In article , Tat Chan
wrote:
Jim Lesurf wrote:
Later on I bought a pair of 63's and used them as my main speakers for
about 20 years. Only recently switched to using 988's and have added a
sub to help move the air at LF.
Jim, what sub are you using with your 988s?
MJ Acoustics MJA Pro 50. Relatively cheap and cheerful compared with some
of the subs on offer.
I chose this because - at the time - I was far from convinced that I'd end
up deciding that a sub was worthwhile. I am also using quite a small room
and I only listen at relatively low levels, so high power probably wasn't
really needed. Hence I would not say the above was an 'optimum' choice, or
would suit anyone else.
So I decided to try the Pro 50 as an experiment/gamble at modest cost.
I was informed that it is hard to find a matching sub for ESLs due to
the nature of ESLs (dipoles? planars?)
Yes and no. :-)
I suspect that there are problems with matching a sub with almost *any*
decent speakers and room. I certainly spent many weeks fiddling about with
the settings and positioning. Giving myself longer an longer periods
between 'adjustments' to get used to the results before experimenting with
a change.
The 'problem' with ESLs is, I think, that they lack colourations and
cabinet resonances, and have low distortion. Hence any of these from the
sub may be more noticable.
The dipolar nature at LF mainly means that the ability of the ESL to drive
the room falls. But it does this in a fairly 'good natured' way as it
decouples itself from the ability change the pressure in its surroundings.
I don't know if it would have been quicker/easier to get decent results if
I hadn't been using ESLs. or in another room. I assumed in advance that
getting speaker postions, etc, satisfactory was likely to take a lot of
patience. :-)
FWIW in the end I concluded that adding the subs did indeed give better
results. The effective hand-over point is well below 100Hz. I'd estimate
somewhere around 40-50Hz. The sub is currently placed up against the wall
behind one of the ESLs which are a bit over a metre from the back walls,
and angled in both the vertical and horizontal so that the axies cross just
in front of my nose. :-)
The main 'defect' so far is that there is a room resonance somewhere around
40Hz (IIRC). The ESLs didn't excite this very strongly, but a sub does as
it can pressure the room. Hence I have been considering buying a
replacement sub that has its own notch filter to cut down the room's first
non-zero resonance. But ignoring this, the Pro 50 seems to work nicely. If
I switch off the power amp driving the ESLs the only sound from the Pro 50
is the occasional deep note/noise with no obvious colourations or
complaints at higher frequencies.
I also use a modified Quad 34, which lets me either increase or cut the LF
levels where desirable. Some films and TV broadcasts have excessive LF,
whereas some classical music CDs are a bit light on LF - particularly old
EMI recordings from the days they were terrified of 'the jumping stylus'.
:-)
You have reminded me that I should re-measure the setup as I have made
various minor changes since I last did that. :-) That said, my previous
experience has been that having - by measurement - got a roughly 'flat'
transition - I then tended to lower the sub level a bit. Not yet sure if
this says something about what is recorded, or my taste, or it being due to
the room resonance...
Overall, I'd say it was well worth while experimenting with a sub to go
with ESLs. You need to spend time adjusting and re-positioning, but the
results with things like piano or orchestra can be good. However with the
main hifi I used for many years I got similar results by using a modified
low bass contour applied using a modified Quad 34. This does not go as
'deep' as the sub, and means you have to avoid high levels, but the results
are more 'coherent'. All depends on the room, though. If interested, the
modified 34 may be a better option.
Slainte,
Jim
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