Safe Speed Forums

And from someone in the IT section of a highway company -"we had reports of e mails being quarantined , with no reason , till we spotted "hardcore " in the message . - "-----

We have even had messages from a Mr Hancock put in the sinbin. Mind you, he does work for a firm with "BJ" in the company name.

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Malcolm W.
The views expressed in this post are personal opinions and do not represent the views of Safespeed.

Eh? Why would anyone use 500k for that? You start of with a nice low source impedance of a couple of hundred ohms at most and then squander the adavatage with a 500k pot? There's definitely something that someone doesn't know here.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

Pot - from days of the outside loo- thought it was something you found under -----

On guitars you use the 500k pot as a volume or tone control. The switch part of the one shown is electrically independent of the pot and is used for switching pickups on/off without needing to drill new holes in the guitar.

It wouldn't matter much if the amplifier had a decent input impedance, say at least 4x the output impedance of the source (the pot). The max possible output impedance of a 500k pot is only 125k, so the following amp will need to be at least 500k - surely many amps qualify?

Disclaimer: I don't know much about guitar setups....

I don't understand that 100% but yes, guitar amps are high impedance and 500k or 250k are the stock values for control pots

Actually it matters loads when interference comes along, and with longer cables the cable capacitance is probably starting to roll off the higher harmonics - both because we squandered a nice low source impedance.

I can't figure out why they might do that. Perhaps it's to mix with a nasty passive tone control?

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

To get around the high frequency losses of the cable, many guitars have a small capacitor in parallel with the volume pot which lets the high frequencies through as the volume is lowered.

It should also be remembered that a guitar has a very limited frequency range, and that the final output device is even more limited - typically one or more 12" speakers.

Most guitar circuits still follow the basic design of the very first electric guitars (1930), and certainly haven't changed since the fifties. When attempts are made to change things there is generally a high level of resistance (sorry about the pun), because if it worked for Hendrix then it doesn't need to be changed. High impedance pickups (well mainly high reactance) come from using lots of turns to try and get high signal levels and reduce noise.

We have had low impedance pick-ups but they require active circuitry (an amp) on the guitar to avoid noise and to feed the amps designed for the standard pickups. But for many adding a battery adds another failure point, and besides if it worked for...

We also now have virtual guitars - the earlier ones using six way pickups to create midi data and a synth setup to generate the sound, but these always had limitations because it is very hard to get midi to convey the detailed nuances of pick noise, scrapes etc. The most amazing setup however is from Line-6 with their Variax which digitally samples then remodels the sound to produce anything you want from a guitar that looks like it has no pickups. Again user resistance is high, despite amazing sound, but some of that is down to quality and feel (the frets are not dressed well). I want one - with a Vetta II amp, and pedal board which gives you two virtual amps and any guitar (and turning) you want switched by a single pedal press.