If you do, please be sure to make and publish accurate measurements of the transient response, and more importantly IMO the attack / decay through the circuit. I have a suspision the attack/decay is where such a circuit would really show degeneration, materializing as a 'muddying' of the sound.DorinD said:
Hi,
four observations but no solutions.
1. is the speed of sound in the horn the same as or different to sound in free air? or, to ask the question another way is the required delay to match the distance difference i.e. (340m/s)/path difference (m)? Is it something to do with pressure wave to velocity wave?
2. can you delay by the equivalent of 600mm (2ft) and retain quality?
3. can you physically move the drivers/horns to achieve actual sound path equality? no electronics required!
4. does bass phase being delayed by the physically longer path matter?
four observations but no solutions.
1. is the speed of sound in the horn the same as or different to sound in free air? or, to ask the question another way is the required delay to match the distance difference i.e. (340m/s)/path difference (m)? Is it something to do with pressure wave to velocity wave?
2. can you delay by the equivalent of 600mm (2ft) and retain quality?
3. can you physically move the drivers/horns to achieve actual sound path equality? no electronics required!
4. does bass phase being delayed by the physically longer path matter?
"1. is the speed of sound in the horn the same as or different to sound in free air? or, to ask the question another way is the required delay to match the distance difference i.e. (340m/s)/path difference (m)? Is it something to do with pressure wave to velocity wave?"
Same
"2. can you delay by the equivalent of 600mm (2ft) and retain quality?"
Not with that many capacitors in the circuit
"3. can you physically move the drivers/horns to achieve actual sound path equality? no electronics required!"
No
"4. does bass phase being delayed by the physically longer path matter?"
Yes, the transient response will be a lot better, and the perceived 'depth' of the music will improve.
In the mid 30s the movie industry realized what an improvement reducing the time delay between drivers could do. Despite being in the depth of the Great Depression they spent the money to develope and upgrade systems.
A new standard of zero path length difference was then developed, but WWII delayed the upgrade until after the war.
The instruction set for time alignment of the later system requires reversing the phase of the HF, then moving the HF horn back and forth for the greatest null, then restoring correct phase. A difference of an inch or two is measureable in the depth of the null (this distance is obviously variable with the crossover frequency, the higher the frequency the less offset is acceptable).
Comparing an aligned system with an un-alligned one generally produces comments on the order of 'how could I ever have listened to it without alignment'. This presumes the crossover and delay are of sufficient high quality as to not 'fog' all the detail. Inexpensive pro sound components will require upgrades for people with better associated equipment.
Same
"2. can you delay by the equivalent of 600mm (2ft) and retain quality?"
Not with that many capacitors in the circuit
"3. can you physically move the drivers/horns to achieve actual sound path equality? no electronics required!"
No
"4. does bass phase being delayed by the physically longer path matter?"
Yes, the transient response will be a lot better, and the perceived 'depth' of the music will improve.
In the mid 30s the movie industry realized what an improvement reducing the time delay between drivers could do. Despite being in the depth of the Great Depression they spent the money to develope and upgrade systems.
A new standard of zero path length difference was then developed, but WWII delayed the upgrade until after the war.
The instruction set for time alignment of the later system requires reversing the phase of the HF, then moving the HF horn back and forth for the greatest null, then restoring correct phase. A difference of an inch or two is measureable in the depth of the null (this distance is obviously variable with the crossover frequency, the higher the frequency the less offset is acceptable).
Comparing an aligned system with an un-alligned one generally produces comments on the order of 'how could I ever have listened to it without alignment'. This presumes the crossover and delay are of sufficient high quality as to not 'fog' all the detail. Inexpensive pro sound components will require upgrades for people with better associated equipment.
"how can you answer for M8o? What does the speaker set-up look like?"
From the first post:
"[Klipsch La Scala]."
"If it were possible to physically align the centres, would there be no need for an electronic delay nor for any phase reversal?"
At the risck of repeating myself:
"A new standard of zero path length difference was then developed"
"The instruction set for time alignment of the later system requires reversing the phase of the HF, then moving the HF horn back and forth for the greatest null, then restoring correct phase. "
And we still do a phase reversal to check ourselves.
From the first post:
"[Klipsch La Scala]."
"If it were possible to physically align the centres, would there be no need for an electronic delay nor for any phase reversal?"
At the risck of repeating myself:
"A new standard of zero path length difference was then developed"
"The instruction set for time alignment of the later system requires reversing the phase of the HF, then moving the HF horn back and forth for the greatest null, then restoring correct phase. "
And we still do a phase reversal to check ourselves.
Though I may be more 'verbose' sometimes providing supporting explaination, djk did answer as I would so I won't go over them again.
The problem just trying to do physcal time alignment would be the tweeter would be sitting at the very back end of a 2ft deep, 4++ sq.ft. plane (the top of the speaker cabinet), with -all- the sound radiating below the tweeter's center plane bouncing off the top of the cabinet. Just not an option I'd take, even if someone decided to give me all the sound deadening material I wanted for free to try to control that ... (will anyone? <grin> we know the answer.)
