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4343mod
09-09-2008, 12:07 AM
Hey all,
Just wondering if anyone else gutted the passive crossovers out of their cabs and went active. The whole HTPC thing has gone far what with multi-channel sound cards that offer configurable 6+ channel out (Lynx, RME, others?) and the few tweakers on DIY Audio that have developed hardware-based crossovers...Me, I'm just a mere mortal and use Behringer DCX2496 boxes.

You are not stuck with those old dried caps and saturation-prone chokes, you know!

I have been all over this in other threads of the past, now I'd like to hear what you have done to get some new with the glorious old. Go Vintage JBL!

Maron Horonzakz
09-09-2008, 07:48 AM
Been doing three way active for thirty years,,, :applaud:

RKLee
09-09-2008, 09:04 AM
I have been doing it since 1975. The sound from an active crossover speaker is so much clearer, to me it is well worth the trouble. I am using 2 Altec 414 woofers for the bass, Altec 806/811 for the mids, and EV T350 super tweeter per cabinet, I am using an ancient DeCoursey crossover with plug in cards at 800Hz and 7kHz with 12dB/octave Butterworth. In restropect, I should've use 18db/octave.

louped garouv
09-09-2008, 09:30 AM
i am cobbling together another all active system...


subwoofers are two dual 8" EAW boxes per side
(they are EAW SB-48s)
woofers are Altec 406As with passive radiators in a Bolero Box
upper mids are Altec 802-8G on McCauley lens horns
tweeters are JBL 076 and 075

Here's the configuration for the crossover i am going to use...
it's a vintage model EQR5 from a company called
Sound Environments in NJ, i figure circa mid to late 70s vintage




Input Section is:
20Hz HP @ 18db/OCT to Sub-Bass
20Hz HP @ 12db/OCT to Full Range


Output sections are:
Sub-Bass; 106Hz LP @ 18db/OCT - Normal
+4.5db Boost @ 43Hz w rapid cutoff below - EQ Active
Front Panel Control: Unity Gain @ 12 O'Clock. +10db at full CW rotation. Full off at CCW.

Full Range 3-way Section
Low; 1,200Hz LP @ 12db/OCT (derived from subtracting HP from FR)
+6.5db Boost @ 65Hz w rapid cutoff below - EQ Active
Mid-High; 1,200Hz HP @ 12db/OCT (no upper cut off)
High; 6,500Hz HP @ 12db/OCT (no upper cut off)
Front Panel Control: Unity Gain @ at full CW rotation. Full off at CCW.

Tweeters; 7,000Hz HP @ 18db/OCT (no upper cut off)
Front Panel Control: Unity Gain @ 12 O'Clock. +10db at full CW rotation. Full off at CCW.


Hope this was helpful to you. My engineering opinion is that 12db/OCT in the mid band is the best slope for minimal phase aberration in an analog crossover. All filters are Butterworth except my active EQ's which are an elliptical filter of my design. I will try to find a performance graph and scan it for you soon. We can modify your unit to any cross points desired depending on your system requirements.

rj2077
09-09-2008, 09:43 AM
i just bought a THRESHOLD PCX unit. it is set at 18 db/oct from the factory. it comes w/ many x-over points. most importantly it came with 200hz, 250hz, 294hz cards/chips that will suit the jbl's that i have. i got it yesterday, so i have not listened to it yet. i am excited about its purchase. i WILL plug it in today...

regards

Mr. Widget
09-09-2008, 04:26 PM
I am using 2 Altec 414 woofers for the bass, Altec 806/811 for the mids, and EV T350 super tweeter per cabinet, I am using an ancient DeCoursey crossover with plug in cards at 800Hz and 7kHz with 12dB/octave Butterworth. In restropect, I should've use 18db/octave.That sounds like about the best Altec system I've heard of on the forum. As an upgrade, I'd go with the 511 horn and keep the crossover frequencies the same. Well done!


Widget

4343mod
09-09-2008, 06:05 PM
All sounds like exciting gear, men...
Have those of you with vintage active X/O's retrofitted the caps or anything else?
What are you all doing for amplifiers?

