Frequency shifters

[Walters]

1.) What does a Frequency Shifter do ?
explain in electronic theory



2.) What are the unit called that take a mono signal and convert to
Stereo i seen them in old consoles?
How do they do this conversion back then?



3.) How did they do tape effects its like they just recorded the tape speeding up
and down how did they record that stick a microphone over the reel to reel
and hear the tape going through the heads and rollers?

[tINY]

1) Are you talking about a pitch shifter or a Ring modulator?

2) Not sure what you are talking about... maybe a pan pot?

3) Not sure what you are talking about. If you hear the transport and not the recording, you are probably right.


Dazed and Confused....



-tINY

[snoopynow]

A frequency shifter (as distinct from a pitch shifter) moves all audio frequencies by a given frequency amount, rather than a musical interval. AFAK, it was developed by the BBC as an anti feedback device, and was used in the Shepards Bush theatre.
Technically, it modulated the audio onto a high frequency carrier wave, filtered off one sideband (technically the most difficult part of the operation) and demodulated using a slightly different frequency.
Small shifts gave deep phasing effects, larger shifts were -interesting, if not over musically useful (frequency differences which were related to a note gave strange harmonic structures, when the note changes, purest dissonance- very Stockhausen)
With the democretisation of harmonisers (which essentially change the speed of incoming signals, and thus maintain musical intervals) the frequency shifter more or less disappeared- I've no idea how to duplicate the effect nowadays.

Stereo synthesisers worked in a number of different ways, but most of them involved splitting the signal into frequency bands which would be panned left and right. One of the simpler ones took a phaser circuit (not a flanger- a phaser is a series of all pass phase shift networks, involving no delay), filtering off the ultra lows (which would come out in mono anyway) and mixing it in phase and antiphase to the two sides- bingo, frequencies spead out and total mono compatibility.
Chris

[gyraf]

Pseudo-stereo from mono can be made by e.g. the TDA3810 IC from Philips. It creates a phase shift at midrange in one channel by using sharp filters. Look up a data sheet for that one if you want to know the theory and workings.

I've never seen any of those in old consoles!

Could you please explain your questions a bit more?

Jakob E.

[klangumwandler]

The frequencey shifter (also known as Klangumwandler) was first developed by Ludwig Heck and Fred Bürck for the studio at Südesetfunk, Baden-Baden. The most well known verisons of the device were made by Harold Bode, who moved to the US (worked for Wurlitzer) after developing some of the first electronic instruments for the Cologne studio. Among several of Bode's own models, there was also a version that was licensed to Moog and fit the standard Moog modular cabinet. This AES paper by Bode should answer most of your questions: "Solid State Audio Frequency Spectrum Shiter," AES Preprint No. 395, 1965.

Here's a picture of an early frequency shifter made by Bode (transformer in-out, hand wired, hand-labled frequency indicator!) for the then-Columbia-Princeton Electronic Music Center (now Columbia Computer Music Center).

Best,

James

[Geoff_T]

Originally Posted by klangumwandler

The frequencey shifter (also known as Klangumwandler) was first developed by Ludwig Heck and Fred Bürck for the studio at Südesetfunk, Baden-Baden. The most well known verisons of the device were made by Harold Bode, who moved to the US (worked for Wurlitzer) after developing some of the first electronic instruments for the Cologne studio. Among several of Bode's own models, there was also a version that was licensed to Moog and fit the standard Moog modular cabinet. This AES paper by Bode should answer most of your questions: "Solid State Audio Frequency Spectrum Shiter," AES Preprint No. 395, 1965.

Here's a picture of an early frequency shifter made by Bode (transformer in-out, hand wired, hand-labled frequency indicator!) for the then-Columbia-Princeton Electronic Music Center (now Columbia Computer Music Center).

Best,

James

Hi

Back in the late 70's, early 80's, the Head of Neve R & D was Dr Martin Hartley-Jones. He held patents on a form of frequency shifting that were put to good use at Neve with the production of teleconference units. You could hold the conference mic right close in front of the loudspeaker and not get feedback.

I can't remember by how much the shift was exactly but it was around 5Hz.



