Thread: JR 149s
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Howard Stone Howard Stone is offline
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Default JR 149s

On Thursday, 6 June 2019 16:22:32 UTC+1, wrote:
On Wednesday, June 5, 2019 at 1:12:27 PM UTC-4, Howard Stone wrote:
What are people's experiences with JR 149s?

I have a pair being driven by a Quad 520 . The sound is not very
satisfactory -- it sounds "amplified" I wonder if people have
found a really successful amp for them.

Someone I know loves the sound he gets out of them with a leak
ST20. Thats 10W per channel. But it turns out that he listens
very vert close and very quietly. I want to be able to listen
in a smallish room -- 15'x15' -- though not to loud music --
a harpsichord or a handful of voices max or a few string instruments
max.

And then there's the question of positioning. Does anyone think
that the wall brackets Jim Rogers produced are a good idea for
the sound? I have mine on stands but close to a wall, 10'apart.

Oh my source is an old Deltec Bigger Bit DAC; no preamp.

I'm toying with the idea of getting a PASS Aleph 30 clone for them.

It may be that these speakers were designed for near-field
monitoring and it's just not possible to get a satisfactory
room filling sound from them.


The JR's are very much based on the BBC LS3/5a design,. It uses the
same KEFB110/T27 set of drivers and a somewhat similar crossover.
Both of these drivers are VERY good, but especially the B110, it's
a 5" mid/woofer, perhaps on the best every made, but it's still
only a 5" mid/woofer.

Now, as to the design goals for the original LS3/5a, I would refer
you to the original design brief,

"There is a need to monitor sound programme quality in
circumstances where space is at a premium and when head-
phones are not considered satisfactory. Such circumstances
include the production-control section of a television mobile
control-room, where the producer responsible for the overall
production of the programme needs to monitor the output from
a sound mixer but at levels lower than those used for mixing."

Hardwood, Whatton and Mills, "The Design of the Miniature
Monitoring Loudspeaker Type LS3/5A", BBC RD 1976/29, pub.
Research Dept., Eng. Div. British Broadcasting Corporation,
1976 October

So, imagine a large trailer pulled up to a remote venue, and said
trailer is divided into several "rooms", one of which is for the final
monitoring of the "programme". Said trailer might be 10-12' wide, and
the room might be 8-10' long. The producer might be sitting in front
of a console, and as a result the producer listening might be sitting
all of 5-6 ft away from the speakers, which themselves might be 4-6 ft
apart.

This is the scenario the speakers were designed for. Your friend's
scenario is much closer to the design intent than yours.

As to what amplifier is "best", I think that is, at best, a tertiary
issue. The venue and use scenario is the dominating set of limiting
factors. I would posit, and be willing to back it up objectively,
that, used in the right way, it makes little if any difference whether
you're using it with a quad 520 (100+ watts/ch), a Leak, a Pass
or whatever up to the level common to what all of them can produce
without distortion.

The point being that the speakers were intended for moderate monitoring
in a small venue.

What subsequent uses were invented by the high-end, and claims about
the suitability in those scenarios, is another question altogether,
and, like much in the high0-end, may not be constrained by inconveniences
like facts, physics or reality.

As usual.


I am afraid that you are right, Mr Pierce. Such a shame!