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-   -   B&C DCX464 build (https://www.diyaudio.com/forums/multi-way/360071-dcx464-build.html)

DocHodges 12th September 2020 12:58 PM

B&C DCX464 build
 
Hey guys I want to give building my own speakers a try. I’ve done diy subs in the past and even build several kit speakers but never a complete diy speaker. Based on my readings here the DCX464 seems like the best candidate to build the ultimate end game towers that can double for both HT and critical listening. If any one is familiar I would like to build something like the Diysg 1299s or realistically more like the JTR 212HT. Due to the size requirement of horns to fully load the 464 I am considering crossing it much higher than the 300hz it’s rated for. I can’t seem to find many build using this setup. Has anyone here built any speakers around this CD? If so I would love to hear your experiences and what you learned in the process.

mark100 12th September 2020 03:13 PM

Hi DocHodges, i think you're on the path to the easiest to build, truly killer rig, for both HT and critical listening, that i know of at least.

Right now, i have a dcx464 in a synergy, but i've had it on a xt-1464 for use in builds similar to what i think you are considering.
Look at post #125 for raw measurements and #128 for processed, in this thread B&C DCX464. btw, BMS works too ;)
Crossover is at 500Hz....i think you are right about needing a really large horn to load lower.
I've stayed at 500Hz, even for the big 49" x 28" synergy..........which admittedly may not load down low as well as a large commercial horn.

Personally, I'd decide what size i want the mids, in conjunction with matching the horn size to the mids, in a MTM config.
IOW, if using 12" mids I'd probably stick with the xt-1464. If using 8" mids, maybe one of the smaller 18-Sound horns JTR often uses....although you might need to raise xover up a little.

DocHodges 12th September 2020 03:43 PM

Quote:

Originally Posted by mark100 (https://www.diyaudio.com/forums/multi-way/360071-dcx464-build-post6338975.html#post6338975)
Hi DocHodges, i think you're on the path to the easiest to build, truly killer rig, for both HT and critical listening, that i know of at least.

Right now, i have a dcx464 in a synergy, but i've had it on a xt-1464 for use in builds similar to what i think you are considering.
Look at post #125 for raw measurements and #128 for processed, in this thread B&C DCX464. btw, BMS works too ;)
Crossover is at 500Hz....i think you are right about needing a really large horn to load lower.
I've stayed at 500Hz, even for the big 49" x 28" synergy..........which admittedly may not load down low as well as a large commercial horn.

Personally, I'd decide what size i want the mids, in conjunction with matching the horn size to the mids, in a MTM config.
IOW, if using 12" mids I'd probably stick with the xt-1464. If using 8" mids, maybe one of the smaller 18-Sound horns JTR often uses....although you might need to raise xover up a little.


Mark,
Thanks a ton for the reply. Itís your measurements and analysis that made me want to go this route. My thoughts are to go with the MTM using 12 inch mids for the towers and 10Ē mids for the center (size constraint). I have been kicking this build around for a while but the more I talk to people the more I realize that if I can build it and it lives up to my expectations then the audio community will really benefit as there currently isnít anything in the diy community like it. I would like to fully document the build and release it for anyone to replicate.

With that said the 1464 was actually the horn I had picked out! I wasnít sure of the performance with the 464 but thatís certainly reassuring that you suggested the same one. For the center channel using the 10Ē woofers I could fit the 1464 but will likely go down a size to allow for a slightly more compact design.

My challenge is there is so much information on crossover network that itís quite overwhelming. There is an excellent sticky thread Iíve been reading to learn but boy itís not easy. I would like to keep the design passive since I feel the majority of people who would build it would be hooking it up to external amplification like myself.

When you had your MTM build with the 1464 what woofer did you use? I think Iím going to shoot for somewhere around a 45-50hz LF +-3db

mark100 12th September 2020 04:42 PM

Glad to help :)
I really like BMS 18n862's for woofers. Either single sealed, single vented, or dual vented in PPSL....everything i've tried with this driver has worked awesome, all with the same f-3 tuning at 30Hz.

I oh so highly recommend you go multi-amp active. It will be easier to implement, and frankly offers higher SQ potential than passive, imnsho.
Even if you are dead set on passive, I'd tune active first and then duplicate as best you can with passive.
(I had a pair of JTR 3TX, that i triamped active...let's just say an already excellent speaker got mo' excellent ;))
The improvement in transients from multiamping, and getting timing and phase spot-on can be quite dramatic. Not to mention clarity and finesse.
Often sounds and feels like the dcx, mids, and 18n862's in whatever type build I'm using them in .....can drive nails and rip air apart!! :D

DocHodges 12th September 2020 04:49 PM

Quote:

Originally Posted by mark100 (https://www.diyaudio.com/forums/multi-way/360071-dcx464-build-post6339075.html#post6339075)
Glad to help :)
I really like BMS 18n862's for woofers. Either single sealed, single vented, or dual vented in PPSL....everything i've tried with this driver has worked awesome, all with the same f-3 tuning at 30Hz.

