Active crossover digital or analog

[davidpou]

Recent buyer of 4430 I am up for starting the bi amp trip. I was thincking about active crossovers: I used to own a driverack PA to do 2.1 with a small tube amp and an active sub, and I realised that the driverack was twisting the place of intruments as compared with the CD player directly on the (integrated amp). The sound was more say digital less dynamic. I eventulally sold the driverack after few weeks. I blamed the double conversion AN and then again NA as not doing anygood to the signal...my source is also the turntable and same story i would like to avoid any conversion....

Now, my preamp is a mcintosh C22 fed with telefunken and I do not want its output to be converted an reconverted.... or rather i am willing to avoid that.
So I thought to buy an analog active crossover like the dBx 234 xS but I see the slope is limited to 24dB /0 when the 4430 need 12dB/0...
How important is the slope respect ?

How good is the analog filter dBx 234xS ? do you have an alternative ? with the choice in slope ?

Other wise I could buy another preamp and put the 2496 after the CD player in AESBU... the bass amp will be either a phase linear 400 or a yamaha 2500s I haven't decided yet....

thanks for advice

[martin2395]

I also used to have a Driverack but I had the PA2 which I retourned within a few weeks. I didn't find it digital sounding at all, it was rather dark and uninvolving.

The 223/224 may be good but in modified form, don't expect too much from a stock unitas it's just a 'plain' unexpensive unit.
In my opinion if you want a really good xover - Marchand, Pass, BSS, Bryston or Klark Teknik are your best bet.

When I ran my 4343 with 24dB slope instead of 12dB I noticed a hole in the frequency between the woofer and the midwoofer so I'd expect the same with the 4430, the 12dB just gives a smoother transistion from one driver to another. In my experience 24dB sounded tigther but 12dB produced a more coherent image.

p.s
Watch out with that Phase Linear, if it's not recapped and has added speaker protection it's dangerous for your woofers.

[speakerdave]

Based on my reading of earlier threads on this subject I would suggest you do some reading about previous explorations of this idea. It's a little bit of a can of worms because of the special response shaping for that horn. More than one experimenter has in the end happily gone back to the internal crossover. I gather a primary goal is to be able to use a tube amp for the treble to improve the sound you are getting in that range. There is a thread at audio karma by someone who modified his 4430's to make them biwireable (Google < biamp 4430>).

There are some issues that would mask the benefit of using a tube amp:
--A basic first step would be to freshen--and/or dampen--the diaphragm if that has not been done.
--And consider biasing the network.

Alternatively (or in addition) there is at least one thread in these forums about using a TAD 2001--for the glories of Be-- in place of the stock driver, with network modifications.

The internal/external switch on the speaker assumes the use of the JBL/UREI 5235 with the special personality card for the 4430.

[davidpou]

Based on my reading of earlier threads on this subject I would suggest you do some reading about previous explorations of this idea. It's a little bit of a can of worms because of the special response shaping for that horn. More than one experimenter has in the end happily gone back to the internal crossover. I gather a primary goal is to be able to use a tube amp for the treble to improve the sound you are getting in that range. There is a thread at audio karma by someone who modified his 4430's to make them biwireable (Google < biamp 4430>).

There are some issues that would mask the benefit of using a tube amp:
--A basic first step would be to freshen--and/or dampen--the diaphragm if that has not been done.
--And consider biasing the network.

Alternatively (or in addition) there is at least one thread in these forums about using a TAD 2001--for the glories of Be-- in place of the stock driver, with network modifications.

The internal/external switch on the speaker assumes the use of the JBL/UREI 5235 with the special personality card for the 4430.

Thanks for all this.
Yes I am doing intensive reading (I spent the we over it) and I am at the confused stage.
I still cannot do a synthesis...

here in France, on our modest JBL dedicated web sites and on other forums, every one seems unanimous over the bi amping...as being better than mono
I found a theoretical blog over bi amp demonstrating its benefits in general case... I saw the audiokarma post on the 4430 crossover modification for bi amping and keeping the passive filter (one of the thing i certainly have to come back to);

yes the 2225H will be driven by a MC 275 (note exactlty 75W required for this driver!), so tubes , yes.
I will have a look at the diaphrams but i thought originals are better than aftermarket ?.... how do you threshen them up ? alcohol ?
what do you mean by biasing the network ?

Yes I have come across this 5235 with the card... I even found the link to a company doing replicate of this card ...
is the 5235 the ultimate solution ? would I be able to use a different filter if I am to just turn to the external switch? or would I have to bypass completely the passive filter and go dirrect to the driver and 2235H ?
are they analog active filters with a 12dB slope ?

Indeed the crossover point treatment is key... so slope matters... so the filter does...

I saw the post of a French guy from paris adding a 2123H to his 4430 for dealing with 300 -800 Hz (if my memory is correct)....I saw some "homemade" FR curved quite frightening with a big - 6dB at 1k€ on the 4430....
sorry it s a lot of questions in one post

[davidpou]

I also used to have a Driverack but I had the PA2 which I retourned within a few weeks. I didn't find it digital sounding at all, it was rather dark and uninvolving.

