Going active with Altecs!

[chopsrr]

So that's the plan anyways.

I am going to be ordering a Behringer SUPER-X PRO CX3400 electronic crossover in the next couple of weeks.

I have a Crown D-75A amp coming as well to power the 902-8B drivers. I will be using an old Technics SU-8099 amp to supply the Klipsch Cornwall bass bins with 115 watts each. However, I will be upgrading this amp to 2 Crown CD300A monoblock amps which will provide 350 watts each to the Cornwalls.

I DO have a few questions....

1) Since I'll be crossing the 902s anywhere between 600-800Hz at -24dB per octave, will I be pretty much safe by removing the loading caps? (I only reach PEAKS of about 105dB on occations, but not often)

2) Do any of you have your speakers actively crossed over? If so, what is your choice of crossover and why?

3) Really doesn't have much to do with the crossover, but what do you all do to try and "brighten up" your 902/511B topend?

I know some of you have mentioned opening up the drivers and looking at the diaphram to see if it's aluminum or etc, etc. If I think about it and have the time, I'll pull them open and take a peek inside.

But if they are aluminum (which I really think they are) what can be done to open them up more? I do not want to use a tweeter again, and would possibly like to get away from tone controls and EQs if possible, but that may be asking for too much.

Anyway, if you all could chew on this for a while and come up with a few good answers, ideas, comments, etc, etc, I'd certainly appreciate it.

Thanks in advance!
Charles

[Art J.]

Hello Charles, congrats on the active set up. You will enjoy it very much.
I would recommend that you save your loading cap ideas for very last, after
you are all set up and comfortable with your new system.

You may notice an improved top end just by the elimination of old passive components.
During the initial set up and experimenting, you may get some nasty transient spikes
specially if you loose power to the active crossover. The loading cap and low volume
will protect you from a shattered element. Have fun and keep us posted on your progress.
More later. Art

[cclark65]

ok, I really don't know how picky you are about electronics, but I had one of those crossovers for my bigger PA once, and used it for about 30 minutes and disconnected it and sold it. The output was way less than what my previous crossover was (peavey) and it didn't sound good at all I didn't think. I put the peavey back in and like it much better. (personal opinion)

I am running my PA 4way active. I have considered using an Altec 2way crossover for the mid/high part so I could use the modules for horn eq (I have MR horns). Maybe you should watch for an Altec or Electrovoice one on ebay, something like this one that completed a while back: http://cgi.ebay.com/Altec-Lansing-EV...QQcmdZViewItem

Keep in mind that you would need 2 of the 1631's for stereo use. I think the 1632 is a stereo crossover though, so if one of those comes up, you might want to check it out.

[Todd W. White]

The 1632A is a two-channel, two-crossover or a single-channel, three-way crossover.

It also has some brick wall limiting in it that I really liked - prevented customers from overdriving their amps and blowing up their speakers.

[chopsrr]

I've heard mixed reviews about Behringer products. I just figured I'd give them a try again since I had good luck with their AUTOCOM-PRO a few years back.

Well, are there any other crossovers out there that you all recommend? I'm looking at $150 or less for a crossover and -24dB Linkwitz. Maybe later on down the road, I'll upgrade to something better if need be.

I used to have a dbx Project 1 223 crossover which worked great, but it had a really nasty 60Hz buzz/hum that would not go away, which is why I bought the AUTOCOM-PRO.

I would love to get those Altec 1631s or 1632, but at $500 a pop, they're too rich for my blood right now.

Any suggestions?

Thanks again,
Charles

[Altec19]

Try searching the board for "electronic crossover". There has bee a great deal of discussion about this in the past. The Rane AC22/23 has often been suggested. Rane has an excellent library and FAQ section on their site that deals with more than just their products.

Link to Rane

[Russ Farrell]

Hi Charles:
My 1632 was about $30 on Ebay. Dip switches under a door on the top panel are used to set frequency. The plug-ins are for equalization to specific Altec systems. Not ideal for changing on the fly. But if you see one for $30,....

You've had plenty of responses to your 2 threads, but let me add my 2-cents worth. These are my preferences and personal opinions, not suggestions or rebuttals to other posts.

