# My DIY home tower project



## Medicineman

Based on the Sonus Stradavari and the Poor Man's Strad.
I will be using all ScanSpeak drivers: Tweet - D2904/7100, Mid - 12M/4631G, and Woofer - 18S/8531G.

I finally started building a test enclosure today. I should be able to finish it by tomorrow. I do not think i will have any measurements until next week.
I plan on building a passive crossover to start with. If I can ever find a preamp and DSP combination I like, I will go 3-way active.

Here is the design I came up with. I am trying for a tuning frequency of 25 Hz with an effective volume of 3 ft^3.





























Here are a couple of pictures to give you a better idea of what it will look like. The pieces here are not glued yet. I was doing a quick dry fit to check measuremets. The camera batteries died before I could get any better pictures.


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## kappa546

cool project.


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## chad

So are you doing all the geometry to angle all those cuts? Whew!

Those when finished right would look GREAT in my house! Keep posting pics!


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## Oliver

Hi Medicineman ,

Sweet !

Where will the ports vent out [bottom]?


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## s2groove

will the midrange have a separate chamber?


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## Medicineman

a$$hole said:


> Hi Medicineman ,
> 
> Sweet !
> 
> Where will the ports vent out [bottom]?



My design will have two ports venting through the bottom as in the Poor Man's Strad. The dimensions for the base will be decided after the enclosure is built. I want to make a base that will allow the angle of the speaker to be adjusted instead of having a fixed angle (Poor Man's Strad), but does not have toe stumping brackets (Sonus Stradavari).


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## 60ndown

im guessing the curved front kindof wave guides the sound into a wider and more transparent 'image'?

i wonder if 'bent' plywood would acheive similar results, screw making all those cuts n joins


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## Medicineman

s2groove said:


> will the midrange have a separate chamber?



Yes. The net volume will be about 0.5 L for the test enclosure. I will adjust as needed depending on what the frequency response looks like. I have used these drivers in both 0.7 L and 0.5 L pods in my truck. I thought the bottom end sounded better with 0.5 L. However, the HP filter was set lower in the truck than what I expect to use for this project.


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## Medicineman

60ndown said:


> im guessing the curved front kindof wave guides the sound into a wider and more transparent 'image'?
> 
> i wonder if 'bent' plywood would acheive similar results, screw making all those cuts n joins



LOL. It does take a little patience. Bent plywood would work fine. However, I have a specific goal in mind. If the design works as well as I hope, I want to build the final enclosure from solid walnut with baltic birch plywood for braces. I am designing this from a "speaker as furniture" kind of standpoint. I have already invested too much money in it to not have it stand out and look impressive.


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## 60ndown

Medicineman said:


> LOL. It does take a little patience. Bent plywood would work fine. However, I have a specific goal in mind. If the design works as well as I hope, I want to build the final enclosure from solid walnut with baltic birch plywood for braces. I am designing this from a "speaker as furniture" kind of standpoint. I have already invested too much money in it to not have it stand out and look impressive.


function>form

i bet you can sell the mdf version easy when your ready.


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## 60ndown

25hz seems very low? what kinda music you listen too mostly?


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## Medicineman

The wide/curved baffle helps eliminate the problem of baffle step. It should also give a smoother roll-off for the midrange for better mid/woofer integration (at least that is what I am hoping for).


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## Medicineman

60ndown said:


> 25hz seems very low? what kinda music you listen too mostly?


The first test enclosure will be based on ScanSpeak's recommendation of 42 L per woofer for a vented alignment. The tuning frequency of 25 Hz was chosen because it seemed to give a good roll off (soft knee) and pushed group delay lower down the spectrum.

Everything about this design is subject to change once I start testing and actually listening to it. I expect to build at least one more test enclosure before I am satisfied with it.


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## 60ndown

im guessing your familiar with the speaker page here?

http://www.decware.com/newsite/mainmenu.htm


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## thylantyr




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## spydertune

That is an ambitious project. I'd struggle just to make a standard box. Can't wait to see updates as you progress.


