Adding 2405H to my custom JBL system

[Beowulf57]

Oops, my fault. I didn't read through the whole thread.

Ahh, dats OK This monkey forgot to include the driver impedance in his first attempts at calculating the L-pad attenuation.

[Beowulf57]

Try it in the various configurations and monitor the output on a spectum analyzer. (That's what I use my Behringer for and can spend hours assessing small differences.) Look for the smoothest response using your components in your setting.

Thanks Toddalin...but I haven't got one of those wonderful toys. I used to work with a $25,000 spectrum analyzer decades ago when I was with Raytheon Canada. Now I haven't even got a speculum analyzer...though I know they don't cost that much for audio frequencies.

I'm just trying to iron out any potential problems working from the advice of those more experienced. I want to see how far I can get with the very simple measurements I've used so far and calculations based upon the behaviour of network filters, L-pads and drivers. Hmm...perhaps I could work out a test setup using my high quality HP handheld scope and my audio signal generator.

BY the way...how have your 2312 horns worked out?

[toddalin]

BY the way...how have your 2312 horns worked out?

Each horn is receiving 11 oz of a spray-on rubber coating. On the first horn I did, it changed the "ting" to more of a "tingk" so I figured I would do the other two also. They've now each received 3 coats and will get their final two coats tomorrow.

As my old moil friend used to say "Couldn't hoit."

It is actually pretty cool stuff and leaves a really nice, hard-squishy type feel and looks like they've been powder-coated. No problem sticking to the raw aluminim on the one that had been stripped of finish after wiping them down with alcohol either. (It seems to stick better than paint.)

The rear warts have been complete for some time and today I bought the hardware to mount them.

Now it's just a matter of cutting up (oops, out) the cabinets, mounting the horns, and of course removing and revising the crossovers as best possible using what is available in the parts bin.

[Beowulf57]

Each horn is receiving 11 oz of a spray-on rubber coating. On the first horn I did, it changed the "ting" to more of a "tingk" so I figured I would do the other two also. They've now each received 3 coats and will get their final two coats tomorrow.

As my old moil friend used to say "Couldn't hoit."

It is actually pretty cool stuff and leaves a really nice, hard-squishy type feel and looks like they've been powder-coated. No problem sticking to the raw aluminim on the one that had been stripped of finish after wiping them down with alcohol either. (It seems to stick better than paint.)

The rear warts have been complete for some time and today I bought the hardware to mount them.

Now it's just a matter of cutting up (oops, out) the cabinets, mounting the horns, and of course removing and revising the crossovers as best possible using what is available in the parts bin.

"Looking good Billy Rae...feeling good Louis!"

[Beowulf57]

I finally decided upon my optimal L-pad setting and got rid of those alligator clip leads. Soldered wires to the L-pads and hooked them up to the LE85 driver terminals. Rather than solder pin 2 to the LE85 + wire...I used good old electrical brass insert marrette connectors. Good connection and easy to change later if I wish. Pin 1 to the 3106 ground and pin 3 to the low pass + connectors and all's well.

Final L-pad values: 4.3 ohms series leg and 19.0 ohms parallel leg. This provides roughly -4dB assuming a nominal driver impedance of 12 ohms. If I use a 20 ohm value at 900Hz, it's ~ -3.2dB, almost identical to the difference between the Mid and Min settings on the LX5. So, I've ended up with the LE85 at the effective Min setting and the 2405H at the Mid setting. THis sounds good, though I may lower the HF level very slightly after more listening.

The results to my ears are excellent: gone is any hint of "horniness" (not in me though ), no more glare or excessive brightness and the top end is extended, detailed and refined. Now I have a wonderful bottom to top balance: powerful, deep and controlled low end...rich, clear, detailed midrange...and a far. far better upper octaves than I have ever known before (with apologies to Dickens).

All genres of music sound great:classical, jazz, rock, folk, blues...! I can move through Steve Winwood (Back in the High Life), Celtic harp, Pink Floyd, Oscar Peterson, Bach (Glenn Gould), Vivaldi (viola d'amore), Baroque, Brahms, Beethoven, Jennifer Warnes (Famous Blue Raincoat), B.B. King...well you get the idea. Never once moving from SACD to LP to CD to DVD Audio did I ever feel there was too much of this, or not enough of that. I'll keep everyone updated of any further adjuastments/tweaks and for now would like to send my heartfelt thanks to all of you who have helped me and this forum! I couldn't have done it without you.

