build my own crossover

[thomash85715]

Hi: Got some nice monolith 3s but missing their external crossover. No wonder they were cheap! I would like to buy a big inductor and the correct NP cap but what are the values? I know this is a low rent solution but it is only temporary till I can afford to buy the little boxes assuming that is possible. Thank you for helping light these big boys up tonight! --Tom

 

[MotorToad]

http://www.the12volt.com/caraudio/crosscalc.asp calculators to get your values.

Crossover design is pretty simple in basic theory, but a teensy bit complicated in application. Something I've always wanted to do is build a speaker system and play with variable capacitors

and coils

just to hear what happens.

Neat, just found this on wiki http://en.wikipedia.org/wiki/Audio_crossover

Keep in mind that any filter will have an effect on phasing. Googling showed many sites such as http://www.play-hookey.com/ac_theory/band_pass_filters.html that can give you a peek at the surface. This isn't exactly what you'll be doing as a crossover is more of a separate LPF for the woofer and a HPF for the panel that are just set at a level trying to acheive a full-pass system. There's no reason you can't do as well or better than what's out there on the market.... or maybe produce the worst-sounding speakers ever... jk.

 

[IWalker]

http://www.amazon.com/Loudspeaker-D...8790319?ie=UTF8&s=books&qid=1178916385&sr=1-1

is a book I have that I haven't read yet...but am going to hopefully sit down and read through this weekend. A good starting point for crossover design from all I've been told. There's a new 7th edition out, but you can get an older one for cheaper. The link above is to the newer one.

You can get a cheaper active crossover (which doesn't introduce the same phase issues, I believe) for around $230. (Behringer DCX 2496) Takes some technical knowhow to set it up...but you won't have to upgrade to the stock active crossover...this one should do just fine for the long term.

I'm guessing the monolith's active crossover requires you to have seperate amps for the panels and woofers, right? (I think this is a prerequisite of active crossovers) Just be aware that going the active solution will have that extra cost. Building a passive crossover will likely be more expensive than you think...and requires you do find out a lot about what you want before you start...and you can't adjust your results very easily, without starting over...or at least redesigning the circuit (for moderate to large changes) If you've already got the second amp ready, the active solution will be much less of a headache. IMO. JonFo is very technically savvy and has monoliths, so I'd value his judgement above mine on this subject.

 

[thomash85715]

thank you

That link was perfect. But do I use calculators for 8 ohm or 4? If the overall final impedance the amp sees is 4, then would the two paths be assumed to be roughly 8 ohms each? I can't tell from that 12volt site how to ascertain that. If I look at the DC resistance of the two driver units on the speaker, will they be around 6 ohms each or more like 3 and what would that mean in AC impedance terms? I have not done that yet. Again, much appreciated. :bowdown: --Tom

 

[IWalker]

These are some of the questions that make an active solution very attractive.

 

[JonFo]

Hi: Got some nice monolith 3s but missing their external crossover. No wonder they were cheap! I would like to buy a big inductor and the correct NP cap but what are the values? I know this is a low rent solution but it is only temporary till I can afford to buy the little boxes assuming that is possible. Thank you for helping light these big boys up tonight! --Tom

Thomas, I have a deal for you.

I have two unused Monolith IIIp passive crossovers sitting in my HT.

Let's make a deal...

PM me.

 

[IWalker]

Thomas, I have a deal for you.

I have two unused Monolith IIIp passive crossovers sitting in my HT.

Let's make a deal...

PM me.

Woah...talk about helpful!

 

[Dominick22]

Pick suitcase #22! LOL

Dominick

 

[thomash85715]

just confirming here

I sent you a private message JonFo about these crossovers of yours. THey will help me a lot. Thank you. --Tom

 

[JonFo]

I sent you a private message JonFo about these crossovers of yours. THey will help me a lot. Thank you. --Tom

No problem Tom. I figured one day, someone would need these.

PM and emails sent.

Here’s what they look like (sitting at the foot of one of the Monoliths).
They are not small, and weigh close to 10 lbs apiece.