TC: DIY Project with parts from Siemens Klangfilm units

RIAA preamps with Siemens Parts

		According to the RIAA equalization curve many hifi designers quote that the bass reponse must be increased about 20dB at 20Hz and the high frequencies must be decreased about 20dB at 20kHz. From the sonical point of view it is much more important that the RIAA equalization is correct at 100Hz and 10kHz where about 13.6dB of increase / decrease are necessary. This way I give values for these two test points. Personally I prefer accepting a 1-2dB nonlinearity in RIAA response before adding more parts or tube stages for equalization (which easily can lead to worse phase response…)

	Base		Tubes (per Channel)	Amplification Equalization	Schematic	Comment
	Klangfilm KLV-002 KLV-004 KLV-009		EF804s EF40 ECC83	CLICK HERE!!!		Watch the special site for RIAA preamps with these amps... CLICK HERE!!!
	Siemens Haufe T-41		1 EF86 in triode mode (or EF40, EF804s)	About 33dB 100Hz: +15dB 10kHz: -13dB		Good sound with sensitive preamps. Slightly increased bass response.
	Siemens Haufe T-41		1 EF86 in triode mode (or EF40, EF804s)	About 38dB 100Hz: +14dB 10kHz: -12dB		Good sound with sensitive preamps. Recommended when cartridge lacks some highs.
	Siemens Haufe T-41		1 EF86 in pent. mode (or EF40, EF804s)	44dB 100Hz: +14dB 10kHz: -15dB		Nice working with standard line pre amps.
	Siemens Haufe T-41 (mod for 6SELA2154)		1 EF86 in triode mode (or EF40, EF804s)	About 38dB 100Hz: +14dB 10kHz: -12dB		Great solution for Siemens 6SELA preamps. Fantastic sound. Click here for my 6SELA2154 modification.
	Siemens 6SELA 2524, 2525, 2600, 2525d		3 ECC83 2 EF40	CLICK HERE!!!		Schematic for MM and MC. Use the EF40 tubes or the T-41 input transformers for MC. Great performance.
	Beyer 35806		½ E88CC (one ECC88 for stereo)	32dB 100Hz: +?dB 10kHz: -?dB		Good sound with sensitive preamps.

	Building up a RIAA preamp you can choose between active or passive equalization (or a combined design). I will not start discussions about what is better, but active equalizations can be very simple when having a constant input load. And here is the problem. Different MM phono cartridges have different impedances and will vary the input load. This problem is solved using an MC cartridge with an input transformer which offers an almost constant impedance curve to the following stage. So be careful: Many of the schematics above will only work fine with the requested transformers. Furthermore nonlinearities of the input transformers frequency response may also be compensated by the following RIAA equalization.