HELP! How to calculate MID driver specs ?

[BuglerBass]

But who cares? Much of that unnecessary information (accurate or not) drops out entirely when you actually do the math. Throwing software (that's often marginally accurate) at a problem where you don't understand the underlying science and principles that the software "solves" depends on grasping what is and what isn't important, as well as the most important part of the solution is the real world defining of the goals based on PLAYER PREFERENCES. This is the difference between theoretical wankers and real world problem solvers, a critical differentiation of skills and ability.

Unless you have real world data of the proposed system.
Then so far this would be a pointless argument.
Not really interested in defending myself against
generalized statements.
More interested in actual data and real world design.

If he is set on 2 vertical 55 watt 4" drivers.
Be more productive to review the actual response.
And determine the actual power which they would
see.
For low level practicing some issue could be ignored.
Since the proposal includes live performance.
It would be important the system works and thermal
rating of the drivers not exceeded

 

[BuglerBass]

View attachment 5169980 View attachment 5169981 SPL.....I knew there was something I forgot to look for.
I'm thinking SPL is like the tyres on a car, If you got a huge V8 and bicycle wheels on the back you are going to use lots of power to produce heat and smoke but you ain't going nowhere.

In WinISP PRO there is SPL and MAX SPL, which one would I look at on the graphs for matching the system ?
I guess Max ISP would be at full power ? If it is then that would not have much meaning to me as I would never go that high. Its mainly for fun home stuff and I am going to make a Head cab for the Marshall 12w amp, Lab Series L4 amp and a Sunn Beta amp all the same size as the original Marshall 12w Lead Head.
I was just thinking that a Lead Stack and a Bass Stack would look good side by side.And fun.

I don't think the top cab matters that it is pointing slightly up, the stack would be about 2-1/2 feet tall with 2 speakers, and another 7" max for the head on top. (That's with feet that are 1/2" high)
If anything I might have to angle all the speakers slightly up as it's for home use.

Here are my graphs for SPL and Max SPL with my speaker versions, I think the top cab with 4 Alpha 4-4 speakers looks ok on that graph, but the 2x Alpha4-4 looks bad compared to the Kappalight 3012-4.
Any links to how to match speakers etc (For Dummies)are welcome. I want to learn as I got till next year before I can get the Kappalight 3012LF-8 I really wanted.
Blue Kappalite3012LF-4
Purple 2x Alpha4-4
Pink 4x Alpha4-4

With 4X 4ohm drivers parallel operation is not possible. Total SPL would need to be accounted
for with series/parallel operation to maintain a 4 ohm load.

For 12" LF in a reflex cab. The system unloads below cabinet Fb.
So excursion levels increase rapidly. Visible in cone excursion window.
You can apply voltage till you reach linear excursion below Fb at a feasible
lowest frequency the cabinet will receive. Then also apply power till you
reach the xlimit. This will give you a rough idea of how much power can be applied
without any over excursion filter for the linear range of the speaker and were damage
would occur.

You can also apply a over excursion filter to reduce unloading. And also review
total voltage which could be applied in linear range and mechanical limit.
Typical filter could be fourth order filter 7 to 10 Hz below Fb.

Max SPL in Winisd just applies whatever voltage you entered into the saved driver
data. Or in this case expressed as watts in winisd for the Pe tab in the driver data.
So it likely more effective to manually apply power and review cone excursion below
Fb to determine a power handling operation window.
Linear operation considered 10% distortion level which is Xmax
physical damage limit Xlim

Curious how the 4 ohm 3012LF behaves, could post a few screenshots
What volume and Fb are you using for your models?

 

[BuglerBass]

Plenty of designers choose vertical alignment

Yes correct.

Vertical alignment would be the suggested arrangement.
For Horizontal coverage.

Horizontal off axis performance and overall dispersion
would be ideal. Since majority of the listening position
on and off axis is Horizontal.

when you array drivers vertical
center to center spacing becomes rather large
and there is no way around that physically.
Which is the major tradeoff with a vertical array
since off axis vertical has major cancellations
in high frequency.

If the midrange drivers are low to the ground
or listening position is high off axis. Then majority
of the nearfield response would be extremely poor
vertical. That is the known trade-off

Only way around it would be common
crossover network which reduces high frequency
for drivers with larger center to center spacing.
Or basically the furthest drivers from the listening position.
And once you reach a feasible off axis response.
To improve directivity it would significantly lower
the crossover point of the High frequency driver.

