Active vs Passive Xover Qs (Not certain where to post)

[nola]

Hello:

Not certain if this is the correct Forum for this post. Considering buying active crossovers to save building lots of passive xovers to test out the items below and to test out different xover points easily.

I have mid - late 1970s Khorns and LaScalas. I have AA networks with Crites Sonicaps. I also have 1 set of homemade ALK Universals, bought as a kit from Mr K in 2009.

To test out: I have 1 set of wooden horns, bought 2nd hand in ?2009-2010, 1" throat , driven by typical Klipsch mid range drivers, same as attached to the stock K400 squawkers. When I tested these out back in 2010, I noted different tonal qualities vs the stock metal horns, but I could not say 1 was truly better than the other. (My hearing, my room, my rig). My goal - reproduce the original live sound, LOL. I could never figure out which was closer to what I thought the live performance would have been like. Living in New Orleans I can listen to the real deal all the time, so I spend very little time on my main room system now.

I have 1 set of Altec 511Bs with Altec 902-8T drivers. I am aware that the xover point for the K33 in the KH should be 350-400ish HZ, maybe a bit higher for the LS at 400+ish Hz. Altecs like to be over 500 HZ. So yup, we may have a problem here.

I have 3 MR94B Altec MantaRays with 3 Altec 291 drivers - but at 16, not 8 ohms. Ditto for the xover point from the K33 woofer driver.

I may buy replacement tweeters, eg Beyma CP25s as well, due to blown LaScala tweeter (vs new diapragms).

In trying to figure out whether to try 2 way (no separate tweeter) vs 3 way setups (with separate tweeter) with the Altecs, might it be worthwhile to get an Active crossover? In the past the Electrovoice EV DX38 seemed popular, but it is no longer made. They also sold for about $1000.00 new, often over $500 used. dbx, Rane, and Behringer also have similar sounding products listed at websites like Musiciansfriend, Sweetwater, Guitarcenter, etc. I would prefer not to spend $1k on an active xover. Many of the other brands have devices in the $100-400 range, There was a also a post on the MiniDSP, at lower cost. Marchand Electronics and Elliott Sound (http://sound.westhost.com/project09.htm) also have devices.

I have lots of amps, so even triamping would not be an issue for me.

If I mess with something to replace the K77s, like the Beymas or Crites CP125, Fostex, etc, but keep the K400s or use the wooden horns (but not the Altecs) should I alter my existing xovers somehow? I know Bob Crites has the A 4500 - so long as the K77 is replaced. Maybe the ALK Uni's or existing AAs could be "adjusted" too, perhaps by swapping a capacitor or 2, moving a transformer tap, etc, to save the cost buying 2 new xovers. Or would having a good quality active or digital xover be the simple and easy answer for my "experiments"? If so, which one should I get?

Advice appreciated.

From NOLA with love.

[Don Richard]

For experimentation like you want to do digital active crossovers are hard to beat. In addition to the crossover function there are parametric EQs, delays, and limiting available. If you like to tweak things you will be in hog heaven with an active setup. Get a 3 way unit and if you want to go 2 way with it that can be easily done also.

If you have never used an electronic crossover before put some blocking caps in series with the midranges and tweeters so that any accidental errors in the settings won't damage the drivers. It is also mandatory to have a way to take measurements so that you can see the effect of the changes that you made. Setting up an active system is a fairly complex endeavor, not plug and play at all. Have fun and good luck.

[ZAKO]

Ive been useing active xovers for over 40 years,,,NEVER turned back,,,Get yourselve a MARSHAND 3 way crossover,,,I find it better than the prosumer brands..

[nola]

Thanx folks. But which specific units to look at? Marchand is in the US. dbx, Rane, Behringer, etc are also represented in the US. Elliott Audio is in Ozzie. MiniDSP is in Hong Kong. ElectroVoice does not make the EV DX38 anymore. I have a mic from my Velodyne SMS 1. But I do not think it is calibrated, if that truly matters. For a calibrated mic, Parts Express had one below $50. (Years ago, I think I used some free test tone software and my Radio Shack SPL meter- RCAd into my laptop to test out the bedroom. I had some correction values for the SPL, mostly for low frequencies. I then used the limited equalizer on the Onkyo 805 to do some modest adjustments. In the end, I got some improvement and never used the SMS1 system again, as I thought it sucked out too much bass from my RSW 15.) Balanced USB hub will cost about $100 - someplace I read that this was needed as part of a ?MiniDSP set up. For the subs, both my Outlaw Audio 990 Preamp/Processor and Onkyo 805s can set a subwoofer cut off value (Hz) and my sub amps can do that too. So do I need to do this as part of my electronic / digital / active crossover? I think the miniDSP can also time align the woofer, mid and tweeter. I do not know if the other products can do that. However, I think both of my receivers can time align an entire speaker, per distance from the listener, though I doubt they can do the tweeter vs woofer, etc.

