U67 de-emphasis network

[Paul W]

I don't see a straw man at all... And I don't think the (you) speaking for the (we) thing is valuable at this point. Just speak for your self as I dont think you agree with one another 100% anyway.

I wasn't saying we agree on everything. I was only saying that we agree about the fact that there should be two different mechanisms of low-pass filtering at work: a relatively minor effect of inhibiting the motion of the diaphragm, and the relatively major effect of electrical cancellation.

You straw-manned that position as denying that the diaphragm would move like a speaker at all, and argued against a position none of us held, several times, despite our clarifying repeatedly that yes, we agree that the capsule will act as an inverse transducer to some extent.

That's why I resorted to all caps to get you to stop it. It was getting really tiresome.

for instance do you %100 agree with the statement below.?

I never claimed that we all agree on everything. That was never the point, either, as I think should have been pretty clear from what I actually wrote.

(Kingkorg's response sounds pretty good to me, now that you ask. But that's a different claim than I was defending.)

 

[GeorgeToledo]

You are either not reading what i'm posting, or you have strong convictions that are difficult to change even with posted measurements.

The improvement in THD achieved by using NFB is negligible. Even in extreme conditions it is just 0.5% (@20K) of improvement in u87. And even then THD at LF is dominated by THD caused by the transformer. Even at lower levels. Neumann chose to use NFB instead of simple filter is because why add THD (by using simple filter) when you can reduce THD by using NFB.

To anyone reading this, If you are a kind of person that hears 0,5% THD diference at 20Khz, while at the same time 2nd harmonic rises at those very frequencies, i apploud you. In that case you have to buy the real deal because there's no clone that will ever fulfill all the expectations. That is also if you record at above 130db which is what we are talking about here. And yes, you are probably a bat.

My statement there comes straigt from testing result where i record same exact source with NFB engaged, and disengaged on a u87. I then apply Eq curve that is measured by REW by injecting the signal and exporting that curve into Voxengo Curve EQ on disengaged NFB file. The two files cancel out in null test. I admit i didn't test this with a u67, but i don't see why i would get different result.

 

[kingkorg]

I haven't tested this with wind, nor plosives. I am honestly interested in real world applications, and i have pointed that i have no idea what might happen in extreme conditions. I still don't believe, whatever that article states, the amount of the level in the feedback can counter the plosive coming into the diaphragm.

I managed to put about 22Vpp out of a k67 polarized at 40V. There's not enough juice in NFB to counter that. NFB is not a multi band compressor IMHO.

After all this thug of war thing between us i don’t think anyone is managing to persuade anyone. Maybe we just move on until someone comes up with a legit test to put this to bed.

I see the logic in your proposals, i just can't see it in my tests, and TBH in my world, and how i use mics i don’t care. In best case scenario, and how I view this it could work as low band compressor + what @soliloqueen said happened in her test.

I really don't have anything else to add.

 

[OPR]

My statement there comes straigt from testing result where i record same exact source with NFB engaged, and disengaged on a u87. I then apply Eq curve that is measured by REW by injecting the signal and exporting that curve into Voxengo Curve EQ on disengaged NFB file. The two files cancel out in null test. I admit i didn't test this with a u67, but i don't see why i would get different result.

Interesting that you got full cancellation of the signal recording two separate passes of the same material. I cant even get full cancellation doing that with the same mic let alone one with circuit alteration.
maybe I'm missing something in your method?

 

[kingkorg]

Interesting that you got full cancellation of the signal recording two separate passes of the same material. I cant even get full cancellation doing that with the same mic let alone one with circuit alteration.
maybe I'm missing something in your method?

It's my mic measurement jig i use for measurements. I have to swap between reference and DUT mics and they have to be perfectly aligned for sub 1db measurements.

 

[OPR]

Thanks for posting that George. For some reason I couldn't quote your post. Yes would seem imply a reduction in excessive diaphragm excursions also.

 

[OPR]

It's my mic measurement jig i use for measurements. I have to swap between reference and DUT mics and they have to be perfectly aligned for sub 1db measurements.

Anechoic chamber?
So you're able to record sound picked up by a microphones capsule on two separate passes that null to complete silence? like a digital copy of a wav file?

Was the source file music? a sweep?

 

[soliloqueen]

Changing voltage to the capsule changes the amount of distortion the capsule generates.

As a side note to the discussion of stiffness/tension, in the world of capsules, this is what makes the pvc M7 different from mylar capsules. PVC has self rigidity. I believe the earliest styroflex CK12s (which apparently sucked) would have also had self rigidity, given styroflex that I have encountered.

They do suck. So do tons of early m7s. I was for a while in possession of like m7 number 12 or something. From a collection. That capsule blew chunks. The holes were like 20% too shallow. There was no saving it. Someone here encountered a similar one

 

[tomas.borgstrom]

They do suck. So do tons of early m7s. I was for a while in possession of like m7 number 12 or something. From a collection. That capsule blew chunks. The holes were like 20% too shallow. There was no saving it. Someone here encountered a similar one

I have also had a very early M7 that was very bass shy even after restoration.

By the way. I like U67 an m269 better with S2 lifted. It sounds more choked in the low end with that circuit.

 

[GeorgeToledo]

Thanks for posting that George. For some reason I couldn't quote your post. Yes would seem imply a reduction in excessive diaphragm excursions also.

Oh, this is from Gotham/Neumann’s original catalog literature, by the way.

 

[GeorgeToledo]

They do suck. So do tons of early m7s. I was for a while in possession of like m7 number 12 or something. From a collection. That capsule blew chunks. The holes were like 20% too shallow. There was no saving it. Someone here encountered a similar one

Neumann, the company, was still trying to figure out how to properly implement what was a Braunmuhl-Weber invention and design.

George Neumann had more to do with the early stuff, like the M1 capsule, and I think that one had most prior work already done as well.

It’s a bit of a sidetrack to the topic of this thread, but worth mentioning in that Neumann was much like DIY-ers here.

 

[GeorgeToledo]

Anechoic chamber?
So you're able to record sound picked up by a microphones capsule on two separate passes that null to complete silence? like a digital copy of a wav file?

Was the source file music? a sweep?

I was going to let that one pass because it seemed so dubious, but also, are we talking full null? Or, a 6dB null or something like that.

It is worth remembering that these methods of analysis are crude considering phenomena that happens in actual usage. To fully observe the plosive issue being discussed the diaphragm excursion has to be very close to hitting the backplate if not actually hitting it. Then, does S2 keep the membrane from hitting the backplate and/or reduce the time the diaphragm spends towards the backplate direction before reaching equilibrium.

I don’t think a microphone frequency response test is testing the issue at hand.

ALSO, the testing approach has to be capable of accurately analyzing low frequencies in the first place.

 

[ZHOUJUN]

I have a pair of Neummann PVC M7s and they both have some cracking, reduced output gain, cracking on the back, and I have seen very nice looking PVC M7s but no loss of low end at all.