I am running the Tech club at a local high school and the idea of building a stereo has come up. I am a fairly resourcefull person but my experience with soldering and circuitry is limited. I want to help point the students to a simple straightforward project that they can complete at home with help at school. I have never built a speaker before.
I purchased a Sonic T-Amp and have been fairly impressed by it (Though I din't have any really efficient speakers to try it on). It has a great price point and seems fairly easy to mod (atleast putting it in a different box with different connectors...) This seems like a good starting point. I don't mind the head phone jack connector since most students will have a mp3 player, cd walkman or computer to hook it to.
For a speaker I am looking for something that can be done simply for under $100 of parts...
The Fostex full-range drivers seem an easy way to go. It means we wouldn't have to mess with a crossover atleast. I would like the finished project to be bookshelf sized and the port to be on the front so it can be placed against a wall.
How do I work out how much volume the fostex drivers need? Is putting a single 4.5" driver like the FE126E in a bookshelf sized box going to produce enough bass? I could step up the 6.5" but it seems like the box would need to get bigger, and the 6.5" is pushing the price range.
Would a 2 way system be cheaper and more compact... could it still be as sensitive even build cheap. Is there an extremely simple way to build or buy a crossover... I also have access to a computer and microphone but not much more equipment than that for analysis.
I am thinking of using plywood or wood for the 1st iterations... They seem cheaper and easier to work with (especially to finish) though probably not as good as mdf.
Any advice is greatly appreciated. My most important question is how do I work out the volume needed for a given driver.
- Mountaingoat
I purchased a Sonic T-Amp and have been fairly impressed by it (Though I din't have any really efficient speakers to try it on). It has a great price point and seems fairly easy to mod (atleast putting it in a different box with different connectors...) This seems like a good starting point. I don't mind the head phone jack connector since most students will have a mp3 player, cd walkman or computer to hook it to.
For a speaker I am looking for something that can be done simply for under $100 of parts...
The Fostex full-range drivers seem an easy way to go. It means we wouldn't have to mess with a crossover atleast. I would like the finished project to be bookshelf sized and the port to be on the front so it can be placed against a wall.
How do I work out how much volume the fostex drivers need? Is putting a single 4.5" driver like the FE126E in a bookshelf sized box going to produce enough bass? I could step up the 6.5" but it seems like the box would need to get bigger, and the 6.5" is pushing the price range.
Would a 2 way system be cheaper and more compact... could it still be as sensitive even build cheap. Is there an extremely simple way to build or buy a crossover... I also have access to a computer and microphone but not much more equipment than that for analysis.
I am thinking of using plywood or wood for the 1st iterations... They seem cheaper and easier to work with (especially to finish) though probably not as good as mdf.
Any advice is greatly appreciated. My most important question is how do I work out the volume needed for a given driver.
- Mountaingoat
I'm not the most experienced member here so take what I say with a bit of salt.
Depends on the specific driver and how much you can give it. Download WinISD and play with it a bit to get a feeling for how each driver will respond in different sized enclosures.
According to the optimal plot for the FE126's you mention, the ideal bass reflex is around .5 cubic feet
Depends on what you mean by enough bass.
Some people are happy with the bass a fullrange driver can output in a small box but quite a few aren't. That's why the build horns and transmission lines or use subwoofers. Again, play around with the specs in WinISD to see if you can get a specific combination that has enough bass for you. (My guess is you will probably be okay with it... so long as you don't want to rock the floor!)
According to WinISD's optimal plot the 126 is -3dB at 87 Hz... Which is a little high IMHO. In a little bigger box (around .7 cu ft) with a higher tuning frequency (65 Hz) you can get the -3dB point down to 66 Hz which seems a little more reasonable but doing this makes the speaker less linear. (Use WinISD to plot the two graphs and you'll see what I mean)
www.partsexpress.com can hook you up with pre-built crossovers... though if you have any soldering skills they aren't hard to do.
You'll see a hundred different arguments for or against different materials. It seems like most people prefer good quality plywood to MDF... but I could be wrong.
Edit: Almost forgot here's some links to plans that are pretty similar to what you are looking for:
http://home.hetnet.nl/~geenius/Solo103.html
http://www.vikash.info/audio/W3-871S/
Depends on the specific driver and how much you can give it. Download WinISD and play with it a bit to get a feeling for how each driver will respond in different sized enclosures.
