Converting Old Shure unbalanced Mic to balanced XLR

[Colonel Monk]

Howdy:

A bandmate just came up with a few old Shure Unidyne B dynamic mics. Model Number PE515.

They seem to be built fairly well, and we tested one of them out at a rehearsal and though it is an unbalanced 1/4", it seemed like it was plenty hot into the mackie mixer at one of our rehearsal spaces.

I read about them a little online, they were a kind of limited range mic used for vocals, guitar, etc..

The 1/4" cable is hardwired to the mic.

What I'd like to know is whether or not I could convert these two mics to balanced XLR?

Though they seem hot enough, The cables aren't very long and I worry about noise.

At this point, I'd say their main use would be to cover vocals at our guitar player's house. We don't record there. Drummer and I are in another project together and I really don't like hauling my gear around unless it's necessary, so we have good mics we just would prefer to leave them at the studio.

I'm pretty competent with a soldering iron, I just fixed another broken mic today and made a few cables. Just not sure if there's anything happening with the conversion to XLR other than adding a shield to the cable.

Regards,

Col Monk

[Bill@WelcomeHome]

If you open the Shures at the cable entrance you'll find that the transformer has multiple wires. Shure has data sheets, no doubt, to tell you which wires to use for a balanced connection.

[Colonel Monk]

Originally Posted by Bill@WelcomeHome

If you open the Shures at the cable entrance you'll find that the transformer has multiple wires. Shure has data sheets, no doubt, to tell you which wires to use for a balanced connection.

Thanks. I wasn't sure if it even had a transformer in it, but it might.

Though I haven't yet found the data sheet for this exact model, suprisingly they do have them for similar ancient models and so I might just be able to get that info.

This Mic, having no XLR, has a spanner nut at the bottom retaining the strain relief. Hopefully the transformer is on the other side, as I have removed the cartridge from the top already and the switch is there but transformer is not just under the cartridge as I'm used to.

Thanks

[TRA]

The PE515 is a hi-z mic. There is nothing you can do by accessing the transformer because there isn't a low-z winding or any additional taps. Your only option is to pick up a Shure A95U which is a matching transformer that will go inline.

Check out pages 4 and 7:

******//es.shure.com/idc/groups/publi...o_pe515_ug.pdf

[ears2thesky]

You could simply run it into a DI box as you would with a synth or acoustic guitar. There are many inexpensive options to choose from.

That being said, it might be a better idea to just get a SM57 or SM58 and lose the relic.

[Colonel Monk]

Originally Posted by TRA

The PE515 is a hi-z mic. There is nothing you can do by accessing the transformer because there isn't a low-z winding or any additional taps. Your only option is to pick up a Shure A95U which is a matching transformer that will go inline.

Check out pages 4 and 7:

******//es.shure.com/idc/groups/publi...o_pe515_ug.pdf

Thanks! you found it!

I still have a bit to learn on fundamentals hi vs lo Z... I know which works better and repairing them is easy, but I don't have a firm grasp on the hows and whys.

I'll look into some inline transformers and see what happens...

[Colonel Monk]

Originally Posted by ears2thesky

You could simply run it into a DI box as you would with a synth or acoustic guitar. There are many inexpensive options to choose from.

That being said, it might be a better idea to just get a SM57 or SM58 and lose the relic.

I totally hear you. I actually have other mics, including those you mentioned. I use an SM 58 for my vox, like most of the rest of the world. One of these relics I was going to use for the one song I sing for rehearsals at guitar players house, my drummer would use the other one and he has no cash for new equipment....

It actually sounds fine for live vox, and is plenty hot - but I've heard so many bad 1/4 mics I was just thinking if it could be converted we'd be better off.

Turns out, that some of the other Shure 515 Mics do have a transformer, but this one doesn't. No biggie.

Better studio mics for our good rehearsal studio on the next thing on the menu. We've just upgraded our DAW and recording mixer, so over the coming months we will be hanging onto our regular Shure mics for live stuff and replace some of them with better quality studio-fare.

Thanks for the help everyone.

[Sim]

Originally Posted by ears2thesky

You could simply run it into a DI box as you would with a synth or acoustic guitar. There are many inexpensive options to choose from.

That being said, it might be a better idea to just get a SM57 or SM58 and lose the relic.

