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Ribbon Microphones help needed




 
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W2PFY
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« on: March 07, 2017, 05:47:33 PM »

I just purchased a ribbon microphone MXL R144 Small Ribbon Microphone from a music supply house. It is by no means an expensive microphone. ($99.00)

I have no experience with any ribbon microphones, but what do I need to know? I understand that it needs to look at 1500 ohms. Will I need an outboard transformer to match this up to the input on my Behringer mic amp? It looks like it does not need a fantom B+ supply. What would happen if you accidentally socked the power to it? Maybe a schematic is out there but I thought I would post it here for some experts on the subject to educate me.

For what it is worth, this is a very popular microphone that can be modified for about 300 bucks and the result is reportedly, to sound better than a $1000.00 ribbon microphone?

Thanks in advance..Terry  
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« Reply #1 on: March 07, 2017, 06:17:57 PM »

Terry,

First off check this out:

http://recordinghacks.com/2008/11/01/chinese-ribbon-microphone-designs/

All the Chinese imported ribbons have the same guts ( 3 types) and are repackaged by various manufacturers. Your Behringer "Mic amp" (not sure which one) typically has a 3K input impedance, and will absolutely have enough gain for the MXL ribbon. It does NOT require phantom power, and most manufacturers recommend you turn it off.

What you will discover is a LOT of low to mid bass response and probably will require a little EQ jiggering and a boost in the presence rise area.. There is a smooth quality to ribbons in general.. I'm sure you'll have fun experimenting..

Not sure what $300.00 service you were referring to, but "re-tensioning" the ribbon seems to be a popular service. I don't think you'll need any of that!

Jeff
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« Reply #2 on: March 07, 2017, 06:52:26 PM »

I have the MXL R144 Heritage Edition mic (same as yours, just a different color).  Have been using it on AM and enjoy its very smooth sound.  A couple things, however.  Its output is low and you'll have to crank up the mic gain.  And the highs roll off and so you'll probably want to boost them with a suitable EQ.  I run mine into a Symetrix 528E and have the lows (~100 Hz) cut about -3dB and the highs (~5kHz) boosted about +9dB.  Obviously you'll want to play around with the EQ...

Its ribbon length is 47mm so it presumably fits the "Medium Length/Long Path" category in the above article.

Any load impedance above 1500 ohms is fine.  And as has been pointed out, turn off the phantom supply.

Good Luck.



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« Reply #3 on: March 08, 2017, 06:23:31 AM »

I believe the $300 upgrade is to replace the mic's cheap output transformer and re-tension the ribbon.

Frank WO4K
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« Reply #4 on: March 08, 2017, 08:34:41 AM »

I also have one and concur with all of the above. I was told, never confirmed, that the phantom voltage can damage it. I also did find a small piece of paper packaged with the mic that said the same thing. EQ'ing is a must - virtually no highs. It got better by cutting the lows rather than just boosting the highs.

One other thing, you will need a good wind screen - it's very sensitive to any air that hits it.
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« Reply #5 on: March 08, 2017, 11:13:24 AM »

The re-tensioning thing likely goes back to the original ribbon mics which were known to suffer from ribbon sag. All the ribbons I've seen were corrugated like a cardboard box. Over time poor storage, improper use, or just overall age would cause the corrugations to flatten out somewhat causing the ribbon to go slack which made the mic sound crappy.

No idea how the new China mics are made, but with the old RCA 44s, 77s and the like, storing them on their side was recommended. And Terry, you probably already know this but just in case - don't blow into the mic to test it or otherwise. You can stretch or break the ribbon. I wouldn't think a brand new mic should need any ribbon work, but who knows? Maybe it's a QC issue. Or a justification for the $300 charge.

As has been said, they all sound muddy and require some equalization to flatten things out. I run a little JoeMeek EQ/compressor on my 77D, nothing else. Find someone you know and trust with a good ear who can hear your signal well, get it set, and resist the urge to twiddle. Playback comes in handy here, provided both stations can handle the full fidelity.
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« Reply #6 on: March 09, 2017, 10:28:11 PM »

Captionmarvelous,

Buy one of those round embroidery hoops from a crafts store or Wallyworld, and get some panty hose.
Put the panty hose in the hoops, and rig up something to hold it in front of your mic = pop screen.
They sell them commercially, but this is cheaper and faster assuming you can hold it in front of
the mic...

Also these mics have "proximity effect" you get ur "BAs" blown up big as you get closer in to that mic.
So, back off a few inches and the bass won't boost as much... of course EQ - especially low CUT
is not a bad idea either...

