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Pass Labs B4 crossover questions
Pass Labs B4 crossover questions
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Old 13th June 2018, 07:36 PM   #401
R-K Rønningstad is offline R-K Rønningstad  Norway
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Quote:
Originally Posted by Nelson Pass View Post
Indeed, you can probably get it within a dB without too much effort.
Ref to Post 370 again.
This is the situation at 1 kHz. The woofer is lagging the tweeter by some ~380 us. The crossover should [somehow] compensate for this situation.
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Old 14th June 2018, 01:24 AM   #402
woofertester is offline woofertester  United States
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Quote:
Originally Posted by R-K Rønningstad View Post
Ref to Post 370 again.
This is the situation at 1 kHz. The woofer is lagging the tweeter by some ~380 us. The crossover should [somehow] compensate for this situation.
The crossover is intended to make summed response at the crossover point flat.

The phase response of the woofer with respect to the tweeter is a different matter. That the woofer lags the tweeter is not surprising .
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Old 14th June 2018, 05:48 AM   #403
R-K Rønningstad is offline R-K Rønningstad  Norway
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Of course.
As mentioned earlier the sum gives a 4 dB notch at 1 kHz. NP encouraged us to find a set of values for the crossover shown in post 370 to flatten that. The numbers I mentioned is part of the facts one has to work with. Maybe I stated the obvious, but it was to get to a better second order filter.
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Old 14th June 2018, 04:10 PM   #404
mcluxun is offline mcluxun  United States
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Will this work with Quad ESLs and OB subwoofers?
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Old 14th June 2018, 06:16 PM   #405
Nelson Pass is offline Nelson Pass  United States
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Pass Labs B4 crossover questions
Quote:
Originally Posted by R-K Rønningstad View Post
As mentioned earlier the sum gives a 4 dB notch at 1 kHz. NP encouraged us to find a set of values for the crossover shown in post 370 to flatten that. The numbers I mentioned is part of the facts one has to work with.
Here's a cheap example, a 2 pole pair of filters which sum flat at 1 KHz
but paired with drivers that roll off at 500 Hz (tweeter) and 2 KHz
(woofer).

If we play with the values a bit, we improve it to about +/- .5 dB.

You can probably do better than that, this took me a minute.
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Old 14th June 2018, 07:09 PM   #406
R-K Rønningstad is offline R-K Rønningstad  Norway
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Quote:
Originally Posted by Nelson Pass View Post
Here's a cheap example, a 2 pole pair of filters which sum flat at 1 KHz
but paired with drivers that roll off at 500 Hz (tweeter) and 2 KHz
(woofer).

If we play with the values a bit, we improve it to about +/- .5 dB.

You can probably do better than that, this took me a minute.
You are smarter and faster than me, sir!
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Old 17th June 2018, 03:29 PM   #407
luxwinter is offline luxwinter
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Originally Posted by mcluxun View Post
Will this work with Quad ESLs and OB subwoofers?
I purchased the First Watt B5 for the sole purpose of integrating dipole subs with the ESL 57. It works amazingly well. It's also quite cost effective by my reckoning, because amplifiers that can are transparent enough to do justice to the Quads AND can control the panels at low frequencies tend to be... expensive. With a high pass filter in the mix, my little EL84 amps do a much better job with the Quads. You of course have a lot of parameters to experiment with in the crossover point. I like 80hz second order the best.

Right now, I'm using a full range driver instead of the Quads - they're great, but the Quads are greater and I'm going to repair them soon and put them back in service.
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Old 17th June 2018, 09:06 PM   #408
R-K Rønningstad is offline R-K Rønningstad  Norway
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This might be some kind of a "philosophical question".
A crossover intended to cross between a subwoofer (or two) and some full range speaker like a Quad, Martin/Logan or a Maggie, could as well be designed with some integrated circuit operational amplifier for the low pass part while the high pass part of it could use the Toshiba JFETs. As long as you have your crossover just up to a few hundred Hertz. If you cross at 1 - 2 - 3 - 4 kHz it is anotherthing.
Fun with JFETs, but they could be saved from crossing basses, dipole compensation and so on.
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Old 18th June 2018, 05:52 PM   #409
Nelson Pass is offline Nelson Pass  United States
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Pass Labs B4 crossover questions
No reason not to. This endeavor is about entertainment and doing
things yourself. Toward that end, the advantage of the discrete parts
is that they bring your efforts closer to the signal.
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Old 18th June 2018, 08:16 PM   #410
R-K Rønningstad is offline R-K Rønningstad  Norway
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Yes, I my thinking goes the bass is close enough with a good opamp while for the higher frequencies we feed our SIT-amps etc from the JFET "upper half" of our crossover. On the other hand, I have quite a few JFETs.....
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