New cable for Naim 500 to Isobariks

[MikeMusic]

Prompted by the discussions about Tellurium....

My Naim cable connecting 500 to Isos is, and possibly needs to be odd
Single banana out of the amp soldered into 3 separate stero cables connecting to the 6 inputs in the crossovers in the base of the Isos
- which then have 3 more pairs of grey (Linn cable I assume) going from the crossovers into the back of the Isos
Can't be that clever

Is there a better way not using 3 sets of cables and making it more efficient ?

[MartinT]

What terminals does the 500 have, Mike? You may be limited to using a 'hydra' type cable purely because of the single set of terminals available to you.

[MikeMusic]

Bananas from the 500 - and all round on the Isos. This was the penultimate Iso design I think, after XLRs went

[MartinT]

In that case you're stuck with a hydra (one to many) type cable design. That's not to say that you have to stick with your current cables. If they're Naim then they can be easily improved upon.

Have a friendly dealer make you up a set from your favourite cores?

[MikeMusic]

Aargh. Not the news I wanted.
Could a single stereo cable go to a beefy, solid distribution/chocolate strip affair and then into the 3 pairs in the crossovers ?
The 2nd lot of cables from the crossovers to the back of the Isos looks poor quailty.
Would I get a disproportionate improvement by just upgrading those ?

[MartinT]

Well, yes you could feed a single beefy cable to the crossover and short, better quality cables to the individual drivers. You may have to DIY it but short of some photos to look at it's difficult to comment further :)

[DSJR]

On a tangent, I wonder if the NAP500 is really suitable to drive the 'Briks, since the amp uses bridged? standard circuits. if wired inside for double-mono, then it'll be better than ever, but if wired for double the voltage, as my crowns are, then they may have difficulaty with the 3 - 4 ohm load of the 'briks (3 ohms in older ones across most of the frequency range).......... Of course, had the amp really not liked it, you'd have had a blow-up yonks ago, but might be worth checking...

What the fugg is wrong with Naim A5 cable except for it's difficulty in soldering the way you want? The K20 isn't a bottleneck, unlike the passive 'Briks, so I really wouldn't bother...


P.S. if you didn't like me much before after what I've written above, you're going to positively HATE ME now for what I'm going to say...

GO ACTIVE

Sell the NAP500 and try to get a six-pack of 135's and get them properly serviced, together with the active crossover if you can find one. Failing that, ask les at Avondale about having three of his NCC200 based stereo power amps (you won't need the regulated power supplies at all when used in active mode as long as the power supplies are rated to deliver and not sag when driving the four ohm loading - he'll know what to suggest)...

Put it this way, active 'Briks with smaller Naim style amps of 180 and higher will ALWAYS beat the terribly compromised passive ones - internal crossovers, improved model speakers with external crossovers - been there and done it so many times in the 80's and early 90's - and we were one of the top three Linn-Naim dealers through much of this time and sold plenty of PMS 'briks with Naim amps (I also have experience of meridian, Nytech, Linn and Krell driven active 'Briks, but that's only going to muddy the water)...

The VERY best I EVER heard passive 'briks was around 1980, when we had a QMI Gain Cell power amp on loan. I have no idea how it would rank today (it possibly wouldn't for all I know), but this thing was 200WPC into 8 ohms, 400WPC into 4 ohms and would do 800WPC I believe into 2 ohms - that means around 500 - 600WPC available. My god, didn't the demo 'briks come to life, shaved off most of their midrange colouration and they just drove the big dem room with absolute ease, the basic "high fidelity" of reproduction shooting into B&W 801, KEF 105 and big IMF territory and beyond. When this amp went back, the naim 250 sounded grainy and, well, flat in comparison (Naim preamp used all through I seem to remember but it was thirty years ago now)


Sorry sir, not the answer you want, but something worth thinking about if Isobariks are to remain a part of your music listening... Just fannying around with wanky wires is only going to polish the thing you have, not necessarily make it better.....

[chris@panteg]

I thought the NAP500 was the top Naim amp at 15k ? Should be more than adequate for the Briks .

[MikeMusic]

I can understand how unclear this is cos I spent some time looking and thinking and looking and thinking......
It surely is a stupid arrangement, certainly in 2012 woth what we know about cables
Years ago I delegated camera work. This hasn't worked so I need to get over the barrier I have and into using a camera.

