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Tannoy GRF-Rectangular Horn


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#1 atilsley

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Posted 10 November 2012 - 05:23 PM

Just spent some time ligning up panels for a new Tannoy GRF.

This is the first time I've used lovely Euro Birch from Yates (Sydney), which is a very high quality, void-free 19mm ply.....the veneer is American Walnut.

I'll add additional braching over the original design.

Plinths are 50mm.

Top and side panels very well mitred by Mr Plywood...so no external joins showing...as the sides run all the way to the bottom.

Rear panels fully rebated in...so no trim there.

For front trim, I'll either use Walnut thin veneer glue on veneer...or look around for some thin solid wood.

Heavy for sure, perhaps 60Kgs each.....fun project.

Monitor Golds get ready.

Andrew

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My System: DIYEDEN DAC, Holton Precision Audio 6-channel custom amp, Yuichi 290 horn with Altec 288, Eminence Lab12 bass, MiniDSP.


#2 ortofun

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Posted 10 November 2012 - 08:26 PM

Very nice :thumb:

#3 ehtcom

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Posted 10 November 2012 - 08:31 PM

Nice work Andrew.
May have to visit the lucky bugger getting those ;)

Cheers, Earle.

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#4 atilsley

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Posted 10 November 2012 - 09:57 PM

Yes earle...a visit might be in order.


My System: DIYEDEN DAC, Holton Precision Audio 6-channel custom amp, Yuichi 290 horn with Altec 288, Eminence Lab12 bass, MiniDSP.


#5 atilsley

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Posted 11 November 2012 - 06:32 PM

Spent today drawing up the plans on the inside of one wall of each cabinet. Use small wooden blocks as guides for when fitting the panels. I allow a 1mm gap for the blocks to apply very strong poly glue. Blocks first put down with simple pva.

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My System: DIYEDEN DAC, Holton Precision Audio 6-channel custom amp, Yuichi 290 horn with Altec 288, Eminence Lab12 bass, MiniDSP.


#6 henry218

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Posted 11 November 2012 - 09:00 PM

wow, those looks fantastic. im hoping to get a chance to have a listen at your place :)



#7 atilsley

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Posted 13 November 2012 - 10:02 AM

Glue up continues...note how the poly glue expands forming a very strong and expanded hold. Obviously, you don't want this near visible joins...but for the internal horn panels, I lay it on.

The small white blocks you see half way up the back panel are to mount a brace panel later.

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My System: DIYEDEN DAC, Holton Precision Audio 6-channel custom amp, Yuichi 290 horn with Altec 288, Eminence Lab12 bass, MiniDSP.


#8 THOMO

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Posted 13 November 2012 - 11:28 AM

Nice work Andrew.
Did the ply come with the Walnut veneer or was it custom pressed?
It makes sense to use a veneer that looks good with a simple oil finish as spray finishing these horns is difficult.
I built some with Macassar ebony veneer and finishing the horn sections was a pain using two pack lacquer.
Walnut is one of only a few timbers that looks really good oiled in my opinion.Livos works really well.
AMPLIFICATION-Supratek Cabernet 300B preamp,2 of Usher 1.5 power amps for biamping,Almarro 318B SET ,Gainclone 3876T,Accuphase E202,Nakamichi 420 power.
SPEAKERS-Gale 401a.Edgar horns.Toshiba SS 30s.B&W DM70C Various DIY. DIGITAL-Krell KAV300CD.Sony CDP 715.
VINYL-Technics SP10 in custom lead filled curly jarrah THOMO plinth.Modified Logic DM101.Jelco 750 E 10.5inch tonearm.Soundsmith Supex 900 Super II MC cartridge,Denon ASU320 step-up,Nagaoka MP500 MM.

ABSURDITY-A statement of belief manifestly inconsistent with one's own opinion.....Ambrose Bierce

#9 atilsley

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Posted 13 November 2012 - 01:43 PM

The veneer is laid up by Yates, who import the Euro Birch ply.

I steer clear of lacquers, unless using a pro third party to spray paint...otherwise, it's Bees Wax (which can include a stain in it for even easier application). Plus, for these Tannoys, the ye olde approach suits.

My System: DIYEDEN DAC, Holton Precision Audio 6-channel custom amp, Yuichi 290 horn with Altec 288, Eminence Lab12 bass, MiniDSP.


#10 ENIGMA

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Posted 13 November 2012 - 02:01 PM

I like these!

Will be very nice in deed to have.
Horns with ion generators.

