KM2

[Anti K]

Found something interesting from JBL Pro list. TS parameters cause in result in enclosures at certain area parallel phase shifts.
Low plus Mid.


Did it just happened to me or are the drivers designed like this, don’t know.


Can somebody say by own experience:
If for example at crossover point two drivers are phase coherent, then bend phase graphs absolutely parallel is not possible. OK.
How many degrees phase shift off from octave higher/lower region, is listenable/acceptable (subjective opinion).
I got some 4-5degrees off, if go octave lower or higher from crosspoint.
24db/oct I think will use.

Cross Low/Mid at 300Hz, adjusting delay 0,12ms they will be at crosspoint right (not neccessary mention the 180degree 'trick')

[pos]

Hey, you specifically removed the part about transconductance in your quote
Too bad, this is one of the big positives of using a midwoofer.

Regarding crossover design and phase tracking, do not try to overthink this in advance based on T/S parameters or published measurement: this will never work in practice.
You will need to measure with the driver in place, and adjust/build the crossover there.
This will not be easy, perhaps the most difficult part of your journey, but there is no way around it so be prepared.

[Anti K]

Hey, you specifically removed the part about transconductance in your quote
Too bad, this is one of the big positives of using a midwoofer.

Trying find drivers first (potential candidates)

Are really TS parameters so different (JBL ones) on paper and in reality, even while cabinet planning ?

[Ian Mackenzie]

No.

[pos]

The official T/S are pretty accurate, but outside of modeling LF response to design a box, T/S are pretty limited in use, and certainly not sufficient to design a crossover for example.

[Ian Mackenzie]

Trying find drivers first (potential candidates)

Are really TS parameters so different (JBL ones) on paper and in reality, even while cabinet planning ?

This is not your thinking yet but a dual concentric driver would solve some of your searching for drivers.


Most people when they think of dual concentric think of a Tannoy or an Altec 604. But today a number of pro loudspeaker manufacturers incl JBL previously make this kind of driver.

The benefit to you is a number of decisions are made for you. The implementation is simplified considerably.

They come in 6, 8, 10, 12 and 15 inch size with a high frequency compression driver mounted on the rear of the woofer magnet. The high frequency horn is mounted though the centre of the woofer magnet.

Radian make Be versions. Other manufacturers make them and Great Plains Audio make versions of Altec 12 and 16 inch dual concentric drivers.

The simple way to use then is in an enclosure on top of your Everest cabinets

The thing is they are almost a point source and some have an internal passive crossover network.

This approach could be a starting point as you evolve your project.

At this point you seem wedded to the reincarnation of the Everest cabinets. However, it does lock you in and limits your flexibility in terms of what drivers and horn or wave guide you choose and how you want to set them up. This also includes the crossover functionality which is significantly impacted by the physical location of the drivers. What works and doesn’t work can be somewhat unpredictable.

Separate test boxes stacked on top of each other for the purpose of trying different ideas would move you to the important try, pass, fail of different options much earlier. You could then focus on how to use the Everest cabinets.

The idea is get the acoustic concept right before you tackle the industrial design.

This path could avoid disappointments, frustration, time lost and expense.

[Mr. Widget]

Separate test boxes stacked on top of each other for the purpose of trying different ideas would move you to the important try, pass, fail of different options much earlier. You could then focus on how to use the Everest cabinets.

The idea is get the acoustic concept right before you tackle the industrial design.

This path could avoid disappointments, frustration, time lost and expense.

+1

This is how I have approached all of my bigger projects... and I still have been pounded into reality check moments and had to go back to the drawing board.

Since you want to design something new and at a high performance level, anything less would be very risky.


Widget

[Ian Mackenzie]

The novelty of looking for expensive drivers soon wears off after you spend your money.

[Ian Mackenzie]

Found something interesting from JBL Pro list. TS parameters cause in result in enclosures at certain area parallel phase shifts.
Low plus Mid.


