Hifi!

[Superluminal 3841]

Anyone know anything about speakers?

Ive got a pair of inherited Mission 700S speakers for my hi-fi and one of them has developed a bit of a fuzzy reverberationy distortion.

I swapped them over to make sure it wasnt a connection problem to the amp but it stays with the particular speaker. They are knocking on close to 40 years old or so now and have never been cleaned / serviced (if thats a thing) Dont really want to scrap them as they have some sentimental value even though they were far from top of the range when new. If i open them up, apart from hoovering out any dead spiders is there anything I should be specifically looking for? Bearing in mind i have the understanding of electronics of a four year old.

[El Gecko 1426]

26 minutes ago, Superluminal said:

Anyone know anything about speakers?

Ive got a pair of inherited Mission 700S speakers for my hi-fi and one of them has developed a bit of a fuzzy reverberationy distortion.

I swapped them over to make sure it wasnt a connection problem to the amp but it stays with the particular speaker. They are knocking on close to 40 years old or so now and have never been cleaned / serviced (if thats a thing) Dont really want to scrap them as they have some sentimental value even though they were far from top of the range when new. If i open them up, apart from hoovering out any dead spiders is there anything I should be specifically looking for? Bearing in mind i have the understanding of electronics of a four year old.

Not familiar with those particular speakers, but if you can get inside the cabinets, check all the wiring at least, the connections between speakers and plugs, etc. The plugs and other things can loosen over time (with many vibration cycles).

It could also be that the crossover or capacitor has blown, in which case you can try to find a new crossover (usually a simple PCB with capacitors/resistors/inducers). If you have a multimeter, you can check if it still shows 8 ohms at the terminals (unplugged from any power source). If it's showing much more or less than 8 ohms, that could be an indication there's something wonky with the crossover.

And lastly but hopefully not, there could be something physically wrong with one of the speaker drivers themselves. A voice coil could have a loose wire, or the glue/foam is coming off the cone allowing odd movements.

So, hard to say for sure without taking it apart and doing some testing.

[Superluminal 3841]

3 hours ago, El Gecko said:

capacitors

resistors

inducers

multimeter

ohms

crossover

These words suggest to me i need to "get a man in" who knows what these things are.

I disconnected the wires off of the red and black posts which were caked in dust and cleaned them with some IPA - this didnt make any difference sadly.

So i undid the screws and took the back off.

These must be the Ohms you were referring to. They have wires which go into some foam.

Inside the foam is the big and small speakers.

The rubbery ring between the outer metal ring and the middle bit of the speaker has lots of cracks in.

I assume its just perished with age as i dont play it very loudly as im in a terrace with neighbours and this is likely whats causing the poor sound quality?

[Superluminal 3841]

I desoldered the wires on it to remove the bigger speaker. It looks like this from the front.

The part with the cracks turns to dust when you touch it.

Id like to replace these if I can - any suggestions on what to look for to replace them with if they arent going to be repairable?

[El Gecko 1426]

1 hour ago, Superluminal said:

The rubbery ring between the outer metal ring and the middle bit of the speaker has lots of cracks in.

I assume its just perished with age as i dont play it very loudly as im in a terrace with neighbours and this is likely whats causing the poor sound quality?

That right there is almost certainly the problem! I'm not sure how well those "refoam" kits work, or if they're available for your model, but I can say from experience that's probably it. The blue cylinder thing attached to the circuit board is a capacitor, and that's usually what blows (you would see the endcaps bursting but thankfully yours look square on still).

If you're curious, the circuit board itself is the "crossover" which just sends the correct signal to the correct speaker driver (high frequencies for the tweeter, low for the woofer). The crossover also helps bring out the midrange frequencies, which tend to be lacking in 2-way speakers like this (2-way=two speaker drivers in each cabinet, one tweeter and one woofer).

Having been the recipient of numerous broken speakers over the years, I've still never tried a refoam on any of them. Rewiring, replacing electronics, replacing broken speaker drivers for different ones, yes. But never a refoam. If those were mine, I would probably just look around for another pair of 8" woofer drivers to bolt in there (I think 8" is the right size but best to measure). All the rest of it looks to be in good shape.

