1. Home
  2. Electronics Design
  3. A-F circuits

A-F circuits

Since inductance and capacitance for audio frequency filtering and other purposes tend to be very large why not "shift" the audio spectrum up to minimize there size?

For example, for a shunt-fed power amplifier(uses inductor instead of resistor to block ac so all the ac power gets shunted to the "ac load"(speaker)) the inductor must be chosen such that w*L >> R and 1/wC >

8H and C >> 125mF. These are impossibly large and hence the shunt fed method is kinda useless for a full band af amplifier.

Increasing w to 100hz reduces the values of L and C by 100 which helps but cuts into the low frequency response.

But if we shifted the audio band up, say, to 1Mhz then it would reduce their values by a factor of 1M. (even shifting up 1khz is hugely significant)

So it looks good in theory but what is the real problem here? Is there any easy way to "shift" the audio signals with little distortion(ADC->DSP->DAC?) where one could benefit from such things? (maybe am or fm would work too?)

Reply to
Jon Slaughter
Loading thread data ...

(BTW, I guess in ss it's not as much an issue because of the high impedences that are used. I'm mainly talking about tube audio amps where impedence matching is a bigger deal)

Reply to
Jon Slaughter

"Jon Slaughter"

** A name which will live in infamy ......

** " What goes up must come down " - Isaac Newton.

** 1 Hz ?????????

Purest idiocy.

** In reality, L can be 100mH and no C is needed - at all.
** " What goes up must come down " - Isaac Newton.

** " What goes up must come down " - Isaac Newton.

Is there any easy way to "shift" a steaming great FUCKWIT like Slaughter from ever posting his asinine, verbal excreta on SED again ?

No kind of cruel, public humiliation is beyond consideration.

The worse, the better.

..... Phil

Reply to
Phil Allison

If you wern't such a nut case you might be usefull... How does your sneaky ass get through my filters!?!??!

Reply to
Jon Slaughter

, L >>

hod

t

eir

any

C?)

)

This is a very silly proposition - for once I agree with Phil Allison.

There is the germ of a good - if old - idea in there which was long ago embodied in class-D (switching) amplifiers.

Getting a suitable switching drive waveforn out of a digital audio system isn't all that difficult, though a really fast clock oscillator

- several hundred MHz - is required if you want 14-bit amplitude resolution on the 10kHz components and don't want to bother with programmable monstables.

A guitar amplifier based on the approach would have to digitise the signal coming in from the guitar, which is neither difficult nor expensive.

-- Bill Sloman, Nijmegen

Reply to
bill.sloman

"Jon Slaughter"

** A name which will live in infamy ......

** " What goes up must come down " - Isaac Newton.

** 1 Hz ???????

Purest idiocy.

** In reality, L can be 100mH and no C is needed - at all.
** " What goes up must come down " - Isaac Newton.

** " What goes up must come down " - Isaac Newton.

Is there any easy way to "shift" a steaming great FUCKWIT like Slaughter from ever posting his asinine, verbal excreta on SED again ?

No kind of cruel, public humiliation is beyond consideration.

The worse, the better.

..... Phil

Reply to
Phil Allison

This was done in the 70's, for a speech clipper/ limiter for "Ham use"

formatting link

martin

Reply to
Martin Griffith

I concur with Mr. Sloman

martin

Reply to
Martin Griffith

It seems to basically use that idea but for clipping instead of filtering but looks like it should work. I'm just wondering how well it would work for hi fi?

Reply to
Jon Slaughter

He's Jon Slaughter.

That's punishment enough.

Reply to
a7yvm109gf5d1

You are describing a single ended class A amplifier that works down to 1 Hz. I doubt that one ever was built. Where do you find a speaker that puts out 1 Hz?

Easy enough to shift audio frequencies up, but you lose the octave relationship. Taking your example of a 1 Hz HPF, if you shift all frequencies up by 1 MHz, then you would have to design a filter that has 3 db loss at 1.000001 MHz, and infinite loss at 1.000000 MHz. Such a filter can not be built. The converse is often done. That is frequencies are shifted DOWN to get a desired filter shape. Virtually every radio made since about 1935 does that; so does your TV.

Tam

Reply to
Tam

This looks interesting though a bit pricey.

formatting link

GG

Reply to
Glenn Gundlach

Sure. But then only my dog could hear my stereo.

--
Paul Hovnanian	paul@hovnanian.com
-----------------------------------------------------------------------
Have gnu, will travel.
Reply to
Paul Hovnanian P.E.

They are called shakers.

Reply to
JosephKK

formatting link

Reply to
Ben Bradley

I just found a competing item:

formatting link

Reply to
Ben Bradley

On Nov 9, 5:05=A0pm, Ben Bradley wrote: > On Sun, 09 Nov 2008 18:54:13 -0500, Ben Bradley >

Cool - should bring the price down. How do you explain to the wife that your sub-woofer needs to be cleaned and lubed? It was bad enough when they need to be re-foamed.

GG

Reply to
Glenn Gundlach

Hey, there is an idea for that "How to make money from electronics" thread. Plenty of Audiophools will lap it up. Phil did a frequency shifter project, start there and work your way up.

Watch this space for a Monster Cables matching "frequency shifter" black boxes. They'll catch on that there is a buck or two to had here.

Dave.

Reply to
David L. Jones

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.