SuaveRecords
Ninja kick the dam rabbit
tittle says it all. what is impedance? im getting a tube preamp. and it has variable impedance. googles not helping me much right now so i thought id come here. any one?
Whats Variable Impedance???
- Thread starter SuaveRecords
- Start date
That would be impedance that is variable...
Impedance is the measure of resistance only present in an energized circuit... As opposed to pure resistance which is present in all circuit states...
jhbrandt
Acoustic Design
If you are buying a tube pre with variable impedance... very good. This means that the pre has a switch that will select different taps on the input transformer, giving the microphone a different load. This brings out some nice qualities in some mics, particularly vintage mics with transformer outputs. Some mics will not be affected at all.
If you have or plan to have some vintage mics. This type of pre may work very well for you.
If you have or plan to have some vintage mics. This type of pre may work very well for you.
SuaveRecords
Ninja kick the dam rabbit
can some one explain it to like i have NO clue what im talking about. cuz i don't lol. that first reply by mofo went right over my head.
SuaveRecords
Ninja kick the dam rabbit
ok now that i can understand. so i can tune the impedance to what sounds best with each mic?
mshilarious
Banned
Or that the amp has a pot that varies the input resistance.
Ok... well then... Impedance that is not fixed... that you can change...
...how's that?
mshilarious
Banned
Well let's see. The units you like aren't cheap, because multitap input transformers and rotary switches are very expensive parts. A pot is cheap. He doesn't know what impedance is, so do you think he just dropped $1K+ on a pre?
If you "hate to mention" gear like the ART Gold series, you will probably end up feeling very uncomfortable here, because most people here don't have high-end budgets.
SuaveRecords
Ninja kick the dam rabbit
lol you're explaining what it means to VARY the impedance. i understand what "vary" means. what i didn't understand was impedance. lol
thanks for trying to help but you're defining the wrong term.
SuaveRecords
Ninja kick the dam rabbit
lol how did you know that's what i was getting??? is the Art Gold the only tube mic preamp with variable impedance(under 1k)?
mshilarious
Banned
I think so. And don't worry, it's a very good preamp. Find some NOS American or European tubes to swap in, but don't pay too much for them. I am somewhat allergic to paying more than $5 for a tube . . . I just check eBay for somebody dumping a big box of vintage tubes--not NOS (new-old-stock), so there will be dogs in the box, but enough keepers to make it worthwhile. Throw out the dead tubes, keep the ones you really like, and then I resell the tubes I didn't like as tested and working . . . you can even make money swapping tubes that way!
I am a cheap, cheap man
antichef
pornk rock
Yeah, I'm an electrical ignoramus (a curate in the Order of the Electrical Ignorami, in fact), and these concepts are only very slowly sinking in -- let me take a stab at a dummies description, which will probably be wrong in some aspect, and hopefully corrected by the non-ignorami.
Electricity flows as Direct Current (DC) or Alternating Current (AC) - DC has the electrons flowing through a circuit, AC has them jostling back and forth really fast (60 times per second (60hz) at a wall socket in the US or 50hz in most other places). (actually, compared with most other things having to do with electricity and sound waves, that's not very fast, but you get it)
DC is easier to start with -- Voltage (V) is a measure (volts) of the force pushing the little electrons, Resistance (R) is a measure (ohms) of what's pushing back on them, and trying to keep them from moving, and Current (C?) is a measure (amperes) of how much electricity is flowing. The electrical non-dummies have set things up so that C=V/R (Ohm's law, often stated with different letters standing for the same things), by the way. It's important for me to remember that these measures are extremely useful engineering concepts that approximate what's really going on, but probably don't exactly describe what's going on, but are close enough that we can use them to make all the cool electric stuff happen.
In AC, the Resistance concept doesn't apply exactly, so that's why we have to use Impedance, which resembles resistance, but accounts for the complexities introduced by the jostling and wave-form characteristics of AC. It's also measured in ohms.
http://en.wikipedia.org/wiki/Electrical_impedance
Anyway, I'm another happy Digital MPA owner (same as the MPA Gold, but with A/D conversion) - I use the impedance control all the time. I'm usually happier with high settings than with low ones, and yes, I notice the difference when using a transformer-balanced mic, including ribbons, most of the dynamics I have, and some of the condensers. Different impedance in the AC circuit between the preamp input and the mic transformer makes the mic transformer behave in slightly different ways. Good stuff!
