A new development of my 'SWANSONG' speakers

[gninnam]

I hear you Colin
Enjoy working on the speakers and I hope I get to hear them once up and running!

[Toppsy]

I hear you Colin
Enjoy working on the speakers and I hope I get to hear them once up and running!

You'll certainly get an invite when they are finished. I'm sure Lynn will keep us well fed and watered in her usual way.

[gninnam]

You'll certainly get an invite when they are finished. I'm sure Lynn will keep us well fed and watered in her usual way.

Appreciate and I am sure she will

[Toppsy]

Having emailed Scott a copy the MK1 and MK2 variants of the new speakers for comment, he had a couple of observations. He suggested that for optimum listening the HF driver should be at ear level when seated in the listening position at my home and to keep the bass drivers no higher then they are currently in the original swansongs. I promptly sat in my listening chair and measured the height to my ears, 930mm. Meaning the HF driver in the MK1 and MK2 variants previously posted was not in the optimum position. This resulted in a MK3 design.



So the MK3 variant is the design I shall now go with and is no higher overall then my Edingdale GT speakers. I'll redraw the cabinet design based on this layout and should early next week request quotations for the CNC routed panels and the CNC controlled flatbed bandsaw cut panels in Birch Ply. The Satori drivers are due delivery Monday.

I feel I'm making some progress at last.

[Toppsy]

Quite some progress since last I posted.

• The Satori midrange drivers have arrived and were delivered beginning the week.

• I have modified my CAD drawing to the MK3 variant the cabinet design and emailed a DXF copy with a cutting schedule list to by plywood supplier for a quotation for doing the cutting work. A mixture of CNC routing and straight cut panels on their CNC controlled flat bed beam saw.

• Quotation with nested images of the two sheets of 18mm Birch Ply and cost of the machining plus plywood, received mid week.

• Got a phone call yesterday (Friday) morning that if the price was acceptable and I could pay for the work over the phone, as a favour to me, they could have the work completed by lunchtime and would be ready for collection after 2.30pm

Below is a copy the nested image file that all the panels fit nicely in a couple 2440mm x 1220mm x 18mm sheets of birch ply.


The left side image shows the CNC controlled beam-saw cutting layout with the CNC routed panel layout on the right.

I have to say the quality of the Birch Ply is better then it was last I bought any from them and there are no egg shaped repair patches in any the panels that was evident in the Russian stuff. Not wishing to support the Russian economy, what with the situation in Ukraine, I was somewhat concerned their web site stated the 18mm BBPly was Russian. However having spoken to them, they said that since the invasion by Russia into Ukraine and the trading sanctions imposed they are using various other sources of manufacture and supply and the ply I have is they believe from Finland. I suspect this reflects in the better quality of the plywood today.

So having picked up the cut panels I am now eager to get started in the speaker build. Now where did I put the bottle wood glue and clamps

[Toppsy]

Slight change in the design of these new speakers.
After chatting with Chris661 and Scott over the weekend I have decided to drive these speakers fully active using the 3-way Hypex FusionAmp FA123 modules.
What with the success of the active bass setup on the big'uns it's been an itch I needed to scratch and I thought, these are the last pair of speakers i shall build and develop so lets just go for it.

I'm just in the process of making the changes to the rear baffles to accommodate the FA123 plate amps

[Toppsy]

OK for those following this thread some build photos.

Below shows a full set of cut panels for a single speaker:



Having made quite some progress with the build I have no near completed the build of both cabinets, ready for the internal damping to be applied (12mm thick 100% recycled wool carpet underlay) and then the other side panel to be glue in place. Next step will be to make up the base plinths.







The dark slots that can be observed in the top of the 18mm ply end grain is for the No20 biscuit joints that help accurate assembly and hold the whole speakers together.

More to follow..............

[Nick]

Picky question. Why the holes in the (I assume) reinforcement part behind the mid driver space? Given the symmetry I cant see how you would expect any pressure differential across the spacer, so no air flow, so no need for holes.

[Toppsy]

No Reason Nick other then I needed to have these panels cut from the routed sheet of ply as there was not enough space to have them cut on the band saw schedule from the standard 8'x4' sheet. It cost no more to have those holes routed in the panels so I thought why not.
On the recommendation of Scott that longitudinal brace behind the midrange sub-chamber is laterally offset a little to introduce some asymmetry.

[Nick]

Ok, so the asymmetry would justify the holes, but then the holes would cancel the need for asymmetry

[Toppsy]

Unfortunately no going back now Nick and it is what it is. I can however, line both sides of that brace with the wool underlay which should help with preventing any air bleed through the holes?

[Ali Tait]

Looking good as always Colin!

[Max N]

The asymmetry may be designed to prevent or reduce a resonance in the rear panel of the midrange chamber it is bracing?
Generally it is better to avoid placing bracing panels on the centre line of the panel you are trying to brace. Otherwise the resonant frequency of a standing wave in each half of the panel you are trying to brace is the same.
So what Colin has done makes sense to me.

[Nick]

Unfortunately no going back now Nick and it is what it is.

No, in general I was just messing with you

[Nick]

The asymmetry may be designed to prevent or reduce a resonance in the rear panel of the midrange chamber it is bracing?

Oh, yes, no argument there, it was the holes I was having an "issue" with (And the fact that initially it looked symmetric).

Though would that argument for asymmetry suggest that having the bracing non parallel to the side walls would be advantageous?

Or instead of holes, use a number of separate bracing members not on a single plain, top to bottom but staggered?

But hey, I am just a software engineer who remembers the mech and civil engineering folk I knew at uni having huge amount of work to do for finite element analysis. All I had to do was invert a few matrices .