Need clarification of active crossovers/speakers

[mojopin]

Hi,

This is a newbie question and like many others I have been trying to digest all the info on this site but it is quite a bit.

Anyhow, when people build a speaker that uses active crossovers how much does the box design matter? Or approaching the question from a different angle, can I pick drivers that I like and put them in an enclosure and then hope that crossovers and eq can flatten out the response? The only tidbit I found was that someone put a cap on the tweeter to protect it just in case which was a concern of mine. Is this what people usually do?

Thanks!

 

[pinkmouse]

You can adjust box response to a certain extent with EQ and crossover electronics, but it is a much better strategy to get the box and drivers working well together first, then think about EQ. So to get the best results in the most straightforward way, the answer is really no.

 

[mojopin]

Thanks for the reply! What I should have asked is: Can I take a proven design that someone has posted like Zaph or Troels Gravesen and build it minus the passive crossover and replicate it with an active crossover?

Of course, if I have gone that far why not build the crossover? I have zero electronics skill but that isn't much of an excuse.

..and once again my head does another lap on the diyaudio merry-go-round..

 

[MaVo]

I believe you try to figure out which loudspeaker is the best for you. My advice would be, dont bother with the little details like crossover design right now. Better you try to get a basic understanding of the different designs out there. Every design has its own application, you need to find the one that gives the best results in your listening environment according to your taste.

Some things to read up could be stuff about speaker/room interaction, the enclosures like open baffle, closed box, horn etc. and different driver types like low sensitivity hifi, fullrange, professional and so on.

I think mr. linkwitz knows alot about this stuff, his website covers alot of ground, even if its complicated at first.
http://www.linkwitzlab.com/

Have fun reading

 

[Daveis]

What I should have asked is: Can I take a proven design that someone has posted like Zaph or Troels Gravesen and build it minus the passive crossover and replicate it with an active crossover?

Of course, if I have gone that far why not build the crossover? I have zero electronics skill but that isn't much of an excuse.

Active crossovers are fun for experimenting with a wide range of drivers, crossover slopes in a short amount of time without having to build the passive crossover. It aids in "dialing" in the sound you want. Once you have that sound, its probably easier to just build the passive crossover based on things you learned from your active experiments.

Active crossovers can allow you to mix drivers that really have mismatched impedance/sensitivities. They sound a little more dynamic, but not enough IMHO to warrant the added expense of the amplifiers.

Soldering large components is easy. Its the surface mount stuff that's hard. I wear thick glasses, can't see well, and have shaky hands. I can still solder large crossover sized components.

I don't bother soldering the end that actually connects to the speaker. If I was building a permanent speaker that was going to last for 20 years I'd solder it (maybe).

Anyways, I'd encourage you to learn to solder large components.

 

[BHTX]

I think you and I are in a very similar boat here...

Although I might not be completely new to loudspeakers in general, as well as many of the basic concepts and designs, I've been obsessed with this kinda stuff since I was able to walk...but I still haven't actually built anything major. Never designed a crossover, don't know the first thing about woodworking or veneering, never even put together a kit. Mainly, I just know a pretty good deal about the vast majority of loudspeaker products available on the market, including both retail hifi and DIY. So, after a lot of research and thinking, what I've finally decided to do after years of going in circles with the "high-end" BS equipment from ripoff hi-fi stores, is start out building my own simple stuff, without actually designing it completely. For example, I just purchased a set of coaxial drivers from a respected manufacturer with their matching pre-made passive crossovers from a well-known internet retailer. The passive crossovers aren't anything special, pretty basic it seems, and don't include baffle step compensation or anything like that...but they were designed for these specific drivers by the retailer. These speakers should work well in my environment (a smaller living room), sitting a fairly close distance to the speakers. These speakers are also sold by the same retailer as a complete kit with finished vented enclosures with pre-cut baffles and hardware, where pretty much all you'd have to do is get your screw driver and spend a few minutes putting it together. But instead, since I (or anyone) can buy just the drivers themselves, the drivers and their crossovers, or the complete kit with cabinets...I chose to purchase only the drivers with crossovers in order to change things up a bit for my personal tastes, and to attempt to obtain what I want out of the system, as well as do some learning and experimenting around. So, I'll have smaller sealed cabinets made by someone else for the coaxial drivers, and actively cross them to some good woofers in a custom built sealed enclosure with LT, and use a tad bit of EQ for all of it as needed. Once that's done, I'll purchase the rest of the drivers and have cabinets made for center/rear channels to make a complete 7.1 setup. The toughest part of it all so far is simply finding someone to build the enclosures for me, and I honestly think this is a large part of the reason why I've waited so long to build anything. Previously, I had met someone who I thought was going to help, but it didn't work out for various reasons. Now, months later, I just met another customer the other night during my visit at the local hardware store. We talked for a couple of hours straight about all kinds of stuff, including all the work he'd done over the last few years for various people...like complete house remodeling, $50k kitchen cabinets...stuff like that. He said he had plenty of proof at home for me to verify his experience. So, I explained to him what I wanted to have done, and he'd be more than willing to help for a very reasonable price. He's supposed to be calling me tomorrow afternoon to discuss the project further, and then show me some of his woodworking skills at his shop. On top of the difficulties caused by my lack of woodworking experience, tools, etc... I'm also in the process of selling tons of hi-fi equipment, most of which I never even used. I'll be losing quite a bit of money, but I think I'll be happier in the long run. So, with all that said... if you have any experience at all in woodworking, have tools available, or even help readily available to you... I think you're probably ahead of a lot of people starting out, such as myself.

