Hey all,
I recently picked up a pair of B&W DM2a's and am in the middle of rehabbing them. Fortunately all drivers work, the crossover is in fine shape with no EC's, and the cabinets are coming along nicely.
Where I have run into trouble is that, yep you guessed it, some previous owner has messed with the T-line stuffing.
Basically once I removed the front baffle I found the cavity behind the woofer has had all the white fiberglass (?) completely removed. I also found the triple folded felt pad had been unfolded and stapled to the top and all the way down into the throat of the T-line partially blocking it.
Another area of concern is that the white fiberglass (?) in the bottom bend of the first fold of the T-line is very tightly packed. This makes me wonder if the PO took the existing teased stuffing behind the woofer and shoved it down into the bend, or if it was originally this tightly packed.
Some other points of interest: I also found strips of yellow fiberglass sheets (similar to what you would find in a pipe insulation wrap package) laid across the top of the stuffed bend of the T-line at both the inlet and outlet. Also, the rubberized open weave bat that is usually seen at the bottom edge of the front baffle board was also inserted down into the throat of the T-line.
Here's a cut away view of the cabinet and stuffing that shows the intent.
I can easily restore the folded felt mat back to the original intent.
I can also move the rubberized open weave batting back to its original position.
The Yellow fiberglass strips are probably not hurting anything.
Where I need assistance is with the following:
1. What is the original stuffing material behind the woofer?
2. What would be a suitable replacement for this material?
3. Is the 1st bend of the T-line supposed to be very tightly packed?
and
4. any other insights or recommendations are appreciated?
I will post more pics in the next couple posts.
I recently picked up a pair of B&W DM2a's and am in the middle of rehabbing them. Fortunately all drivers work, the crossover is in fine shape with no EC's, and the cabinets are coming along nicely.
Where I have run into trouble is that, yep you guessed it, some previous owner has messed with the T-line stuffing.
Basically once I removed the front baffle I found the cavity behind the woofer has had all the white fiberglass (?) completely removed. I also found the triple folded felt pad had been unfolded and stapled to the top and all the way down into the throat of the T-line partially blocking it.
Another area of concern is that the white fiberglass (?) in the bottom bend of the first fold of the T-line is very tightly packed. This makes me wonder if the PO took the existing teased stuffing behind the woofer and shoved it down into the bend, or if it was originally this tightly packed.
Some other points of interest: I also found strips of yellow fiberglass sheets (similar to what you would find in a pipe insulation wrap package) laid across the top of the stuffed bend of the T-line at both the inlet and outlet. Also, the rubberized open weave bat that is usually seen at the bottom edge of the front baffle board was also inserted down into the throat of the T-line.
Here's a cut away view of the cabinet and stuffing that shows the intent.
I can easily restore the folded felt mat back to the original intent.
I can also move the rubberized open weave batting back to its original position.
The Yellow fiberglass strips are probably not hurting anything.
Where I need assistance is with the following:
1. What is the original stuffing material behind the woofer?
2. What would be a suitable replacement for this material?
3. Is the 1st bend of the T-line supposed to be very tightly packed?
and
4. any other insights or recommendations are appreciated?
I will post more pics in the next couple posts.
Here are the speakers as I found them after removing the baffle board...
This is the initial view.
This is a view where you can see the felt pad draped down into the throat of the T-line.
This is a shot down the throat showing the rubberized bat shoved into the opening.
Here after the bat is removed you can see the yellow fiberglass laying on top of the white fiberglass, and the felt mat running down and interfering with the throat opening (there is a brace that keeps it from continuing down the throat).
Here you can see with the yellow fiberglass strip removed and the white fiberglass tightly stuffed underneath.
This is the felt mat removed. You can see it still has the creases (memory folds) of being doubled up and triple folded to emulate what's in the cut away illustration in the 1st post. When I removed the felt mat I found it was stapled with very modern shiny staples haphazardly, and also had some upholstery tacks in only one of the speakers. All in all, this doesn't reflect the attention to detail the rest of the speakers had from the factory.
This is the initial view.
This is a view where you can see the felt pad draped down into the throat of the T-line.
This is a shot down the throat showing the rubberized bat shoved into the opening.
Here after the bat is removed you can see the yellow fiberglass laying on top of the white fiberglass, and the felt mat running down and interfering with the throat opening (there is a brace that keeps it from continuing down the throat).
Here you can see with the yellow fiberglass strip removed and the white fiberglass tightly stuffed underneath.
This is the felt mat removed. You can see it still has the creases (memory folds) of being doubled up and triple folded to emulate what's in the cut away illustration in the 1st post. When I removed the felt mat I found it was stapled with very modern shiny staples haphazardly, and also had some upholstery tacks in only one of the speakers. All in all, this doesn't reflect the attention to detail the rest of the speakers had from the factory.
Here are a bunch of random pics of the same speakers I found on the internet (not mine) that shows the original stuffing as best as I could search out.
This is what it should look like when removing the baffle.
It's a little hard to make out, but you can just see the folded felt mat over the crossover. Also notice the rubberized open weave bat across the exit of the T-line.
Close up of the white fiberglass like stuffing behind the woofer. This is the same material in the bottom of the 1st bend of the T-line. I took a lighter to a tuft of it and it doesn't smell like burnt plastic or hair. It does just barely catch fire or singe. It is very fine gossamer like substance. I am pretty sure it's a form of fiberglass, but not 100%.
Here you can see someone pulling out the folded felt mat.
Another view of the folded mat being pulled out.
Another view of what front should look like.
Another view of the white stuffing.
This is what it should look like when removing the baffle.
It's a little hard to make out, but you can just see the folded felt mat over the crossover. Also notice the rubberized open weave bat across the exit of the T-line.
Close up of the white fiberglass like stuffing behind the woofer. This is the same material in the bottom of the 1st bend of the T-line. I took a lighter to a tuft of it and it doesn't smell like burnt plastic or hair. It does just barely catch fire or singe. It is very fine gossamer like substance. I am pretty sure it's a form of fiberglass, but not 100%.
Here you can see someone pulling out the folded felt mat.
Another view of the folded mat being pulled out.
Another view of what front should look like.
Another view of the white stuffing.
Here are some additional pics. These are more of the outer condition and start of the rehab process.
Here's what they looked like when I got them.
1st thing I did was replace the gross grill cloth with a loose open weave Flax linen cloth.
Without grills.
Close up of one speaker.
The finish was some sort of tinted opaque lacquer.
Got the woofers all cleaned and surrounds treated. Also, some paste wax really shined up the coating on the cones.
Here's the 1st coat of oil after being stripped, veneer repairs, and sanded. Such lovely Walnut veneer.
Even the backs are very nicely veneered!
Close up of side of one of the speakers.
Here's what they looked like when I got them.
1st thing I did was replace the gross grill cloth with a loose open weave Flax linen cloth.
Without grills.
Close up of one speaker.
The finish was some sort of tinted opaque lacquer.
Got the woofers all cleaned and surrounds treated. Also, some paste wax really shined up the coating on the cones.
Here's the 1st coat of oil after being stripped, veneer repairs, and sanded. Such lovely Walnut veneer.
Even the backs are very nicely veneered!
Close up of side of one of the speakers.
The idea of transmission lines is some heavy damping of airflow in the taper:
Thanks to planet10 for an IMF image. Notice the air can flow a bit. Not solid stuffing.
We have looked at the DM2A quite often:
B&W DM2A Speakers
Thanks to planet10 for an IMF image. Notice the air can flow a bit. Not solid stuffing.
We have looked at the DM2A quite often:
B&W DM2A Speakers