We have a small stash of late 1960’s Telefunken AC701 microphone tubes in original boxes. Though these do not have the "K" on them, these are the equivalent to the AC701K. Read more about why below. Sourced from a German tube distributor, these are some of the last un-used, NOS AC701 available anywhere.
Concerned that these are not AC701K versions? Don’t be - since 1965 Telefunken only made frame grid AC701 (same as the "K" version) so there was no need to specially mark them since they were all "K" versions by that time. Also, these tubes have the red indicator mark on them. Telefunken also sold RFT made AC701 under the Telefunken name and those can be rather noisy and more microphonic than the Telefunken ULM made AC701. RFT made AC701 had a white dot versus a red indicator dot applied only by Telefunken ULM.
The date code shows these were made by Telefunken ULM post 1965. In the date code, if you have U for Ulm and then two letters sometimes with two numbers it is made before 1965. If you have a U and seven numbers then it was made by Telefunken ULM after 1965. All of ours have the same date code.
Finally, the last two digits in the date code represent the design revision number, with 03 being the final version for the AC701. All tubes with the 03 revision level match the AC701 ’K’ specs.
This tube is extremely legendary as rare and is used in the most influential tube microphones of all times: Neumann / Telefunken / Schoeps / AKG.
Here is the list of some of the famous mics which uses this tube:
- AKG C60
- Neumann KM50 series
- Neumann KM60 series
- Neumann KM250 series
- Neumann M49
- Neumann M50
- Neumann M249
- Neumann M250
- Neumann M269
- Neumann SM2
- Neumann SM23
- Neumann SM69
- Schoeps M221
- STC 4108 / LYA 28
- Hiller M59 (wiring changes required)
- Hiller M60 (wiring changes required)
- Telefunken ELA M250
- Telefunken ELA M251
- Telefunken ELA M260
- Telefunken ELA M261
12 MONTHS WARRANTEE - TESTED AND WELL PACKED BEFORE SHIPPED
