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Neve 1073 N -NO headroom
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Currecubaa
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#1
16th November 2013
Old 16th November 2013
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Neve 1073 N -NO headroom

Hi,

I just bought a Neve 1073 N and I´ve got a(new) Neumann u87ai.

Even when the gain is standing on -20db (lowest) it stills hits distortion level when singing loud. I even use -10db on my u87.

I know Neve is "hot" but can someone tell me whats wrong..?

Thanks, Christoffer
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16th November 2013
Old 16th November 2013
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Most likely, the amplifier on the B283 board hasn't had its bias setting checked since Margaret Thatcher ran Britain... find a tech that has an oscilloscope and check the amplifier bias setting... if that ain't it then its something else.

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16th November 2013
Old 16th November 2013
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Hi
Although the bias setting might be 'out' what are you feeding it into?
The preamp when adjusted manages over +24dBu out and probably not a massive amount less even if not biassed correctly.
Is the power supply actually correct at 24 Volts DC?
Matt S
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16th November 2013
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Are you feeding it in to a -10 unbalanced input?

There is no headroom problem with the stock unit.
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16th November 2013
Old 16th November 2013
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you either feed the mic into the line input (as mentioned above) or maybe your source is too loud for the u87ai? stock u87ais tend to distort easily. but i would assume that you are plugged into the line input by accident.

ps: never use the pad on the u87. it kills the mic entirely.
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16th November 2013
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The 1073N was just released so it should be brand new or pretty damn close to it.
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16th November 2013
Old 16th November 2013
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Perhaps your cable has pin 1 and 2/3 switched and you never noticed before you got a pro preamp?
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16th November 2013
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The 1073(N) has plenty of headroom, the big question here is a) what are you plugging it into, and b) by what method. If you give exact details someone will probably work out what's happening.

To me it sounds like it's being plugged into a mic input on an interface as you haven't given any details to suggest otherwise.
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16th November 2013
Old 16th November 2013
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1073N

If you are going into the microphone preamp with a U87AI and the gain is set to -20db then something is very wrong. The -20db will take the output of my CM47fet LDC microphone 2" out from a kick drum without any clipping.

My guess is you are over driving whatever the Neve 1073 is feeding?

1) Does the U87AI work without clipping distortion if you go into a different preamp... this could anything like a Behringer, Mackie or M-Audio. You are not comparing sound quality but just want assure that the 87AI working correctly and there is not a service problem with the 1073N or the U87.

2) If you plug a SM57, 58 into the Neve does is work in the same audio chain without clipping. I was just recording our CM87 with a Vintage Neve preamp and for vocals we had the input gain set at -40db of gain on an Etta James type vocal. Our CM87 has a nominal output with 3db of a U87AI.

3) Does the Neve 1073N work with any other LDC microphones without clipping distortion or can you measure the phantom supply and make sure there is actually 48v reaching the U87 when it is plugged in?

4) Plug a set of 50 ohm headphones into the line output of the 1073. Now, the output impedance is 75 ohms but this is a NEVE and it should be about drive a 50-600 ohm set of headphones without clipping distortion.

The Neumann U87AI specs are as follows:-

Maximum output voltage 390 mV
Dynamic range of the microphone amplifier (A-weighted) 105 dB
Supply voltage (P48, IEC 61938) 48 V ± 4 V
Current consumption (P48, IEC 61938) 0.8 mA

390mv is an output level of -6dbu before the on-set of distortion.

So, if you set the NEVE for -20 then you have 14db of headroom. However, my guess is the Neve gain should be set to around -40 for the average close vocal which is a level of about .007v.

Now, there is a Hi/Lo switch on the rear of the 1073 that sets the transformer input impedance. It should be set to Hi (1.2K) for a condenser microphones and dynamic microphones. In Low (300 ohms) the transformer will have 6db more gain which is useful for ribbon microphones. However, this shouldn't create clipping distortion just that the gain switch should be set for one position lower for the same output level.

I love solving analogue audio electronics problems as that has been my passion for nearly 45 years now.