[toddalin]

I finally decided upon my optimal L-pad setting and got rid of those alligator clip leads. Soldered wires to the L-pads and hooked them up to the LE85 driver terminals. Rather than solder pin 2 to the LE85 + wire...I used good old electrical brass insert marrette connectors. Good connection and easy to change later if I wish. Pin 1 to the 3106 ground and pin 3 to the low pass + connectors and all's well.

Final L-pad values: 4.3 ohms series leg and 19.0 ohms parallel leg. This provides roughly -4dB assuming a nominal driver impedance of 12 ohms. If I use a 20 ohm value at 900Hz, it's ~ -3.2dB, almost identical to the difference between the Mid and Min settings on the LX5. So, I've ended up with the LE85 at the effective Min setting and the 2405H at the Mid setting. THis sounds good, though I may lower the HF level very slightly after more listening.

The results to my ears are excellent: gone is any hint of "horniness" (not in me though ), no more glare or excessive brightness and the top end is extended, detailed and refined. Now I have a wonderful bottom to top balance: powerful, deep and controlled low end...rich, clear, detailed midrange...and a far. far better upper octaves than I have ever known before (with apologies to Dickens).

All genres of music sound great:classical, jazz, rock, folk, blues...! I can move through Steve Winwood (Back in the High Life), Celtic harp, Pink Floyd, Oscar Peterson, Bach (Glenn Gould), Vivaldi (viola d'amore), Baroque, Brahms, Beethoven, Jennifer Warnes (Famous Blue Raincoat), B.B. King...well you get the idea. Never once moving from SACD to LP to CD to DVD Audio did I ever feel there was too much of this, or not enough of that. I'll keep everyone updated of any further adjuastments/tweaks and for now would like to send my heartfelt thanks to all of you who have helped me and this forum! I couldn't have done it without you.

You're gettin' me jazzed to get mine done. Unforetunately, a few other thing have gotten in the way lately (like redoing our mother-in-laws house who just passed away..., as well as making a living).

Anyway, work progresses slowly.

I've decided to replace the upper center port of my center channel with the H92 and block off the hole where the "potato masher" currently is. This way my L,C,R woofers and horns will all be identical and will all be at ~ the same height.

As it is now, I reach in through this center port to adjust the mid and high levels, so these pads will be moved onto the new block-off plate.

Because the port has a 4" ID and ~4-1/4" OD, if I simply knocked out the port tube, the horn would have a gap around its perimeter. So, I cut a piece of the port material to 5/8" long and using a flapper wheel, milled out the inside diameter to fit around the horn and center it in the hole. When I finally open the cabinets, I like everything ready to go to minimize down time as this is our everyday sound system for our TV viewing

[Beowulf57]

You're gettin' me jazzed to get mine done. Unforetunately, a few other thing have gotten in the way lately (like redoing our mother-in-laws house who just passed away..., as well as making a living).

Anyway, work progresses slowly.

I've decided to replace the upper center port of my center channel with the H92 and block off the hole where the "potato masher" currently is. This way my L,C,R woofers and horns will all be identical and will all be at ~ the same height.

As it is now, I reach in through this center port to adjust the mid and high levels, so these pads will be moved onto the new block-off plate.

Because the port has a 4" ID and ~4-1/4" OD, if I simply knocked out the port tube, the horn would have a gap around its perimeter. So, I cut a piece of the port material to 5/8" long and using a flapper wheel, milled out the inside diameter to fit around the horn and center it in the hole. When I finally open the cabinets, I like everything ready to go to minimize down time as this is our everyday sound system for our TV viewing

Wow...now that is going to be some fun system to audition! I like drivers at the same heights...actually sawed the feet down on my larger cabinet so the horizontal CL of the drivers lined up from left and right.

A bit more tweaking happened today...massed forte strings sounded fine on SACD and CD, but somewhat hot and edgy on LP. Why? Then I recalled that 25 years ago I raised the VTA on my Linn Ittok LVIII tonearm on the LP12 Sondek turntable to compensate for the rolled off top end with the LE85 drivers. Now with the 2405Hs added it was unnecessary and sounded too hard. Down with the tonearm and VTA and after the adjustment: much better! Will the tweaking never end? I hope not!