[Superluminal 3841]

Thanks mate - so is "woofer driver" the search term i need to be looking for for this assembly?

I see the 8ohms bit is also printed on these - is there anything else I should look out for? Im not a big hifi buff so half decent sound quality is enough for playing my charity shop vinyl and 90s death metal cds.

Cheers!

[El Gecko 1426]

4 minutes ago, Superluminal said:

Thanks mate - so is "woofer driver" the search term i need to be looking for for this assembly?

I see the 8ohms bit is also printed on these - is there anything else I should look out for? Im not a big hifi buff so half decent sound quality is enough for playing my charity shop vinyl and 90s death metal cds.

Cheers!

Yes, I would search your particular model like "mission 700s woofer replacement" or similar, to see if anyone has done any swaps before. At least maybe you can find the correct size you need (I forget if it's measured by the diameter of the flange or the diameter of the bolt holes) and the ohms. There's no markings on your woofer that I can see, but since the tweeter and box are both 8ohm, it's a safe bet that the woofer is, too. Also make sure it's not a "subwoofer" since those are tuned for even lower frequencies and wouldn't sound right in this system.

[Superluminal 3841]

Legend! Thank you.

[Superluminal 3841]

I had a look at the refoaming process - dont very much like the look of attempting that!!!

Found these;

https://willys-hifi.com/products/monacor-sph-210-bass-mid-speaker#:~:text=Monacor SPH-210. Good replacement for Mission 700. This,general replacement for 2 or 3 way systems.

Theyre located in Saaarfff End which is just down the road from where I work too.

[El Gecko 1426]

6 hours ago, Superluminal said:

I had a look at the refoaming process - dont very much like the look of attempting that!!!

Found these;

https://willys-hifi.com/products/monacor-sph-210-bass-mid-speaker#:~:text=Monacor SPH-210. Good replacement for Mission 700. This,general replacement for 2 or 3 way systems.

Theyre located in Saaarfff End which is just down the road from where I work too.

Hah, that's pretty much where I ended up with refoaming too... just too messy and unpredictable for the cost. If the single review on that page is to be believed, then those should work perfect. Maybe pop down there on your lunch break and inquire with a salesperson? Bring your woofer along to do a size check in the store too. Nothing worse than buying something that doesn't fit!

[Superluminal 3841]

Two new Monocor SPH210 speakers and a box of albino wotsits from Willys Hifi (tenuous Tamiya link) - Huzzah!! Time to get me soldering iron on.

[Superluminal 3841]

Maximum success!

My neighbours are currently enjoying Bolt Thrower.

Is there likely to be any value in these or are they bin fodder?

[topforcein 1764]

On 1/14/2023 at 12:22 PM, Superluminal said:

 

Is there likely to be any value in these or are they bin fodder?

tbh i would have re-foamed them its really easy to do infact the hardest part is getting the old foam of the cage and cone 

i have done a load with my last lot being 4 15" subs 

and these will be going up for sale soon as i dont need them know even though i was trying to buy these from my mate for 20 years and he finally gave in last year due to the foams and his other half i even said i would give him a pair back and he could put them in his snooker room but i think he dont want to upset the other half i would love to keep them but i already have a pair of realistic mach 2's that i like better

shame i aint been on here for a long time as i would have offered to re foam them for you instead of replaceing them 

 

[Superluminal 3841]

1 hour ago, topforcein said:

tbh i would have re-foamed them its really easy to do infact the hardest part is getting the old foam of the cage and cone

I watched a couple of youtube tutorials and I sort of lost my bottle when he used a scalpel blade to start cutting out the dome piece in the middle of the cone. I didnt think i would have ever made a neat enough job of that to be able to fix them back properly.

On the one in your photo with the pegs around it is that drying out? Looks like youve done a great job of those.