(Crown studio reference 1 on the bass and Rane MA 6 on the MF, HF & UHF here)

Doc Mark
09-09-2008, 06:07 PM
That sounds like about the best Altec system I've heard of on the forum. As an upgrade, I'd go with the 511 horn and keep the crossover frequencies the same. Well done!


Widget

Hello, Mr. Widget,

As I have a pair of each, 811 and 511, I've always wondered what the big difference between them is, besides the fact that one can supposedly be crossed over lower? In most of my older Altec information, Altec actually crossed over both of these horns at around 1200 HZ. Thanks, very much, for any thoughts, or comments on the performance of these two horns. I'm thinking about getting rid of one pair, and keeping one, "for a rainy day", and need to decide whether it's the 811's, or the 511's, that will hit the bricks..... or, should I just keep both of them, just for grins??!! ;):D Take care, and God Bless!

Every Good Wish,
Doc

JBL Dog
09-09-2008, 09:36 PM
Hey all,
Just wondering if anyone else gutted the passive crossovers out of their cabs and went active. The whole HTPC thing has gone far what with multi-channel sound cards that offer configurable 6+ channel out (Lynx, RME, others?) and the few tweakers on DIY Audio that have developed hardware-based crossovers...Me, I'm just a mere mortal and use Behringer DCX2496 boxes.

You are not stuck with those old dried caps and saturation-prone chokes, you know!

I have been all over this in other threads of the past, now I'd like to hear what you have done to get some new with the glorious old. Go Vintage JBL!

I'm using a JBL 5234A active crossover with factory 4343 cards for my 4343's. I guess you could call that 1/2 active, 1/2 passive since I'm still using the internal passive crossover for the mid, HF and UHF drivers. I don't think going 4-way active is anything I'm going to consider in the future.

rj2077
09-10-2008, 09:14 AM
i plugged in the threshold PCX last night.............men, what a difference. i HAVE NEVER heard the old 4343's sound THIS GOOD!!!!!!!! i can not begin to explain what a positive difference it made, top to bottom. the chips that i used are set at a x-over point of 296hz. i highly recommend using an external x-over..

regards

yggdrasil
09-11-2008, 12:57 AM
A while back I installed an active 2-way crossover in my 4-ways. At the same time I removed all unneccesary passive circuitry.

On these speakers there are no way back.

The crossover is DIY. 250Hz, 24dB/octave Sallen-Key.

mvaldes
09-11-2008, 03:01 AM
i plugged in the threshold PCX last night.............men, what a difference. i HAVE NEVER heard the old 4343's sound THIS GOOD!!!!!!!! i can not begin to explain what a positive difference it made, top to bottom. the chips that i used are set at a x-over point of 296hz. i highly recommend using an external x-over..

regards

:applaud:

that should be the one I was watching on Audiogon.
I wasn't shure to buy it because the 18db slopes doesn't fit with my 4430.....
Anyway this xo should be really great.
It's a totally classA discrete opamp, and it is a Nelson Pass project
I have the schematics of it, and I'm trying to figure out if it is possible to change the hipass to 6db instead of 18db
Any help will be very welcome

Michele

Valentin
09-11-2008, 04:11 PM
i am using DEQX active 3 way with lexicon 412 (bryston 8B) Amps
with LSR 6332 monitors and the sound is spectacular no way back.
i alsow have the active LSR subs but havent integrated to the system.

macaroonie
09-11-2008, 04:35 PM
If you have not seen this it is a start to finish build 300 ish project but fully active.

http://audioheritage.org/vbulletin/showthread.php?t=17238&highlight=backyard+box&page=8

discus96
10-22-2008, 09:27 AM
I have been thinking of going to a four way active xover system for a while now.

My project is to build and test an active four way JBL 4350 and compare it with my standard JBl 4350 with its original passive 3107 xover.

I have all the components 2235H, 2202H, 2441 and 2405H and intend to use two Behringer DCX 24/96 as active x-overs.
The Behringers should be able to time align the different drivers take care of the phase shifting, provide the right xover frequencies and slopes plus equalizing if needed.
I will use four amps with independent level controls also for additional flexibility.
Testing could be accomplished by the Behringer DEQ 2496 and its RTA with dedicated microphone.

Any suggestion? Is it a crazy trial or you think that would bring a benefit from cutting out the the old jbl 3107 crossover?

