Siemens 6Ruf lsp 28a

Frequency response of my two way speakers, Graetz typ.5400(Isophon P2132 equiv.) and Siemens 6 Ruf lsp 28a, 6dB/oct network at 2.5kHz.

Ignore red plot, see background gray plot. Gray represents peak level sweep from 20Hz to 20kHz.

Connected the sine wave generator to the amplifier, sweeped from 20Hz to 20kHz and measured by iPhone Sonic Tools APP.

Definitely, I need to do something on the dimple @ 3kHz to 5kHz. 

This is the response of full range Telefunken 18cm x 26cm, in the same open back box. No dimple, so it is not caused by the room acoustic nor the box.

Replaced the tweeter of the two way by Telefunken 10cm unit, part number unknown, very similar to the Siemens. Similar dimple as Siemens 28a, while Siemens has better high response.

Characteristic of bare Telefunken tweeter. Dimple exist.

Siemens 28a found on the web. Similar.

Also found some articles saying crossover for 28a should be 5kHz. Sounds reasonable.

Sound-wise, Telefunken full range is better, except two way’s deeper bass.

I will try 5kHz crossover on the two ways ;-)