Hello there,
I wanted to build some speakers for places where they are likely to get damaged/abused, namely the lab that I work in at University and my living room. This means they should be cheap so that I am not constantly trying to manage the people around them to protect them.
It is obvious that the cheapest speakers will be a full range design as worthwhile tweeters push the price up considerably. Also the construction should be cheap, so I want to use foam core as the material, at 50p per A3 sheet it is hard to beat.
There are many drivers that people round here recommend for this kind of build, though most are from America, postage to the UK means it is actually cheaper to get mid-price drivers from Europe. Though I did some research and I have found a driver that I like for <10gbp here. I also get free postage from RS which helps the budget a bit.
I have simulated this and found that a 6L ported box tuned to 57Hz should be ideal. I am at work atm so I cannot post the sim graph, but this gives a nice 4db or so shelf below 120Hz, which could be seen as baffle step correction built in. Extension is down to about 50Hz, which I find to be acceptable for music without a subwoofer. This shelf also helps the fact that the drivers are not too sensitive, an extra 4db where most of the sound energy is should not be sniffed at.
The one potential flaw in the design is that the top end may be too muted to sound good. They advertise these drivers as full range upto 20KHz I think, hopefully the BMR design helps it where so many other FR fail.
All in all the speakers should be less than 25gbp per set and not be complete balls, well at least I hope that is the case. I will post back later today when I get to the cutting board!
I wanted to build some speakers for places where they are likely to get damaged/abused, namely the lab that I work in at University and my living room. This means they should be cheap so that I am not constantly trying to manage the people around them to protect them.
It is obvious that the cheapest speakers will be a full range design as worthwhile tweeters push the price up considerably. Also the construction should be cheap, so I want to use foam core as the material, at 50p per A3 sheet it is hard to beat.
There are many drivers that people round here recommend for this kind of build, though most are from America, postage to the UK means it is actually cheaper to get mid-price drivers from Europe. Though I did some research and I have found a driver that I like for <10gbp here. I also get free postage from RS which helps the budget a bit.
I have simulated this and found that a 6L ported box tuned to 57Hz should be ideal. I am at work atm so I cannot post the sim graph, but this gives a nice 4db or so shelf below 120Hz, which could be seen as baffle step correction built in. Extension is down to about 50Hz, which I find to be acceptable for music without a subwoofer. This shelf also helps the fact that the drivers are not too sensitive, an extra 4db where most of the sound energy is should not be sniffed at.
The one potential flaw in the design is that the top end may be too muted to sound good. They advertise these drivers as full range upto 20KHz I think, hopefully the BMR design helps it where so many other FR fail.
All in all the speakers should be less than 25gbp per set and not be complete balls, well at least I hope that is the case. I will post back later today when I get to the cutting board!
Hi Polop,
I own several of these Chassis and test them in different enclosure.
At the moment i have putted them in a pipe -> http://www.hellweg.de/out/pictures/generated/product/1/665_665_75/156302_marley_htbogen_01.png
I build a TML with two drivers in this pipe and actually i have a driver in a 90° pipe with a lot of wool for my kitchenradio. They work really nice and can be driven with a simple Tripath-amp. Your ported design is nice and will work very well on them.
If you want some bass then take a aurasound ns-3.
You will get a really small box with nice sound IMHO!
I want to design for myself a surroundsystem with these drivers. They are really nice for movies!
I own several of these Chassis and test them in different enclosure.
At the moment i have putted them in a pipe -> http://www.hellweg.de/out/pictures/generated/product/1/665_665_75/156302_marley_htbogen_01.png
I build a TML with two drivers in this pipe and actually i have a driver in a 90° pipe with a lot of wool for my kitchenradio. They work really nice and can be driven with a simple Tripath-amp. Your ported design is nice and will work very well on them.
If you want some bass then take a aurasound ns-3.
You will get a really small box with nice sound IMHO!
I want to design for myself a surroundsystem with these drivers. They are really nice for movies!
