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Aftermarket crossover for Naim speakers (DBLs)

We have spent the last year listening to many and various components this is our list of the stars we have found.

Capacitors

Size varies dramatically, rule of thumb is the bigger is better.

vDC is another guide to performance as, so some thinking goes, the higher this value is, the less the loss.

Naim tends to use Philips, Alcaps, ICWs and Solen Fast Caps. Of some merit are the ICWs used in speakers like the Quad 11l, and the Solen Fast Cap. The Alcap is very mediocre, as is the Philips.

Stats for the Alcaps and Philips are

Alcaps, 50/100vDC - £1.09, Philips 100vDC - £0.50p both have tolerance of +/- 10%

Our Favorites (all prices are for 4.7 micro farads)

Low – mid priced.
Solen Fast Cap 400vDC - £1.84
Good sounding reasonably priced Cap. Easy to source.

AmpOhm 630vDC, tolerance +/- 10% - £5.25
Very good sounding cap. Rare, limited values and large

Audyn MKP QS 400vDC - £2.08
Good value.

Higher Price
Audyn Cap Plus 800vDC, tolerance +/- 2% - £15.85
Outstanding performer, highly musical. Expensive and large.

Mundorf Supreme 800vDC, tolerance +/- 2% - £17.00
On Par with the Audyn Cap Plus, may be more smooth but less dynamic.

A much more extensive piece of research, including Hovland, North Creek & ERO can be found at

http://home.zonnet.nl/geenius/Cap.html


Resistors

Lots of theories here, inductance cancelling is favoured by most. Power handling needs to be about 10watts in most cases. We tend to steer well clear of the ceramic ‘white brick’ style ones.

Low-mid
Mills, 10-12w, tolerance +/- 1% - £3.00
Well respected audio resistor and rightfully so.

Intertechnik MOX, 10w, tolerance +/- 5% - £1.20
Good performance price ratio

High Price
Caddock MV311, 10w, tolerance +/- 1% - £25+
Outstanding performer, expensive and difficult to source in low numbers

Audio Consulting silver wound, no stated tolerance - £40+
Has no sonic signature at all, the perfect resistor but very large and super expensive.

Inductors

We are only interested in Air Cores. We feel that, despite their size, they very comfortably outperform any Ferrite cored inductors. Foil also sounds better due to it’s skin properties.

Jantzen Cross Coils. 12 AWG Foil (DCR 0.330 Ohms @ 2.7mH) £20
Excellent product and widely available.

Alphacore 12 AWG Foil (DCR 0.235 Ohms @ 2.7mH) £19
Excellent product.

Jensen 12 AWG Foil (DCR 0.300 Ohms @ 2.7mH) £23
Unique wax insulation gives a very natural sound, short of silver wound inductors, the best inductor by a margin. Very difficult to handle (due to wax) and mount.


All the prices tend to reflect UK market and will vary subject to volume. The bottom line with any of these components is that they will make a big difference to the performance of the crossover.

Adam
www.audio42.com
 
Thanks for the above link regarding subjective capacitor testsing.

Later today (if they come in) I will be able to give the new Cardas caps a listen- although they will probably take a few days to sound even close to right.

And their price?....... $800......EACH!!!!

Also...today is day three of constant run-in for the x/o containing the North Creek power resistor. Whether its the resistor 'burning in' or the entire crossover having to reset after being unplugged and moved around, things have changed considerably for the better. Compared to the sound I was getting 3 days ago with the Dayton resistors, there is a bit more life and inflection in the midrange and the awful honky colorations I had experienced on the first day are now banished. These will now become my standard power resistors-and not too expensive at $3-4 each.

Later today I will also be getting back the crossover containing a switchable set of midrange capacitors-Solens vs the Hovlands. But since it will take at LEAST a week to run it, I will probably not be able to say too much about it today, except to confirm the very unripe nature that I fully expect now in all passive components.

