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BMS 4592Nd Coax XO sugestion


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Im using BMS 4592Nd (16 Ohms) coax drivers in a pair of 200Hz Tractrix horns.

I´m currently using the 6300Hz original passive x-over for mid/high, but feels there must be potential for improvements here.

 

I would really appreciate if someone with similar setup could share the schematic for such a filter  

2.jpg

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Hi, and welcome to the forum. 

 

I've got DSP crossover settings for the 4592ND on a K-402 horn, but that probably isn't really close to your 200 Hz full tractrix horn, and it reflects the bi-amping settings that yielded the best results, i.e., the midrange channel is -2.5 dB from the tweeter channel, and the tweeter is delayed 0.145 ms (i.e., one full wavelength at 5.8 kHz).  If you can use any of that, I'll be happy to post them. 

 

Knowing now what I have learned about the 4592ND, I personally wouldn't try to use passive crossovers/monoamping since the improvement in sound quality is fairly significant when the delays and relative gains are corrected, as well as the SPL vs. frequency response.  It turns out that no crossover filters are actually needed in the 4592 if you bi-amp and correct the gains and delays.  It acts like and sounds like TAD TD-4002s that I use in the Jubilees on either side of the center K-402-MEH  and its phase/group delay response reflects that subjective observation.

 

Chris

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Thanks Chris, your text is very much appreciated

So far I have avoided dsp's of emotional reasons (I use only analogue sources and SE triode amps), because not beeing able to "see" and understand the complete signal chain makes me a bit nervous. I´m currently going 3-way having low-level 1st order LP-filter at 350Hz (bi amping), so going going dsp filter will require tri-amping and a 3 way DSP-unit. Hence a rather big change. Any suggestion which dsp-unit to try?

 

Quote

 It turns out that no crossover filters are actually needed in the 4592 if you bi-amp and correct the gains and delays

 

Just to understand you clearly.

With balanced gain and correct delay (and moderate sound levels) I could actually remove the 6K3 hz filter between Mid and Hi, without worry destroying the fragile HF diaphragm in the 4592Nd? 

  

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I generally recommend Xilica XP series (generally these are only available new), ElectroVoice DC-One (new or used), and Yamaha SP2060 DSP crossovers (used), with the Xilicas being preferred by a fairly large margin due to their lower noise floor and much better PC/MAC/Linux programmability (user interface) than the other two brands. 

 

The miniDSP 2x4 HD sounds good, but the noise floor might be higher such that you can hear it at the listening position.  Some people have inserted some attenuation in the HF channel to bring the sensitivity down a little, but I find that the noise level is pretty benign.  The cost difference between a Xilica XP2040 and the miniDSP 2x4 HD is about 4:1.  I don't recommend the "miniDSP 2x4" (not enough gain latitude before distorting), nor the miniDSP OpenDRC unit (too high noise floor), but the 4x10 HD is apparently quiet enough when using balanced (XLR) connections to your preamp and amplifiers. 

 

I also would not recommend Behringer crossovers due to their poor analog sections.

 

In other words, don't get too cheap when considering DSP crossovers for home hi-fi audio.  A DSP crossover is a major part of hi-fi reproduction (it's the main signal path) and the better designed and implemented DSP units are completely transparent, while the cheaper ones (mentioned above) aren't.  I think that's why so many people have heard bad things--from others using poorer quality units to "save money". 

 

The diaphragms in the 4592ND aren't "fragile".  They are in fact quite rugged, even more so than titanium dome diaphragms found in more typical compression drivers.  That's actually one of the key selling points of the ring radiator drivers: extreme ruggedness for commercial applications.  The driver diaphragms themselves roll off naturally at both very high and very low frequencies, and their input impedances rise below Fc if given a full-range signal, further protecting them. 

 

This crossover filter approach is the same schema used in the Danley Synergies--and they're good to 1000w input power continuous/4000w peak on the SH-50.

 

Chris

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1 hour ago, Chris A said:

The diaphragms in the 4592ND aren't "fragile".  They are in fact quite rugged...

 

BMS does publish a crossover frequency. I hope to get some 4592ND drivers some day and I will be inclined to follow the manufacturer's recommendation.

 

I have always considered one the main benefits of DSP is the precise crossover settings, to reduce the possibility of IM distortion caused when a driver gets input with signal beyond its useful audible range, especially when the power level is high.

 

I also recognize the important work that @Chris A is doing with timing, phase response and minimum crossover effects, and I believe his suggestions will result in the best sound from a home audio system built up in similar fashion to his fantastic system.

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132060987_BMS4592NDbenignandpassiveSPLresponseandHD.thumb.JPG.4d2bf649b0f412bd642e5a470411969a.JPG 

663587418_BMS4592NDimage.jpg.6a321d3a9e5105e878088cb7170d215e.jpgbms_catalogue_2015-5-18.jpg

 

I hate to say this, but the benign response of the 4592ND on the horn that they reference (but don't name) isn't quite "good enough" in my experience.  The vertical scale divisions are 2 dB increments in the above plot, so the response using the passive crossover at 7.2 kHz is about +5 dB, and the response at the nominal 5.8 kHz natural crossover frequency takes a dip in response that really calls for a boosting PEQ (something that you can't do with passive crossovers) of about 8 dB.  Additionally, the midrange diaphragm actually has about 2.5 dB too much sensitivity relative to the HF (tweeter) diaphragm.  Here are the settings that I use on the K-402-MEH for the midrange and HF channels to correct its response to about ±1.5 dB on-axis.

 

First the output channel PEQs of the midrange diaphragm:

 

1886917184_BMS4592NDonK-402midrangeXConsolescreenshot.thumb.JPG.b8feba99e09d1bab0a6bcf4a92a927cb.JPG

 

...then the HF diaphragm output PEQs:

 

241404496_BMS4592NDonK-402HF(tweeter)XConsolescreenshot.thumb.JPG.38de2b80d099907d4cd32ef855c86340.JPG

 

...and finally the input channel PEQs to correct the crossover region EQ nulls:

 

290059443_BMS4592NDonK-402inputPEQsscreenshotXConsole.thumb.JPG.9816f56dc63a6fcdc1e2e1e132030312.JPG

 

A YouTube video of the closely related BMS 4594 driver:

 

 

Chris

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Thank you Chris for this most valuable information. I guess DSP is the way to go. Still I´m and old dog, and as you know. It takes time for an old dog to learn how to sit. Going into the digital domain will take me time to adapt to. In the mean while I´ll try to get the 4592Nd to sing with passive filters.

 

@Deang 

I am very interested in what you posted above. Could you explicate it further.

I recall the two top images as the mid- respective hi-driver frequency response. But what is the difference between the grey respective red curve?

 

I guess the bottom right image is a topology that what Bill Woods designed for BMS 4590. Is this driver similar to the BMS 4592Nd implying that the same topology could be worth trying for me?

 

Is the bottom left image the frequency response of the BMS 4590 with the Bill Woods filter in use?

   

  

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I think that when you hear the difference, it won't take very long to "shift allegiances". 

 

By the way, part of my above DSP settings are also wrapped up with the input channels of the Xilica.  I added those PEQs to my posting above to smooth the crossover between the HF and midrange diaphragms, which naturally cross at ~5.8 kHz (three posts above).

 

Chris

 

 

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  • 1 year later...
  • 3 months later...

I am sorry for reviving an old post, but a custom filter by Bill Woods for BMS 4590 was shared here, but the picture is no longer available/hosted. Could anyone re-share? 

 

I would like to try a quality passive for this to test versus active.

 

Thank you

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  • 3 months later...

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