I'm a real fan of biamping. As to crossover frequencies and slope rates, each item in the speaker system including the room will affect "whats best". I often lean toward a little lower and slower, as long as its within the operating range of the components. For home, 24 dB hasn't worked for me, but 375 Hz at 6 dB/octave makes me nervous. The 511B horn doesn't present a decent acoustic load to the diaphragm much below 800 Hz. BTW I like loading caps off at your listening levels at 800 Hz and up.

Charles, I will make one strong recommendation. Especially when biamping, power the amplifiers LAST ON - FIRST OFF. Turn-on transient surges from any of the items before the power amplifier can ruin a diaphragm in an instant. And don't trust the power amplifier turn-on delay circuit. I did when I was in a hurry last year. Blew a 604-8H diaphragm, and my left ear.

I've known people who remove the bug screens, and others who said it didn't make a difference. I have a 902 that someone had pushed in the screen, so I removed it. I did a quick listen (years ago), and my impression was it was maybe a bit better than another one that had the screen. A very unscientific test and therefore not to be trusted. But if I were to use them I'd take out the other screen.

HF response: Your pink noise plot sure jogged my memory. As GM said it looks the same or better than curves run in the Anaheim acoustics lab. I remember the peaks at 16 kHz and 20.5 kHz very well. The general rolloff at the higher end is typical of HF compression drivers from any maker.

Audiotechniques marketed "Big Red" monitors to major recording studios. They were based on the Altec 604E coaxial speaker and the Mastering Labs crossover. The HF driver was essentially a 16-ohm 802. Audiotechniques looked at making a high-power speaker they called the "604-E2". During its development, on one of my visits, Rick Anderson, their speaker expert, asked me if I had heard any comments about the differences in sound and response between 8 and 16 ohm diaphragms. I personally hadn't, before or since. So Rick brought me into their assembly area and gave me a quick demo he had set up. To him, and to me, the 16-ohm sounded more "open" (I hate using such an unscientific term, but it's what came to mind at the time). The high end did seem a bit better on some music. Charles, please do NOT go out and buy 16-ohm diaphragms based on this. Only a controlled double-blind test of multiple drivers would show if there was any validity at all to this. Probably every person on this board would rather you spent any extra cash on some good Altec woofers. Maybe someone else on the board has tried such a test. I'm using 16's in my 604H's but at my age I couldn't hear the difference even if there is any.


Checking the polarity and phase of your system components is another subject that comes to mind. If you have any interest in my thoughts on it, let me know.

Russ

[cclark65]

yes, I have a couple of Rane AC22's that I plan to use when I bi-amp my monitors. I have used them for other things in the past, they sound very good.

You can find the 1631's and 2's on ebay for well under 100 bucks each if you just be patient

[chopsrr]

Originally posted by Charles Clark:
yes, I have a couple of Rane AC22's that I plan to use when I bi-amp my monitors. I have used them for other things in the past, they sound very good.

You can find the 1631's and 2's on ebay for well under 100 bucks each if you just be patient

<font size="2" face="Verdana, Helvetica, sans-serif">Yes, but don't those 1631's and 2's use plug-in modules for the crossover frequencies?

I'd rather have a crossover that I can tweak on the fly.

[chopsrr]

Hi Russ,

Thanks for your thoughts.

I think as far as a crossover is concerned, I want something that is NOT going to introduce noise into the system. Like I said before, I used to have a dbx crossover that had a 60Hz buzz all the time. No matter what I did, I could not get rid of that buzz. I was forced to buy a noise gate to take care of the problem. This is something I do not want to go through again.

If I can, I'd like to be able to get my hands on a crossover that can possibly go all the way up to -48dB per octave, just so I can cover all my bases and not wonder "What if?".

I don't have to worry about power turn on/off. My Panamax and Monster Power units both do this automatically. I have yet to have a single problem with turn on/off pops.

I'm not going to bother with the bug screens. I just don't see how these would effect the sound that much. However, once I get the crossover and amps all set up and running, then maybe I'll consider removing the loading caps. We'll see.