Listening a few hours. Overall exterior absorption is an improvement. I will have to work on placement and sizing. I got better rounded images and spatial cues in the recording space plus more depth in soundstage.there was a bit too much mid bass muffling but better with 3M absorber thsn without. I was using a little different size than you. But was width of display and two 1/4 inches deep. It was a power cord tuning ring remnant I cut chunks from for covering P20 display ICs.
I have a bigger absorber chunk I pulled from DS I used as floor to lid Display shield but has dried out adhesive. I will experiment using pieces of that. My guess is the display is a EMI source for that Edcor Transformer on Analog card below it. Curing it’s emissions by absorbing definitely helps with the brightness I am sensitive to in this last firmware.
I measured and the square I used is 2 3/4x 2 3/4, not 2.5x2.5. I also have a 3x3 and a 2.5x7 absorbent left so I can try some different placements tomorrow.
No question the sound is smoother and fuller. Good to know the absorbent is helping your system too. The preferred placement and sizing may be different than mine since I have not heard the brightness in my system like yours.
? The analog output transformers are on the opposite side of the box from the display. The display is close to the power transformer. Don’t get me wrong, dampening EMI from the display is a good thing.
Thanks for clarifying. I had hard telling what that power transformer was from photos previously in this thread, but it did seem large for an 4400. I was expecting a toroidal. Yes that means display emissions could be affecting many of its different voltage outputs inputting noise into recipient DC circuits.
If we can quiet the display with absorber it is a sizable noise floor drop just from lid placement.
I got myself turned around looking under digital board at the analog board in the other mk2 picture thread. Thanks for clarifying.
These photos will help with my 3M absorber trials. @dchang05 I will cut a rectangular piece that covers back half the toroidal transformer where the wires come in. Set diagonally Along with a display piece scalloped not to interfere with side of power transformer
@tedsmith The edcore transformer i used a shielded AB7010S 3M absorber in the DS to encase those. I think the output transformer shields were beneficial to my system. But I have line array speakers with multiple drivers for mids and highs and encapsulation of 4400 output transformers with absorber and shield did not degrade highs for me as jkrichards observed in his system in DS mod thread. So I may need to encapsulate Edcores in mkII or install the Lundahls that are encapsulated in a can.
The line arrays can be a bit hotter than tweeter ribbons like Darren had in FR20 to pick firmware load of MKII.
Benefits and penalties of line arrays and newer technologies to overcome penalties is explained above pretty well. But in Audio there is never a free lunch and you pick your poison with speaker technologies and try to balance elsewhere. There is no perfect speaker until a single driver can cover all frequencies and have good dispersion and uniformity in distance output. That is physically impossible. So it still boils down to matching equipment and or using sophisticated DSP to achieve a better balance both of which have price and performance penalties.
This afternoon I will try different layout based on your observation and Ted’s pictures. My original placement does not look like the optimal one. Thanks!
I am going to also put a rectangular piece on exterior lid running the length of the ribbon cable from front display where it plugs into the digital board it is also transferring display noise direct to orange and yellow power wires to the analog board from transformer by touching them. . I don’t like the other thinner ribbon cable going to the display selector wheel the way it is touching the power transformer windings either. It is possibly inducing noise directly in the windings laying on top of them it is also really close to the other cable.
When I have time to go internal for mods the ribbon cables will get absorber square’s adhered an pulled as far as possible from transformer.
Worth every penny… Unless my dentist or oral surgeon objects for a medical reason, my days of opting for a root canal and crown are over (in the event I am unfortunate enough to face the choice again).
There’s always time to upgrade later. I would make similar choices for health, i max out a health savings account to cover those unexpected needs. After retirement that luxury ends. .
I may try a ribbon cable square of absorber on the MKII floor awhere it touches. It i better to absorb the noise early
I measured from the edge of face plate to the middle of screw, and it is about 3.5". I made some adjustments to the absorbent sheet placement. The square is three-by-three, and the two small ones are two-by-one. The five inches of two pieces starts from left of the screen to the right edge of controls. the three-by-three covers up to 1/2 depth of the transformer, but not the power cables on right. This layout removed the slight mid-bass murk and kept the fullness and soundstage. I like it better than last night and I will keep this one for the time being.
I made another change, and it brought more magic back without adding murky mid-range. I replaced the 2x1 in the back with 3/4 x 3.5 (because I have one), so it extends more towards the back. This is to cover more of the flat cable from the display.
Okay, I hit the sweet spot in my system. I will leave it alone for real this time.
When I covered too much transformer the murkiness showed up. The coverage of the transformer will be the key. Interestingly, when i extend too much of absorbent on the flat cable the sound becomes thinner. So, you can play with these two parameters and find the balance for your liking.