If you just run the drivers on a common highpass
then the listening position of the midrange would
need to be at ear level. To reduce the effect
of the poor vertical off axis response. Or again
be corrected with a more refined crossover.
Which includes another set of compromises.

So basically a vertical array below the listening
position has poor directivity.
2x 6" midranges performs similar to a 12"
4x 4" midranges performs similar to 16"
off axis because of the center to center spacing.
Which again can be improved with the crossover.

 

[Wasnex]

Yes correct.

Vertical alignment would be the suggested arrangement.
For Horizontal coverage.

Horizontal off axis performance and overall dispersion
would be ideal. Since majority of the listening position
on and off axis is Horizontal.

when you array drivers vertical
center to center spacing becomes rather large
and there is no way around that physically.
Which is the major tradeoff with a vertical array
since off axis vertical has major cancellations
in high frequency.

If the midrange drivers are low to the ground
or listening position is high off axis. Then majority
of the nearfield response would be extremely poor
vertical. That is the known trade-off

Only way around it would be common
crossover network which reduces high frequency
for drivers with larger center to center spacing.
Or basically the furthest drivers from the listening position.
And once you reach a feasible off axis response.
To improve directivity it would significantly lower
the crossover point of the High frequency driver.

If you just run the drivers on a common highpass
then the listening position of the midrange would
need to be at ear level. To reduce the effect
of the poor vertical off axis response. Or again
be corrected with a more refined crossover.
Which includes another set of compromises.

So basically a vertical array below the listening
position has poor directivity.
2x 6" midranges performs similar to a 12"
4x 4" midranges performs similar to 16"
off axis because of the center to center spacing.
Which again can be improved with the crossover.

Yes I a basic understand how vertical alignment impacts dispersion. I would not use a lot of processing to compensate for off axis problems. The most I might use is a small boost that makes on-axis slightly bright, but not overly so. I generally elevate my cabs and/or tilt them back to aim at my ears.

 

[Passinwind]

Matching a midrange to a LF woofer
isn't very complicated.

Real world measurements would prove most statements
incorrect.
Vertical would be pointless in such a situation.
Not much better than a 12"

Hey @BogeyBass, how's it going?

 

[agedhorse]

I have more real world experience and successful commercial speaker designs in both pro audio and bass guitar amplification than most folks.

Much of what you are posting has little practical applications (real world) in either pro audio or bass guitar. It sounds like it’s coming from an assortment of DIY audiophile (read as audiofool) websites that historically chase rabbits down rabbit holes or sewers.

I’m beginning to wonder if you are really a chat bot troll, because the way you are posting appears to be taking bits and pieces of disjointed information from here and there and trying to make a point out of it?

 

[agedhorse]

Hey @BogeyBass, how's it going?

Another distinct possibility, in fact perhaps a more likely possibility.

 

[BuglerBass]

You proposed setting the crossover according to the
LF drivers natural roll off around 2K.
Off axis would be a huge response dip.
Since 12" directionality is much earlier than 2K.

Since baffle step and software
Seems to be considered "voodoo"
Including bunch of other disrespectful
comments from a commercial user

No need to comment much further
seems like a lost cause.
Specially if udder basic audio theory
gets deemed voodoo.

More interested in Higher quality
designs and helping people learn
how to do so. Not a generic
off the shelf item. And defending
pretty basic crossover design for
Flat response and good directionality

 

[agedhorse]

I was trying to help @Tassieviking but you came in here with your “way off on a tangent” comments that were neither helpful nor constructive.

If you understood anything about bass guitar amplification, you would recognize (or already know) the benefits and reasons for using the driver’s natural rolloff point for this application.

This is not a home audiophile DYI speaker building forum, it’s a bass guitar amplification and cabinet forum.

 

[Tassieviking]

WOW.....
I guess I should have made it clearer that this is a home build for myself (Learning Bass) and my daughter (Plays at home) and not for stage or anything like that.
This will be set up in the workshop or a bedroom or sometimes living room, nice days I might have it outside.
I am trying to build a boxcar type of speaker within my abilities so I can learn, I am not trying to make a home made Corvette as that would be way beyond my ability.

I just want a small speaker the same front dimensions as a Marshall 12watt stack since I am making some of them as well.
The front will be 14.5" x14.5", I went with 14.5" deep to give it more volume.

