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Just built a Type 'A' Crossover with Oil Caps..............


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I just finished building a Type 'A' crossover. This type 'A' had all oil caps.

I got some Motor Caps that were brand new(I was told not to use these motor caps and when I asked why - I never got a more scientific answer than "they were not made for audio"). Anyway I do lots of stuff I'm not supposed to do. I hooked a 10uf and 3uf in parallel and used a 2uf for the tweeter cap.

So I sat down and listened to my Belles, with one crossover on one and the other had Solen Caps for both the 13uf and 2uf. I moved the balance control back and forth from the Oil Cap Type 'A' to the Solen Type 'A'.

Guess what? I can't say that I heard a difference at all. I was expecting something like an Amp change with all of the heated debates on caps on this forum. I was a little surprised that the Motor Caps worked at all. ( I guess the Belles didn't know the caps were made for starting motors).

They do look cool on the crossover board, though16.gif

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Tony,

Yes I set the Pre-amp to Mono. Actually tried it both ways. I have only built a prototype. I won't be finished with the final product for a couple weeks.

Final Product will be on Zebrawood wiped with tung oil with Cardas Binding posts. (I know I have too much time on my hands. I will post a picture when I'm finished16.gif

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I think the problem is that even the same speaker will sound different when it is moved to a different place in a room. How can you comepare two different speakers with just a slight difference between them when they are not in exactly the same place at the same time? The answer is that you can't! The difference will only be a few dB and will be overwhelmed by the room.

Al K.

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AL,

Yes, thought of this and I set up a test to switch Crossovers on speakers, as the crossovers are external. Can do it real fast with banana plugs. Still I can't say I hear a difference. It may take a Golden eared Audiophile to hear it.

Nova,

Yup, just bought these and they clearly say 'No PCBs'

Dean,

I never said better, I said different. Solens are used by

some Manufacturers that I highly regard.

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OK DeanG,

"I think most would agree not to use a Solen in a critical part of the signal path."

Tell me what is the critical part of the signal path in my Type 'A' crossover? And please recommend a Capacitor where I will hear a HUGE difference over the Solens and the Vintage Oils.

I'll build them! and we'll see.

BTW - What caps do your speakers have in them?

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Interesting.

Let the oils burn in for ten or twenty years, then check again. You need to push all the negative, anti-musical electrons out of the capacitors, filling them up with positive, musical electrons before the differences will truly be heard. Try to play only Jorma Kaukenen music for the next decade or two. Hot Tuna will work in a pinch.

I wonder if this says something about Solens, or something about caps in general? Bet they still look cool, and are cheaper than the Solens of the world. I guess a change in amps would of necessity be easier to hear than a change in capacitor format. Maybe it will take some long term listening to discern a difference (if any).

ps,

put my order in for the Transcedence Seven. Still haven't gotten the 'air mail' check from Hong Kong.

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I just did some computer simulation on the type "A" and type "AA". It turns out that the loss through the tweeter filter of both at 17 KHz is only about 0.1 dB lower with caps having a Q of 1000 compared to a Q of only 100 (worse than oil which are about 200-300). I am not surprised you could not hear that difference. It proves the old wisdom that's it's the inductors that count. The total Q in a filter is 1 /(1/QL + 1/Qc)). That makes the difference 23 versus 29 assuming an inductor Q of 30. Since there is no inductor in the tweeter filter of the "A" network you can't upgrade the inductors! You do not seem to gain much by putting high Q caps in there either! At least that is what the computer says (beep).

Al K.

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AL,

Thanks for the info! Someday I'm gonna understand what you said! I swear!

As far as inductors go. I have the Solen Hepa-Litz 14 gauge on the woofer - 2.5mh variety. Is this what you'd recommend?

Randy,

Congrats on the Pre-amp purchase! I'll let you know how the crossover sounds in May of 2023.

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----------------

On 5/28/2003 10:24:06 PM Al Klappenberger wrote:

Cut-Throat,

The Litz wire woofer inductor is fine, but Litz wire doesn't do much for you at woofer frequency. It doesn't hurt though. Litz starts to pay off as frequecy increases. I generally recommend heavy soild wire for the woofer filter.

Al K

----------------

Al-If skin effect becomes an issue why not *default* to the theoretical ideal, copper foil? They effectively eliminate any losses associated with skin effect. They measure better than Litz and can be had in 16, 14 and 12AWG equivalents AND there cheap, for example a .22mH, 14AWG air core foil cost about $8 (Partsexpress).

I know builders that shy away from them because they don't know how to work with the foil. In reality it's pretty

straightfwd to make a joint that will last for years but it does take a littel extra work.

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John,

Skin effect isn't the effective factor. Skin effect dosn't start becoming a problem until you hit radio frequency. I am not sure why Litz wire makes for reduced loss at audio frequency, but it does! I think it may be due to eddy-currents flowing across the wire rather than down it's length. I have tested foil inductors. They are good but Litz wire inductors are significantly better and cost less. The foil inductors have lower distributed capacity due to the nearly equal phase from turn to turn, but that is of no importance to a crossover network.

Al K.

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I don't understand the physics of proximity effects. But I do not think skin effects are to be completely ignored. The effect is pronounced if the tweeter chokes are small diameter wire with high DCR. For large AWG (14+) the effect is negligible but Klipsch (and others) consider 18AWG and 20AWG as adequate.

Here's the plot I think of when considering skin effect of round copper conductors.

The Y-axis is the the DCR multiplication factor (or R/Rdc).

The X-axis is the frequency.

For frequencies between 10-20kHz the AC resistance is equal to between about 4-6x the DCR.

For an 18AWG solid core inductor with a value of .24mH the DCR is about .25Ohms.

At 10 kHz this becomes about 1Ohm and at 20 kHz this becomes about 1.5Ohms.

Not a big effect but not negligible either.

Perhaps proximity effects swamp this out. If so then I would have to A/B Litz against copper foil to judge.

skin%20effect.gif

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John,

I did make a direct comparison between about six different inductors, include a .2 mHy Solen litz and an Alpha Core spiral. It was posted here. This is the "search":

http://forums.klipsch.com/idealbb/view.asp?topicID=19827&forumID=81&catID=19&search=1&searchstring=&sessionID={A6733A35-C9A6-4351-AB70-DB4E173AE21F}

The results are:

Solen litz: Q at 6000Hz = 43.8, DCR = .128 Ohms

Altha Core: Q at 6000Hz = 29.4, DCR = .018 Ohms

The litz inductor wins hands-down. You tell me why!

Al K.

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