vacuum forming?
rabw,
I like how smooth your lenses came out on the front. I have thought to get a mirror smooth surface on the rear could be done with vacuum forming techniques. You could place a bag over the whole horn or prearrange to have it wrapped on the bottom of your mold and wrap it completely around after all of the lay up work was finished and use a vacuum pump to remove all of the air and I think this might form a mirror smooth back side as well as your front.
Has anyone tried this? Would this give a smooth side to the front and back halves?
Regards, Bill
rabw,
I like how smooth your lenses came out on the front. I have thought to get a mirror smooth surface on the rear could be done with vacuum forming techniques. You could place a bag over the whole horn or prearrange to have it wrapped on the bottom of your mold and wrap it completely around after all of the lay up work was finished and use a vacuum pump to remove all of the air and I think this might form a mirror smooth back side as well as your front.
Has anyone tried this? Would this give a smooth side to the front and back halves?
Regards, Bill
Hi, a bit late to this thread as I don't really browse the full range forum.
The horns look excellent - well done. Any response measurements ?
Did you try using a mould release agent on the mould before glassing ?
http://www.cfsnet.co.uk/acatalog/CFS_Catalogue__Release_Agents_76.html
Cheers,
Rob.
The horns look excellent - well done. Any response measurements ?
Did you try using a mould release agent on the mould before glassing ?
http://www.cfsnet.co.uk/acatalog/CFS_Catalogue__Release_Agents_76.html
Cheers,
Rob.
Bill, This might be a possibility, but if vacuum forming you could just vacuum form the whole horn - no grp at all. I did look into this, but nobody had a vac-form machine big enough to handle it on campus. I've got a load of car filler off ebay and am going to use this to get the back flat. The horns i am using are alot flatter on the rear side than the 1st one I did (the black one) because of more time spent with the wire wound roller.
Hi Rob, yes I used plenty of release agent, apparently its common to have to resort to destroying the mould if its a plaster mould. It is no problem fibreglassing onto the new GRP mould, comes off after about 20 minutes of work without having to pull too hard.
I havent got any measurements as of yet. Matt has got a mic + mic amp and should get it sorted to take some measurements in about a months time - if not I'll try get my head around the things that must be done to use it with speaker workshop (i think he's intending to use), but right now he knows what must be done, I havent read up on it yet.
Currently I'm finishing off my dissertation for a week monday and have probably cut about half of the wood for bass cabs. Once my dissertation is in I'll have all my time to crack on with these speakers. A week monday I will have around 4 weeks until they must be completely finished... so lots to do.
Richard.
Hi Rob, yes I used plenty of release agent, apparently its common to have to resort to destroying the mould if its a plaster mould. It is no problem fibreglassing onto the new GRP mould, comes off after about 20 minutes of work without having to pull too hard.
I havent got any measurements as of yet. Matt has got a mic + mic amp and should get it sorted to take some measurements in about a months time - if not I'll try get my head around the things that must be done to use it with speaker workshop (i think he's intending to use), but right now he knows what must be done, I havent read up on it yet.
Currently I'm finishing off my dissertation for a week monday and have probably cut about half of the wood for bass cabs. Once my dissertation is in I'll have all my time to crack on with these speakers. A week monday I will have around 4 weeks until they must be completely finished... so lots to do.
Richard.
Cheers for the info. I've been looking into horns recently - am currently building the Edgar rectangular tractrix (JBL LE-5 driver). Am trying to work out the best way for me to build circular horns. Have cnc type cutting available for 2D stuff so can do stacked layers, but its very labour intensive. I like the idea of fibreglass moulding better
I believe the Avant Garde stuff is injection moulded - pretty expensive set up tooling I'd imagine.
Good luck with the rest of the project.
Rob.
I believe the Avant Garde stuff is injection moulded - pretty expensive set up tooling I'd imagine.
Good luck with the rest of the project.
Rob.
Yes the avantgarde stuff is injection moulded, crazy expensive tooling, but it probably lasts a long time as there are no crucial right-angles etc unlike small plastic toys etc (and I guess they're not making that many horns either comparitively)
My mould was built from layers of 'cellotex' which is used in roof insulation - Yellow foam stuff that wont turn to stodge from the resin fumes - just peel off the foil from the outside and glue the layers together. This can be easily shaped with a 'surform' (a bit like a cheese grater) to get an approximate shape. I built the layers around a dowel and then used a scraper turning on the dowel to get an almost perfect plaster shape (after layering up modroc on the foam). Cost me nearly 100GBP to make the plug, i think it was probably the best way to do it.
Richard.