Dare I risk spending $6000-ish on Cardas capacitors to populate my crossovers? Not too sure about that- but it still would be cheaper than going active (again).
 
Adam - given you're a commercial venture principally manufacturing crossovers, it's good of you to share your findings; thanks.

I agree with the comments on Audyn caps - I have used them in several different speakers to very good effect, even when replacing allegedly 'good quality' film caps. Very good value indeed.
 
Ron et al,

Whilst it is a worthy goal to improve one's passive crossover network to the maximum possible, it is a good idea to keep in mind what they are feeding. The Scan-speak D2010 (USD57.00 each at Madisound) tweeter on the DBL is an adequate tweeter, but certainly not state of the art. For that, you will need to look at the Scan-speak ring radiators, Seas Millennium or (the darling of the DIY world) Hiquphon OW series. Likewise, the DBL mid - which I believe is a Mordaunt-Short sourced driver originally used in the IBL, and later adapted for midrange duties. Not sure whether this involved shaving weight of the moving parts, but it has been around for a while and certainly not state of the art. The cutting edge midrange drivers today come from Seas (Excel range), Scan-speak (12M, 15M) and Skaaning/AudioTechnologies just to name three.

Getting the best possible passive filters fed by premium electronics into comparatively low cost drivers is akin to cladding your latest Ferrari with Kumho tyres - sure you know you have a good feel for what the car is good at, but nowhere near exploiting the full potential of its engine and chassis.

When you sought to redesign the DBL PXO from the ground up, I had no idea you were prepared to spend the equivalent of active money to get it right. If I had known, I would have suggested that you redesigned the DBL from the ground up, maybe keeping the ATC 15-inch bass driver, but certainly replacing the mid and the tweeter - and designing a new PXO with premium parts for premium drivers.

At least you now realise the potential, and perhaps there is a chance that you can recycle some of the passive components you have invested in so far if you choose to go down that route.

James
 
James,
Thanks for the insight. I have actually already ordered a custom built pair of midrange units through my speaker building artisan @ $150 each that looks like it will fit the bill. The tweets are also scheduled to be replaced as well. Of course this will require some redesign of the crossover, but not such a big deal. The ATC bass drivers as stock have very high 2nd and 3rd harmonic distortion at anything over 20Watts and only allow an excursion of 2mm. I know that Naim allegedly rebuild these drivers so who knows what the final product is capable of. I also have a 15" driver in mind that I may well stick in the DBLs, each coming in at an OEM cost of $900. Oh, and the OEM cost of the DBL tweeters is $29 each...the advantages of going through an estabished speaker company is OEM price availability. I saw the model of the DBL tweeters today through the only driver modelling progamme extant, and anything above 12k results in severe breakup of the fabric dome. I am looking towards a beryllium driver to replace this.

My initial goal was to see how far I could push the DBL and still keep it a DBL. As it turns out, even without touching anything but the crossover I was able to get a performance better than any active configuration I had tried. I am now sufficiently motivated to address what the next weakest link is- the drivers. I am fully aware that at the end of this I will no longer have a DBL speaker, only a DBL carcass with highly specified drivers and passive components. If this were a commercial venture these S-DBLs would probably retail for $40k, but cost me maybe an additional Supercaps worth of expenditure to implement.
 
Ron,

Unless you are particularly endeared to the DBL look, have you considered custom-building a new loudspeaker from the ground up? It's a bit of a lottery expecting a new bass driver with different T/S parameters will work in a DBL cabinet, especially one that has a PAR/aperiodic vent within.

It's a shame we live an ocean apart.

James
 
James.. you mind reader you. Yes, I have also consigned a pair of custom speakers built..we are still looking at driver and design options. I am currently favoring an acoustic suspension design. Provisionaly it looks like I can have a 6cubic ft enclosure, three-way design that is +/- 0.5 dB from 30Hz-20k and maybe 2 dB down at 20Hz, no more than +/- 10 degrees of phase shift etc etc.
Downside is they may end up weighing 350 pounds plus each.

