I've had a pair of Mission 782 as part of my system for the past 14-15 years or so and I still really like them. They needed the mid drivers replacing when I bought them but thankfully Mission still held spares at the time.
Recently I've been thinking about upgrading the speakers to the final SE spec, which included upgraded components in the crossovers and some newer tweeters. I missed out on buying some crossovers on eBay, but the seller suggested just upgrading the original ones with better components. What are peoples thoughts about this? I know some will say it makes no difference, but looking at the current design and components there seem to be some improvements that can be made.
The original crossover looks like this:
![[IMG]](https://live.staticflickr.com/65535/51796862716_35a208e988_c.jpg "[IMG]")
Tweeter and Mid driver
![[IMG]](https://live.staticflickr.com/65535/51796983573_2a87906c2c_c.jpg "[IMG]")
Woofer
I've traced it all out to this circuit:
![[IMG]](https://live.staticflickr.com/65535/51795915167_1de2b29de5_o.jpg "[IMG]")
The crossover points are supposed to be 195Hz and 2.5kHz
It seems to me that for starters the resistors could all be changed to wire wound resistors of suitable wattage (Mills or Ohmite), and then the HF cap changed to a more modern poly film from someone like ClarityCap. The back to back electrolytics that are bypassing the woofer are an obvious thing to change too. They are a cheap way to get a bipolar capacitor, but a real no-no in some design circles - so replacing both of them with a single bipolar 470uF electrolytic seems sensible.
I guess replacing the inline MF caps would also help, three larger electrolytics and a smaller film cap. My guess is that it is a cheap way to produce 102uF with the quality of the poly cap handling the higher frequencies. The electrolytics are cheap enough to replace while I am there, and again the film caps could be changed to some nicer ones from ClarityCap.
It is interesting to note that Mission themselves used better poly caps in the SE crossover, and dispensed with the back to back capacitors configuration for the woofer. Although it seems they incorporated a higher order filter for the mid section. The polarity of the woofer seems to be swapped too, the HF cap is a higher value as well (6.8uF).
Here is a picture of the SE crossover (x2):
![[IMG]](https://live.staticflickr.com/65535/51795915277_4ae67dc264_c.jpg "[IMG]")
I'd be interested to hear people's thoughts before I order some parts.
Recently I've been thinking about upgrading the speakers to the final SE spec, which included upgraded components in the crossovers and some newer tweeters. I missed out on buying some crossovers on eBay, but the seller suggested just upgrading the original ones with better components. What are peoples thoughts about this? I know some will say it makes no difference, but looking at the current design and components there seem to be some improvements that can be made.
The original crossover looks like this:
Tweeter and Mid driver
Woofer
I've traced it all out to this circuit:
The crossover points are supposed to be 195Hz and 2.5kHz
It seems to me that for starters the resistors could all be changed to wire wound resistors of suitable wattage (Mills or Ohmite), and then the HF cap changed to a more modern poly film from someone like ClarityCap. The back to back electrolytics that are bypassing the woofer are an obvious thing to change too. They are a cheap way to get a bipolar capacitor, but a real no-no in some design circles - so replacing both of them with a single bipolar 470uF electrolytic seems sensible.
I guess replacing the inline MF caps would also help, three larger electrolytics and a smaller film cap. My guess is that it is a cheap way to produce 102uF with the quality of the poly cap handling the higher frequencies. The electrolytics are cheap enough to replace while I am there, and again the film caps could be changed to some nicer ones from ClarityCap.
It is interesting to note that Mission themselves used better poly caps in the SE crossover, and dispensed with the back to back capacitors configuration for the woofer. Although it seems they incorporated a higher order filter for the mid section. The polarity of the woofer seems to be swapped too, the HF cap is a higher value as well (6.8uF).
Here is a picture of the SE crossover (x2):
I'd be interested to hear people's thoughts before I order some parts.
Here are some component ideas:
ClarityCap ESA 4.7uF 250V and 2 x Mills 8R2 5W resistor for the HF.
3 x Jantzen eLeCap 33uF 100V + ClarityCap PX 2.7uF 250V for the series capacitance on the MF - because the original electrolytics were 32uF I reduced the film cap to keep the capacitance the same.
Jantzen eLeCap 15uF 100V, Ohmite 3R9 10W and ClarityCap PX 6.8uF 250V for the rest of the MF components.
And finally replace 2 LF capacitors with a single Jantzen eLeCap 470uF 100V cap (replace the 2 polarised with 1 bipolar cap) and 2 Ohmite 4R7 10W resistors.
Is replacing everything apart from the inductors overkill? I would appreciate people's thoughts.
ClarityCap ESA 4.7uF 250V and 2 x Mills 8R2 5W resistor for the HF.
3 x Jantzen eLeCap 33uF 100V + ClarityCap PX 2.7uF 250V for the series capacitance on the MF - because the original electrolytics were 32uF I reduced the film cap to keep the capacitance the same.
Jantzen eLeCap 15uF 100V, Ohmite 3R9 10W and ClarityCap PX 6.8uF 250V for the rest of the MF components.
And finally replace 2 LF capacitors with a single Jantzen eLeCap 470uF 100V cap (replace the 2 polarised with 1 bipolar cap) and 2 Ohmite 4R7 10W resistors.
Is replacing everything apart from the inductors overkill? I would appreciate people's thoughts.
Personally.... With the cost of parts these days,
I'd replace all resistors with better wire wounds or metal films.
Anything but the harsh and grainy white things.
And all caps with better polypropylenes.
For the really large values if you need to be sensible in your budget, i'd use the biggest poly you can justify with an electro across it to get the needed value.
Brand and model is personal choice.
Everyone has their favorite.
If you happy with your choice, be happy 🙂
I'd replace all resistors with better wire wounds or metal films.
Anything but the harsh and grainy white things.
And all caps with better polypropylenes.
For the really large values if you need to be sensible in your budget, i'd use the biggest poly you can justify with an electro across it to get the needed value.
Brand and model is personal choice.
Everyone has their favorite.
If you happy with your choice, be happy 🙂
Thanks for the input - it seems that Mission did something similar with the original design. 3 x 32uF electrolytics with a 5.6uF poly - what do you think if I used 3 x 33uF electrolytics and a 2.7uF poly - Is the poly not big enough, I just don't want go over capacitance... Or I suppose I could use 2 x 47uF electrolytics and a 8.2uF poly - what do you think?
It sounds as though the seller wasn't really in to crossover networks. The real improvement comes from the circuit, ie the values. If these are as good as they can be then speaker setup and EQ.
Just did a quick Google search and the words bright and harsh get mentioned a lot.
They've most likely got a rising frequency response that no amount of component changes will fix.
I'd either look for replacement speakers or build some.
They've most likely got a rising frequency response that no amount of component changes will fix.
I'd either look for replacement speakers or build some.
3x32+5.6=101.6
i dont believe 10% either way will make any audible difference.
me personally id see if i could physically fit a 100 poly and be done with it.
its not stupid money, but your budget and size restrictions might make it not doable.
there are technical reasons why they may have used multiple electros.
or it couldve been done for budget reasons.
modern electros should be better than olden day electros so using multiple parallel caps is a messy pain to me.
I am one of those that believes in different parts having a different sound.
not all changes will make it sound better to all people.
these are your speakers, so the final choice is yours.
Hi there, I’m a newbie here, I was wondering if you have a diagram for a mission 707 crossover diagram?
I’m restoring my old speakers from the 90,’s and would like to upgrade the crossovers.
Thank you
Paul
I’m restoring my old speakers from the 90,’s and would like to upgrade the crossovers.
Thank you
Paul