According to the optimal plot for the FE126's you mention, the ideal bass reflex is around .5 cubic feet
Depends on what you mean by enough bass.
Some people are happy with the bass a fullrange driver can output in a small box but quite a few aren't. That's why the build horns and transmission lines or use subwoofers. Again, play around with the specs in WinISD to see if you can get a specific combination that has enough bass for you. (My guess is you will probably be okay with it... so long as you don't want to rock the floor!)According to WinISD's optimal plot the 126 is -3dB at 87 Hz... Which is a little high IMHO. In a little bigger box (around .7 cu ft) with a higher tuning frequency (65 Hz) you can get the -3dB point down to 66 Hz which seems a little more reasonable but doing this makes the speaker less linear. (Use WinISD to plot the two graphs and you'll see what I mean)
www.partsexpress.com can hook you up with pre-built crossovers... though if you have any soldering skills they aren't hard to do.
You'll see a hundred different arguments for or against different materials. It seems like most people prefer good quality plywood to MDF... but I could be wrong.
Edit: Almost forgot here's some links to plans that are pretty similar to what you are looking for:
http://home.hetnet.nl/~geenius/Solo103.html
http://www.vikash.info/audio/W3-871S/
Making your own first and second order crossovers.
You can make your own crossovers and even go so far as to buy magnet wire off Ebay and wind your own inductors. There can be savings here at the thicker gauges for low DCR if you can measure inductance. Designing good crossovers is involved and can end up costing quite a bit more too if your not carefull.
Making the speakers smaller will entail a loss of efficiency and/or low end extension.
The FE126 has a low q and really needs a horn to make bass. Id suggest a folded TL using the FE 127 for a compact affordable reasonably efficient speaker with some bass.
This thread has some suitable suggestions.
You can make your own crossovers and even go so far as to buy magnet wire off Ebay and wind your own inductors. There can be savings here at the thicker gauges for low DCR if you can measure inductance. Designing good crossovers is involved and can end up costing quite a bit more too if your not carefull.
Making the speakers smaller will entail a loss of efficiency and/or low end extension.
The FE126 has a low q and really needs a horn to make bass. Id suggest a folded TL using the FE 127 for a compact affordable reasonably efficient speaker with some bass.
This thread has some suitable suggestions.
http://ratch-h.com/tweak.html
Many of these projects use a 4" speaker called the NSB. Cost $.49(thats 49 cents) each and is a great speaker for group projects.
http://www.partsexpress.com/projectshowcase/nsb/nsb2.htm
Many of these projects use a 4" speaker called the NSB. Cost $.49(thats 49 cents) each and is a great speaker for group projects.
http://www.partsexpress.com/projectshowcase/nsb/nsb2.htm
Another driver to conder might be the new 4" Tang Band. Could be quite easy to work with...
http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=264-846
http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=264-846
Thanks for the help!
Wow! I am amazed at all of the fast and helpful responses!
You have given me many great ideas and pointers...
A few thoughts:
The recommendation of:
http://ratch-h.com/tweak.html
was great, fun to check out yourself...
I am going to buy a few of the NSB drivers... for 49c you can't go wrong... can even cut one open to show the students how it ticks... I plan to by a few cheap tweeters(around $1) as well just to play with... This will give us something cheap to mess with and then tear apart and rebuild without feeling bad.
http://www.zaphaudio.com/
Had a lot of great and cheap speaker designs... A couple of good options... 3 or 4 for under $100 of parts
The crossovers don't seem so hard if I keep them simple and am not that picky. I don't expect the first Generation to sound that good... We'll get more technical and precise for the second gen...
I am thinking of building for myself around the fostex FE167E their standard bass reflex box... and maybe adding a FT17H tweeter with just a simple capacitor:
http://www.fostexinternational.com/docs/speaker_comp/pdf/recom_enclose/167e_enclrev.pdf
This seems a relatively good first project for myself though the drivers aren't quite so cheap and should yield a very sensitive bookself style speaker to pair with a sonic impact t-amp... Not much bass to speak of but I think everything else is fine... should approximate an Omega Grande 6 (though I've never heard one and they don't seem to be making them anymore):
http://www.responseaudio.com/omega.htm
I've heard good things about the FT17H tweeter and the FE167E... though the box is probably not the best for bass, I want it to be small and portable (I may set this up at outdoor festivals)... Any thoughts on how this might work?
