My DIY Speaker Project

[GeniX]

This is it, boys.. this is *the* thread! I will endeavour to keep a running log of my project here.

First step - choosing drivers. Here are the cheap options I have sourced:

4" driver, -6db at 68hz (if i read the specs correctly)
http://www.audax.com/products/details/HP100G0.shtml

tweeter
http://translate.google.com/translate?hl=en&sl=fr&u=http://www.audax.fr/standard/tm020j11.html&prev=/search%3Fq%3DTM020J11%26hl%3Den%26lr%3D%26ie%3DUTF-8%26oe%3DUTF-8

The tweeter is rated higher in terms of power rating than the driver - should this matter? More importantly the tweeter is more efficient for sound reproduction.. is this normal, and will I need to dampen it in the crossover (beware of your answer - you could end up helping me with the crossover later on).

Its already working out more expensive than I thought for a 'cheapest speaker' that I can build. But Ill see where it takes me...

[Robh3606]

It is normal for a tweeter to have higher sensitivity. You just have to pad it down. From the spec sheets it looks like you will need a 3 db pad which you can easily do as part of your crossover.


http://members.tripod.com/XSSpl/Audio/Lpad.htm

Rob2:)

[gonefishin]

Cool idea about having a running log thread Genix...looks like ya got a couple good DIY'ers here to give you advice from time to time...as for me...I'll be reading the experience you gain from your project and the advice you get.


:beerchug:

[bully]

x, are you space-challenged? There is nothing like a 15-inch driver for pushing air!

pete
Neat project!

[GeniX]

Bully: No, not space challenged :) Price challenged. Also I didnt want a HUGE woofer... and as my calcs should show later in this post, a 4" should provide enough range.

GF: Thanks for the support! Yeah Ive been searching the net like crazy - lots and lots of information out there (although good information is a tad rarer - lucky the guys here know a whole deal )

Robh: Cool - sounds like a plan. Ill leave that worry for when I get to the crossover (Im trying to get a handle on the basics of electronics.. its really a brain-breaker). Impedance, resistance, reactance? Until recently I thought 8ohm was 8ohm !

---

OK. Ive tried a bunch of alternative sources - including a few guys locally who work in the audio industry here. Their collective statements sum to 'try *so'n'so*' and 'there is a good company over in australia who...'. So I am content that I have exhausted enough search space inside New Zealand to warrant paying the shipping from Australia despite it costing more for the drivers & tweeters than I wanted to spend on this project IN TOTAL!

I spent most of the last couple days trying to use various online calculators and working out conversions from litres, cubic feet, and various other forms of measurement. Just yesterday I discovered by reading the help that the program I downloaded (WinISD) can actually do all of that itself! I swear some of the stuff doesnt look clickable - but it is!

Thus I have calculated the following based on the HP100G0:

Minimum volume needed: 2.5litre
Ideal box: 13.6cm x 22cm x 8.2cm

From there I toyed with various options and did a whole lot of reading on various sites. I have decided that my plan of attack will be a vented box design. Simply because the port gives more flexibility in tuning, and vented box gives a bit better efficiency.

My chosen box will at the moment be around 9 litres volume. The port will be tuned to 70Hz, 6x2cm rectangular and 5.09cm in length.

Box size without yet taking into account the space taken up by the port will be around:
W: 18cm
H: 35.82cm
D: 23.00cm

This should include the allowance for the 18mm thickness of the MDF.

By calculation from the program, just above 60Hz somewhere is the -3db point. I reckon in reality my cabinet dimensions wont be precise, material may give added vibrations, and probably less than ideal port positioning will make the programs calculations into rough estimates. Still thats bringing the response down low enough to give the project enough frequency bandwidth to give music enough to be listenable.

Projections by the software show quite some variation in phase. I dont think Ill concern myself too much with it as I have no clue how to compensate for it (probably in the crossover, right? - lets keep that as simple as is reasonable).

[GeniX]

Okay.. drivers & tweeters should be on order from australia soonish - put thru the order today.

