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Another AR 3a crossover question


Dchristie

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I recently received in a trade, a bunch of AR3a parts including crossover components and drivers ( except the woofer which was sold by the original owner and the 16 ohm potentiometers). I have a pair of spare KLH model 17 woofers so I am going to play around with using the 3a mid and tweeter with the KLH woofer. I am just in the experimental phase so just looking at options - I have not tried any combinations yet.

I have a Marchand electronic crossover that I am going to actively biamp the woofer to the mid/treble drivers but use the stock 3a crossovers for frequency shaping for the mid and high units respectively. So, I will not need a low pass ( high cut) for the woofer or high pass ( low cut) for the mid as the Marchand will actively roll off the highs to the bass driver and also the lows to the midrange driver. I do want to use the standard passive 3a low pass and high pass crossovers for the midrange and tweeters, respectively. I would also like to play with the potentiometers in and out of the mid and high frequencies circuits since the marchand will allow flexibilty in level matching the bass with the mid/highs but I will still have to subjectively adjust levels between the mid and high frequency drivers to balance out the levels for the whole system. The reason for taking the potentiometers out of the mid and upper frequency crossovers is I also have 3 amps with level controls so another option would be to triamp each driver with the electronic crossover between the bass and mid ( levels can be adjusted for each of these with the electronic crossover) and the tweeter could be adjusted by the tweeter amp with the amp's level controls ( to balance the sound with the mid and low drivers).

So my questions for Roy C. ( or anyone else) are as follows :

When looking at the AR 3a crossover, it looks like there is a a 0.044 mH inductor in series with the 16 ohm potentiometer providing the high cut on the mid and a 6 uF cap on the tweeter also in series with the potentiometer for the low cut for the tweeter.

Is this correct ?

I assume the 0.88 mH inductor and 50 uF cap are providing the low cut for the mid in this circuit ?

If the above is correct, would the same value ( 0.04 mH and 6.0 uF) d components be acceptable for rolling of the highs to the mid and the lows to the tweeters IF the 16 ohm potentiometers were removed from the circuits or are the potentiometers in circuit critical to the high cut and low cut values of the mid and tweeter respectively and would need to be recalculated without the potentiometers in the crosssovers ?

As I indicated, I am just experimenting and I am sure my ignorance of cirduit designs is showing but I would appreciate any advice and clarification anyone can provide.

Thanks !

Dean

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So my questions for Roy C. ( or anyone else) are as follows :

When looking at the AR 3a crossover, it looks like there is a a 0.044 mH inductor in series with the 16 ohm potentiometer providing the high cut on the mid and a 6 uF cap on the tweeter also in series with the potentiometer for the low cut for the tweeter.

Is this correct ?

I assume the 0.88 mH inductor and 50 uF cap are providing the low cut for the mid in this circuit ?

If the above is correct, would the same value ( 0.04 mH and 6.0 uF) d components be acceptable for rolling of the highs to the mid and the lows to the tweeters IF the 16 ohm potentiometers were removed from the circuits or are the potentiometers in circuit critical to the high cut and low cut values of the mid and tweeter respectively and would need to be recalculated without the potentiometers in the crosssovers ?

As I indicated, I am just experimenting and I am sure my ignorance of cirduit designs is showing but I would appreciate any advice and clarification anyone can provide.

Thanks !

Dean

Dean,

You've pretty much got it right, but just to clarify... .the .88 mh inductor is in parallel with the mid, and provides a steeper slope. All of these components are necessary if you want to keep the tweeter/mid relationship the same as original.

As for the pots, if you remove them completely, you should place a 15 ohm resistor in parallel with the tweeter and another with the mid. This will be as if the pots are still in the circuit at the fully "increased" position. Alternatively, leave the pots in, and place a jumper wire between "1" and "B" of each pot terminal. Completely removing the parallel resistance will change things, such as the crossover point.

You should move this discussion to the mods and tweaks section of the forum.

Roy

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