When I used WinISD PRO it looked like the Kappalite 3012LF was the best speaker I could get for such a tiny box, I figured I had to stuff some stuffing in to stop the sound bouncing off the walls too much, and I know my tiny vents will sound like a baked bean eating competition if the power gets cranked.
But since I am making a 500w@4ohm Lab Series L4 amp as soon as I test my PW3B-LPFv2 pedal I have just finished I thought I should try to make the cab survive the 500w @ 4ohm the few times I play it loud. ( not often).
So the main thing I am worried about is if the kappalite 3012LF will be ok in that small box even with an occasional twist of the volume knob.

Next year when the Kappalite 3012LF-8 become available I was going to get two of them and install in this setup, then I will only push 250w rms into each one.
The amp module I am installing in the L4 amp is a Chinese made class D 1000w @ 2 ohm amp and power supply, that's why I am optimistically calling it a 500w amp.(Silicon Chip magazine ran a test on several and liked this one best)
More important is what power rating would I need for the mid speakers, and the best xover frequency for me to use.
I liked the Alpha 4's purely because I could make a half cab and put 2 in, or I could put 4 in a top slant box.
I could make another square cab and put 2 Alpha 6A in it and 2 tweeters, then I would end up with a 3 stack that is chest high. (They are tiny little things).

Would this speaker be ok by itself with no mid speaker ? Or will it be too dark, I ask because I am too much of a novice myself.

I was hoping I could use the Eminence 2 way Xover set at 1k6Hz to make life simpler for me, but that would be next year when the 8 ohm speakers are available.
PX-BII 1K6 Two Way Board Only Crossover

When I learn more I will possibly make 2 fearful cabs since I will have the drivers anyway, and it's fun to do stuff like that. (Makes me feel useful since I can't work anymore, and daily medicine messes with my memory).

Thanks for all the replies, good or bad don't matter since I am learning anyway from it all.
Cheers Mick

 

[Tassieviking]

There’s an English language version of Boxsim that’s far superior to WinISD, IMO and IME

Thanks Charlie, I will check that out, if it helps me learn it will be good.
I got my daughters cheap Yamaha Bass hanging beside me and the PW3B-LPFv2 beside me as well, finished this version tonight. I will try it tomorrow and let you know.

 

[Wasnex]

@Tassieviking

Non-engineer here. The 8 ohm 3012LF is only rated for 450W RMS. Mechanical power handling is determined by the box design and is often less than the RMS rating. The 3012LF is a bit unusual in that the mechanical power handling is often much closer to the RMS rating than many other drivers. In particular the Cab Design Doc for this driver shows a small ported designed that is rated for 450W as long as you use a steep HPF set to 35hz.

I do not know if this applies to the 4 ohm variant. FYI, Eminence impedance variants of the same model don't always tune the same in the cab. In other words you may need a different tuning for 4 and 8 ohm variants of the 3012LF.

There is some (minor) differences in the response curves between the 4 and 8 ohm variant. Also the 8 ohm variant's 1W/1m Sensitivity rating is 2.6dB higher than the 4 ohm variant. The 4 ohm variant is rated for 550W RMS. You would have to run the model for your cab design to determine the mechanical power handling of the 4 ohm variant.

You can find a copy of the cab design doc here: Eminence Designer (parts-express.com)

AFAIK, the 3012LF is generally used with a mid driver. But whether this is essential depends on the type of sound you want. If it was my choice, I would go with mid drivers because I prefer more of a HiFi, full-range sound.

 

[Wasnex]

For a mid driver, it might be worth considering one of the 6s used in the Greenboy designs.

You can download designs that includes crossover circuits:
[Invalid or Expired Link Removed]

Unfortunately using a 4 ohm 3012LF invalidates the LPF on the woofer.

 

[agedhorse]

Like I mentioned before, the 4 ohm version is not a great choice, especially for that power level in such a small box.

Actually, I might recommend the 8 ohm HO version with an extended range and no tweeter for your application.

1.6kHz crossover frequency will IMO allow too much from the mid driver in the area where the level from the LF driver is already higher than I would like to see. IF there is going to be a mid bump of the LF driver, I would rather see it about an octave higher where it's less intrusive on the lower ordered harmonics of the higher strings.

 

[singlemalt]

By themselves, the LF drivers do not sound good for bass guitar. I know this because I tried it. Wooly, dark, and no definition. Seriously lacking in mids and highs.