[MikeMusic]

Dunno. It certainly sounded better than the 135s previously there as it should with the price difference.
The current cable works ok. Not certain it is A5 as it was supplied by a dealer with Exposure amps and the Isos. It just seems so Heath Robinson and I now need a much shorter cable run so I have big piles of cable behind the kit

The original path I was treading was to go active. This is why I got those Isos. They can be either. I'd have to add 4 more 135s, a Snaxo. Put in a silly bid oon Ebay for the 500 and to my amazement won it. Around £10,000 off list.
I should be open to an active solution. Perhaps I can pick up 2 more 500s for beer money ?
:-)

[DSJR]

In a speaker with a complex crossover, and three ways are amongst the worst to get right in any case, let alone a 4 ohm one like the 'brik, going active solves all manner of issues. I appreciate some say that moving the passive crossover to an active circuit behind each driving amp causes other issues, but that could be due to lack of design expertise since active operation enables more careful crossover slopes on the drivers (the lower one from B139 to B110 is right in the middle of the midrange..) and if properly designed, minimises phase issues too. The driving amps have a far easier time of it as well, since the loading is much simpler. The efficiency of the speaker is increased as well since there aren't big inductor coils in the way, just the speaker coils, which are enough on their own most often.

A NAP 500 may well be Naims flagship amp, but looking inside one just showed more of the same thats in the 135, just doubled up in either dual-mono or bridged form with extra transformers. Forget the price tag, that's just for cachet and offers no indication of its true quality or performance - I don't think it's ever been "properly" examined by a third party in print either, so it's all subjective opinion and emotion, rather than cold, hard facts.. The 'Briks went out of production twenty years ago now and it's unlikely the few NAP500's sold would be called upon to drive a 3 ohm load to high levels, which is what the 'brik loading is typically. I believe early 300 and 500's had stability problems driving such, but this is from comments on PFM made years ago and I didn't keep links (yes I know the infamous Mick Parry uses a 300 into his old 'Briks, but since he hankers after big 15" Tannoys, so I forgive him :))

PLEASE, I'm not trying to have a go here, but in this case I DO think I know what I'm going on about. I owned three different pairs of passive DMS Isobariks myself during the 80's and have friends who went further with the later ones as the OP has (with re-designed crossovers in the stands). I've dne direct passive DMS with 135's to active with six 135's and three 250's and can guarantee that the active option with 250's was far better IN THIS CASE than the 135 passive option. A full Linn active setup on late 'briks with Bingo-Tunebox (:eyebrows:) and Dirak'd LK280's was a fascinatingly different take as well, gaining over the Naim in some ways and falling far short in others.

The old Exposure speaker cable was a flexible dumbell type as I recall and as long as the internal copper hasn't gone off, should still be fit for purpose. You MUST be careful if you persist with this system as-is, as three sets of fancy wanky wires to the crossovers could triple up the capacitance as seen by the amp and, although modern Naims are better than ever in terms of stability, I wouldn't want to risk an expensive repair bill.

No, my original recommendation stands.. Sell the NAP500, and look around on the used market for an active solution if you keep the 'briks...

P.S. You could always go the AOS way and keep the 500 for now, pending a valve solution (have a look at the Tube Distinctions site) ;), sell the 'briks and buy some good vintage tannoys and get them rebuilt and restored. That would sound better than any of the above :)


Oh Gawd, I've done it again. The poor OP won't know what's hit him. Apologies folks :)

[MartinT]

It's all good advice, Dave. You're the man when it comes to Linn/Naim stuff so I'm sure Mike will have a good think over it all.

[DSJR]

I just hope I haven't scared him off........

I should also refer the OP to the active Tannoy thread - I mean, these in stock unmodified passive form are similar to many less accomplished actives IMO. making even these run active seems to lift them to new heights - and they're so darned efficient you don't need many Watts at all :lol:

[MikeMusic]

Not scared. I was previously aiming at a 6 pack, got sidetracked
An lot of kit to fit in. Perhaps I should have gone for that 10 shelf Mana recently on Ebay to put the 6 pack, Snaxo PSU and other kit on !
My current strategy is to tidy up a bit, pick up bargains if around and get my LP12 back working

[DSJR]

You don't need mana, or fraims, or even Naim bits to activate 'briks these days. When and if you're ever ok to look at an active option, ask Les at Avondale, since his products are very reasonably priced, comparatively speaking and a suitable six channel amp could be constructed in one taller case I bet, with plenty of room for a suitably huge power supply configuration. As for active crossovers, Naim only did very basic filter slopes with no eq or phase matching, so it would be easy for someone like Nick (Lurcher) to make something good as he did for a Tannoyista very recently (can't remember the thread and too lazy to look :rolleyes:)

If the existing cables are neatly done, leave alone and have the ends trimmed if they're too long.

We've been there before about the LP12, haven't we?

[MikeMusic]

Thanks.
I'm convinced by Mana on sound and have quite few piece , not heard on a Fraim
I'd never seen a 10 shelf Mana before and I had to talk myself out of going for it !
Mostly I'm fixing and tinkering with the system at the moment.
Thanks for the contacts