PS I googled his name and he's still going strong!
http://www.cambridgenetwork.co.uk/po...=BF_COMP_10490

PPS Plus he wrote a good book explaining electronic circuits that you can pick up fairly cheaply, used, at Amazon

http://www.amazon.com/exec/obidos/tg...glance&s=books

[snoopynow]

Originally Posted by Geoff_T

Hi

Back in the late 70's, early 80's, the Head of Neve R & D was Dr Martin Hartley-Jones. He held patents on a form of frequency shifting that were put to good use at Neve with the production of teleconference units. You could hold the conference mic right close in front of the loudspeaker and not get feedback.

I can't remember by how much the shift was exactly but it was around 5Hz.



PS I googled his name and he's still going strong!
http://www.cambridgenetwork.co.uk/po...=BF_COMP_10490

PPS Plus he wrote a good book explaining electronic circuits that you can pick up fairly cheaply, used, at Amazon

http://www.amazon.com/exec/obidos/tg...glance&s=books

Yes, I hadn't thought of frequency shifters in many years, and Googled them too. Surrey Electronics (who built the one I used in the early seventies) seem still to exist,
http://reflectionseurope.com/surreyelectronics.html
and there's even a german company, http://www.oldcrows.net/~jhaible/jh_fs2/jh_fs2.htm
who appear either to sell kits or at least give away circuit diagrams for a more modern design.
Chris

[Walters]

What are frequency shifters used for ?


how to use a frequency shifter?


What really is a frequency shifter?


Can someone please make a block diagram for me and to explain the blocks
of the frequency shifter how it works im confussed?

[Geoff_T]

Originally Posted by Walters

What are frequency shifters used for ?


how to use a frequency shifter?


What really is a frequency shifter?


Can someone please make a block diagram for me and to explain the blocks
of the frequency shifter how it works im confussed?

Hi

I can only speak for the device we built at Neve and I don't have a block diagram for it. Basically it was a teleconferencing unit that used a mic pre and a loudspeaker amplifier to amplify the voices of people in conference rooms in two locations. The microphone and loudspeaker were next to each other in the centre of the conference table.

The frequency shifter raised the frequencies the mic picked up so everything was shifted up by 5Hz (or so). The difference with speech is minimal and hardly perceptable but you could hold the mic right up to the speaker and not get feedback despite lots of mic gain and a 25 watt amplifier powering the speaker.

I'm sure that there are other uses in synthesisers but as an anti-feedback device it was bullet proof.

[tINY]

Did you guys use a 5 Hz oscillator and a mixer? If so, how did you filter out the base band?

Or was it considerably more complicated than a ring modulator?



-tINY

[Geoff_T]

Originally Posted by tINY

Did you guys use a 5 Hz oscillator and a mixer? If so, how did you filter out the base band?

Or was it considerably more complicated than a ring modulator?



-tINY

Hi tINY

That's taxing the memory a bit but I believe it had a 5Hz oscillator with + and - phase outputs and these were fed into a pair of MC1495 linear four quandrant multipliers. The output of these was fed through a 5KHz low pass filter to the loudspeaker driving output IC. It had numerous filters to make it suitable for telephone use.

Here's a pdf of the multiplier

http://www.ee.washington.edu/stores/...ear/mc1495.pdf

PS It was designed for private 4 wire telephone lines but we also supplied a 2 to 4 wire hybrid in a little plastic box that had a pair of LO2567 transformers in it. The manner in which those transformers were wired was a marvel to behold!

[klangumwandler]

As previously posted, a frequency shifter will shift all frequencies additively. Thus, the spectra (overtone content) of the source will become increasingly distorted with shifting. This is opposed to say, a Harmonizer's pitch shifting. Frequency Shifters usually use a quadrature oscillator as the carrier (these were usually voltage-controlled in analog synth oriented models), and at low rates, can be used to reduce microphone feedback. The famous devices designed by Harold Bode can shift up to 5k and good carrier rejection, and were used in electronic music studios to radically alter sounds, especially sources with a lot of noise, such as percussion. FS's were featured in several analog synths, such as the Buchla, Serge (two versions, one with external carrier), and the Moog (licensed from Bode). The latter has been reissued, though I have not tried them. I've attached an image of Bode's last version.

