Avondale crossovers for Naim SBL

[YNWOAN]

My friend Ernie recently pointed this eBay add out to me and I think it's worth creating a thread for it as I know there are a lot of SBL users on the forum:

http://rover.ebay.com/rover/1/710-5...0001&campid=5338728743&icep_item=291639554786

I remember that some time ago Les posted about his intention to produce an upgraded SBL crossover but I thought it had never happened - apparently it did. Oddly, it's not Les who seems to be selling them though. If you look at the pictures it's really a rather nicely constructed thing and allows for bi-amping or bi-wiring if desired.

 

[Martin D]

Great news, thanks

 

[YNWOAN]

There have been a few threads about upgrading said crossovers so I thought it may be of interest - not as interesting as mains cables obviously .

 

[337alant]

Looks nicely made and Ansar super sounds are excellent polyprop caps

Alan

 

[mercalia]

seems rather expensive?

 

[orangeart]

seems rather expensive?

It does doesn't it! If anyone wants SBL crossovers making of excellent quality, in a nice external box I'm sure it can be done much cheaper. In fact I may work it out. This looks to be the standard circuit rather than an upgraded one. GB maybe?

Stefan

 

[YNWOAN]

It's not that cheap I agree. But there is a lot of prep work involved.

I don't know the value of the resistors or coils (because they can't be read from the pictures) but the rest of it is the standard crossover (as it probably should be).

 

[orangeart]

It's not that cheap I agree. But there is a lot of prep work involved.

Agreed.

 

[rontoolsie]

Sure it's not cheap. But this is less than the cost of just the bundy cable if you went active. ..never mind the additional expense of a snaxo....a supercap. ..one more power amp...two extra levels of rack space...one snaic5..and one extra run of speaker cables. Then ask yourself if this upgrade is value for money or not

 

[RustyB]

I don't know the value of the resistors or coils (because they can't be read from the pictures) but the rest of it is the standard crossover (as it probably should be).[/QUOTE]

Or should it?

I have pondered about the possibility that the, er...unusual... voicing of the SBL which is a turn-off for some (me included) is a result of the passive XO being compromised for the sake of compatibility with the active version.

Normally a vital part of speaker design is tuning the crossover to, in the first instance, produce a respectably flat FR, and then fine tuning by ear.

It would be interesting to hear SBL's driven by a crossover designed along those lines.

 

[rontoolsie]

Going active with any Naim speaker does not change the voicing...the transfer functions of the active and passive x/o are pretty much the same, and are generic third order without attempts to compensate for non-linearities.

But dramatically improving the components of the passive x/o can dramatically improve the sound and by virtue of being 'lossier' have fuller harmonic balance. I've done the PAXO vs Supercap/Snaxo vs custom built passive crossovers and ended up with the last option.

Do not think that the Snaxo is not without coloration-it is nowhere near transparent-but it is much MUCH better than the vestigial passive crossovers that were designed to offer much lower performance than the Snaxo, rather than the Snaxo designed to outperform even the Paxo. A custom passive crossover however can outdo the Snaxo as its response can be tailored with relatively little extra componentry....customizing a Snaxo would require much more in the way of components and render it exclusive to a single speaker (and much more expensive too). So there would have to be one model specific for the SL2, the SBL, the IBL, the Credo, the Intro, the Sara, the Kan1, the Kan2, the Sara, the Tukan, the Kaber etc etc.

 

[muzzer]

seems rather expensive?

Have you seen the price of the other stuff he sells

 

[YNWOAN]

Just had a look - cripes he's a bit optimistic isn't he? Over 8K for a pair of reconditioned Briks, no crossovers or stands! £800 for Kans - is it some sort of spoof?

If anyone is interested in these crossovers they would be best to deal with Les directly I think.

 

[Eyebroughty]

He has been doing this for a year or two now on eBay, if you check his most popular items from the link at the bottom of one of his sales it appears that his third most popular item is a £32,000 active Linn/Naim system!