Meanwhile Im trying to make up a list of goodies to get hold of either purchased, borrowed, stolen, or whatever-- just a quick brainstorm. Please add items you may think I am missing:

* 2 x Drivers (on order)
* 2 x Tweeters (on order)
* 2 x sets of 24 screws (4 per side panel, 8 for front, 8 for back)
* Wood Glue
* Some sort of sealant
* binding posts for back (where do I get these???)
* crossover parts (have to wait until ive sorted out the design)
* some length of wire to use internally for wiring.. 14 guage?
* solder
* soldering iron (yeah.. i dont have one of these)
* screws for driver and tweeter (have to wait for the parts)
* veneer type thing for 'finish'
* speaker cloth (for grille)
* smooth material I can apply over the MDF Ill be using to construct the port
* sealant or foam to go between driver and wood its screwed onto (or is this a bad idea?)

* Volt meter (will I need one during crossover development, or can I just take a simple design, make it and have it work?)

Please suggest other items Ill likely be needing, or give comments on type/brand/use of the above items. Remembering too that Im still trying to keep these cheap - I shouldnt really even be doing this right now as my credit card stands.

[GeniX]

woohoo! Got the drivers and stuff today! Just in time for the weekend. All *seems* in good order at this stage.

Hopefully I can get a start tomorrow (Sat)

[GeniX]

Well it has been a slower than expected weekend. I was unable to get in touch with the friend from whom I was going to borrow the power tools on Saturday. I did, however by most of the stuff Ill be needing - with the exception of the crossover parts.

A short trip to DSE revealed that I cannot get hold of inductors from them, and they had a limited range of caps. I did find a 16v 10uF electrolytic cap, but didnt buy it. I might have to have the crossover stuff ordered from JayCar in auckland.

I managed another trip today (Sun) to get the remaining bits and pieces - MDF, screws for drivers (doh! forgot to get these on sat), masking tape... and I borrowed the power tools from the friend who gave me transport to get the MDF.

--

In short Ill do the measuring and marking on the MDF tonight, sort out the crossover parts tomorrow - and work will commence this week. Furthermore I will be taking photos of this lot as it progresses.

Just FYI, I should have all the parts Ill be needing (excluding the XO), and my money spent thus far is NZ$300.

This includes:
* speaker wire (for internals), solder, screws for cabinet, screws for drivers/tweeters
* MDF, drivers, tweeters
* wood glue, silicone sealant, binding posts
* soldering iron & stand (yah yah I dont have one of these)

aah.. come to think of it, I still need padding for the inside. But I reckon that should come real cheap.

Thus far I reckon its final finish may just be spray-paint. A possible good option suggested by my friend was oil-based paints that might help smooth over the MDF a little.

Who knows - Ill leave that for when things are almost done.

[GeniX]

Ive just finished measuring and drawing wee little pencil lines across the MDF. Its taken me an HOUR AND A HALF to do all the lines Ill need for the main cabinet ( doesnt include cutout circles for driver and tweeter ).

Why you may wonder? Well, being new to this, I imagine precise and calculated accuracy is a MUST. So I double checked my dimensions for all sides. Measured everything that was possible to do so from an edge of the wood, and not from another measurement (thus trying to allieviate any compounded error). Furthermore all lines were rechecked at varous crossing points to make sure all the distances were exact. If they were a mm out (which one was) I went backward finding the measurement that was inaccuracte, redid it and then rechecked the intersecting lines for correct distances. I have left spaces between all cuts so the width of the saw doesnt throw things out.

After all that, mixed with a few cups of tea (trying to stay off the excessive coffee), it seems done. I just hope the lengths I have measured so precisely are correct! Ill recheck them tomorrow or before I cut.

I did go the long way about it tho', and will certainly pre-plan in future projects my measurements on paper so as to minimise the actual measuring and orienting the ruler.

So far as I can see, ive accounted for *everything*, and these boxes better damn-well be a perfect fit.

[Robh3606]

You cut wood yet?????

Regards Rob2:)

[GeniX]

lol! I tried! After work on wednesday - got out the benches, circular saw and whatnot. Never having used one, or done this before I was in for a surprise.

Even with the ear-muffs on, I could still hear it quite loud.. and soon realised that at 8pm, this is *not* what the neighbours wanna hear. Add to that the fact that I have no garage, and so it was in the back yard with the neighbours just over the wall.

All I did was saw one piece in half. Im planning to cut the wood this weekend - probably with the help of a friend (will be great having an extra pair of hands to hold wood and such). In addition to this learning experience, I will be obtaining somehow a C-Clamp or pair thereof to hold some straight object (probably another piece of wood) onto the MDF as an edge along which I can run the circular saw, thus obtaining a much more straight cut than I think I am capable of with my hands alone.

