rickcr42
Are YOU talkin' to me?
- Joined
- Jun 21, 2001
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History of surround sound as I remember it
1-the original David Hafler (dynaco) passive ambience extraction system.Use a simple box hooked up to the main speakers which extracted a L-R difference signal from the normal L and R main signal.All it did was wire L rear - and R rear - to the L front + and R front +.Both rear speaker + together.
did not work with all recordings but when it did it sounded great.There actually were some recordings made back then with an added L-R ambience channel.
2-Quadraphonics/4 Channel/SQ/QS/Vario Logic/Etc.Lasted about four years or so and never really took off.Really just a line level electronic version of the original "Dynaquad" circuit above.In fact the hafler device was touted as a poor mans 4 CH decoder.The recording engineers never really knew what to do with the extra two channels so results were inconsistant
3-Audio Delay Lines.Made by Advent,Audiopulse,benchmark,etc.
What these had was a variable delay of from 20 to 100 ms to the rear speakers .Some operated on a straight feed to the rear speakers and this was called ambience extraction.Some used a L-R delayed signal (like the dynaquad again) and this was called ambience extraction.
In the three areas above it can be seen that the consistant is the original David Hafler L-R "Dynaquad" ambience extraction circuit.Alone or in front of a delay line it produced the most natural results IF there was some out of phase material on the recording itself.In other words,nothing added but extracted from the original performance.This difference signal is available from any live performance or a studio performance done in one take and not over processed.Results are not good with overdubbed and over processed artifically put together performances.Sometimes delay could be used in the "ambience Synthesis " method to add a "live" feeling to the playback,but it was pleasing at its best and artificial sounding at its worst,especially when one tried to use the "stadium" setting on the delay (full delay of 100ms or more and total reverb which is the signal fed back to the opposite channnel and re-delayed) with totally overdubbed Rock.The was also a "cathedral" setting with an insane 200ms delay ! Nothing but echo.
And that brings us to
4-Dolby Surround Sound.Some genious came up with the idea of taking the original hafler L-R signal and adding a fixed 25 to 30 ms delay to that and marketing it NOT as a music reproduction device but a "Home Theater" device.Finally there was a standard which engineers could encode to and rather than being aimed at the "audiophile" it was marketed at "everyman".After all,who does not watch movies ?
And it worked,bottom line.An extra channel of L-R or REAR information could be added that did NOTHING to the front channels so the system would be compatible with any system,and easily upgraded by adding an additional stereo amp with speaker pair.
Another smart move was to make the claim that the rear speakers did not have to be as good as the front pair (a cost saving) due to the Bandwidth limited nature of the surround channels (somewhere around 100hz to 7khz)
Next were added features such as stereo synthesis,music settings,etc.
But still,for music not the best choice
5-Dolby Pro Logic.As above but with the addition of logic "steering" circuitry for emphasis of a signal and a sub woofer channel.
Now even though it is called five channels or %.1 it is really still a two channel system with L+R mixed for the center channel ,L-R delayed for the rear channels (its is really a mono signal run to two speakers" and a low pass filter to add a subwoofer,again,not a discrete channel.
So nothing is really new here,just a new use of the original 1960s technology with some delay thrown in but targeted at the mainstream consumer
So what do I use ?
Wel the 5X100 WATT Dolby PRO LOGIC Pioneer receiver is retired !
It never really was up to quality music reproduction,even in the stereo mode and I always found Dolby Prologic to sound a bit "croaky" for lack of a better word.But it was 'in system" for about two years.Then I found a device that just seemed right .For a couple of years there was a device marketed by the "new" Dynaco called the "QD-1 Series ll Five Channel Home Theater System".
The original DYNAQUAD with the addition of a center channel output and volume controls !!!!
ONE SINGLE STEREO AMPLIFIER !
THREE MORE SPEAKERS (which I already had for my dolby system)
YESSSS !!!!!!!!!