In the right size box, they can be nice subs. With the right mid driver and crossover and cabinet design you get a winner. Call it a Greenboy fEarful. (The specs call for the 8 ohm)

The full range 3015 or 3012 do fine in a basic ported cab. Something simple like the TL 606 and the 3015 does a fine job. Easy to build with basic tools.

 

[Tassieviking]

You can find a copy of the cab design doc here: Eminence Designer (parts-express.com)

I have read those files for both the 4 ohm and 8 ohm versions, I think they are very different speakers.
I don't know if the cab designs they publish are that good since I find the small vented cab for the KL3012 4 ohm version impossible to build.
They say to make a cab with Vtotal of 1.083 cu.ft. with 2 vents @4" diameter and 16.09" long, the speaker is 12.38" in diameter so a box that's W12.38" H12.38" will have to be 12.2" deep to make 1.083cu ft.
So the cab that's just over 12" x 12" x 12" should have 2 x 4" vents 16.09" long, I just can't make that out myself but maybe I'm just not that good.

I was trying to help @Tassieviking

And I really appreciate the help from everyone, I never found the need to learn about speakers and designs in the 30 years I worked as an electrician, but I did have my instruments ratings and a few degrees in electronics as most of my work involved large DC and AC drives and all the crap linking up to a few dozen drives to sync up.
I even got to work with project involving fighter jets which was different for me, looking back I had some fun while working.

Anyway, here are the specs for the KL3012LF 4 and 8 ohm versions in case someone wants to look.

 

[Passinwind]

I have read those files for both the 4 ohm and 8 ohm versions, I think they are very different speakers.
I don't know if the cab designs they publish are that good since I find the small vented cab for the KL3012 4 ohm version impossible to build.
They say to make a cab with Vtotal of 1.083 cu.ft. with 2 vents @4" diameter and 16.09" long, the speaker is 12.38" in diameter so a box that's W12.38" H12.38" will have to be 12.2" deep to make 1.083cu ft.
So the cab that's just over 12" x 12" x 12" should have 2 x 4" vents 16.09" long, I just can't make that out myself but maybe I'm just not that good.

The vents don't necessarily have to be one straight piece, if that helps any.

 

[HaphAsSard]

They say to make a cab with Vtotal of 1.083 cu.ft. with 2 vents @4" diameter and 16.09" long, the speaker is 12.38" in diameter so a box that's W12.38" H12.38" will have to be 12.2" deep to make 1.083cu ft.
So the cab that's just over 12" x 12" x 12" should have 2 x 4" vents 16.09" long, I just can't make that out myself but maybe I'm just not that good.

The driver alone displaces 1.5 litres, and the two vents about 8.25; I agree that a design with conventionally placed ports (baffle or back) couldn't accommodate the entire length of the tubes, with enough clearance between their inner openings and the opposite panel, without the volume being necessarily larger than 30 lts, but one with side or top vents might. I came up with ca 33*51*25 cm (inside) dimensions, but haven't had time to re-check my math nor identify possible kinks.

 

[agedhorse]

This is a good reason why we choose a driver suitable to the enclosure goals rather than trying to design an enclosure around a driver that may not be appropriate or the goals. Then, adjust, adapt and compromise.

This is also why getting too deep into the weeds on insignificant details doesn’t matter, there are plenty of more important things that are impacting the performance of the design.

I would recommend looking at a DeltaLite 2512-8 in a simple ported box, you may not need anything else. It tuned ok in a smaller box of around 1.25 cubic feet.

 

[Tassieviking]

I think I have a lot to think over, but I should be getting the Kappalite 3012LF-4 late this week so I think that construction grade ply very cheap so I can play around with a deeper cab to add more volume and just experiment.
If I like what I hear I can build it in marine ply later, marine ply is what I can get locally, its heavier but very sturdy.
I think I will get an Alpha6A and see if it will be ok with the Kappalite.
I don't have a test speaker for the bench or any bass speaker at all right now, so I will definitely make something in the near future for myself.

So just to confirm, no-one thinks my little speaker box will be ok with a Kappalite 3012LF-8 in it ?
I would make a second cab with a mid and maybe a horn in it, I could use the same speakers as the fEarful 12-6 and even the same Xover.
Please note it will be for personal use at home, and it does not have to be as good as a Corvette, I would be building a billy-cart of a speaker. (Everyone has to start somewhere).

I might have to start with some GreenBacks and build some lead cabs in the Marshall 12w stack size.

Cheers
Mick.