Electricity flows as Direct Current (DC) or Alternating Current (AC) - DC has the electrons flowing through a circuit, AC has them jostling back and forth really fast (60 times per second (60hz) at a wall socket in the US or 50hz in most other places). (actually, compared with most other things having to do with electricity and sound waves, that's not very fast, but you get it)
DC is easier to start with -- Voltage (V) is a measure (volts) of the force pushing the little electrons, Resistance (R) is a measure (ohms) of what's pushing back on them, and trying to keep them from moving, and Current (C?) is a measure (amperes) of how much electricity is flowing. The electrical non-dummies have set things up so that C=V/R (Ohm's law, often stated with different letters standing for the same things), by the way. It's important for me to remember that these measures are extremely useful engineering concepts that approximate what's really going on, but probably don't exactly describe what's going on, but are close enough that we can use them to make all the cool electric stuff happen.
In AC, the Resistance concept doesn't apply exactly, so that's why we have to use Impedance, which resembles resistance, but accounts for the complexities introduced by the jostling and wave-form characteristics of AC. It's also measured in ohms.
http://en.wikipedia.org/wiki/Electrical_impedance
Anyway, I'm another happy Digital MPA owner (same as the MPA Gold, but with A/D conversion) - I use the impedance control all the time. I'm usually happier with high settings than with low ones, and yes, I notice the difference when using a transformer-balanced mic, including ribbons, most of the dynamics I have, and some of the condensers. Different impedance in the AC circuit between the preamp input and the mic transformer makes the mic transformer behave in slightly different ways. Good stuff!
Harvey Gerst
New member
Here's an old post from Dan Kennedy, the designer of the Great River preamps:
Well, in general, a dynamic type mic, including ribbons is sensitive to the load, because it is after all a generator.
When operated into a light load, the higher frequencies will typically be extended. With a heavier load i.e. lower input impedance, the high end will drop. At some point the lower impedance will also interact with the inductance of the mics output (be it a matching transformer or the coil itself) and this will cause the low end to start rolling off as well, giving a honky midrangy tone.
With some condensers, those with output transformers and wimpy amplifiers, like KM-84's, original U87's you'll get fairly similar responses plus that always desirable distortion boost when that poor little FET is driving a low-Z input.
Others, like most Schoeps, about half of the Chinese knock-offs and most of the new Neumanns don't really care. The other half of the knock-offs will behave like the KM-84, but worse because they have truly crappy output transformers.
Most mics are designed for load impedances of 1K to 3K for "flat" response.
What's it mean for you? Try it, use it like an equalizer, be sure you aren't causing the mic to puke with too low an impedance and have fun. You won't cause any damage to the mics, it just may not sound good. It might be louder, but be careful with that, listen to the characteristics, not volume.
Well, in general, a dynamic type mic, including ribbons is sensitive to the load, because it is after all a generator.
When operated into a light load, the higher frequencies will typically be extended. With a heavier load i.e. lower input impedance, the high end will drop. At some point the lower impedance will also interact with the inductance of the mics output (be it a matching transformer or the coil itself) and this will cause the low end to start rolling off as well, giving a honky midrangy tone.
With some condensers, those with output transformers and wimpy amplifiers, like KM-84's, original U87's you'll get fairly similar responses plus that always desirable distortion boost when that poor little FET is driving a low-Z input.
Others, like most Schoeps, about half of the Chinese knock-offs and most of the new Neumanns don't really care. The other half of the knock-offs will behave like the KM-84, but worse because they have truly crappy output transformers.
Most mics are designed for load impedances of 1K to 3K for "flat" response.
What's it mean for you? Try it, use it like an equalizer, be sure you aren't causing the mic to puke with too low an impedance and have fun. You won't cause any damage to the mics, it just may not sound good. It might be louder, but be careful with that, listen to the characteristics, not volume.
That doesn't have anything to do with folding paper does it?
Like folding schematics into little paper birds...
antichef
pornk rock
Exactly. And then trying to assemble the kit without unfolding them
SuaveRecords
Ninja kick the dam rabbit
Apex 460, mxl 4000, mxl 603s, AKG something or other lol. and sm 57's as well as a lot of the Audix D' mics.