Thievin' Heathen
53 posts
Oct 14, 2012
11:28 AM
|
So, I am plugging my SM58 into a guitar amp. I am plugging a 3 pin XLR cable into the mic, the cable into a XLR to ¼:” pigtail which, I don’t believe has a transformer in it. I can plug it into the high gain or low gain jack on the amp and play the hell out of it. I have purchased an XLR to ¼” cable – same story. I have purchased an XLR to ¼” impedance matching transformer and I don’t notice any difference in sound, tone, gain, feedback…, no difference when I use it.
I am seriously contemplating an Ultimate Mic for my next major purchase and I have read, on the website, that I need the transformer for the mic to perform correctly. I read the same thing over at the Audix website in regards to their Fireball V.
I currently do not run the transformer when I use my SM58. My Green Bullet has a ¼” plug on the cable coming out of it (stock) and my Sonotone CM10A is a high impedance mic with a ¼” plug all of which will work in either the high or low gain jack on my amp.
Right now I am just doing my own thing, and whatever fits the mood of the moment, but what is correct? And when I buy that Ultimate 58, what is correct?
Last Edited by on Oct 14, 2012 11:29 AM
|
atty1chgo
510 posts
Oct 14, 2012
11:45 AM
|
A standard Shure SM58 is a low impedance mic, isn't it? I find it hard to believe that you cannot hear a difference plugging a low impedance microphone into an amp without an impedance matching transformer. YOU DO need a transformer for the mic to perform as it should.
I just bought an Audix in-line transformer for $24.95 (shipping included) on eBay for my Low-Z mics. Female XLR with an in-line transformer out to a 1/4 inch phono plug. Everyone else was $24.95 plus shipping, or else drive to Guitar Center to waste time and gas. I suggest that you buy one. That will avoid the transformer being plugged directly into the amp jack, where it sticks out and can be banged around.
Last Edited by on Oct 14, 2012 11:48 AM
|
SuperBee
623 posts
Oct 14, 2012
12:16 PM
|
I bought a transformer for my 58 and thought it made no difference. Some time later I found the switch on it.
----------
|
Thievin' Heathen
54 posts
Oct 14, 2012
1:17 PM
|
I think my Peavey pigtail is a transformer.
http://www.parts-express.com/pe/showdetl.cfm?partnumber=241-5384
Transformer built into 1 end at the connector? A couple of hundred turns of some very thin wire?
I also have a 15' cable that is XLR to 1/4" and claims to be high Z. I wonder if it also has a built-in transformer? If it claims to be a "Balanced" cable, do I need a transformer?
EDIT
O.K.
After some experimentation here.., the Peavey pigtail is a transformer. It has been part of my rig for 20 years so I just quit thinking about impedance matching until I acquired a couple of more mics (ebay). The XLR to ¼”, 15’ cable is just an XLR female to ¼” male cable.
Last Edited by on Oct 14, 2012 3:10 PM
|
rharley5652
659 posts
Oct 14, 2012
11:14 PM
|
@ Thievin' Heathen,. ya say ya plug into a guitar amp. Is it a Tube amp ? Or is it a solid state amp ? You won't notice any difference in sound, tone, gain, feedback,with the solid state . ----------
------------click Link Below -----------
Simply Unique Kustom Mic's By Rharley
|
atty1chgo
511 posts
Oct 15, 2012
3:04 AM
|
@ rharley -
"You won't notice any difference in sound, tone, gain, feedback,with the solid state."
-- Not true. Impedance is impedance.
|
Greg Heumann
1814 posts
Oct 15, 2012
9:03 AM
|
@Thieven'
First - if you're interested in an Ultimate mic, all you have to do is email me and I will be happy to answer all your questions. This impedance stuff confuses everyone - they don't teach it to you in High school! That's what I'm here for.
A transformer is NOT required with an Ultimate mic IF you choose one of the high impedance setups. ANY of the available configurations can be connected to ANYTHING - the only issue is in which cases you'll need some sort of adapter. There is a table on the Ultimate Mics page (right column, half way down) that shows, for any configuration, what is required to connect it to anything.
