It is not a new project, it is not practical for cabinetmakers, but people asked me for info so I am opening dedicated thread for my horns.
Warning, I am not a horn “expert”, I did some modeling, but I took plans for these horns from the top of my head therefore the dimensions of horn may not be optimal for the driver used. Although I like the sound of Lowther drivers I can not recommend them because of materials that disintegrate after a few years and shoddy workmanship.
To calculate profile of the horn I used Hypex calculator, courtesy of James Melhuish. I have education in material technology so to build the horns I was able to design material with desired mechanical and acoustical characteristics. I used metal powder, polyester, fiberglass composite with micro boundaries of various densities. Because I wasn’t making a shiny toy for sale I could use an inexpensive male mold. I partially broke the mold during removal from finished horn and threw it away after one pair of horns was made. Each horn was made in one continuous process, no “stitches” etc.
Baffle rings and phase plugs are made from oak; compression chamber and horn material is custom composite, content of metal powder in composite is 60% of weight, content of metals in powder is 55%W, 40%Cu, 15% Pb.
Because my horn is not folded, to limit midrange output from the mouth, horn had to be filled with some wool.
Baffle ring diameter is 0.35m; CC volume is ~0.003m^3; throat surface 0.0075m^2; effective length is 3.5m; mouth surface is 0.8m^2; horn profile is Hypex with M=0.8;
Drivers are stripped and modified Lowther EX3.
Dimensions: W-1.3m, H-1.05m, D-1.8m; weight ~ 90kg each without supports.
The frequency response is excellent from 50 to 12.000Hz, below 50 it drops like a rock; it is minus 6dB at 45Hz, minus 16 at 40. Above 12k it slowly rolls of, but I do not hear it anyway.
I made the horns and all their parts at home using simple tools and inexpensive lathe. Total cost of materials and drivers was (7 years ago) about $2,000.
How does it sound? The horns, the system and room they are in are tuned for my ears and taste. I listen to classical, mostly chamber music. And to my ears the sound is lavish and detailed; the soundstage is big and deep. The voices sound natural, strings sound vibrant and brass sounds dynamic and real. My horns are not suitable for recordings mastered to compliment sound of less sensitive speakers. So a lot of pop music sounds too detailed, too edgy, with over contrasted artificial soundstage. I also use the room as my home theatre and movies sound really good.
The rest of the system:
DIY TT plinth with modified VPI platter and bearing and Teres drive
DIY Stojek Natrix 13 tonearm; Shelter 501 II; Cary PH-302
Philips SACD1000 or Marantz BD 7004
Moth s2A3
Room is DIY trapezoid with complex acoustic treatment.
Thanks for your attention,
Marek Stojek
Warning, I am not a horn “expert”, I did some modeling, but I took plans for these horns from the top of my head therefore the dimensions of horn may not be optimal for the driver used. Although I like the sound of Lowther drivers I can not recommend them because of materials that disintegrate after a few years and shoddy workmanship.
To calculate profile of the horn I used Hypex calculator, courtesy of James Melhuish. I have education in material technology so to build the horns I was able to design material with desired mechanical and acoustical characteristics. I used metal powder, polyester, fiberglass composite with micro boundaries of various densities. Because I wasn’t making a shiny toy for sale I could use an inexpensive male mold. I partially broke the mold during removal from finished horn and threw it away after one pair of horns was made. Each horn was made in one continuous process, no “stitches” etc.
Baffle rings and phase plugs are made from oak; compression chamber and horn material is custom composite, content of metal powder in composite is 60% of weight, content of metals in powder is 55%W, 40%Cu, 15% Pb.
Because my horn is not folded, to limit midrange output from the mouth, horn had to be filled with some wool.
Baffle ring diameter is 0.35m; CC volume is ~0.003m^3; throat surface 0.0075m^2; effective length is 3.5m; mouth surface is 0.8m^2; horn profile is Hypex with M=0.8;
Drivers are stripped and modified Lowther EX3.
Dimensions: W-1.3m, H-1.05m, D-1.8m; weight ~ 90kg each without supports.
The frequency response is excellent from 50 to 12.000Hz, below 50 it drops like a rock; it is minus 6dB at 45Hz, minus 16 at 40. Above 12k it slowly rolls of, but I do not hear it anyway.