 

[James]

Normally a vital part of speaker design is tuning the crossover to, in the first instance, produce a respectably flat FR, and then fine tuning by ear.

It would be interesting to hear SBL's driven by a crossover designed along those lines.

I offered to do this a while ago when I was in the midst of my own loudspeaker designing adventures. Sadly, I had no takers. Somehow, I suspect that would have been an exercise in futility as I think a 3/4" tweeter is a fundamental mis-match with an 8" mid-woofer.

 

[torstoi]

I offered to do this a while ago when I was in the midst of my own loudspeaker designing adventures. Sadly, I had no takers. Somehow, I suspect that would have been an exercise in futility as I think a 3/4" tweeter is a fundamental mis-match with an 8" mid-woofer.

That's interesting James, as I don't have a loudspeaker designer's perspective.

Can I understand this that you think a higher quality crossover would rather highlight the fact the tweeter and mid-woofer are not matching well,
which is less apparent in standard form ?

 

[Maxbertola]

So it seems I am one of the very few who has a pair of SBLs mkII with standard crossovers, drives them with a Supernait and has a very balanced, natural sound with life-like timbres and sufficient realism?
My whole SBLs plus new grilles cost less than 3/4 of these crossover upgrades, so I wonder if there's anything wrong with my system.

 

[scottcarpenter]

Just had a look - cripes he's a bit optimistic isn't he? Over 8K for a pair of reconditioned Briks, no crossovers or stands! £800 for Kans - is it some sort of spoof?

If anyone is interested in these crossovers they would be best to deal with Les directly I think.

I agree. Although, I considered a pair of Briks a few years backs and contacted Simon to see what he had on offer. I didn't buy a pair but he was extremely amiable, very generous with his time and incredibly knowledgeable.

He's evidently a real enthusiast but at those prices I would probably consider other options!

 

[orangeart]

This is the nub of the slightly odd voicing of these speakers or any speakers trying to cross from an 8 inch driver to a 3/4 inch driver or a 1 inch driver for that matter.

Consider that a tweeter can only go so low, I believe that naim cross at about 2.4khz at which point this tweeter is already starting to drop off and has ran out of steam completely by 1khz. Ideally this tweeter would be used in a system where crossing at 3.5-4khz is possible, probably a 3 way with a 3 inch mid driver. The problems caused by crossing a tweeter this low are firstly power handling, this tweeter is rated at 90w at 4khz at 1.2mm excursion. Linear excursion is stated at .8mm which probably makes the usable (without considerable distortion) limit about half that power and that is at 4khz where the tweeter is happy, we need more excursion for the same level as we move down in frequency.

Moving onto the midbass driver, we have no choice but to crossover higher than a driver of this size can realistically do. The classic set-up is a 6inch crossing to a 1inch at about 1.8-2.3khz and even that is a compromise. A driver starts to beam (become more directional) as the wavelength it produces becomes shorter than the diameter of the come. Obviously this happens much lower with a larger driver. 1.7 khz with a driver this size. I've not seen the data sheet for this particular driver but it's usual for a cone to start breaking up not far after this and distortion sets in. We are asking both drivers to cover much more of the spectrum than is ideal, the midbass driver is going to have to cover almost another octave before we even start filtering it. A driver mating to that scanspeak tweeter will need to rise in response as well to filling the natural fall off of this tweeter which means that right in the middle of the crossover frequency where the 'presence band' is we're going to have to listen to a beaming driver that is being driven to distortion.

At least the 3rd order bessel rolls of quickly and gives decent group delay if done well.

Stefan

 

[S-Man]

Somehow, I suspect that would have been an exercise in futility as I think a 3/4" tweeter is a fundamental mis-match with an 8" mid-woofer.

That was my experience with Proac R2.5 clones. The original very artfully papered over the crack by a bit of extra presence region on-axis. When you've got used to something with an even power response this compromise is no longer satisfactory.