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Thread: Active Crossovers

  1. #1
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    Active Crossovers

    Doing a search I couldn't see if this had been discussed recently, but are any of you using high quality active filters in your systems, and if so which?

    I've been looking at the likes of DEQX but would prefer to not subject my lovely forty year old vinyl collection to a rather crude A-D process unless someone is going to tell me it's transparent. I know Widget is using one. How is it and what's the rest of the setup?

    For analogue options, what's out there that's better than the Bryston 10b (which I thought sounded godawful)? Is there anyone out there making custom tube units that allow for baffle step and other variables? Also, when going active, are you leaving a passive cap in circuit to protect compression drivers from any unforeseen switch on thumps? Or running correction and attenuation filters passively as the DD66000 does when bi-amped?

    Sorry for all the questions but I just haven't been able to find anything that suits.

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    Senior Member louped garouv's Avatar
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    I use a RLA X2000 crossover from the Disco era w/ no caps for protection...



    I would bet if you wanted one badly enough,
    someone would build you almost whatever you could want....


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    Quote Originally Posted by merlin View Post
    Doing a search I couldn't see if this had been discussed recently, but are any of you using high quality active filters in your systems, and if so which?

    I've been looking at the likes of DEQX but would prefer to not subject my lovely forty year old vinyl collection to a rather crude A-D process unless someone is going to tell me it's transparent. I know Widget is using one. How is it and what's the rest of the setup?

    For analogue options, what's out there that's better than the Bryston 10b (which I thought sounded godawful)? Is there anyone out there making custom tube units that allow for baffle step and other variables? Also, when going active, are you leaving a passive cap in circuit to protect compression drivers from any unforeseen switch on thumps? Or running correction and attenuation filters passively as the DD66000 does when bi-amped?

    Sorry for all the questions but I just haven't been able to find anything that suits.
    I used a Yamaha D2040 pro unit. It has the dreaded a/d d/a process but I could not tell a difference. It is a $3,000 unit that I will be selling for $500 if you are interested. Google it. Very nice unit.

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    Senior Member Baron030's Avatar
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    Hi Merlin
    I canít answer all of your questions. But, I have tried several different compression driver protection methods. And using a passive cap in series with the driver is really a good idea, especially when it is your first time converting a system over to an active crossover. You will quickly learn that the amplifiers are last to be turned on and the first to be turned off, otherwise you are facing a really loud thump and some possible driver damage. For a long time, I was very skeptical about biasing and bypassing capacitors. But, now I am true believer. Going with biased caps will eliminate any notch distortion that caused by the protection caps. But, there is more one thing that I have seen discussed much around here. And that is the need for add damping resistors. When a cap is wired in series with the driver, then the driverís voice coil is no longer directly coupled to the amplifiers out. In the case of a passive crossover network, an L-Pad provides a lot of damping to the driver. But, in systems with active crossovers, the cap acts like a series resistor and the driverís damping suffers. For example, with a 2446H driver that was protected by a 545Hz 12db/octave high pass filter, I noticed a pretty dramatic improvement, when a 47 ohm Ė 12 watt resistor was wired in parallel with the voice coil. Actually, a good rule of thumb for a damping resistor value, would be to use a resistance that is 4 or 5 times the impedance of the driver.
    So, if you are going use a protection cap, seriously think about using biasing and bypassing the capacitors and add some damping resistance. Otherwise, just wire the drivers directly up to amplifiers and be very careful.
    Baron030

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    Senior Member HipoFutura's Avatar
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    I use an Ashly XR2001 to tri-amp my system. The Ashly x-over is fantastic. I did have a DBX x-over that was terrible. It was muddy on the sub/mid x-over point.

    The low-freqs and hi-freqs are split to SS amps and the mids run through tube mono-blocks. I love this setup and the Ashly x-over makes it all happen. Don

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    Hello Merlin

    In the active horn set-ups I have had, they both required a passive compensation circuit so there was a cap in series by default. In both cases I had the caps charge coupled. I was running aquaplased 2425's with 2344 horn now it's 2435's with PTH1010's. I use JBL M552/M553 in this set-up. They are your basic 24db LR analog actives made for S/R and Cinema systems. They work for me and are quiet as hell. These are in my main stereo/HT rig. I have a smaller system with 4344 wanabees biamped and use a JBL DX-1 there. The DX-1 is a real nice sounding crossover but unfortunately they are few and far between. If you ever see one grab it.

    Rob

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    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by merlin View Post
    ...are any of you using high quality active filters in your systems, and if so which?

