Active Crossovers

[Rudy81]

Hey, how about this beauty? Attenuation is apparently selectable!

http://www.guitarcenter.com/Audio-Technica-AT8202-Adjustable-Inline-Attenuator-100060116-i1391269.gc

[Coytee]

After just one afternoon playing around with the active filter in my room with my Khorns, I am convinced this is the way to go. The active crossover provides a much more coherent and cleaner sound with the time alignment and steeper crossovers. The nice thing is I don't have to wonder how it sounded one way or the other, I can just compare on the fly.

These are fighting words in some circles []

Regarding hiss...here's what I did... (bear in mind, I'm not familar with your amp)

I'm using some Crown K2's and they have external gain controls. I started near the speaker and worked backwards (towards CD)

I maxed the gains on the Crowns and heard some hiss. I started backing them off until I heard nothing (probably at 60% of max?). I then went to my Dx and turned it on (don't recall hearing anything). I last went to my preamp and turned it on. It too, has some output controls.

Now I know the basic levels I can have things set where I hear VERY little background hiss yet still have some horsepower available to me.

When I'm watching a show or doing something where I do not care about volume... I'll take my Crowns and put them on the 5th click (out of maybe 20 for full volume). This requires my preamp (Peach) go to just about 100% full volume for watching the news however.... NOW is when I see the lights on my Dx really lighting up.

I once asked Roy why when I first heard the Jubilees in Hope, the input lights on his Dx were lighting up like a Christmas tree and when I was playing mine, I had no 'blinky lights'. Now I understand why... I had fixed gains on that specific amp and it took VERY little input to make it very loud (I think that amp had a 1V input sensativity) Now that I can mix/match the gains I can tip the teeter-totter a bit in the direction of feeding the Dx a hotter signal without blasting myself out of the neighborhood.

[Rudy81]

Coytee: I am quickly learning about this gain balancing thing. You and DrWho are on the same page with the solution. I have the source signal as hot as I can get it, but my current setup does not allow to change the gain on the amp. I can do it, but I would use different amps that have gain knobs. The problem is that those gain knobs do not have any detents or markings. So, getting them all the same is next to impossible as DrWho mentioned. I already have experience with that issue and he is correct.

So, my hope is that I can add an XLR attenuator to the system and that should take care of the hiss and still leave me plenty of head room.

I was one of the ones who poo pooed active crossovers.....of course, I had never played with one either. I had ***-u-med it would degrade the signal. I have yet to get the system to where I can just sit and listen for problems due to the electronics in line with the drivers, but I can't hear anything obvious enough to make me want to put back the passive drivers. This hiss thing is not a 'problem' that can't be solved.

However, I am finding the flexibility afforded is tremendous. Once again I'm loving the journey and I appreciate all the help.

[Rudy81]

DrWho, I spent several hours running sweeps and taking readings. In order to save bandwidth, I am providing a link to a page containing all the results.

I decided to test both the JBL 2470 and K55 to see if the K55 would fill that dip in the crossover region. In fact, it did not and I now suspect I have a room mode right at that frequency. Moving the measurement mic around changes the dip somewhat, but does not totally get rid of it.

The JBL has similar low end characteristics but a much better high end.

I hope the graphs provide you with the kind of information you asked for in a prior post. Overall, I am pleased with the changes thus far. I have yet to balance the three channels, but am leaving that for last once I get the crossovers set properly. As you can see in the graphs, the tweeter is way attenuated compared to the mid and woofer.

I would love your observations and opinions. Here is the link: http://www.prontoweb.com/ActiveCrossover.htm

[Coytee]

I was one of the ones who poo pooed active crossovers.....of course, I had never played with one either. I had ***-u-med it would degrade the signal. I have yet to get the system to where I can just sit and listen for problems due to the electronics in line with the drivers, but I can't hear anything obvious enough to make me want to put back the passive drivers

Welcome..... to the dark side..... [<)]

[Coytee]

Darn double post bit me in the hiney! [:|]

OH well... it's here, may as well use it!

The problem is that those gain knobs do not have any detents or markings. So, getting them all the same is next to impossible as DrWho mentioned

Yes, I agree. I have another amp that can be configured between 2, 3 or 4 channels. Each channel has a gain knob but... none of them have a detent so it's still a bit of a guessing game.

Drives me nuts and one reason I like the Crown's

[Rudy81]

Have any of you ever used Behringer crossovers? I have been asking around about the hiss issue and asked the amp manufacturer. He suggested the Behringer product. I don't know where the issue is, but it sure would be nice to get rid of the hiss.