My design has changed a bit in my head, and I may extend it somewhat. I was thinking of the front baffle being angled at 45 degrees along the edges (which I can then sand a little to smooth it over). Ofcourse fixing the front baffle onto the adjoining sides will be difficult, but I plan to have another piece of MDF (18mil) on the back of the front baffle.

Think of it more as a box with holes for drivers, and then an additional piece of MDF (aka: the current front baffle with sides angled at 45 degrees) on top. Little bit more work, but sexier look? Also be a bit firmer with less vibrations.

Although someone I know recommended against doing 45 degree cuts on MDF because it doesnt really have a grain... comments?

[Robh3606]

If I understand you correctly you want to do 45 degree bevel cuts and then round so you can round the front baffle edges of the enclosure???

I would not bevel and then sand you arms will fall off before you are done!!!! Does you friend have a router????

In case you don't know what one is it is a tool designed to bevel ,round, or cut paterns such as what you see with diferent styles of moulding.

They are easy to use once you do some cuts on a scrap piece.

Take a look at my unfinished cabinet. All the edges were done with a router after the boxes were together. You can buy almost any patern cutting tool to give the edges of the cabinet any shape you want.

http://www.audiokarma.org/forums/showthread.php?s=&threadid=1509

The only issue would be sealing the MDF. Check the MDF thread there were some great sugestions there on sealing and finish. I ended up using shelac to seal mine and it worked well.

Always wear ear protection it just amazes me how load a saw can be!!!!! I cut in the afternoons my neighbors wouldn't like it either.

Regards Rob2:)

[GeniX]

Im not sure what you're saying! Ill try clarify what Im saying in the meanwhile --

same way ill cut the front baffle from the MDF, only picture the cuts being made with the circular saw set to 45 degrees. This means the back of the baffle will be the right size for the cabinet, but the front face of it will be smaller and a 45 degree slope around the edges.

When I put this on the main cabinet, Ill attach another piece of wood on the back to help fit & screw it to the cabinet.

[Robh3606]

Oh Ok I missed that! LOL

So you have double thick front baffle with the top piece beveled??The second piece is to help hold it together??

Hey I am on the other side of the world and you are 12hrs ahead of me!

If that ain't right :confused:


With mine I built the boxes and then used a 3/8 radius bit on the router to round the edges. Could have used a bevel bit too. The whole thing was glued and screwed before I rounded the corners. What I did does not remove enough material to matter strength wise. Also the router is very easy to use. Easier than with a circular saw. A table saw is easy to bevel with too. Just set your jig and go.

Well have fun hope I got it right this time:D

Regards Rob2

[GeniX]

Went to the local hardware store today, and asked for C-clamps.. salesman didnt seem to know what they were, so he took me to F-clamps. I bought a set of 3 which were cheap, but upon seperating them at home and having a look, theres no way to 'lock' the moveable bar.

Yes I inspected and tried everything (not that there is much to an F-clamp). So I went back (another 30 minute walk for me) to the store, returned the goods and had a look through the hardware section.

I found the products whose names are (clearly printed on their labels) 'C-Clamps', and they were indeed what I was looking for. However I noted that the hardware store's labels (not that on the packaging) called them 'G-clamps'. So I bought a couple, and came home.

Didnt get all my sawing done, but I cut most of the cuts. I need to trim off a lot of them as at least one side has some area which I have marked to be cut-off as 'wasted space'.

Pictures are still proving tough to try and arrange for you lot -- I dont have a digital cam, not even a normal camera. I may borrow my flatmates camera, develop the film and scan 'em in.

I need tips for the last trimming. I have a jig-saw, but having used one for 10 minutes - in my life - Ill need tips for how to get a straight-ish cut. I assume that once its down to a few mils, I can just sand off the rest? Is that how its done?

[Thatch_Ear]

Getting a straight cut with a jig saw is much more difficult than with a circular saw, but you have the problem of clamping and getting the motor to clear the clamps.
If you have enough scraps or can get some more cheaply it is not hard to make a cheap version of a table saw by attaching your circular upside down to a piece with a slot cut in it for the blade, bolt holes resessed for the bolt heads. Basically a very srtong box the saw will be bolted into with only blade sticking up.
Then you can more easily see your marks and get a closer cut.
I know you have been told to use ear protection but you need eye protection and always a dust mask. Especially with MDF. The dust can be poisonous. Ply wood probably uses some nasty stuff for glues and some woods are themselves poisonous to breathe the dust of. Carefull of your fingers, power tools are very powerful and if something grabs a piece of clothing or you, you can easily come up missing pieces.

