Welcome to another installment of Help the Ijit! This is where experienced DIYers try to help the Ijit (me) build, dissuade him from doing so, or just roll their eyes and sigh "here he goes again!" I will leave it up to you to search for my past postings if you really give a ....
Ahem, anyway, today I propose a very simple project. I am fascinated by Linkwitz's designs and even considered building a Pluto a few years ago. I even ordered the drivers and during a brief bout of common sense, said "I'll never build this!" and sold the drivers. 🙂
Because I am a Bose 901 procurer, I have a stock of spare 901 (original CTS type) drivers and also a few current production similar FR drivers from Parts Express:
GRS 4FR-8 Full-Range 4-1/2" Speaker Pioneer Type A11EC80-02F 8 Ohm
I propose to use the "new" type (because T-S specs available) to design the current abomination.
I just want to make a pair of FR clones of the Pluto (LXmini, etc): I was at Lowe's last night, going to buy a 10' length of 4" PVC pipe ($11) when I saw an empty cardboard tube in the carpet section. It is about the same dimensions, and I got it free. It is certainly sturdy enough to support one driver on top 🙂
For base I decided on a 8x8x4" half-cinderblock ($1.77) into whose square center the cardboard tube conveniently fits. Wiring will probably be the indoor extension cord I bought unless I have other spare wire on hand.
In all a very simple project, no? But now come the design options: how long a pipe? Sealed end or make a QWTL?
Rationalization: this build aims to be a very inexpensive trial to allow me to get an idea of what a unique speaker design like the Pluto or LXmini might sound like. When I inevitably lose interest in the project (or fail to build it at all), the tube will become part of the playground for the guinea pig room.
Ahem, anyway, today I propose a very simple project. I am fascinated by Linkwitz's designs and even considered building a Pluto a few years ago. I even ordered the drivers and during a brief bout of common sense, said "I'll never build this!" and sold the drivers. 🙂
Because I am a Bose 901 procurer, I have a stock of spare 901 (original CTS type) drivers and also a few current production similar FR drivers from Parts Express:
GRS 4FR-8 Full-Range 4-1/2" Speaker Pioneer Type A11EC80-02F 8 Ohm
I propose to use the "new" type (because T-S specs available) to design the current abomination.
I just want to make a pair of FR clones of the Pluto (LXmini, etc): I was at Lowe's last night, going to buy a 10' length of 4" PVC pipe ($11) when I saw an empty cardboard tube in the carpet section. It is about the same dimensions, and I got it free. It is certainly sturdy enough to support one driver on top 🙂
For base I decided on a 8x8x4" half-cinderblock ($1.77) into whose square center the cardboard tube conveniently fits. Wiring will probably be the indoor extension cord I bought unless I have other spare wire on hand.
In all a very simple project, no? But now come the design options: how long a pipe? Sealed end or make a QWTL?
Rationalization: this build aims to be a very inexpensive trial to allow me to get an idea of what a unique speaker design like the Pluto or LXmini might sound like. When I inevitably lose interest in the project (or fail to build it at all), the tube will become part of the playground for the guinea pig room.
Very Kewl! I'm kinda in the same mode myself..
I have 2-8" coaxials and some 8" I.D. concrete form tubes that I plan to make a set of speakers out of this weekend. (Sealed using 3/4" plywood for the end caps)
Good Luck! I'll be following..
I have 2-8" coaxials and some 8" I.D. concrete form tubes that I plan to make a set of speakers out of this weekend. (Sealed using 3/4" plywood for the end caps)
Good Luck! I'll be following..
If i may suggest: Visaton FRS 5 X as replacement for the Aurasound 2 inch speaker? Will give you some (spl) headroom and the +- 800 Hz x-over point is no problem at all.
The Vifa TC6FD is also a very good 2in driver for this type of speaker at $10 ea.
Vifa TC6FD00-04 2" Full Range Paper Cone Woofer 4 Ohm
Or better yet, for $14 there is a newer 2.5in variant with 87dB sensitivity and smoother response, called the TC7FD04:
Tymphany TC7FD04-04 2-1/2" Full-Range Line Array Driver 4 Ohm
Vifa TC6FD00-04 2" Full Range Paper Cone Woofer 4 Ohm
Or better yet, for $14 there is a newer 2.5in variant with 87dB sensitivity and smoother response, called the TC7FD04:
Tymphany TC7FD04-04 2-1/2" Full-Range Line Array Driver 4 Ohm
Nice! I'll build a pair for the inevitable time that I move out of my current spacious apartment and into my retirement home, an Airstream trailer.
