Powerglide Posted June 12, 2023 Share Posted June 12, 2023 Through SNA I meet a group of guys who love large format speakers and over the last few years I’ve been lucky enough to listen to a bunch of Altec drivers in different enclosures with different horns. I’ve always wanted to have a go at the horn flares on one of the VOTT models and semi jumped at the opportunity when asked by a friend for a set of 825. Following the modification’s recommended in the Small ‘Classic’ “Voice of the Theater” paper by Jim Dickinson and popularised by Jean Hiraga, former chief editor of L’Audiophile magazine and his friend John Stronczer, founder of Bel Canto, as published in the Sound Practices 5 article La Voice Of The Theatre Chez Nous. https://wajonaudio.webs.com/Voice of the theatre.pdf We upgraded the ply to 25mm Birch, I converted the dimensions from imperial to metric and recalibrated the sizes to suit the thicker material matching the original internal volume. Having restored a pair in the past I knew I could improve on the detail and finish of the boxes and made some subtle changes. First change was to mitre all the corners and use locating dominoes in all the joints The later model 828 had a full baffle from side to side enclosing the rear of the horn flare, we morphed this detail into the 825’s taking shape with the horn ribs installed I used 5 layers of 5mm bending ply, gluing and stapling each layer, clamping the final laminate in position. Another subtle change from me here, I finished the flare into the side of the speaker just a quirk short of the front edge. This keeps the internal lines flowing from ports through to the flares, The originals were quite clunky stepping in 15mm or so. Added glue blocks to the corners, glued and screwed timber cleats in position to take the removable panels Another slight change here, this port set up is from the 828b, purely aesthetic Rebated the aperture of the panel to slim down the internal front edge, aesthetic again. Made up some frames for fixing the cloth in position. All the removable panels with be fitted with countersunk machine screws and timber nutserts, rear panels shown here with the terminal positioning Little mock up. The panel above the port is screw fixed from the inside, no glue so in the event of swapping drivers, or just for giggles, the ports can opened up or reconfigured I put a skim coat of resin over the bending ply to fill the open grain Couple of coats of high build undercoat Sanding, bit of filler here and there, more sanding After another undercoat and some more sanding, I chickened out and had a friend of mine put the top coats on Open day at the workshop @cccrchairman install some sound deadening And fitted the grill cloth bolted together for transport This next step was slightly crazy but cool, little joy ride up the river made it to the listening shack without damage, fitted the woofers Taking some license on the specific drivers the speakers are A5B/MRII594A. At the moment the woofers are 416-8a, compression drivers are 288-16G and horns are MRII59A. Hiraga crossovers. TT, power and liquid refreshments, not a bad afternoon. 12 9 4 Link to comment Share on other sites More sharing options...
mwhouston Posted June 12, 2023 Share Posted June 12, 2023 9 hours ago, Powerglide said: Through SNA I meet a group of guys who love large format speakers and over the last few years I’ve been lucky enough to listen to a bunch of Altec drivers in different enclosures with different horns. I’ve always wanted to have a go at the horn flares on one of the VOTT models and semi jumped at the opportunity when asked by a friend for a set of 825. Following the modification’s recommended in the Small ‘Classic’ “Voice of the Theater” paper by Jim Dickinson and popularised by Jean Hiraga, former chief editor of L’Audiophile magazine and his friend John Stronczer, founder of Bel Canto, as published in the Sound Practices 5 article La Voice Of The Theatre Chez Nous. https://wajonaudio.webs.com/Voice of the theatre.pdf We upgraded the ply to 25mm Birch, I converted the dimensions from imperial to metric and