BC1A in BBC Studio

LS5/9 with matching HH amp from BBC Scotland.

very rare pictures timtube thx.

my HH ELECTRONIC PROFESSIONAL POWER AMPLIFIER AM8/17

The HH amp made to drive LS3/5A - AM8/12

LS3/5A with AM8/12 in traveling case.

mine

I never had a chance to hear the AM8/12 driving LS3/5A.

How does it sound?

Rogers的創辦人Jim Rogers在60年代尾和BBC合作研發BBC Monitor LS3/6，於1969年推出了Rogers BBC Monitor Speaker LS3/6，也就是最早被商品化的BBC Monitor Speaker。另外Spencer Hughes於同年研發出Spendor BC1，也是最早被商品化BBC Monitor之一。
------------------------------------------------

Alan,

That may not be totally correct. The BC1 and LS3/6 shared the same origin and hence the similar design and outlook.

Please refer to the letter from Spencer Hughes, Founder of Spendor, at the bottom of:

http://hometheaterreview.com/-spendor-bc1-loudspeakers-reviewed/

Dear Tim

Thank you for reminder. Quote information from vintage magazine as follows:

Rogers BBC Monitor loudspeaker
Price: L89.35, stand L6.96 extra. Manufacturer: Rogers Developments (Electronics) Ltd., 4/14 Barmeston Road, London S.E.6 3BN.

THIS new loudspeaker is the result of work by Jim Rogers in conjunction with the BBC
Research Dept. to produce a commercial version of a monitor speaker developed by Mr Harwood and described by him in three articles in Wireless World in March—May 1968.

Normally one associates the word "monitor" with a loudspeaker of professional standards, capable of covering an extremely wide frequency range with excellent transient response and handling large powers. Such speakers are physically large and usually of uninteresting appearance, sound quality being of paramount importance. In the BBC design, the system is housed in an attractive, dense teak enclosure with a neat dark grille cloth. It is of relatively small dimensions, and was developed for use in the smaller studios or for very high quality domestic conditions.

To achieve these objectives has taken the BBC Research Department years of patient study into the behaviour of loudspeaker cone structures and materials. Whereas in the majority of cases a loudspeaker assembly consists of mass produced units, but with reasonably tight reference standards, the Rogcrs/BBC bass unit is wholly hand made. It uses a gravity cast aluminium chassis carrying a powerful ceramic magnet, and a special hand constructed plastic diaphragm with a plastic roll-surround. Each unit is measured individually and then hand doped to meet a tight frequency calibration. This is a particularly skilled technique of loading the diaphragm at specific places with a rubberised dope which, though it does not materially affect the frequency response, improves the self-damping and reduces colouration.

Whereas the basic BBC Monitor design LS3/6 is followed, and made under licence, it was modified to include an ultra-high frequency unit with precision crossover. Although the middle and high frequency units are purchased from other high quality manufacturers, Rogers engineers still check each unit against a rigid go/no go specification.

Before the BBC granted a licence to Rogers Developments Ltd. to manufacture this design, they had to be assured that the Company had the skill and measurement facilities to ensure precise duplication of models for, under ideal conditions, pairs of loudspeakers used for stereo SPECIFICATION AND TEST RESULTS ROGERS BBC MONITOR LOUDSPEAKER should have identical characteristics. To achieve this end, Jim Rogers purchased the appropriate Bruel & Kjaer automatic loudspeaker response measuring apparatus, and built a medium-sized anechoic chamber some distance from the factory.
Whilst many multi-unit domestic systems have relatively simple crossover units coupling the bass, middle and top frequency units together, the BBC specification lays down very precise details of the inductors, capacitors etc. and their tolerances. A good example is the matching of the electro-acoustic conversion efficiency of the bass unit to the other two units. Slight differences in efficiency can make the system sound bass light or bass heavy. To overcome slight variations in the doping of the bass unit, a low-loss auto-transformer is used with a number of 1 dB tappings. Thus, when the system reaches the stage of final testing, the performance between the units can be balanced to meet the BBC specification. After final testing, each complete speaker is individually calibrated and its calibration curve supplied to the purchaser.

Agree with Tim that they are similar design and their outlook are also very much the same. As what I know the Rogers BBC Monitor and Spendor BC1 still has slightly difference on unit, as Rogers BBC Monitor is using Celestion HF2000, but Spendor BC1 is using Celestion HF1300.

Rogers LS3/6 and Spendor BC1 early blue alnico
have different sound according to my test.

BBC Studio Monitor Speaker LS3/6 and other models(15)

timtube

AM8/12 driving LS3/5A sound very flat and a bit thin. I still prefer tube but AM8/12 still very good compare to most solidstage like Quad 405 or Naim intregated.

AM8/17 hsd better control over LS3/5A very flat and powerful.

Early BC1 with AM8/17

Alan,

I think your article from vintage magazine was probably written from a commercial/marketing angle.

Given that Spendor has to pay royalty to BBC for each BC1 sold and similarity between LS3/6 and BC1＜ the letter from Spencer Hughes probably tells a more accurate story of BC1 and LS3/6 imho.

I see...!

Dear Tim

FYI, the Spendor BC1 and Rogers BBC monitor look very much the same, but their actual sizes are slightly different. The size of Rogers BBC monitor is 25" x 12" x 12", but Spendor BC1 is 25" x 11-3/4" x 12". On the other hand, the position and shapes of Bass reflexion port are also different too...!

Best regards
Alan

...

...

...

system