About active Xovers, Remember how much trouble finding a transparent preamp for your systema has been? now double that for an active xover, since they usually have more amplifying stages than a preamp.
Use Passive line level xovers between your preamp and amp, 6 db is pretty easy, this will help mostly the amp!
And of course keep the internal xover as designed.
Since you are putting new external xovers, it would be good to identify tha parts in the Xover. The biggest upgrade you can make is to take out the Lpad, resitors at speaker level are very harmful to sound. When Multiamping you can control the volume for each driver from each amp driving it...this will be a lot of fun to play around with and most rewarding!
Dont change resitors, dump them! Change the Solens first! |
Okay just jumping in on this thread and sorry.....I am thinking of adding a sub woofer or two to my current system....the best way to do this is WITH a crossover .....so any ideas or suggestions ??? |
Correct. The new passive crossovers will be external. I will keep the original crossovers intact for comparison or if one day I decide to sell. It will be a long multi step process. The first step will use original solen caps and inductors, replacing all resistors with duelund. The second step will be to replace the most critical caps in the circuits of the tweeter and 5" mids. Then the most important components, mostly inductors, in the 8" and 15" path. Then possibly the less critical components. I am thinking about using dh labs Q-10 wire and Mundorf supreme solder. I am wondering what would be the best connectors for the 14 driver wires, since I don't think soldering and desoldering repeatedly is the best way. Any suggestions? |
Another idea is to put your crossover external to the speakers. That way one can make changes to capacitors, resistors and wireing to dial in the speaker. It also elimates a source of distorition as the crossover in the speaker is under a lot of pressure from the woofers. |
Given that the crossover of the SC-VI does have a lot of driver compensation, perhaps best is just to:
1) upgrade the critical components of the 4 way passive crossover.
2) bi-amp using one amp for the tweeter and 5"mid, and one amp for the 8" and 15" woofers. I would have the added control of having two amps per speaker. Should I feed the whole signal to the amps, or put a Pass XVR-1 between the preamp and the four mono-amps? If I feed the whole signal to each amp, the four way crossovers in the speakers would be able to deal with it, as they already do now. There are to pairs of binding post, the to goes to tweeter and 5", the bottom goes to 8" and 15" portion of the crossover.
3) I could possibly use the DEQX HDP-4 in-line Digital to Digital, before the Playback Designs MPS-5 and Krell Phantom, so I would not be using the DAC and PRE stages of the DEQX. I stopped using the TACT 2.2X Digital to Digital because it decreased substantially the level of detail. How good is a DEQX HDP-4 D to D? Much more transparent than the TACT?
What do you think?
Thanks. |
Thank you!
I am reading the Loudspeaker Design cookbook.
For all I have read, considering the 4-way crossover of the Dunlavy SC-VI has 34 components doing a lot of equalization, it believe I will go with the path of just upgrading the components of the crossover for now and listen to the effect of each component upgrade, starting with the most critical ones.
Sometime in the future I may try the active crossover path, but in a way that I can compare with the upgraded passive crossover. Perhaps with the Holm or DEQX. |
FWIW, Both my main and bed-room systems are actively tri-amplified and I've heard other successful and unsuccessful realizations. I was quite happy to leverage Siegfried Linkwitz's (as in Linkwitz-Riley) design work which just left the soldering to me.
>What are the best active crossovers?
The answer is most likely irrelevant to you because you don't yet have the background to recognize what you need.
Read _Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms_ by Floyd Toole for an idea of design targets and _The Loudspeaker Design Cookbook_ by Vance Dickson for some information on realizing those targets.
>I have a pair of Dunlavy SC-VI, which are four-way 6db slope crossover.
The cross-over network also compensates for driver resonances, applies baffle step compensation, and accommodates the rising response which goes with drivers with low inductance motors as they become acoustically large.
Some of John Dunlavy's cross-overs also adjusted driver Q which in turn affects what happens moving farther beyond the driver's pass-band, phase, and how the speaker sums within the driver's pass-band.
Krell's manual suggests that this can be accommodated, although that would mean paying some one for custom work and you still have topology issues to deal with.
Other generic active cross-overs lack any provision for that sort of thing and won't work well for you. The Pass XVR-1 isn't enough.
>I understand I would need to use Three Krell KBX in series to get 4-way 6db slope (besides 8 channels of amplification).
That won't duplicate your existing cross-over functions that have a lot to do with how your speakers sound.
Passive cross-overs are usually realized using band-pass filters on all but the woofer (low-pass only) and tweeter (high-pass) only. By cascading filters instead of using band-pass filters on the upper and lower midrange drivers you're going to change their phase relative to each other, how they sum, and what needs to be done to their relative levels to compensate. That changes your problem from copying to cross-over design which is a lot more complicated.
