[maty]

I can not view any resonance in any of these KEF coaxial aluminum speakers:

KEF Q100 (my speakers in near field in second equipment with PC) - 86 dB. 4.7 Ohms minimum.

-> http://www.i-fidelity.net/testberichte/hifi/kef-q100/laborbericht-kef-q-100-seite-5.html

KEF LS50 - 85 dB. about 4 Ohms minimum.

-> http://www.stereophile.com/content/kef-ls50-anniversary-model-loudspeaker-measurements

[Danny Richie]

Maty,

If you are looking for break up or ringing then look for it in the spectral decay rather then the impedance plot.

Looks like some internal reflection issues down low and just one area of ringing up top in the 8 to 9kHz range.

[maty]

Little resonance at 8 - 9 kHz

The resonance not seem to be important, I'm not an expert. If it were it would also appreciate in the impedance curve with a discontinuity in the curve I think.

What do you propose to reduce it?


Internal reflexions about 500 Hz

Regarding internal reflections, years ago I bought a big roll of material sold in Spain: Tecsound SY70

-> https://nauscopio.wordpress.com/tag/tecsound-sy-70/

-> http://www.texsa.es/pdfproducto/pl39/productos/id63/tecsound-sy.htm

DESCRIPTION

TECSOUND ® SY is a high density polymer-based, asphalt-free, synthetic soundproofing membrane, that offers good acoustic insulation in different building elements. It is equipped with a self-adhesive layer, to allow its direct application on the majority of building surfaces...

[Danny Richie]

Little resonance at 8 - 9 kHz

The resonance not seem to be important, I'm not an expert. If it were it would also appreciate in the impedance curve with a discontinuity in the curve I think.

Not always.

What do you propose to reduce it?

First you have to identify the cause.

Internal reflexions about 500 Hz

Regarding internal reflections, years ago I bought a big roll of material sold in Spain: Tecsound SY70

-> https://nauscopio.wordpress.com/tag/tecsound-sy-70/

-> http://www.texsa.es/pdfproducto/pl39/productos/id63/tecsound-sy.htm

That stuff looks pretty thin. I don't see it doing much for damping internal reflections. It looks like more of a damper for resonance control of the cabinet panels.

[maty]

You are right, sorry.

Sandwich of Tecsound SY 70 with fiberglass.

or rockwool.

[Danny Richie]

Yeah, that will help.

[maty]

First I want to change the capacitors and resistors. And the wire in one section:

After, maybe, tecsound + fiberglass/rockwool and... my last secret weapon, a shaped polymer putty used to add mass and eliminate resonances in the AV Marantz SR400 (bought like second hand by €115 at home => cheap: no fear to experiment).

[Danny Richie]

Changing out the binding posts to tube connectors will be a big improvement as well.