is quite rewarding to be driving "towards" a piano playing Mozart on the way to work. The improved soundstage allows me to enjoy a lot of quiet acoustic music that in the past did not sound good in a car environment.

I do use Synergistic Research ECT's (Electronic Circuit Transducers) on my amp chassis. Good places to try are:
Near the driver tubes
Near the signal tubes
Near the on-off switch
Near the volume control

I did not have improvement with ECT:
Near the output tubes
Near the Transformers

David Pritchard


I spent the morning evaluating the sonic changes placing a Synergistic Research HFT ( High Frequency Transducer) on the rectifier tube of my 300B SET amp. Big WOW! What a wonderful improvement in vocal clarity and increased depth of soundstage. The decay of notes is more relaxed and yet there is excellent harmonic textures. The music is more alive.
The sound now gives the impression that the amp has more muscle and better control. 

It certainly is creating a bigger change and for the better than my tube rolling 300B tubes. 

So if you have a spare HFT place it on your amp's rectifier tube and enjoy.

A super big thank you for this suggestion.

David Pritchard
I too believe you are right about ECTs anyway near the rectifier tube in my DAC.  I have a number of ECTs in the DAC and I moved one much closer to the rectifier tube placing it upside down on the cover plate inside the DAC hovering above just around the 6CA4 rectifier tube.  I believe it is making a nice difference.  Thanks.