There is a lot of information about what is best for the U47 : old stock uregulated NG PSU or modern, stabilized PSU. However, in different regions of Europe, there are different AC voltages: from 210 to 240 volts. I live in Moscow, and I often have to travel between different studios with my two U47s at work. In different regions of Moscow AC voltage ranges from 210 to 240 V. v Furthermore, the VF14's emission decreases over time and the internal resistance of mic increases . This results in B + voltage drop. Of course, you can constantly adjust the last RC filter in the NG PSU. But you must admit, is quite uncomfortable and unpleasant permanently solder the power supply. With the NG PSU I had a B+ voltage from 100 to 114 volts , depending on AC power. I purchased for these cases the modern PSU from A.Grosser . I found little difference in the sound and tried to understand what it is related to . I asked this question to many experts , but no one was able to answer this question. Finally, I realized what is this difference : the original NG PSU has more internal resistance than the modern, good stabilized PSU. Therefore, U47's dynamic behaves differently with regulated power supply. In general, the difference in sound can be described as : a good regulator improves the best attacks in full frequency range and better transients. Also, you have better overload capacity, impact on low frequencies and less distortion on loud sources. Share your thoughts and ideas about the causes of the difference in the sound. Maybe someone can explain it in another way?
Regulated PSU vs. stock NG PSU for U47
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micaddict
Well-known member
Please forgive. I'm not trying to be a wise guy; just trying to help. I'm not a native English speaker myself, but I think the above sentence, especially without "a" before little, would suggest that the difference is pretty much meaningless. But going by the context of your post, I think (!) you mean there actually is some, noticeable difference. Am I right?
You know, a lot of people make a big deal difference between the power supplies to epic proportions . VIPs like Klaus Heyne or David Bock. When you start to argue with them , they immediately start to gag you and say that the difference is so huge that it is not necessary , and discuss that. However, none of them was able to explain clearly what has caused this difference and why they prefer the old PSU , despite the obvious benefits of a good modern PSU (like A.Grosser's PSU), and about which I have written.
I believe that there is a difference , it audible . But is it significant ? My goal is to find the root of the matter and try to improve the old PSU , while maintaining sound quality, but adding stabilization. I realy love sound of my NG PSU, but I don't want to "repaire" it at every new work place and I want to have stable B+ during aging of my VF14s.
I believe that there is a difference , it audible . But is it significant ? My goal is to find the root of the matter and try to improve the old PSU , while maintaining sound quality, but adding stabilization. I realy love sound of my NG PSU, but I don't want to "repaire" it at every new work place and I want to have stable B+ during aging of my VF14s.
Matador
Well-known member
Such discussions are almost always pointless: people like what they like, and consider different things different.
Two otherwise "identical" PSU's can even sound different: with 20% tolerance for caps one may provide better filtering than the other, or present a lower output impedance to audio than another: both will impact the noise and sound to some degree.
I would suggest trying to add a Zener-based pass-transistor regulator either before or in the middle of the series filter string: this will shield the load (e.g. the tube) from variations in the line voltage, while maintaining the higher output impedance which should give similar sonics as the unregulated PSU. While this would prevent line fluctuations from impacting the voltage seen by the tube, different tubes would need to be tweaked just as before with the older PSU's.
Then you would have the best of both worlds.
Two otherwise "identical" PSU's can even sound different: with 20% tolerance for caps one may provide better filtering than the other, or present a lower output impedance to audio than another: both will impact the noise and sound to some degree.
I would suggest trying to add a Zener-based pass-transistor regulator either before or in the middle of the series filter string: this will shield the load (e.g. the tube) from variations in the line voltage, while maintaining the higher output impedance which should give similar sonics as the unregulated PSU. While this would prevent line fluctuations from impacting the voltage seen by the tube, different tubes would need to be tweaked just as before with the older PSU's.
Then you would have the best of both worlds.
I would like to have the ability to easily adjust the desired voltage with a screwdriver, so I can use one power supply for my two microphones at different lamps. Simple stabilization without the possibility of rapid adjustment is not very interesting, although useful for me.Matador said:
ubxf
Well-known member
could you use a variac so that you could adjust the voltage going in
