Tweaking existing speakers

[Geoffroy]

Good morning to all,

I just got for cheap a pair of Mission 700 (the ones with the medium/bass driver above the tweeter) that I was planning to use for experimenting. As with any new thing I try I like to learn by trying something that works first and then tweak it to suit if needed. Would anyone have completed successfully a project using the mission 700 cabinets? And if yes what did you do for that? My objective for the moment is just to use them as a learning tool meaning that I'd like to operate small tweaks (basically modifying anything but the cabinets....) to improve the listeninig experience (which seriously lacks mediums and trebles.....).

For info, I use a lm1875 gainclone amp with them and it did have a wonderful sound with my test driver (a cheap £4 one connected without any electronics of any kind).

Any advice on where to start from would be very very helpful.


Cheers

Geoffroy

[picowallspeaker]

(which seriously lacks mediums and trebles.....).

Why ? For the size , those are the frequencies where those speakers would be addressed to .

[Inductor]

Geoffroy,
Try to post a picture of your speakers xover (and front baffle if you can), or a scheme of it if you have one. If you have doubts about the sound, start whit one easy test (1.test), if you can (thats what I would do), and test the main driver with no xover (connected to the amp) for some time, for checks only & see if you like the sound, and next connect with the mid-woofer (low frequencies) xover and make your 2.test for the sound (have in mind that the tweeter is not connectect - high frequencies). Everything should be good at this point and we should have a pic/photo by then. Have fun. (Second phase; looking at the tweeter and xover to see if everything is fine and maybe you need good quality caps or maybe a new Polyswitch)

[wintermute]

first thing I'd check is whether the tweeters are actually working or not... at a very low volume level with the speaker grills off, put your ear up to the tweeter to make sure it is actually producing music

I'm assuming that the speakers don't have an adjustable LPAD (some do) if it does it is like a level control for your tweeter, you can turn it up and down to suit your needs.

There may be a fixed value LPAD in the crossover network, adjusting (or even removing) this should bring up the brightness of the tweeter (removing may be too much depending on the difference in sensitivity between the woofer and the tweeter).

Another thing to consider is the speaker placement, They may have a lot of BSC in which case if you put them close to the walls (or even worse in a corner) then they will have more prominent bass (than maybe the designer intended). Try moving them out from the wall(s) and see if that makes a difference.

Tony.

[Geoffroy]

Well here are pictures of front and back. I cannot open them tody as I miss the TORX screwdriver (just discovered what it is...). More pics later.

I moved them away from the wall it is a bit better but not amazing. When listening to the soundtrack from Blade Runner the medium come out ok but anything else was nice but not spicy, worse being opera but I won t complain too much this is already MUCH better than the pc speakers I used to listen to so......

[Inductor]

You can also help (with another test/little different sound) closing one/or both vents (with a round sponge or sock) which makes the sound (maybe?) not so strong on the bass reflex/bass alignment and more like more extended (BR/closed box). Compare. (Congrat) They look very nice.

[Geoffroy]

Well, I have done the "socks" test... It does indeed show that the vents in the front release some bass which interfere with the tweeter. It seems inherent to this design really. Not yet convinced about the medium though, my pc speakers do better on that aspect but off course lose all definition/spatial aspect.

This is the inside of the speakers, I have the feeling that there isn't enough acoustic foam (is it the right word?) and that the speakers were assembled without much work on the details (not surprised these are not expensive).

Pictures below...