M5 Amps… shorting/replacing the front HRS feet

[JonM]

I spoke with RV earlier this week for an issue I am having and he mentioned an improvement I should try with my M5s.

He suggested removing the 2 front HRS feet, the ones that take the brunt of the weight of the transformer, and temporarily try using coupling cones instead. I could not match the HRS thread size, so I just balanced the amps on these Triad subwoofer cones I had in my parts box. I can’t report on results yet until I have the house to myself and some extended listening time. Will post again when I know more. RV made it sound like eventually all M5s will come this way and there will be a factory upgrade kit for us.  
 

Excuse any and all dust bunnies which may or may not be in pics.  My temp cones are taller than the rear HRS feet too.

Edited December 2, 2023 by JonM

[Richard Vandersteen]

3 hours ago, JonM said:

I spoke with RV earlier this week for an issue I am having and he mentioned an improvement I should try with my M5s.

He suggested removing the 2 front HRS feet, the ones that take the brunt of the weight of the transformer, and temporarily try using coupling cones instead. I could not match the HRS thread size, so I just balanced the amps on these Triad subwoofer cones I had in my parts box. I can’t report on results yet until I have the house to myself and some extended listening time. Will post again when I know more. RV made it sound like eventually all M5s will come this way and there will be a factory upgrade kit for us.  
 

Excuse any and all dust bunnies which may or may not be in pics.  My temp cones are taller than the rear HRS feet too.

JonM, did it reduce the mechanical vibration?  RV

[Delkat]

By mechanical vibration, are you referring to the low level hum from the transformers?

[Holmz]

It could also be “coming into it” from the floor, rather than “going out” to the floor.??

[JonM]

7 hours ago, Richard Vandersteen said:

JonM, did it reduce the mechanical vibration?  RV

It does seem slightly less, yes. Definitely not eliminated but better.   You would think of the cones were threaded in it would be better still. 

[Richard Vandersteen]

2 hours ago, JonM said:

It does seem slightly less, yes. Definitely not eliminated but better.   You would think of the cones were threaded in it would be better still. 

JonM, it would help slightly but it looks like the DC blocking module is your only solution.  I had this happen while running up a pair of M5's and found an electric space heater on low heat caused the problem.  Found they use a diode and use only half wave for low heat!  R core transformer not happy.  RV

[JonM]

8 hours ago, Delkat said:

By mechanical vibration, are you referring to the low level hum from the transformers?

Yes

[JonM]

5 minutes ago, Richard Vandersteen said:

JonM, it would help slightly but it looks like the DC blocking module is your only solution.  I had this happen while running up a pair of M5's and found an electric space heater on low heat caused the problem.  Found they use a diode and use only half wave for low heat!  R core transformer not happy.  RV

I will keep chipping away at it. I did try loading up one of the two DC blockers I bought to try with both M5s and even both Quatros but it didn’t seem to improve. 

Edited December 2, 2023 by JonM

[JonM]

47 minutes ago, Richard Vandersteen said:

I had this happen while running up a pair of M5's and found an electric space heater on low heat caused the problem.  Found they use a diode and use only half wave for low heat!  R core transformer not happy.  RV

I haven’t been able to find a smoking gun like that. I closed every breaker in the house except the audio-dedicated ones and had no change. Maybe a neighbor or the ABB box by the street?