DIY speaker box design queries

[MJ23Bulls]

Hello all!
I'm planning to build a TMW FS. This'll be my first ever build. I'm not at all a technician. But after reading so many diy projects, I'm just fascinated. That's the reason I'm here. With the pure passion for building one (and probably many more to follow) I'm here; I'm here to learn.
I've zeored in on Peerless drivers (W, M and T). I've a couple of queries, as of now. I appreciate your responses.

1. Speaker box design: An online calculator, Speaker box designer / Calculator is asking for the parameters of only one driver and giving the output for one driver enclosure only. Is there any software or any other methods to calculate/design the box? I'm confused here as there will be three drivers and which driver's measurements to input there.

2 Another doubt is about the total impedance of the system.

2.a) Scenario 1: W 8 ohms, M 8 ohms and T 8 ohms (In parallel)
Z = (Z1*Z2*Z3)/(Z1+Z2+Z3) makes it 21.33 ohm

2.b) Secenario 2: W 8 ohms, M 4 ohms & T 8 ohms makes it 12.8 ohms

Will it be prudent to use the 2nd choice to lessent the impedance so that the output will be more in terms of wattage.

2.c) Another scenario to lessen the impedance is to have two 4ohm Mids in parallel (WMMT). In this way, these mids will come down to 2 ohms. And now the Total Z will be 7.1 ohms

Please throw some light on these issues. Thanks!
Cheers!
BK

 

[hydrovac]

You have to design for three individual drivers. The crossover separates the signal into different bands, so the impedance seen by the amplifier is similar for each band.

So, if your woofer, mid & tweeter are all 8 ohms, a properly designed xover will provide an 8 ohm load to the amp.

However, 8 ohms is used as a nominal figure by manufacturers, for your xover to work properly you will have to measure the actual impedance of the drivers at the proposed crossover frequencies.
(or at the very least, get the figures from the manufacturers published graphs)

If you are designing your own did you measure the drivers yourself in the enclosure you plan to use? (or are you using other people's measurements?)

If you are building someone elses design - you should be able to get the overall system impedance plot from them to determine how nominal the load is.

I'm guessing you are designing your own. Do not even attempt to do this - especially for a 3 way if you cannot model or measure your design.

Without doing the above - you could very well design (by accident) a low impedance load and destroy your amplifier (let alone produce a speaker that could sound horrible).

Being able to model and measure is a must for new designs.

Cheers

 

[hydrovac]

MJ23Bulls,

Which peerless drivers have you selected?

 

[MJ23Bulls]

Thanks for your response and concerns, hydrovac.

....<<ed>>....

If you are designing your own did you measure the drivers yourself in the enclosure you plan to use? (or are you using other people's measurements?)

Nopes. I'm already confused with calculating the cab dimensions for 3 drivers as the online designer provides details for one driver calculation only. So, I haven't even warmed up for the race.

If you are building someone elses design - you should be able to get the overall system impedance plot from them to determine how nominal the load is.

Again, no! Not someone else's design. This doesn't mean I'm going to do it on my own. If the need arises, I'm more than willing to diy someoneelse's proven design

I'm guessing you are designing your own. Do not even attempt to do this - especially for a 3 way if you cannot model or measure your design.

You read my mind. Yes! I don't have any measuring equipments. If any FMs in and around Chennai who're willing to teach me or help in measuring these greeks ohyeah, I'll be more than happy. I'm not going ahead with this diy without measuring, that's for sure. Thanks!

Without doing the above - you could very well design (by accident) a low impedance load and destroy your amplifier (let alone produce a speaker that could sound horrible).

Got it!

Being able to model and measure is a must for new designs.

:clapping:
Got this one too!

I tried to multi quote; but couldn't succeed. So, for your next post on my selection of drivers, they'll be (proposed)

T: SR10DT 8 ohms 25mm fabric dome tweeter
M: M13NH 4 ohms 5" paper cone
W: S16NI 8 ohm 6" paper cone (I prefer a 6.5", with a rubber surround though!)

These specs are gathered from diyaudiocart & theaudiocrafts sites. PeerlessAudioIndia site isn't user friendly for me to navigate around and to look for what I want. They've listed 6.5" woofers. However, all with carbon cone.

As this is going to be my first build, I don't want to go overboard and at the same time, I don't want to diy a crap! I want it to be a learning curve.

With the drivers selection, I don't mind Dainty drivers (Budget permitting - My budget for the drivers ~ 3k; Crossover ~ 1.5 to 2k; Cab definitely with 3/4" MDF and if I can manage then can upgrade to 1"MDF).

Suggestions are welcome.

Cheers
BK