[topforcein 1764]

19 hours ago, Superluminal said:

I watched a couple of youtube tutorials and I sort of lost my bottle when he used a scalpel blade to start cutting out the dome piece in the middle of the cone. I didnt think i would have ever made a neat enough job of that to be able to fix them back properly.

On the one in your photo with the pegs around it is that drying out? Looks like youve done a great job of those.

yeah i know what you mean with the dust cone you can take that of to shim the voice coil to keep it central so it won't rub but you dont need to do that tbh i did the first time but since then i dont bother with that anymore

i also watched u-tube video's from the place where i brought my first foams from (springfield speakers repairs) in the U.S.A but i tryed to order the foams for the memorex's bu they wont ship outside the U.S.A anymore

and yes the one with the pegs all round it is to keep it down whilst drying as the foam tends to curl up so i found this method i use a great aid but for when its time to glue it on the cone you have to keep pushing it down until it stays flat. i have had glue bleed on my first time but on the 4 i recently did and the ones before that i was lucky with no bleed.

the ones you took out will still work and prob sound better than what you have replaced them with but if your happy with the result 

[El Gecko 1426]

On 1/14/2023 at 7:22 AM, Superluminal said:

Maximum success!

My neighbours are currently enjoying Bolt Thrower.

No guts, no glory! (Bolt Thrower/Tamiya Frog reference)

[Superluminal 3841]

31 minutes ago, El Gecko said:

No guts, no glory! (Bolt Thrower/Tamiya Frog reference)

I'd missed that one! Great track and as an album Mercenary tends to not get the credit it deserves

[Superluminal 3841]

55 minutes ago, topforcein said:

the ones you took out will still work and prob sound better than what you have replaced them with but if your happy with the result 

Thats why I thought it a shame to get rid of them and dont want to bin them. I'm happy to cover all costs inc' time if you fancy an attempt at repairing them? Otherwise they will just likely end up in the loft.

[topforcein 1764]

On 1/17/2023 at 5:03 PM, Superluminal said:

Thats why I thought it a shame to get rid of them and dont want to bin them. I'm happy to cover all costs inc' time if you fancy an attempt at repairing them? Otherwise they will just likely end up in the loft.

i dont mind having a go at them tbh first of spread you fingers over the cone and gentle push done on it and see if you feel/hear any rubbing from the voice coil  if thats ok search the size of the replacement foams / or rubber ones if you can get them 

this is the glue i use...https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2334524.m570.l1311&_nkw=t7000+black+glue&_sacat=0&LH_TitleDesc=0&_odkw=T7000+Black+Rubber+Surrounds+Repairs+Spare+Foam&_osacat=0

this is for rubber surrounds....https://www.ebay.co.uk/itm/402905366964?_trkparms=amclksrc%3DITM%26aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D245061%26meid%3D0ef3ee661b4f4961a39b3bc3bb888b53%26pid%3D101112%26rk%3D2%26rkt%3D12%26sd%3D163606714080%26itm%3D402905366964%26pmt%3D0%26noa%3D1%26pg%3D2047675%26algv%3DDefaultOrganicWebV9BertRefreshRanker%26brand%3DUnbranded&_trksid=p2047675.c101112.m2109

here is the foam surrounds some come with the glue also ....https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2334524.m570.l1313&_nkw=foam+speaker+surround+repair&_sacat=0&LH_TitleDesc=0&_odkw=foam+Surrounds+Repairs+Spare+Foam&_osacat=0

[FoxShot 280]

I recently re-glued the cone on the Sub in my car. I'd had a vibration, and when I had the unit out, noticed the box had come unfixed, so took the speaker out to fix it. Then i noticed part the rubber wasn't glued down. Full rebuild! 1st attempt ever.

All glue removed, and raised ready for application. That's the glue I used.

Securely "clamped" in place.

Rather than loose wire, I fitted these. 

Filled some of the void with something like K-poc. The filling of a pillow loosely put inside to eliminate standing waves.

Sounds so much better.

Now, I've got to figure out why the amp isn't amplifying one channel input!! Its an Alpine MRD M Series