4 way crossover help

[aertex]

I have asked for comment relating to this area a while back and was rewarded with replies.

I am now a little further down the track of finalizing the electronics pieces to be set up in the system and feel the need to further clarify what options might be available to crossover frequencies.

I want to use the following set up:

transport into dac into active pre-amp into 4 channels of amplification into 4 drivers per side (actually 5, as I will run 2 bass drivers per side)

*Obviously some form of crossover needs to be inserted somewhere in that mix. I want the chosen dac to do the digital conversion and dont want another dac in the chain.

*I dont mind any form of active crossover as I want the benefits and flexibility of set up it offers to develop and tune the system(ie. slope adjustment, EQ, phase delay)

*I want to retain the transport in the chain at this stage, as opposed to a computer

*I am presuming a passive discrete type crossover would be too complex to contemplate at this stage, so am disregarding that option now-but would ultimately like to end up with a passive

In essence I am confused as to where an active crossover can slot in without stuffing up the digital conversion-as in introducing another conversion step. I really need to sort this one out before I pursue any sort of crossover. I have not bought anything and dont know which sort of crossover will do the job for me.

I hope those who read this get my (convoluted) drift on this one. If not I can try to provide a clearer picture

Alan

Edited July 9, 2011 by aertex

[THOMO]

Alan

You are welcome to borrow my DBX Driverack crossover.It is a three way.

I think you have heard it being used with my Edgar horn three way system.For experimentation/trialling some cheap T amps would do for amplification.

You might be best using a subwoofer plate amp for bass.These have inbuilt crossovers and usually some bass equalisation to give a flat response down lower.

[ArthurDent]

*Obviously some form of crossover needs to be inserted somewhere in that mix. I want the chosen dac to do the digital conversion and dont want another dac in the chain.

Which sort of rules out any form of DSP.

*I dont mind any form of active crossover as I want the benefits and flexibility of set up it offers to develop and tune the system(ie. slope adjustment, EQ, phase delay)

Do you have any idea how many bits this requires and the skill involved in not only designing it but building it.

*I am presuming a passive discrete type crossover would be too complex to contemplate at this stage, so am disregarding that option now-but would ultimately like to end up with a passive

Good luck with that one and why after you develop an active system with multiple amplifiers would you want to go back to a passive system.

My advise, having built multi way active systems for over 30 years. Buy yourself a couple of miniDSP units or one 2x8, use that to experiment with, ie work out all the crossover points, slopes, eq. etc. etc. and if you don't mind the sound of it when it's all up and running, keep it.

[Guest]

Hi Alan

If I were you I would go an see Pat @ WarAudio and see if he can build you something ,he is one of the best in the industrie's with passive & active xovers . Theres another option that you mighten of thought of .your transport into a DEQX with digital outs into your chosen dac's as outputs into your amps .I also wouldn't rule out your transport into a DEQX into your amps and hear what it sounds like when set up by someone that knows what there doing you will be suprised .Or you do what I'm doing building the xover into the gain stage's of you amps thens it front end,pre,power amps & then speakers .

Cheers

[Paul Spencer]

Firstly, it isn't the end of the world to have two digital conversions in a system. You can try a quick test with an existing system, simply add a switch box, loop cable and MiniDSP with no EQ or filters active. You switch from the loop cable to MiniDSP simply adding an ADA conversion. Can you even hear it? People make a big deal about it without ever having done this test.

I can suggest three ways to go about it:

1. Analogue xo

To do this one right, it may even work out more advanced and difficult than a passive crossover, which you are probably trying to avoid. Have a look at a Linkwitz analogue crossover to get an idea of the task at hand to do it right. It's not as simple as a few textbook filters. This is probably not an option for you.

2. Digital crossover where the xo unit adds another ADA conversion.

The easiest way to do it with the potential for very good results. Probably the best place to start as you can always upgrade to option 3

3. Digital crossover with only one DAC

In this case you feed a digital input into the DSP unit and you run a digital output. You then need a multi channel DAC and preamp, possibly built up of single units. This option is expensive. I suppose if you really were a purist you could use better DACs on the mid and treble, cheapies on the bass. You can buy a multi channel preamp for the purpose.

Or you just simply go for DEQX which does all this in one box and is also more powerful.

Starting out I would suggest with Ken to go option 2. MiniDSP does allow digital output, but at this early stage the real issue is your ability to design it.

