Mordaunt Short MS45Ti Series II

[chlorofille]

Hi all,

I purchased a Mordaunt Short MS45Ti speaker pair in a garage sale for $100. The tweeter is a 3/4'' Titanium dome, and paper bass drivers possibly in a 2.5way config. They are in excellent condition but when hooked up to my system, the bass is dreadfully lacking. For a speaker that has two 8'' speakers per side, this is rather unusual.

According to the manual, the speakers have an in built Positec protection. Maybe the protection is faulty and thus, cutting power to the bass drivers?
I've never had these cranked up loud, just a very moderate listening session <75dB. Might think of bypassing the Positec protection.

Anyone own these speakers ?

[The Saint]

Originally Posted by chlorofille

Hi all,

I purchased a Mordaunt Short MS45Ti speaker pair in a garage sale for $100. The tweeter is a 3/4'' Titanium dome, and paper bass drivers possibly in a 2.5way config. They are in excellent condition but when hooked up to my system, the bass is dreadfully lacking. For a speaker that has two 8'' speakers per side, this is rather unusual.

According to the manual, the speakers have an in built Positec protection. Maybe the protection is faulty and thus, cutting power to the bass drivers?
I've never had these cranked up loud, just a very moderate listening session <75dB. Might think of bypassing the Positec protection.

Anyone own these speakers ?

Hi

Nice buy BTW.

These were excellent speakers in their day, I have a pair of MS TI35s which
look very much the same only one 8" driver.
The bass from these should be very good. The poly switch in those could well
need replacing, WES components have these in stock.

Cheers

Anthony
Aussie Amplifiers

[chlorofille]

Thanks a lot Anthony!

[Salas]

Recently I had an MS speaker to see for fix, had an issue of volume drop as it was fed more power. It was the poly switches. I told my mate to bypass but he opted for bike lamps so to keep some protection as in the original.

[chlorofille]

Cool, any idea of the specs and wattage?

[Salas]

I asked him what he put in, he could not describe exactly as someone else did it for him, I would just use a 12V 20W for the TW and short the Positec for WFs. They looked like ceramic cap blue discs or NTC thermistor discs, shiny. When they age, especially after when they had been triggered before, they tend to duck power early. Now about the bass thing you mentioned, I hope its due to the Positec only since many things could be tired on an old speaker. I see the lower woofers look like they had been repaired on both cabs in your pic for instance.

[chlorofille]

I bypassed the Positec elements but no change in sound. Bass is still weak.
Upon closer inspection, the lower bass drivers seems to have been repaired, as there is evidence of dried glue. Half the surrounds on the midrange drivers have come loose and are flapping when I play some bass tracks. I can practically see through the edges of the cone as I gently pry the surrounds. The crossover is a 2.5 way, and the cabinet is made of chipboard, with a single brace in the middle. See attached pics.

[DrDyna]

I'd say the loose surround probably contributes to the loss of bass quite a bit. I'd probably try to glue it before even playing them anymore. I'd be nervous about voice coils coming into contact with motor structure if the alignment fails strongly enough.

[chlorofille]

Thanks. That's what I'll try. I've built a few speakers but know nothing of how to repair them....What kind of glue would be suitable?

[DrDyna]

Originally Posted by chlorofille

Thanks. That's what I'll try. I've built a few speakers but know nothing of how to repair them....What kind of glue would be suitable?

This would probably work well.

Speaker Repair Glue 1 oz. Bottle