Being a passive device means it in NO WAY touches the front signal,the integrity of the system is left intact.Especially if used in the manner I use it.Instead of running my front channels "through" the device I run a feed from my power amp directly to my main peaker system,normal operation.This connection is made to the binding post in the normal manner.
The QD-1 is then hooked into the system by taking a second set of speaker cables and with banana plugs inserted into the binding posts "stacking" the connections.
From the QD-1 are the rear and center channel speaker connections.
I used this for a while and it sounds WAY more natural ,due to the totally passive nature and nothing added approach .
But being passive meant signal loss.
Signal attenuation of the rear channels is a good thing ,you never play the "effects" channel as loud as the main channel anyway.
But the center or "dialog" channel needs to be at or near the volume level of the main left and right speaker systems.
What to do ?
My first thought was to purchase a center channel speaker system with a higher sensitivity rating,thus it would play louder with the same amount of power.But that would mean my five channels would no longer be matched systems.
Instead I came up with a solution that in my case proved to be ideal.
I added a passive resistor network to the speaker level center channel output of the QD-1 that dropped the signal to a line level signal.I then used an old Dynaco singl channel tube power amp to supply the power for the dialog channel.
Did it work ?
All I can say is .my surround system is done.I am totally satisfied.
When playing movies it is all five channels.
With music it is either two or four (never five,center sounds.......),depends on the recording.
But ALL sound good,noothing between my source and speakers but preamp/power amp.
But what about headphones ?
Well you remember those early Audio Delay Lines ?
I just happen to have one.An Audiopulse Model 2.
I put together a simple op-amp L-R matrix with a capacitor as the low cut of 100 hz and an RC network as the high cut of 7khz in front of the audiopulse,one channel only, and a simple op-amp mixer on the output.
I then split the original stereo signal which then goes
1-to the mixer untouched
2-to the mixer after being processed as above
The mixer then goes to my headphone amp .
SO DAMN SIMPLE !
I tried in various ways to implement the dialog,or L+R channel but it never really sounded right .Instead I use a crossfeed circuit to blend things a bit .
How does it sound ?
Works for me
This went a bit long but since I have not been around here too much lately I figured I would put a weeks worht in one post
1-the original David Hafler (dynaco) passive ambience extraction system.Use a simple box hooked up to the main speakers which extracted a L-R difference signal from the normal L and R main signal.All it did was wire L rear - and R rear - to the L front + and R front +.Both rear speaker + together.
did not work with all recordings but when it did it sounded great.There actually were some recordings made back then with an added L-R ambience channel.
2-Quadraphonics/4 Channel/SQ/QS/Vario Logic/Etc.Lasted about four years or so and never really took off.Really just a line level electronic version of the original "Dynaquad" circuit above.In fact the hafler device was touted as a poor mans 4 CH decoder.The recording engineers never really knew what to do with the extra two channels so results were inconsistant
3-Audio Delay Lines.Made by Advent,Audiopulse,benchmark,etc.
What these had was a variable delay of from 20 to 100 ms to the rear speakers .Some operated on a straight feed to the rear speakers and this was called ambience extraction.Some used a L-R delayed signal (like the dynaquad again) and this was called ambience extraction.
In the three areas above it can be seen that the consistant is the original David Hafler L-R "Dynaquad" ambience extraction circuit.Alone or in front of a delay line it produced the most natural results IF there was some out of phase material on the recording itself.In other words,nothing added but extracted from the original performance.This difference signal is available from any live performance or a studio performance done in one take and not over processed.Results are not good with overdubbed and over processed artifically put together performances.Sometimes delay could be used in the "ambience Synthesis " method to add a "live" feeling to the playback,but it was pleasing at its best and artificial sounding at its worst,especially when one tried to use the "stadium" setting on the delay (full delay of 100ms or more and total reverb which is the signal fed back to the opposite channnel and re-delayed) with totally overdubbed Rock.The was also a "cathedral" setting with an insane 200ms delay ! Nothing but echo.
