Hello Folks! Looking forward for an enriching experience

[aerialsinthesky]

Hello people,

I am Srini, from India. Right form my chilhood I have always had an ear for good sounding speakers and although calling myself an audiophile would be a far fetched thought, I really value good sound reproduction a lot!

Off late, this interest for DIY audio has grown on me. With the itch to get my hands dirty becoming unbearable, I started a bookshelf speakers project last week, even when I am a total noob when it comes to DIY audio.

Here’s what am upto:

1. I have some salvage teak wood pieces lying with me for a couple of years and I plan to use them for the baffle
2. When I sold my old car, the buyer told me he wouldn’t pay me anything for the audio setup I had put in (about 40 grand INR). So I thought, why not remove the speakers and throw in a basic pair? I salvaged a Rockford Fosgate 5 1/4″ component speakers and 1″ tweeters. The components come with a build in cross-over. So the build should be simple. Or so I think 🙂

Although I have started off, I am not sure whether these are gonna give me a good output. 

 

Here are some questions that I need help with right now:

1. The teak wood pieces are 1″ thick. Are they too thick for a baffle?
2. Like in pic 2 above, I am gonna stick the pieces to get a striped finsh and then sand them before I polish. I remember seeing this kind of baffle on youtube some time ago but can’t find the link to it. Just want to know that this design doesn’t compromise on performance.
3. The other sides of the enclosures are either gonna be made of 3/4″ply-wood or teak panels. Which one would be better?
4. how do I decide whether I have to do a ported or a sealed enclosure?
5. How do I calculate the enclosure size required? Is there a minimum and a maximum to it, given a speakers frequency response? I have a 7.5″ x 9″ x 9″ on my mind.

 

Thanks in advance,

Srini

[imcokeman]

Hi Srini,

Welcome to the forum! It looks like you have a cool project starting and I’m not the speaker builder expert, but I know there are a lot of details needed to really make things “right” so for others that might be able to get some more info from it here is a page from what I think are those speakers.  If you can validate the model numbers though that would be good.

https://rockfordfosgate.com/products/details/p152-s/

Good luck either way.  Out of curiosity what do you plan on using as your amplifier?  You’ll want to make sure it can handle the 4ohm car speaker setup vs standard 8ohm home speakers.

 

[123toid]

@aerialsinthesky

Sounds like a pretty cool project.  I am excited to see how it turns out.  Since these were originally designed for a car, they are typically best used in a sealed arrangement.  Luckily for you, sealed can be quite forgiving, so the size of your box, will probably be just fine.

As far as the rest of the material.  I am not real familiar with teak, but it is a hard wood.  So there shouldn’t be any major difference in sound quality between a good plywood versus teak.  Just have adequate bracing and you should be set.  Soft wood, is where there can be more of an issue. 

I am assuming you are using the crossover that rockford gave you?

[tvor-ceasar]

Welcome Srini! Nice set of drivers you have there, and the Teak will make a stunning enclosure.

I did a bit of digging and found this PDF that has the minimum pieces of information needed to help you design an enclosure, namely Fs (Free Air Resonance), Qts (Q total system), and Vas, (equivalent volume). If you scroll down to page 3, you’ll see they are , 70 Hz, 0.68, and 0.19 ft3 (or 5.4L), respectively.

For ease of discussion, I’ll stick with your outside dimensions above and figure that the face will be 1″ Teak and the rest of the box will be 3/4″ plywood / MDF. That’ll give you an inside box volume of  0.183 ft3, before mounting any drivers. Let’s work with that.

Also, looking at the Qts of 0.68, that puts it in the sealed box range, but we’ll mess around with different types, just for fun.

Sealed box of 0.183 ft3 will yield a Qbox of 0.95 and will be tuned to about 97 Hz.

If you try a ported box of the same size, you could use a 1-1/4″ ID tube port that is 2-2/3″ long and it would tune down to 71Hz. That would come with a 5dB boost at resonance, which you may or may not like. And with the small Xmax, it shouldn’t stress that size port.

Last thing to contemplate would be to mount the woofer to the front of the face plate (baffle) and the tweeter to the rear (inside) with a nice wide bevel on the opening in order to help time-align the drivers. I don’t know the dimensions of them, but I bet that the 1″ difference would almost line them up.

 

Now, if you would be willing to go with a bigger box, that would change things, but we can visit that later on, if you wish.

 

Again, welcome to the forum and this great hobby we all love. Looking forward to hearing more from you.

 

[aerialsinthesky]

Posted by: @imcokeman

Hi Srini,

Welcome to the forum! It looks like you have a cool project starting and I’m not the speaker builder expert, but I know there are a lot of details needed to really make things “right” so for others that might be able to get some more info from it here is a page from what I think are those speakers.  If you can validate the model numbers though that would be good.

