BillFitzmaurice.info

Is there anyway to put a passive HPF/LPF in between the mixer and amplifier?

Really what I want to do is make a couple of XLR-XLR adapters with some passive electronics inside which will give me a 40hz HPF when I put it in series with an amp feed.

I have a few simpler rental rigs out there that don't have processors, they just have simple amps with 100hz crossovers in them, or very simple 2-way rack mount crossovers and I want to be able to keep the <40hz material out of the subwoofers.

Any ideas how I can pull this off?

Why not just build the speaker level passive filters in the plans and install them permanently in the cabs?

Brent,

All my tops have x-overs in them. It's the subs that are the problem. Theres a 100hz LPF on the amps, but no HPF to protect from over-excursion and wasting power trying to reproduce sub-40hz material when the box simply cant do it.

That being said- a speaker level HPF is costly, and cost only grows when we talk about doing this for the entire fleet of rental subs (and full range cabinets). Rather than do that, I could make a bin full of these XLR/XLR with the HPF in them and slap them in the racks when the gears going out the door.

djtecthreat wrote:Brent,

All my tops have x-overs in them. It's the subs that are the problem. Theres a 100hz LPF on the amps, but no HPF to protect from over-excursion and wasting power trying to reproduce sub-40hz material when the box simply cant do it.

That being said- a speaker level HPF is costly, and cost only grows when we talk about doing this for the entire fleet of rental subs (and full range cabinets). Rather than do that, I could make a bin full of these XLR/XLR with the HPF in them and slap them in the racks when the gears going out the door.

Except its not that simple. You must know the impedances to calculate the crossover. Different amps have different impedances, along with the various devices driving them.

The speaker level hpf in the subs would be much more foolproof. the other option would be to find some inexpensive analog crossovers to do the same things, rack them with your amps, and install tamper covers.

Hi pass filters are usually incorporated into electronic crossovers and speaker management systems, often into the amps themselves.

The speaker level hpf in the subs would be much more foolproof

They'd cost a fortune, far more than a new crossover if his existing crossover doesn't have HP filtering.

It's the subs that are the problem. Theres a 100hz LPF on the amps, but no HPF to protect from over-excursion and wasting power trying to reproduce sub-40hz material when the box simply cant do it.

You should be using a real crossover. How are the tops high passed?

All tops have the passive filters assembly's (or in the case of my big name brand stuff, they already have crossovers installed).

Bill, in most cases I'm using a a real crossover on these systems. On occasion I will use the built in 100hz HPF for the tops, and built in 100hz LPF for the subs on rental systems. This works just fine, except for the lack of a HPF on the sub channel to cut out inaudible/non-producible material. None of my simple active crossovers (Rane AC22) have built in HPF for the subs. Thus- I need a solution rather than changing out 8 crossovers to models with built in HPF's.

djtecthreat wrote: I need a solution rather than changing out 8 crossovers to models with built in HPF's.

There is no passive solution, a 3rd order HP at 40Hz would cost you more than new crossovers to replace the Ranes.

dah well. Looks like I need to find a bulletproof crossover around/under $200 and start swapping my AC22's out.

For something cheap, versatile and tamper-proof check out MiniDSP kits...
I haven't played with mine enough to pass judgement, but have seen them mentioned a fair bit on other audio sites. Worth buying one to test out!

I'm betting you have no limiting then?

Better to replace the whole processing setup with "all in one" processing unit. Or XTI amps, or Lealnd can sell you Digimoda amps with it all preprogrammed for your cabs.

Eminence D-Fend Speaker Protection, this is not hpf/lpf but it will do the same to protect your speaker.

I'm not replacing perfectly good amps and retrofitting 30 rental stock cabs with $1000 digmoda amps, that's absolutely insane. I'm also not getting rid of perfectly good QSC amps to replace them with Crown XTI's.

That being said- No there is no limiting. Most of my rental stock is non-BFM cabs, and they tend to take a ton of power. I take a deposit on rentals, and it's in the contract that drivers will be replaced at the expense of the customer.

I'm not really 'interested' in replacing perfectly good crossovers for all-in-one units that cost twice as much for a pair of tops on sticks and a sub. Which is what I rent mostly, other times it's just 2 tops on sticks. I will however consider cycling out the crossovers for comparable models with a HPF on the sub section over a period of time, selling off my AC22's.

I'm familiar with MiniDSP, I like the idea of the product, but they do cost a bit for the balanced version in a housing. I really didn't like how they charge for preset configuration either.

I'm literally checking the D-Fend page everyday waiting for those to drop. No one has been able to answer the price question, they wont even tell me if they're between $30-100. If they're in the $40 price range then I will probably order 10 as soon as they drop and install them in my cabs. At that point HPF will be a lesser concern as the drivers will be protected from over-voltage anyway.

djtecthreat wrote:At that point HPF will be a lesser concern as the drivers will be protected from over-voltage anyway.

They won't. Excursion rises precipitously below the speakers design bandwidth, be it ours or any other speaker. If you don't high-pass then you would have to limit the voltage at a far lower figure.

I was looking at these for a different application, $40 crossover on a board you supply I/O and power connects.

http://www.marchandelec.com/xm1.html

Something like this work?
http://store.hlabs.com/pk4/store.pl?view_product=10