Design Iteration. Did I choose the wrong drivers? Help Please!

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Just curious, why are you set on doing a 3 way? It's totally fine if that's just what you want to do, but if the reason for it is so that you can achieve some other design goal, then it may be that you can achieve that more effectively in another way.

It might be helpful too if you tell us a little bit more about what you're trying to achieve with these speakers too. So far I see small and floorstander and 3 way as your goals.

Do you have other goals as well? Things like max SPL or F3 frequency? Intended use (i.e. home theater, music, etc)? If we know those we might be able to help point you in the right direction more effectively!

I'm looking forward to seeing how the project goes for you!


Hi,
Thank you for taking interest. I would love to share the details. Please be patient as you go through them below.

1. Target Room Size. So I drew up the design of the living room where I intend to keep the speakers along with measurements. Please see attached image to get a good idea of that. Height of media console is 1'3" if its relevant.

2. 3 Way. Its a design goal because I want to deal with the complication of that. So I have a background in computer engineering, and I dealt with circuits, actually made of lot of them including band pass filters in 200 300 level classes. I deviated to computer hardware, but I know how most electrical components work. (The theory of filters not so much). So I'm looking forward to diving in and reliving that. I understand, building something in an engineering lab vs building a final product is very different, but whats the point of knowledge If i cant apply it.

3. Intended Use : Although I plan to keep the tower speakers on both sides of my television. I dont quite want to call it a home theater setup, since I hardly watch movies, but do play quite a few games so it would be nice to have the speakers for that. But mostly I would use it for music. Also I would want the speakers to be powerful enough for an average-large sized room, since I rent and would be moving around, so I might be in living in a plcae with a bigger living room.

4. My Expectation from Speakers: I like a lot of rock and alternative music. Big low bass doesnt excite me much. I Like crisp sound. Now here is an assumption I want you guys to clear out. Does a 3 way deliver better performance in mids and highs since there are dedicated drivers to handle specific ranges. (But if I can have a little extra bass, without compromising audio quality, doesnt hurt to have it)

5. Size, I initially wanted a smallish-medium sized tower, but when I actually ended up doing the measurements of the planned speaker cabinet (as per calculated volume), It turned out to be smaller than I wanted. So now, I want to do a 2*6.5" + 5" / 4"mid + 3/4-1" tweeter (I;ve done the cabinet measurements for it, Im OK with that size). Here are two subwoofers and a mid I like. I've yet to do simulations, but I'll keep you guys posted. In the meanwhile please give me some feedback on these drivers.
(Sub: Dayton Audio DC160-4 6-1/2" Classic Woofer Speaker )
(sub2: Dayton Audio DCS165-4 6-1/2" Classic Subwoofer 4 Ohm )
(mid: https://www.parts-express.com/pedocs/specs/294-1141-faitalpro-5fe120-8-specifications.pdf )

6. Perfection comes with Practice. Now this is my first speaker build and I know some of you will point out I should start with a simpler build but I really want to do a 3 way because there is some design and debugging challenge to it. I'm not looking to end up with a very well built 3 way (Ofcourse I'll try, but from an engineering standpoint things rarely go that smoothly,), but thats the whole point. I dont want a speaker setup ASAP. Its more of a hobby project, so I dont mind failing multiple times before I get what I want. So please support me going for this 3 way build, haha.

7. I have 20 days off and approximately a 500-600$ dedicated budget. So hopefully money is not going to be a progress hindering factor. My driver expenses are at about 350.

8. Amp Specs: 100 + 100 W at 8ohm, 165W (probably total) at 4 ohm. (This one: R-S202 - Overview - Yamaha - United States )

9. Loudness: I dont know how to say how loud, but I want it be pretty loud at times when I'm feeling the itch, but not party loud (IMO those speakers always lose clarity in the higher ranges).
 

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Here are my random thoughts.
Goals are important. Knowing what you are shooting for and what your compromises are is a key to success.

Questions like:
How large is your room.
How much power does your amp have?
Is your amp stable into low Z loads.
How loud do you need to play?
What speaker dimensions are you willing to live with?

A 2 way with a 7' driver in a .75 Cu Ft box can have stunning base.
I helped build a Modula MT and it was great.
My brother built a 4" full range in a 1/4 CU Ft box and added a 3/4" tweeter with an L pad and a Cap.
It wasn't as efficient or as loud, but it was nice in a small room.

Good luck with your project.
Please see my last post.
If there are any missing details that could help you to help me, please let me know :D

Thanks again the feedback.
 
Boneyxy,

Considering the very low impedance you are faced with why not just stick a 2.2 ohm 10 watt resistor (wire wound) in series with the input to the crossover network. This will no doubt introduce a power loss but your amplifier will easily cope with that loss and the added resistance will possibly improve the bass response somewhat by raising the Qts of the bass driver. Damping factor is largely negated in passive crossovers anyway and with such a low speaker impedance it is hardly a benefit at all. Experimentation in loudspeaker design is what makes it so intrguing and additive, most of us here have been caught in its web.

C.M
 
3 Way- Final Design- Comments/Suggestions? -SPL, IMP, Phase, Circuit Attached

Hi Everyone,

I'm trying to build a 3 way. I posted about it a few days back with a failed design due to wrongly chosen drivers(If anyone is curious. Thread: https://www.diyaudio.com/forums/mul...eration-choose-wrong-drivers-help-please.html ).

I changed my drivers, looked at some other designs and I think I'm gonna go ahead with this new one. Does anyone see any potential pitfalls?

One of my concerns is the Impedance dip to 3.5 ohm. My amp is rated for 100+100 @ 8 Ohm and 165 @ 4 ohm. There is a resistor for the same reason in series to the crossover circuit. (I intend to use one with high-wattage rating).