Try this design - uses $12 Vifa TC9FD and low cost (in US) foam core. In Europe, you can use alternative materials (triple ply corrugated cardboard) or thin plywood. Also works great with a $19 Faital Pro 3FE25. Very easy and quick to make, costs almost nothing, lightweight, sounds great...
http://www.diyaudio.com/forums/full-range/239338-mini-karlsonator-0-53x-dual-tc9fds-16.html#post3722988
Measured response with 3FE25:
http://www.diyaudio.com/forums/full-range/239338-mini-karlsonator-0-53x-dual-tc9fds-16.html#post3722988
Measured response with 3FE25:
Ah I see. I don't think that will be necessary, I plan on just having more of these speakers untill it is loud enough that people do not need to turn it up . I am more worried in general about protecting them physically from flailing arms, though if they are cheap enough this is less of a concern.
. I am more worried in general about protecting them physically from flailing arms, though if they are cheap enough this is less of a concern.Hello there,
So I built one of them.
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Something seems wrong. The simulations said that there would be extra bass between 50-150Hz, though the bass range seems very weak. At 55Hz I measure it to be many decibels down, it is certainly noticeable.
Here is the sim I mentioned earlier, the pink one is the sim of the speedsters by undefinition, which are my reference speakers. both at 20W.
I have tried with no stuffing, lots of stuffing and somewhere about half way and it all sounds about the same to me.
The port is twin 7cm by 1cm by 17.5cm long. tuning the box to 57Hz box volume about 6.5L.
Any ideas.
So I built one of them.
Something seems wrong. The simulations said that there would be extra bass between 50-150Hz, though the bass range seems very weak. At 55Hz I measure it to be many decibels down, it is certainly noticeable.
Here is the sim I mentioned earlier, the pink one is the sim of the speedsters by undefinition, which are my reference speakers. both at 20W.
I have tried with no stuffing, lots of stuffing and somewhere about half way and it all sounds about the same to me.
The port is twin 7cm by 1cm by 17.5cm long. tuning the box to 57Hz box volume about 6.5L.
Any ideas.
What driver is that? You do have access to foam core and hot melt glue.
You may be experiencing baffle step loss and your mids and highs are playing about 5dB to 6dB louder. You need to either EQ the highs from say 800Hz on up by -6dB and see if that helps. Or add a BSC circuit with about a 0.8mH coil and a 6ohm resistor in parallel between amp and driver positive terminal.
You may be experiencing baffle step loss and your mids and highs are playing about 5dB to 6dB louder. You need to either EQ the highs from say 800Hz on up by -6dB and see if that helps. Or add a BSC circuit with about a 0.8mH coil and a 6ohm resistor in parallel between amp and driver positive terminal.
Morning
Here is the thread for the Vifantastic (Vifantastisch), uses the great bargain driver from Vifa/Peerless in a flat wall cabinet (kind of like a thick picture).
Easy to build an works perfect without an bsc or eq! Decent bass output thanks to the tml.
AND PLEASE NO FOAMCORE BOARD STUFF!!!!
imho that material is much too soft / bendable -> the walls of the tml line vibrate and resonate -> "absorbing" bass (energy). Contraproductive!
At least the front should be plywood.
Here you can get the Vifa 9BN 119/8, a nice shopo to buy full range drivers.
If you have questions regardibg the build feel free to ask.
Regards from Germany
Here is the thread for the Vifantastic (Vifantastisch), uses the great bargain driver from Vifa/Peerless in a flat wall cabinet (kind of like a thick picture).
Easy to build an works perfect without an bsc or eq! Decent bass output thanks to the tml.
AND PLEASE NO FOAMCORE BOARD STUFF!!!!
imho that material is much too soft / bendable -> the walls of the tml line vibrate and resonate -> "absorbing" bass (energy). Contraproductive!
At least the front should be plywood.
Here you can get the Vifa 9BN 119/8, a nice shopo to buy full range drivers.
If you have questions regardibg the build feel free to ask.
Regards from Germany
I have a couple of ideas to why it might not be performing as per the calculations.
1)I did not do any internal bracing of the material, which I think will be ruining the bass performance.
