$325 Lab 12 based PA tapped horn ~ 35Hz extension

[m R g S r]

Max SPL 1 cabinet, 500 watt input (46.3V into 4.29 ohms)

2 Series 2 Parallel Speakers, 4.29ohm amplifier load, 2000watts (92.6V):

 

[m R g S r]

Is Hornresp lying about the bottom end? Who knows. But if not, a little crown xti 2000, 4 of these $325 cabinets, some EQ, 136db down to around 35hz....sounds like a party! For cheap too!

 

[tb46]

Hi m R g S r,

Are boards I/H/F connected w/ right angles?

Regards,

 

[m R g S r]

Yes the are

 

[tb46]

Thanks. Just want to point out that you don't need a 4-section Hornresp model if you have a constant expansion angle in the path. (Back to work!)

Regards,

 

[weltersys]

Bad news, can't fit it all on one 4x8 sheet. So I most likely won't waste $ on two 4x8 MDF sheets, ill just build the test cabinet from (2) 3/4" Baltic Birch sheets and hope it works out!

Not really bad news, MDF is not as stiff, and would show less upper response than Baltic Birch, so the finished response would have been different than the prototype.

 

[m R g S r]

Ordered the cabinet hardware, will get the wood this week and get started on the construction / testing....

 

[tb46]

Hi Y'all,

Just a quick question, would the LAB12 be rugged enough to handle 3:1 compression ratio?

Regards,

 

[m R g S r]

The cone I'm sure it can. It's strong. The motor? I don't know. Never tried it. Maybe at low power, but at higher power it might choke.

 

[tb46]

Is there any way of simulating this (motor choking)?

Regards,

 

[m R g S r]

Not that I know of. I don't know if the motor will actually stall in place, but it might sound not so great
This is just guessing, I'm not positive on this, sorry I can't help more.

 

[weltersys]

Hi Y'all,

Just a quick question, would the LAB12 be rugged enough to handle 3:1 compression ratio?

3/1 should not be a problem for the Lab 12, it worked fine in the Keystone at about 2.5 to one, and the LabHorn and 12Pi are around 2.62/1. The only mechanical cone problems I have heard of in Labhorns have been traced to leaking compression chambers.

I don't know what mSgR means by "motor choking", the Lab 12 certainly has plenty of power compression from voice coil heating, but Bl is Bl, it has a strong motor that pushes hard up till past Xmax until the voice coil is hot.

Thermal, rather than mechanical limitations are the Lab 12s weak link.

 

[m R g S r]

Got started on the build!
I got a lot less done than I expected today (my only afternoon off this week) because I cleaned the workshop, but at least I have more room in there now!

Most of the pieces have the final cuts completed, just a few boards need the angle cuts.

Here is what I accomplished today:

 

[m R g S r]

Got a little more work done this morning before work this afternoon....

 

[m R g S r]

Little more

An externally hosted image should be here but it was not working when we last tested it.

 

[epa]

looks good
are you using 18mm?

 

[tb46]

Hi mRgSr,

Yes, looks good. Are you sure you've got enough screws in there?

Regards,

 

[m R g S r]

Haha thanks. Yeah I did screws every 50mm. Not necessary I know but figured it wouldn't hurt.

The wood is all 18mm Baltic birch.
My new supplier sells it for $55 after tax per sheet. That's the best price I've found, with no minimum quantity!

 

[tb46]

Hi,

That's a great price for BB, is that for 5'x5'?

Regards,

 

[m R g S r]

Yup! 5x5. 1/2" is dirt cheap, like $33 per 5x5 I believe.
I am going to build some compact 2x15" midbasses to accompany this pair of PAL12 horns, and ill be using the 1/2". So ill let you know a final price on that in a few weeks.

Ill Inquire about shipping costs, if you buy in bulk it might offset the shippi h cost and be worth it for you to order from them!