I think your plan to add a new tweeter atop the Winslow is a logical step. But l am scratching my head on your implementation.
I recommend testing a tweeter on the Winslow but bear in mind my prior illustration of the ATC mid domes off axis performance relative to a flat front plate tweeter and a wave guide mounted tweeter.
You need to be really mindful of what any changes mean in a particular situation.
Otherwise you end up with links and dips in your precious off axis response lines which will earn you loathing feedback from your esteemed objectivist friends. They will listen with their eyes before their ears while perspiration drips down your brow.
To avoid this agonising predicament we must once again look at the facts.
But first a primer.
In what ever you decide to do a comparison will only be meaningful if in fact the chosen tweeter tracks the off axis lines of the ATC dome. Or alternatively the ATC dome tracks the MD60 Satori dome or a tweeter.
Confused? Read on…
This means looking at the off axis tracking through the crossover region and relative to the pass band of the mid dome and the tweeter.
In more detail the term CD or constant directivity isn’t a standard set in stone. It means even off axis lines across the frequency spectrum starting at the transition from the woofer to a horn or a dome tweeter from 700-1000 hertz through to 7,000 hertz.
This is assessed after normalising the on axis response to flat.
The idea is to have flat level lines in the 0, 10, 20, 30 range left and right and up and down. This is normally the listening window. Beyond that smooth lines are preferred. Above 7000 hertz a smooth level set of lines is not necessarily a desirable criteria.
The subjective result could be brightness or a recession in certain aspects of the presentation. This has the effect of impacting on the overall tonal balance when the direct and off axis sound sums at the listening position. The other impact is that sound stage can also become disproportionate in some frequency regions.
So you need to approach constant directivity with a degree of precision.
With a multi way system this is easier said than done. Hence horn loaded wave guides and wave guides on tweeters are becoming popular for those who hold CD - constant direction in high esteem.
In the table below l have set out the matrix of drivers discussed as a measurement of off axis level relative to on axis at 3kertz.
30 degree off axis tracking
2.5K. 3K. 3.5K. 4K. 4.5K
18WU4741. -3. -4. -4. -7. -9
MD 60. -1.5. -2. -3. -3.5. -4.5
ATC mid. -2.5. -3.5 -4.0 -4.5 -5
Tweeter
3004/606. 0.0. +1.5 +1. -1.5. -1
Wave guide
SB26STW -1. -1.5 -2. -2.5. -3
Scan mid
12MU4731. -1. -2. -2. -3. -4
Looking at the above results my pick of any pairing is as follows. Ranked in degree of difficulty to implement easiest to hard work.
trend Simple solution as both drivers
have designed in diffraction and CD
3. 18WU4741+MD60+SB26STW
150 hertz - 800 hertz in 17L for B2
sealed , cross to MD60 800 & 3,800 hz
Cross mid dual woofers with
independent low pass crossover filters.
Complex and difficult to implement.
2. 12MU4731+ SB26STW crossover
3.5Khertz, 18WU4741 crossover 350
hertz, delete 70 hertz HP filter
Comment. Both track closely relatively
A good combo with a discrete narrow
band mid bass woofers 70-350 hertz
Less complex than No 3 as the single
Mid driver operates 350-3.5 khertz
Dual 8 inch sealed mid mass woofers
require only one low pass cross over @
350 hertz. 12 db HP Bessel Transfer
function will does not require an
active high pass filter
an active HP filter @ 70 hertz for
music reproduction.
I recommend testing a tweeter on the Winslow but bear in mind my prior illustration of the ATC mid domes off axis performance relative to a flat front plate tweeter and a wave guide mounted tweeter.
You need to be really mindful of what any changes mean in a particular situation.
Otherwise you end up with links and dips in your precious off axis response lines which will earn you loathing feedback from your esteemed objectivist friends. They will listen with their eyes before their ears while perspiration drips down your brow.
To avoid this agonising predicament we must once again look at the facts.
But first a primer.
In what ever you decide to do a comparison will only be meaningful if in fact the chosen tweeter tracks the off axis lines of the ATC dome. Or alternatively the ATC dome tracks the MD60 Satori dome or a tweeter.
Confused? Read on…
This means looking at the off axis tracking through the crossover region and relative to the pass band of the mid dome and the tweeter.
In more detail the term CD or constant directivity isn’t a standard set in stone. It means even off axis lines across the frequency spectrum starting at the transition from the woofer to a horn or a dome tweeter from 700-1000 hertz through to 7,000 hertz.
This is assessed after normalising the on axis response to flat.
The idea is to have flat level lines in the 0, 10, 20, 30 range left and right and up and down. This is normally the listening window. Beyond that smooth lines are preferred. Above 7000 hertz a smooth level set of lines is not necessarily a desirable criteria.
The subjective result could be brightness or a recession in certain aspects of the presentation. This has the effect of impacting on the overall tonal balance when the direct and off axis sound sums at the listening position. The other impact is that sound stage can also become disproportionate in some frequency regions.
So you need to approach constant directivity with a degree of precision.
With a multi way system this is easier said than done. Hence horn loaded wave guides and wave guides on tweeters are becoming popular for those who hold CD - constant direction in high esteem.
In the table below l have set out the matrix of drivers discussed as a measurement of off axis level relative to on axis at 3kertz.
30 degree off axis tracking
2.5K. 3K. 3.5K. 4K. 4.5K
18WU4741. -3. -4. -4. -7. -9
MD 60. -1.5. -2. -3. -3.5. -4.5
ATC mid. -2.5. -3.5 -4.0 -4.5 -5
Tweeter
3004/606. 0.0. +1.5 +1. -1.5. -1
Wave guide
SB26STW -1. -1.5 -2. -2.5. -3
Scan mid
12MU4731. -1. -2. -2. -3. -4
Looking at the above results my pick of any pairing is as follows. Ranked in degree of difficulty to implement easiest to hard work.
- ATC mid + SB26STW crossover 3Khertz
trend Simple solution as both drivers
have designed in diffraction and CD
3. 18WU4741+MD60+SB26STW
150 hertz - 800 hertz in 17L for B2
sealed , cross to MD60 800 & 3,800 hz
Cross mid dual woofers with
independent low pass crossover filters.
Complex and difficult to implement.
2. 12MU4731+ SB26STW crossover
3.5Khertz, 18WU4741 crossover 350
hertz, delete 70 hertz HP filter
Comment. Both track closely relatively
A good combo with a discrete narrow
band mid bass woofers 70-350 hertz
Less complex than No 3 as the single
Mid driver operates 350-3.5 khertz
Dual 8 inch sealed mid mass woofers
require only one low pass cross over @
350 hertz. 12 db HP Bessel Transfer
function will does not require an
active high pass filter
an active HP filter @ 70 hertz for
music reproduction.
Attachments
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A question(s)for the owner
How many feet do you sit from the Winslow system?
How far out is the front baffle from the front wall?
What is the distance from your listening position to the rear wall?
How far is the left and right loudspeaker from each side wall?
I re read your previous post on your experiences with room correction and the affirmative feedback from your friends.
Can you describe how you went above getting the Winslow system to perform to the point it is now?
What have you discovered along the way?
Looking at the attached sketch how have you located your listening position?
How many feet do you sit from the Winslow system?
How far out is the front baffle from the front wall?
What is the distance from your listening position to the rear wall?
How far is the left and right loudspeaker from each side wall?
I re read your previous post on your experiences with room correction and the affirmative feedback from your friends.
Can you describe how you went above getting the Winslow system to perform to the point it is now?
What have you discovered along the way?
Looking at the attached sketch how have you located your listening position?
Attachments
Last edited: