Real AC701k?

[Somkereki]

I made many custom testers for different mic tubes,they are actually mic circuits terminated with capacitors and the output goes to spectrum /audio analyzers. With this I can get 100% user satisfaction(except the post lose the pack)

Of course, I also measure each electron tube and microphone with an audio analyzer and instruments, print out the results and return them to the owner with a guarantee (before and after). My monitor speakers are Acoustic Research Spirit 142, my headphones are AKG K701. The device for the subjective noise test is a wooden Weimar quartz wall clock, from which I removed the secundum pointer because it was too loud. from a distance of 3 meters. Good luck ! I think it's an art, like making a musical instrument. (The best guitar maker in our country is my good friend, we often ask each other's opinions.)

 

[Somkereki]

I like AC701k better than 6s6b-v and I think it's very impressive that a lot of them are still working perfect.

I do not recommend routinely replacing anything inside a Neumann, AKG or other vintage microphones except electrolytic capacitors. Replacing everything with modern components will alter the sound and decrease the value of the microphone. I service old tube microphones and I rarely need to replace a resistor, except for the really old U47's and other microphones from the 40's and 50's. Cleaning the microphone and servicing the PSU is important. The capsule often needs reskinning and sometimes the microphone calls for a new tube.

I like AC701k better than 6s6b-v and I think it's very impressive that a lot of them are still working perfect.

I do not recommend routinely replacing anything inside a Neumann, AKG or other vintage microphones except electrolytic capacitors. Replacing everything with modern components will alter the sound and decrease the value of the microphone. I service old tube microphones and I rarely need to replace a resistor, except for the really old U47's and other microphones from the 40's and 50's. Cleaning the microphone and servicing the PSU is important. The capsule often needs reskinning and sometimes the microphone calls for a new tube.

I don't replace them out of routine, as you think, but because of the many faulty and "fake" AC 701s, I redesigned the microphone circuits, measured them with an analyzer and listened them to my colleagues. the measured result can often be 20 dB! Because something "factory" can be made even quieter with the right parts and precise work. Measure the value of the resistors, noise, When these microphones were manufactured, there was no such level of noise-free technology. If you digitize the sound, it is even more important in my opinion, and also according to the owners of the studio. But you may have taken better care of these microphones than we did. They are more neglected because of "communism". I talked a lot about this with an old colleague who repaired them at the Film Factory. I think the value of a microphone is determined by its sound quality, not whether it has old noisy components. The capsule and the transformer are the main sound determinants, if I reduce the noise significantly, everyone is happy.

 

[Somkereki]

I don't replace them out of routine, as you think, but because of the many faulty and "fake" AC 701s, I redesigned the microphone circuits, measured them with an analyzer and listened them to my colleagues. the measured result can often be 20 dB! Because something "factory" can be made even quieter with the right parts and precise work. Measure the value of the resistors, noise, When these microphones were manufactured, there was no such level of noise-free technology. If you digitize the sound, it is even more important in my opinion, and also according to the owners of the studio. But you may have taken better care of these microphones than we did. They are more neglected because of "communism". I talked a lot about this with an old colleague who repaired them at the Film Factory. I think the value of a microphone is determined by its sound quality, not whether it has old noisy components. The capsule and the transformer are the main sound determinants, if I reduce the noise significantly, everyone is happy.

 

[tomas.borgstrom]

I don't replace them out of routine, as you think, but because of the many faulty and "fake" AC 701s...

Replacing fake tube and noisy resistors seems lika a good idea. What I mean is that I often find that the noise levels are fine with the original resistors. I record classical music with a pair of M269c. They are in very good shape. The electrolytics are replaced and the capsules are reskinned.

 

[thakava]

I like AC701k better than 6s6b-v and I think it's very impressive that a lot of them are still working perfect.

I do not recommend routinely replacing anything inside a Neumann, AKG or other vintage microphones except electrolytic capacitors. Replacing everything with modern components will alter the sound and decrease the value of the microphone. I service old tube microphones and I rarely need to replace a resistor, except for the really old U47's and other microphones from the 40's and 50's. Cleaning the microphone and servicing the PSU is important. The capsule often needs reskinning and sometimes the microphone calls for a new tube.

I have 2 AC701k I´d like to have tested. Used, but might still test fine... Where in Sweden are you?

 

[tomas.borgstrom]

I have 2 AC701k I´d like to have tested. Used, but might still test fine... Where in Sweden are you?

Malmö, I've PM:ed you

 

[Somkereki]

I have 2 AC701k I´d like to have tested. Used, but might still test fine... Where in Sweden are you?

As I mentioned, I don't change parts out of routine, but after careful selection, measurements and listening to the opinions of several "good-eared" musicians. I also worked as a sound engineer for decades, so I know what it's all about. I also serviced the sound equipment of Hungarian theaters. Also, I successfully use a quantum physics process that makes the sound incredibly detailed. (Studio and home high-end cables, speakers, etc. I am currently repairing a Warm Audio WA-47 microphone, because according to its owner and in my opinion, it is perfectly noisy! For example, 2 x 75 Volt Zener diodes are used for polarization voltage stabilization, which is known to be a noise generator they've been used for a long time. (Below 5 volts the Zener effect dominates, above 5 volts the avalanche effect, which produces a lot of noise). When I'm done with it, I'll upload the measurement results. In many devices, they don't pay attention to the 1/f noise, which is up to 40 It can also cause dB degradation. When digitizing, this causes more bit errors. In analog technology, due to the lower limit frequency of the system, this caused less problems.