Alexander Posted March 20, 2020 Share Posted March 20, 2020 There has been some confusion on changing tap points on an xo to alter the attenuation. Some people say not to do this, that would require a complete re designing of the xo and others have shared no concerns and make tap point changes. Both groups of people are respected in their fields so which is right? Quote Link to comment Share on other sites More sharing options...
DizRotus Posted March 21, 2020 Share Posted March 21, 2020 I have tried several taps on my Crites 3636 autotransformers without changing anything else on my Super Heresys. I don’t recall which tap they’re on now but they are several dB down on the squawkers and they sound great. Quote Link to comment Share on other sites More sharing options...
Deang Posted March 21, 2020 Share Posted March 21, 2020 9 hours ago, Alexander said: There has been some confusion on changing tap points on an xo to alter the attenuation. Some people say not to do this, that would require a complete re designing of the xo and others have shared no concerns and make tap point changes. Both groups of people are respected in their fields so which is right? Well, you can't just change the setting unless you change the capacitor value or use a swamping resistor on the midrange. I wouldn't call that "a complete redesign" - just a small modification which is required to keep the crossover point the same. 2 Quote Link to comment Share on other sites More sharing options...
pzannucci Posted March 21, 2020 Share Posted March 21, 2020 The change to the autoformer tap changes the downstream impedance. If you are using a 6db electrical crossover, you end up doubling or halfing the capacitor value as you double or half the impedance. Refer to Crites 3636 autoformer specs for the impedance multiplier. https://critesspeakers.com/3636atz.pdf Of course measure to insure the impact on the driver is as in theory and if you don't know the specs of the autoformer but apply what Dean has pointed out. You'll likely not hear any significant difference. Quote Link to comment Share on other sites More sharing options...
Wirrunna Posted March 21, 2020 Share Posted March 21, 2020 A paper explaining the theory behind the use of an autotransformer and swamping resistor to allow adjustable attenuation of drivers in a crossover network. (by Al Klappenberger) is here - http://www.alkeng.com/dload_xo.html Quote Link to comment Share on other sites More sharing options...
mopardave Posted March 21, 2020 Share Posted March 21, 2020 12 hours ago, DizRotus said: I have tried several taps on my Crites 3636 autotransformers without changing anything else on my Super Heresys. I don’t recall which tap they’re on now but they are several dB down on the squawkers and they sound great. Same here. I'm one tap down in number from what Claude originally suggested. Sounds awesome 1 Quote Link to comment Share on other sites More sharing options...
Deang Posted March 21, 2020 Share Posted March 21, 2020 Without a change in capacitor value or a swamping resistor across the driver, you’ve changed the crossover point. Quote Link to comment Share on other sites More sharing options...
Schu Posted March 21, 2020 Share Posted March 21, 2020 I am quoting here... this is what happens to the crossover profile when you drop that tap to try and attenuate. It creates a 'bark' in the profile... 1 Quote Link to comment Share on other sites More sharing options...
mopardave Posted March 21, 2020 Share Posted March 21, 2020 6 hours ago, mopardave said: Same here. I'm one tap down in number from what Claude originally suggested. Sounds awesome Before I changed that tap, the mid driver a 55m sounded very distorted when I put my ear up to it. After changing tap the mid sounded very clean and clear. When I stood back listening the speaker sounded much better. Quote Link to comment Share on other sites More sharing options...
Alexander Posted March 22, 2020 Author Share Posted March 22, 2020 On 3/21/2020 at 6:58 AM, Wirrunna said: A paper explaining the theory behind the use of an autotransformer and swamping resistor to allow adjustable attenuation of drivers in a crossover network. (by Al Klappenberger) is here - http://www.alkeng.com/dload_xo.html Thank You for the link Quote Link to comment Share on other sites More sharing options...
jason str Posted March 23, 2020 Share Posted March 23, 2020 Some of us find the sweet place is right in between the two using the 3636 autotransformer. Quote Link to comment Share on other sites More sharing options...
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