recalibrated the sizes to suit the thicker material matching the original internal volume. Having restored a pair in the past I knew I could improve on the detail and finish of the boxes and made some subtle changes. First change was to mitre all the corners and use locating dominoes in all the joints The later model 828 had a full baffle from side to side enclosing the rear of the horn flare, we morphed this detail into the 825’s taking shape with the horn ribs installed I used 5 layers of 5mm bending ply, gluing and stapling each layer, clamping the final laminate in position. Another subtle change from me here, I finished the flare into the side of the speaker just a quirk short of the front edge. This keeps the internal lines flowing from ports through to the flares, The originals were quite clunky stepping in 15mm or so. Added glue blocks to the corners, glued and screwed timber cleats in position to take the removable panels Another slight change here, this port set up is from the 828b, purely aesthetic Rebated the aperture of the panel to slim down the internal front edge, aesthetic again. Made up some frames for fixing the cloth in position. All the removable panels with be fitted with countersunk machine screws and timber nutserts, rear panels shown here with the terminal positioning Little mock up. The panel above the port is screw fixed from the inside, no glue so in the event of swapping drivers, or just for giggles, the ports can opened up or reconfigured I put a skim coat of resin over the bending ply to fill the open grain Couple of coats of high build undercoat Sanding, bit of filler here and there, more sanding After another undercoat and some more sanding, I chickened out and had a friend of mine put the top coats on Open day at the workshop @cccrchairman install some sound deadening And fitted the grill cloth bolted together for transport This next step was slightly crazy but cool, little joy ride up the river made it to the listening shack without damage, fitted the woofers Taking some license on the specific drivers the speakers are A5B/MRII594A. At the moment the woofers are 416-8a, compression drivers are 288-16G and horns are MRII59A. Hiraga crossovers. TT, power and liquid refreshments, not a bad afternoon. Absolutely excellent work and top craftsmanship. Double the enjoyment for a job well done and now years of listening pleasure ahead. 2 Link to comment Share on other sites More sharing options...
Mr_Fried Posted June 12, 2023 Share Posted June 12, 2023 Extraordinary work Alan, so great to see this project come together. Now we need to crowdsource a hifi sub for @cccrchairman thats capable of some serious midbass kick to integrate with the big A7’s. Anyone know of some Aslan Acoustics PRO12’s that may be kicking around? 1 Link to comment Share on other sites More sharing options...
TelePhil Posted June 13, 2023 Share Posted June 13, 2023 Excellent work. They look fabulous. Link to comment Share on other sites More sharing options...
dwbasement Posted June 13, 2023 Share Posted June 13, 2023 (edited) Fantastic craftsmanship. Edited June 13, 2023 by dwbasement Link to comment Share on other sites More sharing options...
MGO Posted June 13, 2023 Share Posted June 13, 2023 Those speakers look fantastic Alan. Another great achievement. I look forward to hearing them in situ. Love the delivery. Unique. Link to comment Share on other sites More sharing options...
LogicprObe Posted June 13, 2023 Share Posted June 13, 2023 Bloody marvelous! Link to comment Share on other sites More sharing options...
cccrchairman Posted June 14, 2023 Share Posted June 14, 2023 Bloody marvellous sums it up perfectly. It was a 50/50 call to go onken or A5. Alan was keen to have a stab at the horn flares and I had a feeling he was going to hit it out of the park. So I took one for the team. Big thanks to the master craftsman for taking a classic Altec design and respectfully notching it up to 11. Thanks also to the rest of the Altec / large format guys for all the help along the way. 2 Link to comment Share on other sites More sharing options...