<a title=” removed link ” href=” removed link ” target=”true”> removed link

Good luck either way.  Out of curiosity what do you plan on using as your amplifier?  You’ll want to make sure it can handle the 4ohm car speaker setup vs standard 8ohm home speakers.

 

Hi imcokeman,

Thanks for the spec sheet.

I have ordered a nobsound 2 Channel 4-Ohm 50W per channel amp from Aliexpress. Waiting for it to be delivered. It has got Bluetooth 5.0 and a TPA3116 which would be sufficient for my requirements.

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[aerialsinthesky]

@123toid,

Thank you. Teak is hard wood and is pretty dense. It’s the best-suited wood for furniture making that you can get for around $70 per cubic feet. The woofers have cross-overs build into them, so I am not going to need a new cros over for now.

 

For the enclosure, I am going ahead with a sealed type leaving some space for the port just in case I have to add them later on.

Here are some calulations I have done on the Web.

 @TVOR-Ceasar,

Thanks a bunch for the specs, it really helps. I had another rpdf with me and it didn’t have mounting details. For now, it’s gonna be a sealed box. I am going to mount both the woofer and the tweeter from inside of the box. Like in Screenshot 2020-02-21 at 2.46.58 PM.png I somehow like the way it looks. Do you see any downsides to mounting the woofer fromt he inside?

Thanks,

Srini

 

[123toid]

@aerialsinthesky

Just a heads up, those calculators leave out a lot of information that is necessary to make a good ported decision. I know you’re going sealed now, but I would recommend downloading a program like WinISD. This will allow you to pay attention to port velocity and excursion of the woofer, which this calculation doesn’t take into effect. I’m really looking forward to seeing this when it’s finished. Please tag me when you finish it, so I make sure not to overlook it. 

 

[aerialsinthesky]

@123toid,

Thanks for headsup. Will check out WinISD too.

Last weekend, I could complete only the sides of the box and cut the front baffle. Unlike the US, advanced level power tools (like a router table, table saw, mitre saw, jointer, planer) are very rare to find here. Working with hand power tools makes the process slower because I have got to measure each thing very carefully to get a good fit and finish.

Some pics:

 Any ideas for polishing the wood, anyone? I am thinking of laquer coating but I want a matte-finish.

[123toid]

@aerialsinthesky

It looks beautiful.  I have always appreciated the work done with hand tools.  It really gives it that custom made finish look, which is hard, if not impossible to replicate with power tools. 

 

[tvor-ceasar]

You can laquer it and then use a very fine sandpaper to break the gloss down to a matte finish, if you don’t have access to something that dries to matte.

Here’s a page that breaks down the various grits and their uses.

[123toid]

@tvor-ceasar

 

That is a great resource!  

 

[aerialsinthesky]

Okay. Here’s the first look of the speakers.

They’re almost done, except for:

• The round-over for the tweeter baffles
• Polishing/Varnishing the enclosure
• Some air getting out of the rear baffle (will fix it this weekend)

How do they sound?

I am testing it with an unbranded, below-average amp and it sounds awesome! Haven’t tried playing flac or 24-bit yet as the amp supports only mp3 from a flash drive. 

I am plannig to pair it with this 2.0 bluetooth Amp eventually. Has anyone tried this amp?

Initially I had bought speaker binding posts that come in an FRP plate and connected them on the rear baffle and the output was so-so. I then connected the wires directly and I could see a sea of difference. The mids and highs are crystal clear and punchy. The lows are there but not quite tight. Anyways, this project wasnt intended for in-your-face kind of bass. So all in all, I am happy that my first project came out really well, although I didn’t have a lot to do as the woofers came with built-in crossovers.

Here are a couple of questions I have:

• Will stuffing the inside of the enclosure with poly-cotton/micro-fibre from a pillow, or any other damping material increase the quality of output? What role does it play?
• Should I stick damping material to the inner walls of the enclosure?
• I have put crimps to connect the wire to the speaker inside the enclosure? Will soldering improve anything?
• Individual binding posts over binding post plates? Which one is better? Can someone point me to a good example on parts express (not too pricey though)?

 

I would like to thank everyone in this thread who’s helped me with advice and reference materials.

Stay safe, people 🙂

[123toid]

@aerialsinthesky

First fo all great job on your first speakers.  I can’t wait to see the final project once you get it sanded and sealed.  As far as answering your questions.

1. You can stuff it and it serves two major roles.  The first, it can reduce standing waves inside the box to clear up the sound.  The second, it can increase the Q of your box which will increase the low end extension.  Just add a little at a time, until you feel it sounds best.  You do not want to overstuff it.
2. Since this is sealed, you can just lightly stuff it in there.  If it was ported, you would want to line the walls.
3. Crimp connectors are just fine. Soldering will not have any audible difference
4. There is very little to no difference.  The main thing is if you want a custom plate.  I use these all the time and love them: Terminal Cup

Here is a video I did on the low end extension of poly fill:

 

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