[GeniX]

thanks for the tips - I used some protective glasses with the ear muffs. I did not have any breathing protection, and despite working outside where it was windy as anything (and overcast and rainy on and off too), I still probably got a face-full of dust.

I think some has found its way into my left eye.

Hopefully I will finish the cuts and such this week, and just need to glue&screw on the coming weekend.

Ill probably want to consider doing the finish on the cabinet before I put the drivers & tweeters in.

[GeniX]

I did more cutting today after work (went in to the office an hour earlier so I could leave an hour earlier). I got a bit done, and managed to also make a stupid blunder :o

I had decided to finish off all cuts that I needed the circular saw for (which were just a whole lot of smaller off-cuts). While sawing, and thinking that after such meticulous measurement, a bit of forethought would have cut down the number of cuts I need to make by a small margin, I did something quite foolish.

Having measured how far from the marked line the circular saw must be held, I have been quite successful cutting most cuts leaving a very small margin over the line that Ill have to sand or something later. Now in a fit of stupidity I realise that the cut I am about to attempt is awkward, and decided to just turn the bench I am using around and cut from the other side.

The result was that instead of cutting a few mils over the line, I cut a few mils before my marked line. Just my luck, the opposing side did not have excess and so I had just made one panel a bit too thin. So I figured 'oh hell - may aswell just do whatever for the rest' and I cut the rest of my cuts not worrying too much about which side of the marked line the cut would fall on.

I will remeasure the pieces I have, and the cabinet size will probably end up reduced by half a cm or so in each dimension. The remeasurements should not see any line being brought in more than 5mm, and so I reckon Ive done all my circular sawing - Ill just have to sand a bit more than I originally thought I would.

No train-smash... yet...

[Thatch_Ear]

Mr Murphy watches over us all. I haven't found a way to avoid him yet.

[Robh3606]

Well I have not managed to build a speaker yet that I didn't cut on the wrong side of the line or measure something wrong. You have lots of company:D

Rob2:)

[GeniX]

Right. Its 3:20pm Saturday right now.

Thinking I was about done, I was all keen to source an electric sander of sorts. A friend of my flatmates reckoned if the excess on the edges was enough that I need an electric sander, I have cut rather badly.

So I got out the jig-saw, and went over each piece, cutting as close to my pencilled line as possible. Some cases it was more like 'shearing' off thin 1 or 2mm layers on the edges.

The result is that I found I can cut much closer and more accurately with the jig-saw than I can with the circular. The circular does, however, cut very straight. I think, perhaps, that there might be some sort of alignment or 'calibration' things which need to be tightened on the circular, which was why my cuts werent as good as they could have been.


I measured and cut the holes for the drivers & tweeters. What a mission! A jig-saw is not made for ciruclar cuts. In the case of the tweeters the hole is small enough that I have to saw slowly, turning pretty much at the maximum rate the saw will allow. I burnt the wood a little in a couple of places. Just went darkish/blackish colour. I take it that this is not serious.

Good thing is that both for the driver holes, and the other wood cuts, my cutting is now pretty much on my pencil line. I should be able to sand it by hand now.

I have decided against doing my fancy 45 degree cuts on the front baffles since I cant get the circular saw to lower its blade after tilting 45 degrees (I pushed and pulled the lever I think is the one quite a bit). Deciding that I would rather not break the damn saw (since it isnt mine), I will stick with just a plain box.

This afternoon (well in half an hour or so) I want to get around to cutting the holes in the back for the ports and binding posts. Tomorrow Ill do the sanding I think.

One thing that has struck me is the sheer amount of tools and *things* needed for making cabinets. Essentially one wants Circular Saw, Jigsaw, Router (I know what these do.. kinda, but have never used one), something for cutting holes (I hear parsexpress has a special jigsaw for cutting driver holes), electric sander, electric drill. And thats just the powertools list...

yeah.

[GeniX]

Oh yes, the cabinet size has been reduced due to my mistake a few days ago. It is now (externally) 18cm x 35cm x 19cm (coming down 1cm for the height AFAIK).

You guys should start recommending to me what kind of stuffing (what do you call it?) I need to put in the cabinet. Why is it needed? Just some foam around the inner walls?

