4500Hz Network Builder
STEP 1

Factory Reference

Choose the verified speaker and factory network first. The factory squawker/tweeter HF arrival is the reference up to the model's woofer crossover region; incomplete references stay disabled until their data is imported.
4500X CONVERSION
Use a replacement tweeter capable of crossing at 4500 Hz, pad it to match the midrange, and keep the squawker/tweeter HF arrival at the woofer crossover region as close to factory as possible.
Factory elementsWoofer: K-22 familyMidrange: K-55-V / K-55 familyTweeter: K-77 / K-77-MSystem: 8 Ω nominalLower entry: 700 HzBasis: L1 2.5 mH / C2 2 µFVerified electrical reference: Heresy I Type E
Proposed changeNew tweeter: Celestion CDX1-1412Load: 8 ΩTarget: 4500 Hz handoffHF parts sized from the selected span loadWiring sheet generated from the selected build
STEP 2

Proposed 4500X Setup

Select only parts with complete impedance and span data. The app keeps one shared autoformer input span and disables incomplete candidates.
BUILD OPTIONS
Choose whether span selection protects the squawker SPL target first or lets the HF arrival score choose first. C2 is still scaled to preserve the factory squawker high-pass.
4500X corrects the replacement tweeter as a measured driver, not as a nominal 8 ohm load. DE120/CDX1-style impedance behavior is why this is not a simple first-order 4500 Hz conversion.
SQ 0-5 to 0-2TW 0-5 to 0-2Common Tap 0Shunt Tap 5 - Tap 0
T2A only has 3 dB output steps. The app lands on the nearest available tap when the requested target falls between taps.
TARGETS & VOICING
Set the midrange/HF arrival first. This is the factory behavior the app keeps close up to 700 Hz.
Then trim the replacement tweeter relative to the midrange. The app picks the tweeter tap separately; C2 remains a squawker high-pass match to the factory network.
SQ / HF arrivalFactory -10 dBTarget -10 dBat factory target
TW / midrangeFactory relationship -1 dBTarget -9 dB totalat factory target
RECOMMENDED TAPS / C2
Recommended buildOpen the Wiring tab for the bench connection diagram.
T2ASQ 9.0 dBTW 9.0 dBC2 2 µFNo shunt
C2 / SPAN LOAD
Select the load condition for the shared autoformer span. C2 always feeds the autoformer; an R1 row uses the listed C2 and Lx together.
App pick no shunt63.5 Ω reflected96.0 Ω at AF input1.87 µF C2 start2 µF closest2 µF next upNo LxR1 not installed2.00 µF factory C2
ShuntLoadCalculatedClosestNext upLx
Span load optionsEach row is a complete load condition. No shunt uses C2 alone; an R1 row uses the listed C2 and Lx together.
Measured impedance checkK55 curve + CDX1-1412 on new 77 lens at the 700 Hz factory-match window. This verifies that the proposed C2 preserves the factory squawker high-pass behavior; acoustic SPL still depends on driver sensitivity and measurements.
96.0 Ω measured model load1.87 µF factory-equivalent C27% vs selected capmeasured check close
ONE AUTOFORMER INPUT SPAN
The midrange and tweeter share one physical autoformer input span. The app changes span only to improve attenuation match: squawker first, tweeter second. If the span changes, both drivers move to the new span and each gets the nearest available output tap there. T2A only has 3 dB output steps. The app lands on the nearest available tap when the requested target falls between taps.
MIDRANGE OUTPUT TAP
Target -10 dB on shared span 0-5.
AttenOutputRef ZChoice
TWEETER OUTPUT TAP / C2
Target -9 dB on shared span 0-5. C2 follows the effective impedance at the autoformer input, so output tap changes matter through the load they reflect back to that input.
AttenOutputNo shunt10Ω15ΩChoice
STEP 3

