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 1 
 on: Yesterday at 11:10:06 AM 
Started by g_dejarnet - Last post by Jim Williams
Any converter with S/PDIF will work with it. For the ADAT lightpipe I/O I use a RME ADI-8-DD digital interface rack, it does all the conversions easily. I bought one used for $500 a few years back.

 2 
 on: Yesterday at 09:46:19 AM 
Started by g_dejarnet - Last post by wildplum
A stereo analog to digital converter with S/PDIF output? ( unless i am misunderstanding you, something like an 8 channel mic pre/converter with adat output would allow you to record 8 more channels via your interface)

 3 
 on: August 09, 2022, 05:56:01 PM 
Started by ilcaccillo - Last post by klaus
We are going around and around on this.
Everyone had a chance to opine, and I am closing this thread.

 4 
 on: August 09, 2022, 05:12:56 PM 
Started by ilcaccillo - Last post by RadarDoug2
Neumann are not dummies. The pad is a tool, put there to use when sources are loud. The signal to noise of the amplifier does not significantly change.

 5 
 on: August 08, 2022, 05:02:56 PM 
Started by ilcaccillo - Last post by Kai
I respectfully disagree: reducing gain at/before the FET gate does not remove any amplifier self-noise past the FET stage. At equal gain settings between padded and unpadded U87, the mic's signal-to-noise ratio is audibly reduced, around 6dB if not more.

Perform the test yourself and listen.
Thatís exactly what I meant:
The -10 dB pad reduces S/N ratio by only about 6 dB for a given SPL, not 10 dB like initially assumed.
This even means the absolute self noise goes down ca. 4 dB and the dynamic range up by the same amount, but only for very loud sources close to 127 dB SPL peak.

The pad is meant to be used with these loud sources, like a closed micíed trumpet, tympani etc. e.g., to avoid internal overload in the mic.
I used a bunch of them on jazz drums with great results (pure luxury), without pad the toms sounded distorted, great with pad.

Unpadded the U 87 can stand just 117 dB SPL, thatís not enough for quite a number of instruments.

Using the pad in a spoken word production e.g., would be a stupidity of course.


BTW:
U 87 can put out 0.39 V only.
If your mic pre can be dialed down to 28 dB gain or lower, U 87 typically canít overload it, assumed it has internal max. voltage of 10 V.

 6 
 on: August 07, 2022, 04:29:13 PM 
Started by ilcaccillo - Last post by David Satz
RadarDoug, the standard definition of signal-to-noise ratio for a studio microphone is based on the voltage that it puts out at an SPL of 1 Pa (about 94 dB SPL). It's not like in consumer audio, where the reference level is the highest voltage that the device can put out. Because of this special definition, signal-to-noise ratios for studio microphones may seem rather low--e.g. only 68 dB for the U 87 A in the cardioid setting, as shown in the attached, abbreviated specification list. But if you add the equivalent noise level to the s/n ratio you get 94 dB, the reference level used for this specification. It's clearly nowhere near the highest SPL that the mike can handle--and that's completely intentional.

If your reference is a fixed SPL, then using the pad on a microphone will detract from its s/n ratio by around the same amount as the attenuation of the pad. Klaus is presumably speaking from that standpoint. You, on the other hand, seem to assume that the reference sound pressure level will be higher when the pad is on--so to your mind, the s/n ratio isn't being reduced by the pad. But according to the standard, the reference level for measuring the s/n ratio is always the same--it's whatever the microphone puts out when a 1 kHz, 94 dB SPL tone is played into it. Throw the pad switch and that signal level goes down 10 dB while the noise floor of the mike stays approximately constant.

Thus the pad is really costing you 10 dB, and shouldn't be used unless it's really needed to prevent the microphone's electronics from being overloaded by the output from its own capsule. If there's no risk of such overload but a "downstream" component such as a mixer input or preamp is threatened with overload from the microphone's output, then a resistive pad should be used at the input of the downstream device; using the pad switch on the microphone in that situation will add 10 dB of unnecessary noise to the channel, whereas a resistive pad will not.

 7 
 on: August 06, 2022, 10:41:53 AM 
Started by ilcaccillo - Last post by gtoledo3
Thanks for your alert observation.
I modified my responses to include the U87, as both models use the same method of gain reduction at the mic amp's input via capacitor between diaphragm and backplate.

Ahh, ok, nice.

One thoughtful reason that people might choose to use the pad in U87 regardless, is that the small output transformer under performs and exhibits non linear overload at high output level. This leads to the results being a bit nasty sounding in some contexts.

This may be the case with U67 as well but I havenít delved into the issue.

 8 
 on: August 06, 2022, 03:34:07 AM 
Started by ilcaccillo - Last post by RadarDoug2
The whole reason for the pad is that you are putting more signal in to the mike. So assuming your signal goes up 10 dB, the output level of the mike will be the same, and the signal to noise will be the same. If you put the same level of signal in to the mike, then you leave the pad out.

 9 
 on: August 05, 2022, 11:33:19 PM 
Started by ilcaccillo - Last post by klaus
Thanks for your alert observation.
I modified my responses to include the U87, as both models use the same method of gain reduction at the mic amp's input via capacitor between diaphragm and backplate.

 10 
 on: August 05, 2022, 09:57:35 PM 
Started by GThomp - Last post by gtoledo3
Absolutely fascinating! Your schematic is dated one day after the first series I have (21.6.1960) which sports the C17.

Your schematic is curiously labeled "U67u", so let me speculate: In addition to the NWDR-rejected model U67 (later re-submitted as M269), Neumann initially contemplated also offering an export/U.S.- version of the U67, without the HF broadcast attenuator ("u" is a Neumann suffix often used for export power supplies, specifically for the North-American market; also note that the U67u schematic is using English language and U.S. component measurements/symbols).

Old topic, but I noticed it because it was linked within the top thread in the forum.

Perhaps the ďUĒ in U67u is for ďUmbauĒ (modification), the same as the rare M49u and M249u.

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