I made the horns and all their parts at home using simple tools and inexpensive lathe. Total cost of materials and drivers was (7 years ago) about $2,000.
How does it sound? The horns, the system and room they are in are tuned for my ears and taste. I listen to classical, mostly chamber music. And to my ears the sound is lavish and detailed; the soundstage is big and deep. The voices sound natural, strings sound vibrant and brass sounds dynamic and real. My horns are not suitable for recordings mastered to compliment sound of less sensitive speakers. So a lot of pop music sounds too detailed, too edgy, with over contrasted artificial soundstage. I also use the room as my home theatre and movies sound really good.
The rest of the system:
DIY TT plinth with modified VPI platter and bearing and Teres drive
DIY Stojek Natrix 13 tonearm; Shelter 501 II; Cary PH-302
Philips SACD1000 or Marantz BD 7004
Moth s2A3
Room is DIY trapezoid with complex acoustic treatment.
Thanks for your attention,
Marek Stojek
Attachments
Last edited:
Hi Marek, absolutely stunning! I can imagine they have a fantastic image, with the very small baffle (and with the baffle a nice distance away from walls).
I agree that Lowthers (and AER's) are just fantastic on chamber music, especially with something like the right 2A3 or similar. They have a "palpable" almost 3D quality that I've never heard from any other driver. (The field coil Lowthers sound very different from the regular Lowthers.)
That's a very unusual phase plug. So did you make a "cut" to free the horn from the mold? It looks like it would be challenging given the twisty one-piece nature of the horn.
I'd love to hear more about how you fabricated the mold.
I agree that Lowthers (and AER's) are just fantastic on chamber music, especially with something like the right 2A3 or similar. They have a "palpable" almost 3D quality that I've never heard from any other driver. (The field coil Lowthers sound very different from the regular Lowthers.)
That's a very unusual phase plug. So did you make a "cut" to free the horn from the mold? It looks like it would be challenging given the twisty one-piece nature of the horn.
I'd love to hear more about how you fabricated the mold.
Thanks,
The only part of the mold I have kept is the compression chamber – first picture. I have described the mold here:
http://www.diyaudio.com/forums/full-range/109685-why-not-mdf-34.html
The only part of the mold I have kept is the compression chamber – first picture. I have described the mold here:
http://www.diyaudio.com/forums/full-range/109685-why-not-mdf-34.html
Attachments
The frequency response is excellent from 50 to 12.000Hz, below 50 it drops like a rock; it is minus 6dB at 45Hz, minus 16 at 40. Above 12k it slowly rolls of, but I do not hear it anyway.
could you post a fr response graph?
could you post a fr response graph?
Sorry the graphs you asked for are raw measurements and not fit for publication. Quoted measurements were taken in finished room with RS meter 1m in front of one horn with two horns playing Sine signals. The level was set 90dB at 1kHz.
If you like graphs I can show you room response where mike was in listening position. After I took that graph I added more absorbing panels. The front panels are behind the screen. Picture shows room before I changed it into a dark home theatre.
If you like graphs I can show you room response where mike was in listening position. After I took that graph I added more absorbing panels. The front panels are behind the screen. Picture shows room before I changed it into a dark home theatre.
Attachments
thanks for the graph, is 50 Hz enough? for most music it might be, but some will be missing lowest octaves, don't you agree? and especially movies require serious bass to be realistic
I admire your effort btw
I admire your effort btw
I don't know how deep my Mar-Kel70 goes but I think they work well for pretty much any music I play on them. Might sound a little thin to some kinds of rock but hey, it's a 4" full-range driver...
That's a serious set-up. Seriously cool too. Where's the tv or screen or whatever you use for movies?
LOL, I do not watch that kind of movies often, Valkyrie was an exception. The movies are recorded with overblown bass and my 50Hz are conservative and quite explosive.
The center image is excellent without center channel. I do not like surround sound effect, I like the sound to come from where the action is (on the screen).
The graph is the room response - the speaker response is different, it is on the plus side, between 50 and 70Hz. To get a speaker response graph I would have to bring the monster outside - which will never happen. Because of time delay in BLH and horn size the software I use (ETF 5) can not eliminate room influence.
