Heresy woofer phase

[richbarrett]

I was tolt that in the 70's some time a mod was made to reverse the polarity on the woofer which improved the sound.Anyone have any info on thi?

[Groomlakearea51]

Never heard of that mod.... Check with Bob Crites (BEC), or DeanG and see if the've fooled around with polarity on the H's woofers.

[Invidiosulus]

I think they changed the phase on the midrange at some point not the woofer.

-Josh

[WMcD]

You need a copy of The Dope From Hope which I posted here http://forums.klipsch.com/forums/p/51635/492632.aspx#492632

Vol. 15 No. 1 describes the mod.

My read is that it was the mid and tweeter which was reversed in polarity rather than the woofer.

The DfH is interesting to read and you'll see some other articles on the H.

Wm McD

[Groomlakearea51]

WmMcD is correct; it was that mod in 1975 which resulted in the Type-E crossover. The earlier type was the C.

[JohnA]

Type C used with E-V SP-12, K-55-V, K-77

[JohnA]

Type D used with K-22, K-55-V and K-77

[JohnA]

Type E. Used with K-22, K-55-V and K-77/K-77-M.

All 3 designs are esentially the same except for the phase reversal in the Type E and the difference in attenuation in the Type C (plus the capacitor size difference caused by that).

You could reverse the woofer phase on a Type C or D and accomplish the same thing for a little less effort.

[djk]

"You could reverse the woofer phase on a Type C or D and accomplish the same thing for a little less effort. "

The more 2nd harmonic distortion a sysyem has, the easier it is to hear absolute polarity.

I can hear it on a K22E.

[Malcolm]

,,,it was that mod in 1975 which resulted in the Type-E crossover. The earlier type was the C.

Actually, the mod was to the Type D network. The Type D was just a capacitor change and autotransformer change from the Type C to account for the change from a 16 ohm woofer to an 8 ohm woofer. My guess is they assumed that the change in impedance at the crossover point wouldn't adversely affect the sound, then found out later that it sounder better with the phased reversed per the Type E.

[JohnA]

,,,it was that mod in 1975 which resulted in the Type-E crossover. The earlier type was the C.

Actually, the mod was to the Type D network. The Type D was just a capacitor change and autotransformer change from the Type C to account for the change from a 16 ohm woofer to an 8 ohm woofer. My guess is they assumed that the change in impedance at the crossover point wouldn't adversely affect the sound, then found out later that it sounder better with the phased reversed per the Type E.

My H700 has a Type C network and the woofer is an SP-12B that is an 8
Ohm woofer DCR ~ 6.5). The Heresies I have have Type E networks and K-22 Woofers
that have a DCR of ~7.8 ohms. The changes made to the 3 networks had no effect on the woofer and only changed the output of the squawker and tweeter. They were not made because of a change in the woofer's impedance (the woofer inductor is 2.5 mH in all 3), but COULD have been made because the K-22 had more output than the SP-12B. The difference is very small IF the K-22 is more sensitive.

I have changed all of my Heresies to match the H700/Type C configuration. They test flatter that way.