Epic CF-4 crossover issue.....missing a cap, and can't read rating of other speaker's cap!

[moray james]

100 volt rating is more than you need. How many SS amplifiers do you know of with 90 volt rails much less 100 volts? Even if you had an amp with rails in excess of 100 volts you are never going to use even half of that you would be run out of the room. A 50 volt rated cap would be fine for any crossover many use only 35 volt rated caps. These caps are not designed with loudspeaker applications in mind.

[G87]

45 minutes ago, moray james said:

100 volt rating is more than you need. How many SS amplifiers do you know of with 90 volt rails much less 100 volts? Even if you had an amp with rails in excess of 100 volts you are never going to use even half of that you would be run out of the room. A 50 volt rated cap would be fine for any crossover many use only 35 volt rated caps. These caps are not designed with loudspeaker applications in mind.

 

Ahhh ok well that makes things a lot easier! Thanks yet again moray. (I'm G871 on AK)

[glens]

2 hours ago, moray james said:

100 volt rating is more than you need. How many SS amplifiers do you know of with 90 volt rails much less 100 volts?

 

Not arguing that 100V caps are insufficient, but it would only take 50V rails, fully utilized, to get the cap seeing the 100V differential there.

[moray james]

 you don't see a lot of commercial speakers with 100 volt rated electrolytic caps in the bass section of the crossover. Can you even think of a popular SS amp which has 100 volt rails? Even with low efficiency loudspeakers a 50 volt rated electrolytic is the norm. Fact is that electrolytic caps are good for a least double their rated value and so even with peaks you just don't need a higher rated cap. If you want to use a higher rated cap and pay for that no problem. Don't make this out to be a problem for modifiers with limited experience when it's not. Even a 25 volt rated cap is fine to test out a network if that is all you have at hand.

[G87]

Next question - the schematic specifies that all caps should be +/- 5%. How important do you guys think that is in the LF network? All the caps I ordered for the HF network are +/- 1% or 5%. But the LF caps I ordered are +/- 10%. Is that too much deviation in the LF network or is that acceptable?

 

I was thinking on most speakers with a low crossover frequency from the woofer to the mid/tweeter, it wouldn't matter much for imaging....but since these woofers cross over at 1500hz (IIRC), the +/- 5% may be more important here.....

 

Whatcha think?

Edited June 3, 2019 by G87

[Deang]

I wouldn't lose any sleep over it. 

[G87]

Great, I won't. Thanks all.

[Oicu812]

On 6/4/2019 at 4:23 PM, G87 said:

Great, I won't. Thanks all.

 

I would suggest that you replace the resistor as well.  They aren’t that expensive, and yours looks a little toasty in the wire lead in area.  Look at your pic, and then look at wvu’s.  It’s the long white ceramic piece.

 

It appears to have gotten hotter than normal...

[Deang]

I agree with that.

 

This is why Bob and me recommend complete rebuilds. You don't know the history of the loudspeaker, and so don't know the actual condition of all of the parts without measuring.

 

This set may have lived in front of an old Phase Linear running at full tilt most of the day.

[G87]

On 6/5/2019 at 10:59 PM, Oicu812 said:

 

I would suggest that you replace the resistor as well.  They aren’t that expensive, and yours looks a little toasty in the wire lead in area.  Look at your pic, and then look at wvu’s.  It’s the long white ceramic piece.

 

It appears to have gotten hotter than normal...

 

I noticed that! Explains the one 'missing' cap and the cap with split coating on the other speaker. 

 

They'll definitely be getting some Mills resistors soon.

 

On 6/6/2019 at 9:10 AM, Deang said:

I agree with that.

 

This is why Bob and me recommend complete rebuilds. You don't know the history of the loudspeaker, and so don't know the actual condition of all of the parts without measuring.

 

This set may have lived in front of an old Phase Linear running at full tilt most of the day.

 

I got these from the original owner who ran them with a BIG Denon receiver that he bought at the same time. I don't remember the model number but it was rated at 170wpc. (had either 5 or 7 channels) He said he was in his twenties at the time, and didn't go in to details, but I think the crossovers tell the story pretty well.