4313B
10-22-2008, 09:47 AM
I have all the components 2235H, 2202H, 2441 and 2405H and intend to use two Behringer DCX 24/96 as active x-overs.Isn't there anything better out there? That's kind of like shoving a Ford Pinto motor into a Maserati isn't it?

Any suggestion? Is it a crazy trial or you think that would bring a benefit from cutting out the the old jbl 3107 crossover?Those components are 4355 components. Use a cc 3155 network.

Serum
10-22-2008, 11:18 AM
xilica has an xo with brick wall FIR filters, they cost around 2000 euro here, it's by far the cheapest linear phase cross-over i could find.

Still debating whether to pick the one with or without this feature. (their non brick wall version is 1/3rd that price and seems to be pretty good too)

1audiohack
10-22-2008, 08:03 PM
I have used active crossovers in my system for 15+ years beginning with my attempt to build the "Ancient Audiophiles Quest for the Ultimate System" as found in the Perspectives page on this site. A good fun read for anyone who hasn't yet found it.

I used a Furman Sound 4 way with big Adcoms on the 18's and 15's and a Rane MA-6 for mids and highs. Fun!

Next came a Rane AC 23 with delays! Big help. A JBL m552 split the bottom.

Then a DBX Drive rack. Its now in the garage system.

Now it is 5 way active with a DBX260 on each side. I am quite happy with them.

Even then, its tough enough with a TEF unit, LinearX CrossoverShop and a decent pair of ears, I seriously don't know how the folks in passive land get it done! My hats off to them!!!

pos
09-03-2012, 02:53 PM
xilica has an xo with brick wall FIR filters, they cost around 2000 euro here, it's by far the cheapest linear phase cross-over i could find.

Still debating whether to pick the one with or without this feature. (their non brick wall version is 1/3rd that price and seems to be pretty good too)
The xilica is too limited with its power for usable 96khz FIR crossovers.
The software does not tell the truth about the slopes you get at the end, and the unit clearly does not have enough taps for even 3-way speakers (let alone 4-way).
You can share the total 1600 taps among channels, but as the unit only allows for brickwall filters (ie the shape and slope is commended by the number of taps and the frequency) you absolutely need to have the same number of taps each side of a crossover point to get matching slopes (and canceling ringing).

A better unit is the Ev DX46.
It only has 6 channels but 512 taps per channel (and in 48khz...).
It also only have brickwall filters, but much more usable, and it is cheaper to boot!
This is the unit I am currently using.

Another alternative to obtain linear phase filters (and systems) is to correct the phase of a existing IIR filter (such as the DCX).
I recently started developing a software that does just that:

http://sourceforge.net/projects/rephase/

It is still in beta but a new version is coming along.
It produces a phase-correction impulse (and also phase-linear magnitude corrections and filters of arbitrary slopes, but that is not its main purpose) that you can then use with a convolution software (such as foobar2000 convolver or VST convolver which are both free) or hardware (like the minidsp openDRC) inline with your DCX2496 or any other IIR digital or analog crossover (or even with passive speakers).

Serum
09-03-2012, 03:28 PM
have you ever tried the le 'cleach theory on your filters? I'll have a look at the software!

pos
09-03-2012, 03:35 PM
I don't use Le Cleac'h filters. Trying to align the impulses of drivers that are shifted by phase-minimal filters does not look really sound to me.
If I have to use minimal-phase (IIR) filters I prefer Linkwitz-Riley types (with EQ to obtain real L-R acoustic slopes), and live with the phase shifts...
(or correct them using rephase :D)

victoriobenatti
09-13-2012, 04:11 AM
In my system, the cut-off points of 4-way active crossover Techvox TPX2341SM:

Subwoofer: 20-63 hz (mono)
Woofer: 63-190 hz (Not exactly the same on both channels)
Mid: 190-1100 hz (Not exactly the same on both channels)
Treble: 1100-20000 hz (Not exactly the same on both channels)

Subwoofer: Dahlquist DQ-1W (with SS)
Woofers: D123 (with SE-KT88)
Mid: D123 (with SE-2A3)
High: 2420/811B (with Pure Triode)

11 years I use the active crossover.

Victório Benatti