Another thing, I understand what baffle diffraction is. But I don't quite understand how to account for it in the whole loudspeaker design (I understand how enclosure dimensions affect this and placement of the speaker, woofer and tweeter). But I would really appreciate if someone can explain it a little better.

Also, here are links to spec sheets of the drivers I intend to use:

Woofer 7" 8ohm: Dayton Audio RS180S-8 7" Reference Shielded Woofer 8 Ohm
MidRange 5" 8ohm : FaitalPRO 5FE120 5" Professional Midbass Midrange Woofer 8 Ohm
Tweeter 1" 4ohm: Peerless by Tymphany XT25TG30-04 1" Dual Ring Radiator Tweeter

I intend to make a vented box for the woofers. But should I do another vented for the midrange? Would a sealed suffice?

Any feedback / suggestions are very much appreciated.

Thanks
 

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Hi,
In your des_2 data files, did you use the drivers frequency response from the manufacturer's data sheet and use Virtuix to copy and paste them into the programme?
At the same time did you run the diffraction model within the programme with your chosen cabinet dimensions inputted to get your final data?

It looks like it will play loud.
Good luck with the build.
 
Do NOT use a vented box for the mid. Sealed is better because venting produces a phase/time delay which doesn't matter that much for a woofer but you don't want it in a midrange.

For a few Dollars more you can get the XT25TBG60 which is a better tweeter. Note the double magnet is not for shielding but to increase sensitivity and reduce distortion.

I'd cross to the Faital (which I like a lot) somewhere between 200 to 300Hz.

All my speakers eventually find themselves on a back wall and because of this I never bother with baffle step compensation. Not a fan of it in free standing speakers either since it puts too much bass into the room, especially if you play your stereo louder. Tone controls on the amp are very much preferable.
 
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One of my concerns is the Impedance dip to 3.5 ohm. My amp is rated for 100+100 @ 8 Ohm and 165 @ 4 ohm. There is a resistor for the same reason in series to the crossover circuit. (I intend to use one with high-wattage rating).

All reasonably designed hi-fi amplifiers these days should handle the current from a 3.5 ohm load if the phase is reasonable. Exceptions are things like cheap AVRs which are aggressively built down to a price but even these often have a switch for a 4 ohm load which limits the current to what the circuitry can handle.

A speaker design that uses resistors on the woofer is not just bad but arguably broken. Given this is a new lightly constrained design it is wholly unnecessary. If your amplifier can only handle an 8 ohm load then design an 8 ohm speaker.

Another thing, I understand what baffle diffraction is. But I don't quite understand how to account for it in the whole loudspeaker design (I understand how enclosure dimensions affect this and placement of the speaker, woofer and tweeter). But I would really appreciate if someone can explain it a little better.

To get a feel for the effects of baffle dimensions on the drivers you are considering you can play with something like this or equivalent if it is not already included in the speaker design software you are using.

A design that is close to what you are considering in terms of configuration and budget is Zaph's ZDT3.5. Note how an inductor is used to introduce the baffle step correction for the narrow baffle and pair of midwoofers crossing high to a 2" midrange. This approach wouldn't work crossing low to a 5" midrange but there are other approaches. This is an example of why you need to sort out the speaker design before choosing appropriate drivers.

Note that a 5" midrange is larger than ideal for crossing to a 1" tweeter and is close in size to the woofers. So one would expect there to be something about the speaker design that benefited from an overly large midrange to compensate for the drop in quality of the midrange/tweeter region. What is it? This is of course another example of why you need to sort out the speaker design before choosing appropriate drivers.

I intend to make a vented box for the woofers. But should I do another vented for the midrange? Would a sealed suffice?

Sealed is usually fine and what is normally used because, unlike a woofer, the midrange is normally high pass filtered above the frequencies relevant to box loading and the output from the rear of the cone absorbed by the stuffing.
 
+1 on Sealed midrange. A sealed enclosure limits excursion below Fs, among its other advantages.

Your Amp is 4 ohm capable. All 4 Ohm rated speakers typically drop below 4 ohms at some frequency. Since Most amps are current limited, it may not deliver the full 160 watts at 3 ohms, but it will not fall to pieces. I drive 4 ohm nominal speakers with a 6 ohm class D amp. No issues whatsoever.
Do not use a resistor to fudge it. Just a waste of power. And the alignment change in the woofer would not necessarily be desirable.

Looks like you are on a better path.
 
Yes indeed, looks like a better path. Glad to see you move away from the subwoofers and towards a higher quality woofer. If you can afford it though, I would still look at the Anarchy - it will dig deeper than the RS180 in about the same size box. Needs a little longer port though I think.

You might also look at 1 of the Faital 4" drivers. Better suited to crossing up around 3KHz which is exactly where the XT25 needs to be crossed, although the off-axis response of the 5" looks like it will be fine up at that frequency as well. You could lower the woofer/mid xo point though. There is no particular reason for it to be up around 600Hz.

In your xo, see if you can simplify the circuits and get the desired target curves without the zobels - there isn't really any need for them unless you can't get the the curves you want without them. Try adding an extra resistor to the shunt circuits if you need a little extra help shaping the roll-off. Also, wire up the 2 woofers in parallel and then simply put 1 xo filter in front of them instead of the same filter twice before each driver.

Of course, without including the proper baffle diffraction and baffle step loss in the sim, your xo values will be incorrect. If indeed you put them right up against a wall and need little or no baffle step compensation, then a high sensitivity mid is warranted, but if you need the full 6dB of compensation, then you'll have to pad down the mid a fair amount. Also be careful in your sim that you are matching all the drivers at the same power levels - some are listed at 1W/1m and others at 2.83V/1m which are not necessarily the same thing.
 
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