2) The slot port will behave non-ideally due to the thin aspect ratio. Perhaps adding too much damping to the system.
3) I have become used to listening to fantastic speakers, so these are bound to not sound up to scratch.
I think that it is unlikely to be a baffle step issue due to the rising response of the simulation, this should easily account for that. I think I will make another box, with much more bracing and a round port that will offer less drag. I like the suggestions, though I will stick with these drivers till I work out why the sims are not lining up. As even the vifa ones are from overseas for me, adding to the expense/waiting/uncertainty. These drivers are cheap with free next day delivery to the UK, I want to try my best to get them to work before moving on.
Incase it helps motivate the discussion, I also intend the speaker to be used as a bargain basement build for students to build as an extension after a PCB design course I will be teaching, where we build a chipamp with various filters.
1)I did not do any internal bracing of the material, which I think will be ruining the bass performance.
2) The slot port will behave non-ideally due to the thin aspect ratio. Perhaps adding too much damping to the system.
3) I have become used to listening to fantastic speakers, so these are bound to not sound up to scratch.
I think that it is unlikely to be a baffle step issue due to the rising response of the simulation, this should easily account for that. I think I will make another box, with much more bracing and a round port that will offer less drag. I like the suggestions, though I will stick with these drivers till I work out why the sims are not lining up. As even the vifa ones are from overseas for me, adding to the expense/waiting/uncertainty. These drivers are cheap with free next day delivery to the UK, I want to try my best to get them to work before moving on.
Incase it helps motivate the discussion, I also intend the speaker to be used as a bargain basement build for students to build as an extension after a PCB design course I will be teaching, where we build a chipamp with various filters.
Can this help regarding baffle step see picture one where box dimension is guessed by eye, at picture two driver is offset for nicer curves. The tool used is Jeff Bagby free for private Excel simulator which also is able to show room plots, here link excel file software.
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I have never seen a properly tuned bass reflex with rising bass response. Your ears are telling you otherwise that the bass is thin.
Any Ideas to why the sim would not line up? The rising response seems to come from the addition of the cone resonance and the box resonance.
For your driver get this plot 4th order vented box
20w input
6,5 liter box
Tuned 57Hz
2 ports 1 x 7 cm length 16,9 cm
My program warns about min. recommended vent should be 0,0017 Sg. meters, and the two 1 x 7 cm length 16,9 cm gives 0,0014 Sg. meters.
Have no technical knowledge the warning about vent area other than maybe something about pressure/flow/resonance capacity in the vent, maybe xrk971 have and pop in.
If you want keep that particular tuning maybe better a rectangular baffle then place port on the longest dimension, my program says a tube dia. 50mm length 24,4cm gives 0,00196 Sq. meter vent area at your 57Hz preferred tuning.
From simulation post 15 see you get a on axis -6dB baffle step decreasing response starting 750Hz downwards, the ~3dB boost at 100Hz from the vent tuning sits in a frequency area where typical boundery such outs exist, so expect some of the boost is canceled by that effect. Try the excel file linked at post 15 to see baffle step and boundary effect at various location placement of box.
EDIT: Think as xrk971 mention, you need correction somewhere for baffle step loss be it EQ or passive filter.
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Try the FRS8 from RS Components
Was struggling to find an affordable driver in the UK too..
Based on xrk971's suggestion the FRS8 is a drop in replacement for the tc9fds (wasn't able to find cheap supplier the Faital Pro 3FE25)
You can get 2 for £22.72 (with shipping and VAT) from RS Components
Where are you sourcing your foamcore from?
I'm planning on using double wall corrugated cardboard cut at RazorLab. If you can get into London, you can pick-up in person, saving shipping costs
Was struggling to find an affordable driver in the UK too..
Based on xrk971's suggestion the FRS8 is a drop in replacement for the tc9fds (wasn't able to find cheap supplier the Faital Pro 3FE25)
You can get 2 for £22.72 (with shipping and VAT) from RS Components
Where are you sourcing your foamcore from?
I'm planning on using double wall corrugated cardboard cut at RazorLab. If you can get into London, you can pick-up in person, saving shipping costs
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