What are you crazy from my experience shure's older mics are of much higher quality say the unidyne III for example far better than a 57. You could easily change the mics tranny or use a di box or if your- preamp has a guitar input you can use that instead. I don't know how a PE515 sounds put it's probably got a decent capsule in it maybe swap it out with a sm57 58 or even buy a broken 57 off ebay and use the tranny in that.

[Colonel Monk]

Originally Posted by Sim

What are you crazy from my experience shure's older mics are of much higher quality say the unidyne III for example far better than a 57. You could easily change the mics tranny or use a di box or if your- preamp has a guitar input you can use that instead. I don't know how a PE515 sounds put it's probably got a decent capsule in it maybe swap it out with a sm57 58 or even buy a broken 57 off ebay and use the tranny in that.

That's not a bad idea, to grab some sure mic parts to wire it up...

Yeah like I said, when my buddy pulled them out of a paper sack I snickered but it turns out it sounds pretty darn good, and is way better than the crappy modern mic he had been using.

CM

[Bill@WelcomeHome]

Originally Posted by Colonel Monk

That's not a bad idea, to grab some sure mic parts to wire it up...

Yeah like I said, when my buddy pulled them out of a paper sack I snickered but it turns out it sounds pretty darn good, and is way better than the crappy modern mic he had been using.

CM

Sorry Bro, I've never opened up a Shure that wasn't capable of being wired either way. Didn't mean to steer you in the wrong direction.

[Colonel Monk]

Originally Posted by Bill@WelcomeHome

Sorry Bro, I've never opened up a Shure that wasn't capable of being wired either way. Didn't mean to steer you in the wrong direction.

You sure didn't. And I still need to have a closer look.

Either way, it's a freebie that actually works, and I'd much rather have this old mic in damp dark basement than one of my more expensive ones...

Not only that, but many times old stuff is better than new.

CM

[Colonel Monk]

Originally Posted by Colonel Monk

You sure didn't. And I still need to have a closer look.

Either way, it's a freebie that actually works, and I'd much rather have this old mic in damp dark basement than one of my more expensive ones...

Not only that, but many times old stuff is better than new.

CM

Sure enough, there does seem to be a transformer inside. As it's an older design and there's no XLR the transformer is inside the base of the handle just inside the strain relief, and when you look inside the mic from the top with the switch out of the way you can see it. Looks to be glued in there...

So maybe it is possible, but sure can't see how to remove the strain relief or the transformer.

The cable is only two conductor so it would have to be replaced....

CM

[Bill@WelcomeHome]

Originally Posted by Colonel Monk

Sure enough, there does seem to be a transformer inside. As it's an older design and there's no XLR the transformer is inside the base of the handle just inside the strain relief, and when you look inside the mic from the top with the switch out of the way you can see it. Looks to be glued in there...

So maybe it is possible, but sure can't see how to remove the strain relief or the transformer.

The cable is only two conductor so it would have to be replaced....

CM

Yeah, but if the spec sheet says it is HiZ only, then that is the way that it is. ( unless you pull the transformer. The transformer is not intended to be removed but is removable, you can search for the various "take the transformer out of the SM57" to learn how. Then you might have to do more, but it's more than I know about.) All of this is just too much work for a simple basement rehearsal rig, you're going to be well within the operating distances for HiZ, just plug it in and use it in good health.

[Colonel Monk]

Originally Posted by Bill@WelcomeHome

Yeah, but if the spec sheet says it is HiZ only, then that is the way that it is. ( unless you pull the transformer. The transformer is not intended to be removed but is removable, you can search for the various "take the transformer out of the SM57" to learn how. Then you might have to do more, but it's more than I know about.) All of this is just too much work for a simple basement rehearsal rig, you're going to be well within the operating distances for HiZ, just plug it in and use it in good health.

OK, got it.

I had to go back to high school for a few minutes, now I understand what's happening. I was thinking that if it had a transformer I might have a chance of rewiring it - but that_won't_work.

Makes more sense to me now why this mic had a nice hot signal and why I've always hated using regular lo-Z mics thru an unbalanced cable into a hi-Z input, like an old 4 track or powered mixer. This mic into hi-Z works fine, regular lo-Z mics into 1/4" input is weak. I always knew this to be the case but an hour of googling and the reason behind it is a lot clearer.

Thanks for the help guys, we will be using them as is.

CM