A Grounding Mod for Sequel II

[Rob in Montana]

See post below:

[Rob in Montana]

After studying the schematic, Tyu mentioned to me another possible mod for my Sequel IIs. He noted that the panel transformer was grounded to the IEC input via the bias board and felt that this would be adding noise. He suggested instead grounding the panel transformer to the negative speaker output. Here is a pic showing the transformer wires--the red one from the transformer is the transformer ground which you can see entering the board and then to the black wire I am holding. That black wire is coming off the crossover board to connect to ground on the bias board via a screw terminal on the the bias board.



Disconnect this black wire from its screw terminal on the bias board and then thread it across the crossover board toward the negative high frequency speaker terminal. Next to where the speaker input enters the board is another connected solder point. Solder the black wire in here.



I have made a few other mods around this same time and cannot ascribe any direct effects from this mod. Taken all together, this grounding mod along with the bias mod and the removal of the resistors in the transformer output have moved my Logans in the direction of increased clarity and dynamics, lowered distortion, a lowered noise floor and have revealed low-level detail and cues leading to better imaging. I have faith that this grounding mod contributed.

Thanks again to Tyu, without whose inspiration I would never have "dove in"!
__________________

[tyu]

Rob
Thanks for your time.....an the pic...it always been funny to me that if you dont have the earth grond...an most have moved away from useing it... The noise of the world..
the cet tap see in the Acoustats with it bias transfourmer 750AC...this is not good for the sound!....but if you sale ESL you have to plan for the worst case...giveing you speakers a shot of eggnog...or you dog peeing on the interface...but with this mod you can get much better sound..an you can go back if you dont like.

[tyu]

Some here would think that there is one way to do things.....Goodluck with that... but it all about geting good sound out of ESL...if you fell you have got to have The bias gronded Go for the earth...that way you have got the diff. in the bias tranfourmer out of the Audio side of the setup tranfourmer...I dont do this it noisey... The only Bias in the setup is the feed going right to the mylar.... were it holds the bias 3k-6k what ever.....sound much better ...That what Rob is doing an it sound great...thanks

[Rob in Montana]

After this mod I became aware of stray current coming back to my amp and preamp via the speaker cables from the speakers--enough to get zapped when connecting speaker cable to the amp. If you do this mod, make sure you test with a VOM how much voltage is coming back to your equipment in this way, before hooking anything up. I have Tact amp and preamp and the Tact amp negative speaker outputs are not grounded. So even if I had minimal voltage coming back, this mod would not work with a Tact amp. Other amps may be similar. Be sure to check before doing this mod!