DBL refurbishment

I sort of bought DBLs by accident. I had seen a pair sell on ebay for under £3k, in black, recent full driver replacement and described as mint. Unfortunately they were in south east, no boxes and thus required a van, a ferry crossing and a thousand mile drive to collect so I held fire. But the thought was there that liquidating my SL2s would have gone a long way towards funding those.

A few weeks later I popped into my local dealer, purely a social call as I was in the area at the time (arguably the best cobbler in NI is a few doors down). Mentioned the ebay DBLs and how I might have sprung had they been closer to home. He responded that he might know of a pair and he’d look into it. Several weeks later, after a holiday, I got a call that indeed there was a pair available locally. I expressed interest and inquired about auditioning/viewing them. After several calls it was clear that the seller had already purchased new speakers and the DBLs were boxed. I agreed a price, contingent on validating their condition.

There followed a period of frantic diy where I went above and beyond a request to paint the kitchen ceiling and instead build a whole new fitted kitchen, had a Rangemaster cooker and hood installed, and then announced that I might be getting some new speakers. I did use the word “bigger” though it is just possible I was breathing in at the time and it didn’t come across very distinctly.

One day a van arrived. Two men unloaded four large boxes and two enormous boxes into my home office/mancave. Fortunately looks can'y kill.

Waited for the dust to settle and unpacked. The condition of the speakers was far mint. Cosmetically I’d have described them as 7/10. Not such an issue as they are out of the way in my office but obviously has an effect on price. The bass driver surrounds were shot, one having a section of 3” missing. The pads on the bass boxes were perforated. The underside of the treble boxes were deeply gouged, 5+mm in depth. The spikes supporting the treble boxes were bent. The Velcro on the one bass box that had been bagged was reasonable, the other three had been packed without being bagged and thus the Velcro had been peeled back at the corners. Annoyingly the three bags were present in the bottom of one of the boxes. In packing the crossover had been resting on one of the gaskets and had produced a notch on both sides of it (over a few weeks these sprang back out). A section of the lower band on the tweeter support frame had been hacksawed out. Have been unable to determine why someone would do that, my theory being that it makes it possible to reach in and unplug the feed to the bass cabinet whilst it’s in situ.

On the plus side midrange and tweeters had been replaced approx. five years ago, though looks like they were done by someone wearing boxing gloves. Grilles were new USA sourced ones and looked the part.

I slept on it, did some calculations and made an offer based on what I reckoned it would cost me to restore them and what they would be worth in that restored state. After a few weeks of contemplation the seller agreed to my offer and the work began. I’ll focus here on the tweeter box restoration and update on the bass boxes as that’s still ongoing.

First off was the filling. As I said they were quite deeply gouged and I had to remove a lot of loose material to get back to a firm foundation. I initially used a box cutter to cut in and then finished off with a pointed grinding tool in a “dremel” (lidl equivalent) to smooth off the surface.

 

Filled the surface and sanded back to flat with a sanding block and 120 grit.

And filled.

Next up the spikes. As you can see from the photo they were bent. At least 6 of the 8 were visibly bent.

 

Approached Naim about replacements but they’re no longer stocked so I had some new ones made from M4 Stainless Steel. Got a dozen so as to have a few spares. 

 

Glued nuts onto the spikes using a suitable adhesive.

 

Needed to get the correct height for the spikes so measured the height of the tweeter box and then set the starting position for the spikes to that distance down from the top of the cabinet. Needed a few tweaks to get them aligned and level but was relatively straightforward. Can clearly see the trapezium cutout in the tweeter support frame.

 

Not planning any major cosmetic work at his stage, just want to get them running but I did have a roll of double sided tape kicking around the office so I carefully cleaned under the loose corners of the Velcro and stuck them down. Actually made a significant improvement to the appearance.

 

Will follow up on the bass boxes later, currently waiting on new aluminium pads to complete that. Meanwhile current state...

Regards,

 

Willy.

Original Post

Wow Wiily, best post I have seen in zonks. So glad you posted this, a great read and restoring these beasts will be so rewarding!