[6l6gc]

I'v been lurking for a while thought I'd join in, I use a Behringer deq2496 and a dcx2496 for bi amping khorns,

I also stumbled across a 450hz dip on the bass bin making it rather difficult to smoothly cross at that point if using steep slopes

I ended up with either overlapping steep slopes, or 450hz freq with 12gb gentle slopes. however with time and with more iterations, I have now ended up crossing at 607hz using 48db slopes with a little eq help.

this sounds more natural to my ears with music, and during testing white noise sounds more neutral to me , I do suspect that the bass horn freq resp is not so smooth beyond 400hz, ( I run sweeps by ear but can't plot a graph), despite that in my small room and to my ears, this is currently the preferred setting for now. when using the mid to cover down to 400hz-, it doesn't sound right to me for some reason. but I'm still experimenting.

As a side note I also found a very deep dip at 125hz.

[Rudy81]

Regarding hiss...here's what I did... (bear in mind, I'm not familar with your amp)

I'm using some Crown K2's and they have external gain controls. I started near the speaker and worked backwards (towards CD)

I maxed the gains on the Crowns and heard some hiss. I started backing them off until I heard nothing (probably at 60% of max?). I then went to my Dx and turned it on (don't recall hearing anything). I last went to my preamp and turned it on. It too, has some output controls.

Now I know the basic levels I can have things set where I hear VERY little background hiss yet still have some horsepower available to me.

When I'm watching a show or doing something where I do not care about volume... I'll take my Crowns and put them on the 5th click (out of maybe 20 for full volume). This requires my preamp (Peach) go to just about 100% full volume for watching the news however.... NOW is when I see the lights on my Dx really lighting up.

I once asked Roy why when I first heard the Jubilees in Hope, the input lights on his Dx were lighting up like a Christmas tree and when I was playing mine, I had no 'blinky lights'. Now I understand why... I had fixed gains on that specific amp and it took VERY little input to make it very loud (I think that amp had a 1V input sensativity) Now that I can mix/match the gains I can tip the teeter-totter a bit in the direction of feeding the Dx a hotter signal without blasting myself out of the neighborhood.

I have been working on this hiss thing all afternoon. I now know I won't be able to live with the hiss...it's just me, I don't know why it bothers me since I can't hear it with most music.

It is definately the DC-ONE's noise floor since I can't make it go away when I mute all the channels. As long as the DC-ONE is powered, I get hiss. I am hoping I can solve this, otherwise, it will have been all for nothing. I was going to try the XLR attenuators to see if that made a difference, but I have to order them online, nobody stocks them locally. That makes returning them if they don't work more of a pain. []

[Rudy81]

I'v been lurking for a while thought I'd join in, I use a Behringer deq2496 and a dcx2496 for bi amping khorns,

I also stumbled across a 450hz dip on the bass bin making it rather difficult to smoothly cross at that point if using steep slopes

I ended up with either overlapping steep slopes, or 450hz freq with 12gb gentle slopes. however with time and with more iterations, I have now ended up crossing at 607hz using 48db slopes with a little eq help.

this sounds more natural to my ears with music, and during testing white noise sounds more neutral to me , I do suspect that the bass horn freq resp is not so smooth beyond 400hz, ( I run sweeps by ear but can't plot a graph), despite that in my small room and to my ears, this is currently the preferred setting for now. when using the mid to cover down to 400hz-, it doesn't sound right to me for some reason. but I'm still experimenting.

As a side note I also found a very deep dip at 125hz.

Thank you for chiming in! If I can manage to get a handle on this 'hiss' problem, I would love to work on a better crossover method for the bass bin. I now know why Roy and PWK were working on a Khorn follow on.

Do you notice the hiss I'm talking about?

[Coytee]

It is definately the DC-ONE's noise floor since I can't make it go away when I mute all the channels. As long as the DC-ONE is powered, I get hiss. I am hoping I can solve this, otherwise, it will have been all for nothing.

I've not heard back from Brian lately, I speculate he's not even opened the box that he got with my Dx38 in it.

That said... don't pull the plug quite yet. Perhaps it might be worth the experiment of still sending you the Dx when he's done with it so you can then do a side by side with the Dx on one side (doing 3-way) and your DC One on the other side?

Just an idea. Won't cost you much more than simply shipping it back to me to give it a whirl.

Oh... if I remember correctly... DC-ONE... made in China. Dx38... made in Germany.

Just mentioning it.

[Y]

[Rudy81]

Coytee: Definately worth a try! I am pumped about the flexibility the system offers, but I can't deal with a 'noisy' system.

[mikebse2a3]

I have been working on this hiss thing all afternoon. I now know I won't be able to live with the hiss...it's just me, I don't know why it bothers me since I can't hear it with most music.

It is definately the DC-ONE's noise floor since I can't make it go away when I mute all the channels. As long as the DC-ONE is powered, I get hiss. I am hoping I can solve this, otherwise, it will have been all for nothing. I was going to try the XLR attenuators to see if that made a difference, but I have to order them online, nobody stocks them locally. That makes returning them if they don't work more of a pain.

