In article
,
molipix wrote:
I'm building up a sound system for our living room using second hand
parts. I would like to keep things as small and unobtrusive as possible.
So far I have a Cyrus II amp - this has outputs for one pair of speakers
(rated at 8 Ohms). My plan is to connect two small bookshelf speakers
like the Tannoy Revolution R1s and add a subwoofer. The options as far
as I can see a

1) connect a passive subwoofer in parallel with the bookshelf speakers
2) connect a passive subwoofer in series with the bookshelf speakers 3)
connect a subwoofer with a built in amp

I think 1 risks blowing the amp, 2 could affect the sound quality so I'm
leaning towards 3 but this seems a bit of a waste of the power available
from the Cyrus II. Any opinions?

Various things strike me about (1) and (2).

Firstly, that you might not be able to get enough power. Mainly because a
sub will tend to be inefficient unless you are going to use a large
cabinet.

Secondly, that getting the levels to match from sub and main speakers may
well be difficult (without losing even more power). In particular I'd
expect a sub to need somewhat more power than bookshelf speakers - but you
don't say what sub you plan, so hard to say more.

Thirdly, that (2) would probably upset the responses of the bookshelf
speakers. i.e. as you say that may well cause problems with the results.
Again you say nothing about any passive crossover filters you would be
using, so hard to say more.

Finally, that any passive sub may well need you to experiment with
filtering to try and correct the sub response, again risking wasting power
if done between amp output and speakers.

To make life easy I'd recommend (3) or if you wish to experiment with
'DIY'...

(4) use another amp to drive your sub. Take the outputs from the 'record
out' of the Cyrus and use a low-pass filter between that and the extra
amplifier. You may find a cheaper high power amp from an electronics
supplier may do for this. Something along the lines of a module or kit.

or

(5) If you don't need high power, add a filter into the tape loop that can
extend the response of the speakers at LF. This is obviously to be done
with caution, though, as it would rapidly run you into trouble if you want
loud sounds down in the sub region.

However I guess the choice will depend on how much time and skill you can
devote to trying something. Again, that isn't clear from what you write, so
I can't comment.

Slainte,

Jim

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