[Freo-1]

Wanted to get some input/feedback on active crossovers.  Since my two channel audio setup is currently using low(er) wattage amps, was looking to try an active crossover to see if I could get a little more dynamics and clarity from the front speakers.  The  one I tried did not work at all, as it seemed to muffle the playback.

So, who has them as part of their system, and what are you using?   Keen to find out if there are folks out there who have obtained improved performance from using them.

[JohnR]

When you say you tried one and it didn't work out, how were you using it? As a crossover, highpass filter, ...?

[Speedskater]

Speaker designer skill is always more important than technology used.

[playntheblues]

I also am looking into active xovers, from one end of the spectrum to the other.  Either the new DEQX HDP-4 or have Tom Tutay in Fl. build tube xovers.  I would love to hear any thoughts from those of you who are or have used active xovers.
Guy

[JerryLove]

I'm using Behringer DCX's on a pair of 4-way towers.

[PRELUDE]

Wanted to get some input/feedback on active crossovers.  Since my two channel audio setup is currently using low(er) wattage amps, was looking to try an active crossover to see if I could get a little more dynamics and clarity from the front speakers.  The  one I tried did not work at all, as it seemed to muffle the playback.

So, who has them as part of their system, and what are you using?   Keen to find out if there are folks out there who have obtained improved performance from using them.

Hi Freo-1
The way you asked your question is not going to help you to improve anything.If I were you,I would go ahead and change the topic of your question to:
How can I put an active system up at reasonable cost?
Just to say I used an active crossover is not enough info for us to help you.We should know 3 things up front.
1-What did you use?
2-How did you use it?
3-What you do not like about it?
If you like to see what other people are using you might look at this thread here:
http://www.audiocircle.com/index.php?topic=94674.msg946920#msg946920

[Ethan Winer]

So, who has them as part of their system, and what are you using?

I'm a huge fan of bi-amping, though what I have might be overkill for most people.

My speakers are JBL 4430s - these are large old-school pro studio monitors with a 15 inch woofer and horn. I use a Rane active crossover, which feeds two Crown power amps totaling just over 1 KW. This system plays very loud and stays very clean at all levels.

--Ethan

[Speedskater]

The three great virtues of a "DSP" type active crossover for us DIY designers are:

1] You can quickly change a crossover parameter. Slope or Frequency.
2] You can program in several different possible crossover options as scenes. Then have a friend randomly change scenes and you do blind tests with no expectations.
3] The cost of changing values is zero.  New passive crossover components are expensive. (Dedicated active crossover components aren't expensive, but it still can be a pain)

[DaveC113]

Good topic.

I am also interested in attempting to highpass my single driver speakers.

The 1st thing I'm trying is adjusting the RC filter between the 2 stages of my amplifier for a F3 of 30-40 Hz, I have a few resistor values so I can try for 30, 35 and 40 Hz. I don't want to make the F3 too high or I think it might affect the quality of the mid bass, which wouldn't be a good trade-off...

Also, miniDSP might be a good solution for this, and could also do room correction eq as welll...

[Rocket_Ronny]

In a conversation I had with Roger Sanders he said the Behringer digital crossover he uses in his electrostats is among the best measuring piece of kit he has seen and that the unit is very transparent, even going analogue in and out.

In another conversation I had with Jim Smith, the author of "Get Better Sound", he said that he has a great deal of active systems people have set up and MOST of them did not perform that well. Something to be said for all the labor of love that designers go through in their passive networks.

A crossover point near 700 hz is a great place to biamp if you can, Maggy 1.7s anyone, as it's near the middle for splitting power. Using 2 100 watt amps will not just act like 200 watts, but more like 400.

Myself, although I have not actively biamped I sure like the idea. Only downside, besides the cost and effort involved, is the hassle of a more complicated system.

Rocket_Ronny

[Freo-1]

I wanted to get the topic off the ground, so I left it a bit vague by design.  I tried a Symmetry two way active crossover, set to 80Hz.  The high pass sounded muffled, flat, and 2D.  I'm sure the crossover had seen better days, but it just did not sound right.  It was as if there were two separate stereos playing the same music.
 
For now, I am working around the bass integration issue by readjusting the settings on my subwoofer (Genesis G928).  I set the crossover point at 90Hz, and reversed the  phase on the subwoofer, and was able to smooth out the mid-bass bloat quite a bit.  Still would like to see if a better crossover would improve the overall sound. 

I'm using a First Watt M2 amp, and Cary Silver Oak Model One speakers.  Soon, I'll by using a pair of tube mono blocks on the Carys that sport 1625 output tubes (12 volt 805 tubes), and 12SN7 input tubes. 

[JohnR]

It sounds like you're really asking about bass integration. A simple passive highpass filter on the mains, a DSP on the sub, and measuring gear to get it set up properly, would be a good approach, from what you have described.

I'm assuming you're not interested in taking the system fully active (ie. removing the existing passive crossover). But if the mains as they are are lacking "clarity and dynamics" then just highpassing them may not make too much of a difference.

[Freo-1]

You are correct about my wanting to smoothly integrate a active subwoofer with my main speakers.  However, I am interested in looking at a two way active crossover (zero db gain) for both feeds (low pass and high pass).   

In theory, the active two way crossover should free up the mains to be driven to increased clarity with a lower powered setup.

[jimdgoulding]

Nice topic.  I use factory active bi-amped speakers.  The networks are less complicated cause the amps drive the speaker direct AFTER the crossover rather than before and can operate the drivers in time.  Of course. before that I used single driver speakers so I'm kinda spoiled.