Taking advantage of a beatiful Thanksgiving day and no family (they're dead! -- or live far away) ... I did most of the assembly of the current speaker pair. Name? I was thinking something like "bug in a rug" because the cardboard tube's origin from carpeting, but I just got the idea: since my idea is a poor clone of one of Herr Linkowitz's pillar designs, why not the "polluto"? Actually, my cheap design is mostly recycled items: the tube as mentioned above, the stuffing is from two throw pillows from thrift shop ($1 each). The biggest pain in the a$$ is wiring stuff up. I had on hand some of the 5-way binding posts and what a nuisance. The outside I understand, I have seen this before. But the interior side has (per contact) two lock washers, two washers, and two nuts??? Are these designed for spade or ring lungs on the inside these days? Whatever happened to just soldering stuff 🙂
I had to rig a flat piece of wood (paint stirrer donor) for a facing for the darn binding post. I am starting to understand why me and many others just run the wires direct out of the cabinet 🙄
That I did -- sloppily as my moniker would imply. Did check continuity and stuff is buzzed or pretty close to 8 ohms when hooked up.
I was going to try at first as transmission line, but I decide that Siegfried probably knows best so they are sealed (well not yet).
Still not sure about a base. I've taken some photos and I'll post them. Or not.
I had to rig a flat piece of wood (paint stirrer donor) for a facing for the darn binding post. I am starting to understand why me and many others just run the wires direct out of the cabinet 🙄
That I did -- sloppily as my moniker would imply. Did check continuity and stuff is buzzed or pretty close to 8 ohms when hooked up.
I was going to try at first as transmission line, but I decide that Siegfried probably knows best so they are sealed (well not yet).
Still not sure about a base. I've taken some photos and I'll post them. Or not.
Here is a photo of the almost completed pair. My workshop here (toilet) is appropriate for the quality my creation. I like to use gorilla glue, but as you can see it has the problem of oozing. While not shown i assure you that the quality of my soldering work is equal to my adhesive skill. One innovation i tried with this pair was a pour in base of Gorilla Glue.
Lookin' Good! It's fun makin' sumptin' from nuthin'..
I've used Plaster of Paris to seal smaller tubes ends with. (The repair stuff that doesn't shrink) Adds base stability too. Plaster works good in bottoms of plastic buckets to stop the bottom from being a drum head..
My warm up to the 8" project. A couple of Folgers cans and a pair of Memphis 3.5" wrapped Burrito style in towels. Internal volume is almost perfect with a touch of cotton batting..
I've used Plaster of Paris to seal smaller tubes ends with. (The repair stuff that doesn't shrink) Adds base stability too. Plaster works good in bottoms of plastic buckets to stop the bottom from being a drum head..
My warm up to the 8" project. A couple of Folgers cans and a pair of Memphis 3.5" wrapped Burrito style in towels. Internal volume is almost perfect with a touch of cotton batting..
Use hot melt glue for stuff like this. No oozing and is clear. Sets fast and is cheaper than G glue which, IMO costs too much. Something is wrong when a bottle of G glue costs almost as much as a driver of more.
OK Mr. Smarty Pants, can you make a long tube out of your wondrous foam board 😛
You may have a point. I like Gorilla Glue because it does last a while, it's very strong and glues wood and almost anything else I've tried. And for my "who cares what it looks like?" prototyping, it adds an unpredictable flair 🙂
Even with its cost, a bottle of GG lasts me months and a few projects. Here are some of the things I've used it for (not all successful): patching a small hole in my concrete driveway, fabric glue a piece of leather onto the seat of work pants (works), fingernail repair (works better than Super glue, but can't touch nothing for about an hour), and even glueing wood and other speaker cabinet stuff together. Overall it seems as good as epoxy and less hassle, save for the expansion and foaming problem.
For the matter, not very costly, but at least in time cost, assembling the damned binding post should not take more time than all the other steps of assembling the speaker
Even though the tube was free, it may develop issues with coming undone. Obviously it is not designed to last, and was already separating on the inside. I have not decided how to (or if) I will finish each speaker. One option given the potential unraveling is to wrap the tube with decorative tabe or contact paper. Otherwise I will probably paint them with oil-based as recommended in another thread, instead of water based.