XLR to 1/4" cables (without transformers) are for high impedance mics. You can physically connect them to a low impedance mic and you will get some sound - however you will only get half of the mic's output due to the difference between balanced and unbalanced wiring of the XLR connector. You will also get thin tone due to the impedance mismatch. These cables come in 2 flavors - "Pin 2 Hot" and "Pin 3 Hot". The cable has to match the mic or you won't get any sound at all. ---------- /Greg
|
Thievin' Heathen
55 posts
Oct 15, 2012
7:23 PM
|
Greg,
I will be in touch shortly, just to make sure I buy exactly what I want. My main problem here is I recently added several new variables to the equation and have not been paying close enough attention.
We spoke at SPAH, but I was watching my budget real close that day. I was afraid if I started spending I wouldn't be able to stop.
|
rharley5652
660 posts
Oct 15, 2012
8:54 PM
|
@atty1chgo
For audio circuits, is it important to match impedance?
Not any more. In the early part of the 20th century, it was important to match impedance. Bell Laboratories found that to achieve maximum power transfer in long distance telephone circuits, the impedances of different devices should be matched. Impedance matching reduced the number of vacuum tube amplifiers needed, which were expensive, bulky, and heat producing.
In 1948, Bell Laboratories invented the transistor — a cheap, small, efficient amplifier. The transistor utilizes maximum voltage transfer more efficiently than maximum power transfer. For maximum voltage transfer, the destination device (called the "load") should have an impedance of at least ten times that of the sending device (called the "source"). This is known as BRIDGING. Bridging is the most common circuit configuration when connecting audio devices. With modern audio circuits, matching impedances can actually degrade audio performance. ----------
------------click Link Below -----------
Simply Unique Kustom Mic's By Rharley
|
5F6H
1395 posts
Oct 16, 2012
3:43 AM
|
@ RHarley - Nevertheless, a lo-Z mic puts about about a 20th of the signal voltage of a hi-z mic...the transistor doesn't account for that. Plug your mic/guitar into a SS PA's lo-Z 1/4" input & you'll see what I mean.
If performance is severely degraded by the relationship between source & load, then by definition, it isn't "matched". Input impedances are usually expected to be many times greater than the signal sources that connects to them to prevent loading of the circuit. That's common to tube & SS.
In reality a "match" may occur over a wide range of impedance values, within the definitons of "high" & "low".
---------- www.myspace.com/markburness
http://www.facebook.com/markburness
Last Edited by on Oct 16, 2012 3:45 AM
|
LIP RIPPER
634 posts
Oct 16, 2012
10:28 AM
|
I have one of those peavey cables with the built in impedance matching transformer. They do exist or at least they were produced at one time.
|
atty1chgo
513 posts
Oct 17, 2012
1:57 AM
|
@rharley - see Greg Heumann's post above.
|
Greg Heumann
1815 posts
Oct 17, 2012
8:42 AM
|
Yeah, I will reiterate- impedance matching matters - especially for tube amps - but the real problem lies in the fact that low impedance (XLR<-->XLR cables are wired "balanced" and high impedance cables (XLR<-->1/4") are not. This puts the signals on different pins of the XLR connectors. This is a (fortunately rare) case of "just because you can physically connect it doesn't mean it is correct." If you use a high impedance cable to connect a low impedance mic to an amp, you will lose a LOT of the mic's signal, whether there is an impedance mismatch or not. ---------- /Greg
|
atty1chgo
515 posts
Oct 18, 2012
3:03 AM
|
Just got an Audix T-50K Inline Impedance Matching Transformer in the mail. What a great and solidly constructed product. Well worth a look.
|
A440
37 posts
Oct 18, 2012
10:34 AM
|
I'm also using the Audix T-50K with my SM57. It is an excellent product.
|
rainman
35 posts
Nov 18, 2012
5:24 PM
|
Does it matter where the I.M.T is located? Can it be at the amp end rather than the mic end? It would be less obstructive at the amp and just run a regular XLR cable to mic. Thanks
|
Greg Heumann
1849 posts
Nov 18, 2012
5:45 PM
|
@Rainman - it is most common to use the IMT at the amp end of the cable. There is an advantage to that - which is that there is far less signal loss over a low impedance mic+cable than there is over a high impedance mic+cable. If you're using a low impedance mic, and put an IMT at the mic - then you're running high impedance over the cable to the amp and after about 20' you will be able to hear some signal degradation. When you put the IMT at the amp end, the high impedance run is only an inch or so, from the inside of the IMT to the 1/4" plug. You could use 100' cable from the mic to the IMT and have very little signal loss. ---------- /Greg
|
rainman
36 posts
Nov 19, 2012
5:07 AM
|
Thanks Greg, that makes it simple.
|