Naim DBL Woofer

Hi does anyone know the exact model of the ATC woofer used in the DBL? I did some searching and 2 models came out:

  1. SB100/375SC
  2. SB75/375SC


Hi, i dont think the DBL had the standard atc 15 inch woofer, they used a modified version of it. I wish it was just a standard woofer so that I dont have to send the originals from Australia when they need new foam surrounds. I think there is some air vent around the back near the magnet to aid cooling.

Thanks Mario.
All the ATC 15” woofers have air vents. Naim added a net I guess is to prevent the foam/dirt from getting into the voice coil.

OK thank you for that info, maybe the 15 inch drive is similar enough to just replace it with the standard ATC one, they look identical from the outside. More importantly, the newer SL variants will be better. Any comment from naim on this? I’d buy a set if they were similar enough. There may be some difference though as ATC use them in a reflex cabinet and the DBL’s are sealed. I wonder if ATC could be persuaded to make some exact DBL spares so that DBL owners could just buy a set?

The difference between these two drivers are that the 75 has a voice coil diameter of 75mm and the 100 has 100mm diameter of the voice coil.

Should be fairly easy to measure your self. Normally it says on the sticken on the magnet also.

I contacted ATC when I thought I had an issue with my DBL woofer and they said the DBL driver is: ATC SB75-375 SC


Thanks guys. So it’s confirmed SB75-375SC.

I have had my DBLs since 1998. I have replaced the woofers once, but could not find the receipt and model number. I may be biased, but I recalled I could not get the same bass performance as the original woofer that came with the DBLs, so there may be something that naim did to the woofers. I was willing to live with the trade offs as my original woofer has been refoamed before and beginning to show its age.

Do you really need to replace the woofers?
A reconing kit is what you need.

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AFAIK the modification that Naim make to the COTS ATC driver for use in the DBL is to remove the label off the back of the magnet and glue on a very short length of waste pipe and a (concave) mesh.

I imagine if you procured new drivers from ATC you could transfer the Naim “subassembly” from your existing ones. Of course you’d need to be careful to not get any crap in the voicecoil gap.



This is really useful info.
I wonder if @NeilS, could just confirm if this is the only real difference in the woofer used in the DBL, compared to the normal ATC one.
I dread the thought of sending 15 inch drivers to the UK for refoaming, but its inevitability going to need to happen one day. If I could just buy brand new replacements, it would be a worry off my mind. Unlike my cds3, which is still working well, there may be hope for my all time favourite speakers.

If you want to attract the attention of another forum member, you would have to put @ immediately before their name.

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thanks JimDog, didn’t know this, hope it works.

I think that was the only mod we did to them.



Great thank you very much Neil, any idea as to why it was done? To keep things out of the voice coil, airflow?

Now that I don’t know - I’ll see if I can find out.


Well, my enquiries have hit a dead end. Roy George would the person to ask, but I’m not in touch with him these days.


Ok no worries, you have provided some good info.
Thank you.

I’d check with ATC too. After all they did a modification to their production line of products and likely have documentation left on it.

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SB75-375SC is not in production any longer. Reconing of existing woofer by ATC or reworking the PXO and fitting an alternative woofer are the only options.

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Thanks guys for all the suggestions. I managed to get the woofers refoam. In the process I also took the opportunity to replace the foam inside the enclosures. Now to run in the new surrounds.


Had mine refoamed last year by ATC. Took about a month for them to sound right. Torque went off a bit within the Month. A quick retorque and they were sounding magnificent!