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## Medicineman

Nice looking arrays thylantyr. I might need a little more practice before I try a project like that. 

Well, yard work too longer than expected today. I did not have time to assemble anything, but I did at least get the parts cut.

Jigs for cutting internal braces.













Jig about to be put to use.













Finished braces. Ports will pass through the holes on the outer ends of the braces (at least for the bottom two braces). I will be using five braces total.













Biscuit joints are used to hold most of it together. If this project makes it to final production, I will use a "tongue and groove" type joint.












Eight inches deep!! Hard to believe it I got it right with all those cuts, lol.


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## chad

You sir have skillz, I'm pretty adventurous and willing to take on anything but calculating all those angles and getting them RIGHT wold drive me NUTS!


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## Medicineman

chad said:


> You sir have skillz, I'm pretty adventurous and willing to take on anything but calculating all those angles and getting them RIGHT wold drive me NUTS!


It really was not difficult for this project. I chose a 3" width for the boards based on aesthetics. I modeled several different variations for angles on the computer. I finally decided to make every angle (except for the end peices) five degree cuts. That gives me ten degrees at the joints once the pieces are fit together. It is much easier to keep the angle of cut the same for each board. So far it is working fine. Cutting all the slots for the biscuit joints was actually more aggravating than cutting the lumber, lol.

The hardest part is dialing in the table saw. I still have work to do on that. If the fence or miter gauge is off by even a fraction of one degree, it will make a lot bigger difference than what most people would guess.


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## 60ndown

even my square sub boxes require lots of teh cawk and 60 grit sandpaper.

no idea how you got that box looking so perfect?


**** id be off 1/4 just cutting the lengths of 3" :0


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## Luke352

I'm actually planning on building the Poor Man's Strad very soon, I was put of the design at first because I thought the build would be difficult but when I looked at the build process the designer used, it's incredibly simple if you use his method. 

Yours are looking great, I will be watching this thread closely!!!


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## spydertune

Medicineman said:


> It really was not difficult for this project. I chose a 3" width for the boards based on aesthetics. I modeled several different variations for angles on the computer. I finally decided to make every angle (except for the end peices) five degree cuts. That gives me ten degrees at the joints once the pieces are fit together. It is much easier to keep the angle of cut the same for each board. So far it is working fine. Cutting all the slots for the biscuit joints was actually more aggravating than cutting the lumber, lol.
> 
> The hardest part is dialing in the table saw. I still have work to do on that. If the fence or miter gauge is off by even a fraction of one degree, it will make a lot bigger difference than what most people would guess.


I appreciate you taking the time to post this along with your comments.

Metalworking I have no problems, woodworking makes me shake.


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## thylantyr

Medicineman said:


> Nice looking arrays thylantyr. I might need a little more practice before I try a project like that.


I didn't post that for you to build  

It's to show those certain concepts are similar


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## pahhhoul

wow! can't wait to see the final end results!


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## Matt R

Nice work man, looks good.


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## cheesehead

Very nice!

It sure is nice to see that the art of woodworking is not lost. 

Keep us updated!


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## Medicineman

Finished building today. I got careless mounting the braces. One of them is out of position and is messing up everything else. Oh well, it is only a test box, lol. I screwed everything down tight to make up for the mistake. I also painted the front. The uniform finish helps me find things that I might not like for a final design. Top and bottom pieces were cut from 1/2" MDF because I used all the 3/4" making jigs. I had planned on using 1.75" solid walnut for the final enclosure. After seeing the 1/2", I think 1"-1.25" thick might look a little better. 

I do not have an active set up in the house so I used my dc ref 650.6 for initial testing. Crossover point for mid/tweet was set at 3000 Hz LR2 (electrical). Crossover for mid/woofer was initially set at 350 Hz LR2. After a little listening, I decided the mid response was a little muddy. I changed the mid/woofer crossover to LR4 (electrical) and that seemed to solve most of the problem. Next, I lowered the output gain for the woofers by 3db (software setting for the amp). Things started sounding really good at this point. I alternated output gain from minus 3-5 db with a lot of different music. I could not really decide which was best overall. I think I may have a cabinet resonance issue. I know I have a fair amount of braces, but something sounds out of place with some music. It is the type sound I have eliminated from sub enclosures by doubling the wall thickness. Maybe the 1/2" top/bottom plates are causing the problem???