couchy Posted June 14, 2023 Share Posted June 14, 2023 On 12/06/2023 at 11:34 PM, Powerglide said: Through SNA I meet a group of guys who love large format speakers and over the last few years I’ve been lucky enough to listen to a bunch of Altec drivers in different enclosures with different horns. I’ve always wanted to have a go at the horn flares on one of the VOTT models and semi jumped at the opportunity when asked by a friend for a set of 825. Following the modification’s recommended in the Small ‘Classic’ “Voice of the Theater” paper by Jim Dickinson and popularised by Jean Hiraga, former chief editor of L’Audiophile magazine and his friend John Stronczer, founder of Bel Canto, as published in the Sound Practices 5 article La Voice Of The Theatre Chez Nous. https://wajonaudio.webs.com/Voice of the theatre.pdf We upgraded the ply to 25mm Birch, I converted the dimensions from imperial to metric and recalibrated the sizes to suit the thicker material matching the original internal volume. Having restored a pair in the past I knew I could improve on the detail and finish of the boxes and made some subtle changes. First change was to mitre all the corners and use locating dominoes in all the joints The later model 828 had a full baffle from side to side enclosing the rear of the horn flare, we morphed this detail into the 825’s taking shape with the horn ribs installed I used 5 layers of 5mm bending ply, gluing and stapling each layer, clamping the final laminate in position. Another subtle change from me here, I finished the flare into the side of the speaker just a quirk short of the front edge. This keeps the internal lines flowing from ports through to the flares, The originals were quite clunky stepping in 15mm or so. Added glue blocks to the corners, glued and screwed timber cleats in position to take the removable panels Another slight change here, this port set up is from the 828b, purely aesthetic Rebated the aperture of the panel to slim down the internal front edge, aesthetic again. Made up some frames for fixing the cloth in position. All the removable panels with be fitted with countersunk machine screws and timber nutserts, rear panels shown here with the terminal positioning Little mock up. The panel above the port is screw fixed from the inside, no glue so in the event of swapping drivers, or just for giggles, the ports can opened up or reconfigured I put a skim coat of resin over the bending ply to fill the open grain Couple of coats of high build undercoat Sanding, bit of filler here and there, more sanding After another undercoat and some more sanding, I chickened out and had a friend of mine put the top coats on Open day at the workshop @cccrchairman install some sound deadening And fitted the grill cloth bolted together for transport This next step was slightly crazy but cool, little joy ride up the river made it to the listening shack without damage, fitted the woofers Taking some license on the specific drivers the speakers are A5B/MRII594A. At the moment the woofers are 416-8a, compression drivers are 288-16G and horns are MRII59A. Hiraga crossovers. TT, power and liquid refreshments, not a bad afternoon. Amazing work. 1 Link to comment Share on other sites More sharing options...
Andrew Tilsley Posted June 14, 2023 Share Posted June 14, 2023 I loved seeing the pics, thanks...very good workmanship. I used a fair bit of CNC'ing to build an A7. For fun, I CNC'd "VOTT" into the baffle/venting. I had adjustable port tuning panels. Went to a gent in Sydney who paired this with 250Hz Jabo horn and 288 drivers. Xover was from a guy in Germany, nice gear. 6 Link to comment Share on other sites More sharing options...
Powerglide Posted June 16, 2023 Author Share Posted June 16, 2023 @simo8989 Interesting, are the ports tuned internally on that CNC’ed panel or have you got different panels that swap out on the port exit 1 Link to comment Share on other sites More sharing options...
simo8989 Posted June 16, 2023 Share Posted June 16, 2023 1 minute ago, Powerglide said: @simo8989 Interesting, are the ports tuned internally on that CNC’ed panel or have you got different panels that swap out on the port exit I had 3 different panels made with difference size ports but ended up using the open port it self because it sounded right. I still want to do some fine tuning on the port to get it spot on. The internals are very different to the original design it was over engineered!!! 3 Link to comment Share on other sites More sharing options...
Powerglide Posted June 16, 2023 Author Share Posted June 16, 2023 (edited) Nice Edited June 16, 2023 by Powerglide 1 Link to comment Share on other sites More sharing options...
mwhouston Posted June 16, 2023 Share Posted June 16, 2023 On 15/6/2023 at 8:07 AM, Andrew Tilsley said: I loved seeing the pics, thanks...very good workmanship. I used a fair bit of CNC'ing to build an A7. For fun, I CNC'd "VOTT" into the baffle/venting. I had adjustable port tuning panels. Went to a gent in Sydney who paired this with 250Hz Jabo horn and 288 drivers. Xover was from a guy in Germany, nice gear. Got an image of the Xover and a schematic. Link to comment Share on other sites More sharing options...
