Marantz 7T Preamp Transistors

mtflycaster · 18th December 2007, 06:54 AM

All seem to be labeled with Marantz part numbers, rather than actual transistor designations. Has anyone out there decoded these and ID'd one or more substitutions?

F34 1019
F34 1020
F34 1021
F34 1022
F34 1023
FDTM1A
FDTM2
FDTM3

Thanks in advance!

MTfly

mtflycaster · 29th December 2007, 02:38 PM

Anyone?

OK. Well, I've kinda figured out that there are likely many possible transistor substitutes based on the requirements of the circuit design and operating parameters.

Just gotta figure out what those are!

Don S · 29th December 2007, 07:07 PM

Transistor substitutions may be hard to come by. I believe that the 7T used germainium transistors. They have a much lower Vbe than silicon, which would require a complete rework of the circuit values. Someone please correct me if I am wrong.

Don S

john curl · 30th December 2007, 01:54 AM

They should be silicon transistors.

mtflycaster · 30th December 2007, 04:34 PM

Hi John and Don -

I think silicon, also. They don't have metal or "black glass" cases. I think made by Fairchild in mid 60's. Look like brown plastic.

Here is a picture....

Regards,

Pete

18th December 2007, 06:54 AM	#1
mtflycaster diyAudio Member Join Date: Nov 2007	Marantz 7T Preamp Transistors All seem to be labeled with Marantz part numbers, rather than actual transistor designations. Has anyone out there decoded these and ID'd one or more substitutions? F34 1019 F34 1020 F34 1021 F34 1022 F34 1023 FDTM1A FDTM2 FDTM3 Thanks in advance! MTfly

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29th December 2007, 02:38 PM	#2
mtflycaster diyAudio Member Join Date: Nov 2007	Anyone? OK. Well, I've kinda figured out that there are likely many possible transistor substitutes based on the requirements of the circuit design and operating parameters. Just gotta figure out what those are!

29th December 2007, 07:07 PM	#3
Don S diyAudio Member Join Date: Nov 2006	Transistor substitutions may be hard to come by. I believe that the 7T used germainium transistors. They have a much lower Vbe than silicon, which would require a complete rework of the circuit values. Someone please correct me if I am wrong. Don S

30th December 2007, 01:54 AM	#4
john curl diyAudio Member Join Date: Jul 2003 Location: berkeley ca	They should be silicon transistors.

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