Anyway, I wouldn't normally suggest taking a well thought-out design from someone like Zaph or Gravesen or Linkwitz or whoever, and making big changes to it. I think a lot of people that do this end up not being satisfied with the end result, and then wonder what they did wrong because it doesn't sound right. But on the other hand, with a little thought and research, you can can start out by finding something relatively simple that some might not consider the absolute greatest thing in the world, yet a large portion of it was designed by YOU and made to fit YOUR needs, and works extremely well for your intended application... Something that small specific changes can be made to fit your personal neeeds and tastes without causing problems and ruining an original design, and can be tweaked as you continue to learn more and figure things out...to the point where it sounds REALLY good in the "end" (ie: I could study crossover design in the future and redesign and upgrade the existing crossovers that I purchased for the coaxial drivers, or find and use someone else's design for these speakers, and/or simply tweak/upgrade the active crossover and EQ, make improvements to the enclosures, read up on room acoustics and make my own DIY room treatments and then tweak that, etc etc)... But chances are, once you get started, you won't be able to stop. Therefore, use everything you did during all that time spent on attempts to make your design better for you as a learning experience for any future projects.

 

[Brett]

You can adjust box response to a certain extent with EQ and crossover electronics, but it is a much better strategy to get the box and drivers working well together first, then think about EQ. So to get the best results in the most straightforward way, the answer is really no.

I get the design as correct as possible within my specification, and just use the xovers as frequrncy dividers with maybe BSC and compensation for CD flares.

 

[mojopin]

Thanks for the replies. Thats quite a post BHTX. I'm actually residing in the lone star state too..houston. Need to update my location.

Anyhow, while my woodworking skills are pretty much none I am not afraid of trying it. I did build a bandpass sub for my car a decade ago when I was in high school. That sounded great until the speaker blew..whoops! I just know that this next speaker will probably be something I have to live with for the next five to ten years. It should be great but not expensive. I figure I would be happy spending up to 1000$. I am a musician and would be using these as kind-of-near-field monitors. I also just snatched up four 18" jbl speakers with enclosures for super cheap at an auction. They just needed some new surrounds which is almost done. I am going to put one in each corner and see how that sounds. I read that together they could help smooth out the peaks in the room. I guess the reason active crossovers are appealing is because I am going to have to buy one anyhow for these speakers. Right now I am just using separate outs on my computer with a low-pass eq plugin. This is not a solution as I like to use a REAL knob for volume. Anyways, I think it is critical to have flat response from my speakers done to at least 30 hz. Why do some designs feel it is okay to only have the top end response go to 15k? I can hear up to 18k so a good tweeter is also important. I have listened to full range speakers and heard the best midrange from them. I am thinking that a good two-way speaker good integrate with what I have since they only need to reach down to about 75hz. Does anyone know of companies that will build a crossover for me from a schematic? Does madisound do this? I don't want to mess up and I am ready to get on with the music! Thanks for reading...

 

[saturntube]

Marchand Electronics has everything you will need or they can build it for you, passive line level XO, active SS or tubes etc.

You can also get a subamp with XO included, they work just fine!
Madisound has them up to 100hz or Parts express Bash goes up to 150hz and there are some Dayton that will go up to 200hz.


You can try a Fostex Fullrange driver in a box for mids and some compressio driver and horns from 1khz up...hard to beat.