simo8989 Posted June 16, 2023 Share Posted June 16, 2023 1 hour ago, mwhouston said: Got an image of the Xover and a schematic. The Xovers I was using at that time were Werner Jagusch crossovers which were great because you can use different value drivers because they are old school auto transformer Xovers and had 3 different LF at 500hz, 650hz and 800hz plus 11 db adjustment for the HF. They are still available from him on EBay. See link below. At that time I was trying out different LF drivers and small and large format compression drivers, but I am now using a purpose built Jean Hiraga crossover for an Altec 416-8A LF driver and an Altec 288-C 24ohm HF driver. https://www.ebay.com.au/itm/225486383365?hash=item3480092905:g:LxMAAOSwmjdkGnGQ&amdata=enc%3AAQAIAAAAwNQIJkxkTJg23Oi3qtpnZAJUYNUbJHiYerLZTuGlx7Av%2BeDSOUVNSHFxfxNcauD9KvwschVWQDQlUvZ818QgDDlORapphkzXej5CG53LNcfdCLyn%2FRR5a%2Fheb3QAZyMs0bveio5ZITyOkKa%2FYVp7NjMcEPMk2PvOSwzvVihQRuWr%2F%2Fl%2BS1MR85lR4OhWlXEstf9y1kugElvVvYaQYEtvU%2ByQKKcBTmFLnb%2B7FSXTLIMa7Snl0VnvYfjwK%2BkqdzkfmA%3D%3D|tkp%3ABk9SR6iH8cWYYg 1 1 Link to comment Share on other sites More sharing options...
mwhouston Posted June 16, 2023 Share Posted June 16, 2023 1 minute ago, simo8989 said: The Xovers I was using at that time were Werner Jagusch crossovers which were great because you can use different value drivers because they are old school auto transformer Xovers and had 3 different LF at 500hz, 650hz and 800hz plus 11 db adjustment for the HF. They are still available from him on EBay. See link below. At that time I was trying out different LF drivers and small and large format compression drivers, but I am now using a purpose built Jean Hiraga crossover for an Altec 416-8A LF driver and an Altec 288-C 24ohm HF driver. https://www.ebay.com.au/itm/225486383365?hash=item3480092905:g:LxMAAOSwmjdkGnGQ&amdata=enc%3AAQAIAAAAwNQIJkxkTJg23Oi3qtpnZAJUYNUbJHiYerLZTuGlx7Av%2BeDSOUVNSHFxfxNcauD9KvwschVWQDQlUvZ818QgDDlORapphkzXej5CG53LNcfdCLyn%2FRR5a%2Fheb3QAZyMs0bveio5ZITyOkKa%2FYVp7NjMcEPMk2PvOSwzvVihQRuWr%2F%2Fl%2BS1MR85lR4OhWlXEstf9y1kugElvVvYaQYEtvU%2ByQKKcBTmFLnb%2B7FSXTLIMa7Snl0VnvYfjwK%2BkqdzkfmA%3D%3D|tkp%3ABk9SR6iH8cWYYg Serious Xovers. 2 Link to comment Share on other sites More sharing options...
simo8989 Posted June 16, 2023 Share Posted June 16, 2023 4 hours ago, Powerglide said: Nice Thanks the port is very close to the Jean Hiraga port size when he did his modification on his Altec A5’s see link below. https://wajonaudio.webs.com/Voice of the theatre.pdf No I’m no longer using the Vitavox CN 351 drivers at that time I was trying all types of drivers Altec 515, Altec 416 and Vitavox all great drivers I ended up using the Altec 416-8A driver the Vitavox was a close 2nd choice. Final configuration is 416-8A LF and Large format Altec 288C 24ohm HF with custom built Jean Hiraga crossovers end game for me now. 3 1 Link to comment Share on other sites More sharing options...
MGO Posted June 16, 2023 Share Posted June 16, 2023 That's a great article you reference Fred. https://wajonaudio.webs.com/Voice of the theatre.pdf 2 Link to comment Share on other sites More sharing options...
MarcAL Posted June 18, 2023 Share Posted June 18, 2023 This latest build is very well executed, worth the effort and will last a lifetime of listening enjoyment without any doubt. Seriously excellent work all round guys! 1 Link to comment Share on other sites More sharing options...
lowpoke Posted June 25, 2023 Share Posted June 25, 2023 Fantastic work @Powerglide. I know how good they likely sound. (I have a big four way horn setup using 288s.) 2 Link to comment Share on other sites More sharing options...
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