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Crossover caps?

Gregory

Gregory

Soundco Kid
Looking for 25uF and 50uF electrolytic caps, rated at 100V and suitable for a high-quality crossover network. The schematic says to use `low ESR´ but what is low? Would it be fair to assume these would be NP, as the photos show caps labeled `100 VNP.´ There are some axial Vishay/Sprague available that are 25uF and 50uF, 150V. http://www.mouser.com/catalog/catalogUSD/641/756.pdf

http://www.mouser.com/catalog/specsheets/tvaatom.pdf

Here are some Low ESR, NP at 22uF and 47uF, 100V, 10% http://www.mouser.com/catalog/catalogUSD/641/760.pdf


Recommendations please?


-Gregory
 
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Parts Express (parts-express.com) has a large selection of crossover caps. 'Lytic and film. Yes, non polar.

Murray
 
dshoaf said:
Why not consult one of the designers? Contact Roger at www.rogerrussell.com or Google the name. He has been very helpful to me.
Click to expand...


Yes.. I know Roger fairly well and sent him several XR6 related emails in the past few weeks. McIntosh Parts has the caps in stock for 7 bucks each but I thought someone could advise on the same parts [as Mc would ship] at direct prices. I need two of the 25uF and four of the 50uF NP.


-Gregory
 
MX117.MC7150 said:
Check out Michael Percy Audio. He will let you spend about as much money as you want on boutique caps. He does include a fair amount of information on his various offerings. Lots of builders over here http://www.diyaudio.com/forums/loudspeakers/ and in the AK speaker forum with plenty of experience.
Click to expand...

Expensive over there!! Could always order them from McIntosh Parts. Thought that with some help from AK members I could order the correct parts direct.


-Gregory
 
The NP caps from Parts Express work fine but always run the best PE poly cap, in parallel. .1 mfd works good and this will sound nice as I have used it many times. Check the value of the NP caps with a capacitance meter before using them and match in the two crossovers for best imaging. If you need 2 of one value order 6 or more so it is easy to match 2.

Thanks,
Ron-C
 
Gregory said:
Yes.. I know Roger fairly well and sent him several XR6 related emails in the past few weeks. McIntosh Parts has the caps in stock for 7 bucks each but I thought someone could advise on the same parts [as Mc would ship] at direct prices. I need two of the 25uF and four of the 50uF NP.


-Gregory
Click to expand...

It's not easy finding "high ESR" caps nowadays because of improved materials and techniques. Modern "low ESR" caps would be considered VERY low back in the days when the XR-6 was made.
 
ron-c said:
The NP caps from Parts Express work fine but always run the best PE poly cap, in parallel. .1 mfd works good and this will sound nice as I have used it many times. Check the value of the NP caps with a capacitance meter before using them and match in the two crossovers for best imaging. If you need 2 of one value order 6 or more so it is easy to match 2.
Click to expand...

So then.. order 0.1uF poly caps and solder them in parallel with (on top of) the electrolytic? I may PM you on this trick unless someone can provide an example. Would they be considered `bypass´ caps?

Can someone expand on this scheme?


Thanks,

-Gregory
 
25uf and 50uf Poly caps would be hung and expensive!!
It's MUCH cheaper to parallel a smaller Poly bypass cap, with your electrolytic caps, to get good sound quality.

Good luck & have fun!!
Steve
 
Greg,

Yes, you would parallel the two caps in bypass fashion. The value of the two caps would then add together. This would also allow you to maintain the original parts board spacing.
I will not say that using big polys is not an option but they will not fit in the stock crossover location.

Thanks,
Ron-C
 
While we're on the subject.. how about replacing all of the caps on both crossovers? The other three caps are Mylar from the late 70s. What would you recommend as replacements for THESE components?

Here's a photo of both boards. One is 1-1/2 to 2 years newer that the other:

XR6_crossover_CD1635_1634.jpg



Here are the original caps:

Code: 
C1      Electrolytic      50uF      100V
C2      Electrolytic      25uF      100V
C3      Electrolytic      50uF      100V
C4      Mylar    10%      6uF      100V
C5      Mylar    10%      2uF      100V
C6      Mylar    10%      3uF      100V


-Gregory
 
Greg,

here are a few shots of how the PE caps would look. These are ESS AMT-3 crossovers that sound fine.
I also recommend new Mills resistors as your originals may have drifted.
You can have the poly on the top or sides of the NP electrolytic. If you want to replace the mylars with polys check the size difference first.
You should have a hot glue gun to secure everything down and damp vibration of the parts.

Thanks,
Ron-C
 

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ron-c said:
Greg,

here are a few shots of how the PE caps would look. These are ESS AMT-3 crossovers that sound fine. I also recommend new Mills resistors as your originals may have drifted. You can have the poly on the top or sides of the NP electrolytic. If you want to replace the mylars with polys check the size difference first. You should have a hot glue gun to secure everything down and damp vibration of the parts.
Click to expand...

Ron.. I received a shipment of NP caps from PE and measured with DVM. They are running 13.98% high. It's not certain if the meter Cal is out, or the values are high. In the 25uF case, I ordered 22uF and they tested out 25.08uF (ave) which is 13.98% high. On the 50uF batch, they tested out 57.0uF (ave) which is also +13.98%.

I may order another batch of 47uF to get a net result of 53.6uF if the 13.98% holds true. To get 50uF at the error rate of 13.98%, they would need to supply 44uF caps. As said already, it could be the DVM, however the SMALL caps are <1% which is their spec actually.


Capacitor analysis spreadsheet: XR6 cap analysis.xls


What do you think about that?


-Gregory
 
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It is always best to measure new caps. I think your meter is off in this case though. 5% out I can believe but if they all read high. What did the old caps measure? As these old caps wear they tend to read high so they should be higher than the new ones on your meter.

Thanks,
Ron-C
 
It is always best to measure new caps. I think your meter is off in this case though. 5% out I can believe but if they all read high. What did the old caps measure? As these old caps wear they tend to read high so they should be higher than the new ones on your meter.

Thanks,
Ron-C
 
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