Did it just happened to me or are the drivers designed like this, don’t know.


Can somebody say by own experience:
If for example at crossover point two drivers are phase coherent, then bend phase graphs absolutely parallel is not possible. OK.
How many degrees phase shift off from octave higher/lower region, is listenable/acceptable (subjective opinion).
I got some 4-5degrees off, if go octave lower or higher from crosspoint.
24db/oct I think will use.

Cross Low/Mid at 300Hz, adjusting delay 0,12ms they will be at crosspoint right (not neccessary mention the 180degree 'trick')

Yeah but it’s misleading.

All drivers are Pass band devices and there phase will shift at either side of the pass band. The only reliable way is to measure the response and do a minimum phase transformation function
from the FR.

Ideally you want to crossover at the lower end before significant phase shift occurs but this is not always possible.

The crossover will typically be a minimum 12 dB slope at the lowest crossover point and this created two 90 degree phase angles at the crossover point. The LR sum flat with the phase revered electrically, BW do not. The LW 4th order sum flat.

This assumes the drivers are text book and your acoustic centre ( usually the voice coil) are in alignment vertically. Don’t loose sleep over this right now as their are ways to add phase compensation without physical alignment. Physically alignment should only be considered if the horn throat and the cone driver are close (+-25mm) as this can cause big response irregularities in the mid and high frequencies and completely mask the otherwise high resolution of your drivers.

[Ian Mackenzie]

You mentioned (l think something about crossover ranges).

Nice drivers are the foundation but how you use them and more to the point how well they work with each other is important.

Possible options

Bass 250-300,
Mid high1200-1500,
Uhf 8000-10,000 hertz.

That’s not written in stone. lt depends on the drivers power handling, displacement Xmax at two octaves below the crossover point, cone break up and directivity as you have commented. The distance between the centres of your divers also needs to be considered.

While the above is a rule of thumb your room and your listening preferences also factor into the configuration.

Let’s play a game and make a few reasonable assumptions
Your room is unfurnished and has large flat surfaces
The ceiling is high but the floor had no covering
You will sit 3-6 metres from the system.

My first decision would be to get the bass right as with classical music you want really good bass definition and you want high dynamic range. You don’t need subterranean bass.

The dual 2216nd will give reserve headroom.
Limit the low frequency limit to 30 hertz at this stage so a sub does not cloud your thoughts.
See if you can put the woofers in vertically? This can be less problematic than dual horizontal woofers in some situations.

The crossover point could be 250 - 500 hertz.
With 250 hertz crossover your mid needs to be able to handle a lot of power and to two octaves below the crossover point so if you want 250 hertz think about a 12 inch driver. But there are trade offs.

But that limits the horn crossover point to 1000-1200 hertz.
The horn profile will be like 12-14 inches and it will extend some way behind the baffle.
If you find a nice Jbl Diff drive 8 inch driver consider a 400 hertz crossover point and you can crossover up to 1500-2000 hertz. An 8 inch cone is going to be smoother and perhaps warmer than a compromised horn at lower crossover frequencies due to baffle constraints. The lower you go the horn had to be much larger not to compromise sound quality. It’s just how it is.

The benefit is you have paper direct radiators through a large portion of the midrange without any nasty horn issues. Cones are a lot more diy friendly than compression drivers and horns and they often sound better to those who appreciate the classic genre.

A crossover point of 1500-2200 hertz gives you more options with wave guides or horns or a direct radiator. There areless crossover point issues as the horn profile is much smaller and not as deep. This allows the use of cones with a shallower cone profile. This also frees up your options for placement of the mid cone and the horn. Jbl do this in their consumer systems.

