BBC inspired loudspeakers - discussion

I guess this might polarise opinion but thought I'd share some recent experiences with a classic BBC design, and get some discussion going around these old troupers.

The particular speaker in question is the Rogers Export Monitor, dating from 1975 and very close in execution to the BBC LS3/6.
It belongs to that group of speakers all based on the LS3/6 - Spendor BC1, Rogers Studio 1, Export and I guess the latest expression would be the Harbeth HL5.

I didn't expect to like them - but think they are fantastic.
Really dislike the LS3/5a and always have. I find they sound soggy and sat-on, devoid of life and dynamics. But the bigger examples of the breed sound completely different.

They don't do dry, grippy bass in the way that many modern speakers do and dynamically they don't thump you in the chest, but the liquid midband is stunning and the top end is open and delicate. Large choral pieces soar with majesty and authority, and absolutely no grating hardness or artificial presence. In this area they leave many modern designs for dead and in many respects they are close to being a Quad ESL in a box.

There are some clues I think in the construction.
Larger speakers such as the 3/6 and variants seem to allow the thin-wall ideas developed by the BBC to work better than is the case with the smaller models such as the 3/5. Makes sense if you think about - the idea of thin-wall is to push panel resonances down away from the midband and damp them. You can't really do that with a very small speaker cabinet unless using very thin panels, so something like the 3/5 will always be inherently 'rigid'.

Also, the crossover is simpler on the larger speakers.
The 3/5 crossover is incredibly complex, partly in order to passively EQ the response and get decent bass from a tiny sealed box. It works but at a price!

So I'm greatly enjoying a speaker I probably wouldn't have given house room a decade ago.

Anyone else have experience with this group of speakers?
If so lets hear your thoughts, good or bad.

 

I had very good experiences with the rather ugly JR149's. - the cylindrical version of the ls3/5a.

I couldn't believe how natural sounding it was, and how room filling - from a single ended valve amp, which shouldn't have been able to drive them, but of course did.

I haven't used the larger BBC speakers, but have been impressed with them when hearing them.

There seems to be a strange discrepancy between those which are considered expensive and not on the used market - I don't quite understand the kudos that certain particular models are getting. I'd like to know more about why that is if anyone knows

 

I'd really like to revisit JR149s at some stage as that is where I started out in audio back in 1978. I recall really liking them in most respects, but I know I didn't get anything like what they were capable of as I didn't understand how to set a system up in those days and my room was far less than ideal.

Up until a couple of years ago I was running a pair of Harbeth Compact 7ES, so a fairly modern take on the BBC thing. I liked them a lot, a superbly balanced speaker that will happily play any music thrown at it. I'd still have them now if it wasn't for a very cheap pair of 15" Tannoys turning up.

I'd love to spend some time with the Harbeth Monitor 30, my guess is it would be my favourite in the whole range - I loved the C7 but never quite got on with the tweeter which to my ears sounded just a little gritty at the bottom end of it's range. The Monitor 30 is pretty much the same thing, but with a very high quality soft dome in place of the C7's metal dome (I've never heard a conventional metal dome tweeter that I've really liked, though I have no such issue with metal compression drivers for some reason).

Tony.

 

I can live with the small versions electrically but don't particularly like the sound, but the LS3/6 and most other BBC type designs are just plain silly. Why design a crossover that so changes the phase load on the amplifier that the amp is trying to drive voltage 180deg out of phase with current. I just cannot believe a competent design enginer would do this deliberately.

Anyway I dislike the whole BBC design principle. If you have a problem then sort it out in the drive units either by selection or doping or in the cabinets, I know there was little choice back them but the KEF Bextrene drivers were so overdamped and nasty that a paper coned driver doped would have been a far better choice. But they ignored the drivers and leave them as standard and try to do everything in the crossover and cabinet damping. So you have complex filters all over the place, mechanical in the cab and electrical in the crossover. It is a problem that has polluted the hi-fi industry for a long time, and even now with far more driver choice some companies are still doing it. The antithesis to BBC design is Joe Acroyd of Royd fame. He knew what he was doing, tailor the driver and the cabinet to do the job, result musical speakers not hi-fi speakers, and he even made ported designs work reasonably well, which is a first in my mind.

A sadly missed designer who actually knew his subject, not engineers in white coats just engineering for engineering sake.

 

Sat in front of me (at work) I have JR149s (playing) - KEF T27 & B110

Also KefKit3 (not playing) KEF T27, B110 & B139

Both left home when the Harbeth HL1 MK4s arrived. Definitely a BBC speaker but not a KEF driver in sight, evidently that Mr Harwood thought there were better drivers to be had as well.

 

I've owned Studio 1's, LS3/5a's, JR149's, and LS5/9's, in that order.

Out of all of those I'd put the studio 1's in top position for all round enjoyment and general presence, closely followed by LS5/9's for the detail they deliver.

Gotta say though that despite all their good points none of them could quite displace my 12" Tannoy DC's.