[Robh3606]

You need to use fiberglass on the inside of the cabinet. I use fiberglass ceiling tiles. You just strip off the outer covering and cut them to size. They are 3/4" thick and do a good job. You can add layers if more is required.

Regards Rob:)

[GeniX]

hmm... whats the 'stuffing' or lining for? Theres an old pair of Pioneer speakers in the house (bookshelfs) and they dont seem to have anything lining them inside (not that I have opened them up - just trying to peek and push fingers thru the port).

They also seem to be made out of something like MDF, but not as thick as I am using nor as dense.. does there exist an 'LDF'?

[Thatch_Ear]

You can also buy a really cheap Dacron stuffed pillow and cut it open. Not as good as the more expensive fills but pretty close. 1 pillow goes a long way too.
Another very good thing to do is using a spray adhesive to cover the inside walls with the smallest bubble- bubble wrap with the flat side glued to the cabinet. This goes far in reducing standing waves and will make the tuning process with the dacron easier.

[GeniX]

Well, I popped round to the hardware store and got some sand paper.. 80, 120 and 220 if I recall the 'grit' (right word?)

By clamping a piece of wood on the sand paper, and then rubbing the edge I want to sand along the sand paper, propped up by the wood, I have been able to get rid of the 'hump' that comes from sanding the other way around where I hold the sand paper, and the wood is stationary. The sand is also semi-flat - good results for such a rudimentary solution. Ofcourse a plane would have been better or so I am informed.

Ive sanded over half the pieces of wood Ive cut. A few more tomorrow, and Ill finally be able to start putting the cabinets together.

I also spent some time at a store specializing in paints, and by recommendation of the salesman, just got a can of high-gloss black spray paint. He reckoned for smallish speakers, theres probably no need for a primer (although it would be better if I did apply one), so he said just do an extra coat of paint and the first should absorb into the wood partly and act as a primer.

All up, a semi-productive day considering I only started doing things after 1pm (prior to that was waking up from going to bed at 2am).

I cant help but think that if I had cut right the first time, I could have chopped my cutting time in half, and may not have even had to sand some edges had I cut right in the first place.

Oh well, you live, you learn. Sometimes... :D

[GeniX]

What a waste of time today has been!

I went into town to get some F-clamps so I can start glueing and screwing my cabinet finally. The local hardware store (Mitre10) are as helpful as ever (ie: impolite, and generally no help).

So I didnt get F-clamps - they had none. Could you believe it. So I get back home and try to screw the mdf without the use of clamps - that was the dumbest idea I ever did have.

Not being able to screw fast because its a little wobbly, one side of the MDF actually starts to seperate - its ripping apart the layers it seems to be made from. The screw on the other end gets thru with much less fuss, but doesnt make headway into the MDF sheet its joining on to. Thus I have one *front baffle* (no less) that has one corner starting to seperate, and one hole where an attempted screw used to be.

Oh I got so angry. Lack of workspace at my place, no real workbench to do work on with lack of woodwork tools really puts a dampner on things... especially when one makes a fine mess of whats probably the most looked at piece of wood on the cabinet.

Ive called it a day - I will erupt into a shower of gibs I tell you if anything else breaks on these damn speakers.

Despite my want for doing DIY, this project is trying really hard to hammer into me that if one doesnt have the space, tools, and knowhow to do something, any attempt will lead to many times the time taken with poor results and much frustration.

argh!

[Robh3606]

I can be very frustrating when things go wrong. Did you drill pilot holes for the screws?? MDF will split as you say. What you can do to minimize it is to drill a hole smaller than the screw so it still has good bite in the material. Once the glue sets you can actually take the screws out so don't worry about getting them super tight. You just have to have them resonably tight to hold the thing together as the glues hardens. Have a couple of beers and give it another go.

Regards Rob:)

[GeniX]

*phew* its been so long since I have posted to this thread!

My cabinets are glued & screwed. I havent yet put paint on. Ive been taking pictures with a throwaway cam, but will wait until film is full to develop.

I have my crossover designed (now a 2nd-order linkwitz-riley around ..er.. 3khz if i recall). Parts are found, but I havent had time to order anything.

Work has been hectic - major milestone coming up, and last week saw three nights where I got home after midnight. It may be similar time schedules for the coming weeks.

I was hoping to have the project done a bit of time ago, but looks like its going on a little :-/

--

This project *will* be finished tho'.