I do not know if I will end up with a 2 way or a 3 system, beyond the subs. So I will need to be able to at least test for 3 way.

I also read somewhere (sorry, forgot the links) that the impedance / voltage wanted by the MiniDSP might not match either the preamp output of a stereo receiver possibly not match that needed by an amp - SS or tube. So these, if true, would be major issues. I have 2 MC240 PP tube amps - but with different tubes in each, though they sound similar. I have an Outlaw Audio 750 SS amp. 5 channels. Also 3 different Adcom SS amps, all c. 1985, I think. So triamping is do-able, even if a bit of a pain, due to all things to turn on and off, esp if a sequence is needed.

Others have also mentioned the need to protect the tweeter (more the mid range). What are blocking caps? Are they like the Zener diode on the AA crossovers? Etc.

What do I use as the output source for the active crossover? Is it the L/R set of RCA plugs from the Tape out or VCR out portion of the processor / receiver? 990 has 8 xlr ouputs incl L and R.

[Don Richard]

I would not go with the Marchand crossover. It is an analog unit with no delays, non-adjustable slopes, not very flexible. Almost any digital processor these days is full featured with different types of filters, slopes, delays, EQs, etc. The MiniDSP are digital units that have the advantages of several I/O configurations and RCA inputs and outputs in addition to delays, and PEQs. Several people here are using the Behringer processor with good results. The EV DC One is still being manufactured and is used by some in place of the DX 38. One guy is using a Yamaha processor to triamp Khorns, so there are many choices that will work for what you want to do. I would suggest not going with the DBX Driverack PA, though the higher end Driveracks such as the 260 and 4800 are good (and expensive). Using the forum search function will bring up lots of old threads about this subject and may help you decide the best way to go for your situation.

[nola]

I will also re-post the original thread to the technical Q area, as that might be more appropriate. Apologies to the moderator if this was not the correct place to post these Qs.

[Islander]

I occasionally hear that the Dx38 is discontinued, but new units are still for sale from some dealers:

http://www.avshop.ca/sound-amp-pa-audio/signal-processors/system-processors/ev-dx38-two-in-four-out-loudspeaker-processor

Used Dx38s are also easy to find.

The DC-One is a fairly new model, also easy to order in Canada or America:

http://www.avshop.ca/sound-amp-pa-audio/signal-processors/system-processors/ev-dc-one-two-in-six-out-loudspeaker-processor

http://www.americanmusical.com/Item--i-ELE-DCONE-LIST

The DC-One and Dx46 are current models listed on the EV website: http://www.electrovoice.com/family.php?id=26

The DC-One was just released in 2008:

[Chris A]

I will also re-post the original thread to the technical Q area, as that might be more appropriate.

Here is the thread that Greg Oshiro posted a couple of years ago using the Yamaha SP2060 digital crossover. I, too, recommend the use of a digital crossover so that you can correct the rather terrible bass bin and midrange delays.

http://forums.klipsch.com/forums/p/156476/1651290.aspx

Note that Greg is in the business and knows his stuff, so I'd look to his thread first for ideas on how to do tri-amping, and even would recommend that you email him for specific guidance.

I'd recommend any of the digital active crossovers other than the DCX-2496 from Behringer - a few more bucks makes a world of difference in this area. Used EV DC-One crossovers may exist on ebay nowadays.

I actually don't recommend the Dx38, since it is only a 2-in, 4-out unit, and it sounds like you need a 2-in, 6-out unit.

If you go to Ashly, they have 2-in, 8-out units that can also integrate your subs into your stereo front channels, which you might like to try filling in below ~40 Hz.

Chris

[nola]

Thanks for the reccs. However, I am trying to keep costs way down. I have checked Ebay, etc from time to time as well.

I emailed Ron Elliott in Ozzie and he kindly wrote me back. However, I do not know how easily parameters can be changed with his products. MiniDSP in Hong Kong has not replied yet. Their products might be the most economical for me. I may need to call HK using Skype.....

[kg4guy]

Ashly Protea has my vote .

[jcmusic]

Hey Brian, I went through the exact same dilema you. I solved it by building the ultimate passive xover you are welcome to come by and hear for your self!!!

Jay