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Keeping it simple with networks


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I have been using an active crossover for some time (minidsp).  The latest project I have worked on, Belle bass bin/prv horns with Ev drivers, in a two configuration.  Has forced me to play around a bit.  First I had to turn off Audessey, then a couple of weeks ago I had to remove all eq settings from the minidsp.  Tonight I even changed the crossover setting to just 600hz.  After spl matching all drivers at the sweet spot.  Things are really sounding good. 

 

I remember DeanG giving me crap about playing around with an active some time ago.  I wonder if he was referring to all the crap I was attempting to implement into the system ( as far as equing goes).  I have often wondered how some passives would do me good on most of my experiments.  My problem is dropping the $300-$400 minimal on passives, to find out they won't work.  Especially when decent actives can be had for that amount.
 

I don't want to turn this into a passives or actives are better than one or the other. But I would like to know how simple passives are compared to equing and time aligning with actives.  This has been covered before, but how can we keep it simple to sound good.   Are there lower cost passive designs that will sound as good if not better than setting a crossover and the spl level of each driver?

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Nick, I have only used passives, and only built one set, so I don't know if I am much help... but, I really understand the reason for actives. Fairly easy time/ level/ eq adjustment of drivers. If always tweaking and changing parts, this is a no brainer.

But my system got put together, has a single pair of amps and I'm done. I come home and listen to the music. I don't even remember the slopes on my crossovers. Maybe I was lucky and hit that synergy with my cmponents first time, but I get carried away (well, i did until i sold the LS).

Bruce

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Especially when decent actives can be had for that amount.

 

Perhaps you should try a used Yamaha SP2060 or a XIlica XP series active for that kind of money: the difference in SQ would be significant relative to the miniDSP.

 

Chris

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Especially when decent actives can be had for that amount.

 

Perhaps you should try a used Yamaha SP2060 or a XIlica XP series active for that kind of money: the difference in SQ would be significant relative to the miniDSP.

 

Chris

 

That is one of the reasons I find it hard to spend the money on passives.  However, where is the simplicity at on passives that may be implemented on an active?  I have been looking at one of the products from Ashly. 

 

From my understanding of passives and when they are designed.  They are designed with the delays, equing and what ever else is needed to bring the system to life.  Now one could say that networks are not universal, hence why you see specific drivers with specific networks.  However, people aren't sticking to that theory.  Take the DHA2, Criites A/4500, any of Deans or Al's networks.  People are using these with mix and match horns/drivers with claimed success.   If there is a basic theory to every network, such as crossover point, delay, maybe some basic equing.  Then why couldn't these same "simple" or "basic" ideas be implemented into an active?  I get why we would want to use and active.   We then have total control over our system in our rooms. 

Edited by The Dude
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Nick, I have only used passives, and only built one set, so I don't know if I am much help... but, I really understand the reason for actives. Fairly easy time/ level/ eq adjustment of drivers. If always tweaking and changing parts, this is a no brainer.

But my system got put together, has a single pair of amps and I'm done. I come home and listen to the music. I don't even remember the slopes on my crossovers. Maybe I was lucky and hit that synergy with my cmponents first time, but I get carried away (well, i did until i sold the LS).

Bruce

This video

 

 

Is the whole reason, I wanted to go active.  Though my goal isn't to go as far as this, it is however to get as close as possible or at least with in my means.   Yeah its going to be comparing a bologna sandwich to prime rib. However I always have this thought, how will it sound like this? How would it sound if I did this.  Maybe this is the fun parts of the hobby.  However I just don't have the funds to play that much, and am always trying to find a lower cost alternative. 

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From my understanding of passives and when they are designed. They are designed with the delays, equing and what ever else is needed to bring the system to life.

I wish this were true.

 

Passives are always designed without consideration of HF-LF phase shift correction (about 90 degrees of delay for every "order" of the crossover filters). EQ is rarely used in passives, although Klipsch's older crossovers are using some form of EQ using impedance swings on the HF sections (avoiding the use of in-series resistors) but presenting a more difficult load for your amplifier to drive.

 

However, there typically is no other degradation of SQ due to the digital or analog sections that you often see in low cost active crossovers.