My mould was built from layers of 'cellotex' which is used in roof insulation - Yellow foam stuff that wont turn to stodge from the resin fumes - just peel off the foil from the outside and glue the layers together. This can be easily shaped with a 'surform' (a bit like a cheese grater) to get an approximate shape. I built the layers around a dowel and then used a scraper turning on the dowel to get an almost perfect plaster shape (after layering up modroc on the foam). Cost me nearly 100GBP to make the plug, i think it was probably the best way to do it.
Richard.
Can anyone tell me what effect a longer phase plug will have in the front horns? Its the only thing that I'm not sure whether to do or not, I know alot of people use them in Oris horns. How does it affect the responce on + off axis?
If people think its worthwhile I'll order a pair from Planet10.
Richard.
If people think its worthwhile I'll order a pair from Planet10.
Richard.
Greets!
Phase plugs designed for a baffled FR driver won't be optimum for a horn loaded one and if there's any design math or rules-of-thumb, I'm not aware of them and I don't see how the math for compression driver phase plugs would be of any use, but then math isn't one of my strong suits.
For sure I think there's some performance gains to be had by using them, but the only way I know how to do it is by experimentation, and as its size increases, the throat area needs to increase to offset it, ergo the entire horn must grow too. Since Lowthers apparently require fairly large phase plugs, I assume this would apply to the FE206E also, but only one way to know for sure: http://audioprogress.free.fr/
GM
Phase plugs designed for a baffled FR driver won't be optimum for a horn loaded one and if there's any design math or rules-of-thumb, I'm not aware of them and I don't see how the math for compression driver phase plugs would be of any use, but then math isn't one of my strong suits.
For sure I think there's some performance gains to be had by using them, but the only way I know how to do it is by experimentation, and as its size increases, the throat area needs to increase to offset it, ergo the entire horn must grow too. Since Lowthers apparently require fairly large phase plugs, I assume this would apply to the FE206E also, but only one way to know for sure: http://audioprogress.free.fr/
GM
Hi everyone, sorry i havent got back about the issues with the pdf, it is A2. You could scale it to the right size in photoshop or similar.... I believe that profile is pretty much the same as an Oris 150.
Anyway.
Been very very busy since my last post. The project is in tomorrow, paperwork to do now. One speaker is completely finished, the other is a 'working prototype' right now (i.e. hasnt been polished and veneered yet), but will be finished for my degree show in 2 weeks time.
Went to Sevenoaks HiFi in Peterborough yesturday with the completely finished one to get an idea what people think. Attached is a picture at the shop with my speaker next to a Kef Reference 207 and a PMC OB1 - Please please let me know what you think, positive or negative, its really valuable to me for evaluation purposes.
Cheers, Richard.
Anyway.
Been very very busy since my last post. The project is in tomorrow, paperwork to do now. One speaker is completely finished, the other is a 'working prototype' right now (i.e. hasnt been polished and veneered yet), but will be finished for my degree show in 2 weeks time.
Went to Sevenoaks HiFi in Peterborough yesturday with the completely finished one to get an idea what people think. Attached is a picture at the shop with my speaker next to a Kef Reference 207 and a PMC OB1 - Please please let me know what you think, positive or negative, its really valuable to me for evaluation purposes.
Cheers, Richard.
Attachments
Stunning! Just in case I missed something and this is unfinished bass cabinet, the color does not work at all as is IMO with that attractive glossy pattern overlay. Needs to be red or blue, maybe orange or yellow as in hi-gloss shiney sports car colors IMO.
Have you thought about a dressy protector screen or other to protect the vulnerable woofer?
Again, very nice!
Have you thought about a dressy protector screen or other to protect the vulnerable woofer?
Again, very nice!
apart from the shiney black bits, the cabinet is veneered in a very high quality maple veneer, rich has done a great job. The photos really do not do them justice and they look great in real life, i think that having the whole thing painted- especially a bright colour, wouldnt work in real life. They are big enough as it is, the veneer helps them be a bit more subtle (if a huge great front horn can ever be subtle . . .) and a bright colour would be overkill i think.
As far as i know the woofer will get a grill and the horn will get a kind of "sock" that fits over the end made of stretchy grill cloth. The exposed woofer looks very cool though with the massive phase plug.
As far as i know the woofer will get a grill and the horn will get a kind of "sock" that fits over the end made of stretchy grill cloth. The exposed woofer looks very cool though with the massive phase plug.
Yes, I decided given they're so big that I didnt want them being too in your face. As part of my project the finish just gives a potential product end point. "Commercially" they would likely be availible in a wide range of finishes....
Hehe cheers, they're my project not Matts! - thanks for the comments though....
Matt is my friend here at loughborough university (so we know quite alot about each others work), we both do industrial design and are both doing some kind of speaker projects for our final year projects. Matts speakers are over here http://www.diyaudio.com/forums/showthread.php?s=&threadid=72387
Richard.
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