[aertex]

Great stuff guys-thanks. Will absorb details later today and come back with a few more queries if thats ok

Thomo, thanks for your suggestion. May well take you up on it some time soonish. Sorry I missed those Tannoys! Would have liked to throw my ears at them in all there cabinet finery. Well done there

Kenny T. I think you misunderstood some of my convolution's there but I will clarify that later

Mal and Paul-interested to delve a little deeper here. As said I will seek further knowledge......when the grass is mowed and copius weeds sprayed. Love my acre block but gardening, or rather jungle undergrowth suppression is a *****!

cheers

Alan

[JA]

Hello Alan,

with the requirements and desires you've specified your solution is an analogue active 4-way crossover. Whilst analogue 4-way analogue crossovers exist, 3-way are far more commonplace. With some tinkering it is possible to use a 3-way analogue electronic crossover inconjunction typically with a simple passive crossover (for the UHF) either at line or speaker level to acheive a 4 way crossover. As to where the xover should go - In the set up you described and with your stated desires it should go between the preamp output and the respective power amplifier inputs.

Best

JA

[tuyen]

Hi Alan,

For 4-way electronic analogue crossover units: Pioneer D-23, GOTO CF-1 or EPH4001/4002, Accuphase F-25 and the Marchand XM44 or XM126 are the ones I can think of.

JA's advice re using a 3-way unit with the going a simple passive for the midhigh/high channels on the speaker line level (1 cap on high and 1 coil for midhigh, although will probably need to add a resistor to attenuate the mid-high a bit so it is balanced with the high) is a nice & simple possibility too..

[Nigel]

Alan, it seems you have a DAC that you like and don't want to use anything worse.

I think some of these digital crossovers have both types of output, so you can certainly use your better dac in the range that is most important and use the crossover's dacs for he other 2or 3 ranges.

Last year we compared the miniDSP dacs to some other dac and could not separate them, I was impressed with the quality of the dacs

in this $200 -$300 unit. (Not to mention it has EQ capability etc).

Just another route towards Nirvana......

[Paul Spencer]

Nigel, what did you compare them to?

[aertex]

Thanks again guys. Yes I have just bought a new dac that I selected carefully to best compliment the drivers I will use. Sadly the Zanden must be sold. Consequently I really do not want to dilute the chosen dac's signature with more digital sources-unless they are exceptionally good..maybe. I understand an active analogue is an option, though maybe its flexibility is limited (EQ, phase delay, slopes etc) -not entirely sure on that either. The marchand XM44 and XM126 may be most flexible but require purchase of new cards to make changes dont they? There could be numerous tweaks to get crossover right.

What sonic impact would a second digital crossover (like miniDSP) have on the first dac in DADA set up. Or, another way, which sonic signature (of which dac) would you expect to hear. Would the first (dedicated) dac be "heard"? The miniDSP does look interesting though

thanks, Alan

Edited July 12, 2011 by aertex

[gainphile]

The DACs will be transparent when speakers and room is put into perspective.

One thing with 4-way system is that the overlapping crossover slopes are not far enough to *not* influence each other.

For example, the Woofer-Midrange lowpass will influence Midrange-Tweeter highpass. This does not happen with 2-way nor typical 3-way.

Hence for a 4-way system, the stages must be cascaded. MiniDSP is able to do this

http://linkwitzlab.com/frontiers_5.htm#V

[Guest]

Hi Alan

Any updates on your xover .

CHeers

[Antripodean]

Alan, I would suggest the miniDSP 2x8 will do what you need with the digital in/out. Best ask on their forum. Like Nigel says, I am happy with the DACs in the unit but if you have a sonic preference for the DAC you just bought then best to do what you say.

[tuyen]

alan,

there is a mint cond. pioneer d-23 on ebay aus at the moment with your name on it

[tal]

Rather pricey though. Your could get two Behringer 2310's, one per channel, which are all analogue, for under $250 the pair, new. Only issue would be the sub-out - this isn't a proper 4th order LR electronic cross, it's a fill in for lower bass. Which means your midbass will go as low as it can, and you tune the HF cut on the sub to fill in where it rolls off. This might suit you, it might not.

[shaky]

Alan,

Just another idea for you to contemplate:

I'm in the midst of planning a 4 way active system and am going to use a car audio processor, an Audison Bit 1 I have. It is PC controllable, has analog inputs and 8 channel RCA outputs. Crossover slopes and frequencys are infinitely adjustable too. Also does Time Alignment. All you need is a 12VDC supply and you're laughing. I got mine from FHRX in NSW. Look them up if it interests you. Marty there is awesome to deal with.

Tim