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Suggestions for a passive line-level high-pass crossover?

Looking for suggestions on a passive line-level RCA high-pass crossover that I can insert between my preamp’s outputs and the amplifier that is driving the mids and highs of my bi-amped speakers. I don’t need anything fancy or overly complex, but I am looking for audiophile-grade circuitry that will have the least sonic signature.

 

Specifically, I need it to be a 100 Hz high-pass crossover point, with a slope at of at least 12 db per octave. Doesn’t need to have a level control, adjustable settings, etc. Simple, but high-performance parts and sound.

 

Any suggestions?

 

Thanks gang!

 


128x128mhwalker
bdp24's avatar
bdp24
9,788 posts
 

A passive high-pass filter is commonly accomplished via the insertion of a single capacitor on the input jacks of the main speaker’s power amp, the value of the capacitor determined by: 1- The desired x/o frequency; 2- The input impedance of the power amp. However, this method creates only a 1st order, 6dB/octave filter. For a 12dB/octave (2nd order) x/o, filtering is best accomplished via an active x/o.

A reasonably priced but also high-quality active x/o is the First Watt B4 (all discrete circuitry---no IC’s, no Opamps), which provides all the filters one should need: 1st, 2nd, 3rd, 4th order (6, 12, 18, 24 dB/octave) slopes from 20Hz to 3200Hz, in 25Hz increments. The B4 retails for $1500, but Reno Hi-Fi (a main retailer of First Watt products) sells it at a discounted price. It is about to be discontinued, so get one while you can!

yogiboy's avatar
yogiboy
5,665 posts
 
How about this?
http://www.hsuresearch.com/products/high-pass-filter.html
Or this?
https://www.parts-express.com/harrison-labs-fmod-inline-crossover-pair-100-hz-high-pass-rca--266-274
rodman99999
6,131 posts
 
The following manual(for the Dahlquist DQ-LP1) contains a formula for, and a chart of, the values(capacitors and if needed, resistors) that will give you your desired crossover point(BUT- 1st order), based on the input impedance of your mid/high amp. Keep in mind that greater than a 1st order(6dB) slope will cause greater than 90 degrees of phase shift, in your mid/high drivers. For instance, with a 2nd order(12 dB/oct) filter, you may find the best sound with either the mid/high or bass driver connected out of phase, unless they were already designed for a higher order slope. I had always used polypropylene film and Vishay metal film resistors(when required), to achieve the absolute minimum signal distortion/degradation. I have installed such filters inside amps, at the RCA terminals, to eliminate the need for additional connectors and cables. See, "technical" on page 4: (https://sites.google.com/site/mpbarney/home/dahlquist-dq-lp1)  Don't know if you can use any of that, but- what the hell.......  =8^)
sfall
346 posts
 
Do a vertical biamp instead. You won't need the xover.
bdp24's avatar
bdp24
9,788 posts
 

Bi-amping vertically (rather than horizontally) does not negate the need for a x/o to accomplish. Neither of the two amps in a bi-amped system knows whether it is being used vertically or horizontally (other than in the sense of how the amp and speaker interact with each other), and that consideration has nothing to do with the x/o itself.

Using one amp for both the low-pass and high-pass on the same speaker (vertical bi-amp) has it’s advantages, and using one amp instead for either the low-pass or high-pass on both speakers (horizontal) has it’s. Using a solid state amp for the low-pass (bass) signal on both speakers, and a tube amp for the high-pass (mids and highs) on both, works great with many speakers.

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