I had hoped to have FR measurements today. Unfortunately, something is wrong with my testing gear. I do not feel like dealing with it tonight. It will have to wait.

Braces:










Ports:











This should give you a better idea of the enclosure size.











Having some fun:











Hmmm, cabin gain really does make a difference!!  How about something else.


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## ViperVin

nice, very clean enclosures


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## Medicineman

Initial impressions:

Tweeter: Absolutely amazing!!!! It does everything right. Great dynamics and detail. No sibilance. Everything sounds REAL. 

Mid: Sensitivity (or is it transient response) too low to keep up with the tweet. Clean, slightly warm sound in general. I would like more "impact" from percussion. 

Woofer: Midbass response is excellent. Blends well with the mid. Low end response is more than I expected. Slightly boomy on the lowest notes (possibly due to cabinet resonance). I will need to play this inside the house to decide if enclosure volume/tuning freq will work.


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## cheesehead

Wow those are looking good!

All these threads about home speakers are getting me thinking about making some myself!


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## Medicineman

Luke352 said:


> I'm actually planning on building the Poor Man's Strad very soon, I was put of the design at first because I thought the build would be difficult but when I looked at the build process the designer used, it's incredibly simple if you use his method.
> 
> Yours are looking great, I will be watching this thread closely!!!


Let me know how it turns out. I may build that as well. I want to try it with 2 mids and 2 woofers per speaker (MTMWW) for a 93 db/watt/meter HT set up.


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## Medicineman

*IMPORTANT:* 1) My microphone is not calibrated. 2) I make no attempt to calibrate for an accurate SPL measurement.
*
Tweeter response* at 0, 15, and 30 degrees. Top end is a little ragged as Zaph points out on his site. I will make some adjustments to the baffle to hopefully flatten out the rising response. Off axis response surprised me. This looks more like the response for a 3/4" dome.












*Mid response* at 0 degrees. Near-field + far-field measurements merged at 200 Hz. The driver was 48" above the floor and distance to mic was 1 m. Far field measurements should be accurate down to 195 Hz with 5.1 msec gating.













*Mid response* at 0, 15, and 30 degrees. This is far-field only so don't bother looking at the response below 200 Hz.













I wish the mid could play a little lower. Crossover point might end up being higher than I want it. A 5 1/4" driver would work better.

I have not measured the woofers yet. I did listen to them full range for a little while. They do not sound boomy in the house. Hard to tell without having them properly crossed over. With test tones, the response seemed flat to around 80 Hz before slowly rolling off. I still had decent output at 40 Hz. I entertained myself for a few minutes by walking around the room to find modal points.


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## newtitan

WOOOOOOW that is friggin awesome

im so bad at woodwork, im still sanding my two SQUARE 0.5 cu ft jordan enclosures lol


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## Medicineman

*Woofer response* merged at 250 Hz. I forgot to clean up the crud below 25 Hz until it was too late to do anything about it. I am not sure how accurate it is below the merge point, but it seems to match well with what I am hearing. No need for a sub with this one.  I still plan on using my Dayton Ref 12HF with it, though.













This was my target response. I think my net volume is a little less than what it should be.












Does anyone have ideas/suggestions for me so far? My biggest concern is the tweeter response. I think I can flatten it out some by changing one of the angles on the baffle. It will be interesting to experiment with if nothing else.


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## Oliver

perhaps a filter.

at 0, 15, and 30 degrees. Top end is a little ragged as Zaph points out on his site. I will make some adjustments to the baffle to hopefully flatten out the rising response.


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## Tode9

Medicineman said:


> Does anyone have ideas/suggestions for me so far? My biggest concern is the tweeter response. I think I can flatten it out some by changing one of the angles on the baffle. It will be interesting to experiment with if nothing else.


