HELP! How to calculate MID driver specs ?

[Tassieviking]

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.

I just worked the Deltalite out in my box, if that is 1.25cu ft before the driver and vent goes in it makes it smaller then my cab, I would have to reduce the depth by 23mm or 15/16".
Surely that would not be the volume without the driver or vent in there ?

My box is about 38.1 litres or 1.345 cu ft without driver or vent, and I could make it deeper or shorter to suit a driver.

 

[Arjank]

All four
View attachment 5170547

Nice stack

 

[agedhorse]

I just worked the Deltalite out in my box, if that is 1.25cu ft before the driver and vent goes in it makes it smaller then my cab, I would have to reduce the depth by 23mm or 15/16".
Surely that would not be the volume without the driver or vent in there ?

My box is about 38.1 litres or 1.345 cu ft without driver or vent, and I could make it deeper or shorter to suit a driver.

Correct, your existing box would be fine, the port area needs to be a little smaller so the port length decreases to a shorter, more reasonable length.

 

[Tassieviking]

If anyone else wants to try to work out the low/mid/high power ratio for each driver I would recommend reading this article by Rod Elliott :Passive Crossover Network Design
There is even a simple graph that shows the low pass / high pass power ratio for each driver.
Cheers
Mick

 

[Doufuss]

If anyone else wants to try to work out the low/mid/high power ratio for each driver I would recommend reading this article by Rod Elliott :Passive Crossover Network Design
There is even a simple graph that shows the low pass / high pass power ratio for each driver.
Cheers
Mick

If I understand you correctly, the 4 ohm 3012LF is enroute? If so, you have to work with what you have in hand. I don't know about the 4 ohm driver, but the 8 ohm model seems to be happy in a 2-ish cubic foot box tuned to around 45 Hz.

As has been stated above, the LF is a dark sounding speaker and really more suitable as a true woofer than a bass guitar speaker. However, there are workarounds, such as the excellent 12-6 Fearful and a design from Quilter labs that uses the BGH 25-8 tweeter that sounds good with the 3012LF.

The Fearful crossover design won't work with the 4 ohm 30121LF, so you'll have to figure that out. But the Quilter design might, where the woofer is run full range and the tweeter is first order high passed at around 3500 Hz. You will have to pad this tweeter significantly, say on the order of 10db, to get them to play nice with each other.

There are a number of internet sites purporting to be 'the' crossover experts out there and you can find yourself chasing your tail or worse, damaging your amplifier with a complicated crossover scheme. Keep it simple, and the parts robust.

Good luck with your project and please let us know how you make out.

 

[agedhorse]

There are indeed crossover designers that produce crossover designs that are called “amp killers” in the industry. They are based on an absurd mystique rather than an understanding of amplifiers and the resulting speaker loads.

 

[Tassieviking]

If I understand you correctly, the 4 ohm 3012LF is enroute?

I have the KL3012LF-4 now, it was the last KL3012LF available in Australia when I bought it and the 8 ohm ones will not be available until sometime in the 1st half of 2024 down here.
I grabbed it because there were no others available.
I got 2 x Alphalite6A speakers this week and I will get some more gear so when the KL3012-8 speakers are available I can build a pair off fearful 12/6 speakers.

This current build is just for fun to make pair of useful speakers that will match the 12w Marshal Bass amp I made. I am making 2 speakers so it will look like a mini Marshall stack.
It will be fun and give me some more experience making cabs and head shells before I go at the fearfuls later next year.

 

[agedhorse]

How about a 1.5 cubic foot enclosure with (2) 3" ducts, what would be a sensible length port for the 2512 in that case?

Maybe.