Which Tannoys, folks?

[walpurgis]

Looking good!

But will you be able to move them? They're going to weigh something.

[realysm42]

Great work so far, I'm excited to see the end result!

BTW, when leaving things to dry, do you have the heating turned right up (guessing no) and do you worry about damp this time of year?

[Reffc]

Great work so far, I'm excited to see the end result!

BTW, when leaving things to dry, do you have the heating turned right up (guessing no) and do you worry about damp this time of year?

I don't leave the heating up (too miserly) so rely on leaving things for longer! No worries about damp. The glue will set irrespective and the lacquer is water based after all! The ply is top quality Birch ply and it won't be subjected to particularly high humidity in the workshop.

[Reffc]

Looking good!

But will you be able to move them? They're going to weigh something.

Hi Geoff

They're going to weight far more than I anticipated! The weight of each side panel is 15Kg, so there's around 35 to 40Kg in each hollow shell and that's before front and rear panels are fitted, all the internal bracing and sloping internal base, all the bitumastic sheeting, the drivers, the fittings, and the grill. 70 to 75Kg each is probably a good estimate but I'll weight them when done. No way are they a single person lift. It'll be minimum a two man lift per box.

[Jonboy]

Looking really nice Paul

[Reffc]

Cheers Jon.

A little more progress. Sloping internal base is now in and braced very sturdily from underneath. Braces for one speaker are also in and rear panel is about ready to glue into place. Net internal volume works out at 158 litres, so the braces, front baffle internal laminations, ports and driver and bitumen sheeting take up a surprising 20 litres of volume.

I'm teetering on the edge of revising the porting arrangements to more an EBS design by lowering resonant frequency to 28 Hz to flatten out the bass response and remove the slight peaky response of the twin ports tuned for 33 Hz. The Alex Garner recommendation was 35 Hz with two ports but the response models as quite peaky and could lead to boominess in room. I know that I have a lift at 28/35/72Hz of over 6dB and that twin port tuning (200 long 100 dia) results in bass being just 3dB down at 38 Hz and -7dB at 30Hz.

A 120mm long single port is just -5dB down between 30 and 50 Hz before gently rising to zero at 500Hz. Seems a better tuning arrangement to me. The tuning is a remarkable 28Hz at -6dB which is some serious bass!

I'd be happy to take advice off anyone who's tried either of these tuning points for a cabinet between 150 and 170 litre volume plus any subjective impressions of in-room response. Need to know before midweek next week as that's when I'll be sorting the front baffles and ports!

The two tuning options are shown below. Green line is twin port 33.5Hz and red line is single port, 28Hz tuning:

[Reffc]

Updated pics of the internal sloping base and bracing now completed for one of the cabinets.





Got the other one to do then the back panels will be glued into place. I'll be sealing and painting the rear panels rather than veneering. They'll be finished in a high gloss piano black finish. I'm going to add a small brass plate with the name of the loudspeaker at the back. trouble is, I haven't thought of a name yet....could this be an AoS competition I feel coming on?

[walpurgis]

You could call it the 'Ohmygawdthisisgoingtotakefourofus'

[julesd68]

"The Gloucester".

[Reffc]

You could call it the 'Ohmygawdthisisgoingtotakefourofus'

That's closer to the truth than you might imagine!