AnAnalogue active crossover for speaker project!

[dogscanskate]

I'm currently collecting the remaining parts for my speaker project (WD 25T, dynaco clones from world designs) and would like to drive them active.

I've all but eliminated digital crossovers as I still run a record player. I'm currently tempted by offerings by Marchand and would consider other options if they were worthwhile. I know of the old KlarK-Teknik (dn800 iirc) which is quite rare and the Bryston units too. I'm looking for a 2 way XO with 2KHz crossover frequency.

The XO has to have balanced inputs/outputs. I would also like notch filters if that makes any sense and possibly step baffle correction if needed.

The amps are ARC D-130 (sand amp) for the lows (sensitivity for full output=1.71 volts) and ARC VT-50 (tube amp) for the highs (sensitivity for full output=1.95 volts).

My budget hovers around 2K$ for the active XO and any recommendations are appreciated.

[Glowbug]

How about pro sound gear?

Rane and others make very competent analog Xovers...and balanced I/O would be no problem.

[dogscanskate]

I have no problems with pro sound gear !

[gfiandy]

Unless you have a reason for not going digital other than idealistic, I would use a ULTRADRIVE PRO DCX2496 from Behringer, you can get one of these for about $400. It uses some of the best DACs and ADCs available and has every concivable adjustment you could ever need. It has an ADC so will take your LP input and convert it to digital.

Then spend the rest of your $1500 on a decent measurement microphone, a preamp and a good speaker meausrement program - CLIOWIN would be a good option. You could also get a speaker simulation package there are some free ones such as speaker workshop or you could buy LEAP which is the industry standard (They are all difficult to use, but leap is a bit less difficult than Speaker workshop). You may get away with not buing a simulator as with the berhinger xover you can make changes so quickly you could work in the "real world".

I belive you will get a better result this way as a very significant part of a speakers sound is the quality of the alignment you achieve. It is very unlikley that a generic PA crossover will work without measurement and even then it may be very difficult to get the drivers to intergrate as you often need to include the acoustic roll of in with the crossover roll off (i.e the two electronic slopes are not the same).

If you must go analogue, I had a look at the Manchard crossovers and only the top of the range one alows you to have different slopes on the LP and HP sections, I consider this essential for a HiFi speaker set up unless your region of overlap is massive (Which is unlikely in a two way design). It has to be configured by swaping out the resistors which will take alot of time. You will still need a measuremnt system to get it right.

Alternatively a possible brute force method might work if you went for the 48dB per octave filter Manchard make. This might be fast enough that the region of phase problems would be sufficiently small that it wouldn't upset the sound much. I have never tried this approach so can't say for sure. Maybe someone else who has coulds chip in here with a opinion :-). Opinion on very steep filters is split many people don't like then some rave about them.

Sounds like a fantastic project though and I envy you your budget!

Regards,
Andrew

[Cokewithlime]

Originally Posted by gfiandy

Unless you have a reason for not going digital other than idealistic, I would use a ULTRADRIVE PRO DCX2496 from Behringer, you can get one of these for about $400. It uses some of the best DACs and ADCs available and has every concivable adjustment you could ever need. It has an ADC so will take your LP input and convert it to digital.

The above is an excellent suggestion, if you are looking for the ultimate in control I would suggest adding to this the Behringer ULTRACURVE PRO DEQ2496 as well which will provide you will real time analysis and eq correction capability and still be well within your budget

[pk]

I would seriously consider the DCN23 kit from Ground Sound

See:

Ground Sound

The DCN23 is a digital crossover with a lot of very user freindly features. For instance you can change crossover configurations "on the fly", that is, while the system is 'on', which I find very convenient! The excellent software also allows to incorporate driver measurements directly as a basis for the filter configuration.

It is well within your budget. It is more expensive than the Behringer, but it also easier to implement, and I would asume that the sound quality is better too....

Best regards
Peter

[planet10]

If you get a DCX2496 make sure that you leave budget for modifying it... when used with analog in, the one i had did not sound very good at all.

For maximum analog goodness, a buffered version of the passive line level XO from Marchand might be worth asking after,

And since you are doing the WD set, let me point out the Classic TL for these drivers at the bottom of this page:

Transmission Line Speakers

dave

[holdent]

I have a Behringer CX3400, an analogue active xover which has balanced inputs and outputs. Its easy to use but you're stuck with 4th order (24 dB) Linkwitz-Riley filters. However it doesn't have provision for notch filters or baffle step correction. I considered the Marchand route but it was way out of my price league and you're still stuck with LR filters that have fixed filter slopes (in Marchand's case either 24dB or 48dB per octave).

To get the kind or flexibility you seem to be looking for you have to go digital. I thought about buying the DCX2496 at the time but had a really difficult time getting my head around what the system would look like. With the CX3400 (or other analogue xovers), the xover is between the preamp and the power amps. With the digital DCX2496 I think you have to have a multichannel volume control after the xover and then some type of input selector (in your case with a LP input) ahead of the DCX2496. For me this additional cost (and complication) scared me away.

[dogscanskate]

Thanks for all comments guys, I really appreciate it. Basically, I want to stress flexibility is not all that important. I may not need step baffle correction. As far as notch filtering is concerned, what has me interested in it is the possibility of emulating the BBC dip in the 4KHz region (as per Fletcher/Munson research for Bell Labs) and simply controlling the possibilities of the hump in the mid bass region (80-160 Hz). If a notch filter can't accomplish any of these functions, then I don't think I'd need it. Particularly in the treble frequencies, I can see the advantage of such a filter to tame not only the tweeters but also the different presentation of tube/sand amps. If that makes sense.

I still want to keep it simple and once "honed in" leave the controls alone.

The scary part with digital XO's is how an analog input that is transformed into the digital domain and then reconverted back to analog may create more problems and losses than a basic analog XO. I'm afraid that all the micro details could be lost in the transformations of the original signal. I'm really looking for transparency over flexibility.

[Charles Darwin]

I use a couple of BSS FDS360s.
With those it is possible to use all sorts of different slopes, including asymetrical and overlapping ones, there is also provision for shelving or parametric eqs.
The problem is that they are only available s/h and the original TL072 op amps should be replaced by something better. I use BB 2134s with great success although there are better (and more pricey) alternatives these days.

The thing that scares me away from Behringer products is that they are almost invariably badly built cheap rubbish and no professional would be satisfied with the sound quality.