Any pair of DBL's would be worth restoring, all 149 pairs of them! Most work would be doable as long as the mids are in good shape. Thank God ATC service the base cones and the tweeters are available.

 

I often wondered if you could pop a different driver in for the mid if they were completely knackered, B110's maybe??

 

Any way, great that your drivers are all good, looks like these will pretty much be performing back to new when finished.

 

Please continue the posts, especially on the pads and gaskets!

 

Take your time and enjoy the process!

 

Mario.

 

 

Tonym put me in contact with Jon Honeyball who kindly contacted Naim and has confirmed that the DBL gasket kit contains new pads (as well as the gaskets and sealant) and is believed to be in stock. With the part number Jon supplied, my dealer has ordered the kit. All I have to do now is wait. Not really my forte.

Regards,

Willy. 

Well done so far Willy.  Hopefully the hacksaw work won't impair performance to any great degree.  DBLs are definitely worth the trouble and I'm sure they'll come up looking great.  I'm looking forward to reading about how you freshen up the black ash finish - I've read conflicting opinion on this.  Some say jet black ink, others black dye (which can sometimes come out blue/grey). My black ash Kans in my office could do with some tlc on the finish...

Mario, the Naim mid driver used in the DBL actually does use a B110 basket - IIRC Naim bought up the last stocks of them from KEF many years back - however, the driver itself is rather different and is a true midrange.  IIRC it's only shared with the NBL.

Fortunately when fully assembled the worst of the cosmetic wear and tear is on "hidden" edges and surfaces.  Around the midrange units is a bit messy where it's been touched up with a marker pen. The tweeter plates are also mismatched, one being gloss and one satin finish, however the company who made the spikes for me have a CNC punch so i may commission new tweeter plates if I can figure out the material spec (anyone know what they're made of?). 

I'm not planning to "tart them up" in the short term, but when I do, I know of a friend of a friend who does furniture restoration, and is local, so I'll start with getting him over to cast an eye over them. Hopefully he'll have a better idea on how best to proceed. I had black Briks for many years and am only too aware how difficult it is to address defects without making them even more obvious. In the longer term it's not inconceivable that I could strip them completely and get a total respray.  Then again, considering my age, and and ever declining sight........I could just listen without my glasses.

Regards,

 

Willy.

Marksnaim posted:

Really interesting thread here Willy and good luck with the refurb. Any longer term plans for these, active maybe? BTW Falcon Acoustics make a replacement for the B110 midrange which works very well. I have them in my Briks.

I'm a big fan of active. My SL2s were active, as were my IBLs before that so it's only a matter of time, and bank balance recovering from the preemptive quid pro quo of the kitchen upgrade.

Regards,

 

Willy.

Willy 

once you get these up and running you will realise you've probably bought your last pair of speakers 

i had active briks for years until last year when I got the dibbles in, the difference is night and day especially the mid range which surprised me, I was looking at that 15 inch bass driver and expecting to be blown away by it

i like most people here will recommend you go active 

6 135's a snaxo 362 and supercap should be on your shopping list now 

lyndon

 

Drewy posted:

Great thread. Thanks for sharing and keep the updates coming. 

How can people be so careless with these things? I work hard to afford my hifi and would never let it get in that state. 

Agreed on both points. Great thread and it's hard to understand how anyone could be so careless with such a costly pair of loudspeakers. I guess it is possible that they had been a demo pair at some time , which had been set up and transported several times in their life. But that probably wouldn't explain cutting through the cross-brace.

If they were mine I think I'd have to go for the full refurb and have the cabinets properly refinished and the cross-brace replaced etc. It's good to know that there is a replacement available for the mid- range driver. 

Willy, please keep us posted as the project progresses. 

