Irony, irony. A two way stumpy rectangular box from the 70s with sharp corners driven by solid state amps with LM318s in the audio path is considered 'the sound of the show' by many of the attendees.
So despite all the 'progress' in elementary valve amps, oxygen-free copper, yonic horns, high tech cone materials and ultra-rigid organic speaker enclosures it comes to this...It simply confirms what I knew all along: hi fi peaked in the 70s and 80s, and is going backwards. Contrary to what someone said earlier, speaker design is just about slapping some reasonably-compatible drivers in a big rectangular box and setting reasonably-appropriate crossover slopes and frequencies, phase correction and time delays - all as easy as rolling off a log with an active setup, and no need to economise with two way: go three. Compared to today's 'high end' travesties it is guaranteed to sound sweet - as yesterday's attendees have found out.
I do, of course bow to your expertise in these matters, but I can't help but think that you are tinkering at the edges between very good and excellent, a distinction which is completely lost on most people. At shows, we hear such horrors that are then written up as utterly marvellous that I think most people would be amazed simply to hear a monkey coffin speaker slapped together following the recipe I outline above!
Interesting reading in this topic! I have heard many conflicting views of LS5/8s over the years, mostly about 'uncontrolled bass' which is improved by using stands and keeping them away from the walls. There are a couple of electrolytic capacitors which, when failing, cause a rising response at low frequencies. These make the 'flappy bass' worse, as expected, until the hum gets unbearable!
Of the BBC speakers designed around that time prefer the LS3/7s actually, though not as loud, and the wide front with handles on the side make them a bit domestic environment unfriendly. I may be a little biased in this matter 'though!
LS5/8s without amplifiers are not too expensive, and would save the effort of finding suitable bass units and all that woodwork.
Of the BBC speakers designed around that time prefer the LS3/7s actually, though not as loud, and the wide front with handles on the side make them a bit domestic environment unfriendly. I may be a little biased in this matter 'though!
LS5/8s without amplifiers are not too expensive, and would save the effort of finding suitable bass units and all that woodwork.
You can certainly make as nice a sounding speaker as you would want based on parts from the 70's. It can also look totaly mundane in design.
In the end the sound quality is tied to refinement in fine tuning the crossover to perfect the balance. This is down to the skill of the designer ( this hasn't, and won't likely, change in our lifetimes) The BBC was very skilled in refining their designs and had the benefits of live musicians next door to compare to and smart researchers such as Harwood to work out some of the details. They were also designing products with a focus of purpose and with no need to follow fashion or please the market.
David
12" bass plus tweeter is actually a rather good design. It's also quite hard in some respects because of the low crossover required, which makes demands on the tweeter and it has a lowish impedance on 8 ohm drive units. The 1969 LEAK Sandwich was a design of this ilk. It's frequency response is simulated below. Dispersion and phase is actually rather good, which is a surprise.
The Wharfedale Melton 2 was similar, and had a good sound too. Definitely not garbage!
The Wharfedale Melton 2 was similar, and had a good sound too. Definitely not garbage!
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To my ears the LS 5/8 completely blew away the very expensive Naim/Neat MF7 system at Scalford.
The rather expensive diy Scanspeak 2-way speakers weren't much good either and proved how getting the crossover right is so incredibly important. With the right crossover those drivers should have produced a much better sound than I heard.
The 12" (Goodmans?) full range drivers with open backs were excellent too. I always thought large full range drivers were supposed to be rubbish because of beaming and breakup but was proved wrong here.
It's surprising what you can learn from going to Scalford and I'd highly recommend it.
The rather expensive diy Scanspeak 2-way speakers weren't much good either and proved how getting the crossover right is so incredibly important. With the right crossover those drivers should have produced a much better sound than I heard.
The 12" (Goodmans?) full range drivers with open backs were excellent too. I always thought large full range drivers were supposed to be rubbish because of beaming and breakup but was proved wrong here.
It's surprising what you can learn from going to Scalford and I'd highly recommend it.
It's a classic school of speaker building!
12" plus tweeter does tend to blow the tweeter though. The 12" is very loud, and not many HF units or 3" fullrangers can keep up with it. Wharfedale tweeters were notorious for frying.
A better approach is to wire two mids in series for 16 ohms, and add a tweeter to help the top end dispersion above 5kHz.
Which is near to what the very lively late 1970's Wharfedale E70 did. A speaker that many people admire.
Is that a two way improved, or a three way? It IS second order electrical filters.
12" plus tweeter does tend to blow the tweeter though. The 12" is very loud, and not many HF units or 3" fullrangers can keep up with it. Wharfedale tweeters were notorious for frying.
A better approach is to wire two mids in series for 16 ohms, and add a tweeter to help the top end dispersion above 5kHz.
Which is near to what the very lively late 1970's Wharfedale E70 did. A speaker that many people admire.
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Is that a two way improved, or a three way? It IS second order electrical filters.
Or Cerwin Vega!
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The Wharfedale Super 8/
Thing is, if you sim it, it works out better than any other three way I can think of! Power handling is excellent. Even phase and impedance is exceptional. All on a simple crossover. My flatmate had some, and I gotta be honest, they blew the socks off my 3-way BBC monitors.
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Or Cerwin Vega!
Thing is, if you sim it, it works out better than any other three way I can think of! Power handling is excellent. Even phase and impedance is exceptional. All on a simple crossover. My flatmate had some, and I gotta be honest, they blew the socks off my 3-way BBC monitors.
Who would have known? I guess you can't judge a book by its cover....
But that wouldn't be DIY!
As it goes, Graham are doing a good job on an LS5/9 with a smaller Volt 8" polycone and the Audax TW034 tweeter. A lot of equalising needed though.
But I see no reason why you can't use an 8" or 10" or 12" paper bass. It might be a lot simpler filter really. Most of them are quite well behaved.
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Troels is well acquainted with the advantages and shortfalls of modern speaker design. His endorsement of Briggs' Open Baffle cannot be discounted as mere nostalgia. I say have some fun and build a pair of OB using new or old drivers, WAF be damned!
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