[JohnR]

You are correct about my wanting to smoothly integrate a active subwoofer with my main speakers.  However, I am interested in looking at a two way active crossover (zero db gain) for both feeds (low pass and high pass).   

In theory, the active two way crossover should free up the mains to be driven to increased clarity with a lower powered setup.

With most music, a highpass at 80 Hz won't make all that much difference to power. The mid-power point is I believe typically said to be around 250 Hz. The main advantage of highpassing at e.g. 80 Hz is to reduce excursion on the woofer. (And to simplify sub integration)

I don't know the specifics of your speaker but most similar ones have a baffle-step compensation built into the crossover, of 3 to 6 dB. So above a few hundred Hz, and up to the crossover to the tweeter, a good chunk of power is being dissipated in the crossover. A fully-active solution will claim that power back.

Your amp has an input sensitivity of 3V for full power output. Some DSP-based crossovers will clip below that level.

These are just some points to be aware of

[sts9fan]

If you are just using it on a subwoofer(s) I think the MiniDSP is great. I am currently doing just that to get rid of a pretty big null.
Of course it does require a separate measurement set up.

[ehoove]

I use 2 active crossovers. I used a Behringer DCX2496 for my Tri-amped Magnapan MGIIIa's (Maple Frames and braced stands, and a NHT X1 crossover for my NHT W2 subwoofer cabinets. The Behringer is an amazingly flexible crossover that stores various setups internally as well as via a card which makes tweaking very easy. I run the MGIIIa's as standalone speakers using the DCX2496 and use the X1 crossover and W2 subs to fortify the bottom end from 43hz down. This allows me to use the subs as needed, and makes the Magnapans able to present any genre of music with ease including Rock. The system is dead quiet and offers 900 Watts RMS to each MGIIIa, so headroom is not an issue. 
Regards,
Jim

[Scott F.]

Freo,

was looking to try an active crossover to see if I could get a little more dynamics and clarity from the front speakers

Unfortunately, the way you are looking to utilize a crossover, you aren't going to achieve your primary objectives. By cutting off your Carys below (say) 80Hz, you are only freeing up some headroom on the amp you plan to use to drive them. Inserting an active crossover is literally inserting more electronics in the signal chain. You will experience a degradation in the sound quality. There is no was around it. On the other hanmd, headroom is a very good thing.

That said, if you want to bypass the crossover in the Cary speakers, that is when you will achieve your goals. There are numerous issues you run into when you try something like this. First and probably the largest is any baffle step correction the designer factored into his passive design. The typical active XO won't compensate for this. The you get into impedance correction, time and phase correction. Many of the DSP based actives can handle the time and phase corrections.

You mentioned a zero gain active crossover. Unless I'm misunderstanding your terminology, I don't believe an active crossover like that is avaiaible. An active crossover is just that, active. You have gain and detent built into the design on each octave band covered.

Now, if you are looking for a passive to use in a line level application, I'd say try one of these;
http://store.hlabs.com/pk4/store.pl?section=9
This will plug right into the back of your preamp. It doesn't get much easier. The cost seems pretty reasonable. I've not heard one but I've read relatively positive things about them.

I've been doing active for the past 15 years or so. All of my speakers have been DIY. I've heard a few where the guys have bypassed the factory passive XO and gone with an active (mostly Maggies). All had very nice increases in dynamics and clarity.

I'm not a big fan of the DSP/opamp based XOs. I prefer a traditional FET based XO like my Pioneer SF-850. With a few updates and tweaks, this XO is super transparent and minimally imparts a sonic signature into the chain. I own, have owned or listened nearly every active XO out there. I settled on the Pioneer.

[Davey]

"Active" simply means powered circuitry.  Whether the circuit has voltage gain (negative or positive) or is unity (zero) gain is up to the designer.  I think you'll find that all commercial active crossovers are centered around a unity gain architecture.  Relative gain adjustment on individual outputs is, of course, included since this is one of the many features easily implemented.

Whether or not these crossovers contribute to "signal degradation" is a question.  But relative to other items in your signal chain, active crossovers should have minimal degradation.  How much signal degradation does a vacuum tube circuit have?  Or a passive, speaker-level crossover, (that will be removed when making a change like this?)  Or a diamond following a primitive groove in vinyl? 

Much ignorant evaluation regarding active crossovers has happened in the audio world.  Almost always, an apples-to-orange comparison was made (with incorrect conclusion) relative to using the original speaker crossovers, which were designed with a specific objective using non-generic slopes.

Speedskater is correct.  Designer skill is always more important than the technology used.
However, all other things being equal, there is no possibility that an active crossover can be out-performed by a speaker-level passive crossover.   A crossover ahead of the power amps is just a superior configuration.  Most folks outside of the insane "high-end" audio "industry" have known this for years. 

Cheers,

Dave.

[JerryLove]

Agreed. Active crossovers (instead of passive ones) offer superior and more numerous options to passive crossovers; though they still require the same types of skills to setup that passives do to design.

They also offer greater flexibility: allowing one to correct for a room or even just listening preferences and then change back at will.

In the more simple hi/low-pass filter he wants to insert in order to run a sub (don't most subs have these built in so you can just put them in the chain?), you don't have those advantages; but there are still up-sides (the most obvious is that handing full range to a sub would be a terrible idea: so at least the low-pass filter there).

Very fond of my DCX's, even if I'm not fond of needing 4 amps to run a speaker.