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Coles 4038 - needs a lot of gain = more noise
Old 4 weeks ago
  #1
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Coles 4038 - needs a lot of gain = more noise

Did some tests comparing a U67 and a 4038 on vocals. The 4038 required about 20db more gain than the 67 to get a similar output. As a result the mic was also noisier...low level hum. I assumed it was noise from preamp gain (BAE 1073)..tried setting both mics at the same dB at the pre and adding those 20db ITB, but the noise was still noticeably greater on the Coles.

Any fixes for this or is it just the nature of the 4038? Assuming in a busy mix it won’t be noticeable, but in a sparse mix on quieter instruments like acoustics and softer vocals, it’s noticeable.
Old 4 weeks ago
  #2
Gear Nut
 

U67 is a condenser; 4038 is a ribbon. Different beasts. 4038 will need something like a Cloudlifter between it and the preamp to provide extra gain, or a preamp with more gain.
Old 4 weeks ago
  #3
It all comes down to the preamp I'm afraid. I got a Crane song spider and it's dead quiet weather I'm using 20db or 60db.

If you feel its causing you problems you can profile the noise and use like waves Z noise to remove it. It can work wonders. Otherwise you can buy a cloudlifter to see if it helps.

Good luck!
Old 4 weeks ago
  #4
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cheu78's Avatar
Quote:
Originally Posted by mikoo69 View Post
Did some tests comparing a U67 and a 4038 on vocals. The 4038 required about 20db more gain than the 67 to get a similar output. As a result the mic was also noisier...low level hum. I assumed it was noise from preamp gain (BAE 1073)..tried setting both mics at the same dB at the pre and adding those 20db ITB, but the noise was still noticeably greater on the Coles.

Any fixes for this or is it just the nature of the 4038? Assuming in a busy mix it won’t be noticeable, but in a sparse mix on quieter instruments like acoustics and softer vocals, it’s noticeable.
Of course the ribbon needs more gain than any condenser out there.

I see two things here:

1. the coles might have some issues (I don't know how bad the "noise" is, although I would not say that the 4038 is a quiet mic, but is not a noisy mic, especially recording vocals or other reasonably loud/close stuff).
2.the preamp might have some issues, that might be more apparent with a coles (since it needs more gain).

In any case with a BAE 1073 or any good quality preamp, you DON'T need any cloudlifter of sorts..

As somebody said, with something like the cranesong (or even the Avedis MA5), I never experience any noticeable/hearable noise.. but it also depends on the source, given that my two points above are not playing a role.

Try with another coles AND another preamp and find out who's the culprit..

I hope this helps,



Cheu
Old 4 weeks ago
  #5
A 1073 (or close clone) would not be a first choice to raise a low level signal, at high gain they are noisy by modern standards. You need a preamp w/ less noise at hi gain. Think Buzz Audio, Crane Song, Millennia, APA, GML, Earthworks, Grace etc. As long as there are no grounding issues (this is often overlooked) where you are tracking then the noise levels should be significantly better than with the 1073 IME.
Old 4 weeks ago
  #6
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nosebleedaudio's Avatar
 

Quickest way to test mic pre; put a 150 Ohm resistor in a XLRM across pin 2 & 3 and crank gain to max..If mic pre is humming there it will be too..
Old 4 weeks ago
  #7
Gear Maniac
 

Just yesterday I pushed the signal of a Coles 4050 (as a very distant piano room mic) with 65db of a more than 50 years old TAB V376 preamp. It not only sounded wonderful, it was also quiet.

So as others said: There might be something wrong with the mic or the preamp.
Old 4 weeks ago
  #8
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I did another test today, and it seems the preamp is fine. Ran it both through my BAE1073, both channels. Same noise level as well as through my Apollo twin - both with a clean preamp and with a 1073 unison plugin.

I think I was just hearing the noise relative to the U67 which is quieter. I did notice that the BAE has a 1200ohm and 300ohm setting and the 1200 is also quieter.

The only other factor I am wondering about is when I did the test for vocals with 67 and Coles, I had them both directly next to each other. Could there be magnetic interference with the two mics in close proximity? Will check for that later.

I think everything is functioning fine and I’ll try the test once more tonight to see if I still perceive an issue
Old 4 weeks ago
  #9
Quote:
Originally Posted by mikoo69 View Post
I did another test today, and it seems the preamp is fine. Ran it both through my BAE1073, both channels. Same noise level as well as through my Apollo twin - both with a clean preamp and with a 1073 unison plugin.

I think I was just hearing the noise relative to the U67 which is quieter. I did notice that the BAE has a 1200ohm and 300ohm setting and the 1200 is also quieter.

The only other factor I am wondering about is when I did the test for vocals with 67 and Coles, I had them both directly next to each other. Could there be magnetic interference with the two mics in close proximity? Will check for that later.

I think everything is functioning fine and I’ll try the test once more tonight to see if I still perceive an issue
Can you bypass the preamp in an Apollo twin? I thought you couldn't but maybe i'm wrong?


I've done tests with an condenser and coles side by side. Never noticed any interference duo to magnetism.
Old 4 weeks ago
  #10
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Bae preamps are going through a burl ADC into optical.
Old 4 weeks ago
  #11
Gear Head
 
Master_Splinter's Avatar
 

This was designed with Coles 4038 in mind.