The 223/224 may be good but in modified form, don't expect too much from a stock unitas it's just a 'plain' unexpensive unit.
In my opinion if you want a really good xover - Marchand, Pass, BSS, Bryston or Klark Teknik are your best bet.

When I ran my 4343 with 24dB slope instead of 12dB I noticed a hole in the frequency between the woofer and the midwoofer so I'd expect the same with the 4430, the 12dB just gives a smoother transistion from one driver to another. In my experience 24dB sounded tigther but 12dB produced a more coherent image.

p.s
Watch out with that Phase Linear, if it's not recapped and has added speaker protection it's dangerous for your woofers.

Thanks,
I will give a good look a these other brands.
This hole is what i would like to avoid or minimise... so the idea of adding a 2123H or a TAD 2001 are to be studied....yes i got confused about the slope discussion but i keep in mind that i have to stick to the passive filter characteritics, if possible...

Thanks very much I heard the danger of the phase.... apparently we have a specialist in the south of france who add the extra fuse or protection required... the issue with the phase: its vintage so will need a check up, it cost two times the price of the yamaha, and it doesn t come with waranty.....

[speakerdave]

Thanks for all this.
Yes I am doing intensive reading (I spent the we over it) and I am at the confused stage.
I still cannot do a synthesis...

here in France, on our modest JBL dedicated web sites and on other forums, every one seems unanimous over the bi amping...as being better than mono
I found a theoretical blog over bi amp demonstrating its benefits in general case... I saw the audiokarma post on the 4430 crossover modification for bi amping and keeping the passive filter (one of the thing i certainly have to come back to);

yes the 2225H will be driven by a MC 275 (note exactlty 75W required for this driver!), so tubes , yes.
I will have a look at the diaphrams but i thought originals are better than aftermarket ?.... how do you threshen them up ? alcohol ?
what do you mean by biasing the network ?

Yes I have come across this 5235 with the card... I even found the link to a company doing replicate of this card ...
is the 5235 the ultimate solution ? would I be able to use a different filter if I am to just turn to the external switch? or would I have to bypass completely the passive filter and go dirrect to the driver and 2235H ?
are they analog active filters with a 12dB slope ?

Indeed the crossover point treatment is key... so slope matters... so the filter does...

I saw the post of a French guy from paris adding a 2123H to his 4430 for dealing with 300 -800 Hz (if my memory is correct)....I saw some "homemade" FR curved quite frightening with a big - 6dB at 1k€ on the 4430....
sorry it s a lot of questions in one post

By "freshen" I meant replace with a factory-new one-- not aftermarket!--either the titanium 2425 or aluminum 2421. For more recent drivers JBL has been using a dampening coat of aquaplas on the diaphragms and some forumites here have experimented with retro coating theirs.

I mention the 5235 because it provides response compensation needed in addition to what remains in the internal circuit with the switch on the External position. It would certainly be better as regards frequency response than any off-the-shelf crossover. Whether its sound is the ultimate would be more subjective, I think.

The I-E switch of the 4430 leaves only part of the passive network in the circuit.

To understand biasing the crossover do searches here for <charge-coupling>.

Biamping per se certainly offers some advantages such as connecting the woofer directly to an amp with no intervening low-pass inductor, and enabling the use of different amps for the bass and treble. However, implementation is seldom straightforward. If the internal crossover is taken out of the circuit the frequency response compensation that is probably universally included in it these days must be provided in some other way.

A three-way with woofer, cone midrange and horn tweeter is definitely a viable option, but if original the crossover network then becomes the poser. One of our members, Ian MacKenzie, has built one using the 2245, 2122 and 2344/2425. He might have some suggestions.

[Mctwins]

Hallo!

I have dbx PA+ and dbx260 and it is a great unit both of them. dbx260 is better, of course. I don't find the digital vs analog to be dull or dark at all. I had dbx 223XL and when I connected the PA+, it sounded better.

I would go for digtial.

[Mctwins]

I also used to have a Driverack but I had the PA2 which I retourned within a few weeks. I didn't find it digital sounding at all, it was rather dark and uninvolving.

The 223/224 may be good but in modified form, don't expect too much from a stock unitas it's just a 'plain' unexpensive unit.
In my opinion if you want a really good xover - Marchand, Pass, BSS, Bryston or Klark Teknik are your best bet.

When I ran my 4343 with 24dB slope instead of 12dB I noticed a hole in the frequency between the woofer and the midwoofer so I'd expect the same with the 4430, the 12dB just gives a smoother transistion from one driver to another. In my experience 24dB sounded tigther but 12dB produced a more coherent image.

p.s
Watch out with that Phase Linear, if it's not recapped and has added speaker protection it's dangerous for your woofers.

Hallo!

How did you manage to get it so dark and uninvovling? Please explain?

[martin2395]

I connected it, set it up and boom it sounded just like I described in my previous post. No idea why :o:
No idea what's wrong with it but in my setup is sounds just far from neutral. I like my recapped analogue BSS FDS-360 much more.

