Proac R2 Crossover Mod
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After playing about with numerous
system 'tweaks', I thought I'd take a look at possible component
upgrades for my speakers. A peek inside the box revealed that the ties
holding the inductors were loose, likewise the nuts holding the (cheap
style) connectors to the binding posts. The stranded (QED Audio) copper
cable was showing
signs of oxidation. For those interested, here is the circuit
Below is the original crossover and
decided to rebuild the crossovers with upgraded components and cable.
Since I was using the Goertz MI2(bi-wire) as speaker cable, I thought I
would use this internally
as well. This cable can be fairly inflexible to work with but its wide
convenient solder pads.
After searching and posting some questions at the
Asylum I decided on replacing the existing Solen caps with
Hovland Musicaps and using a power film resistor in place of the
standard wire-wound type (all values as original).
The original inductors were retained.
Here are the finished
Bass and treble circuits are on separate boards - so I could shoehorn
the new crossover
through the woofer cutout - and screwed to the backwall with some
'Blutack' in between.
The binding posts in the boxes are positioned right behind the bass
port making soldering
very tricky. I decided to retain the 'bolt on' connection(for the
moment). Use of the
Goertz cable eliminated the need for connectors, I used a paper punch
to make holes in the
Note: the 4.7uF cap was replaced with 4uF and .68uF caps - Wilmslow Audio,
were out of
4.7uF caps but supplied the aforementioned at the same price.
The heatsink on the film resistor is overkill (dissipates 20W!) - I
should have looked
closer at the catalog but what the heck.
Here is the new
crossover mounted in the box:
had an opportunity to compare my modded Proacs with a friends stock
factory pair - a slightly later build, but still the front ported
version. The sound of the two share more similarities than differences.
Nevertheless the modded pair had an edge in clarity and transparency
from the upper-mids to the highs that was quite worthwhile IMO. The
stock pair were a bit 'gray' sounding by comparison. My friend also
thought the bass was a bit more heft through my modded pair.
However both communicated the music with the typical R2 verve.
suggest that any R2 owner thinking of changes, firstly check for
connection tightness to the binding posts (inside the cabinet) and
loose components on the crossover boards. Also, be sure the drivers are
firmly bolted down - don't get silly though, you'll break something.
Then, instead of the wholesale rebuild I did, perhaps try replacing
just the tweeter caps and see what that gets you. Because of their
size, the Hovland caps I used aren't really convenient replacements if
retaining the stock crossover boards, so perhaps something like Auricap
or Ansar might be worth trying.
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