wiring an old ribbon mic

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simon4

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Hello all
This is my first post on this site but it has been a great source of info to me. I have just acquired an old Cadenza ribbon mic, 50s I think. It seems in good condition and is wired to a quarter inch jack lead. I am getting a sound out when I plug the mic in unfortunately it also seems to pick up radio signals and a lot of hum,which is not ideal! I tried pluggin it straight into my analogue 4 track and it worked but I also have a digital 16 track and am wondering if its OK to use it with that.You can also change it from low to high impedance by wiring it a different way, or so it says in the instructions(the cable has three wires inside).Im not entireley sure what its wired as now but which is better and should I try and change it to an XLR lead? Any help would be welcome.

Thanks
 
I don't know if this will help or not, but kandkaudio.com has a lundahl ribbon microphone transformer that will give you a balanced signal to wire a xlr jack with. The Lundahl transformer is an improvement on many lower end ribbon transformers like my Oktava ML52's. Try at your own risk - though it's pretty much a no brainer installation when you know what to do with the corner posts - read the lastest issue of tape op for a good description. I mention this because you mentioned the buzzing. My guess is this would help. Good luck
 
Simon,

It seems like the output might be wired as an unbalanced, and probably a grounding does not have a good connection.
Yes, you can rewire it as a balanced, and use XLR. It should take care of the problem, if there are no other problems in the mic. First, you need to open it, look at the transformer, and find a secondary winding. Usually ribbon mic transformers are made with 4 or 5 taps. 2 of them would be primary (connected to a ribbon itself). The other 2 or 3 are those you need. If it has 2, connect them to pins 2 and 3 of the XLR, ground pin 1 and connect it to a ground lug of the XLR. Most likely, it should take care of the problem. If the transformer has 3, then one of them will be a center tap, and will be connected to ground. If that's the case, leave it there, but avoid using phantom, if you don't want to blow the ribbon.

The aforementioned Lundahl LL2911 will improve the performance, but first, you have to check if it fits the body.

Caution: Don't use your DMM to check continuity with ribbon connected.
 
still wiring a ribbon mic

Wow thanks for the help guys! I’m a bit baffled by the science as Im not really up on the workings of mics re: transformers and stuff. Interesting that I should be able to rewire to xlr though. I think I should probably do this and see if it works before investing any more money but many thanks for the transformer tip qbert1. ;)
As regards to what you said Marik,the mic has a bit of a funny set up as the wires from the mic and the cable going from it actually connect in the small metal base itself. I’ll try and explain a bit more:

On taking it apart slightly there are three wires coming directly from the mic (head) one black, one green and one red. These go into a black plastic bit which feeds into the base. There are three contact points on the other side of this plastic bit and at the moment I think it is wired to the original coaxial cable. This has three wires one black, one transparent and one copper. The black and transparent ones are wired to two contact points and the copper wire is attached to the small metal stand presumably for earthing. Can I just connect an xlr cable to these contact points and if so any ideas which colour wire from the mic goes to which wire on xlr lead?

Thanks for the help

Simon
 
simon4 said:
The black and transparent ones are wired to two contact points and the copper wire is attached to the small metal stand presumably for earthing. Can I just connect an xlr cable to these contact points and if so any ideas which colour wire from the mic goes to which wire on xlr lead?
Click to expand...

Although these black and transparent wires look like the right ones, I'd track them from the transformer, just to double check, and also, to establish there is no bad connection in the path. It is impossible to say what is their color code. Try to connect them randomly to pins 2 and 3 of XLR. If the mic is out of phase, reverse them.
 
rewiring ribbon mic

Hi Marik ,
Sorry for the delayed response but I have been a bit busy.Thanks again for the advice. I did as you said and took the whole thing apart. As far as I could see the wires connecting to the ribbon/transformer were the three which then came down to the cable. After a couple of tries at wiring the mic to an XLR cable it worked! :D
Unfortunatley there's still a whole bunch of hiss coming through as well as the signal. Am I right in thinking that this is normal for ribbon mics and this is why I need some kind of pre-amp/transformer to boost the signal? It's a shame as the mic sounds great if I could just lose some hiss.