ICE KACHANG

you will need to remove the sealant between the bass driver cabinet and the lower cabinet 

its pretty much straight forward mastic, most of it will peel off, the last bits that are left can be removed with a Stanley knife and or soapy water

obviously this will need re instating

lyndon

 

That's right Clive, sorry if I caused confusion, the B110 is NOT a suitable replacement driver for the DBL mid, but if mine were knackered and naim could not help, and if no one could re-cone the old ones, or fix the voice coil, at least the B110 would get sound out of them again. I think Falcon Acoustics may make a paper version of the B110, which may be a little closer again, but still not a proper replacement. Just handy that they could just pop in as the basket is the same (thanks Richard). Mind you, the mids do take some bashing, but I have heard a friends NBL mids get damaged (apparently too much alcohol and a stupidly loud CD playback session) . There are some repairers out there that can re-cone them, but its a fiddly job (find matching voice coil, rubber surround, glue etc). Wish naim could supply a recone kit.

 

Mario.

lyndon posted:

ICE KACHANG

you will need to remove the sealant between the bass driver cabinet and the lower cabinet 

its pretty much straight forward mastic, most of it will peel off, the last bits that are left can be removed with a Stanley knife and or soapy water

obviously this will need re instating

lyndon

 

Thanks.  They were originally built by Doug from Naim who I believe used 'fairly liquid' on the gasket.  I was told that this meant that I should be able to remove the bass boxes without destroying the seal.
 

ice kachang posted:

I'm going to be dismantling and boxing up my DBLs in the next couple of weeks.

Any tips on things to be careful of or to look out for.  I have all the packaging but need to work out what goes where.

There are reasonably comprehensive instructions in the Naim owners manual for unpacking, simply reverse them. From my own experience I would also suggest; caution in boxing the crossovers so that they cannot shift and damage the gaskets, and bagging the bass and treble boxes before inserting them into their packing (to prevent damage to the velcro).

Oh, and unless you are substantially larger, stronger and younger than me then get someone to assist. (At last a use for the exploding sausage, as a metaphor for the state of my lower back!).

Regards,

Willy.

PS I downloaded the manual from Manualslib website.

Clive B posted:
Drewy posted:

Great thread. Thanks for sharing and keep the updates coming. 

How can people be so careless with these things? I work hard to afford my hifi and would never let it get in that state. 

Agreed on both points. Great thread and it's hard to understand how anyone could be so careless with such a costly pair of loudspeakers. I guess it is possible that they had been a demo pair at some time , which had been set up and transported several times in their life. But that probably wouldn't explain cutting through the cross-brace.

If they were mine I think I'd have to go for the full refurb and have the cabinets properly refinished and the cross-brace replaced etc. It's good to know that there is a replacement available for the mid- range driver. 

Willy, please keep us posted as the project progresses. 

I also strongly suspect they were a demo pair. Even if not being moved the cutout would make it possible to change from passive to active without disturbing the bass box. 

The decor of my office is long overdue for a refresh and when that happens the DBLs will need to be removed, along with everything else, as the floor needs refinishing. That is when I'm notionally planning to do a cosmetic refresh and get a section welded into the tweeter box support frame.

Regards,

Willy.

Worth mentioning the Fairy liquid dodge Willy, in case you didn't know. Before applying the silicone to the bottom box, smear a thin layer of the stuff on this and on the underside of the bass box, and allow it to dry. Makes it much easier if you need to seperate the boxes in the future.

tonym posted:

Worth mentioning the Fairy liquid dodge Willy, in case you didn't know. Before applying the silicone to the bottom box, smear a thin layer of the stuff on this and on the underside of the bass box, and allow it to dry. Makes it much easier if you need to seperate the boxes in the future.

Was aware of that but not sure if it was only on the gasket or on the bottom box as well. Thanks for clarifying that it's both.

Regards,

Willy.

Part 2. Bass Drivers.

As mentioned earlier the bass drivers were showing their age. Surrounds on both were “delicate” a large hole in one of them.

 

As can be seen Naim have modified the ATC drivers with a bit of waste pipe and a little grill at the back.

Ordered up shipping boxes from ATC and modified them with a circular cutout in the packing material to accommodate Naim’s modification to the driver. For good measure I set a piece of cardboard into the hole I cut in the packaging so that no loose polystyrene would get into the grill at the back of the drive unit.