This is the thing. You are more likely to achieve a coherent sound from a small tightly packed mid high frequency array than a large one. It’s just how it is. You don’t need really loud PA levels above the first crossover point with your listening style and listening relatively close to the loudspeakers. The room is going to be live when those curtains are drawn and a smooth modest sound level will suffice and be more enjoyable. If you decide on a larger cone mid and as a consequence the horn will be larger you will need to sit further back. But the further back you listen the more of your rooms bad effect will be heard as a larger ratio of indirect versus direct sound.

You will need to play around with the listening location but aim for 2.5-3.00 or 3.5 - 5.00 metres equilateral triangle loudspeaker and listening position. It will definitely image with about 10-15 degrees toe in of the enclosure.

A 10 or an 8 inch mid (not a mid bass like the 2661H) is going to top 100 dB sensitivity. You won’t use much power there with a 360-500 hertz 24 dB crossover point.

Jbl make a of the smaller few rectangle pro versions of the M2 wave guide which Rob has had success with. A 90 x 90 or a 90 x 60 horn or wave guide may work better than a 100 x 100 wave guide in your room.

You could easily swap out the horn / wave guide for a nice dome mid or a Heil ATM like a Mundorf. Beyma make those too in a horn loaded form. Radian make an excellent BE and AL one inch driver.

I hope this makes sense and assists with your project.

[Anti K]

I would have to have eyes on to tell whether they could be brought to a proper quality of finish. Anti has said that he is thinking in terms of a A+++ paint finish. Nothing wrong with that.

Some good and positive responses here fellahs

Painted finish is actually a technical decision (but I like it very much too )
Current veneer has heavy scraches in some places and need a new layer anyway.
But also, have to mess up with epoxy and sanding to integrate parts seamlessly together, so...

Will see which part white and which black, gloss or matte. Painting is flexible in terms of experimenting.
One thing is clear - Ferrary-red of dramatic-blue they will NOT be. I'm a conservative avant-garde

[Anti K]

Reminds me of something I posted a while back...These threads can go on and on

At least something funny aside these lockdowns and stuff , isn't it?

24db/oct I think

Yeah but it’s misleading. The LW 4th order sum flat.

24dB/oct (LR of cause) vs LW 4th order
!?
pros and cons of 24dB/oct Linkwitz–Riley and 4th order Linkwitz–Riley

Most people when they think of dual concentric

DID I ???

/… / today a number of pro loudspeaker manufacturers incl JBL previously make this kind of driver.
/… / 6, 8, 10, 12 and 15 inch size with a high frequency compression driver mounted on the rear of the woofer magnet.

Coaxials?
I messed up with these in past, SEAS ones, exxel ones, Beyma ones.
How it’s…
… this is a idea! Two 15inch COXes (probably Vintage Beyma with some 44mm pig-killing-voice CDs) into holes of Everest cabinets.
Higher part of cab - between the lips - is ideal for tubes. Maybe one oval tube between lips!
It would look really cool! Like a new Honda Civic butt.
NEVEREST (N=new + Everest)


Now is my turn to ask You same question You asked from me: ‘where are You located?’
Are we on the same side of our flat planet?
Btw, I got BionTec with these chips inside and already stood 5 minutes below the 5G pole as well - downloaded new upgrades, feels good.

[Anti K]

Separate test boxes…

+1
This is how I have approached all of my bigger projects...

I’ll do that, Mr. Widget.
That’s why I’m doind my math simulations (not to get final and right, but to get which side to go).
That’s the reason the cabs still stay as they are - didnt kick the saw in there yet.
Have not intention kill these nice cabs and later scrach my head how to put these pieces together

At moment I try to make the Lens section. It’s hard part in terms of building, woodwork, finishing. Actually, prepare how to finish that part. It stays on sight….
Trying go with with this part until I’m satisfied what I see.


After that: a ‘15minutes-work’ kick into some clumsy-ugly boxes the Mids. What I already choosed from JBL Pro gear list and for now ordered as well.
And math simulation plans for (clumsy boxes) is part of this.
If it all doesn’t work, will see what next.
At moment I just wait for parts across the Atlantic…

But I bet it has to be a damn good reason avoid JBL new DD cones with these insanely rigid baskets, which are in same time heatsinks.
You are one of these few people who closely looked at the room plan and understands what I’m talking about

[Anti K]

You mentioned (l think something about crossover ranges).

