dynaquad diamond

[Quadrobineg]

i know that the "diamond" setup has no relevance, but how would its encoding matrix look like? it can´t be the same as for Lf Rf Lr Rr, right?

 

[par4ken]

i know that the "diamond" setup has no relevance, but how would its encoding matrix look like? it can´t be the same as for Lf Rf Lr Rr, right?

No corner speakers just L, R, Cf, and Cb. The diamond pattern was later altered to the more familiar four corner configuration. There is at least one demo record for the diamond pattern Dynaco set up. I was going to post pictures but will have to dig out the album first. There is a thread or at least some posts here about it as well.

The "rock" track although uncredited is actually the group Steam, known for "Na Na Hey Hey Kiss Him Goodbye". The track is (if I remember correctly) "Love And Affection".

Here is the Discogs release link. The release year 1973 has got to be wrong! More likely about 1970.

https://www.discogs.com/release/1875327-Unknown-Artist-4-Dimensional-Sound-Demonstration

​

 

[par4ken]

Here are the Dynaco posts from several years ago.

The Steam track was actually "I’m Gotta Make you Love Me".

https://www.quadraphonicquad.com/fo...n-track-listings-here.8470/page-3#post-101866

 

[Quadrobineg]

so there is actually 1 or 2 pieces using it, interesting.

but of course a listening example doesnt tell much about the encoding scheme.

for now i simply sum the dynaquad encoders´ channels to get the "diamond" ones, it seems to be the only thing what makes sense.

but here is another suggestion, which seems unreasoned (including his proposal for the square)...

https://www.quadraphonicquad.com/fo...d-encoder-info-appreciated.29444/#post-529882
...and i cant find a source for it.

 

[par4ken]

The Dynaco "diamond" was just regular stereo with an out of phase signal added for Cb. So obvious encode equations would be as follows.

Lt = L + .707 Cf + .707 Cb
Rt = R + .707 Cf - .707 Cb

However the tones on my test record showed Cb was a bit lower in level, perhaps to compensate for the fact that with the passive decode system the the front speaker is in series with the L and R speakers which will reduce its level making the back speaker sound too loud. So the equation would be more like the following.

Lt = L + .707 Cf + .5 Cb
Rt = R + .707 Cf - .5 Cb

Edit: Checking the Dynaco 4-D Demonstration record it is the back speaker vocal announcement that is a bit louder than that of the front. As there are no actual test tones of a set level that we can verify, so we are safe to assume the the first set of coefficients' is correct. It makes sense that the front and rear be encoded signals be the same level and 3dB down from the left and right. I assume that the announcer was just speaking a bit louder into the microphone with the back announcement.

Also Discogs says the record is from 1973, which can not be correct. It is more likely from 1970, 1971 at the very latest.

 

[Quadrobineg]

but that is completely different from the square matrix of the same name?

the square system also has different matrixes for encoding and decoding, which might be the reason why you see this difference in weighting.

i am in the progress of revamping some of my 20 years old software and eventually i should actually let check you guys if i did those stupid encoders right. i already found errors in one of them (i did not figure that you need to set the phase to relative-zero also for inputs which are not sent to multiple channels. i found that out by noticing that this is what you also have to do for pro logic. there, it is a logical consequence of the matrix, while missing in the instructions.)

the math for all these encoders should be simple (except for the dolby B dynamics, but i dont include that anyway), but you should know that i have no idea how their microphone setups looked in the 70ies.

and yes, i am aware that they skipped the diamond nonsense quickly, but i guess if it "existed" i want to include it in my experiments, and then it should be done "right".

 

[par4ken]

It has to be different as you are encoding two back signals instead of one. Also you want the encoded signal to be compatible with stereo playback, you can't just rotate the diamond, to get four corners. The Dynaco and ElectroVoice were very similar/close. The encode and decode coefficients were determined subjectively. They are asymmetrical to give better subjective results without using any form of logic enhancement.

 

[Quadrobineg]

i feel like an aercheologist, wikipedia still has no information for me about the magic diamond, just as 20 years ago.

the stereo compatibility! is a major reasoning which i totally missed until now. (it is not like we would require that today for distributing digital music, but of course if it is part of the specs i should not ignore it)

in the current "version" i just "rotated the soundfield" of the square decoder, which is

Lt = L 1.0 + R 0. + Lb 0.64 - Rb 0.36

to

Ls = (L 1.0 + R 0.)/2 + (R 0. + Lb 0.64)/2 + (Lb 0.64 + Rb -0.36)/2 + (Rb -0.36 + L 1.0)/2

due to lack of description it seemed to be the most logical thing to do.^^

 

[Sonik Wiz]

i feel like an aercheologist, wikipedia still has no information for me about the magic diamond, just as 20 years ago.

the stereo compatibility! is a major reasoning which i totally missed until now. (it is not like we would require that today for distributing digital music, but of course if it is part of the specs i should not ignore it)

in the current "version" i just "rotated the soundfield" of the square decoder, which is

Lt = L 1.0 + R 0. + Lb 0.64 - Rb 0.36

to

Ls = (L 1.0 + R 0.)/2 + (R 0. + Lb 0.64)/2 + (Lb 0.64 + Rb -0.36)/2 + (Rb -0.36 + L 1.0)/2

due to lack of description it seemed to be the most logical thing to do.^^

On the forum front page there's a section called QQ Links. It's easy to over look if you just check out What's New but certainly it is worth looking over. Forum member @MidiMagic has link there. It takes you to this:

https://midimagic.sgc-hosting.com/quadindx.htm
Be sure to see Quadraphonic Systems in Detail. It might be what you're looking for.

