Capacitor stacking and bypassing questions

[mark1101]

I have been experimenting with this in my AK-3 networks and would like some feedback.

I used a 12uf and a 1uf combination to make 13 (in the midrange filter). Is this a downgrade in performace from just a single 13uf cap? Could there be some smear do to different time constants of the 2 caps or is that a wives tale for these values? Can you measure smear or see it on a scope? If I had used two 6.5uf caps instead would that make any difference?

Next question.

I used some .1uf caps of a higher quality to bypass some 2uf caps of a lower quality in the tweeter filter. Again, I am concerned with smearing. Comments? Also, comments on how well this works.

I have to say, that I can't fault the sound just yet. But it is too early to be commenting really. I just did this last night. I will say that I definitely notice the difference in sound in the tweeter section. Those little .1uf caps definitely took some of the harshness and analytical sound out of the top end (from just the 2 uf caps alone).

Any comments would be appreciated.

Thanks

[BEC]

The caps in parallel simply add.

The 0.1uF cap would have an impedance of 160 ohms at 10 Khz and 80 ohms at 20 Khz. Its effect would in my opinion be inaudible in any crossover circuit.

Bob Crites

[Al Klappenberger]

Mark,

My opiion is that "bypass" caps at audio frequency is a waste of money. The best deal is to parallel two caps of equal value. If you want 13 uFd, parallel up two 6.8 uF caps. That comes to 13.6 uFd which is less than 5% error in value. The internal resistance (ESR) if a 6.8 is less than that of an equal quality 13 uF cap and the combination divides that already lower value in half. You can use simple Ohms law on the capacitive reactance of each cap to figure the amout of current that flows through each cap in a combination of two values. If you do, you will see that the larger value carries most of the current. I'm with Bob on this one.

Al K.

[mark1101]

Thanks for the info guys. The opinions are all over the place on this subject on the internet. I only got my self into this situation because I was too cheap to buy the better caps in the first place. Now it costs more. Everyone tries to save money. In this field it usually backfires. Do it right the first time.

[Al Klappenberger]

Mark,

I have two guide lines I live by:

1 - Nothing good comes cheap unless it's used.

2 - It's not what you do that counts, it's how well you do it.

Al K.