I certainly cannot offer suggestions, complete neophyte presently, but posing a question based on a few baffles and measurements I made this weekend. Do you really feel that changing the angles with affect the change you're looking for?

It would seem to me that the frequencies which are cause for concern are more effected by the primary baffle plane, the 9" wide one, to which it's mounted. Maybe if you were to attenuated the tweeter output and shift the slope you'd have better luck than changing the baffle angles.

I asking just as much to potentially help as to potentially learn.


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## 60ndown

newtitan said:


> WOOOOOOW that is friggin awesome
> 
> im so bad at woodwork, im still sanding my two SQUARE 0.5 cu ft jordan enclosures lol


lol,

get an electric sander and some 60 grit.


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## bmaupin

> Does anyone have ideas/suggestions for me so far? My biggest concern is the tweeter response. I think I can flatten it out some by changing one of the angles on the baffle. It will be interesting to experiment with if nothing else.


Like Tode9 suggested, I do not think that you are not going to get any major changes to the tweeter response from changing the baffle shape or adding felt, but felt should be easy to try. From looking at your relative SPLs you should have enough tweeter SPL to be able to hit your target SPL no matter how much (little) BSC you incorporate. I say this since the SPL for the 12m in your graphs is 80db when it should be about 90db. A rising tweeter response is easy to tame with either a zobel or BSC type shaping circuit (inductor & resistor in parallel, and that in series with the tweeter). The optimization in SoundEasy is great and you should be able to try different shaping circuits easily.

I would avoid merging near field and far field for your project. Generally when you merge nearfield and farfield you apply the diffraction to the nearfield and then merge the two together. Since you cannot directly model your box shape in SoundEasy, I'd think that you will need to measure with a sufficiently long window so that your measurements are valid to about an octave below your woof/mid cross point.

I am no measurement expert, but I have read lots about what others have tried/suggested and have done a couple designs with SE and they have turned out very good.

Where are you trying to cross? I wonder where a good point to cross the 12m is to get good impact. I see that Troels crosses it at 700Hz in the Ekta. I have been sitting on a pair that I have been planning to create a three way with and use the Dayton RSS265HF as the woofer, but I'd like to cross the RSS no higher than 350Hz - maybe I should use the 1st gen HDS 5.5" PP mids that I have. 

Great looking project so far. It should be well worth the effort.

- Brad


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## Medicineman

Tode9 said:


> I certainly cannot offer suggestions, complete neophyte presently, but posing a question based on a few baffles and measurements I made this weekend. Do you really feel that changing the angles with affect the change you're looking for?
> 
> It would seem to me that the frequencies which are cause for concern are more effected by the primary baffle plane, the 9" wide one, to which it's mounted. Maybe if you were to attenuated the tweeter output and shift the slope you'd have better luck than changing the baffle angles.
> 
> I asking just as much to potentially help as to potentially learn.




The idea is to change the angle between the 9" center section and the first 3" section to each side. The angle will be changed from 10 degrees to 5 degrees. Basically, the whole center section will be flatter. I have no way to model the change in FR. It may work, it may not. Only one way to find out. *IF* it works, it should give me more flexibility with the crossover point and potentially minimize the number of cross over components needed to reach a target response.

I can build a curved baffle cheaply and quickly. There is no reason not to experiment at this point. Plus, it is fun.


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## Medicineman

bmaupin said:


> Like Tode9 suggested, I do not think that you are not going to get any major changes to the tweeter response from changing the baffle shape or adding felt, but felt should be easy to try. From looking at your relative SPLs you should have enough tweeter SPL to be able to hit your target SPL no matter how much (little) BSC you incorporate. I say this since the SPL for the 12m in your graphs is 80db when it should be about 90db. A rising tweeter response is easy to tame with either a zobel or BSC type shaping circuit (inductor & resistor in parallel, and that in series with the tweeter). The optimization in SoundEasy is great and you should be able to try different shaping circuits easily.
> 
> I would avoid merging near field and far field for your project. Generally when you merge nearfield and farfield you apply the diffraction to the nearfield and then merge the two together. Since you cannot directly model your box shape in SoundEasy, I'd think that you will need to measure with a sufficiently long window so that your measurements are valid to about an octave below your woof/mid cross point.
> 
> I am no measurement expert, but I have read lots about what others have tried/suggested and have done a couple designs with SE and they have turned out very good.
> 
> Where are you trying to cross? I wonder where a good point to cross the 12m is to get good impact. I see that Troels crosses it at 700Hz in the Ekta. I have been sitting on a pair that I have been planning to create a three way with and use the Dayton RSS265HF as the woofer, but I'd like to cross the RSS no higher than 350Hz - maybe I should use the 1st gen HDS 5.5" PP mids that I have.
> 
> Great looking project so far. It should be well worth the effort.
> 
> - Brad



