Crossovers

[4 Strings]

Can anyone help me with this? I'm thinking about a high pass filter for the top cab of my set up (a 2x10) so it doesn't have to try and handle low frequencies which can go to the bottom (the Hartke Pro1800 'Monster' described in another post).

Are these off the peg? Can I dial in the frequency? Should I bother anyway?

How will this affect the overall impedance? (top speaker is 8 Ohm, bottom is 4 Ohm, amp would prefer to see 4 Ohms total)

Thanks

Edited November 4, 2010 by 4 Strings

[Bill Fitzmaurice]

[quote name='4 Strings' post='1012226' date='Nov 4 2010, 12:04 PM']Should I bother anyway?[/quote]
No. There isn't enough difference in the response of the two cabs to justify it. All bass cabs are full range, quite different from better PA cabs that are designed to operate within distinct bandwidths.

[4 Strings]

[quote name='Bill Fitzmaurice' post='1012256' date='Nov 4 2010, 04:20 PM']No. There isn't enough difference in the response of the two cabs to justify it. All bass cabs are full range, quite different from better PA cabs that are designed to operate within distinct bandwidths.[/quote]


Fair enough, I was trying to make life easier for the top cab as it would no longer be required to reproduce low frequencies.

Even with bi-amps there's no crossover so the same goes to both (sets of) speakers.

[Stewart]

[quote name='4 Strings' post='1012329' date='Nov 4 2010, 05:29 PM']...
Even with bi-amps there's no crossover so the same goes to both (sets of) speakers.[/quote]

The term bi-amp (to me) implies a crossover at signal/line level with two power amps feeding individual high/low frequency speakers

There isn't a term I'm aware of for multiple differing drivers being fed by one or more amps without any form of crossover, but I'd like to suggest JBOS (Just a Bunch Of Speakers)

[essexbasscat]

If you're curious, why not play ?

Just get hold of a Peavey MK III or MkIV head, with crossover control on the front panel. Just plug your cabs in and play

What's more, you can control the crossover frequency !

Have fun !

T

[stevie]

[quote name='Bill Fitzmaurice' post='1012256' date='Nov 4 2010, 04:20 PM']No. There isn't enough difference in the response of the two cabs to justify it.[/quote]
Yes. Because you're likely to blow your amplifier up if you don't. You could try a 47uF bipolar cap in series with the top cab, which should maintain the system impedance at 4 ohms. Pm me your info and I'll send you one. No guarantees, as you really need measuring equipment to do this properly.

Edited November 4, 2010 by stevie

[LawrenceH]

Bi-amping with a crossover will allow you to send more bass to the Monster without worrying about the 10"s (plus it's theoretically a bit louder for the amount of watts under certain circumstances). Whether it's worth it or not will depend on the 10"s - I'd imagine if you're driving them hard you'll get a cleaner, tighter mid-range while still getting a big fat bass from the Monster.
It's probably not worth using a passive crossover. I suppose you could try a simple high-pass cap to protect the 10"s if you want to send ridiculous amounts of low-end to the monster.

EDIT: Just noticed Stevie's post and realised I hadn't spotted you were driving the amp below 4ohm! In which case, what he said. Crossover or bi-amp.

Edited November 4, 2010 by LawrenceH

[4 Strings]

[quote name='LawrenceH' post='1012497' date='Nov 4 2010, 07:55 PM']Bi-amping with a crossover will allow you to send more bass to the Monster without worrying about the 10"s (plus it's theoretically a bit louder for the amount of watts under certain circumstances). Whether it's worth it or not will depend on the 10"s - I'd imagine if you're driving them hard you'll get a cleaner, tighter mid-range while still getting a big fat bass from the Monster.
It's probably not worth using a passive crossover. I suppose you could try a simple high-pass cap to protect the 10"s if you want to send ridiculous amounts of low-end to the monster.

EDIT: Just noticed Stevie's post and realised I hadn't spotted you were driving the amp below 4ohm! In which case, what he said. Crossover or bi-amp.[/quote]


Yep, realise its running at an average 3 Ohm but, to be honest, the Monster will be out on occasional use (more's the shame).

[rmshaw37]

I've found that with a 210 plus 115 set up, you need to feed them with different signals, otherwise they clash, gives a certain sound but certainly not the sum of it's parts! I crossover and there is a difference, especially with volume!

[4 Strings]

Interesting, what cross over do you use, or is it inbuilt to you amp?

[Mr. Foxen]

There is a difference between a crossover and low/high pass filtering. A crossover splits off, a filter only allows whichever to pass, if you want to save your cab some work, you only need a high pass filter (a capacitor at simplest).

Using two amps without crossover and same signal (as in not stereo) is dual amping, or at least I've considered that to be correct.

[Phil Starr]

[quote name='stevie' post='1012492' date='Nov 4 2010, 07:51 PM']Yes. Because you're likely to blow your amplifier up if you don't. You could try a 47uF bipolar cap in series with the top cab, which should maintain the system impedance at 4 ohms. Pm me your info and I'll send you one. No guarantees, as you really need measuring equipment to do this properly.[/quote]

Good advice. This will filter out the signal at about 400Hz at 6dB/octave and a reversible electrolytic will only cost £1ish (go for 100V rating) so you can afford to try it at little cost. You could use lower ratings for experimenting with if you don't crank up the power.

I'd give it a go and try fiddling. Buy a handful of capacitors and try adding them in parallel until you get the sound you like best. Doubling the number will double the capacitance and halve the cut off frequency. If you've some speaker leads with bare ends you can wire this all up with 'chocolate box' connector strip whilst you are fiddling. If you have access to an electronic crossover of course you can do this more easily.

Of course BFM may be right and this won't give you a better sound but without trying we are all guessing. Cutting the bass to the tops this way will increase their power handling within the system and will raise the overall impedance, dependant upon what frequency you end up with. Cutting the bass will cut the bass (duh) and make the mids stand out more. This may be good or not, there is only one way to find out.

reversible electrolytics are getting harder to find, Maplin used to stock a wide range, also search for non-polarised electrolytics.

Edited November 12, 2010 by Phil Starr

[Bill Fitzmaurice]

[quote name='Phil Starr' post='1021019' date='Nov 12 2010, 04:20 AM']Good advice. This will filter out the signal at about 400Hz[/quote]Filtering a 2x10 that's designed to work to 60 Hz or lower at 400Hz is going to cost a lot of midbass output. That's OK if you don't need that output, but then you're schlepping around a lot of cab for no good reason. Fully 3/4 of the cab's size is there to allow it to go that low.

[chris_b]

This is getting complicated!

For an even bigger sound I'd suggest the Mesa Boogie 215, with 2 EV 15's, in the For Sale section. You won't get a bigger or better sound than that!!