So, first determine the U87AI is working correctly into a different preamp and that the Neve doesn't distort with a dynamic microphone.

Cheers, Dave Thomas
aamicrophones.com







Quote:
Originally Posted by londonengineer View Post
The 1073(N) has plenty of headroom, the big question here is a) what are you plugging it into, and b) by what method. If you give exact details someone will probably work out what's happening.

To me it sounds like it's being plugged into a mic input on an interface as you haven't given any details to suggest otherwise.
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17th November 2013
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An excellent set of tests, great post!
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17th November 2013
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i have kind of the same problem. i got a ne neve 1073 dpa yesterday. i am using it on drum overheads with a pair of neumann km184. i have to set to input between 40-50 an the trim pot on zero (far left). even now the clip led are lighting up occasionally when there are some hard hits. if i turn the input or trim just a little bit up, the clip led lits all the time. is that normal?
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17th November 2013
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Hi
So you turn the input gain to 30 or 35dB.
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17th November 2013
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Quote:
Originally Posted by napnap View Post
i have kind of the same problem. i got a ne neve 1073 dpa yesterday. i am using it on drum overheads with a pair of neumann km184. i have to set to input between 40-50 an the trim pot on zero (far left). even now the clip led are lighting up occasionally when there are some hard hits. if i turn the input or trim just a little bit up, the clip led lits all the time. is that normal?
Like Matt said.
Just another thing though, it doesn't always worry me when I see a little clip light winking on an analog piece of gear when on drums. The unit isn't necessarily clipping as the light is triggered 3-4 dB before clipping. Heavy or sustained clip light is probably not a good idea if you are looking for a clean sound but an occasional blink on a heavy hit is just telling you that you're running on the warm side of things.
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17th November 2013
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Your gain staging is wrong on the AMS-NEVE DPA. Turn your trim knob all the way to the RT. That is unity gain on the unit. Then turn the red input gain knob down until the clip light does not light up. Make up gain at the next piece of gear or on your console.
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17th November 2013
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Quote:
Originally Posted by Plush View Post
Your gain staging is wrong on the AMS-NEVE DPA. Turn your trim knob all the way to the RT. That is unity gain on the unit. Then turn the red input gain knob down until the clip light does not light up. Make up gain at the next piece of gear or on your console.
if i turn trim all the way to the right, and the input as low as possible, the red led is lit all the time. is that thing so sensitve? i have no problems with my api 3124 and daking mic pre IV even if its on snare.

i have not tried the neve on a snare so far, but i can not image how to get no clipping when it even clips on the lowest settings on overheads.

maybe some attenuator pads after the mic an before the neve will work?

i usually push my preamps all litte more to get a fatter sound - but with the neve not possible.
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17th November 2013
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Is the sound distorted?
If not, ignore the clip light.

Anyway, methinks something is wrong with your set up. What are your mics? Are they very high output types?
Try padding your mics.
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17th November 2013
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Hi
Minimum gain on these units is 20dB.
Since you can get in excess of +26dBu out of it then the maximum input would be +6dBu.
Can you get this sort of level from a mic? A previous post quotes about -6dBu max from 'your' mic which would leave the Neve with 12dB extra headroom.
Matt S
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17th November 2013
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wow, thanks for all help guys.

the neve guys just checked my pre amp and there`s nothing wrong with it. So its probably something with my U87 ai going into Neve. Does anyone know if bying a pad between u87 and neve a good idea?or does it effect the quality?

thanks, Christoffer
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17th November 2013
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Quote:
Originally Posted by londonengineer View Post
The 1073(N) has plenty of headroom, the big question here is a) what are you plugging it into, and b) by what method.
Quoted again, you're only giving us half the picture. Your U87 is unlikely to be at fault.
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21st November 2013
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it should be low impedance mic mode with a u87. Never had to use a pad on one either.
where is it clipping, the Neve or the ADC?

are you sure you have the output level set correctly?
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#21
26th November 2013
Old 26th November 2013
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U87/1073 clipping

Hi Christopher, Are you using the U87AI for drum overheads????

