47FET capsule?

[OneRoomStudio]

I currently have a Maiku K47 in my U47 FET mic, and while is sounds pretty good, it's definitely on the dark side of things. I have a Flat K47 capsule in my M49, and have thought about trying that in the 47FET, but I'm worried that I'll run into a similar issue (47FET deemphasis is pretty strong, and a flat or dark capsule is probably going to be too dark).

That makes me wonder, what capsules are folks liking in their FET47's? I wish there was a chart with various capsules on a quadrant, with "treble" (dark to bright) on one axis, and "bass" (bassy to thin) on the other. With these two, I feel like the Maiku would be dark and ever-so-slightly thin, and the Flat K47 would be...well, flat. I think I'm looking for a K47 that is a little brighter, and still has full bass.

 

[Khron]

DOES the U47FET have any "deemphasis" circuitry?

 

[EarthTone]

I have a D7 in my 47Fet’s with the Cinemag remake trafos. Soooo good. I feel like it’s a perfect combo, after trying them on a bunch of different sources. I’m waiting on some Moby trafos too so I will compare to the Cinemag in the 47fet eventually, I also have and like a Heiserman H47fet. The H47fet has Eric’s K47 and the same trafo in it and it is much brighter than the 47’s I built with the D7’s. It is clear and meaty but still pleasant sounding. The D7-equipped 47fets are more middle of the road and chesty and deep sounding. If I had to pick I’d go with the D7 variants.

 

[OneRoomStudio]

DOES the U47FET have any "deemphasis" circuitry?

"deemphasis" is probably a poor word choice. I wasn't talking about U87/U67 style "deemphasis" circuitry, just that with the 47FET circuit, the low-mids push and polar pattern collapsing to super/hyper cardiod in the high frequencies results in a perceived decrease in treble. I'll go with "less emphasis" in the treble

 

[OneRoomStudio]

I have a D7 in my 47Fet’s with the Cinemag remake trafos. Soooo good. I feel like it’s a perfect combo, after trying them on a bunch of different sources. I’m waiting on some Moby trafos too so I will compare to the Cinemag in the 47fet eventually, I also have and like a Heiserman H47fet. The H47fet has Eric’s K47 and the same trafo in it and it is much brighter than the 47’s I built with the D7’s. It is clear and meaty but still pleasant sounding. The D7-equipped 47fets are more middle of the road and chesty and deep sounding. If I had to pick I’d go with the D7 variants.

I wish Heiserman's K47's were still available to DIYers. It sounds like it might be right up my alley.

 

[Khron]

just that with the 47FET circuit,

What's so special about it?

 

[OneRoomStudio]

What's so special about it?

It has an impedance-converter feeding a giant output transformer for one. I'd also guess that C2 and C3 do provide a bit of negative feedback in the traditional "deemphasis" sense of the word:

 

[RuudNL]

I'd also guess that C2 and C3 do provide a bit of negative feedback in the traditional "deemphasis" sense of the word

Negative feedback: yes. De-emphasis: no. It is a 'flat' circuit...
The ratio between C3 (C2) and the microphone capsule capacity determine the gain of the circuit.

 

[OneRoomStudio]

Negative feedback: yes. De-emphasis: no. It is a 'flat' circuit...
The ratio between C3 (C2) and the microphone capsule capacity determine the gain of the circuit.

So if the circuit is flat, what would attribute the sonic difference between this and tube U47 to? I think most would agree that the U47 FET circuit sounds darker and has more low-mids than the U47, which by comparison, sounds more open? The head baskets are fairly similar, so I don't know how much that would impact the sound.

 

[RuudNL]

You can easily test this by injecting a test signal through a 68 pF capacitor and seeing how much the frequency responses differ.

 

[MagnetoSound]

So if the circuit is flat, what would attribute the sonic difference between this and tube U47 to? I think most would agree that the U47 FET circuit sounds darker and has more low-mids than the U47, which by comparison, sounds more open? The head baskets are fairly similar, so I don't know how much that would impact the sound.

The U47 has about 14 more volts on the capsule, for one thing.

 

[OneRoomStudio]

The U47 has about 14 more volts on the capsule, for one thing.

That's a fair point. I wouldn't think 14V would make that big a difference, but it certainly could.

 

[kingkorg]

No, 14v most certainly will not cause any audible effect in this case. It could only if those 14v are on the very edge of what that capsule can tolerate. Let's please put this myth to rest. K47 has a bloody screw right in the middle of it plus the capsule is tensioned with ca.120 grams of weight and then tightened by heating the diaphragm. What is the additional attraction force of +14 volts under those conditions?

 

[kingkorg]

I think most would agree that the U47 FET circuit sounds darker and has more low-mids than the U47, which by comparison, sounds more open?

Do you have any source other than anecdotal backing up the claim that U47 FET circuit, and i repeat *circuit* sounds darker than U47?