 

Wash your mouth out - where's the soap!

That view is a little revisionist.
The chaps at the BBC research department probably did wear white coats and clearly did a huge amount of testing and measuring, but the research papers from the BBC archives clearly detail the many listening sessions used to test the theory and engineering. Moreover, the speakers created from that research were deployed in the control rooms at the BBC, with the real-time ability to check the reproduced performance agains the live performance. You could literaly walk from the studio into the control room and compare.

Many variation of the cabinet were produced, with aim being to move cabinet resonances to a point were they were least subjectively objectionable. They also set out to establish certain standards for audibility, establishing that listeners failed to reliably detect cabinet effects once the output from the cabinet was x db below the main speaker output. Objective and subjective processes working together as they should.

You can't eliminate cabinet effects - only move them around. A rigid medite box doesn't solve the problem, it just moves it. So it comes down to preference.

I like Royd speakers and many of the distantly related Rega models, but tiny and very light paper cone drivers and 3/4 inch plastic tweeters miss an awful lot of music and information, though they can certainly sound fast and pacey.
A number of problems arise from the Royd approach.
Firstly, tiny, light paper drivers in small 7 litre cabinets produce no appreciable real bass. You get upper bass harmonics and this combined with the lack of fundamentals is what gives the (entirely false) impression of bass speed and precision. It is an aural trick and quite different to how we hear real, live sound.
Secondly, the very simple crossover filters mean that the drivers are running outside of their optimum passband. Small dome tweeters really don't sound that great when running on a low order crossover at the typical crossover points used. Distortion rockets at the bottom of their range - it is very audible.

Care needs to be taken when describing the benefits of bass drivers driven without external crossovers. In these examples, the filter has most definitely not been eliminated. The driver still needs to roll-off and it can do so mechanically or electrically or both. In both cases you still have a filter - you've just moved it from the external crossover the the driver.
Bass drivers roll-off electrically due to rising impedance as frequency rises, they are inductive. Look at bass drivers suited to direct connection to the amplifier and you find high self inductance, so you've simply moved the inductance provided by an external coil to the speaker motor. Whichever way you go you've got filters.

On the ease of drive issue, all I can say is that my Quad 405 will drive Rogers Export Monitors until the cabinets fall apart. It will give rated output without any issue.
It certainly won't if you connect a modern speaker with ultra simple crossover and the now common 4 ohm bass unit.

I have a foot in both camps and can enjoy simple old ARs while also enjoying big old Spendors or Rogers. Just a different blend of compromises.

 

Is the ES14 an honorary BBC speaker? If not I'll shut the f**k up!

 

Sort of

Robin Marshall was a fan of the BBC designs (his old company was licensed to produce some of them) and there are reports that the ES14 was a modern take on the old designs.

In reality the design is very different, though there are some similarities in the presentation.

 

I remember an interview where Robin Marshall cited the Spendor BC1 as a major influence in designing them, he was a fan of that speaker, though beyond that there is very little in common between them conceptually.

Tony.

 

Robin was a BBC designer, was he not?

 

I was at the ITV studios a while ago and heard the 10 o'clock news go out live.

Some Rogers and Quads were doing a superb job!

 

Audiomaster IIRC, who were one of the companies licensed to build the LS3/5A. Not his design though.

Tony.

 

Thanks Tony.

This weekend I am going to hook up my dads mint Ditton 44s. Look a bit like BC1s

To my shame I have never heard a pair of LS3/5s.

 

The Quad amps turn up everywhere.

As a kid in the 80s I was lucky enough to do some extended work experience at a small recording studio in East London. Talk about a kid in a sweet shop!
405s lying around driving Tannoy LRMs and wall to wall Revox tape machines with either Dolby A or DBX processors.

303s are everywhere. I think they still use them to drive the train station tannoy systems via a special output transformer.............. and before anyone say 'that's all they are good for' ....... button it!

 

Er, heard 303s and 405s in my early AV days. Not bad as monitor amps at the desk..........beyond that........

 

My 303 gets little use and is only really here because i like collecting this stuff.

The 405 is much maligned IMO.
The 405/2 I'm using at the moment certainly doesn't have me wishing I was using anything else.

Many of them are shagged though, even if they still 'work'.
They run hot and there is no real ventilation so the old electrolytics would cook.
Give them a recap with good modern high temp caps and you might be surprised.

The self correcting nature of the dumping circuit tends to mask slow deterioration of the amp. It was designed to ensure a long and maintenance free service life but it also makes performance slip over the years a little less obvious IMO.

 

Funnily enough I was talking today to someone about new cases for 405s!

As to the sound, well they are Quads. Polite and refined with ok dynamics within their performance envolope. Sounded good with Tannoys in our studio way back in the 80s.

 

Ah.... I was checking the electronics catalogues last week for some perforated mesh to make a new cover for the 405. I like the existing case - looks classic - but a perforated top that looked professional should help keep things cool and extend life.

 

Its possible but at a, not small, cost.