The lowest fundamental frequency of cello is 65Hz, Piano plays lower, but low keys are seldom used. It’s not important for me that once in a blue moon few notes of double bass or pipe organ are represented only by higher harmonics.
Jimbro, look at the pictures in post #4, the projector is hanging from the ceiling.
The center image is excellent without center channel. I do not like surround sound effect, I like the sound to come from where the action is (on the screen).
The graph is the room response - the speaker response is different, it is on the plus side, between 50 and 70Hz. To get a speaker response graph I would have to bring the monster outside - which will never happen. Because of time delay in BLH and horn size the software I use (ETF 5) can not eliminate room influence.
The lowest fundamental frequency of cello is 65Hz, Piano plays lower, but low keys are seldom used. It’s not important for me that once in a blue moon few notes of double bass or pipe organ are represented only by higher harmonics.
Jimbro, look at the pictures in post #4, the projector is hanging from the ceiling.
I completely agree that surround sound effects are unnecassary for movies. Any sound from behind the head is distracting when the picture is upfront. Besides, those dolby prologic processors degrade sound. Two good channels is way better than five crappy channels.
On the other hand, I personaly like to have good bass extension below 30Hz, therefore I use subwoofers. Sound is way more realistic even for string quartet or small jazz group.
On the other hand, I personaly like to have good bass extension below 30Hz, therefore I use subwoofers. Sound is way more realistic even for string quartet or small jazz group.
I think I prefer having the sound from "the screen" when watching films too. And I really dislike the new 3D-stuff that is coming, just nonsense according to me.
It was a while ago that I heard a system capable of playing well down to 30 and below, so I don't really remember what it was like. But next time I go to a hifi-store I may have to try and see if it makes any difference.
After a few years of use, voice coil of one of my drivers started to scratch. The cone warped and in seventh year the cone surround cracked.
I watched You Tube videos how to repair Lowther drivers. I ordered new surrounds ($20 from Speaker Works). The surrounds did not match exactly but they were close enough and inexpensive. The moment I cut the old surround out, rotten spider fell apart and cone was hanging on two wires. I had to order a set of spiders and surrounds ($80 on eBay). The original installation of cone was crooked (picture 1) and my cone was warped so I decided to worry about centering of the coil later and installed the spider and surround without wedging the coil in the magnet. The original spider was glued all the way down on the former - which was good because I did not have to worry about depth or angle. Picture 2 shows remaining foam ring from the original spider. I unscrewed the wires and cleaned old foam from cone and basket. I supported the cone with a piece of 5mm thick plywood (picture 3) so the cone was at the correct level. I brushed the glue (supplied by speaker works) on all four surfaces and glued the spider on the cone and basket. After drying the glue for a couple of hours I flipped the basket and glued the surround. As expected after reinstallation the cone and former were still crooked. Fortunately position of coil in the magnet could be adjusted in every direction and angle could be corrected by shimming the magnet. Picture 4 shows leftover peace of original shim and extra washer Lowther used after they cross-threaded one of the screws.
The other driver is not scratching and surround is holding so I left it alone for now.
I strongly recommend staying away from this brand.
Marek
I watched You Tube videos how to repair Lowther drivers. I ordered new surrounds ($20 from Speaker Works). The surrounds did not match exactly but they were close enough and inexpensive. The moment I cut the old surround out, rotten spider fell apart and cone was hanging on two wires. I had to order a set of spiders and surrounds ($80 on eBay). The original installation of cone was crooked (picture 1) and my cone was warped so I decided to worry about centering of the coil later and installed the spider and surround without wedging the coil in the magnet. The original spider was glued all the way down on the former - which was good because I did not have to worry about depth or angle. Picture 2 shows remaining foam ring from the original spider. I unscrewed the wires and cleaned old foam from cone and basket. I supported the cone with a piece of 5mm thick plywood (picture 3) so the cone was at the correct level. I brushed the glue (supplied by speaker works) on all four surfaces and glued the spider on the cone and basket. After drying the glue for a couple of hours I flipped the basket and glued the surround. As expected after reinstallation the cone and former were still crooked. Fortunately position of coil in the magnet could be adjusted in every direction and angle could be corrected by shimming the magnet. Picture 4 shows leftover peace of original shim and extra washer Lowther used after they cross-threaded one of the screws.