He Rudy81

You can solve the hiss by attenuating the drive to your amplifiers and this will allow you to drive the EV correctly.

By the way some attenuators I saw posted by you are designed for Mic use are not what you want because of their designed impedances.

What is the input impedance of your amplifiers balanced and also unbalanced inputs?

What is the input sensitivity voltage for both balanced and unbalanced inputs of your amplifier?

What is your amplifiers model number?

Also if you have RCA style attenuators with the proper impedance why don't you temporarely try this and see what the results are.

I convert to unbalanced RCA for my amplifiers and my system is dead silent...!

Rudy81 this can be solved without messing with the EV's internal design.

mike tn[]

edit: Rudy81 the EV isn't your problem and Anytime 104db efficient loudspeakers systems are used it is not unusual to have to much gain in a system because equipment and amplifier designers are assuming the typical less efficient speakers are being used.

[Rudy81]

mike tn: Yes, some of those attenuators are designed for microphones, so I was not sure if they would work. Although I am very much the novice, as you can tell, I am pretty sure that in order for this to work, I have to reduce the gain on the signal coming from the EV to the amp. The amps are Parasound HALO A23 and A52.

If I got to unbalanced RCA, I will have to get some XLR to RCA cables or adapters. That is one option. Sadly, I don't have any on hand.

So, for now I'm kind of stuck a bit. I will see what I can righ up to test the gain theory.

[mikebse2a3]

Just hang in there Rudy81...![]

There's nothing here that I've seen you post that can't be solved with a little patience.

mike tn

[cfelliot]

If I read your posts and equipment list correctly, you are driving the tweeter with a 125W amplifier. They're 100+ db at 1 watt, no wonder the noise floor is audible.

I think that once you attenuate the signal into the amp it will sound fine.

I'm following your posts with interest because I'm trying to decide whether to upgrade my passives or go active.

Post up your settings file on your site. I have the DC-One program loaded and would love to look at your settings.

Chuck

[6l6gc]

I do not have any hiss, (there is the normal hiss you get if you stick your ear against the mid or tweeter) but nothing abnormal.

The signal path (or I should say data path) goes digitally from player (a pc) via SPDIF optic cable into the deq unit and then after eq'ing , it continues digitally via XLR cable to the dcx cross, the dcx analog signal then continues directly into the amps. the amps gains are set to the minimum required to achieve the max spl I want to listen to when all the other signals in the chain are maxed, I set it in the vicinity of hearing damage levels at about 110db spl. so the signal is kept in the digital domain without any conversions for as long as possible.

[Islander]

Do you notice the hiss I'm talking about?

I get a little bit of hiss with the Dx38 output knobs in the 12 o'clock (-6dB) position, but it's only audible within about 3 feet of the speakers and not at all from the listening position, so it doesn't bother me.

Turning the output knobs to the 9 o'clock position gives about 24dB of attenuation and pretty well makes the hiss disappear altogether, but there's a bit less headroom like that, so I usually leave the knobs in the detented -6dB position.

[Rudy81]

mike, DrWho and everyone else that has helped. I truly want to thank you guys for holding my hand throught this process. The reality is you guys have made this a pretty easy process to what it would have been without your most able assistance. I can't thank you guys enough.

Chuck: I will keep you posted. As you have seen by this thread, I'm not shy about asking for help. You are right on the money with your analysis. I just tested it and it works great. Here is what I did.

Based on the comments above I figured I needed to be able to reduce the gain on my amplifier since what I am hearing is the noise floor on the EV output. I remembered that my 2 channel amp, the A23, has gain knobs that I guessed would also affect the balanced section. I just finished swapping all the cabling so I could hook up the mid driver and tweeter to that amp. Guess what, if I reduce the gain in the amp by about half, the drivers are silent!

Now, what I will need to do is to get some XLR to RCA cables. This will allow me to use the A23 and a third Parasound amp I have that has only RCA inputs, BUT has gain knobs. The problem is going to be setting the gain knobs all the same! Otherwise, I can get some 6dB or 10dB attenuators from Goldenjacks and I should be in business.

Yeah!

Sorry for all the posts guys, but this is all new to me and I needed a lot of help. Here's a beer for you guys!

[mikebse2a3]

I remembered that my 2 channel amp, the A23, has gain knobs that I guessed would also affect the balanced section. I just finished swapping all the cabling so I could hook up the mid driver and tweeter to that amp. Guess what, if I reduce the gain in the amp by about half, the drivers are silent!

I had just finished reading about your amplifiers options and was going to suggest you tweek those A23 gains.

Adjusting all the gains to match really want be to hard.

mike tn