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Capacitor values question. I need HELP.

Yester_Year

Yester_Year

New Member
Hey all,
I am rebuilding a set of crossovers for some Cerwin Vega PD-9s to put into some Cerwin Vega D9s and I am having a hard time finding exact matching values . An example is the original caps were 40uf, 1.5uf, 7uf, 5uf, and 3.5uf. I can only find a 6.8uf, a 3.3uf, and a 5.1uf. In some cases I can find the exact value but I have to buy a minimum of a 1000 units or 250 units and I do not want or need them. I know changing the values will change the sound how much of a difference is this going to make?
Thanks for you input and suggestions/advice.

Y_Y
 
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Pretty easy to combine values in parallel. As an example, you could combine a 6.8 w/ a .22(poly) for 7.02uf. The 1.5 may be pricey, film and foil only.
 
Are you looking at the Dayton 5% Metalized Polypropylene capacitors offered at Parts Express? No problem with the 40uf and 1.5uf values. Like drumbumb states it is easy to make the 7uf with a 4uf and 3uf in parallel. The 3.5uf with a 3uf and .47uf. Just use the 5.1uf for the 5uf.
 
drumbum said:
Pretty easy to combine values in parallel. As an example, you could combine a 6.8 w/ a .22(poly) for 7.02uf. The 1.5 may be pricey, film and foil only.
Click to expand...

Thanks for that. I did think about that the issue I have with this approach is that the factory caps were 100VDC and due to the power I am putting to these CVs I am going up to 250VDC and there is barely enough room for a 1 to 1 cap exchange. I don't see how I could pack 50% more caps on this surface. I should have mentioned the VDC change before and the size constraint. Sorry about that.
 
Parts Express doesn't have minimum quantities for capacitors, and you can parallel different values to get the exact value you desire.
 
Apolek said:
Parts Express doesn't have minimum quantities for capacitors, and you can parallel different values to get the exact value you desire.
Click to expand...

Ok all I concede :bowdown:, it looks like I have no choice but to build a crossover board and remote mount it inside the cab and add some additional leads from the board to get to the tweeter and midrange controls on the front of the speaker. I was trying to avoid that but I guess I do not have a choice. Thanks for the answers, even though you did confirm I have to do this the hard way :).
 
Usually +/- 10% of the original value is OK with caps, especially since a lot of speakers have 10% or even 20% precision caps in them to begin with.

You can hot-glue caps to each other to piggyback them. As long as there is room on the board for one of the caps, you can stick the other one to it. Nylon zip ties work too. Rotate them so the next poor soul can see the values on the labels.

For the 40 uf you can use a nonpolar electrolytic, they are much smaller than films and work fine for those high value caps. PE also has them.
 
Hey all. It looks like I was trying too hard to be perfect. EchoWars told me the same thing some of you did, the values that are available are close enough to not really even notice. So I am going with the closest value for each and be done with it. This will also save me from creating a remote board and running additional wires to get to the controls/fuse/circuit breaker that are all part of the front panel..
Thanks for the help.
 
No problem, let us know how it turns out!

When I first started restoring old tube radios, the new caps you could find easily were often 630V rated but I was replacing old paper foil wax caps with 200, 250 and 400V ratings. I was all concerned about having the right voltage ratings even though 630V will work just fine for those other ratings and the size was still smaller in most cases. After awhile I realized it was not worth worrying about.

If you get the gear restoration bug, one of these days you'll come across some really super speakers and you'll want to fuss over them and it will be worth it. :)
 
Yester_Year said:
Hey all,
I am rebuilding a set of crossovers for some Cerwin Vega PD-9s to put into some Cerwin Vega D9s and I am having a hard time finding exact matching values . An example is the original caps were 40uf, 1.5uf, 7uf, 5uf, and 3.5uf. I can only find a 6.8uf, a 3.3uf, and a 5.1uf. In some cases I can find the exact value but I have to buy a minimum of a 1000 units or 250 units and I do not want or need them. I know changing the values will change the sound how much of a difference is this going to make?
Thanks for you input and suggestions/advice.

Y_Y
Click to expand...

Sonicap has what you need.
1.5 check
3.5 use 3.3
5 check
7 check
40 use two 20's

Do not parallel small and large values like 6.8 w/ a .22 as someone suggested as the small cap acts as a bypass cap.
 
No, it is most definitely not a good thing unless you like adding artifacts to your music, artifacts that are not present in musical performances.
 
Hey now I am not trying to start anything. No need for popcorn:D.

Most arguments I have heard against bypass caps claim they do nothing. Its the first I have heard that they color the sound and add artifacts.

Just curious where F1nut is coming from.
 
elitopus said:
Hey now I am not trying to start anything. No need for popcorn:D.

Most arguments I have heard against bypass caps claim they do nothing. Its the first I have heard that they color the sound and add artifacts.

Just curious where F1nut is coming from.
Click to expand...

The whole bypass thing is new to me. Seems like using small value poly caps in parallel with large value electrolytic caps is something folks do. I assume this is to save money and maybe valuable real estate on cramped crossover boards. How this effects sound quality? I have not a clue.
 
The original idea behind bypass caps was to use a very small value cap of better quality than the larger electrolytic in an effort to help the larger cap perform better and there is something to that. However, when using already superior film/foil caps there's no point in using a bypass cap and in fact doing so creates unnatural artifacts.
 
Ok all. In case you were interested in the outcome here it is. I used some Dayton film caps from PE and got the closest they had to the desired values (see first post). I plugged them in and WOW what a difference. Now keep in mind that I also changed the crossover from the standard D9 to a PD-9 (stands for Power Digital 9) configuration. I did a side-by-side with a factory D9 AND a factory PD-9 vs the recapped PD-9 and what a difference. I am sure some of the difference is old caps vs new BUT it also really opened up the mids and highs. So if you want to wake up your old D9s with out too much of a change that can easily be reversed I suggest you try this mod. It is still a CV configuration for the purest in you. There is enough room to make the change in part because you are going to remove the large inductor to match the factory PD-9 configuration.
 
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