And that brings us to
4-Dolby Surround Sound.Some genious came up with the idea of taking the original hafler L-R signal and adding a fixed 25 to 30 ms delay to that and marketing it NOT as a music reproduction device but a "Home Theater" device.Finally there was a standard which engineers could encode to and rather than being aimed at the "audiophile" it was marketed at "everyman".After all,who does not watch movies ?
And it worked,bottom line.An extra channel of L-R or REAR information could be added that did NOTHING to the front channels so the system would be compatible with any system,and easily upgraded by adding an additional stereo amp with speaker pair.
Another smart move was to make the claim that the rear speakers did not have to be as good as the front pair (a cost saving) due to the Bandwidth limited nature of the surround channels (somewhere around 100hz to 7khz)
Next were added features such as stereo synthesis,music settings,etc.
But still,for music not the best choice
5-Dolby Pro Logic.As above but with the addition of logic "steering" circuitry for emphasis of a signal and a sub woofer channel.
Now even though it is called five channels or %.1 it is really still a two channel system with L+R mixed for the center channel ,L-R delayed for the rear channels (its is really a mono signal run to two speakers" and a low pass filter to add a subwoofer,again,not a discrete channel.
So nothing is really new here,just a new use of the original 1960s technology with some delay thrown in but targeted at the mainstream consumer
So what do I use ?
Wel the 5X100 WATT Dolby PRO LOGIC Pioneer receiver is retired !
It never really was up to quality music reproduction,even in the stereo mode and I always found Dolby Prologic to sound a bit "croaky" for lack of a better word.But it was 'in system" for about two years.Then I found a device that just seemed right .For a couple of years there was a device marketed by the "new" Dynaco called the "QD-1 Series ll Five Channel Home Theater System".
The original DYNAQUAD with the addition of a center channel output and volume controls !!!!
ONE SINGLE STEREO AMPLIFIER !
THREE MORE SPEAKERS (which I already had for my dolby system)
YESSSS !!!!!!!!!
Being a passive device means it in NO WAY touches the front signal,the integrity of the system is left intact.Especially if used in the manner I use it.Instead of running my front channels "through" the device I run a feed from my power amp directly to my main peaker system,normal operation.This connection is made to the binding post in the normal manner.
The QD-1 is then hooked into the system by taking a second set of speaker cables and with banana plugs inserted into the binding posts "stacking" the connections.
From the QD-1 are the rear and center channel speaker connections.
I used this for a while and it sounds WAY more natural ,due to the totally passive nature and nothing added approach .
But being passive meant signal loss.
Signal attenuation of the rear channels is a good thing ,you never play the "effects" channel as loud as the main channel anyway.
But the center or "dialog" channel needs to be at or near the volume level of the main left and right speaker systems.
What to do ?
My first thought was to purchase a center channel speaker system with a higher sensitivity rating,thus it would play louder with the same amount of power.But that would mean my five channels would no longer be matched systems.
Instead I came up with a solution that in my case proved to be ideal.
I added a passive resistor network to the speaker level center channel output of the QD-1 that dropped the signal to a line level signal.I then used an old Dynaco singl channel tube power amp to supply the power for the dialog channel.
Did it work ?
All I can say is .my surround system is done.I am totally satisfied.
When playing movies it is all five channels.
With music it is either two or four (never five,center sounds.......),depends on the recording.
But ALL sound good,noothing between my source and speakers but preamp/power amp.
But what about headphones ?
Well you remember those early Audio Delay Lines ?
I just happen to have one.An Audiopulse Model 2.
I put together a simple op-amp L-R matrix with a capacitor as the low cut of 100 hz and an RC network as the high cut of 7khz in front of the audiopulse,one channel only, and a simple op-amp mixer on the output.
I then split the original stereo signal which then goes
1-to the mixer untouched
2-to the mixer after being processed as above
The mixer then goes to my headphone amp .
SO DAMN SIMPLE !
I tried in various ways to implement the dialog,or L+R channel but it never really sounded right .Instead I use a crossfeed circuit to blend things a bit .
How does it sound ?
Works for me
This went a bit long but since I have not been around here too much lately I figured I would put a weeks worht in one post
