Hello!
Seb : Thank you very much for your nice offer.I have a few Schematics,Documents,and my Studiomate has a also some.Maybee we could put them together and scan them and post them in the Document section.If a few People are interested i realy would like to give something back to this Place were i learned so much.There is a lot of Information and love for the consumer,RFT Consumer hifielectronics out there ,but there is almost no deeper Information about the RFZ professional Stuff in the Net,here and there you find some Schematics but no further Information and i couldn t find a good Collection of audiorelated GDR Equipment.
I think one of the Reasons for the good Sound of these Units is the Quality of the Transformers.I know that the Cmv and UM57 Gefell Tubemic Outputtransformer are of different Quality and can differ a lot,some are good,have good lamination,some just use dynamoiron,due to materialresourceproblems,but that s not true for the RFZ Stuff.I tried to find Information about these Trannys,but if any it is a very flat Info only.I have dissablebed a few of them,to analyse and I am planing to rewire them with a different Ratio for my Micbuilds.Some Mic/small Signaltrannys have a E/I Core made of a high Nickelmetall, most of them have a M core .I found different Metalls for different application.The Au35 Outputtranny has like many others a MU Metallcore,some use a very thin Lamination made from a Metallmix with quiet a lot of aluminium.Some use a kind of M 6\4 Iron,some are black,maybee with a Cobaltcontent.Each winding has a copperfoilshield and some have Airgapps, created with the stacking of the M cores in the same Direction or with Plastikspeacers between the Lamination. Some of Them cary dc where a Gap is needed to avoid Coresaturation, some are Capitorcoupled to block dc, but have a Airgap nevertheless, don t know why . That s why some of them have quiet a lot of windings but a low Impedance,Inductivity. I try to learn more about the Theory of Audiotrannys but it s pretty hard for me because of he Complexity but I don t give up.
Thank You very much.
Lothar