Now I just got to convince the shop teacher to let me have access to the wood shop.
Wow! I am amazed at all of the fast and helpful responses!
You have given me many great ideas and pointers...
A few thoughts:
The recommendation of:
http://ratch-h.com/tweak.html
was great, fun to check out yourself...
I am going to buy a few of the NSB drivers... for 49c you can't go wrong... can even cut one open to show the students how it ticks... I plan to by a few cheap tweeters(around $1) as well just to play with... This will give us something cheap to mess with and then tear apart and rebuild without feeling bad.
http://www.zaphaudio.com/
Had a lot of great and cheap speaker designs... A couple of good options... 3 or 4 for under $100 of parts
The crossovers don't seem so hard if I keep them simple and am not that picky. I don't expect the first Generation to sound that good... We'll get more technical and precise for the second gen...
I am thinking of building for myself around the fostex FE167E their standard bass reflex box... and maybe adding a FT17H tweeter with just a simple capacitor:
http://www.fostexinternational.com/docs/speaker_comp/pdf/recom_enclose/167e_enclrev.pdf
This seems a relatively good first project for myself though the drivers aren't quite so cheap and should yield a very sensitive bookself style speaker to pair with a sonic impact t-amp... Not much bass to speak of but I think everything else is fine... should approximate an Omega Grande 6 (though I've never heard one and they don't seem to be making them anymore):
http://www.responseaudio.com/omega.htm
I've heard good things about the FT17H tweeter and the FE167E... though the box is probably not the best for bass, I want it to be small and portable (I may set this up at outdoor festivals)... Any thoughts on how this might work?
Now I just got to convince the shop teacher to let me have access to the wood shop.
I wish I had a club like that at my school.
I'm 17
There are tons of things that would be great inexpensive projects for your students.
I think using a cheap driver to cut open and show how it works is a great idea. Also to add to that you may go toHow stuff works.com
Are the student's paying for the drivers?
Some variety would be nice instead of everyone creating the same enclosure design.
If using the Sonic T amp you may want to consider using 4 ohm drivers. TB w4-1052sa. Those 4" Tang Bands have good low end extension for $22.
Here is my project using the Fostex FE127 This also includes GM's transmission line design. If some of your students are up to the challenge there are many other enclosures online too including different horns. This is also true for the smaller fostex drivers too, which again are less expensive.
If you want efficient drivers with some bass you can try Audio Nirvana their 6.5" is $98/pair.
Good luck,
Josh
I'm 17
There are tons of things that would be great inexpensive projects for your students.
I think using a cheap driver to cut open and show how it works is a great idea. Also to add to that you may go toHow stuff works.com
Are the student's paying for the drivers?
Some variety would be nice instead of everyone creating the same enclosure design.
If using the Sonic T amp you may want to consider using 4 ohm drivers. TB w4-1052sa. Those 4" Tang Bands have good low end extension for $22.
Here is my project using the Fostex FE127 This also includes GM's transmission line design. If some of your students are up to the challenge there are many other enclosures online too including different horns. This is also true for the smaller fostex drivers too, which again are less expensive.
If you want efficient drivers with some bass you can try Audio Nirvana their 6.5" is $98/pair.
Good luck,
Josh
Since I notice your affinity for Omega... here's a theoretical plan I drew up as a copy of their Minuet speaker which uses the rather intrigueing TB w4-1052sa that edjosh23 mentions. Basically it is the same as the Minuet but a bit bigger (for a touch lower bass) and (of course) without any magic dampening or supports that they use in theirs.
I've never built this design but it simulates well and could be a fun one to build.
I don't know if you're interested, but there are a several somewhat simple Class-D DIY amp kits floating around... If your students are interested in a follow-up project, I'd say one of these would be ideal. The easiest one would probably be the 41Hz Amp 6: http://www.41hz.com/ .
Its great to offer something like this at a high-school.... Heck, I would have loved it if my college or my grad school had offered something like this too!
I've never built this design but it simulates well and could be a fun one to build.