              _-_-
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« Reply #7 on: March 09, 2017, 11:17:02 PM »

Captionmarvelous,

Buy one of those round embroidery hoops from a crafts store or Wallyworld, and get some panty hose.
Put the panty hose in the hoops, and rig up something to hold it in front of your mic = pop screen.
They sell them commercially, but this is cheaper and faster assuming you can hold it in front of
the mic...

Also these mics have "proximity effect" you get ur "BAs" blown up big as you get closer in to that mic.
So, back off a few inches and the bass won't boost as much... of course EQ - especially low CUT
is not a bad idea either...

              _-_-
I made one exactly as shown here. Hopefully your wife or XYL has some black panty hose to donate -- it's the most expensive part of the project.
73, Jim
https://www.youtube.com/watch?v=WcB3s8KOk4w
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« Reply #8 on: March 11, 2017, 07:43:36 PM »

Thanks for all the tips guys! I learned a lot and I also looked at some A,B & C comparisons on YouTube where most were comparing the sounds reproduced by much more expensive microphones mostly with acoustic guitars and the results without Re-EQing, were outstanding considering the price. I decided not to keep this microphone and order one just slightly more expensive by the same manufacturer that does indeed need the 48 volt phantom power. This will prevent me from blowing the mic after a few good Guinness Draught beers! I prefer Lowenbrau from Germany (not Switzerland) but they don't sell it around here Cry Cry   Now on a hungover Sunday morning I may have the lowest voice in America Grin Grin Grin Maybe the long lost Jay will tune in for a comparison? N3WWL that is!
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« Reply #9 on: March 11, 2017, 07:48:20 PM »

The re-tensioning thing likely goes back to the original ribbon mics which were known to suffer from ribbon sag. All the ribbons I've seen were corrugated like a cardboard box. Over time poor storage, improper use, or just overall age would cause the corrugations to flatten out somewhat causing the ribbon to go slack which made the mic sound crappy.

Au contraire, mom ami...

Both RCA and Wes Dooley (rebuilder of RCA ribbon mics) said ribbon vertical storage is correct.

73DG
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« Reply #10 on: March 11, 2017, 08:05:31 PM »

Good tip Dennis ! Looks like I can't leave well enough alone with my condenser mics?


BTW, that guy in Maine has lost the schematic for that 3 phase xformer and he doesn't have any left...
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« Reply #11 on: March 11, 2017, 08:09:49 PM »

Condenser mics are not sensitive to storage orientation.

No sweat on the iron, I found the manufacturer.

73DG
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« Reply #12 on: March 12, 2017, 12:21:23 PM »


Both RCA and Wes Dooley (rebuilder of RCA ribbon mics) said ribbon vertical storage is correct.


Yep, absolutely true, D. Especially since the mics are used vertically. Always best if you can store them that way, too. Problem is that many of the mics (77, 44, etc) are top heavy, so stations and studios would lay them down when boxed. Been years but I think it was Clarence Kane who said store them on their sides if you lay them down. He started with RCA right after WWII and I thought he was retired, but someone told me recently he was still in business.

I found this one one of the audio sites, from a fellow who needed to get a new ribbon in a 77C-1:


Quote: Originally Posted by Joe **** View Post
Don't you have a great story for us, as to WHY it needs work? Did'ya slam a door next to it or something??

My girlfriend tapped it a couple of times in the studio, then she blew into it, like she was trying to blow out candles on a birthday cake, and asked, "Is this thing on?" The answer was, "Not anymore."

That about sums it up! 
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« Reply #13 on: March 13, 2017, 06:44:17 PM »

Here is a link to a site that walks through a transformer upgrade:
http://www.preservationsound.com/?p=3687

Here is a link that offers upgrade mods for inexpensive ribbon mics:
http://www.oktavamodshop.com/index.php?cPath=1_24&osCsid=a6baec5c932f8362167ffe7aecc56ea5

Frank WO4K
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« Reply #14 on: March 13, 2017, 07:32:03 PM »

 Maybe some of you are familiar with the Timmy (WA1HLR) A/B antenna tests.. Tim always has a switch and an alternate antenna handy! He also has a bevy of microphones on hand, including an RCA 44 ribbon. He is well aware that MY favorite microphone for his distinctive voice is : you guessed it, the RCA. And true to form, Tim "A/B's" the RCA by turning it around and demonstrating the "A phase, B phase", that the bi-directional (figure eight pattern) of all ribbon mics have. His voice sounds melodious and smooth on that mic!

1. Things worth noting: Most incarnations of ribbon mics are susceptible to induced hum from nearby electrical fields..

2. Because their pattern is figure 8 (bi- directional, front and back), any noise in front of you (buzzing transformers, etc.) will be picked up quite well!