The U87 has the capsule powered from about 38v dc (48v less the drop across the blocking resistors). The U87AI has 60v on the capsule so not only does the capsule in the AI produce about 4db more output but the upper midrange also increases in level a db or two.

The U87AI has less headroom than a the original U87 and they were headroom challenged. There is definitely a general agreement with seasoned engineers that the U87 does not sound as good with the pad engaged. I have not done any solid testing but I believe this is because of the negative feedback/de-emphasis circuit in the U87 and the pad interact.

Back in the day at Ocean Sound Studios in Vancouver we preferred the AKG 414eb microphones as drum overheads. We had both 87's and 414's.

1) the 414 circuit has 14db more headroom than the U87 and it has a -10/-20db pad that does not seem to degrade the sound like the U87.

2) the 414eb microphones also has less rise in the upper midrange and the low end was tighter sounding. Usually the 414eb has the -10db pad on and at Ocean we had 16' ceiling so we could get a bit of height above the drums.

The maximum output of a U87 before clipping is .39 of a volt RMS (directly from the Neumann specifications). .39 volts is -6dbu.


In my view as a microphone designer this is not enough headroom to use the microphone for drum miking...especially if your room has 8-10' ceilings. Unless its a light Jazz session or folk/rock.

When we built our LDC microphones we used the more elegant 414eb circuit which only cost us $10 more in parts but increases the headroom by 14db.

Drums have a very fast transient attack and the U87 would sound even nastier if it did not have its class "A" transformer coupled circuit. The U87 was designed for spot miking Orchestras and was never designed to be use for close vocals or close drum miking. Now, back in 1968 when the U87 first came out it was only $400 and some change. Large studios of the day bought 10 at a time and they eventually got into the hands of "rock" engineers.

In a big studio with an older U87 then it is possible to use the 87 for drum overheads but you certainly can't get them in as close as a 414eb. However, often drums were dampened more in the 70's and 80's than today. Today's modern snare drums also produce more output level. I use an old 1953 wooden snare as its not as loud as the new metal snares so I can hit the drum a bit harder without it producing a painful drum level.

You would definitely have to Pad the U87AI if you were using it in close for a John Glynn's set-up. You can buy some in-line pads between the microphone and the preamp but if the U87 is being driven into distortion the in-line pad will not help the situation.

When we designed our CM67se which is often used for drum overheads and in front of guitar/bass amps we designed a circuit that can produce 21db more headroom than a U87AI before the pad on the CM67se is engaged.

Nir Z who played drums with Genesis and on the first John Mayer CD uses our CM67se mics for drum overheads they are less than 1/3 the cost of the U87.

I have 9' ceilings in my home studio and with the CM67se set in a John Glynn configuration we usually have the -10db pad in and the Neve 1073 set to -20db of gain. The original API 312 has a 20db pad which need to be engaged when you were close miking drums.

Cheers, Dave Thomas
aamicrophones.com



Quote:
Originally Posted by Currecubaa View Post
wow, thanks for all help guys.

the neve guys just checked my pre amp and there`s nothing wrong with it. So its probably something with my U87 ai going into Neve. Does anyone know if bying a pad between u87 and neve a good idea?or does it effect the quality?

thanks, Christoffer
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#22
26th November 2013
Old 26th November 2013
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Hi
From Dave's excellent piece you should not really NEED a pad as the primary limitation is the mic, however if you do want to try padding then the pad needs to present the CORRECT IMPEDANCE for both the mic and preamp. I don't know what the typical input impedance of the Neve is, possibly 1500 Ohms or thereabouts and it NOT 600 Ohms which would be typical of an old school line attenuator or 10K which might correctly be used for a 'modern' line level application.
Using an impedance lower than the Neve's usual will alter the sound.
These aspects are rarely aired on here and are CRUCIAL for proper performance.
Matt S
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27th November 2013
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the neve should be selectible input impedence if it is a real one. If my memory serves me right, low Z select should be around 250 ohms and hi-z is 1200 ohms.
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