I don't know if you're interested, but there are a several somewhat simple Class-D DIY amp kits floating around... If your students are interested in a follow-up project, I'd say one of these would be ideal. The easiest one would probably be the 41Hz Amp 6: http://www.41hz.com/ .
Its great to offer something like this at a high-school.... Heck, I would have loved it if my college or my grad school had offered something like this too!
Attachments
Re: Thanks for the help!
I can't argue with the Frugal-phile(tm) approach. Make sure you look up Mark McKenzie's NSB mods. For budget tweeters it is hard to beat the little ApexJr Ts (diyAudio price is 2 for $1).
For more money i'd suggest the Aura NS3, and Fostex FE103/107 or FE127 (these are a lot easier to make work in simplier boxes). Pushing right to the edge of your budget the CSS WR125 mates nicely with the above mentioned tweeter (i was just tweaking such a combo tonite).
For anything more than computer speakers the NS3s & the WR125s would probably stress the Sonic Impact. A still easy, but more ambitious project with soldering required would be some BrianGT gain-clones.
For the FE167 the Bob Brines FT1600 ML-TL is well worth considering -- it is a favorite of the local crowd. Listen to them full-range before deciding if you really need a tweeter. I'd guess a suitable cap XO for the FT17 to the 167 would "officially be above 15k (higher if you listen on axis)
dave
mountaingoat said:
I can't argue with the Frugal-phile(tm) approach. Make sure you look up Mark McKenzie's NSB mods. For budget tweeters it is hard to beat the little ApexJr Ts (diyAudio price is 2 for $1).
For more money i'd suggest the Aura NS3, and Fostex FE103/107 or FE127 (these are a lot easier to make work in simplier boxes). Pushing right to the edge of your budget the CSS WR125 mates nicely with the above mentioned tweeter (i was just tweaking such a combo tonite).
For anything more than computer speakers the NS3s & the WR125s would probably stress the Sonic Impact. A still easy, but more ambitious project with soldering required would be some BrianGT gain-clones.
For the FE167 the Bob Brines FT1600 ML-TL is well worth considering -- it is a favorite of the local crowd. Listen to them full-range before deciding if you really need a tweeter. I'd guess a suitable cap XO for the FT17 to the 167 would "officially be above 15k (higher if you listen on axis)
dave
Seconding FT1600, Brines also offers a FE167 BR.
Try the T-Amp using a 12V computer supply, or regulated 13.8V CB type supply. Put a resistor or the 5V rail if using computer supply.
Ive been looking all over for information on the Apexjr tweeters and havent had much luck, even the most basic of info like Fs etc would help.
Try the T-Amp using a 12V computer supply, or regulated 13.8V CB type supply. Put a resistor or the 5V rail if using computer supply.
Ive been looking all over for information on the Apexjr tweeters and havent had much luck, even the most basic of info like Fs etc would help.
mountaingoat:
Two issues you have to be careful about when converting the SI5066 to a headphone amp:
1) Most headphones wire left and right to a common ground. I don't know how most headphone amps handle this situation, but I'm quite sure that the 5066 is not equipped to handle it. You can only use headphones if you rewire them for separate ground (3 wire to 4 wire).
2) The Tripath based amps are sensitive to correct impedence matching. The 5066 is optimized for a 8 ohm load, but most headphones offer much higher impedence. The danger here is that the amp will emphasize the higher frequencies and drop out the bottom end.
I can confirm this with my personal experience. Over the weekend I rewired my AKG 141 headphones (55 Ohm impedence) and plugged them in. The result was horribly bright. Luckily there is a solution. You can simply hang a resistor over each pair of terminals (in parallel) that fakes out the amp. It will see the impedence of your resistor (optimally 8 ohms) and put out a correct frequency balance. You do waste some power this way, but who needs power when driving headphones?
Since 8 ohm resistors rated at 10 watts are not stocked at my local Radio Shack (and I'm not patient enough to wait for mail order), I substituted 10 ohm resistors and they work fine.
A full discussion of these issues: http://www6.head-fi.org/forums/showthread.php?t=87285
Two issues you have to be careful about when converting the SI5066 to a headphone amp:
1) Most headphones wire left and right to a common ground. I don't know how most headphone amps handle this situation, but I'm quite sure that the 5066 is not equipped to handle it. You can only use headphones if you rewire them for separate ground (3 wire to 4 wire).