Daryl has also found a way to use a single driver design (no crossover!) in a linear array, whereby a tall slender speaker containing 8 drivers can have 98dB efficiency and flat to 25Hz with near perfect phase. He refuses to tell me how he has done this until the patent application is processed. But I have heard a 2 driver prototype (both identical drivers of course) that shows exceptional promise. I would love a pair of these too...but currently I only have room for a single pair of speakers in my main audio room.
 
Have the latest xover from Darryl. Put it up last Friday. It will not be stupid good until next Wednesday. As Ron states, it has a mid band "Ick" as part of the run in. I do know what it will sound like in a few days though. Damn great!..
I will also put in the new drivers and the Cardas wire in and on the DBLs.

James:
Hows it going chief? Please tell me it is up? N.Z. is only a 22 hour flight. Come on over for dinner and we will do it in grand style!

San Fran cancelled and I might be moving to Las Vegas. See you at C.E.S.

You make some real pretty speakers dude!

Time for another Ausie beer......

Regards,
Marc
 
Marc,

"Hows it going chief? Please tell me it is up?"

I can assure you I'm more frustrated than you waiting for the blasted installer to make time to see me. They all seem keen to engage, but when I tell them I already have the aerial, and one that has 17 elements, they freak.

"N.Z. is only a 22 hour flight. Come on over for dinner and we will do it in grand style!"

I'd love to, and whilst our dollar is comparatively strong - buying a R-T-W ticket to visit USA, UK and Asia is not entirely out of the question. Finding time off from work, unfortunately, is ...

"You make some real pretty speakers dude!"

Why thank you. I expect the latest E-V to be a real cracker in terms of looks and music making abilities.

"Time for another Ausie beer......"

Indeed it is, especially as summer approaches for us.

James
 
Ron,

"Provisionaly it looks like I can have a 6cubic ft enclosure, three-way design that is +/- 0.5 dB from 30Hz-20k and maybe 2 dB down at 20Hz, no more than +/- 10 degrees of phase shift etc etc."

You wanna be real careful with that kind of response. Don't forget to take room gain into consideration, where anaechoic response down to 30Hz (-12dB @ 15Hz) might be all you need to go flat to 20Hz in your room.

"Daryl has also found a way to use a single driver design (no crossover!) in a linear array, whereby a tall slender speaker containing 8 drivers can have 98dB efficiency and flat to 25Hz with near perfect phase."

Drivers are essentially minimum phase devices, and so a crossoverless design will give you as good a phase response as you're gonna get in the real world. However, I'm not aware of any driver that can cover the full audio spectrum without some form of equalisation. I wonder if it's the same Daryl who advocates series resistance to massage low-Q drivers into sealed boxes on the Madisound forum. If it is, then it's a small world indeed.

James
 
Single driver speakers- a fascinating concept with some of the advantages of a full range electrostatic driver hybridized with the advantages of a dynamic speaker.
As James points out, no drivers are linear (or of equal efficiency) throughout the frequency spectrum. The prototypes I heard had a rough form of equalization applied- actually it was a passive resonator circuit that lies in PARALLEL to the signal that allows true linearity. I have also heard the same speaker equalized with an active parametric equalizer (which of course is in series) that was nowhere as good-active equalization takes a big bite out of phase coherence.

I got the latest crossovers yesterday. The 30 mfD capacitor in the midrange is now switchable between the standard Solen cap and three much more expensive paralleled 10 mfd Hovland caps. Each needs to burn in...right now I have had the Hovlands in circuit and playing for just over 12 hours, and I am very impressed by what I am hearing this morning. Of course for the last week until yesterday I was using the prototype pair without the Cardas wiring-which has a suprisingly disproportionately large contribution to the final sound.