Of course for a better build you could use a PVC pipe or a real Sonotube (do they make them in smaller sizes?). If you had the materials on hand, an excellent base would be instead of Gorilla Glue, like the guy abovve did, pour in an inch of cement or similar. Even with no weight and my less than perfect cuts, each speaker will stand on the floor but like an attractive woman it has a high center of gravity
You may have a point. I like Gorilla Glue because it does last a while, it's very strong and glues wood and almost anything else I've tried. And for my "who cares what it looks like?" prototyping, it adds an unpredictable flair 🙂
Even with its cost, a bottle of GG lasts me months and a few projects. Here are some of the things I've used it for (not all successful): patching a small hole in my concrete driveway, fabric glue a piece of leather onto the seat of work pants (works), fingernail repair (works better than Super glue, but can't touch nothing for about an hour), and even glueing wood and other speaker cabinet stuff together. Overall it seems as good as epoxy and less hassle, save for the expansion and foaming problem.
For the matter, not very costly, but at least in time cost, assembling the damned binding post should not take more time than all the other steps of assembling the speaker
Even though the tube was free, it may develop issues with coming undone. Obviously it is not designed to last, and was already separating on the inside. I have not decided how to (or if) I will finish each speaker. One option given the potential unraveling is to wrap the tube with decorative tabe or contact paper. Otherwise I will probably paint them with oil-based as recommended in another thread, instead of water based.
Of course for a better build you could use a PVC pipe or a real Sonotube (do they make them in smaller sizes?). If you had the materials on hand, an excellent base would be instead of Gorilla Glue, like the guy abovve did, pour in an inch of cement or similar. Even with no weight and my less than perfect cuts, each speaker will stand on the floor but like an attractive woman it has a high center of gravity
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A few hours' listening in two different rooms...
And it sounds pretty good. Of course some of this is pride of ownership. When I was a kid I made a mini-Victrola by taking a straight pin and using a Dixie Cup for the "horn", it produced sound off a record but was not too hi-fi 🙂
Source is streaming Pandora and a few high bit rate mp3s. I haven't experienced the magical 3-D image or whatever yet but I will give it some time.
Meanwhile, in transit one of the drivers came partially loose. I retract anything I said about Gorilla Glue being strong 🙂
There are still some gaps to caulk too.
The design is interesting, and perhaps has been neglected? Perhaps I should give a transmission line a try. However, the sims looked pretty bad. How about an upright single folded "horn"? I know somebody else had speculated on this earlier...don't know if anything was actually built. Why couldn't one make essentially a up-facing horn? It would still be point source (for the highs) but with the added reinforcement and cancellation of the backwave.
And it sounds pretty good. Of course some of this is pride of ownership. When I was a kid I made a mini-Victrola by taking a straight pin and using a Dixie Cup for the "horn", it produced sound off a record but was not too hi-fi 🙂
Source is streaming Pandora and a few high bit rate mp3s. I haven't experienced the magical 3-D image or whatever yet but I will give it some time.
Meanwhile, in transit one of the drivers came partially loose. I retract anything I said about Gorilla Glue being strong 🙂
There are still some gaps to caulk too.
The design is interesting, and perhaps has been neglected? Perhaps I should give a transmission line a try. However, the sims looked pretty bad. How about an upright single folded "horn"? I know somebody else had speculated on this earlier...don't know if anything was actually built. Why couldn't one make essentially a up-facing horn? It would still be point source (for the highs) but with the added reinforcement and cancellation of the backwave.
Tonight score is a curb side 1997 Aiwa mini CD component system that according to the previous owner has a busted cd and dual cassette but everything else seems to work well and is suitable for driving my new speakers. Has green and red led buttons appropriate to the season. Also has the 5.1 speakers. I have no reason to hook them up. I have owned similar mini surround systems and the sound is OK considering the price. But tonight is free 😂
The honeymoon is over already 🙁
I heard (and confirmed with "PA Tone", an Android frequency generator app, that one channel has some distortion. I am suprised, since these drivers are nearly new and I haven't blasted them (yet). Memo to self: run a sine sweep of the driver BEFORE you have cemented and caulked it in place 😱
During the sine wave sweep last night, I was able to hear and see resonance in the column, even to the point where it was visibly rocking. Not quite the "Tacoma Narrows Bridge" (look up that video if you've never seen it) but probably could make the unit fall over if I let it go on. Even for cheap drivers, a hard fall can do bad things. I have lower tech methods to do that: bumping into one carelessly, one of the cats using it for a scratching post. 🙂
In addition to a bum driver, I need to get some kind of a base for these. Instead of the 8x8x4 block which seems overkill, I am going to look for a small paver and perhaps use caulk for the base.
