DIY biamp 6-24 crossover

Jump to Latest
#1,743
Yes, presumably. I was confusing the cables in the picture, assuming one pair loops back into the panel to feed the other xo. Looking closer I see that the cables are probably not feeding back into the panel and actually all heading to the respective amps. I'm planning on having full In/Out ports available using 3.5mm jacks and patch cables so in that situation the cables will get patched back in vs hardwiring.
 
#1,745
No, I'm basically planning for a 3-way option but with capability to add third board for 4-way. The "patch cables" are just my idea for retaining connection flexibility without a bunch of clunky RCA. BUT...I hadn't considered doing it the way you've done, so I'm rethinking the strategy.
 
  • Like
Reactions: maFrodite
#1,749
davidkou said:
I believe there is no stereo info below about 100Hz in vinyl anyway.
Click to expand...
David, I have been mastering for vinyl for over 50 years, and I can assure you that there is stereo information below 100 Hz on many many LP's.

We sometimes have to decrease the amount of separation in the low end in order to get a playable record, but it's customary to process only when necessary, and with as light a hand as we can get away with. This fact of life has led some people to repeat the fallacy that every record has all the low end completely mono. When I have to address the instances with excessive stereo spread at very low frequencies I use tools that allow the flexibility to narrow it down without going full mono, and I believe the same applies in most quality mastering houses.

Of course there are some cutters who want to make their life easier and simply leave a brute force mono-izer in the circuit at all times. That's another unfortunate fact of life.
 
  • Like
Reactions: davidkou and stajo
#1,750
At present I don’t cut my mains and let them play as they fall which is pretty steep below 40. It’s 15 inch tqwt. I have instead dialed back my subs to the lowest built in crossover setting, which makes the fall about as steep upwards but from 60-80. It works decently but I’m thinking my next active filter build will be 3-way and cut the lower at 40.

Both the mains and the subs and them together has a peak at 40 that I haven’t figured out why yet. The room nodes length wise is 23 (first), and that one is clearly present, and should be 47 (length second and whith first), but it shows up at 40 instead. It doesn’t calculate to be SBIR either.

Anyway, I’ve been pondering if I should monoize the subs or not. To me it can sometimes be wise and sometimes not.

I’m thinking that I can run in to that the total sub signal strength gets different regarding wether the source contains info on those bands on both channels or not if I just sum them with resistors?

Thoughts? Leave em apart and trust the mix or sum?
 
#1,753
Bodyslam said:
We sometimes have to decrease the amount of separation in the low end in order to get a playable record, but it's customary to process only when necessary, and with as light a hand as we can get away with. This fact of life has led some people to repeat the fallacy that every record has all the low end completely mono. When I have to address the instances with excessive stereo spread at very low frequencies I use tools that allow the flexibility to narrow it down without going full mono, and I believe the same applies in most quality mastering houses.
Click to expand...
Could you give a rough idea what might be a typical loss of stereo separation when mixing down to mono below say 120Hz when playing warped vinyl?
 
#1,754
What's the maximum interval of frequency cut that can be achieved for a given setting of the caps. I'd like to have a 24db/oct xover adjustable between 70Hz and 110Hz, si that possible? I plan to set it to 80Hz, but I'd like to have the freedom to adjust a bit below and above.
 
#1,755
Hello piecor,

this is already designed into the filtersections of the 6-24AXO by Mr. Pass. This is the reason why you have
a fixed resistor (10 kOhm) followed by a potentiometer (50 kohm) to adjust the R-value in the RC-filters.
Now you can play with the simulator of M. Rothacher (see my post #1752) and adjust the resistor values and the capacitor values to your desired crossover frequency (mid point 80 Hz) and try to find a value in the r-section of the filter which will be around 20 - 30 kOhm (10kOhm resistor + potentiometer adjusted to 10-20 Kohm / in series).
I showed my values for my subwoofer-6-24-AXO in this thread. You can copy them or make your own.
My one works very nice.
Cheers
Dirk 😉
 
#1,759
Hello piecor,

there are sure many formulas to determin different values for an R-C-filter.
There are also many online calculators on the internet. Use a search machine (g...le,...) and insert
R-C-filter - calculator...
It is much easier to use the simulator of M. Rothacher. You have to decide what slope (I prefer a 24dB-
slope for subwoofers) and what values are available for the the caps (this is why I have chosen 100nF and 47nF for the Cs in the filter) and then play with the R-Values and watch the filter curve. Also important is the phase.

You have my values in post #1584 for 90 Hz. Insert them in the simulation and play with the R- values.
But it also depends on the behaviour of your loudspeakerchassis. Do you want to cut-off in the 'linear' region of the speakers spl-curve or do you want to use its 'natural' roll off also,...
And you can see in the filter curve, where the -6dB point circa is.
I would build it only on the pcb and on a wooden board and would adjust the R - trimpots as determined in
the simulation - and listen.
You can also use a microphone and an A/D-converter and measure your results at the speaker (with a software / ARTA for example)).
Cheers
Dirk
 
  • Thank You
Reactions: G600
You must log in or register to reply here.
Top Bottom