3. The natural frequency resonance peaks in the low-mid area commonly known as "the mud frequencies". EQ is essential!


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« Reply #15 on: March 13, 2017, 07:35:35 PM »

And ladies in the broadcast studios didn't like the RCA 77's, said "it puts hair on your chest". Cheesy

But the 77 was the best brass mic in the music biz forever.

73DG
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« Reply #16 on: March 14, 2017, 12:34:32 PM »

In other words, rather poorly suited for amateur radio use.  Grin



1. Things worth noting: Most incarnations of ribbon mics are susceptible to induced hum from nearby electrical fields..

2. Because their pattern is figure 8 (bi- directional, front and back), any noise in front of you (buzzing transformers, etc.) will be picked up quite well!

3. The natural frequency resonance peaks in the low-mid area commonly known as "the mud frequencies". EQ is essential!

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« Reply #17 on: March 14, 2017, 12:48:32 PM »

In other words, rather poorly suited for amateur radio use.  Grin

So are a lot of ops I hear, too....

73DG
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« Reply #18 on: March 14, 2017, 05:29:25 PM »

Terry,

Why does/would a ribbon mic require or use phantom power?

The only thing I could think of is an active preamp in the mic??

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« Reply #19 on: March 14, 2017, 05:57:33 PM »

Well Bear, it doesn't require the phantom for the plain R-144 but the Heritage model does. I am going with the Heritage model so that I won't make the mistake of applying that voltage to the microphone. I understand that if you are using a balanced line, the risk of damage is not there with the plain MXL, however from what I have read, if you go unbalance, you could damage the microphone. So for 10 dollars more I can get the Heritage model that requires 48 volts.

BTW, the ad does not say that there is a preamp in there so I'll research it further.
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« Reply #20 on: March 14, 2017, 07:18:45 PM »

According the the R-144 HE manual, it does not require any power. The manual explicitly states NOT to apply power.

http://www.mxlmics.com/manuals/studio/R144-HE.pdf
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« Reply #21 on: March 14, 2017, 08:32:48 PM »

I guess the people at these different music sales sites don't know what the hell they are talking about? I looked a about three dozen sites on Google and they all warn you about applying voltage to the microphone. I have the Non Heritage model here and I am really glad that I asked questions here before hooking it up! The troubling part about all this is half of the music supply houses list the Heritage model as needing the phantom power?

I wonder how many returns they get s a result of this poor advertising?

On my instruction sheet, it clearly indicates that no supply is needed and that damage will occur if used? So I guess there is really no reason to spend more money on the next so called better microphone?
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« Reply #22 on: March 15, 2017, 03:00:59 PM »

Here is a few ways to take the confusion out of this Phantom Power.

Phantom power is power supplied to a microphone with active devices in them like condenser microphones. power is sometimes duplexed to the mic from a supply in the audio line. After powering the mic's active device the Phantom Power is filtered off (in the supply box) and only audio goes on to whatever you want.

I ribbon mic has no active devices in them. The ribbon mic is a power generator. A very small fragile generator at that. A strong permanent magnetic field closely surrounding a non magnetic ribbon. When the ribbon vibrates in the magnetic field, a very small amount of energy is developed and translated into audio.
The ribbon is made of ultra thin aluminum foil. It is not magnetic but fragile.

If you duplex Phantom Power to a ribbon mic you send electricity to the ribbon. For a foment the ribbon will glow red hot and fall in ashes to the bottom. Poof!    That's a bit dramatic but you get the idea.This is my understanding and, like always, if you have a better information let me know.

Mike 



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« Reply #23 on: March 15, 2017, 03:57:22 PM »

There seems to be a lot of confusion regarding ribbon mics and phantom supply voltages.  Virtually all commercial preamps and mixers apply the phantom voltage to both pins 2 and 3 as shown in the attached Symetrix 528E schematic.  Condenser mics that require this voltage power their internal active amps by connecting to either (or both) pins 2 and 3 for Vcc and pin 1 for ground.  To my knowledge all ribbon mics have built-in step-up transformers as shown in the attached schematic from one of the above sources.  Note that if phantom voltage were fed to the ribbon mic, all that would happen is that the transformer secondary would be elevated above ground, but that no voltage would be directly fed to the ribbon.  Therefore there should never be any real danger if phantom is accidentally fed to a ribbon mic.


* 528E.JPG (69.6 KB, 857x555 - viewed 43 times.)

* MXL-R40-Schematic.jpg (137.97 KB, 643x1024 - viewed 38 times.)
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« Reply #24 on: March 16, 2017, 08:34:27 AM »

So the obvious question, why than are there warning about the possibility of doing serious damage? Not doubting you, just wondering.
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