 

[kfbkfb]

https://worldradiohistory.com/Archive-All-Audio/Archive-Audio/70s/Audio-1970-07.pdf#page=22
(article by David Hafler of Dynaco)


Kirk Bayne

 

[MidiMagic]

I have the record. Here is the listing.

I also have a copy of the Perrey-Kingsley Flight o9f the Bumblebee on their album without the 4D encoding.

That Discogs link is not the same record.

 

[MidiMagic]

i know that the "diamond" setup has no relevance, but how would its encoding matrix look like? it can´t be the same as for Lf Rf Lr Rr, right?

I am tired of everyone looking at where the speakers are and thinking that the encoding equations must match the speaker locations. With the RM system, one encoder works just fine with a different decoder. This is not true with SQ or discrete.

It has to be different as you are encoding two back signals instead of one. Also you want the encoded signal to be compatible with stereo playback, you can't just rotate the diamond, to get four corners. The Dynaco and ElectroVoice were very similar/close. The encode and decode coefficients were determined subjectively. They are asymmetrical to give better subjective results without using any form of logic enhancement.

I use exactly the same encoder to make a recording that plays the same on Hafler Diamond, Dynaquad, Electro Voice Stereo-4, Scheiber, Sansui QS, Dolby Surround, Dolby Pro Logic I and II, and Surround Master QS. That's because the overall RM system is the same for all of them.

This setup can be used for live music or recording. Connect the recorder to the mix out.

The encoder insert and the encoded vectors (as on a phono record) are below. The encoder goes in the bus inserts for buses 3 and 4.

Here is a diagram of how to encode each direction:

If you encode with this, your pan positions will be the same on any of the decoders I listed earlier.

 

[MidiMagic]

Above are two circuits for the Hafler Diamond. The blend control for the one on the left is at the amplifier inputs. The right one uses speakers with RCA cables. They use any RM matrix.

Below is a hexaphonic decoder that uses 6 speakers. It also work with any RM matrix.

 

[par4ken]

I have the record. Here is the listing.

View attachment 89472

I also have a copy of the Perrey-Kingsley Flight o9f the Bumblebee on their album without the 4D encoding.

That Discogs link is not the same record.

That is not the "diamond" Dynaco record that we are talking about it is this one.
https://www.discogs.com/release/1875327-Unknown-Artist-4-Dimensional-Sound-Demonstration

 

[MidiMagic]

That is not the "diamond" Dynaco record that we are talking about it is this one.
https://www.discogs.com/release/1875327-Unknown-Artist-4-Dimensional-Sound-Demonstration

But it works equally well on the diamond and on the Dynaquad.
....
With one difference: no cogging using the diamond speaker layout.

I have never seen nor heard of that record. I probably would have bought it if I had. And it would work equally well with all of the systems I listed too.

 

[par4ken]

But it works equally well on the diamond and on the Dynaquad.
....
With one difference: no cogging using the diamond speaker layout.

I have never seen nor heard of that record. I probably would have bought it if I had. And it would work equally well w3ith all of the systems I listed too.

Yes no cogging because you have speakers at the sides, you can get the same effect with the square layout if you simply move the rear speakers forward to the sides.

 

[Quadrobineg]

I am tired of everyone looking at where the speakers are and thinking that the encoding equations must match the speaker locations.

actually i was more looking at its name.

when there are 2 things called "dynaquad" and only one of them is documented publicy and the other one not, i thought it could be a good idea to just use the same encoder for it and average the speakers.

I use exactly the same encoder to make a recording that plays the same on Hafler Diamond, Dynaquad, Electro Voice Stereo-4, Scheiber, Sansui QS, Dolby Surround, and Dolby Pro Logic I and II. That's because the overall RM system is the same for all of them.

i am not at the stage where i use my encoders myself. after i´ve build them for the first time i rather invented my own system and went away from matrixes.

but my future researches might go into exactly that direction: how to organize mixes so that they work with different decoders. it is of course a completly different topic than encoding a 4:2: master.

however, as a musician, the free positioning of virtual sound sources is important for me, and as most quadrophonic systems have weaknesses at the one or other side, the best option to support 4 speakers for me personally would be to do a binaural downmix to 4 channels and provide 4 discrete channels to the listener.

on the contrary it could be quite fun to try to support all these vintage formats as they are, and create 2 channels CD media for you people with your old analog decoders.

 

[MidiMagic]

It could be a good idea to just use the same encoder for it and average the speakers.


on the contrary it could be quite fun to try to support all these vintage formats as they are, and create 2 channels CD media for you people with your old analog decoders.

The systems I listed are so cl;ose to each other in how they work that the same encoder can make a recording that decodes correctly on all of them.

 

[ar surround]

For me, DynaQuad was the rabbit hole that got me into all of this multichannel absurdity. It is dirt cheap in its most basic implementation and highly effective. But now instead of four speakers, I've got twelve...DynaDozen.

 

[Quadrobineg]

The systems I listed are so cl;ose to each other in how they work that the same encoder can make a recording that decodes correctly on all of them.

would that still be correct when we change the conditions as follows: mono- and stereo compatibilty is not required and our mixes are done likewise.

(for example, as i mentioned, when i want to use the 4:2 encoding mainly for easy distribution and it can contain binaural rendered content already, so that we use the 4 speakers to have full 360 degree positioning, which is not possible when you use these formats as intended.)