But you could simply remake the original factory xo with top quality components and it would be better. Factory xo’s are rarely the best that can be done. Not just Naim but all manufacturers. They always cut costs somewhere in a xo… until you get very expensive.
no…the original xo did not addresses the native tipped responses of the drivers and had poor phase parameters (which did not allow very good imaging). You will not get that very linear response using the original design. My initial plan WAS to clone the original design with better parts but the speaker designer who did my xo was reluctant after measuring the original paxo…there IS however much room to improve the original parts though…look at the transfer function sweeps above…although they are OK into an 8 ohm resistive load, there are large resonance spikes into reactive loads…like drivers. This is mainly due to saturation of the ferrite cored inductors. Any new design at minimum should use air core inductors…with the LF and MR network using toroidal core inductors. And stay away from the $0.25 sand cast resistors. $5.00 Mills resistors will give very large improvement especially in the tweeter network. But I ended up trying both Duekund CAST resistors and Path Audio ones which were WAY better then the Mills…but cost $25-40 each. I also tried Ohmite resistors that I did not like… Midrange and tweeter caps should be very high quality film caps bypassed with 0.01uF Duelund ones. Like I said above, the one guy who owns both DBL and ESL57 now feels the DBLs are just as transparent and holographic as the 57s…which was NOT the case with the original PAXO.
Maybe one member who is following this thread who recently had this design fabricated would like to share his impressions?
Not sure if you saw my recent speaker build. These are the crossovers. Transparency is stunning. I am thinking of switching the resistors to path audio once I have the tweeter attenuation perfect and everything is well run in.
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The Path Audio will be a big step…you will notice a reduction of hash and a blacker background and an icrease of details and articulation. Try the 0.01 JDM bypass caps…about $50 each but the gains are not incremental.
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NB the tape wound foil and toroidal core inductors as well as the cylindrical black Duelund resistors in Stefanos xo. The parts cost here alone is probably in the order of $1500 between the two speakers. But the results…
There are $40,000 speakers out there that still use low end xo components but have a stunning piano black exterior.
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The DCR of toroidal inductors is 1-2 orders of magnitude lower than tape foil inductors. fir done speakers this will allow much greater damping on the bass drivers. We actually ran the model for the DBL using both inductors and there was little difference.
The guy with the 57s started off with less exotic component’s (picture) and incrementally replaced them all with higher spec…
Here is what he said on the first day with mid grade components-before any run in…since then they have very much further improved
"Hi Ron
I’ve had probably 6 or 7 hours in front of the DBLs now. So I thought I’d share some thoughts.
Earlier this afternoon before supper I played the Sheffield Drum Record - peaking at 92dB at my chair 10ft back which is atypical for me. I love the track by Ron Tutt. Previously it sounded a bit bloomy, not thick or heavy as such but a bit indistinct - almost as if the lower registers were echoing or doubling. Now it’s tight and sharp. This has helped with the perceived speed or tune playing. While he is kicking the pedal very hard he is also tapping the large cymbal. This rings true and the decay is as long as it should be. The cymbals sound like real metallic objects and not a messy fizz. The bass is quick, deft and powerful - easily felt in my chest.
I’m not hearing deeper bass (though this could easily be music dependant). But I am hearing better, more accurate bass. Plucked acoustic bass (I listen to a LOT of jazz) is now full of colour and character; little buzzes and scrapings on the frets are obvious. Equally electric bass, Miller, Pastorius etc is fast and really tight.
Because the bass and HF are now more accurate the midrange is really good. Vocals are projected forward and very intelligible where they were previously a foot or so back in the mix. The edges of the vocals are sweeter with less spit and sizzle. In the same range horn and sax players cut right through. Coltrane, Rollins, Pepper et al sound superb.
Also, as you mentioned, the image stays still better rather than wander around somewhat. I’m not big on imaging but it’s nice when it’s there.
I’ve used my usual 8TC from the NAP250. From the xover I’ve used 8TC to the bass and 4TC to the mid and HF - only because I don’t have enough 8TC for 4 runs. I’ll get some and swap it over. 8TC is markedly better "
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These xo’s are for the top section which is a 1st order (6”+8”) 2.5 way that is tuned to roll off at 80hz. The lows are handled by 12” downward firing woofers controlled by a 250w dsp plate amp.
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@Richard.Dane. Again, if details of the PAXO’s for DBL’s are being made available can you include me.
Thanks.
They look very business like. Is this something you put together with Ron’s layout or did you have someone make them for you?
the latter.
This is extremely high quality workmanship. If a DBL Statement ever was released, this is it. To be clear…it was my schematic that was fabricated by a third party.
Correct. For me, that was a given within the context of this discussion with Ron.
I heard the aftermarket crossovers… they were terrible. The factory crossovers were amazing.
Hi All
I cannot contact Guy of Pure Sound via message on t’Bay or via his mobile, which is not responding.
There seems to only be on his Bay site ‘NAIM DBL Loudspeaker Internal Foam Set (20 pcs)’ for £195.
This seems a tad excessive to replace my SL2 top box foam interiors.
I’m wondering whether anyone has any other ideas.
Thanks
Jim
Where did you get your replacement internal foam from, and what type and sizes was it?
Thanks
Jim
Please would members respect and abide by forum rules. Thank you.
Update - Pure Sound have responded on t’Bay.
I also opened up the top box and took out the two SL2 foam pads.
They are 25mm thick and about 11 x 14 cm in size.
Photos show that they were originally just forced in around the top wooden brace spur, not cut to fit.
I think I will try to replace them with cut to fit pieces.
Charlie, where did you get your foam. Now im in need of replacing my allae’s interior foam but does not want to pay a lot for what puresoundsales is selling. Although im not in UK, I will rather import if it is cheaper.