Thanks Simon
 
No, ribbons do not usually hiss a whole lot. However - they don't have a whole lot of output either and to make up for it, you need a great deal of clean gain. I cannot tell you why the hiss occurs exactly since I'm not really that good at electronics, but speaking of ribbons I've got two beyer m260's (they're quite inexpensive) which I'd recommend, should you be unable to fix your present mic.

ragata
 
Hi Ragata
Thanks for the response.The low output could well be the problem as I'm going through a pretty bad mixer and have to crank the gain right up in order to get a signal. I think there may be something wired not quite right either but I'm not too up on the electronics.Thanks for the advice on the other ribbon mics though, it may well be an investment for the future

simon
 
Correct me if I'm wrong here, but couldn't a mic wired with a quarter inch jack also be plugged into a passive DI box to balance it and change the impedance? I could be way off here, but I know its worked for me with the speaker-as-microphone deal.
 
Four years later

Hey Guys,

I realize that this thread has been dead for 4 years, but I just bought one of these ribbon mics off of E-bay and wanted to share my experience for future buyers.:D

First, it should be noted that the transformer does not have a balanced output. It has a common, a Hi Z (80kr) and a lo Z output (30r).

As delivered, the mic picked up a lot of hum and was noisy as well.

Grounding the mic body by connecting a wire from the 3 pin connector to a mounting screw fixed the hum.

With the hum gone, there was still a large amount of hiss when the gain was up. It didn't sound right, so I rewired the mic. The connector is not XLR, so I have included a rough rendering below. (The pin designations are my own and arbitrary). As delivered, the mic was wired with the ground connected to pin 1 and the hot on pin 2. Connecting the hot to pin three quieted the noise floor.
1 o

2 o o 3

My theory is that the output on pin 3 is hotter than pin 2, there fore giving you lower noise.

Regards,

Ray
AVL Solutions
 
New magnets and tranny on the way

I have ordered replacement magnets from K&M magnetics. They are part number BY042. The transformer is the Edcor RMX1. They are back ordered 4 weeks:eek: I am working to improve the sensitivity of the mic. Right now, it is abysmal, and requires amplification that I don't posess. I will post my results when I am finished.

Ray
 
AVL Solutions said:
First, it should be noted that the transformer does not have a balanced output. It has a common, a Hi Z (80kr) and a lo Z output (30r).
Click to expand...

Just unground the common and you have a low impedance balanced output. Well, and ground the shell, but you've already done that.
 
The original poster's question was which impedance should I use? Use Hi-z with a quarter inch jack for most applications. Low-z is balanced and you can wire it with an XLR.

The instruction leaflet tells you exactly how to wire the microphone. Mine is wired unbalanced High z and I have good results from that with a coaxial cable into a 1/4" jack. I had some hum but that was cured by replacing the quarter inch jack. It is also necessary to tighten up the ring collar when using it as the earth goes through that. In this application the ground goes to both the shell and pin 1. The core to pin 3. To avoid having to solder the ground to the case the braid is passed through the screw on the base cover and clamped that way. This produces low output as you'd expect from a ribbon mic but very good quality with domestic recording equipment.

The terminology in the leaflet is a bit dated and the low z wiring mentions using twin feeder cable. This is their old name for balanced. In this application the signal pair are connected to 1 and 2 and the ground braid only goes to the case. You'd use XLR to terminate the other end. I haven't tried this because I don't have any equipment that can use this.
 
Cadenza mic's

Nice work guys.
I have three of these mic's.
All sound a bit different, and the wiring had me really confused to begin with..
At least now they are all working, since I had them re-ribboned by a local guy in Melbourne (Australia) and good to go, though I wish they were easier to mount on a modern mic stand!
 
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