2) The Tripath based amps are sensitive to correct impedence matching. The 5066 is optimized for a 8 ohm load, but most headphones offer much higher impedence. The danger here is that the amp will emphasize the higher frequencies and drop out the bottom end.
I can confirm this with my personal experience. Over the weekend I rewired my AKG 141 headphones (55 Ohm impedence) and plugged them in. The result was horribly bright. Luckily there is a solution. You can simply hang a resistor over each pair of terminals (in parallel) that fakes out the amp. It will see the impedence of your resistor (optimally 8 ohms) and put out a correct frequency balance. You do waste some power this way, but who needs power when driving headphones?
Since 8 ohm resistors rated at 10 watts are not stocked at my local Radio Shack (and I'm not patient enough to wait for mail order), I substituted 10 ohm resistors and they work fine.
A full discussion of these issues: http://www6.head-fi.org/forums/showthread.php?t=87285
Ive been thinking about an NSB line array as a way to get alot out of an SI amp.
18 NSBs wired in 6 paralled groups of 3 NSBs in series (4 ohms) + 36 Apexjr tweeters wired in 6 groups of 6 (6 ohms?). Crossover is second order Linkwitz/Riley at ~5,000hz. Is this too low, Im kinda worried about combing?
Driver cost: $54 + shipping.
Crossover using PE parts:
High pass: 027-416 Dayton 2.7uF met poly cap. 255-406 Jantzen 15 gauge .39 mH air core inductor.
Low pass: 027-421 Dayton 4.0uF met poly cap. 255-402 Jantzen 15 gauge .25mH air core inductor.
Crossover cost: $24.42 + shipping.
Any comments would be appreciated, Im thinking about building a similar setup with more tweeters and different wiring.
18 NSBs wired in 6 paralled groups of 3 NSBs in series (4 ohms) + 36 Apexjr tweeters wired in 6 groups of 6 (6 ohms?). Crossover is second order Linkwitz/Riley at ~5,000hz. Is this too low, Im kinda worried about combing?
Driver cost: $54 + shipping.
Crossover using PE parts:
High pass: 027-416 Dayton 2.7uF met poly cap. 255-406 Jantzen 15 gauge .39 mH air core inductor.
Low pass: 027-421 Dayton 4.0uF met poly cap. 255-402 Jantzen 15 gauge .25mH air core inductor.
Crossover cost: $24.42 + shipping.
Any comments would be appreciated, Im thinking about building a similar setup with more tweeters and different wiring.
edjosh23:
I totally misunderstood. Yes, the input of the SI5066 is a stereo mini jack, commonly used for headphone output. My post above assumed that part of the project might be to add a headphone connector to the amp when it is being re-housed. I see now that wasn't what mountaingoat was saying.
Randy
I totally misunderstood. Yes, the input of the SI5066 is a stereo mini jack, commonly used for headphone output. My post above assumed that part of the project might be to add a headphone connector to the amp when it is being re-housed. I see now that wasn't what mountaingoat was saying.
Randy
Open baffle ?
returning to Mountaingoats original brief, I'm in a similar position i.e looking at simple to build single driver full range speakers to work with a T-amp.
I wonder if you had thought about Open Baffle ? They appeal to me for their simplicity and they clearly demonstrate a lot about speaker phase & wavelength, good for the students. They don't need as much complex carpentry and they could be very creative in finishing the large front area i.e paint designs on them
I think they also have that "how can that possibly work" factor which might intrigue them.
Elsewhere in this forum there are some gorgeous perspex & glass open baffle speakers, but at the other extreme you could build something with simple sheets of ply. I even recall seeing some cardboard openbaffle speakers in this forum.
just a thought
returning to Mountaingoats original brief, I'm in a similar position i.e looking at simple to build single driver full range speakers to work with a T-amp.
I wonder if you had thought about Open Baffle ? They appeal to me for their simplicity and they clearly demonstrate a lot about speaker phase & wavelength, good for the students. They don't need as much complex carpentry and they could be very creative in finishing the large front area i.e paint designs on them
I think they also have that "how can that possibly work" factor which might intrigue them.
Elsewhere in this forum there are some gorgeous perspex & glass open baffle speakers, but at the other extreme you could build something with simple sheets of ply. I even recall seeing some cardboard openbaffle speakers in this forum.
just a thought
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