Stud Finder Results

Review how the proposed taps, C2, and shunt compare with the factory electrical behavior before treating the build as ready.
FACTORY COMPARISON
Heresy I Type E HF Arrival Match: Troublechecked up to 700 Hz
The proposed squawker/tweeter HF arrival is materially different from the Type E reference up to 700 Hz.
37.2 dB RMS mag55.5° RMS phase17 samples to 700 Hz
PRIMARY CHECK
HF arrival Trouble
RMS magnitude37.2 dB
Max magnitude62.2 dB
RMS phase55.5°
Max phase71.9°
SUPPORTING CHECK
C2 / Load OK
Factory C2 load89.7 Ω
Selected load96.0 Ω
Factory delta+7%
Nearest C22 µF
VOICING CHECK
TW on target
SQ target-10 dB
SQ actual-9.0 dB
TW target-9 dB
TW actual-9.0 dB
ShuntC2 checkC2 loadFrom factoryC2Flag
FACTORY HF ARRIVAL CHECK — 10-700 HZ
Read this asorange is the factory squawker reference; blue is the proposed squawker path. Closer overlap means the HF branch is arriving more like factory in the woofer crossover region.
Trouble37.2 dB RMS magnitude, 55.5° RMS phase
4500 Hz takeoverThe replacement tweeter is judged at the 4500 Hz handoff against the squawker target, not in this 10-700 Hz arrival graph.
MAGNITUDE / SLOPE, 10-700 HZ
10 Hz700 Hzhigher level
PHASE DELTA VS FACTORY, 10-700 HZ
10 Hz700 Hz0° factory reference+90°-90°
This check compares the stored Heresy I Type E squawker reference against the proposed squawker path for the selected taps, C2, shunt, Lx, and verified driver impedance curves. The replacement tweeter is handled by the 4500 Hz takeover target and is not used as the 10-700 Hz factory-arrival reference.
C2 LOAD TRACE: HERESY I TYPE E VS SELECTED 4500X
Factory Heresy I Type ESelected taps / C2 / No shunt
20
6Ω / 12Ω6.7 dB
25
7Ω / 13Ω5.3 dB
31.5
9Ω / 14Ω4.1 dB
40
11Ω / 16Ω3.1 dB
50
14Ω / 18Ω2.4 dB
63
17Ω / 21Ω1.8 dB
80
22Ω / 25Ω1.4 dB
100
26Ω / 30Ω1.1 dB
125
32Ω / 35Ω0.9 dB
160
39Ω / 42Ω0.7 dB
200
45Ω / 48Ω0.6 dB
250
51Ω / 55Ω0.6 dB
315
58Ω / 64Ω0.7 dB
400
114Ω / 117Ω0.2 dB
500
78Ω / 77Ω-0.2 dB
630
79Ω / 82Ω0.3 dB
700
90Ω / 96Ω0.6 dB
The build changes the HF components so the replacement tweeter can take over at 4500 Hz instead of the factory handoff around 6500 Hz. The factory-match target is the squawker/tweeter HF arrival into the woofer crossover region up to 700 Hz.
A weak HF arrival score is a warning to review C2, shunt, impedance data, or measurements. It is not a directive to ignore the squawker SPL target.
HERESY I / TYPE E
verified driver data1967-1985, with late transition variantsWoofer K-22 familyMid K-55-V / K-55 familyK-700Tweeter K-77 / K-77-MSystem 8 Ω nominalWoofer reference near XO 11 ΩVerified Heresy I Type E electrical referenceSQ target -10 dBTW target -9 dBLower XO 700 HzWoofer Z 11 Ω2.00 µF factory C2Factory tweeter cap 2 µFFactory autoformer T2AT2A 0-5K55 0-5 -> 0-2K77 0-5 -> 0-3TW C4a 4 µFTW L4 0.16 mHTW C4b 6.8 µFSQ L2 0.51 mHSQ L3 0.51 mHSQ C3 1.5 µFWoofer 4/8 ΩSquawker 14.5 ΩTweeter 8 Ω
The factory spec is an 8 ohm system with K-22/K-55/K-77 parts. The Type E Stud Finder model uses the in-cabinet K-22 reference curve, represented near the woofer crossover as about 11 ohms. Factory baseline is Heresy I Type E: C2 2uF before the autoformer, no woofer shunt cap C1, T2A 0-5 input, K55 path 0-5 -> 0-2, K77 path 0-5 -> 0-3. Proposed 4500X tweeter branch uses C4a 4uF / L4 0.16mH / C4b 6.8uF; proposed squawker shaping uses L2 0.510mH / L3 0.510mH / C3 1.5uF. C2 always feeds the autoformer and is chosen from the effective impedance seen at the autoformer input, not from the tweeter 4500Hz high-pass.
AMP & OUTPUT CHECK
These values do not choose the tap. They show expected voltage, power, and load once the taps are selected.
W
T2A — 0-5 SPAN, 3 DB STEPS
CONNECTIONTURNS RATIOATTEN (DB)Z MULTREFLECTED ZOUTPUT VOUTPUT WC2C2 + 10Ω R1C2 + 15Ω R1SPAN LDCR (Ω)SHUNT SPANNOTE
Tap 5 -> Tap 51.00000.0 dB1.000×8.0 Ω20.00 V50.00 W22.43 µF51.16 µF43.58 µF55.694 mH12.0800Tap 5 - Tap 0T2A 0-5 full input span
Tap 5 -> Tap 40.7079-3.0 dB1.995×16.0 Ω14.16 V25.06 W11.24 µF36.98 µF29.40 µF26.570 mH3.4470Tap 5 - Tap 0T2A 0-4 output span
Tap 5 -> Tap 30.5012-6.0 dB3.981×31.8 Ω10.02 V12.56 W5.63 µF29.88 µF22.30 µF14.620 mH2.4020Tap 5 - Tap 0T2A 0-3 output span
Tap 5 -> Tap 20.3548-9.0 dB7.943×63.5 Ω7.10 V6.29 W2.82 µF26.31 µF18.74 µF7.323 mH0.8895Tap 5 - Tap 0T2A 0-2 output span
Tap 5 -> Tap 10.2512-12.0 dB15.849×126.8 Ω5.02 V3.15 W1.41 µF24.53 µF16.95 µF3.520 mH0.3389Tap 5 - Tap 0T2A 0-1 output span
AMP VOLTAGE
20.0 V
50W into 8Ω
AMP POWER
50 W
8Ω load
TWEETER Z
8 Ω
selected HF load
C2 BASIS
700
Hz factory-match window