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JustANoob
(@justanoob)
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23/07/2020 11:49 am  

so just a while ago I assembled one of my Tower speakers and it has almost no bass, as in it can push a lot of bass, but it's really quiet compared to the rest of the frequency spectrum.

IMG 20200723 172508
IMG 20200723 172514

The pictures show the unfinished Tower and the assembled one. In theory, they should play down to 38 Hz. The used drivers are a Dayton Audio DC28F-8  1 1/8" Tweeter and two RS180-4 7" Woofers. The woofers are wired in series with each other and parallel to the tweeter giving a theoretical impedance of 4 Ohms. The 2 Ports are 43mm diameter and tuned to 39 Hz.

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This screenshot shows the theoretical frequency response using the official measurements given by Dayton Audio, which I would be very happy with.

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The pictures above show the crossover design for the woofers as well as the tweeter. They have been soldered together as shown on the screenshots, even with me checking them multiple times.

Is hope the data given help understand what's going on in my case. If you need anything else just ask and I'll try to provide it as long as I have it.

 

 

 

 


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123Toid
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23/07/2020 11:52 am  

At first look, I can see some things going on with your crossover that will need to be adjusted for. I have to do some work around the house right now, but I'll respond later today with some ideas of what might be going on. a few things right off the bat though, is that you shouldn't have resistors on the front end of your woofers like that. and it doesn't appear that you've really accounted for baffle step compensation. 


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JustANoob
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23/07/2020 11:58 am  

@123toid I think you may have mistaken the capacitor for a resistor as I don't have any on the crossovers but still thanks for the fast reply, I'll upload pictures of the crossovers in real life for better understanding.

IMG 20200723 175733
IMG 20200723 175737

 


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123Toid
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23/07/2020 12:01 pm  

@justanoob okay. It looks like 0.15 ohm resistor in front of the inductor. Maybe that's just showing your DCR. Is your cross over easy to get to? Or would it be easy to disconnect save the Tweeter if we wanted to run some tests later?


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JustANoob
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23/07/2020 12:34 pm  

@123toid Yes, it pretty easy to disconnect, also the resistors account for the resistance of the inductor. That's the way the program works, as it sees those as one unit.


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123Toid
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23/07/2020 1:01 pm  

@justanoob

Okay great. That resistance is referred to as DCR. That's neat it shows it like that. Just a quick clarification, you said you wired your woofers in series and Tweeter in parallel to get 4 ohms. That's not how that works. Your 4ohm woofers are now 8ohm 4+4=8, just like you started. However, in sister design, one you crossover, you crossover your impedance as well as response. So although you're correct two 8 ohm loads in parallel would be 4 ohm, that's not the case when you use a crossover. Theoretically,h tshould stay around 8 ohms.  Of course since impedance is not linear, that's not always the case. I haven't got a chance to input the data in to XSim yet. But just done good for thought, since I'm unable to get to my computer right now.


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JustANoob
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23/07/2020 1:56 pm  

@123toid Nice to know, I've checked my program about the impedance and as you said there is something going with the impedance. at around 80 Hz the impedance reaches 8 Ohms, the dramatically rises to 28 ohms at 37 Hz.

image

Now that we know that. what would be the best course of action.

From a quick few tries what to do it seems like the only thing that negated the spike was disconnecting the tweeter from its crossover, wiring the tweeter directly to the terminal, which in turn would endanger the tweeter, even though the response is still acceptable, I don't think it would be optimal.

impedance without xover

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123Toid
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23/07/2020 5:22 pm  

@justanoob

What size are the ports?  I am going to look that over as well.  

That peak at 37hz is the drivers resonate frequency, aka the FS of the driver.  It should be peaking around 38hz, according to Dayton's spec sheet.  So that is right on.

 


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123Toid
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23/07/2020 5:55 pm  

 

I looked over your crossover and there are a few things going on.  You are about 3db too hgh on your high end and don't have baffle step figured correctly.  It appears to be around a 9 inch wide box?  If that is the case, everything after 500hz should be around 3db down.That doesn't appear to be the case.  I also didn't notice any acoustic offset (z-offset accoutned for the woofers).  THis would probably be a combined 3.3 or so.  It's impossible to say for sure without having measure it.  But that is a guesstimate.  Here is a quick rundown of something that might work.  What I would do is at least test the woofer circuit.  You should have the components there to test get close enough to test that out.;  See if your bass returns.

try

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JustANoob
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24/07/2020 2:55 pm  

The ports are 43 mm diameter, the box is 230 mm wide which converts to almost exactly 9 inches.

I'll have to try your suggestion and I'll give an update on that when I tried. if there are any other questions regarding the box or anything feel free to ask


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123Toid
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24/07/2020 11:56 pm  

@justanoob

Try just the woofer section first and see if the bass is there.  Disconnect the tweeter.  If it is. Then proceed forward.  If not, let me knwo the internal box size and I'll take a look at the ports and see if there is soemthing going on there.


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JustANoob
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25/07/2020 9:39 am  

@123toid

Results are as following, they sound pretty comparable to the other towers I already have, both giving off a similar feeling presence when played at 60 Hz sinus with both of them cutting off at around 55 - 50 Hz and just playing the note but without any notable pressure.

Also played them with music multiple times having the tweeter disconnected switching between them on the amp directly without any tone control activated, then reconnected the tweeter and compared again the results stay the same with the most notable difference is the way they sound, as the other tower has a paper cone woofer, but that's not of concern here.

 


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123Toid
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26/07/2020 10:10 pm  

@justanoob

Is that with the new woofer crossover or the old one?  If it is the same with the new woofer circuit, then give the internal box dimensions and port sizes.  THat way I can see if anything is going on with that.  


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JustANoob
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27/07/2020 10:49 am  

@123toid That is with the new crossover, I currently had it playing a lot of different genres back to back and it sounds really good for my personal taste. I played a few EDM tracks, but also more vocal and instrument focused tracks like Fast Car - Tracy Chapman. 

I also redesigned the crossover a bit, considering that the highs are really nice but just a little sharp as they currently have the most peaks in the frequency spectrum. I'd like to have your opinion on the response.

image
image
image
image

This would be the crossovers for the drivers as well as the impedance and frequency response. Both are Linkwitz-Riley crossovers. The low pass is a 2nd order, while the highpass is a 4th order combined with a L-pad to bring down the tweeters response by -2 dB.


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123Toid
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28/07/2020 11:27 am  

@justanoob

That's great to hear! Glad you got it figured out 👍


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