In fact, it was designed with Coles -

https://www.thermionicculture.com/in...-petrel-detail
Old 4 weeks ago
  #12
Lives for gear
 

While we're on the topic, where on the Coles is the capsule/ribbon? As far as phase aligning with a Condensor, I'm assuming it's in the center of the dimple, and that's what should be aligned with the Capsule of another mic?
Old 4 weeks ago
  #13
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except for some newer ribbon mics with active circuits, all ribbon mics need preamps with lots of clean gain.

i'm mostly using studer d21m preamps and got no reason to use any other unless i want to mess with the impedance; i'm then using grace design m-103's (or amek/neve channel strips for occasional fun).

the cloudlifters just come with me when mixing live and i have to use wimpy preamps...
Old 4 weeks ago
  #14
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chrischoir's Avatar
 

Quote:
Originally Posted by mikoo69 View Post
Did some tests comparing a U67 and a 4038 on vocals. The 4038 required about 20db more gain than the 67 to get a similar output. As a result the mic was also noisier...low level hum. I assumed it was noise from preamp gain (BAE 1073)..tried setting both mics at the same dB at the pre and adding those 20db ITB, but the noise was still noticeably greater on the Coles.

Any fixes for this or is it just the nature of the 4038? Assuming in a busy mix it won’t be noticeable, but in a sparse mix on quieter instruments like acoustics and softer vocals, it’s noticeable.
Typical with Ribbons needing more gain. You need like 80db. I 'm surprised the BAE would be problematic. Usually Neve 1073 sound great with Ribbons. what BAE is it? some of those are not 80db like real Neve preamps. Many BAE designs are hot-rodded 1272 line amps which are inherently only 49db w/ a simple bump up mod
Old 4 weeks ago
  #15
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It’s a BAE 1073MPF. My U67 on vocals sweet spot is at 35 or 40db on the gain. The Coles matches the 67’s output at 55 or 60 respectively...so 20 extra dB
Old 4 weeks ago
  #16
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emrr's Avatar
BAE 1073 versus TAB V376, to quote two examples here. IIRC, the first has not much gain in the input transformer, the other quite a lot. That's the 'free' gain you get before the noisy parts, and why sometimes some really old thing sounds quieter with a ribbon than a modern transformerless pre.
Old 4 weeks ago
  #17
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chrischoir's Avatar
 

Quote:
Originally Posted by mikoo69 View Post
It’s a BAE 1073MPF
yeah that is not a 1073 that is hotrodded 1272. Neve never made a 1073 preamp w/o EQ. The closest thing was the 1290 but it was a slightly different design that 1073 amp section. You can see inside the MPF that is only features a single BA283 card. Neve 1290 specifically features B183 and B189 cards. That would get you the proper gain staging in a single channel unit.
Old 4 weeks ago
  #18
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Preamp isn’t an issue. Actually quieter than the Apollo twin preamp and 1073 emulation. So no excessive noise from the bae
Old 3 weeks ago
  #19
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cerebellum's Avatar
 

Quote:
Preamp isn’t an issue. Actually quieter than the Apollo Twin preamp and 1073 emulation. So no excessive noise from the bae
Good to know as I'm considering a bae as one of my next additions.
From what I have read they can work with ribbons fairly well.

Quote:
The only other factor I am wondering about is when I did the test for vocals with 67 and Coles, I had them both directly next to each other. Could there be magnetic interference with the two mics in close proximity? Will check for that later.
Old 3 weeks ago
  #20
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matucha's Avatar
Maybe try the coles with different cable or move the cable around. It's quite susceptable to pick up EM fields and the higher gain makes it more obvious. I always double check the noise floor when placing using coles. Also I tend to add some highend with EQ if it's obviously needed (often is). That makes potential noise issues more apparent right away and you can solve them before it's too late and then you need to boost some highend .
Old 3 weeks ago
  #21
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cheu78's Avatar
Quote:
Originally Posted by matucha View Post
Maybe try the coles with different cable or move the cable around. It's quite susceptable to pick up EM fields and the higher gain makes it more obvious. I always double check the noise floor when placing using coles. Also I tend to add some highend with EQ if it's obviously needed (often is). That makes potential noise issues more apparent right away and you can solve them before it's too late and then you need to boost some highend .
I do the same, I always push the 28k on the Avedis MA5 to check that.. great combo!
Never had a problem with mine though..



Cheu
Old 3 weeks ago
  #22
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Interesting discovery: “ The 1073 and the 1290 are identical preamps minus the EQ. Inside the 1272 is 2/3 of the 1290 preamp. 1073/1290 has three stages of amplification. The 1272 has only two. BUT>>>>>>> The third stage of the 1290/1073 does not kick in until you hit 55db of gain. So if you use 55db or less of gain, the 1272 and 1073 preamps are identical. Above 55db the freq responce is quite different between the two. The other part is the gain switch. If you add a proper gain switch to the 1272 module it will respond just like a 1073. The original pot only controls one stage at a time. A proper gain switch controls the two stages at one time (and 3 on the 1073 after 55db). I bought a switch from Dave (sound guy) and installed it into my 1272 module. This things is classic NEVE 1073 sound. I have not needed more than about 40-45db of gain from this unit.”

So if I stay at 55dB with the Coles that seems to be the sweet spot (35db with my U67 also seems to be the sweet spot).

Not sure if the part about the gain switch applies to the BAE1073...does anyone know about this?

Anyway, after learning this I plan to use the BAE up to 55dB max, as I’m recording to digital so I don’t necessarily need more output into the converters...and I could always add gain with a compressor after the preamp if I want to hit the converters with more output.
Old 3 weeks ago
  #23
Lives for gear
I have a Coles 4038 - yes it needs a fair bit of gain, but I don't get any hum, I would suggest something else is wrong - either with the mic, your pre or your power supply.
The nearest pre I have to you is my GAP PRE73DLX - not the quietest pre in the world - but it's fine with the 4038, just a bit of hiss which you can't hear in the mix.

Last edited by Scragend; 3 weeks ago at 09:28 PM.. Reason: typo
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