    I've been looking at the likes of DEQX but would prefer to not subject my lovely forty year old vinyl collection to a rather crude A-D process unless someone is going to tell me it's transparent.
    I would recommend the Pass Labs XVR1 crossover or some of the better Marchand crossovers... I haven't directly compared either of them to the Bryston 10B, but others who have say that while the 10B is far more transparent than the Ashly, Rane, and Behringer club the Bryston isn't in the same league as the Pass Labs and some of the Marchands.

    http://www.passlabs.com/downloads/xvr1_lit.pdf

    This review of Magico's Ultimates also compares a DEQX and Marchand approach with the Ultimates. I have also heard the Ultimates paired with the Pass Labs XVR1... that would be my all analog choice.

    http://www.magico.net/MAGICO_Ultimate.pdf


    As for the digital transparency of the DEQX... for an analog front end, I agree the idea of needlessly digitizing the signal goes against the grain... I will say that running the DEQX with a CD as source, it sounds as good as I have heard that format.

    Quote Originally Posted by merlin View Post
    I know Widget is using one. How is it and what's the rest of the setup?
    I use a balanced DEQX PDC 2.6P (pre-amp version) I feed it a PCM bit stream from a Sony player. In my current setup the outputs of the DEQX feed a pair of 845 based SETs up top, a pair of 200 wpc KT-88 based push-pull mono blocks for the midbass, and a massive QSC sourced JBL MPA 600 on the subs below 50Hz. That's it. Digital source, DEQX, amps. Done.

    I intend to try an Alesis MasterLink playing 24/96 recordings of some vinyl... since DEQX is 24/96 native there will be no additional dithering or noise shaping... based on the excellent reports I have heard of the MasterLink recordings... I am hopeful that this will capture the sonic excellence of pure analog, with the convenience of digital.


    Widget

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    Many thanks for the replies gentlemen. Was there talk of a DIY version of the Passlabs at some point?

    Thanks also for the advice on caps Baron. I was thinking of keeping the analogue compensation filters in place if I go the analogue route, which would of course solve the issue anyway as you say.

    Widget, I was thinking along similar lines to you vis a vis vinyl - I'm getting too old and lazy to get up every twenty minutes or so. I'd got my eye on the Tascam DV RA1000HD myself - simply because of the opportunity to archive in DSD as well but I'm unsure as to whether this would be overly compatible with the DEQX. Another possibility is something like an Apple with Pure Vinyl.

    Thanks again

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    Quote Originally Posted by merlin View Post
    (snip)

    Another possibility is something like an Apple with Pure Vinyl.

    Thanks again
    HS, Batman, how did I miss that? That looks like a whole lot more potential than the simplistic Finyl Vinyl software.

    Thanks for that.

  10. #10
    Administrator Robh3606's Avatar
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    Apple with Pure Vinyl.
    Just curious but what are the advantages asside from using a good wave editor as far as sound Quality??? Has anyone used it??? Looks like it has elements of Cool Edit with the pop and click removal.

    Rob

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    RIP 2013 Rolf's Avatar
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    Quote Originally Posted by Titanium Dome View Post
    HS, Batman, how did I miss that? That looks like a whole lot more potential than the simplistic Finyl Vinyl software.

    Thanks for that.
    Pure Vinyl ... How come some (seems like a lot) does not accept that the world and technology is moving forward?

  12. #12
    Administrator Robh3606's Avatar
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    Pure Vinyl ... How come some (seems like a lot) does not accept that the world and technology is moving forward?
    Well I think there is more to it than that. I enjoy SACD and DVD 24/96 but still have 80% of my vinyl. About 3 years ago I would have been very interested in this software. I "rescued" some of my vinyl that never made it to CD and probably never will. The real problem is there still is a massive amount of material that will never make the leap to CD because they don't see a market for it. I archived some of my MF Halfspeeds at the time as well so I didn't play them to death. I don't want to get into the vinyl vs. CD debate however I was a very late adopter for CD. I still think some of the MF Half Speeds and the Direct to Disks are some of the best software bar none available in any format. Just like any other format there were a huge number of dogs as well. All the people that harp on CD, if they were not around then, don't realize the QC problems with mass produced vinyl. I grew up with records and will always have a soft spot for them.

    Rob

  13. #13
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    Marchand makes nice sounding analog crossovers, in kit form, or fully assembled. Whatever slopes and filter types you desire. They also make a really nice tube xover, utilizing 12AX7,s, but, beware, PRICEY for this particular model. www.marchandelec.com. Also, note that Marchand offers delay and baffle step correction, as options.

    You could also try sourcing some vintage electronic crossovers, like the Crown MX-4,s. Very clean, very nice sounding, but, hard to find.

    Some here also like the Ashly analog crossovers, also attractively priced. www.ashlyaudio.com
    scottyj

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    Senior Member Ian Mackenzie's Avatar
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    Quote Originally Posted by merlin View Post
    Many thanks for the replies gentlemen. Was there talk of a DIY version of the Passlabs at some point?


    Thanks again
    Yes there is....go to diyaudio.com under the Passlabs forum.

    It been very popular and quite a sucessful project. You need to know how to solder and lots of time. Should not be problem over the U.K winter!

    Macka

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    In the old days (early '70's), I used a Pioneer SF-700 in my triamped PA system, but the SF-850s are also nice. And these predate digital. These can still be found for ~$300.




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