SM57 Impedance Gizmo
- Thread starter load_bandit
- Start date
zmetallica
Member
any suggestions to fix the impedance problem with the 57 going into a mackie VLZ pro mixer? whats the cheapest easiest option? i know barely anything about sodering and adding on resisters (though i've done it with some things, i'm not experienced enough to mess with cables and mics) i can't afford a preamp for all my mics. any idea about an impedance booster adapter or something that would go in between the mic and the mixer's signal flow?
Glenn Fricker
Very Metal &Very Bad News
zmetallica said:
Yeah, buy a better preamp.
Seriously though, look through your user guide & figure out the preamp's impedance. I'll help you with the rest.
-0z-
zmetallica
Member
thats the answer to everything, as the mixer ain't too great, but gets the job done. I am looking into buying the MOTU Traveler, but i doubt that'll be any better impedance wise.OzNimbus said:Yeah, buy a better preamp.
-0z-
Keiffer said:Fucking A...
I'm talking a cable with a resistor in it. it's just an option... yeah transformers will work, so willl the resistor. to pick a value it's best to know the preamp impedance you're going to use it with.
comparing $1K+ preamps to this cable is... well absurd. the preamp has a lot more going on than just loading the mic.
as for your technical buddy... he's right. but you've totally missed the point. FWIW, I have a EE degree of 25 years and have done this shit for years even longer.
you don't have to use the cable, but it's a very good and dirt cheap option.
and no, transformers do not auto match. transformers are basically inductive and have an impedance.
as for removing the 57 transformer, here's a clip comparing with and without.
57 with - 57 w/o - i5
It's all right man, no need to get worked up. And yeah, I've got the point. Even though he told me what to do, I said fuck it...I'm just going to use a resistor since it seems to work for some other guys. I'd like to learn more about electronics and such, beings as how that's very important to what we do, so that's why I keep talking.
Anywho, thanks for the help with all this junk.
MusicKey, I'll do it for you if I ever get my hands on a decent camera. If you want as much text detail as I can give, PM me, but don't be afraid to do it as it's really simple (I did it half-asleep without having seen a single picture, you should be fine).
Jeff
Jeff
Glenn Fricker
Very Metal &Very Bad News
I recorded some clips earlier today. I'll get around to posting them tomorrow morning. I just got off work & need some z's.
Keiffer
Member
- Apr 14, 2006
- 505
- 0
- 16
Here's how I removed the transformer in my 57...
the Mic capsule has to be detached from the transformer. I believe I clipped the leads or unsoldered them
The plastic XLR connector and leads should also be removed. this leaves the mic body with the transformer inside.
have a pot of boiling water and put the mic body with the transformer in the water. I don't remember how long, but probably several minutes. too long in the hot water and the paint will flake off. now remove the mic from the water and pull out the transformer. you'll need to be able to handle it... it's hot. also, the stuff inside the mic body holding the transformer is gooey and messy.
after the transformer is out, you'll need to run leads from the capsule to the XLR connector.
that's about it.
the Mic capsule has to be detached from the transformer. I believe I clipped the leads or unsoldered them
The plastic XLR connector and leads should also be removed. this leaves the mic body with the transformer inside.
have a pot of boiling water and put the mic body with the transformer in the water. I don't remember how long, but probably several minutes. too long in the hot water and the paint will flake off. now remove the mic from the water and pull out the transformer. you'll need to be able to handle it... it's hot. also, the stuff inside the mic body holding the transformer is gooey and messy.
after the transformer is out, you'll need to run leads from the capsule to the XLR connector.
that's about it.
Glenn Fricker
Very Metal &Very Bad News
Great explanation Keiffer - I'm much too disorganized to follow with this kind of thing. Oh, and mine took about ten minutes to boil, others' results may vary.
Jeff
Jeff
I did the gizmo and yeah, there was a difference! It also made me think: I have presonus firepod and it has a 1,3k ohm preamps, and I used a 680ohm resistor. Does that mean that the impedance is now 1300 - 680 = 620? The sm57 is rated at 300ohm? should I use like a 1 k ohm resistor to match the 300 ohm?
GuitarHack
Krank it UP!
Disclaimer: I am EXTREMELY nOOb when it comes to recording (as you may soon hear if you download the samples
). These samples were originally recorded as a quick trial for myself and not to be posted so they are not played brilliantly and do NOT sound all that nice 
uke: . They are just the RAW sample as recorded with no post anything except rough level-matching. I didn't reamp, I played the samples twice each so there will be differences to start with.
Gear Used:
BC Rich Warlock Platinum Pro with EMG81 in Bridge (Tuned E-Flat)
Krank Revolution
Mesa Standard 4X12 Rectifier Cabinet
Shure SM57
M-Audio Firewire Solo
Guitar Tracks Pro 3
The M-Audio's Impedance is 1.5kohms (stated in the manual) so I used an 820ohm resistor to give a new supposed value of 530 ohms (given that impedance is a measure of resistance and inductive/capacitive reactance (from vague memory 15 years ago) and I have changed the resistance only, the value is only assumed since the original 1.5kohms isn't purely resistive
)
I hope they are of some use to somebody (not sure if they are to me )
http://www.keepmyfile.com/download/85cd511108507
). These samples were originally recorded as a quick trial for myself and not to be posted so they are not played brilliantly and do NOT sound all that nice uke: . They are just the RAW sample as recorded with no post anything except rough level-matching. I didn't reamp, I played the samples twice each so there will be differences to start with.Gear Used:
BC Rich Warlock Platinum Pro with EMG81 in Bridge (Tuned E-Flat)
Krank Revolution
Mesa Standard 4X12 Rectifier Cabinet
Shure SM57
M-Audio Firewire Solo
Guitar Tracks Pro 3
The M-Audio's Impedance is 1.5kohms (stated in the manual) so I used an 820ohm resistor to give a new supposed value of 530 ohms (given that impedance is a measure of resistance and inductive/capacitive reactance (from vague memory 15 years ago) and I have changed the resistance only, the value is only assumed since the original 1.5kohms isn't purely resistive
)I hope they are of some use to somebody (not sure if they are to me
)http://www.keepmyfile.com/download/85cd511108507
Glenn Fricker
Very Metal &Very Bad News
Keessi said:
Following Paul J's Equation, the exact resistance needed would be 448.2696 ohms. Try a 450... it'll be close enough.
Good luck!
-0z-
KeithRT99
BOOSH.
Glenn Fricker
Very Metal &Very Bad News
KeithRT99 said:
There's a pretty subtle tone shift going on. The top end is a little more tamed & the mids are smoother. Not a huge deal, yeah, I know. However, when you start stacking up 12 rhtyhm tracks, a sublte tone shift can add up pretty quickly.
In my own experiments, which I'll post sometime this week, hopefully, I've noticed the Great River impedance switching via transformer produces better & more noticeable results.
-0z-
