Alesis Monitor Ones Crossover Cap Replacement

[Andybot]

Hi,
im going to change the caps in my alesis monitor ones and i was looking for suggestions on what brand or brands to replace them with. Right now they have KSC 50V non polar electrolytics of values 24,16 and 5 mfd.
Thx

 

[emrr]

Good question.  I still have a pair that need crossover rebuilds.  I found long term vibration sheared the resistors off on several occasions, and it seems worthwhile to shock mount the whole crossover to damp microphonics. 

 

[JohnRoberts]

Film caps are better but huge in those values. You might consider paralleling electrolytic with film, but even a 1/10 capacitance film cap will not be small.

JR

 

[Andybot]

Im not sure size is an issue, i could fit a good size cap in their.
A

 

[emrr]

A 24 mfd film cap looks like a stick of dynamite, a 5 mfd sorta like an M-80. 

 

[Andybot]

Are you trying to blow up my speakers?

 

[ricardo]

Bi-polar capacitors are much improved in the last 30 yrs.  In the smaller values, eg 5u, you'd be hard put to tell the difference between a good one and a Golden Pinnae film.

Unfortunately, the DIYer doesn't have access to cap makers.  The 2 things to look for are Lo ESR (they may be advertised as Low Loss) and Size.  You are looking for a measured 1kHz Q of 25 or greater.

The good Bi-polar Electrolytics are the same size as a Golden Pinnae film.  They were also always made to special order which isn't much help to the cap swapping brigade.

Why do you want to change your caps?

 

[Andybot]

Id like to change out the caps  to see what difference  higher quality caps will make  but i also have an intermittent problem that follows the crossover and effects the tweeter. Ricardo, by bi-polar do you mean not polarized?
Thx

 

[ricardo]

i also have an intermittent problem that follows the crossover and effects the tweeter.

Resolder and check all the solder joints in the treble section

Ricardo, by bi-polar do you mean not polarized?

You call them 'non-polar electrolytics'.  The only one you can sensibly swap is the 5u for a film.

When you take the old one out, measure its Q so you can determine its ESR.  If you want the speaker to sound the 'same', add a series resistor equal to the ESR.  If not, you will get extra HF 'clarity & definition'.

Don't buy any bi-polars unless they are physically bigger than the originals.  And measure old & new for ESR before deciding which to leave in.

 

[CJ]

after the cap job remember to stuff socks in the speaker ports to get rid of that low end boost,

 

[Andybot]

my mixes are stinky enough as it is.

 

[emrr]

If you have an intermittent, it's probably the same thing I've seen:  resistor or cap legs that are sheared off from vibration, and making passable contact most of the time. 

I rebuilt a set recently, and used a film cap for the series tweeter connection.  With all new caps, and that one upgrade, they are entirely different than before, much clearer and open.  Fresh caps with lower ESR really make a difference here. 

 

[lassoharp]

Need to check one of mine soon.  Seems to be losing some high response.

 

[Andybot]

I never thanked Ricardo for his input, how rude.
Thx Ricardo and everyone else
Thx