The 5235 is also very dated, it may have the required EQ options but again it will be limited by worn off and dated parts.

[Mctwins]

I connected it, set it up and boom it sounded just like I described in my previous post. No idea why :o:
No idea what's wrong with it but in my setup is sounds just far from neutral. I like my recapped analogue BSS FDS-360 much more.

The 5235 is also very dated, it may have the required EQ options but again it will be limited by worn off and dated parts.

Hmm...still don't understand what went wrong? Did you just connect it without any settings and called it a day.

There is a lot of factors that can get wrong.

[martin2395]

Of course I set it up before...300Hz xover, tested with either 12 and 24dB slopes. No additional EQ.
For my ears the DBX Driverack PA2 is just far from neutral sounding.

I will try the MiniDSP 4x10HD some day but now I have other expenses ;)

[Bobecca]

martin.....

Having the driverack sounding dull is not what I experience. My dbx260 is performing outstanding with my screen arrays and have been on for 24/7 since I got it for 4 years ago:D:applaud:

Very nice and realiable pieace of unit.

Something else has to be wrong in your setup with PA2.

Just saying.......

[martin2395]

There is nothing wrong with the setup, don't try to convince me what I heard. :D The DBX just didn't work out in my setup :applaud:

It's all in the match and I only described how the PA2 sounded for me as I'm used to the sound of my BSS FDS360 which sounds very airy, open en detailed.


I bought a Klark Teknik DN800 two days ago, it should arrive today (saturday).
Will report back when I get it reconfigured to 300Hz/12dB.

[allen mueller]

There is nothing wrong with the setup, don't try to convince me what I heard. :D The DBX just didn't work out in my setup :applaud:

It's all in the match and I only described how the PA2 sounded for me as I'm used to the sound of my BSS FDS360 which sounds very airy, open en detailed.



I'm in agreement with you're impressions of the DBX unit as well. I've had the PA and the 260 and I think you hear the same thing. To me DBX sounds a little congested and not as clear on the HF compared to the analog BSS and Marchand crossovers I've had. I'm currently using an Xilica DSP which I like and find very transparent in the setup when used.

Allen

[cooky1257]

Gain structure is important and particularly important when using a digital unit.
You must feed it hot enough to make full use of available bits but allow enough headroom-aim for -6dB peak on the inputs and be very careful of clipping individual channels post dsp-level(gain) and eq cuts are better than boosts to achieve the desired curve imo.

[martin2395]

Is it even possible to give it enough gain when it's used in home audio environment? Even with my KSA50mk2 poweramp + KRC-HR preamp I couldn't get pass the 2nd level LED on the PA2.

[cooky1257]

Is it even possible to give it enough gain when it's used in home audio environment? Even with my KSA50mk2 poweramp + KRC-HR preamp I couldn't get pass the 2nd level LED on the PA2.

Yes, I use a Benchmark dac2 into an XTA 224 LMS/DSP driving BBC QUAD 520f amps without any gain issues.

[Mctwins]

Is it even possible to give it enough gain when it's used in home audio environment? Even with my KSA50mk2 poweramp + KRC-HR preamp I couldn't get pass the 2nd level LED on the PA2.

Hallo!

If you only have 2nd level on LED bar, I asume you mean input, then you haven't done a proper Gain structure. If you don't understand this then you schoulden't complain about dbx Driverack having a dull sound.

Driverack isin't a plug and play device.

Before complaining, you have to provide how your set-up and connection is done. I belive you have done it all wrong and gave you that dull sound.

Your preamp KRC-HR has 14V (RMS) or 25 dBu, what's the fuzz about your 2nd level LEDon the PA2??

On the PA2 you have a button on the back where you can have either +4dBu or -10dBV.

Look and learn....;)


http://www.youtube.com/watch?v=rSv6nxw2T9M

[martin2395]

I don't have to learn about it anymore because I returned it already.
They assured me it was plug, simple config and play.

And again - I know what and how I configured it and the xover settings were 100% correct.
Havent touched any extra gain settings: http://nl.tinypic.com/r/167uqew/8

Even with my KRCHR switched to high gain and the driverack set on lower gain settings I couldn't go past the 2nd input led before ear deafening levels would occur. Of course I could lower the gain through the software but I didn't.

[frank23]

I use a 2123 with the 2420/2344 combination in a fuly active setup.

As an active crossover I have modified a JBL M553 to get rid of allmost all coupling capacitors inside. Only the input and output caps remain whereas the rest is now hard wired. I have run this configuration for about 2 years now I think and have not run into a problem, whereas the sound is much better than with the caps. Using a digital crossover is a no-go for me as I use a high end NOS dac and built in dacs of digital crossovers cannot give me the quality I want. In modified form the M553 has a respectable enough sound, and built in CD compensation.

But you have to study the 4430 passive crossover when you want to bi-amp with an active crossover because as far as I remember not all passive components are bypassed in active mode. I run my system fully active, apart from speaker wire there are no passive components between the amp outputs and the drivers. This can be done if the DC offset of the amps is low enough.