I oh so highly recommend you go multi-amp active. It will be easier to implement, and frankly offers higher SQ potential than passive, imnsho.
Even if you are dead set on passive, I'd tune active first and then duplicate as best you can with passive.
(I had a pair of JTR 3TX, that i triamped active...let's just say an already excellent speaker got mo' excellent ;))
The improvement in transients from multiamping, and getting timing and phase spot-on can be quite dramatic. Not to mention clarity and finesse.
Often sounds and feels like the dcx, mids, and 18n862's in whatever type build I'm using them in .....can drive nails and rip air apart!! :D

Great points for sure. I have no problem going active especially if they will be significantly better for sure. That said what amp/dsp are you using. Iím really happy with my emotiva DR3 amp currently. Iíll admit I havenít looked into active crossover gear too much but when I do I keep seeing the minidsp recommended. I use that for my subwoofers but I just canít see how they would be any good for LCR. It just seems way too noisy for me. If I can find the best setup for active crossing Iíll happily sell my dr3 and go that route for sure.

mark100 12th September 2020 06:10 PM

Which minidsp are you using for your subs? That is too noisy?
I'd probably suggest you try the 2x4HD to dial in the tuning on your dcx & mid build.
Just use the 3 channels of your DR3 amp to tune in a single box...then make a decision on which way to proceed. You'd only be out a little over $200, and have gained a ton of knowledge.
I believe Cowanaudio made a good passive xover for between the two dcx sections...might be a good way to go if you want to stay active, but need to reduce channel counts

I use QSC amps and processorsas I find much more value and functionality with pro install gear than with home audio.
A q-sys Core110f processor is ideal for multi-way builds imo. They go on ebay pretty regularly for $1200-$1500. They have 8 balanced/unbalanced inputs, 8 outs, and an additional 8 that can be configured as either in or out. And all with more configurable xover, EQ, and delay functionality than probably ever seen (includes FIR).
Used 4 and 8 channel CX series amps can be had for under $300 with a little patience.
Just my route though.....

LineSource 16th September 2020 04:16 AM

DCX464 midrange SPL frequency measurements suggest potential benefits from adding a copper ring on the midrange motor to reduce inductance in an effort to smooth and extend midrange ring radiator high frequency.

oLjud 16th September 2020 06:09 AM

Quote:

Originally Posted by LineSource (https://www.diyaudio.com/forums/multi-way/360071-dcx464-build-post6342909.html#post6342909)
DCX464 midrange SPL frequency measurements suggest potential benefits from adding a copper ring on the midrange motor to reduce inductance in an effort to smooth and extend midrange ring radiator high frequency.

And why wouldnt B&C fix this before if its beneficial?
Any idea how it can be implemented or is it just a random though you have?

Please tell more.

LineSource 19th September 2020 02:23 AM

1 Attachment(s)
"And why wouldn't B&C fix this before if its beneficial?"

Adding a copper ring in the motor typically smooths the impedance plus extends and smooths high frequency. Dimishing returns from this type of investment is more important to home perfection audio than higher sales volume ProAudio customers.

The AudioExpress magazine impedance measurements of the 16-ohm version(12-ohm nominal) midrange varies from 5-ohms to 50-ohms, with 3 large peaks and rising with high frequency. The frequency measurements show two humps in the crossover region from 3,000-6,000Hz. I was hoping to use passive 1st order C & L crossovers. Posted 2nd and 3rd order circuits are commonly used.

To Dream the Impossible Dream... an audio point source covering 400-20kHz with both smooth frequency response and smooth phase response. Medical research on human hearing warns about multi-driver speakers having the harmonics out of phase from the fundamental.

cowanaudio 19th September 2020 08:09 AM

You won't get anywhere close to smooth amplitude and phase response with a first order filter with these drivers. A well behaved passive crossover is pretty complex.

400Hz is the easy bit, they can go lower in a domestic environment.

Any references to read about "Medical research on human hearing warns about multi-driver speakers having the harmonics out of phase from the fundamental."? My experiments have shown the human ear is pretty insensitive to smooth phase rotation throughout the frequency spectrum.


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