Nice drivers are the foundation but how you use them and more to the point how well they work with each other is important.

Possible options

Bass 250-300,
Mid high1200-1500,
Uhf 8000-10,000 hertz.

That’s not written in stone. lt depends on the drivers power handling, displacement Xmax at two octaves below the crossover point, cone break up and directivity as you have commented. The distance between the centres of your divers also needs to be considered.

While the above is a rule of thumb your room and your listening preferences also factor into the configuration.

Let’s play a game and make a few reasonable assumptions
Your room is unfurnished and has large flat surfaces
The ceiling is high but the floor had no covering
You will sit 3-6 metres from the system.

My first decision would be to get the bass right as with classical music you want really good bass definition and you want high dynamic range. You don’t need subterranean bass.

The dual 2216nd will give reserve headroom.
Limit the low frequency limit to 30 hertz at this stage so a sub does not cloud your thoughts.
See if you can put the woofers in vertically? This can be less problematic than dual horizontal woofers in some situations.

The crossover point could be 250 - 500 hertz.
With 250 hertz crossover your mid needs to be able to handle a lot of power and to two octaves below the crossover point so if you want 250 hertz think about a 12 inch driver. But there are trade offs.

But that limits the horn crossover point to 1000-1200 hertz.
The horn profile will be like 12-14 inches and it will extend some way behind the baffle.
If you find a nice Jbl Diff drive 8 inch driver consider a 400 hertz crossover point and you can crossover up to 1500-2000 hertz. An 8 inch cone is going to be smoother and perhaps warmer than a compromised horn at lower crossover frequencies due to baffle constraints. The lower you go the horn had to be much larger not to compromise sound quality. It’s just how it is.

The benefit is you have paper direct radiators through a large portion of the midrange without any nasty horn issues. Cones are a lot more diy friendly than compression drivers and horns and they often sound better to those who appreciate the classic genre.

A crossover point of 1500-2200 hertz gives you more options with wave guides or horns or a direct radiator. There areless crossover point issues as the horn profile is much smaller and not as deep. This allows the use of cones with a shallower cone profile. This also frees up your options for placement of the mid cone and the horn. Jbl do this in their consumer systems.

This is the thing. You are more likely to achieve a coherent sound from a small tightly packed mid high frequency array than a large one. It’s just how it is. You don’t need really loud PA levels above the first crossover point with your listening style and listening relatively close to the loudspeakers. The room is going to be live when those curtains are drawn and a smooth modest sound level will suffice and be more enjoyable. If you decide on a larger cone mid and as a consequence the horn will be larger you will need to sit further back. But the further back you listen the more of your rooms bad effect will be heard as a larger ratio of indirect versus direct sound.

You will need to play around with the listening location but aim for 2.5-3.00 or 3.5 - 5.00 metres equilateral triangle loudspeaker and listening position. It will definitely image with about 10-15 degrees toe in of the enclosure.

A 10 or an 8 inch mid (not a mid bass like the 2661H) is going to top 100 dB sensitivity. You won’t use much power there with a 360-500 hertz 24 dB crossover point.

Jbl make a of the smaller few rectangle pro versions of the M2 wave guide which Rob has had success with. A 90 x 90 or a 90 x 60 horn or wave guide may work better than a 100 x 100 wave guide in your room.

You could easily swap out the horn / wave guide for a nice dome mid or a Heil ATM like a Mundorf. Beyma make those too in a horn loaded form. Radian make an excellent BE and AL one inch driver.

I hope this makes sense and assists with your project.

Sure:

[Ian Mackenzie]

It’s the most sensible post you’ve made to date. I can actually understand it.