I've contributed tracks and liner notes (specially on the FS) to a CD put together by Harold Bode's son, which will feature Bode's own home recordings and demos as well as new works using Bode's equipment. Hopefully it'll be released in the near future, I believe Robert Moog is contributing liner notes as well.

Best,

James

[Walters]

So a Frequency Shifter is just a anti feedback unit and to take out noises?


I thought a Frequency Shifter gave harmonics and added frequenecys
or crossover selective bands of frequencys and inverted some to split
and seperate them

[tINY]

Do you remember that from building FM receivers, walters. It's sorta like that.




-tINY

[Walters]

your sorta like what? tiny

[tINY]

It's a nickname - like calling a Rottweiler, "Fluffy".




-tINY

[Jonsos]

Hi peeps,

just aquired a Neve Teleconference unit quite cheap.

Obvious next question . . . does anyone know what mic pre these things have in them ? Also does anyone have a the original noddy guide on pdf or somethin' for pin outs etc ?

It certainly has an historic clutch of sockets on the back, so consequently I can't try it out yet - being clean out of 5 pin DIN plugs at the mo'

Cheerz for any replies

[Geoff_T]

Originally Posted by Jonsos

Hi peeps,

just aquired a Neve Teleconference unit quite cheap.

Obvious next question . . . does anyone know what mic pre these things have in them ? Also does anyone have a the original noddy guide on pdf or somethin' for pin outs etc ?

It certainly has an historic clutch of sockets on the back, so consequently I can't try it out yet - being clean out of 5 pin DIN plugs at the mo'

Cheerz for any replies

Hi

It's really not suitable for pro audio... the mic pre has limited band width to suit a telephone line and it connects to a 4 wire phone line.

You need two of them for a conference over a 4 wire line (or need 2 - 4 wire converters).

On its own it's a door stop.

[Jonsos]

Well, twist my nipples and call me Frank . . . .



Geoff, ta for the advice

[amino]

Frequency shifters are popular in modular synths due because of their cool effect. Here are some examples of modern frequency shifters:

Cwejman FSH-1
Encore Frequency Shifter
Doepfer A-126
Analogue Systems RS240

[chrisso]

I have a Serge Frequency Shifter.
If you mix some original audio alongside the Shifted audio you get some rich phasing effects.
If you input a melodic passage and shift the frequency so it almost mirrors the same pitch as the melody you get some ring modulator type effects, although cooler sounding.
I've also used it to literally retune drum samples. In that respect it isn't an accurate pitch shifter, but like a pitch shift with a weirder result.
Again, quite cool.

[tINY]

Originally Posted by Geoff_T

Hi

It's really not suitable for pro audio... the mic pre has limited band width to suit a telephone line and it connects to a 4 wire phone line.

You need two of them for a conference over a 4 wire line (or need 2 - 4 wire converters).

On its own it's a door stop.

It might be just the thing for blues hamonica, though....

You guys didn't include a hybrid in the "teleconferencing" unit? Wow - seems like that's the whole trick to the thing.




-tINY

[Geoff_T]

Originally Posted by tINY

It might be just the thing for blues hamonica, though....

You guys didn't include a hybrid in the "teleconferencing" unit? Wow - seems like that's the whole trick to the thing.




-tINY

Hi

Actually... he may be able to use it if he connects the send telephone output to the receive telephone input and then the mic will drive the loudspeaker (complete with frequency shift and filters) and the send and return signals may be available on the 5 pin DIN socket that you can pick up with minimal Googleing.

[Andrey]

Hello!

This recording was done in 1976.
YouTube -

I think that frequency shifter used on this record.
Tell me please, I think that's right?

Thanks in advance.
Andrew.

[sleestack]

lol, Andrew

[Andrey]

Originally Posted by sleestack

lol, Andrew

I'm sorry, I use a translator. I realized that it is ridiculous.

However, John McLaughlin 1975 album Inner Worlds, the song Miles Out.
Everywhere write that McLaughlin used the 360 systems frequency shifter with an expression pedal. The sound is very similar.

[Flying_Dutchman]

I think there was an episode in "Fringe" wasn´t it?

[timmygrimm]

Alan parsons talks about using one on the background 'oohs' on Time from DSOTM in the Classic Albums video.