View Full Version : Crossover caps?


Gregory
05-17-2010, 12:38 PM
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

skippy_ps
05-17-2010, 01:27 PM
Parts Express (parts-express.com) has a large selection of crossover caps. 'Lytic and film. Yes, non polar.

Murray

MX117.MC7150
05-17-2010, 01:53 PM
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.

dshoaf
05-17-2010, 03:54 PM
Why not consult one of the designers? Contact Roger at www.rogerrussell.com or Google the name. He has been very helpful to me.


Cheers,

David

Gregory
05-17-2010, 04:21 PM
Why not consult one of the designers? Contact Roger at www.rogerrussell.com or Google the name. He has been very helpful to me.


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

Gregory
05-17-2010, 05:01 PM
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.

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

Gregory
05-17-2010, 05:04 PM
Parts Express has a large selection of crossover caps. 'Lytic and film. Yes, non polar.

Murray

Yep.. NP they are. PE is el' cheapo.. and that's where I bought the 8 ohm loads that reviews described as stable. ;)


-Gregory

Kevin M.
05-17-2010, 06:18 PM
Just curious, what kind of crossover are you doing?

Gregory
05-17-2010, 06:38 PM
Just curious, what kind of crossover are you doing?

At the risk of posting too much.. it's a recent thread: XR6 Isoplanar Loudspeakers (http://www.audiokarma.org/forums/showthread.php?t=297942) See Part - 3 of that series.


-Gregory

ron-c
05-17-2010, 10:51 PM
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

jwalker
05-18-2010, 01:07 AM
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

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.

Gregory
05-18-2010, 12:23 PM
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.

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

gearhound
05-18-2010, 12:27 PM
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

dnewma04
05-18-2010, 01:40 PM
I'm not sure what your budget for caps is, but if you need a pair of 25 uf and a pair of 50uf, you'd probably be looking at a bit over 30.00 shipped at PE for quality caps.

http://www.parts-express.com/pe/pshowdetl.cfm?PartNumber=027-438
http://www.parts-express.com/pe/pshowdetl.cfm?PartNumber=027-443

ron-c
05-18-2010, 08:12 PM
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

Gregory
05-18-2010, 10:20 PM
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:

http://home.comcast.net/~mc_audio/XR6_crossover_CD1635_1634.jpg


Here are the original caps:


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

ron-c
05-18-2010, 10:31 PM
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

Gregory
05-26-2010, 06:38 AM
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.


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 (http://home.comcast.net/~mc_audio/XR6_caps_analysis.xls)


What do you think about that?


-Gregory

ron-c
05-26-2010, 07:40 AM
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

ron-c
05-26-2010, 09:58 AM
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

Gregory
05-26-2010, 12:51 PM
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.



I'll bring in a few an measure them on the Fluke, then compare to the readings at home. Meanwhile I've ordered some 47uF NPs. Since the crossovers easily come out of the cabinet.... well let's not go there right now. :no:

Will be posting some photos of the rebuilt crossovers this weekend.


-Gregory

Gregory
05-28-2010, 09:32 AM
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.



Ron.. I haven't yet removed the old caps from the network (crossover) boards. That will happen this weekend, possibly even tonight. Have measured several other newly purchased caps.

The ACCURACY of the DVM in Capacitance mode for various ranges is:

4.0nF ... not specified
40nF ... +/-3%
400nF ... +/-3%
4.0uF ... +/-3%
40uF ... not specified
100uF ... not specified

So it's questionable above 4uF.


-Gregory

Gregory
05-29-2010, 08:33 PM
The Caps and resistors have been removed from the crossover boards.

I've also been able to measure, factor out errors and select matched PAIRS of caps from a batch. Here are examples.. two pair for each batch, one pair low and one pair a high.

http://home.comcast.net/~mc_audio/50uF_NP.png http://home.comcast.net/~mc_audio/22uF_NP.png


Question

Since the 22uF caps above are 3uF lower than the schematic value of 25uF, what's the best way to INCREASE by 3uF? Add a 3uF NP in parallel? Add a 3uF Poly cap in parallel? In that case, should there still be a 0.1uF bypass cap?


-Gregory

4343
05-29-2010, 09:08 PM
I'm not sure what your budget for caps is, but if you need a pair of 25 uf and a pair of 50uf, you'd probably be looking at a bit over 30.00 shipped at PE for quality caps.


I found these sound nice:
https://www.partsconnexion.com/capacitor_film_axon.html
And they are half price.
Since it's a one time deal, the values are not all there, they do have 24 and 50, but the 1.0 you would need to make a 24 into a 25 is out of stock already. I had to buy lots of 50's to make 100's for my biased networks when they ran out of 100's... (I used 4 50's in Series/Parallel to make one 50!) Waiting for the first one to break in now, I found they need a day or so to sound right...