ReadMeXO.TXT

Note that all schematics on these pages are (c) Copyright,
1996-1998, Steve Bench. All rights reserved. You may use or
build these FOR YOUR OWN use freely. You may NOT build and/or sell
for commercial profit, any of these without a royalty agreement
in place with the author.

You may place these schematics on your web page if you credit the
author.

Note that high voltages are present in these circuits. The author
IS NOT RESPONSIBLE for ANY injuries, damages, etc. associated
with construction, or use of these circuits.


The Tube (valve) crossover shown here is a 3 pole lowpass and
highpass used for a 2 way crossover design. The circuit needs
+150VDC and 6.3V filament power for its operation. A suitable
power supply is shown on these pages as SUPPLY1.GIF.

The circuit is a modification of a unity gain non-inverting
Sallen-Key circuit that provides 18 dB per octave rolloff
characteristics. The center frequency shown on the schematic,
but may be modified to any frequency with suitable scaling.
Some representative value changes are shown in this document.

A 3 way crossover may be implemented by cascading two similar
circuits as:

in---------- xover hp----------------------------high freq amp
                   lp----xover hp----------------mid freq amp
                               lp----------------low freq amp


Value changes for other crossover frequencies:

        LF Side	LF Side	HF Side	HF Side	HF Side	LF Side	LF Side	LF Side	HF Side
Freq	R4	R5,6	R9	R10	R11,12	C2	C3	C4	C6,7,8

800	90.9k	100k	88.7k	18.2k	1.3M	2200pF	0.01u	270pF	2200pf

80	90.9k	100k	88.7k	18.2k	1.3M	0.022u	0.1u	2700pF	0.022u
85	84.5k	93.1k	82.5k	16.9k	1.2M	0.022u	0.1u	2700pF	0.022u
100	732k	806k	154k	32.4k	2.2M	2200pF	0.01u	270pF	0.01u
125	576k	634k	124k	25.5k	1.8M	2200pF	0.01u	270pF	0.01u
170	422k	464k	154k	33.2k	2.2M	2200pF	0.01u	270pF	5600pF
200	365k	403k	158k	33.2k	2.2M	2200pF	0.01u	270pF	4700pF
400	182k	200k	174k	36.5k	2.7M	2200pF	0.01u	270pF	2200pF
850	84.5k	93.1k	82.5k	16.9k	1.2M	2200pF	0.01u	270pF	2200pF
1000	73.2k	80.6k	154k	32.4k	2.2M	2200pF	0.01u	270pF	220pF
2200	73.2k	80.6k	154k	32.4k	2.2M	1000pF	4700pF	120pF	100pF
3300    73.2k   80.6k   82.5k   16.9k   1.2M    660pf   3000pf  82pF    270pF
4800	73.2k	80.6k	75.0k	16.2k	1.1M	470pF	2200pF	62pF	91pF