Old hand made JBL musical instrument cabinets

[maxserg]

Hi everybody I'm new to this forum.

Question:

I have a pair of K-145 and a pair of 2420 drivers collecting the dust. For the mid-high, I have a McCaully horn/lens(about 8 to 9 inches wide) and another set of JBL "folded lens" of about 21 inches wide. The concept would to get the most from theese drivers to have hi-fi sound for my house playback music and film stereo playback. I already have boxes made from JBL's plans (back from the 70's) the boxes have around 3,5 cu Feet, that is too big for my living room.

I would prefer hi-fi sound (maybe forget about horns and just put the 2420 directly on a plate for a tweeter or use econowave waveguide for the 2420 16 ohms)use the 2420 from 1K to 20K, I know that the passive JBL Xover is made for 800Hz split. Ideas are welcome.

My Xover is from JBL(passive) at 800Hz. I just find that the efficiency ot the 2420 is too high for the K145(even at maximum attenuation). I know that I could pad it a few db's but this another question.

So the goal is to have a friendly box that is not too big. I don't want to have freezer-like bok in me living room.

The goal is not expensive built and good power in house!

Active or passive???

Any suggestion are welcome.

Forgot to say that the K145 is 8 Ohms

[jcrobso]

Hi everybody I'm new to this forum.

Question:

I have a pair of K-145 and a pair of 2420 drivers collecting the dust. For the mid-high, I have a McCaully horn/lens(about 8 to 9 inches wide) and another set of JBL "folded lens" of about 21 inches wide. The concept would to get the most from theese drivers to have hi-fi sound for my house playback music and film stereo playback. I already have boxes made from JBL's plans (back from the 70's) the boxes have around 3,5 cu Feet, that is too big for my living room.

I would prefer hi-fi sound (maybe forget about horns and just put the 2420 directly on a plate for a tweeter or use econowave waveguide for the 2420 16 ohms)use the 2420 from 1K to 20K, I know that the passive JBL Xover is made for 800Hz split. Ideas are welcome.

My Xover is from JBL(passive) at 800Hz. I just find that the efficiency ot the 2420 is too high for the K145(even at maximum attenuation). I know that I could pad it a few db's but this another question.

So the goal is to have a friendly box that is not too big. I don't want to have freezer-like box in me living room.

The goal is not expensive built and good power in house!

Active or passive???

Any suggestion are welcome.

Forgot to say that the K145 is 8 Ohms
Welcome to the forum!

3.5 cu ft. is the minim that is needed for the K145, that is just the way it is. You could build a little bit smaller box, but you will lose bass response.
You didn't list the model # of the crossover. But I'm guessing that it has a switch for the HF attenuation rather than a L-pad, if so you could still put a L-pad between the crossover and the 2420. The Mc Caully horn/lens would probably be better if you want to keep the appearance small.
You have some very good, but BIG speakers and they are difficult to put in a small box.

[maxserg]

Welcome to the forum!

3.5 cu ft. is the minim that is needed for the K145, that is just the way it is. You could build a little bit smaller box, but you will lose bass response.
You didn't list the model # of the crossover. But I'm guessing that it has a switch for the HF attenuation rather than a L-pad, if so you could still put a L-pad between the crossover and the 2420. The Mc Caully horn/lens would probably be better if you want to keep the appearance small.
You have some very good, but BIG speakers and they are difficult to put in a small box.

For the Xover yes it is a 3 steps attenuator

[maxserg]

Sorry I pushed the quote button an what I see is that my post is on the top fo the thread:o:

[maxserg]

I want to have a electronic Xover for this beast unless I have a passive Xover that someone would bring in...:o:

[Zilch]

2344(A) horn and 16-Ohm version of L200t3 crossover:

http://www.audioheritage.org/vbulletin/showthread.php?p=71276#post71276

Looks like it played "hot" in the VHF 4.5 years ago, though.

Active's no panacea, because you still have to work out the high-frequency compensation for whatever horn you use.

Can it be done with DCX2496? Yes, but you'll have to be able to measure the response to get it dialed in optimally.

How about the Parham HF comp approach? Yes, but somebody with measurement capability would have to work it out.

PT waveguide and throat adapter? Yes, maybe, but 1 kHz is a "push," and 3110's 800 Hz is almost certainly too low.