Here is a picture of the Solen cap lying on a bed of Hovland equivalents...check out the toggle switch allowing for comparisons on the fly. The green power resistor is the North Creek/Ohmite one- which I concluded is a modest improvement over the Dayton.

Hovlands vs Solen.
 
I wonder if it wouldn't be fairer for comparison's sake to use three 10uF Solens in parallel, too.

Best regards,

Oliver
 
"I wonder if it wouldn't be fairer for comparison's sake to use three 10uF Solens in parallel, too."

That's a good point, but the Hovland's will no doubt still be better by a clear margin. The Solen's are pretty much universally accepted as being excellent for the money though - certainly light years ahead of what is the norm in even 'high end' commercial speakers.

Mr Tibbs
 
When I was developing the XO for the E-IIIs, I hardwired everything point-to-point just as Ron has done. When I tweaked the XO, I would simply swap a component in or out, adjust the layout of the board accordingly, and simply remelted the solder left on component legs to rejoin them. Over time, as I thought I was making progress, the audible results were less convincing.

I tried to retro-fit a better midrange (Seas M15CH001), which required the wholesale replacement of the Band-Pass section. One the whole, the M15CH001 certainly offered a lot of promise, sounding a lot clearer and more organic, and yet with my numerous tweaks, it sounded wrong and no matter what I did, I could not get it to sound right. When I put the old Band-Pass filter section back in and the original Seas CA15RLY, I thought I would at least restore what was working well before.

I was wrong. It sounded even worse. The clarity I had now sounded muddled and the wrongness remained. Something was surely amiss, and in desperation, I thought the least I could do was remake each and every solder joint again. So I did.

What a fantastic revelation it was. The E-IIIs now sounded exactly as I had intended them to sound, and better than I remember them ever sounding. All due to relaying the XO with solder terminals and clean joints. I was gob-smacked that such a trivial matter could result in such a change. Perhaps it wasn't so trivial after all.

This led me to think that I had not heard the M15CH001 at its best, but now that I'm knee deep in saw-dust dealing with the E-V and PFM-Special, I'll save the M15CH001 for another design. The E-IIIs are at their definitive best today, and will remain unchanged. Even Steve commented yesterday that they sounded warmer and much less mechanical than he remembered them.

My point after all this rambling? If something seems amiss after swapping parts in and out, take a closer look at the solder joints, and where possible, remake them with fresh clean solder. Old solder simply remelted to reform a joint does sound audibly worse IME.

James
 
"My point after all this rambling? If something seems amiss after swapping parts in and out, take a closer look at the solder joints, and where possible, remake them with fresh clean solder. Old solder simply remelted to reform a joint does sound audibly worse IME."

Very much in agreement with James here. It does make a difference to have everything soldered up carefully and with special attention paid to wiring layout. There is a lot of current flowing in a XO, so as much star-wiring as possible reaps dividends.

Mr Tibbs
 
Originally posted by James
.....Even Steve commented yesterday that they sounded warmer and much less mechanical than he remembered them.
.....James
Click to expand...
Confirmed when I got home afterwards and listened to the Dynaudio's - the vocal realism gap had definitely closed a bit. That might have been the first time I've heard the E-IIIs at their best as I suspect you had already made many changes to the XO before I first heard them.

Steve
 
I would humbly suggest to Ron that he might well be better off jumping ship, selling the DBLs and getting a pair of ATC 150As instead. It will be cheaper, less hassle and almost certainly far better.
 
Blzebub,
I would So disagree with your opinion. You have never heard the DBLs if you have not heard them in this mutation. The sound is So far ahead of what you have heard any Naim speaker do active or otherwise...I have heard ACTs and I would humbly suggest you come on over to Rons or my house for a listen. Any hastle is well worth the money,wait,or r and d frustrations. As Ron and I move forward, we look forward to improving these wonderful speakers another 50 to 100 percent.
In addition, I look forward to Naims ability to put forth a slew of new and wonderful products to allow me to hear even more music.....
 
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