As it currently is, I calculate that the tweeter is operating just below the level of group delay that is said to be "perceptable" at the 4.5K crossover freq. Having worked with my Terrasonde Audio Toolbox 3 in my Jeep to time align the bass, to front speakers, to rear speakers, I know what time alignment can do to the clarity of the picture the audio reproduction paints when properly aligned.
The problem just trying to do physcal time alignment would be the tweeter would be sitting at the very back end of a 2ft deep, 4++ sq.ft. plane (the top of the speaker cabinet), with -all- the sound radiating below the tweeter's center plane bouncing off the top of the cabinet. Just not an option I'd take, even if someone decided to give me all the sound deadening material I wanted for free to try to control that ... (will anyone? <grin> we know the answer.)
As it currently is, I calculate that the tweeter is operating just below the level of group delay that is said to be "perceptable" at the 4.5K crossover freq. Having worked with my Terrasonde Audio Toolbox 3 in my Jeep to time align the bass, to front speakers, to rear speakers, I know what time alignment can do to the clarity of the picture the audio reproduction paints when properly aligned.
Hmmm.... This unit is analog, but it had 0 - 2ms delay.
http://www.parts-express.com/pe/pshowdetl.cfm?Partnumber=248-668
I wonder if they'll tell me how if I ask them. (I'm also considering the Behringer digital x-over too)
...edit, oh, crud, ignore that.
It says "controls the delay on the low output". ... ok, we all know that's 'relatively' easy. it's delay on the 'high' output that I need, and that is 'hard'.
OK, back to digital...
http://www.parts-express.com/pe/pshowdetl.cfm?Partnumber=248-668
I wonder if they'll tell me how if I ask them. (I'm also considering the Behringer digital x-over too)
...edit, oh, crud, ignore that.
It says "controls the delay on the low output". ... ok, we all know that's 'relatively' easy. it's delay on the 'high' output that I need, and that is 'hard'.OK, back to digital...
A cheap toy to play some "analog" delaying. They said it used some "vintage" BBD's:
http://www.behringer.com/VD400/index.cfm?lang=ENG
or even
http://www.behringer.com/VM1/index.cfm?lang=ENG
or some pure digital ones:
http://www.behringer.com/DD400/index.cfm?lang=ENG
http://www.behringer.com/DD100/index.cfm?lang=ENG
They are very cheep (35-45euros/2channel) and virtualy easy to mod for pure delay-ing.
http://www.behringer.com/VD400/index.cfm?lang=ENG
or even
http://www.behringer.com/VM1/index.cfm?lang=ENG
or some pure digital ones:
http://www.behringer.com/DD400/index.cfm?lang=ENG
http://www.behringer.com/DD100/index.cfm?lang=ENG
They are very cheep (35-45euros/2channel) and virtualy easy to mod for pure delay-ing.
a new digital processor option...
To bring back-up a thread that's been very helpful to me....
Regarding another digital processor made for live sound that can serve as a digital x-over .... Does anyone have experience with the BSS PS-8810 processor?
http://www.bssaudious.com/includes/product_sheet_include.aspx?product_id=32
If any do, would you say it's suitable for use in a 'quiet' media room? Forgive my use of the word, but does it have 'audiophile' sound quality? Or is it just suitable for 'live sound' where it's made for, where a much higher level of noise and distortion is acceptable? i.e., I'm wondering is it 'Behringer-like' or much higher end?
I know someone who is selling some but I can't find any discussion about it out on the 'net. The list price is many thousand, but there seems to be a bunch selling on eBay for a small fraction of list. That's 'odd' IMO; I'm worried it is instead 'telling' as to quality as well.
To bring back-up a thread that's been very helpful to me....
Regarding another digital processor made for live sound that can serve as a digital x-over .... Does anyone have experience with the BSS PS-8810 processor?
http://www.bssaudious.com/includes/product_sheet_include.aspx?product_id=32
If any do, would you say it's suitable for use in a 'quiet' media room? Forgive my use of the word, but does it have 'audiophile' sound quality? Or is it just suitable for 'live sound' where it's made for, where a much higher level of noise and distortion is acceptable? i.e., I'm wondering is it 'Behringer-like' or much higher end?
I know someone who is selling some but I can't find any discussion about it out on the 'net. The list price is many thousand, but there seems to be a bunch selling on eBay for a small fraction of list. That's 'odd' IMO; I'm worried it is instead 'telling' as to quality as well.
For the purpose of archiving my journey ... Just thought I'd mention for anyone that happens upon this thread that I ended up purchasing the BSS prosys unit linked to above for a great price. Check out the operator's manual; capabilities of it are staggering. I imagine I'll only use perhaps less then 10% of it tho. I'm keeping my fingers crossed that noise floor and A/D/A conversion proves to be 'HiFi'.
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