#11 a.dent

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Posted 13 November 2012 - 04:14 PM

Beautiful work Andrew

I have another pair of 15" Monitor Golds that I just obtained that are looking for suitable cabinets.

That American Walnut looks a treat.

I hope the sound matches the looks.

Andrew

#12 atilsley

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Posted 13 November 2012 - 04:29 PM

Andrew

If in Sydney, why not visit in about one week with your drivers....? The high density ply and extra bracing should make this speaker sound a treat.

Be loving to your monitor golds....they deserve the best of homes...! Putting them in standard ported boxes is akin to testing a Ferrari on parramatta rd in peak hour.

My System: DIYEDEN DAC, Holton Precision Audio 6-channel custom amp, Yuichi 290 horn with Altec 288, Eminence Lab12 bass, MiniDSP.


#13 atilsley

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Posted 14 November 2012 - 06:49 PM

Not a lot of time spare today...so I glued up the plinths. I use PVA for the corners as this glue very easy to work with and clean up...don't want any nasty stuff on the veneer. I use Selly's poly Aquadhere for the corner blocks, plus for mounting to the base of the cabinet (along with long screws). I've drawn up all the circles for the baffle and rear panel cutouts...but will leave the routering to another day. On Sat, I'll have Mr Plywood attend to some more mitres.

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My System: DIYEDEN DAC, Holton Precision Audio 6-channel custom amp, Yuichi 290 horn with Altec 288, Eminence Lab12 bass, MiniDSP.


#14 ehtcom

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Posted 14 November 2012 - 07:11 PM

Looking good Andrew. :thumb:

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#15 atilsley

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Posted 17 November 2012 - 09:16 PM

Today, I routered the holes for the front baffles, glued them up...plus glued in the rest of the main panels. Boy, tough job with router on the thin layered and heavy duty ply. Burnt out one router bit...and took about 8 individual runs to get through the 19mm ply. I mitred the bottom of the front baffle at 45 degrees, then mitred the corresponding bottom angled piece to create a clean join for the veneer.

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Edited by atilsley, 17 November 2012 - 09:19 PM.

My System: DIYEDEN DAC, Holton Precision Audio 6-channel custom amp, Yuichi 290 horn with Altec 288, Eminence Lab12 bass, MiniDSP.


#16 atilsley

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Posted 18 November 2012 - 08:06 PM

Wool/fibre product cut and glued in. Used Walnut wood putty to seal small joins.

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My System: DIYEDEN DAC, Holton Precision Audio 6-channel custom amp, Yuichi 290 horn with Altec 288, Eminence Lab12 bass, MiniDSP.


#17 henry218

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Posted 20 November 2012 - 01:51 PM

hi andrew,

is that magnet holder behind the cutout for the driver?

henry

#18 atilsley

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Posted 21 November 2012 - 07:27 AM

hi andrew,

is that magnet holder behind the cutout for the driver?

henry


Yes, the design is odd, in thatthe rear of the driver protrudes through the second panel. See here -

My System: DIYEDEN DAC, Holton Precision Audio 6-channel custom amp, Yuichi 290 horn with Altec 288, Eminence Lab12 bass, MiniDSP.


#19 henry218

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Posted 21 November 2012 - 09:32 AM

wow, thats cool!. almost similar to ORION decoupled midrange mounting. it works both ways i think, keeping the length of the horn, and minimizing vibration coming out of the woofer.

great design.

#20 atilsley

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Posted 24 November 2012 - 07:38 PM

Final internal pieces added today, with sound deadening. Will glue up sides tomorrow and add plinths.

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Edited by atilsley, 24 November 2012 - 07:43 PM.

My System: DIYEDEN DAC, Holton Precision Audio 6-channel custom amp, Yuichi 290 horn with Altec 288, Eminence Lab12 bass, MiniDSP.


#21 Jake

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Posted 24 November 2012 - 07:51 PM

I love these threads but don't always make a comment. I have made a few speakers myself, but don't really know what I'm doing :P

I am curious about the use of that lovely veneer inside the box where you will never see it again though! Seems like such a waste, when you could have used cheaper non-veneered material. Is it a SQ consideration at all?