4430 crossover? Yes, with 2344(A) horns and 8-Ohm diaphragms installed in the 2420s.

2370A? Maybe, but somebody would have to finesse it into submission.

811 or 511? Yes, if you don't mind them beaming the VHF.

Smith horn or 3-way? Not my job, man.... :p

[maxserg]

2344(A) horn and 16-Ohm version of L200t3 crossover:

http://www.audioheritage.org/vbulletin/showthread.php?p=71276#post71276

Looks like it played "hot" in the VHF 4.5 years ago, though.

Active's no panacea, because you still have to work out the high-frequency compensation for whatever horn you use.

Can it be done with DCX2496? Yes, but you'll have to be able to measure the response to get it dialed in optimally.

How about the Parham HF comp approach? Yes, but somebody with measurement capability would have to work it out.

PT waveguide and throat adapter? Yes, maybe, but 1 kHz is a "push," and 3110's 800 Hz is almost certainly too low.

4430 crossover? Yes, with 2344(A) horns and 8-Ohm diaphragms installed in the 2420s.

2370A? Maybe, but somebody would have to finesse it into submission.

811 or 511? Yes, if you don't mind them beaming the VHF.

Smith horn or 3-way? Not my job, man.... :p

Thanks Zilch

For measurement purpose I have a pair of Neumann KM184(matched pair), for audio interface I can use my Digidesign MBox. For Mac software I dunno if there is a freeware (Mac OSX 10,4) but I gueess that I have apropriate hardware.

For what I read the econowave waveguide would make my 2420 smoother and I think I have enough efficiency spare for the hf section even with a passive xover. But why I would go active is that I already have enough amps (Crown DC-300A and D-150A) so I just have to buy the DCX2496 and with the apropriate software, it could be easier to fine-tune it.

Your opinion?

[Zilch]

Fuzzmeasure is a measurement software package for Mac, I believe. You'll need a true measurement microphone like the $50 Behringer ECM8000. They require phantom power; verify that your Designbox has that.... :yes:

[grumpy]

Fuzzmeasure and 10.4.x? You'd have to use an old version:

http://supermegaultragroovy.com/products/FuzzMeasure2/

As a demo ... I don't recall the limitations.

K184? cardioid recording mics... if you realize they drop off below 100Hz
and have a broad peak at 9KHz they could still be useful, but only if you
understand their limitations (might help in setting crossover frequency
and matching driver levels, but you'd be adding a layer of difficulty in
interpreting much more).

http://www.neumann.com/zoom.php?zoomimg=./assets/diagrams/s180_diagrams.htm&zoomlabel=Diagram&w=878&h=278

Don't expect miracles from the K145 in a small box. Appears that 3ft3
will get you to ~60Hz before roll off.

[maxserg]

Fuzzmeasure is a measurement software package for Mac, I believe. You'll need a true measurement microphone like the $50 Behringer ECM8000. They require phantom power; verify that your Designbox has that.... :yes:

Ok I can buy the Brehinger measurement mike.

The MBox has switchable phantom (48volts):)

[maxserg]

Fuzzmeasure and 10.4.x? You'd have to use an old version:

http://supermegaultragroovy.com/products/FuzzMeasure2/

As a demo ... I don't recall the limitations.

K184? cardioid recording mics... if you realize they drop off below 100Hz
and have a broad peak at 9KHz they could still be useful, but only if you
understand their limitations (might help in setting crossover frequency
and matching driver levels, but you'd be adding a layer of difficulty in
interpreting much more).

http://www.neumann.com/zoom.php?zoomimg=./assets/diagrams/s180_diagrams.htm&zoomlabel=Diagram&w=878&h=278

Don't expect miracles from the K145 in a small box. Appears that 3ft3
will get you to ~60Hz before roll off.

For the box dimensions I could build a 23"(W)X30"(H)X21"(D) (the available space)this is external measures and I would front mount the woofer and put the horn just above the woofer. I think I would end up around 6cuFT and I guess that it is preferable to have ported enclosure or if I choose closed box I could use more bass extension with the DCX2496 at the expense of power handling for the woofer. Decent bass extension to 30/35Hz (at-3db) would be feasible?

Most use of this system is 50% DVD shows and 25/25% for music playback and films.

[maxserg]

Ok I understand that I need an 8 to 10 inches to make mid-range translation, so I will go higher in the xover but then it will be a tree-way system, that's it!