The other driver is not scratching and surround is holding so I left it alone for now.
I strongly recommend staying away from this brand.
Marek
Attachments
Hi!
Marek - you've done well with your remounting but the secret is a special tool that ensures absolute regularity of the circle of the voice coil, giving maximum tolerance in the gap. Working with the cone downwards onto a table should ensure that the cone is exactly at right angles and centring will happen naturally with the spider fitted snugly in place.
In my experience, foams last 16 years. Bearing in mind their function is to suspend a cone effectively without mounting mass, they do quite well and no other 8 inch tweeter exists with which to represent a cymbal nor a violin nor a cello, and with all harmonics in phase.
Lowther is not a brand - it's an addiction.
On phase plugs, I don't like the modern phase plugs. I have cast from an original 1950s PM3 phaseplug which looks like a lightbulb. Rather than being a waveguide down the profile of the whizzer cone, it forms an expanding space as a horn. This takes away the agressiveness of a straight whizzer cone, loading and damping it well, and the roll back on the whizzer is then unnecessary. The rollback to my ears and direct comparison causes a confusion of sound, a lack of clarity, and guests who come to see me and hear Lowthers likewise prefer the straight whizzer.
http://i49.photobucket.com/albums/f298/furylovelolly/AG%20Ebay%20Shop/IMG_8401.jpg shows this clearly
(NOTE: this photograph may not be displaying proportions properly - click on the link to see the original)
and
http://i49.photobucket.com/albums/f298/furylovelolly/AG Ebay Shop/PM3tech.jpg
is the original advert.
Best wishes
David P
Marek - you've done well with your remounting but the secret is a special tool that ensures absolute regularity of the circle of the voice coil, giving maximum tolerance in the gap. Working with the cone downwards onto a table should ensure that the cone is exactly at right angles and centring will happen naturally with the spider fitted snugly in place.
In my experience, foams last 16 years. Bearing in mind their function is to suspend a cone effectively without mounting mass, they do quite well and no other 8 inch tweeter exists with which to represent a cymbal nor a violin nor a cello, and with all harmonics in phase.
Lowther is not a brand - it's an addiction.
On phase plugs, I don't like the modern phase plugs. I have cast from an original 1950s PM3 phaseplug which looks like a lightbulb. Rather than being a waveguide down the profile of the whizzer cone, it forms an expanding space as a horn. This takes away the agressiveness of a straight whizzer cone, loading and damping it well, and the roll back on the whizzer is then unnecessary. The rollback to my ears and direct comparison causes a confusion of sound, a lack of clarity, and guests who come to see me and hear Lowthers likewise prefer the straight whizzer.
http://i49.photobucket.com/albums/f298/furylovelolly/AG%20Ebay%20Shop/IMG_8401.jpg shows this clearly
(NOTE: this photograph may not be displaying proportions properly - click on the link to see the original)
and
http://i49.photobucket.com/albums/f298/furylovelolly/AG Ebay Shop/PM3tech.jpg
is the original advert.
Best wishes
David P
David,
You are right about regularity of circle of voice coil, thanks for reminding it.
I made my own tool to measure the inside diameter of the voice coil and I corrected the circle of the coil with my fingers avoiding scratching or stretching the coil. My tool is a very light thin piece of soft cedar shingle shaped like a trapezoid with almost parallel sides. When dropped into the coil part of it stays above the former. If in any spot the diameter of the coil is a hundredth of a mm bigger the tool will drop a few mm deeper. My tool and method apparently is far more precise than Lowthers’, but one needs precise fingers.
You are right about regularity of circle of voice coil, thanks for reminding it.
I made my own tool to measure the inside diameter of the voice coil and I corrected the circle of the coil with my fingers avoiding scratching or stretching the coil. My tool is a very light thin piece of soft cedar shingle shaped like a trapezoid with almost parallel sides. When dropped into the coil part of it stays above the former. If in any spot the diameter of the coil is a hundredth of a mm bigger the tool will drop a few mm deeper. My tool and method apparently is far more precise than Lowthers’, but one needs precise fingers.
- Status
- Not open for further replies.