SPL levels shown in the graphs are NOT accurate. I have made no effort to normalize output either for a single driver or between different drivers. At this point, my only concern is overall FR for each driver in relation to different cabinet designs. 

You are correct about the merge point. Thanks for pointing that out. Looks like I will need to measure in the shop after all. The shop has a 12' ceiling and a lot more floor space. I should be able to get accurate measurements down to around 100 Hz if the higher noise floor does not cause problems.

I was hoping to cross the mid around 350 Hz. After seeing the FR, I might have to reconsider. A third order filter might work at that frequency (fourth order LP on the woofer), but then I would have to deal with phase/lobing issues (which I am still learning about). 600 Hz looks like a good place for LR2 between mid and woofer. I may have to play with that in the days ahead.

Great comments so far bmaupin. Keep them coming! I need all the help I can get. Especially when I start designing the crossover. I still have a lot to learn in that area. The crossover section in Sound Easy was not that difficult to learn. Figuring out what data to plug into it is going to be the hard part.


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## Medicineman

Thanks again bmaupin. I had completely forgotten about Ekta. It seems a higher mid/woofer crossover point may work well after all.

Here are some links for anyone interested:

Ekta:
http://www.troelsgravesen.dk/Ekta.htm

Ekta Grande:
http://www.troelsgravesen.dk/ektagrande.htm

Discussion of optimal crossover points:
http://www.troelsgravesen.dk/Design_criteria.htm


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## Tode9

Medicineman said:


> The idea is to change the angle between the 9" center section and the first 3" section to each side. The angle will be changed from 10 degrees to 5 degrees. Basically, the whole center section will be flatter. I have no way to model the change in FR. It may work, it may not. Only one way to find out. *IF* it works, it should give me more flexibility with the crossover point and potentially minimize the number of cross over components needed to reach a target response.
> 
> I can build a curved baffle cheaply and quickly. There is no reason not to experiment at this point. Plus, it is fun.


By all means experiment. While you're at it, no reason not to sand down the edges at each angle change, giving you a smooth curve, no?


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## Medicineman

Tode9 said:


> By all means experiment. While you're at it, no reason not to sand down the edges at each angle change, giving you a smooth curve, no?




That will be experiments number 4 and 5.


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## Medicineman

I spent some more time listening to the test enclosure last night. A mid/tweet crossover point at 3k LR2 still seems to work best. EQ'ing out the rising response of the tweet seemed to improve coherency with the mid. I like the combination much better now.

The mid/woofer crossover point was moved to 600 Hz. I think this will work very well, but the woofers will need to be moved higher up the baffle. The higher crossover point made the resonance problem I mentioned before worse. It took me a few minutes to realize it is port resonance and not box resonance as I had first thought. I used 3" pvc for the first enclosure because that was all I had in the shop. WinISD predicts the first port resonance will occur at 370 Hz (with the enclosure tuned to 25 Hz @84 L). The next enclosure will use one 3" port venting out the rear. Tuning needs to be adjusted so that the first resonance is at least one octave above the crossover point.

Does anyone have experience bending hardwood? Any links? I am getting closer to a final design but I can't figure out how to pull it off LOL.


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## bmaupin

Any updates? Just remembered your project and was wondering what's up.


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## FocusInCali

Looks like you're building something similar to this $61,000 ATC EL150 SLP at
http://www.atc.gb.net/el150slp.htm


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