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#22 guru

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Posted 24 November 2012 - 08:32 PM

I love these threads but don't always make a comment. I have made a few speakers myself, but don't really know what I'm doing :P

I am curious about the use of that lovely veneer inside the box where you will never see it again though! Seems like such a waste, when you could have used cheaper non-veneered material. Is it a SQ consideration at all?

evening jake , veneer panels are always layered up equally so there is equal tension on both sides of the board otherwise you will get a cupping effect and the panel will distort in shape and you have to use the same material both sides or there will be an uneven movement. some furniture fnishers will apply a finish to the never to be seen panel internally so as to minimise movement in responding to moisture in the air as would be the case with a coating on one face and not on the other.
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#23 Jake

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Posted 24 November 2012 - 08:38 PM

evening jake , veneer panels are always layered up equally so there is equal tension on both sides of the board otherwise you will get a cupping effect and the panel will distort in shape and you have to use the same material both sides or there will be an uneven movement. some furniture fnishers will apply a finish to the never to be seen panel internally so as to minimise movement in responding to moisture in the air as would be the case with a coating on one face and not on the other.
regards,g.

Ahh, thanks Guru. I suspected there was a valid reason for it. Appreciate your explanation.

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#24 Soul Superfly

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Posted 25 November 2012 - 07:01 AM

Hi Jake, As Guru states and also my veneer supplier, it is there to keep the plywood in balance, although there is usually a perfect side and a not so good side so it pays to inspect the veneer sheet before cutting. If you have ever painted a free piece of board on one side only you can often see the cupping caused by the different surface tensions acting. I manufactured a Pair of Dallas II speakers for a customer using the same ply and methods, but used new cat litter for the voids except for the lower void where i used oven dried river sand. I found this keeps the upper weight down quite and lowers the centre of gravity in an attempt to make them more stable.

http://s78.beta.phot...llas II Project

Regards, Nick

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#25 atilsley

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Posted 25 November 2012 - 07:57 AM

Love the Dallas...a great speaker...well done....similar to the Medallion, which was my first ever horn I built.

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My System: DIYEDEN DAC, Holton Precision Audio 6-channel custom amp, Yuichi 290 horn with Altec 288, Eminence Lab12 bass, MiniDSP.


#26 atilsley

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Posted 25 November 2012 - 07:03 PM

One top and one side added today.

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My System: DIYEDEN DAC, Holton Precision Audio 6-channel custom amp, Yuichi 290 horn with Altec 288, Eminence Lab12 bass, MiniDSP.


#27 atilsley

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Posted 28 November 2012 - 12:21 PM

Plinths being glued on.

Just need to finish front trim and grill frames.

Attached Files


My System: DIYEDEN DAC, Holton Precision Audio 6-channel custom amp, Yuichi 290 horn with Altec 288, Eminence Lab12 bass, MiniDSP.


#28 atilsley

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Posted 01 December 2012 - 01:47 PM

Trim glued on...and getting ready for final sanding. Clocking up the hours on this build....

Attached Files


My System: DIYEDEN DAC, Holton Precision Audio 6-channel custom amp, Yuichi 290 horn with Altec 288, Eminence Lab12 bass, MiniDSP.


#29 THOMO

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Posted 01 December 2012 - 06:42 PM

Looking good Andrew.
Have you tried polyeurathane glue on the trim?
It froths up but then is very easy to sand back and does not discolour the timber like PVA and epoxy.Vice Grip seems a decent brand you can buy at Bunnings.

It also might pay to chamfer the bottom of the plinth quite strongly as the veneer tends to catch on carpet and ends up being torn off.The classic Klipsch speakers tended to do this.
AMPLIFICATION-Supratek Cabernet 300B preamp,2 of Usher 1.5 power amps for biamping,Almarro 318B SET ,Gainclone 3876T,Accuphase E202,Nakamichi 420 power.
SPEAKERS-Gale 401a.Edgar horns.Toshiba SS 30s.B&W DM70C Various DIY. DIGITAL-Krell KAV300CD.Sony CDP 715.
VINYL-Technics SP10 in custom lead filled curly jarrah THOMO plinth.Modified Logic DM101.Jelco 750 E 10.5inch tonearm.Soundsmith Supex 900 Super II MC cartridge,Denon ASU320 step-up,Nagaoka MP500 MM.

ABSURDITY-A statement of belief manifestly inconsistent with one's own opinion.....Ambrose Bierce

#30 Soul Superfly

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Posted 01 December 2012 - 07:06 PM

Thomo, the plinth looks like natural timber, not veneered. Maybe he does not need to veneer and chamfer this part, I am a bit traditional in that I like to see plinths painted black and then they can 'disappear' Kind regards,, Nick

Vortexbox - Marantz CD - Eastern Electric 32 Bit Tube DAC Plus - Earle Weston Time machine 300B - Zu Libtec - ZU Soul Superfly MK.1-B Modified :) - & - Icon Audio 40-6AS7, Abbey Road Studio Cables, Paradigm Reference Studio 60's V5 - Stax  SRM-T1