In the meanwhile it is tolerable for most music. Caulking up my leaky GG seams seems to have made an improvement to the bass, or is it the super-duper-bass-enhancer, BBE, dreadful EQ presets and other trash found in the ancient Aiwa? (I think I have turned them off, but don't have a manual.) Free is free, and still I complain 🙂
I heard (and confirmed with "PA Tone", an Android frequency generator app, that one channel has some distortion. I am suprised, since these drivers are nearly new and I haven't blasted them (yet). Memo to self: run a sine sweep of the driver BEFORE you have cemented and caulked it in place 😱
During the sine wave sweep last night, I was able to hear and see resonance in the column, even to the point where it was visibly rocking. Not quite the "Tacoma Narrows Bridge" (look up that video if you've never seen it) but probably could make the unit fall over if I let it go on. Even for cheap drivers, a hard fall can do bad things. I have lower tech methods to do that: bumping into one carelessly, one of the cats using it for a scratching post. 🙂
In addition to a bum driver, I need to get some kind of a base for these. Instead of the 8x8x4 block which seems overkill, I am going to look for a small paver and perhaps use caulk for the base.
In the meanwhile it is tolerable for most music. Caulking up my leaky GG seams seems to have made an improvement to the bass, or is it the super-duper-bass-enhancer, BBE, dreadful EQ presets and other trash found in the ancient Aiwa? (I think I have turned them off, but don't have a manual.) Free is free, and still I complain 🙂
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Distortion may not be fault of driver - vibrations of the enclosure especially cardboard or foam core, even thin plywood contribute. Need to add bracing or mass damping to walls. Feel with your hands to see what is vibrating and fix it.
You are completely correct about the resonance and the need for more bracing and or mass loading. I noted vibration in both cabinets. On the other hand, the second unit is identical but audibly purer tone.
Or I can "accentuate the positive." It is not a problem of cabinet resonance, instead the unit is designed to be a line source at specific frequencies 🙄
1st pair working well, thinking about a QW version...
I got tired of the humming driver so replaced it with an identical one. Meanwhile, I decided I need whizzers so adapted the plastic cones from two unused ridiculous 2W LED (120V) bulbs I bought a while back. Painted both tubes blue (now they match my home exerior) and have 8x10" wooden base and foam feet for each cylinder. Other than perhaps sanding off some of my inevitably sloppy glue ooze and drips and some more paint, I pronounce them "done". They sound quite good, no EQ yet even.
But I'm thinking...thinking...why not a QW version that would give some more low end? The closest I've found is the "Poor Plumber's Pluto" here:
http://www.quarter-wave.com/Gallery/Poor_Plumbers_Pluto.jpg
Obviously this is a pretzel twist of The Master's Design, but it remains faithful to quality parts and PVC instead of my off-brand abomination 🙂
More to my ideas: why not a simple U-shaped speaker? One tube has the single driver, the 2nd is the far end of the TL. It remains a "pont source" and the only downside I see is the inevitable peaks and dips when you do this. Still, why not give it a try (after some time with Hornresp and maybe a better driver?)
I got tired of the humming driver so replaced it with an identical one. Meanwhile, I decided I need whizzers so adapted the plastic cones from two unused ridiculous 2W LED (120V) bulbs I bought a while back. Painted both tubes blue (now they match my home exerior) and have 8x10" wooden base and foam feet for each cylinder. Other than perhaps sanding off some of my inevitably sloppy glue ooze and drips and some more paint, I pronounce them "done". They sound quite good, no EQ yet even.
But I'm thinking...thinking...why not a QW version that would give some more low end? The closest I've found is the "Poor Plumber's Pluto" here:
http://www.quarter-wave.com/Gallery/Poor_Plumbers_Pluto.jpg
Obviously this is a pretzel twist of The Master's Design, but it remains faithful to quality parts and PVC instead of my off-brand abomination 🙂
More to my ideas: why not a simple U-shaped speaker? One tube has the single driver, the 2nd is the far end of the TL. It remains a "pont source" and the only downside I see is the inevitable peaks and dips when you do this. Still, why not give it a try (after some time with Hornresp and maybe a better driver?)
Did some modeling in Hornresp tonight and couldn't see what I have to lose by making my Polluto a QW pipe. It's already a pipe so with all the skill of an intoxicated Civil War field surgeon I made, that is "haphazardly gashed with my jigsaw", a port in the rear of the tube that is very approximately the right size. Also I tested and found one of my speakers is wired out of phase. Oops.
Based on my single sample, this seems like a simple, cheap, easy speaker to make. I'm surprised we don't see more examples of it. I guess people don't want a 3-foot high tube (or a pair) out in the middle of the room.
Based on my single sample, this seems like a simple, cheap, easy speaker to make. I'm surprised we don't see more examples of it. I guess people don't want a 3-foot high tube (or a pair) out in the middle of the room.
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