 

[OneRoomStudio]

Do you have any source other than anecdotal backing up the claim that U47 FET circuit, and i repeat *circuit* sounds darker than U47?

No proof that it's the specifically circuit, no. But then, as I asked above, what could it be? If it's not polarization voltage, the only other differences are the head basket (minimal), and the output transformer, which also doesn't seem all that different.

I certainly haven't heard every U47 or U47FET out there, but I have heard 2 different vintage U47's and 3 different vintage U47FET's in person, as well as a modern reissue of the U47FET, and a number of clones. At least in my experience, the U47 and the U47FET have sounded quite different, with the FET model sounding darker, but "boomier," and the tube model sounding more "open" and "full." (sorry for the silly descriptive terms, best I can do). I have also seen many people discuss the same opinion.

Are you suggesting that the U47 and the U47FET sound the same?

 

[kingkorg]

Are you suggesting that the U47 and the U47FET sound the same?

No, not by any means, but it has nothing to do with equalization of the circuit. You can not know either that headbasket has minimal impact on the sound. Different iterations of k47 have been discussed to death here, also ageing of the capsules.

Maiku to begin with has very little in common with k47 used either in u47 or FET 47. I have pointed to this before, yet many choose to believe the narative of the "Swiss manufacturer". Neither Swiss, nor manufacturer. Also you failed to mention which capsule is in those u47 mics you compared FET 47 to.

Flat K47 would be...well, flat.

Flat k47 is not flat, there's detailed review of that capsule with frequency response.

I'm looking for a K47 that is a little brighter, and still has full bass.

K47 in FET47 doesn't have full bass. It has slight bass roll off, which doesn't make it too boomy when placed in front of a kick. Exactly why it's used this way.

 

[McIrish]

If the Maiku K47 is anything like their KM84 type capsule, it's super dark in comparison to what it's supposed to be. Their KM84 type capsule sounds nothing like a KM84 at all. The 3U capsule sounded way better and closer to a KM84, but still pretty far from it. Sorry to derail the thread.

 

[OneRoomStudio]

No, not by any means, but it has nothing to do with equalization of the circuit. You can not know either that headbasket has minimal impact on the sound. Different iterations of k47 have been discussed to death here, also ageing of the capsules.

Maiku to begin with has very little in common with k47 used either in u47 or FET 47. I have pointed to this before, yet many choose to believe the narative of the "Swiss manufacturer". Neither Swiss, nor manufacturer. Also you failed to mention which capsule is in those u47 mics you compared FET 47 to.

Flat k47 is not flat, there's detailed review of that capsule with frequency response.

K47 in FET47 doesn't have full bass. It has slight bass roll off, which doesn't make it too boomy when placed in front of a kick. Exactly why it's used this way.

Yes, my point of comparisons were the vintage U47FET’s that I had heard, which is why the Maiku sounds “dark” by comparison and the Flat K47 sounds “flat” by comparison. Obviously, no capsule (outside of measurement mics) sound truly “flat.”

I’m looking for something that has the top end I heard from the vintage U47FETs.

Also, if you say the U47FET circuit is flat, then how does it also have “slight bass roll-off?”

 

[kingkorg]

Also, if you say the U47FET circuit is flat, then how does it also have “slight bass roll-off?”

It doesn't, capsule does.

I’m looking for something that has the top end I heard from the vintage U47FETs.

Kinda difficult to resolve in a forum thread. This can be due to many different reasons, especially if you don't have the vintage mic at your disposal to compare directly and pinpoint the differences. Vintage mics, even Neumann ones have many points where parameters drift over time, especially if they spend multi decade life in front of a kick drum.

just that with the 47FET circuit, the low-mids push and polar pattern collapsing to super/hyper cardiod in the high frequencies results in a perceived decrease in treble.

The circuit has nothing to do with 47FET pattern.

 

[OneRoomStudio]

It doesn't, capsule does.

But that would affect the U47 as well in that case. You said, “K47 in FET47 doesn't have full bass,” but you also said it’s not the circuit, and you also said, “14v most certainly will not cause any audible effect in this case.” This leaves the head basket. Are you saying the FET47 head basket causes low frequency roll off as compared to the U47? Or something else?

The circuit has nothing to do with 47FET pattern.

Agreed. I suppose I could have punctuated that differently, such as, “with the low-mids push in the FET47 circuit, and polar pattern collapsing to super/hyper cardiod in the high frequencies results in a perceived decrease in treble.” As you said, the polar pattern is a result of the capsule, not the circuit (although I do wonder if the lower polarizing voltage has some impact there).

So I am still confused. You seem to agree that the FET47 and U47 sound different, regardless of differences between individual capsules, but you seem to have ruled out all physical differences as the cause for that other than the head basket. Are you saying that is fully responsible for the difference in sound between these two types of microphones?