Crossover - Suggestions for Modifications

[chrism]

Got a cheap pair of Wharfedale speakers and fancied ago at improving the quite poor quality looking crossovers.

Be really grateful if anyone could offer suggestions about modding them or even swapping them out for something a bit better.



Regards

Chris

[danilo]

Replace the Blue electro caps with Film types ? Leave all else alone.. imo, improvements there will not be comensurate with cost/effort.
The 15Uf Low Frequency cap will be 'large' in a film/foil version though and of Minor advantage to upgrade .
The other one is a must do.

[chrism]

Thanks Danilo,

Any suggestions for a type of film cap - low cost would be good. Anything on good old ebay would be great.

[Reffc]

They're not that poor quality, it's just a simple second order two way filter. I would advise against swapping the bass cap out for a poly...they will have been voiced with the ESR of those bipolars taken into account. If you must change one for a poly, change the HF series cap as at higher frequencies, the ESR differences start to reduce and have less of an impact. Like for like with the Bass, a simple solen 8uF for the HF perhaps bypassed with a higher qualiity 0.1 or 0.2uF poly.

Don't expect night and day improvements as the speakers are what they are, but if these are factory originals (they dont look that old tbh) then it will help a bit, if only by reducing ESR which increases as electrolytics dry out. Forget "Foo" caps for this design as the values, in this instance are way more important than the brand.

[chrism]

Thanks for the help. Any benefit just adding a .1uf poly bypass on its own? The electrostatics are bipolar and not sure if bypass would be OK with them?

[danilo]

Yess you can add a reasonable value 5 to 10% Bypass cap to the hf one. Possibly might even help.
Just as easy with happier results to replace the cap entirely though.
Splurge the ~3$ each :-)

[Arkless Electronics]

It won't make any difference but can't harm....

[chrism]

Really struggling to find any low cost 8.2uF poly caps to try instead of those HF electrolytics - they appear to be more than I bought the Wharfs for. Any suggestion were I can buy two to have ago would be really appreciated.

Regards

[walpurgis]

Use 8uF. The difference is so miniscule it won't matter. It's a more common value and should be easier to find.

[walpurgis]

Some here.

http://www.ebay.co.uk/itm/252523905970?_trksid=p2060353.m1438.l2649&var=551425505474&ssPageName=STRK%3AMEBIDX%3AIT

http://www.ebay.co.uk/itm/201204855959?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Personally. I have no objection to using reasonable quality electrolytics.

[Reffc]

Just use Solen polys. Cheap as chips and good enough for megabucks speakers like Verity Audio loudspeakers. Available from Falcon Acoustics.

[danilo]

Really struggling to find any low cost 8.2uF poly caps to try instead of those HF electrolytics - they appear to be more than I bought the Wharfs for. Any suggestion were I can buy two to have ago would be really appreciated.

Regards

I too had all kinds of trepidations when I first started fiddling with crossovers.. back when Electricity was New.
More than likely those 8.2 uf Electros you are concerned with are anywhere near their printed values.
Prolly anywhere betwixt 5 uf and 10 uf.
Unlikely to be consistent between crossovers either
A cap meter is educational in this. But also another gizmo to clutter ones' workspace And misplace.

As above: Buy a pair of Solens and be amazed by their effect.

[chrism]

Thanks to everyone for the advise and encouragement.

I have taken the xovers out of the cabinet and looking for a couple of small boxes to mount them into. Used a bit of spare Avondale black link to rewire them to the speaker as well. Bought two cheap polyethylene caps (8.2uF) from Blue Aran for the high frequency and they are sounding different. A bit clearer on highs and more precise sounding than before - think that the swap out is a keeper.

My eye is now looking to the other elcap on the low frequency and against good advise thinking about a poly there as well! Not sure about this tho as don't want to reduce bass response at all.

Regards

[danilo]

Poly is a Fine substitute for the LF electro.
However a passable Flim Foil will be rather large. Fitting could be an issue.
Also it's resistance should approximate that of the original Electro.
Measure it and the New film cap. Best measure both Crossover's LF electros as their values have likely age drifted
and there is also good chance they were different even when new
Average the measured values. Add a series resistor to the film cap to make up the difference.
No worries re losing Bass from this

You might also consider fitting a Line level crossover IF you have an 'extra' amp.
Cheap and easy ish :-)
http://www.t-linespeakers.org/tech/filters/passiveHLxo.html

Cheapish speakers seem to benefit most from Biamping/line level crossovers.
That should keep you busy.

[chrism]

So far so good and really like the sound changes that the low cost poly caps have brought. Much cleaner sound than the elcaps that were in previously.

Looking at the ceramic resistor - 5w 3.9 ohms and 10% tolerance I think and wondered if there was any mileage swapping one this out as well? Not sure what type to go for - mills?

Added a few photos - just got to find / make a couple of boxes next for the xovers and have ordered a few low cost sockets as well.

[walpurgis]

Nothing to be gained by changing the resistor.

Have a look for plain wood boxes on eBay.

[danilo]

Great! Surprisingly those LF caps seem as way small, at least for 15uf ers. Good find.
Have a 1$ store in your world ?
Here they typically stock a variety of decently built wooden boxes (of 1/8" light plywood usually) in a variety of sizes /shapes
These make for quite good homes for diy Audio bits... sometimes even permanent ones.
Easier than trying to find a usable cardboard box.