Audax HD-3P Gold Dome replacement - Page 4 Final Listening

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Audax HD-3P Gold Dome replacement
Page 2 Crossover
Page 3 New Strategy
Page 4 Final Listening
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Final listening

When the owner arrived, he was ushered into the listening room to make sure all was well. Initially I undid the ‘correction’ I had made to the bass crossover to make sure that this didn’t destroy the character of the speaker that he had been used to.


Initial listening was exceptionally positive. More than just restoring the original treble response I had, according to the owner, apparently improved the clarity and detailing of the treble. The other major surprise was his claim ‘at last, a good, precise stereo image’, which unsolicited comment backed up what I thought about the phase relationship of the two upper frequency units.


What about the natural realism of the sound?’ I asked after a few tracks had passed. ‘Not bad’ came the reply. ‘I’d like to try an alternative, if you don’t mind’ I proffered. That was the point at which I added the 18uF back in. A few more tests of ‘with’ and ‘without’ and the owner proclaimed himself more than satisfied with the more realistic results of adding the 18uF.




Actually, because he was going to reconstruct the crossovers with the new components and values I’d devised, I suggested that he took a selection of SONIQS polyprop capacitors with him in order to optimise the performance in his own room. It’s one thing to do a quick lash up for an impromptu change, but another to actually settle down and listen to that change over a longer period of time. At the time of writing, the 50uF plus 18uF is still the firm favourite, but there’s nothing wrong with experimenting if you want to try different values here.



If you want to improve further aspects of the performance of the crossover there are several components that you can upgrade. This applies whether you continue to use the original Audax gold dome piezo treble units or the SEAS Millennium.


Naturally it is worth changing all the capacitors to high quality polypropylenes such as the SONIQS PXX and SAX types we use in our own crossovers. This is particularly true of the 50uF capacitors in series with the midrange unit. Those looking for the best quality may wish to use SONIQS SAX capacitors throughout, but a 50uF value in this range is so large as not to be believed! So the cunning plan is to use a 47uF PXX with a 3.3uF SAX in parallel with it to give the required 50uF.


If you like the sound of the 18uF across the bass crossover 50uF then you don’t have to change the latter as the 18uF bypass capacitor is big enough in value to practically swamp the performance of the original electrolytic 50uF. I’ll leave that decision up to you. In this owner’s speakers he had already changed the electrolytics to polyprops so the decision was already made.


Other than that, the treble level can be adjusted slightly up and down by varying the initial series resistor. I found that 0.68 Ohms gave superb integration and meant that this 3 way design gelled into a big, spacious, music player where none of the drive units stood out on their own but all worked together. If you want more sparkle then try a 0.47 Ohm or, conversely, if you want your KLS3 Golds to sound warmer try a 1 Ohm.


What we’ve ended up with here is a reworking of the KLS3 Gold, previously in Mark II form so I guess, with the SEAS Millennium treble unit and crossover revisions we can genuinely call this KLS3 GOLD Mark III.








What you will need to replace your Audax HD-3P Gold Domes with the SEAS Millennium.


2 x SEAS T25CF002 Millennium treble units


For the Treble crossover -

2 x 0.68 Ohm resistors

2 x 4.7 Ohm resistors

2 x 4.7uF Polypropylene capacitors

2 x 0.11mH air core coil


For the Midrange crossover -

2 x 8.2uF polypropylene capacitors




For the Midrange Crossover -

4 x 47uF polypropylene capacitors

4 x 3.3uF polypropylene capacitors


For the Bass crossover -

2 x 18uF polypropylene capacitors

Comments (1)
Speaker Upgrading
1Tuesday, 31 July 2012 08:36
Greg Ferrari
A very good article with the detail I prefer. The principles of how to improve the old speakers with well known drives units to meet the current quality of the best digital sound is now a necessity to anyone wanting to retain old speakers and get fantastic sound

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