I posted recently about some Klangfilm 70503 tubes I purchased, they arrived, thought I'd show them off once more where all the tubes junkies hang out
These are a very linear 4V 1A IDHT, used in German radios and audio amplifiers from the 1930s, a variant of the Telefunken REN904, very well may have been manufactured by Telefunken, but I cannot say for sure. What I can say is they are excellent sounding drivers, huge staging, airiness and detail in spades, deep impactful bass, very similar character to other REN904 I own but not altogether identical soundwise, so perhaps there are internal construction differences. The tubes from this family had an exterior metallized coating for shielding. It is difficult to find NOS examples with the coating intact (it is more often flaking off or very oxidized), I was very happy to find these tubes, especially in such good condition with original boxes!
Here it is in a lineup with other REN904 in my collection, left to right in my best estimate of chronological order of manufacture. Later models of the REN904 were changed to a 0.65A heater. I recently added a voltage regulators to my amp such that I can use all types
These are a very linear 4V 1A IDHT, used in German radios and audio amplifiers from the 1930s, a variant of the Telefunken REN904, very well may have been manufactured by Telefunken, but I cannot say for sure. What I can say is they are excellent sounding drivers, huge staging, airiness and detail in spades, deep impactful bass, very similar character to other REN904 I own but not altogether identical soundwise, so perhaps there are internal construction differences. The tubes from this family had an exterior metallized coating for shielding. It is difficult to find NOS examples with the coating intact (it is more often flaking off or very oxidized), I was very happy to find these tubes, especially in such good condition with original boxes!
Here it is in a lineup with other REN904 in my collection, left to right in my best estimate of chronological order of manufacture. Later models of the REN904 were changed to a 0.65A heater. I recently added a voltage regulators to my amp such that I can use all types
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