Electro-voice V1 microphone restoration
- Replace ribbon and rewire.
UPDATE: April 27, 2005 - I've received the 1.8 micron 99% aluminum foil... my goodness this stuff is fragile! I'll let you know how I make out corrugating this material. I think I'll wait until the Lundahl transformers arrive though, slated at about 3 weeks time - just long enough to practice holding my hands still and not breathing... :-)
When I received this microphone after buying it on ebay, it wasn't passing any signal (the seller did advertise that it was a failed attempt to replace the ribbon). What I found was that the ribbon was flat and thinking back, I don't believe it was sandwiched between the isolation material at each end. I removed the ribbon and used it for rough calculation of size.
Following wonderful instructions from another site at http://www.lkmusic.co.nz/ribbonfix.htm, I decided to tackle the job with household aluminum foil as a starting point. After scouring all rooms of my home and the garage, I found a round screw cap from an old Value Village find to use for corregating the ribbon after cutting it to width.
Listen to sample below
Listen to a second audio sample of the V1 microphone here. I replaced the ribbon a second time, this one with wider corrugations based on another round form. A friend was visiting and noticed that the grip on the pop filter looked similar to what I showed him previously, except with fewer corrugations per inch. I'll count them and add that figure to the site notes. I also did the same wiring as the V2, adding a second wire down the other side of the ribbon and joining near the transformer. See photos below.
New Photos Added April 4th
Some of my tools. I found a flat plastic ruler with good edge contact along its entire length, this to use as a guide for the Xacto knife. Using just enough pressure to cut through, with a new Xacto blade, produced the cleanest cut without a burr on the edge of the aluminum foil. Too much pressure caused a burr with a torn look. The pop filter has a knurled outer surface on the connector for the stand. I used this to add the corrugations to the ribbon. This is did by marking off the area I wanted to corrugate and beginning there, gently pressed the ribbon into the connector. While holding it with one hand, I moved forward to the next section with the other hand, careful not to let go of the first until I began the next impression. If you do let go too early, I found that the spacing could be thrown off. The white card is a smooth hard finish that allows for a good cut.
The new ribbon is in place. There are isolators made out of some sort of plactic material, two at the top and two at the bottom, that sandwich the ribbon between them. Because I corrugated around a circular surface, the biggest challenge was handling the ribbon that wanted to curl up. I left enough straight ribbon at each end to be able to control the ribbon during attachment phase. I tightened the bottom first and then gently pulled at the top, through the plastic "clamps" until the ribbon was straight and centered between the magnets, and then tightened the screws on the top clamps. I then folded the ribbon back towards itself and attached the connectors for the wires. These have isolating washers on the back side and the hole is big enough that the screw doesn't touch the metal of the chassis. I think this is necessary, so be careful when tightening the screws for the connectors that the assembly is centered. I did measure with a meter and it appears that a direct connection to chassis is not there. (if someone know's different, please advise).
The wire to the top of the microphone has been reconnected here. Similar to what Dave Royer mentioned in his great comments on Larry Killip's web site describing ribbon replacement. I've run the wire down both sides of the microphone and joined them at the bottom near the transformer input. When I fired the mic up again, I did notice much better rejection of higher frequency buzz than before. With fewer corrugations to the inch, also perhaps a different tension on the ribbon, I found the tone quite different from the first ribbon replacement. I've left the V1 first test and the new second one on this page so you can compare the noise.
I still find the buzzes, etc to be annoying and have requested more information on the Lundahl LL2911 transformer for ribbon microphones. This should give me more gain and a balanced output on the microphones. This, along with a final ribbon replacement using high quality aluminum foil 1.8 microns thick should make these microphones very nice sounding. I'm already quite happy with the V2, although the low frequency buzz is still a problem with it.
The silk "sock" has been put back on at this point. I'm awaiting some new silk material with instructions on how to best fasten it. On the V1 and V2 mics I have, the material is black and sewn at the top to fit around. I have heard that on some microphones the material is fastened to the grill. I may do this when I get the new white material. Logic tells me that this would do a better job of controlling air movement around the microphone.
I may sandblast the brown paint off and repaint before the final assembly. The present finish is chipping off in some places, especially near the switch.
What I notice about the microphone now is far less interference noise in the higher frequencies, but I still have quite a serious ground loop somewhere in the system, partly to do with the microphone. It is very picky on orientation in the room related to the amount of low hum pickup.
The tone is also quite different now than after the first re-ribboning. The previous one was too hard sounding for my ears, but did have quite a nice top end to it in the 5k region. Now the mic has a warmer tone, but may suffer from a low resonance as well. The combination of looser ribbon and few corrugations may be responsible for this. I'll most likely do a couple more re-ribboning jobs on this mic using the household aluminum foil before tackling it with the "real" material (which I haven't got hold of yet).
The Lundahl Transformer arrives!
Yes, I've now installed the Lundahl transformer in both microphones. I have the 99% aluminum foil, approximately 1.8 microns thin, but haven't managed to find the gears yet to do the bends. With the Lundahl transformer installed in the V1 it has improved the sound and level of output, but the old kitchen variety of aluminum foil is just too resonant. I'll do a sample recording in the next couple of weeks and you can hear the outcome of replacing the transformer.
Please feel free to comment on these tests, I'd love to hear from you!
Electro-voice V2 microphone restoration
- Replace ribbon and rewire.
(Photos coming)
The V2 is destined for greatness! :-)
I'm sure that when I have this mic re-ribboned and the balanced transformer in it, it will rank high in my selection of microphones. I already hear hints of wonderful tone for thinner voices, and have tried a bit of a session playing some old rock n roll using it as a room mic - it sounded great, apart from the ground buzz. You must understand, my workshop area is NOT great for wiring, being a converted double-wide and then added onto from there. The power lines are definitely not the cleanest. Then there's my present preamplification - a 1950's Gates "The Yard" mixer that I've basically just got up to limping stage. It still has some grounding problems of it's own, and has had no recapping or circuit checks done beyond shorts and basic voltages (is there power here). Still, this old console has far more gain than my new Edirol FA-101 built-in preamps - I'm also looking forward to it being a great tool in my audio arsenal (see other articles on this site regarding this restoration/frankenstein project).
The rewiring from the top of the ribbon with two wires going around the ribbon did help considerably with higher frequency buzzes and hum, as you can hear in the second half of the audio sample below.
The V2 will stay in its present state with the household aluminum foil ribbon until my supply of "real" aluminum foil and Lundahl transformers arrive. Stay tuned!
I've installed the Lundahl transformer in the V2 as well. While it had better response, the tone was still affected by the kitchen variety aluminum foil.
At this point, I jumped ship and used a complete ribbon and magnet assembly from a Canadian branded ribbon microphone - a real frankenmic; EV V2 body and grill, alternate ribbon/magnet assembly, and a Lundahl transformer. Well, the results are very promising! They're not classic, but I still have the original guts of the V2 and will still replace the ribbon in it sometime in the near future. I'll keep you posted. Watch (or listen) for the new sample of my modified V2 soon.
Listen to an audio sample of the V1 and V2 following ribbon (household aluminum foil) replacement here (note, this is before the transformer replacements).
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