Ian's (& Bo's) 4345 project

[boputnam]

Originally posted by Ian Mackenzie
That said I would like the option of baffle removal at least initially in case anything is overlooked or needs changing.

Won't work, IMHO. I've struggled with this in the modified L65's I finishing, and simply cannot get the box airtight. Real bugger. What I have done, but don't take the listening as "final", is hold the baffle on with massive wood clamps, but it ain't sightly.

[maxwedge]

Those screws look a little weak. I think you're better off with some longer bolts, with tappered heads, going through the bracing to T-nuts. If it's temp then I would skip the tappered heads and use a large washer under the bolt head to try and hold it together. I think we'd be talking about 3" bolts depending on the bracing.

Scott

[Robh3606]

Didn't the 4343 or 4344 have a rotateable baffle panel?? Anyone know what JBL used. Hey Mike Baker those 3115 have a rotateable baffle what do they use there??

Rob

[Ian Mackenzie]

Thanks everyone.

I'm not alone here.....

I thought about bolting right through...100 mm bolts with T nuts.

I'm using these for the *mid cone and woofers. (*JBL supplied the former)

I think the down side for the baffle is getting the long hole plum and finding a suitable bolt head...flush/counter sink...would grind into the soft MBF and make a messy finish of my paint

Regards the hardware in the pic, they appear quite strong, the bolts are M6 threaded with 4mm hex drive, the larger diameter head ensures excellent joint strength according to the packaging

On the packaged of the Scew insert nut they quote postive locking and strong pullout resistance due to torsion or vibration.

I figured 6- 8 inch spacing would be plenty and once I am cool about it all I can go permanent or glue. The soft cell foam rubber has an adhesive backing and sufficient give for an air tight seal under pressure.

Ian

Ps like my new avatar...muhahahah

[Ken Pachkowsky]

Hi Ian

Just wanted to drop a line and deliver some well deserved compliments on your project. Fine job your doing!!

Happy New year.

Ken

[Ian Mackenzie]

Thanks Ken,

Well we are keeping this in the family after all..............

It rained continuously all day here so I enjoyed the solitude of working on the project while playing all my Pink Floyd albums in the background.

Today I designed and built the rear loading dock (removable rear access panel) . Quite an intersting challenge actually to maintain the integrity of the enclosure while also providing a removable sealed panel.

Its quite neat, the lower horizontal flange interlocks with the rear vertical bracing forming a double T section stiffener. The flange is made from two peices of F17 hardwood glued and screwed to the fixed section of the rear MDF panel. The side and top flanges will mount against the existing frame.

This graphic in Paint highlights the bracing (air brushed ) within the overall structure.

[Ian Mackenzie]

Here's a sneak view from the 4345 Live Cam (low res)

Ian

[Ian Mackenzie]

Closer

Ian

[boputnam]

Very cool, Ian - great job...

I am goofed on seeing my 4345's as your avatar! That is stunner! Flattered... :o

I wish I had the skillset you have, and ability to fabricate some new passive crossovers for these. I'm sure they'd benefit from renewing some of the components...

[Ian Mackenzie]

"I wish I had the skillset you have, and ability to fabricate some new passive crossovers for these. I'm sure they'd benefit from renewing some of the components..."

What, You started all this with your imperial tape measure.

Bo, your speakers are operating in bi amp mode. This overcomes the primary source of passive crossover limitation in this design, the smaller value capacitors for the horn and slot are less likely to be an issue.

My view is the existing active crossover you are using is the limiting factor here.

I will devise an exotic discrete active crossover for the 4345 monitor as soon as time permits.

As the first recipient of this new active crossover and I am sure your expectations of the 4345 will elevate to a new level.

And then perhaps little while later a very substantial cast aluminium heat exchanger will arrive on your door step to finish the job.

Ian

[Ian Mackenzie]

Some pictures to follow shortly,

Both cabinets are now nearly complete, only mounting of the baffles, drivers and crossovers remaain.

At the moment I am stopping up all the screw holes in preparation for finishing.

I acquired new fibreglass batts yesterday (at no charge) from the local hardware and enough of those bolt fasterners to build the QE2.

I have decided to make the baffle permanent following a dry fit up. The main reason is maximum bond strength with the enclosure and baffle, in fact I purchased hi grade PVA glue for the job.

I am very pleased with the way the boxes are turning out and with the rear access panel a removeable front baffle seems redundant.

With any luck I will be posting hi resolution images by next weekend. I trust there will be some similarity with the original design.

Ian

[jandregg]

Ian, in 1974 I built two 6 cu boxes. I framed the front baffle opening with 2 x 2, and used cloth felt ( .1 inch thick) as a gasket. These are still my main speakers after four cross county moves and a fair number of years.

John

[Daniel B]

Originally posted by Ian Mackenzie
I am very pleased with the way the boxes are turning out and with the rear access panel a removeable front baffle seems redundant.

Only until the day after the glue has dried.

dB

[Ian Mackenzie]

Your right,

The dry fit will be the clincher and will pay to be maticulous with the fitting up, no second chances here.

Regardless I will be squirting a bead of liquid nails or Bostick sealer around all the inside surface joints.

As it is I have had to block and plug the previous 3 side vent holes like a wine maker re sealing the bottle.

Damm shame really about those side ports, good bye to Harley and Charlie....

As you can see here I have about 2 1/2 inches of mating surface to contact with and plan on being liberal with the glue...alas I plan on having a helper with all that white sticke stuff, drying time is only 30 minutes

Ian

[Ian Mackenzie]

Finally this afternoon I did the 1st successful dry fit of the baffles.

Not an easy job on an enclosure of this scale, damm heavy too.

They must have taken a long time to make in the factory.....that would be an interesting topic to research.

Both baffles now glued and fixed with 16 bolts to the enclosure.

The boxes is now particularly heavy and solid.

The next step will be to sand down and re finish the enclosures.



Ian