Transmissionline Ipod Docking Station

[h@kan]

I have a pair of Peerless P830986 fullrange drivers that I have never found a proper home for and when the need for a portable Ipod Docking Station came up I decided to try them out. The speakers will be driven by a tripath TA2024 amp board with some mods from the sureelectronics Tripath boards thread in class-d section.

Since I will place it on a desktop the size was limited to width 450mm, hight 200mm and depth 300mm. I found that any bigger than that would look a bit strange on a desktop.
With my new updated mathcad woorksheets from Martin J king (thanks for making the service avaiable again) I came up with a 62 inch 2:1 transmissionline with the driver position 8 inch from the closed end. Working with google sketchUp simoustanely gave me a quite funny construction that I really wanted to try out. The size, 450x180x275[mm], was actually smaller than my predetermined limits.

Mathcad MJK simulation

Sketch

Then I built the box out of 10mm MDF, the sides was sliced halfway to allow them to bend.
The baffle is just for testing purpose, I will build a new one from some fancy wood later.
I have not yet decided the finish but I think it will be white except from wodden baffle.

After a day of listening to it (passive driven by a gainclone) I decided to go all way with it and mount the amp inside it and try to find a proper ipod dock for it.

The bass response is really impressive remembering that there is just 3" drivers playing.
I noticed some lack of the higher frequencies and I think I will add some small tweeters crossed over with just a capacitor from 10000hz or so.
Did some diy measurements.
I will probably stuff the line a bit harder trying to get rid of some of the ripple at 100-200 hz.

Thats where I am right now.

Does anyone know where to find a panel mounted ipod dock?

Regards H@kan

 

[GDJ]

I like what I see so far. Nice work!

As for the iPod dock, I have no idea.

 

[chris661]

You can buy them as a unit that will sit on a desk, and plug into a hifi system. Ask about them at your local shop.

Example: http://www.richersounds.com/product/ipod-mp3-accessories/cambridge-audio/id10/camb-id10-ipod-dock

You could probably take the cover off and mount it yourself.

Chris

 

[h@kan]

I found another one on ebay . Handy with a remote I guess.

I added some stuffing in the first two sections and I think this will be the final stuffing.

 

[h@kan]

Some more work done.
No ipod dock yet though...

Added some cheapo ribbon tweeters ($5 on ebay) crossed over with only a capacitor. They actually sound really good! I use them to help 10000hz and over and for that they are perfect.

I wonder how low you can push a 3 inch driver?
This driver has a Fs of around 80hz and this system delivers 45hz at resonable spl.

Regards Håkan

 

[johnnyfive82]

thats a badass speaker like the design

 

[planet10]

H@jen,

That tweeter looks a lot like these ApexJr Ribbon Tweeter.

Living in the baltic, you must have easy access to baltic birch?

dave

 

[ianpengelly]

That is awesome, what a great idea! I suspect it is considerably better than most iPod docks you can buy and in a better finish. Well done.

 

[h@kan]

H@jen,

That tweeter looks a lot like these ApexJr Ribbon Tweeter.

Living in the baltic, you must have easy access to baltic birch?

dave

It looks like that tweeter for sure! They are quite nice considering that they cost almost nothing. I have tried to cross them at 4khz 12dB but that was not a good idea, I think that they should be used >8-10khz

I live in Sweden (Scandinavia) and that not far from the Baltic states so the need to get the famous "Baltic birch" instead of our own Swedish birch have never crossed my mind. I don't know for a fact but the quality should be almost the same.

Regards H@kan

 

[planet10]

It looks like that tweeter for sure! They are quite nice considering that they cost almost nothing. I have tried to cross them at 4khz 12dB but that was not a good idea, I think that they should be used >8-10khz

Next time you need a budget tweeter you should also have a look at these from Steve:

Speaker Stuff

I've been buying them 30-50 at a time, really useful for adding some zip on the top of a widebander. Ask Steve for the diyA special price.

I live in Sweden (Scandinavia) and that not far from the Baltic states so the need to get the famous "Baltic birch" instead of our own Swedish birch have never crossed my mind. I don't know for a fact but the quality should be almost the same.

We call stuff from Sweden or Finland BB too... should be considerably better than MDF. (i burned enuff MDF on the WE to make 50 of your cute little TLs, more to go)

dave

 

[doorman]

Clouds of toxic smoke over Finlayson Arm!!
Don

 

[planet10]

The synthetic carpet was the worst.

dave

 

[rhapsodee]

Back to the topic : The speakers are awesome!!

Could you share how did you do the white finish for the MDF on the back? Was the front baffle from a wooden kitchen chopping board?

 

[h@kan]

Back to the topic : The speakers are awesome!!
Could you share how did you do the white finish for the MDF on the back? Was the front baffle from a wooden kitchen chopping board?

Thanks!

I applied spray filler in thin layers and sanding between each layer. I used one can (300ml) of spray filler. After that I used white spray paint for car rims. One can was more than enough. The result is not perfect but good enough considering the time consumed.

The baffle is made of an oak kitchen worktop.

Nowadays it lives in my SAAB 96 🙂

Regards Håkan

 

[Dr_EM]

Really nice job! Seems like it's producing outstanding bass considering the size of the drivers 😎

 

[renfrow]

Those look seriously spiffilicious! Do you have a dimensioned drawing for them?

 

[enigmaticEntity.]

I hope you have that secured; wouldn't want it hitting your passenger in the back of the head!

Nice design, I would like to build a TL one day, but I'm not sure whether just using MJK's TL alignment excel spreadsheet is enough... 🙂

 

[h@kan]

Those look seriously spiffilicious! Do you have a dimensioned drawing for them?

Images attached. The dimensions for the lower chamber (line) are the same when the speaker is flipped....that sounded a bit weird but I think you know what I mean 🙂

I hope you have that secured; wouldn't want it hitting your passenger in the back of the head!

Nice design, I would like to build a TL one day, but I'm not sure whether just using MJK's TL alignment excel spreadsheet is enough... 🙂

Anyone who has had the honor to ride in my SAAB 96 has asked me the exactly same thing, "I hope that you have secured that thing you have on the rear window shelf?" Yes its secured with two screws through the rear deck.

Thanks for your concern 🙂

Regards H@kan

 

[Buckapound]

Nice design. I've been looking for something to do with a pair of Tang Band WS-1750 S 3" square "woofers" I have laying around.

However, I'm a much better box builder than a math guy. Anyone care to comment on the suitability and/or need to make changes to the general dimensions of the transmission line shown here for the different driver? Here's some of the parameters, comparing the two:

Peerless 3" FR T-B WS-1750 S 3

Nom. Imp. 8 ohms 8 ohms
DC Resistance 6.5 ohms 6.5 ohms
FS 83.8 hz 65 hz
QMS 5.04 5.5
QES 0.67 0.34
QTS 0.32 0.59
VAS (ltrs) 1.8 1.8
Sensitivity 84.2 dB 84 dB

Not sure what else is needed. I'm planning on knocking one out of two layers of foam-core (paper-styrofoam sandwich board) just to see what it sounds like. Any suggestions are welcome.

--Buckapound

 

[Alex from Oz]

I wonder how low you can push a 3 inch driver?
This driver has a Fs of around 80hz and this system delivers 45hz at resonable spl.

If you use EnABL you'll go lower than you would have thought possible.
I'm currently playing around with these: TDK Electronics - Tremor S60 Multimedia Speakers

The subwoofer uses a single 3 inch driver in a bass reflex.
The bass performance after EnABLing is amazing given the limitations of the system.

Cheers,

Alex