>Do you know of any high quality 4-way active crossover that can be configured to 6db slope (except for the 3x KBX option)?
The mini-DSP 2x4 will work for your purpose. Of course, using it will require measuring your passive cross-over transfer functions, and creating DSP filters to match.
That said, if you like your speakers you're better off not trying to "improve" things via active-cross overs unless you can purchase a unit specifically designed for your speakers.
If you want a DIY construction project (perhaps active) find a respected design and build it.
If you want to get into speaker and cross-over design as a hobby after reading both books I referenced, buy yourself some measurement software + hardware, perhaps some cross-over optimization software if you care to do passive speakers, and start with a 2-way. |
Pass Labs XVR1. Analoge xover. |
http://conciertomusicsystems.com/ACTIVE_CROSSOVERS_EQUALIZERS_&_AMPLIFIERS.htm |
The trade-off for increased complexity is having a dedicated amp on the woofers, which can be a good thing. It depends -- there are too many variables to contemplate. You have to hear it to know. |
Why even bother with going to outboard active crossovers? Just upgrade the existing passive crossover. Going active, particularly analog, will greatly increase the complexity of your system. I'm not sure the increased complexity will be worth the sonic advantages, if any. |
Hello,
Thank you for your responses!
Peter, Digimoda seems Interesting. I never had Class D amplification in my system, only Class A amplification, so I wonder if it could be better. I usually read that Class A sounds better than Class D.
Marty, Regarding DEQX, it seems interesting. In principle I don't like very much the idea of inserting a AD and DA into the signal path, being happy with my Playback Designs + Krell Phanton path, but certainly I can only know for sure if I eventually try it.
Ngjockey, Regarding Holm, it seems quite interesting, but again I wonder if it would sound better than Playback Designs + Krell Phanton +Active analog crossover. I guess I would need to try to know for sure.
I guess these are all very interesting and radical alternatives. I wonder if I will be able to compare them against the simpler option of just upgrading the crossover components of my SC-VIs crossovers, something that I am already doing or inserting an audiophile quality active analog crossover.
Would anyone know about an analog competitor to the KBX crossover? A better, and possibly more modern, audiophile level active analog crossover?
Thank you!
|
Can't think of any 6dB active analog xovers. Like the Digmoda idea but still wary about class D for tweeters. As far as a separate crossover, other digital options are Xilica (might be the best of the 'pro' stuff and stand-alone option for 8 out), Ground Sound, miniDSP and, of course, Behringer (no comment). Full-blown preamp/RTA/correction and up to 3-way are DEQX and Holm Acoustics (interesting tutorial on website). No law that it has to be entirely active, other than trying to duplicate or improve upon the existing passive PCB - particularly the mid/tweeter xover. Then, there's software/computer based xovers and RTA's. Thuneau Allocator is just one of many but really haven't done much homework here.
Hypex amps/modules might be interesting for this project as well. Not like the SC4 isn't big enough.
http://www.stereophile.com/content/dunlavy-audio-labs-sc-iva-loudspeaker-specifications
...."(frequencies not specified)" |
If you're using strictly digital sources, and you're open to something completely different....
You might think about a DEQX (or similar) digital domain x-over/preamp. These are 3 way units, so the mid and tweeter will still need to be jumpered. However, in addition to the overall theoretical advantages of crossing in the digital domain, these units also provide digital room correction (which I find compelling). This might be particularly useful to your application, because (as Minor1 noted) any missing notch filters or other FR correction built-into the passive x-overs in your speakers will be less problematic with DRC.
I understand that this is a different approach and not for everybody. Just thought it was worth bringing to your attention.
Marty |
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Minorl , that be hard with the Dunlavy's - and with the Digmoda you can do all the "shaping" you'd want. |
You have to be careful purchasing active crossovers for speakers. Some (not all) speakers need some sort of wave shaping circuitry to correct for issues inherent to the specific speakers. Martin Logans for example. So, when thinking about purchasing a third party's active crossover, contact the speaker manufacturer first and ask if wave shaping is required or if the third party active crossover will be okay for the speaker.
enjoy |
Buy 4 Digmoda Ice power based amplifier with DSP signal processing, can be configured in a number of different variations. A DDC1000 for the woofers and a DDC552 for the mid woofers midrange and tweeter per speaker. The 552 is a 3 channel with 2ea 500W modules and a 250W module, the DDC1000 is a single 1000W module. Then - go to town with you laptop and play around with slopes / crossover points etc. the software is very easy to use and understand. A much better solution than any active crossover. Google them for more information
Best of luck
Peter |
