Technically a 3 way, as the upper two drivers are high -pass filtered, even though all the drivers are identical.
BSC? Don't think so, as there's resistive attenuation of the lower two drivers. And they were probably intended to be used against the wall. Certainly sound best that way around here.
The likely reason for making it a 3 way is to reduce the excursion of the upper two drivers, in the interest of cleaner mid-range at high levels.
But counter to that, having electrolytic caps in series with the drivers is bad for resolution at any level.
Which is probably the conclusion Mission came to when they re-engineered the design for the Freedom.
BSC? Don't think so, as there's resistive attenuation of the lower two drivers. And they were probably intended to be used against the wall. Certainly sound best that way around here.
The likely reason for making it a 3 way is to reduce the excursion of the upper two drivers, in the interest of cleaner mid-range at high levels.
But counter to that, having electrolytic caps in series with the drivers is bad for resolution at any level.
Which is probably the conclusion Mission came to when they re-engineered the design for the Freedom.
Hi guys- I'm new to HiFi and believe I set up my kit incorrectly, I'm hoping someone might have some advice on how I can improve bass from some Missions 753s I just picked up. Got them from a buddy, who demo'd them with a nice amp (not sure make/model) and got some decent sounding bass out of them. I just bought an NAD C317BEE (also demo'd with the seller's floorstanders, which got killer bass out of the NAD), hooked it up to the Missions and am really disappointed with the power of the bass. There was almost nothing there with some bass heavy music, I cranked the Bass dial all the way up and got a barely tolerable amount of bass, but nothing close to what my buddy was able to draw from his amp.
I've connected the speakers using 12 or 14 gauge wire (it's pretty thick, I think it's 12), and tested my mac and android phones as input sources using an admittedly shitty headphone jack-to-RCA cable. I tried increasing the bass frequencies in iTunes on the Mac, but that just resulted in distortion (even at low volume--the 4" woofer cones weren't even visibly vibrating). Note that the Missions have input posts for both LF and HF, and I've connected the NAD to the LF posts, with a brass bar connecting the two posts (same setup during the demo that produced great bass).
The bass is so low I feel like I must be doing something wrong. Thanks for anyone who has ideas/help!
I've connected the speakers using 12 or 14 gauge wire (it's pretty thick, I think it's 12), and tested my mac and android phones as input sources using an admittedly shitty headphone jack-to-RCA cable. I tried increasing the bass frequencies in iTunes on the Mac, but that just resulted in distortion (even at low volume--the 4" woofer cones weren't even visibly vibrating). Note that the Missions have input posts for both LF and HF, and I've connected the NAD to the LF posts, with a brass bar connecting the two posts (same setup during the demo that produced great bass).
The bass is so low I feel like I must be doing something wrong. Thanks for anyone who has ideas/help!
It's certainly worth knowing the DC resistance of the midbasses, if only to sim it properly and know what the impedance will be. This one is easily modded.
boxsim-db.de | Boxsim Projektdatenbank
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I'm guessing these are 8 ohm nominal.
Two ways to lift bass. One to simply raise level, two to depress the midrange. Of course placing close to the wall lifts bass too.
I thought the simplest plan here is to depress the mid with a bigger coil. Looks doable. Replace the mid coil with about 1.8 mH and short out the 470uF caps. Taking the bass up 1-2dB by losing the caps and depressing the mid 2dB is quite a lot.
1.80 mH Ferrite Inductor
You could also lift the bass or increase its slope with a 3-4mH rather than 2.45mH at the input:
4.00mH Ferrite Inductor
In fact there is scope to reuse the 2.45mH in the mid filter. It fits.
The mid changes look like this. Ignore the low 3-4 ohm impedance, I simmed it as a 2.5 way with single drivers. The tweeter needs a 2.2R 7W wirewound to match the new mid level. or 1.5R series in front and 22R shunt after the filter, which sounds better IMO.
I buy ceramic/wirewound resistors at Maplin for about 70P. Don't get too prissy about exact values, and remember you can unwind coils to smaller values easily enough. Inductance is the square of the number of turns, so you don't take off much.
boxsim-db.de | Boxsim Projektdatenbank
Downloads
I'm guessing these are 8 ohm nominal.
Two ways to lift bass. One to simply raise level, two to depress the midrange. Of course placing close to the wall lifts bass too.
I thought the simplest plan here is to depress the mid with a bigger coil. Looks doable. Replace the mid coil with about 1.8 mH and short out the 470uF caps. Taking the bass up 1-2dB by losing the caps and depressing the mid 2dB is quite a lot.
1.80 mH Ferrite Inductor
You could also lift the bass or increase its slope with a 3-4mH rather than 2.45mH at the input:
4.00mH Ferrite Inductor
In fact there is scope to reuse the 2.45mH in the mid filter. It fits.
The mid changes look like this. Ignore the low 3-4 ohm impedance, I simmed it as a 2.5 way with single drivers. The tweeter needs a 2.2R 7W wirewound to match the new mid level. or 1.5R series in front and 22R shunt after the filter, which sounds better IMO.
I buy ceramic/wirewound resistors at Maplin for about 70P. Don't get too prissy about exact values, and remember you can unwind coils to smaller values easily enough. Inductance is the square of the number of turns, so you don't take off much.
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Hi Audiomark.
I don't kow if you're still partecipating here but I hope so.
I was reading your posts here as I bought some second hand 753 Freedom's. I think the lack of low's is just my case and I found a confirm of my fear that the wiring and stuff inside is a really cheap one when I read your posts.
May you help me telling me if I could bypass my lower bass crossover section resistances too as you did in the original 753's? Did you maybe manage to find any further tweak? Somebody is also helping me on another forum and they asked me to ask someone else the DCR between the - and + of low's section, if you may. That would be much appreciated.
Here is the schematics of my crossover I've drawn: