Stereo 4

Stereo-4 is a small trick to enlarge the stereo-field.

It works like this.

The front speakers are just ordinary stereo, but the additional (rear) speakers) they couple with the amplifier using e few resistors, which cause that the "stereo" signal (the difference between L-R) is stronger than the signal L+R which comens from both speakers at the same time.
This was also called "spatial stereo"

It added some dimension, specially in small deep living rooms.

But it was a quite simple trick, nothing special ans surely NOT for the real HiFi lover.

In fact, Radio Shack or Tandy sold a box these days to create the same effect, and they put a wirewound slide resistor in it so that you could regulate it.

The REAL thing in the seventies was Quadro. For that systems were special recordings, and that was the first real multichannel sound system.

The previous comment may need a little bit more detail...

Spatial stereo was a means to widen the stereo image through normal 2 channel systems, like many manufacturers did and do up to this day. One of the more advanced techniques is for example the Q-Sound technology which (not only) Philips used on its soundcards (Acoustic Edge). If you want to hear Q-Sound in action you can try Roger Waters' "Amused To Death" CD. Horrible music but ultra wide stereo effects coming from far left and right. In fact unbelievable.

The stereo-4 trick is basically just sending the difference between the L and R channels to rear speakers. Since the L and R channels are normally a little different (because of the stereo nature) you will have some resulting signal. Depending on the source material you either hear nothing (in the case of mono source) to a lot (stereo with loads of differences between the channels)

You can accomplish that yourself easily by connecting 1 or 2 rear speakers (in series) between the +L and +R red speaker terminals. That may look like a dangerous experiment but it isnt.

In my younger days (around 1980) I had such a setup (with a DUX 2in1 system) and I remember it sounded actually very good. If I compare that to the relative disappointment of recent experiments I did with multichannel SACD and DVD-Audio I think still the stereo-4 trick might be a quick solution to add a nice "surround" feel to your system.

regards

Basemaster

In the philips stereo-4 setup there was no connection between +R and +L terminal but they made an resistor network that caused stereo on the rear speakers with more differantial signal.
The trick above just keeps you ONLY the L-R signal, which may sound weird.

indeed there was a knob to control the "weirdness" of the rear signal, I guess it was based on the L-R signal anyway, with some additional stuff I dont exactly know.

L-R sounds weird of course but as a rear signal my experience was it sounds quite good to enhance your stereo system.

Yeah, i did also some testing with this long time ago. I once saw the schematic diagram of such an amplifier in those days.

What is also a nice experiment is to put the difference signal on an additional center speaker 😉

Hi

Thanks for your replies, I can understand what is stereo4 now

@Mic_hifi wrote:

Hi

Thanks for your replies, I can understand what is stereo4 now

Nice collection

Thanks i found all my collection here in france in flea markets near where i m living, i m quite lucky.
It all started with the 22RH882 but now i m looking for a bandrecorder to complete my set, do you have any idea of which one is the best for my collection ?

The next step will be the quadriphonie and/or mfb.

A have two more questions

* for my 22rh520 Versterkers, what is the best set for the spaekers ? the 22rh423 for the front and the 22ah492 for the rear?

* what is different between the ceramic cristal and hificeramic dynamic sound ?

Thanks for your helps.

it is better to use 4 identical speakers if you use stereo-4 or quadraphonic systems.

the ceramic or cristal input is suitable for older phono cartridges. the hifi ceramic/dynamic is for use with magnetodynamic phono cartridges of very good ceramic cartridges.