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Boston Acoustics T930 Series II Woofer Replacement

M

Mike Czech

New Member
Hello all,
Have used this site as a non-member for years. Now that I am a member, would like some input on a possible replacement question.

Picked up a pair of Boston Acoustics T930 Series II for free. The woofers surrounds were redone incorrectly and I do have a speaker repair outfit nearby that can fix them.

Should I instead replace them with a better replacement woofer with similar specifications for resonant frequency, frequency response, and sealed enclosure size?
 
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IMO no, have them refoamed with the correct surrounds (assuming the drivers are okay otherwise).

Bought a new pair of T1030s way back when they were being discontinued.
Wish I would have kept them when I got the itch to try something new years later.
 
I agree that the original woofers are your best bet. That is the way the speakers were designed.

What do you mean by "redone incorrectly"? Wrong surrounds? Off center? Sloppy job? Does the voice coil rub?
 
If you are the least bit handy, replacing a surround is pretty easy. Lots of info here and on line to aid you. Post some pics so we can see how botched the job was and advise better.
 
Dropped off woofers today with Midwest Speaker Repair. They performed a visual inspection, mechanical interference inspection and applied a test signal to each unit using a frequency sweep covering the woofers normal response. The visual inspection confirmed a poor surround replacement job, poor alignment of the cone and surround and voice coil rubbing in one the units due to poor alignment. Fortunately no damage to voice coil and they will perform a correct replacement of surrounds. I should be able to pick up the Friday after Thanksgiving.
 
They also stated that using the original Boston Acoustics woofers was the best choice. I did inquire about rebuilding the cross overs and they do have the high quality capacitors and inductors in stock to perform this task. I will be removing the old crossovers and prepare them for the upgraded components.
Thanks again for all your encouragement to restore the 930s to their former glory using original components.
 
Picked up the repaired woofers today from Midwest Speaker Repair. They look great and the gentlman that replaced the surrounds demonstrated each woofers performance with their test equipment.

I connected and installed them in the cabinets. The gasket seal was still in perfect condition so they should perform correctly. I did inspect the crossovers and they look to be in good condition. Tomorrow I will place them in my listening room and run them in for 24 to 48 hours before reporting on their sound.
 
Played several CDs for about two hours. The woofers and midrange are fine. I think the tweeters have a lower output than what I expect. The sound was smooth overall, but slightly muted in higher frequencies.

This could be due to old ferrofluid. Will consult with Midwest Speaker Repair to see if they suggest replacing the fluid.
 
The weakest link in the early Boston speakers were the woofers. So once you get them fixed don't push them to hard as OEM woofers are no longer available.
 
I finally decided to replace the midrange surrounds on the BA T930 series II. I took them to Midwest Speaker Repair and they are ready to be picked up. In the meantime time I did rebuild the crossovers with new NP capacitors and a solen one for the tweeter. I couldn't find a schematic for this model, so I drew one up from the crossover board.
The crossover used point to point wiring, so i had to hot glue the new components into the same positions as those being replaced. I measured all the inductors and resistors and they still met specs.
Boston Acoustics T930 series II crossover.jpg
 
Mike Czech said:
Sorry, forgot to mention that updated the NP capacitors with ones rated for 100V and the solen was rated for 250V.
Click to expand...
Installed the midranges today after Midwest Speaker Repair replaced the surrounds.
1st test of the rebuilt crossovers and repaired midrange units.
Popped Agnes Obel, Citizen of Glass in the CD player.
OMG! Recording studio quality issued forth! I am totally blown away. Bass tight and impactful, Midrange smooth as a babies bottom, Highs silky and non fatiguing at an volume.
 
Attaching the pics of the Boston Accustics T930 II crossovers.
Thanks for the circuit schamstics.
 

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