ATC turned the drive units around in about a week. Really a very pleasant company to deal with. The drive units came back looking good as new, they even made up some bespoke Naim Audio labels for them!

The reconed drive units were not installed until after I’d refurbished their cabinets (will come back to that later). Torqued to the requisite 3.6Nm. Left for about a week and then retorqued (fractional movement on most of the bolts).

Finally a sliver of silicon around the periphery to seal them off.

So there we have two rebuilt bass boxes with reconed drivers.

Regards,

 

Willy.

Part 3. Gasket Kit.

First off was the preparation, filling and sanding to take the new aluminium pads.

Next up was positioning the pads. I’m sure this could be done just visually but I may have had too much time available when removing the old ones and I’d made a template of their locations.

For a half blind old codger such as myself peeling the backing paper off the pads was arguably the most difficult part of this whole operation but I got there eventually and positioned them using my template. I’d pre-cleaned the surface of dust but even so the adhesive on the pads is…….I now understand why they use staples as well.

I know a lot of folks have struggled with getting the staples in. In anticipation of this I’d conducted a set of experiments with the old pads and determined that this stapler was up to the task.

I got this one for free (along with a sizeable collection of pre-digital opera and classical boxed sets) but they’re available new for under #30. Anyway it did the trick though just to be sure I gave the staples a wee tap with a hammer.

Next up the gaskets. The old ones came off relatively easily. Then cleaned the surface with Isopropyl. Once again I made a template to assist with getting the gasket in the correct place. Stuck down the back edge first and then removed the remainder of the backing paper and stuck the whole thing down.

Did the spacer/slide-out/press bit and then applied the silicon, having first applied Fairy Liquid to both surfaces and letting it dry. Might have been a bit generous, more 6-7 than 5-6mm. Probably should have practised more. I’ll do better next time.

Installed bass boxes and removed spacers. Easier than I’d expected as they seemed to locate relatively easily into the indents.

Stuck the top boxes back, et voila.

Now the hard bit. Waiting 24hrs for the silicon to set. I'm off to the beach with the dog and I've got a beer in the fridge to follow that. That's the first 2 hours taken care of.

Willy.

Fascinating to follow a labour of love...

If they work as well as my DBL's you will be in for a treat. Seeing a pair of Kans reminds me that I used to think Isobariks were like Kans with bass but in reality they are too slow to match Kans. I think you will find that DBL's really are a Kan replacement with all the speed and insight they can give you.

Richard Dane posted:

Mario, the Naim mid driver used in the DBL actually does use a B110 basket - IIRC Naim bought up the last stocks of them from KEF many years back - however, the driver itself is rather different and is a true midrange.  IIRC it's only shared with the NBL.

Richard - quick question. Is the DBL/ NBL mid driver closely related to the IBL bass (!) driver. They look very similar although i seem to recall the IBL driver was maybe Elac / Mordaunt Short sourced between the Mk 1 / 2 models?

James

Wow Willy, such a great thread, really enjoyable to read details and view pics. I'm printing the whole thread off and keeping it with my DBL manual. You have done it all so well. Be sure to check that the spikes on the very bottom of the cabinets have no flat spots. DBLs tend to get pushed around to position them correctly and if its along a concrete floor, the weight of the speaker easily flattens the tip of the spike. Spares are readily available from naim, at least they were about a year ago, but they are different to NBL spikes. NBL spikes are long and pointy but DBL spikes have a shorter tip profile to deal with the weight. ATC seem to have done an outstanding job.

 

Great work, you are really going to enjoy the fruits of your labour.

 

Regards,

 

Mario.

Hungryhalibut posted:

When Jason from Naim set up my SBLs once, he said there was no need to wait for the silicone to set and started them playing straight away. 

The practice run of silicone seems thoroughly cured so I suspect you may be right. Trouble is I'm now committed to other chores for the remainder of the afternoon so it's going to be this evening before kick off. Bugger.

Willy.

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