 

I'd recommend DIY passives if passives is what you're wanting to try out.  The schematics for most Klipsch designs are typically posted on this site, and you'll save a bundle over paying third parties to do it for you (just don't get crazy with the capacitor prices). 

 

The only portion of the passive crossover DIY tasks that I find a little tedious is choke (inductor) winding.  But once you get the right tools to help maintain the tension and the progressing winding lead angle for smooth coil lay-downs, all you have to do is measure the length of wire, and use a good winding bobbin (i.e., choke core) to hold everything in place.   I'm sure that Parts Express now has inexpensive measurement kits to measure the component values (resistance, inductance, capacitance) and the overall FR of the passives after assembly.

 

Chris

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Passives are always designed without consideration of HF-LF phase shift correction (about 90 degrees of delay for every "order" of the crossover filters). EQ is rarely used in passives,

 

With that being said, then would using the active as just a crossover, with no equing, maybe a little delay and maybe some phase shift (if needed). Be the same as a passive?

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Not quite - you're still having to go through the A/D-D/A with the downstream analog section to do a little amplification and conditioning of the output impedance.  In that respect, if you're not concerned about time alignment and EQing the frequency response flat, then passives are probably the way to go, discounting analog active crossovers, of course--which is another subject entirely.

 

Chris

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The email feature on my website has been disabled for quite some time. Last week I made the decision to take down the website. My physical condition doesn't allow me to build like I used to. I accept work on a limited basis.

Every horn and driver combination produces a different response. Therefore, you can't just use an off the shelf stock Klipsch network and expect optimal results. Active filtering is a powerful tool - but you need to know a few things about your set up, which can only be learned through measurements.

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Passives are always designed without consideration of HF-LF phase shift correction (about 90 degrees of delay for every "order" of the crossover filters). EQ is rarely used in passives, although Klipsch's older crossovers are using some form of EQ using impedance swings on the HF sections (avoiding the use of in-series resistors) but presenting a more difficult load for your amplifier to drive.

 

Actually, you can correct for HF-LF phase shift and everything else in passives, but then it really is tied to specific drivers, and the complexity and cost goes up. For an example, look up Dennis Murphy's crossover design for the JBL 4311. So... even though the simpler crossovers like the A/AA/DHA2 can be used on some varied parts, changing too much and you need a complete redesign.

 

I think Dean has pointed out, accurately, that you can't do either of these things on the cheap.

 

Bruce

 

ps... Deano, I left a message for you on Ethan's phone... you're being sly, no?

Edited by Marvel
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So... even though the simpler crossovers...can be used on some varied parts, changing too much and you need a complete redesign...you can't do either of these things on the cheap.

 

 

 The crossover must be inaudible

The crossover must be inaudible on program material. This also implies that the power response of the two drivers must be similar in the crossover region, and that requires special attention during the loudspeaker's concept and design phases.

 

Crossovers may be implemented either as passive RLC networks, as active filters with operational amplifier circuits or with DSP engines and software. The only excuse for passive crossovers is their low cost. Their behavior changes with the signal level dependent dynamics of the drivers. They block the power amplifier from taking maximum control over the voice coil motion. They are a waste of time, if accuracy of reproduction is the goal.

 

Siegfried Linkwitz

 

This is a pretty good explanation of the situation: once you start to do passive crossovers "well enough", they cost too much.  That's the problem.

 

Chris

Edited by Chris A
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Do you run a capacitor between your amplifier and those hideously expensive TAD drivers?

The Type AA network has six parts and no resistors - the horns themselves determine the crossover points - it's a brilliant design - and the sound is very good!

All designers follow their own path - right down into the rabbit hole.

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I wonder what people think of back loaded cabinets with single full range drivers. That seems pretty simple and pretty brilliant to me. Other than lack of bass below about 65Hz, I don't really see any disadvantages. Adding a sub would make one a 2 way capable of 20Hz to 20Khz.

 

What are the considerations of this kind of setup, and forgoing the networks all together except the sub passes.

 

Here's a little article on the back loaded project. http://diyaudioprojects.com/Speakers/Fostex-FE206En-Back-Loaded-Horn-Speakers/

Edited by mustang guy
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