Author Topic: Please help out a noob (Read 594 times)

bigredbass · « **Reply #15 on:** April 20, 2011, 09:36:30 PM »

THIS is why I only use wrenches around a bass, and not a soldering iron: What does the impedance have to do with output, vis-a-vis driving the front end of an amp to distortion, etc.?

J o e y

hydrargyrum · « **Reply #16 on:** April 21, 2011, 07:12:21 AM »

Some pedals interact almost as though they were part of the circuitry of the guitar itself. Take for example the stratoblaster (or the active cords that Alembic was selling recently). It doesn't just boost the signal, it actually improves the spectrum of the frequency response. My Zvex Fuzz Factory will self oscillate in several settings, producing squeals and tones reminiscent of analog synth. I can actually change the pitch of these squeals by turning the volume and tone controls on my (passive) guitar. If you place anything that acts as a buffer between this pedal and guitar (such as the aforementioned stratoblaster, or Alembic active electronics), you lose this effect and end up with a flat fizz-less tone (keep this in mind if you are Muse fan, although I have to admit I'm not). You'll experience the same effect with Colorsound One Knob Fuzzes, Tonebenders, Fuzz Faces, and other simple old-school circuits. I'll admit that I don't know the technical specifics of why this happens. I do know that pedals like the Tube King which rely solely on the level of the signal, and which are driven by tubes, do not display this effect. Boss and similar Distortion pedals also don't display this characteristic. It must be related to how the guitar interacts with the bias of the transistors of these circuits, versus the plate voltages of tubes, or circuits which have been designed to emulate tubes. I've been trying for some time to wrap my head around how impedance differs from resistance, but I have yet to understand it. Paging David Fung. . . Dr. Fung?

(Message edited by hydrargyrum on April 21, 2011)

terryc · « **Reply #17 on:** April 21, 2011, 08:09:25 AM »

I ain't an expert but what I know from my teenage years when I did amateur electronics is that the germanium fuzz units are clipping amplifiers..that is how they work, they take the low output signal from the guitar and jump it up until it clips, if you look at a circuit diagram of a Vox/Coloursound Tonebender you see that the two transistors are connected. Now feeding a relatively high output signal from an active guitar such as an Alembic this will be 'double clipped' if you get my drift and produce too much fuzz.
I guess the moderner pedals have built in buffers to stop this happening, sort of like the two choice of inputs on bass amps - passive & active, the active input puts a 5 - 15 dB pad on the signal.
So I think that is why these old units don't work with Alembic guitars but I guess David Fung has the proper explanation

hydrargyrum · « **Reply #18 on:** April 21, 2011, 09:03:07 AM »

Terry,

What you describe is exactly what I've experienced. I've produced exactly the same sound from passive guitars that had a signal that was too hot for these devices. Looking around a bit, I found that Impedance is analogous to Resistance. The difference is that Resistance refers to DC whereas Impedance is AC. As we all know, a guitar string produces an AC current (it vibrates one way then the other in the magnetic field of the pickup). Low impedance circuits have lower current, and therefore have to be boosted to a higher gain level (hence the double clipping), whereas High impedance have sufficient current by themselves in traditional applications. The trade off is in frequency response across the spectrum (low impedance have better response). It's all becoming clear/coming back to me now.

(Message edited by hydrargyrum on April 21, 2011)

mario_farufyno · « **Reply #19 on:** April 21, 2011, 03:17:15 PM »

2 cents...

Impedance is the summ of all resistances in a circuit, as capacitive reactance from a Capacitor and inductive reactance from a Inductor can change overall resistance. As they change according to frequency, you may call it AC, but in fact audio gears are just fed in AC but works with modulated DC internally (changes Voltage but not Direction).

A PU can be seen equaly as a resistor and some sort of inductor (and the Tone Pots are variable resistors associated with Capacitors as well). So there is a constant changing charges being summed in a way we call them Impedance (to make clear it is different from ordinary resistance).

sonicus · « **Reply #20 on:** April 21, 2011, 05:30:34 PM »

1 cent here as well... short version______
Resistance or R as a DC concept where as Impedance involves reactance which varies with frequency as a result of inductance and capacitance.

Impedance or Z where as there is AC or fluctuating DC , the Sum of resistive and reactive ,variable with frequency .

(Message edited by sonicus on April 21, 2011)

hydrargyrum · « **Reply #21 on:** April 22, 2011, 07:37:24 AM »

From Wiki:

* The magnitude of the complex impedance is the ratio of the voltage amplitude to the current amplitude.
* The phase of the complex impedance is the phase shift by which the current is ahead of the voltage.

It's becoming less and less clear.

sonicus · « **Reply #22 on:** April 22, 2011, 08:43:25 AM »

Interesting articles;
http://www.teamrocs.com/technical/pages/resistance_impedance.htm
http://www.esu.edu/physics/cohen/phys132/chapter10.
http://www.physlink.com/education/askexperts/ae517.cfm

crobbins · « **Reply #23 on:** April 22, 2011, 11:39:23 AM »

bigredbass · « **Reply #24 on:** April 22, 2011, 11:02:34 PM »

My many thanks to you all for trying to explain this to my not-electronically-adept self. Now, where's those feeler guages . . . .

J o e y

mario_farufyno · « **Reply #25 on:** April 23, 2011, 05:43:43 AM »

It looks price is the must on this Tone Suck.

Last night our drummer came complimenting me for the vintage tone and asked me what did I did (he really doesn't likes Alembic's open tone). I've had to explain him that my strings are older than 3 months now...

(Message edited by Mario Farufyno on April 23, 2011)

mike1762 · « **Reply #26 on:** April 24, 2011, 08:49:32 AM »

That's pretty funny Mario. When I started playing with my current band I could tell that they REALLY didn't know what to think of the crystal clear tones coming from my bass.

David Houck · « **Reply #27 on:** April 24, 2011, 01:23:27 PM »

My one cents. At the gathering last week there were at least four guitar players playing Alembics up on the stage (may have been more but four's all I can recall at the moment) and all of them had great tone. At least one of them was using his pedal board through someone else's rig, but still sounded great.

hydrargyrum · « **Reply #28 on:** April 24, 2011, 01:57:16 PM »

My last comment in this regard would be that I still think it is best to try things through your own rig if possible, so there aren't any surprises. And now, I'm out of change.

lidon2001 · « **Reply #29 on:** April 24, 2011, 05:34:35 PM »

Some line art I've been working on: