Why do you need a speaker crossover - discuss

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Originally Posted by BTH K10A

I've given this thread some thought over the weekend.

I ask a simple question to clarify and ambiguous statement, get a reply that reinforces my "wrong" assumption and then find myself subjected to accusations and insults.

I had decided to carry on and avoid or drop out of any threads where he posted but, the implications of, and the sheer hypocracy of his last sentence have done it for me. This is crap that I don't need.

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I don't want to be the cause of yet another member throwing a tantrum and leaving, as Marco says none of this post was about you. You just happened to be the final straw. But ask yourself, what is the title of this thread, why couldn't you post on subject, why do you have to make the subject the poster, me. It always has the potential to lead to conflict, especially if that was the purpose of the intervention *which I am not saying is correct in this case*. It really was frustration with all that had gone before, but really when it had been said so many times that it was referring to early BBC speakers it should have been obvious, So you suddenly bringing in JBL just made me pop!

For me it just looked as though you were deliberately questioning to find an angle and excuse or a missed or mistaken word in error in order to pounce with ad hominem, as so many others had done before. *I* was not the subject of the thread, so why talk about me, why try to draw me into conflict. For me there can only be only one reason, to try to make me lose my rag and get me removed. It is not as though it is something new, I have been stalked across the forums by certain individuals for at least a couple of years with the one aim to get me off all the forums.

Now you refer to my paranoia, well I do have one because I am coming to the conclusion that my opinions tread on too many industry toes, and at least some of these stalker are industry shills.

So don't be silly unpack your bags, go into lurk for a while, and as I have been told "chill".

Back to lurk.

Well this thread created a lot of curfuffle and the BBC thing was brought up again even though I didn't initiate it. So anyway some new information that I think is important to copy here.

I have a customer with NVA pre and power amps using Spendor S6es speakers and he has been singing the praises of the combination on subjectivist, so I decided to investigate them and I find *a more un BBC like design it would be hard to find*

I quote my post on Subjectivist:-

"Well I have just investigated those Spendors Blue Nile uses. Simple well made ported 2 way floor stander with minimum load impedance of 6.2ohms and reasonably simple crossover. THIS IS NOT A BBC TYPE DESIGN!!! they obviously are capable of making good loudspeakers and these are so far removed from their early designs to make it like they were made by a different company."

So as I said before that I thought the old BBC type companies now only paid lip service to the design principles for marketing purposes turns out to be true for this speaker from this company at least.

Spendor today aren't the Spendor of the 70's, for good and bad IMO :)

I re-wired my BC2's the other week. HiFi Dave had been on at me for a couple of years to do it and Alex having a go at his 401 really got me going (summat better had :lol:) You know, I don't think the crossover in the BC1 and 2 is hugely complicated by some that I've seen and, without looking again at the scematics over on the Yahoo Spendor group, I don't think there's that much in the signal path. For me, what makes it look complex is the bit for the little Coles super-tweeter, which looks a bit ridiculous for a 10-12kHz region crossover. Not being a speaker designer, just an enthusiastic amateur, I dare not comment further. The one Spendor which has a frightening crossover (to me at any rate) is the BC3. I'll try to find some pics when I get home and post them...

By the way Richard, I was once told that the radio transformer type of inductors were "better" than those conventionally used, although I'm sure you can tear this statement to pieces, certainly for power handling, which none of the domesticated BBC have..

TTFN

It is the principle that is the problem Dave. Normal principle (used by all UK manufacturers pre BBC design and all US loudspeaker), do it physically if you can and only do it electrically as last resort. BBC design principles, do it electrically and only do physically what you can't do electrically. Their other principle is voicing to the spoken voice, normal companies voice to music.

Re inductors, I hate them (as with all coils) and will only use them as last resort, and then large and air cored - no ferrite!

I really do see where you're coming vfrom, but I ought to suggest (please) that the human voice is precisely what our ears are most used to hearing???????

I should also like to correct, or at least modify the view that the BBC tried to solve all the problems in the crossover. I'm not sure that's entirely true and although I haven't studied their research papers in depth, I'd respectfully suggest that the engineers of Harwood's time and before, really DID know exactly what they were doing, cared passionately about the end result but were hampered by the technology available at the time.

I've heard from a few engineers now that paper cones could be a nightmare way back then. maybe AR got utter consistency, but the pulp "mix" could apparently vary if you weren't absolutely careful. The same with the gloop Tannoy use(d) to dope the corrugated surrounds of their DC cones. OK, I know you'll argue that the transition to bextrene was fraught with other dangers, and I think any of the "BBC Legacy" designers will agree with you. Polypropylene ain't any better either apparently, as the "BBC Crossover "smile"" was put there to hide things going on in the drivers - and my gawd, I live with an exaggerated version of this every day :lol:

What all the rubbish above is trying to say, I hope, is that these days, the BBC derivative manufacturers (the two main ones and ONE in particular) have designed FAR better drive units which do the job with the absolute minimum of messing around. I'm glad you didn't dislike the Spendor S6? and if you think they were tolerable, you'd hopefully be very impressed with harbeth's current models. OK, the tonal balance may not be to your taste, but the way they engage the listener and the detail at domestically-necessary low volume levels is remarkable I think myself. Other well rated "hifi" speakers, like Zu Druids for example, needed the a*se thrashing off them to even begin to give any bass weight or power and at low volumes sounded very unrealistic when I heard them. In comparison, the Tannoy Turnberry was a revelation - a tragedy that they cost so much and noone in the UK will pay the price asked - even half price is difficult to achieve for mint used ones, sadly. people don't know what they're missing, but I digress.

Apologies, I was trying to defend the BBC engineer's way of doing things in the 60's at any rate. It would appear that later BBC models were designed more by commitee once "the gentleman" Dudley Harwood retired, ending an era, and started Harbeth going in 1977. The LS5/8, 5/9 and especially the truly dire LS5/12A, were anything but neutral apparently, although the 5/9's I have coming (when I can get to collect them) may suit my room better in the bass.....

Well I will just have to disagree with you. I was around at the time and was intimate with what was going on. To voice to the human voice is OK but they had a fixed idea of the human voice and that is the BBC announcer using the BBC approved accent, I don't think you realise how fixed and finicky the beeb were in those days, they even taught there announcers how to speak.

Everything I said in my post is correct and as all of them were about 20 years older than me at the time then they are all highly likely to be dead. So take it or leave it - I lived it!

I haven't heard the Spendors *I investigated them as to how they were designed* and what the constituents are. So they could still sound crap IMO I just don't know, but we are onto a good start as one of my customers loves them.

Regarding modern versions and your reference to bass performance, well if you seriously think a port can ever give you real bass then you are sadly deluded. It will make you think you have bass, but it doesn't time, and is often a one note fart. There are only two ways to get correctly timing bass they are infinite baffle, or open baffle, preferably line array. Every form or port or line makes the bass not time.

I agree about ports, but you know as well as I do (better!) that it's to do with port tuning. The ATC 100A's I had were well ported, but nowt ever came out of it as it wasn't tuned to increase bass per se. Having said that, most smaller modern speakers these days depend on the one note fart to give any bass at all IMO. As for my own speakers, the port hole has been better tuned along modern thinking recommended lines and I can live with the results. It certainly doesn't honk like old BC1's did, but all I'd graciously ask is that you don't tar all BBC derivatives with the BC1 or Rogers Export brush, as things have moved along quite noticeably. Not sure about Spendor's current "Classic" series as they refused to allow us to try them once the take-over was completed and the "S" series came along. I believe they've tinkered with wiring and cap changes, but the rest is similar to their late 80's output I believe, along with the rapidly ageing and hardening rubber cone surrounds which lose all the bass after several years. I believe this has been looked at in current models, but some of the stuff from the 90's seems to suffer I'm told, including some ex-video editing suite SP2/3's a mate now owns.

It is *very* simple, things have moved along because those companies (including Harbeth) do *not* design to BBC principles, they pay it lip service for marketing reasons.

I really don't care how well you tune a port it still does not time to the music, and if it is there then music *has* to come out of it. The best thing you can ever do with a port is put a sock, or preferably a few socks, in it.

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Originally Posted by Dr Bunsen Honeydew

Bi amping is a different matter.

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Hi Richard, or anyone else, would bi-amping, or tri-amping for that matter, with gain/power matched amps into sensitivity matched driver units invalidate the requirement for a crossover?

Or am I being too simplistic :scratch:

By splitting the legs of the crossover then you simplify the load conditions on the amplifiers being used, but you still need the crossover. Or you need to move the crossover to be at line level as in active crossovers so involving power supplies unity gain amps hung around filters etc etc, even more gumf.

The answer to all this is to go back to basics, complication never solves anything. Select drivers and cabinets (in shape size and material) and if need be alter the physical characteristics of the drivers so they don't need all this electronic gumf hung around them.

Or do as Paul Hynes has done, as that seems the best application of full range drivers as I have seen - then no crossover, no doping, in reality not even a cabinet. But it is a solution for real hi-fi nerds and tweakers.

One rule, simplicity with excellence (both design and material), problem solved.