Biula
Well-known member
- Joined
- Mar 24, 2023
- Messages
- 55
I've serviced many original U47 and never had any issues with the NG PSUs. Even the selenium rectifiers seem to work forever.This is an original 1958 Neumann NG47 power supply, unregulated, with original condenser: no issues, dead silent, perfectly working... who said vintage designs cannot withstand modern standards?
They highly over rated, so to speak. The seleniums don't have switching noise and at the low current the resistive voltage drop is negligible. Take the paint off one of the cells and you have a solar cell.I've serviced many original U47 and never had any issues with the NG PSUs. Even the selenium rectifiers seem to work forever.
I disassembled the PSU again and took a picture of the back side of the board.
I think it looks terrible. Even tho I have literally no knowledge about it, I can feel it.. lol Plz look into it.
View attachment 134986
Is it bad??
How could the PSU of 10000 dollars microphone be soldered like this?
for your hard-earnest $10.000 U.S.D. that you spend to buy this hilarious & ridiculous over-priced microphone I wouldn’t accept anything less than a true P-2-P (point to point) construction “from head to toe”, from capsule to P.S.U.
The main advantage to point-to-point constraction is thermal durability over time, moisture resistant & electrically insulating (especially if we are talking about Garolite G-10/FR4 & Garolite G-11/FR5 Glass fabric laminated with an epoxy resin boards), ease of maintenance and modification.So except for being expensive for the sake of being expensive, what's better about point-to-point construction in the dead-simple power supply?
(I'm agreeing about the ridiculousness of the price, but not necessarily the... "motivations"(?)...)
ease of maintenance and modification.
So except for being expensive for the sake of being expensive, what's better about point-to-point construction in the dead-simple power supply?
Tone wise “theoretically”, there's not necessarily any difference.
Practically speaking, however, there's a fairly fundamental difference:
Air has a much lower dielectric constant than epoxy (which is what most PC boards are made out of).
This means even a fairly small gap of air between PTP wires reduces the capacitative coupling to a very low level.
Because as the Rolling Stones sang:But if it's an expensive, "properly" executed and exquisite power supply, why would it need maintenance or modification?
If anyone remembers how the modern “Telefunken” company started and the scam that they were pulling with their $1500 Apex/Nady/etc rebranding…. It shouldn’t be a shock.Easy - cheap(?) labor, or expensive labor performed by people who couldn't give two f**ks about it. That being said, i've seen worse, but I'm confused about the two-layer board being "required" for such a dead-simple design... But I guess they had to make it look "worth the money"..?
I replace the electrolytics with F&T screw caps. I know that components today have better specs but my point is that the NG still work 70 years later. I'm not so sure that the same applies to the Telefunken USA PSU that is discussed in this thread. It's even shipped with a hum.They highly over rated, so to speak. The seleniums don't have switching noise and at the low current the resistive voltage drop is negligible. Take the paint off one of the cells and you have a solar cell.
Even though the long R-C filter is slower than the cut off frequency of the amplification you still have performance that varies with power line voltage, but slowly.
And say what you may about quality of parts, today's electrolytic caps are far superior to those in the 40s - 80s. That PS would benefit with a PP cap as the last one in the R-C string. Solen makes some that are appropriate.
However - get it fixed or preferably replaced under warranty to minimize down time, have your favorite attitude adjuster and be patient.
That was a long time ago, but the memory remains...If anyone remembers how the modern “Telefunken” company started and the scam that they were pulling with their $1500 Apex/Nady/etc rebranding…. It shouldn’t be a shock.
The Telefunken USA microphone does not have a NOS VF-14. It has a grass tube hidden inside a metal case that says VF14k . It has nothing to do with VF-14. They are far from the only one miseading their customers by naming other tubes and solid state replacements after the original part.Air dielectric is superior to anything for high power RF, but for LF dielectric losses are miniscule.
The supply of NOS VF-14 is problematic, Telefunken had quality concerns back 60 years ago getting low noise tubes and switched to JFETs. I do not think the supply of selected low noise VF14s has improved since.
To the OP concern about noise, his mike's tube may need some burn-in, to wake it up, as the tube is run on the cold side. I would leave in on for a few hours before use.
Use it with cable up, to minimize capsule heating.
I have repaired several Telefunken USA U47s, and their power supplies were terrible, including their M251 power supplies. Many of them started to buzz in a very short period of time. The culprit was probably poor circuit design and inferior components. This is similar to The original NG is too different.I replace the electrolytics with F&T screw caps. I know that components today have better specs but my point is that the NG still work 70 years later. I'm not so sure that the same applies to the Telefunken USA PSU that is discussed in this thread. It's even shipped with a hum.
Don't be like that. Not everything Telefunken makes is bad, and expensive. It is just that everything is based on 120 years old heritage, German, American, Irish, who cares as long as it says 120 years old....Telefunken USA, seems like Tele-fakery.
Time to get the funk out of here.
But, not all changes should be considered progress,
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