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Keilidhs, crossovers and phase
2013-07-08, 16:57
Post: #1
Keilidhs, crossovers and phase
I know about the importance of polarity and ensuring that your speakers are in phase but I stumbled across these statements in a LINN Keilidh document about going aktiv: -

"The crossover used in the KEILIDH is a 2nd order crossover (which means that the treble is out of phase to the bass unit)"

And again

"The bass unit is in phase with the input signal and the treble unit out of phase to the input signal and the bass unit, ABSOLUTE PHASE IS NOW CORRECT"

Can someone translate into PLAIN ENGLISH please!?

My Serial Numbers are 42517/42518, i.e. above 21000, so I'm assuming my crossover boards have been changed?
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2013-07-08, 17:04
Post: #2
RE: Keilidhs, crossovers and phase
Not my pic, and not a Keilidh crossover, but it shows what is ment.

[Image: screenshot_141.jpg]

image upload

Follow the + and - from the drive units back to the input and you will see that they are wired different to each other. The Tweeter is therefore out of phase with the Bass

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2013-07-09, 10:03
Post: #3
RE: Keilidhs, crossovers and phase
And with a Keilidh crossover in passive configuration:
[Image: ie13yt.jpg]


Note how there are two red wires (the + of two bass units) and one black wire (- of the treble unit) connected to the left plates and the opposite on the right. The phase inversion is even clearer in active configuration as the top black/- wire shifts to T+ Act (on the left/+ side) whereas the upper-bass red/+ wire shifts from bottom left to UB+Act (ie remains on the + side).

LP12/Lingo 1.2/Ittok LVII/ESC-Troika/Linto, Karik/Numerik > Kairn > 2 Klouts/LK140 > K600 > Tri-Aktiv Keilidh/Sizmik 12.45
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2013-07-09, 13:24
Post: #4
RE: Keilidhs, crossovers and phase
Ah, the famous Keilidh crossover picture from mouldyolddough - did anyone ever sort out Royalties?

It's a pity there isn't a LINN schematic as clear as Mr Onion's that explains what's going on here - or is there? It's a bit more complicated with bi-wire cable.

I now understand the technical stuff and what needs moved and/or cut, but I'm still unsettled by the concept of the Tweeter being out of phase with the Bass - it seems counter-intuitive to me?

Anyway soldering iron at the ready - all I need now are Stereo Treble and Bass aktiv cards for my AV5125.

Final question (hopefully) - once I'm aktiv and I've done the business with my crossovers do I need to use the connecting plates between the middle and bottom bass drivers. The KEILIDH manual states "BI-AMPING The exact method of wiring your system in this configuration depends on the pre-amplifier and amplifiers you are using. Please contact your retailer for full information." I have a Unidisk SC and an AV5125.
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2013-07-09, 13:47
Post: #5
RE: Keilidhs, crossovers and phase
An awful quick edit to show how it would be bi wired.

[Image: screenshot_20.png]

image hosting

THIS might help you understand why (or there again, it may just make you even more confused)

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2013-07-09, 16:05
Post: #6
RE: Keilidhs, crossovers and phase
(2013-07-09 13:24)Donald Wrote:  Ah, the famous Keilidh crossover picture from mouldyolddough - did anyone ever sort out Royalties?

It's a pity there isn't a LINN schematic as clear as Mr Onion's that explains what's going on here - or is there? It's a bit more complicated with bi-wire cable.

I now understand the technical stuff and what needs moved and/or cut, but I'm still unsettled by the concept of the Tweeter being out of phase with the Bass - it seems counter-intuitive to me?

Anyway soldering iron at the ready - all I need now are Stereo Treble and Bass aktiv cards for my AV5125.

Final question (hopefully) - once I'm aktiv and I've done the business with my crossovers do I need to use the connecting plates between the middle and bottom bass drivers. The KEILIDH manual states "BI-AMPING The exact method of wiring your system in this configuration depends on the pre-amplifier and amplifiers you are using. Please contact your retailer for full information." I have a Unidisk SC and an AV5125.

Phase-inversion: This is standard for second-order crossover, the point being that the relative-phase of the two crossed units varies with frequency and that precisely at the crossover frequency there is a pi phase difference.

Connecting plates: If you drive your active Keilidhs with two amplifiers (one for the treble and one for the two mid/bass units) then the plates should connect the posts of middle and bottom bass drivers. When Triamping, remove the plates as otherwise you will shortcircuit the bass amps with catastrophic results. Needless to say, when active you should have the proper Aktiv crossover cards installed in the power amps.

LP12/Lingo 1.2/Ittok LVII/ESC-Troika/Linto, Karik/Numerik > Kairn > 2 Klouts/LK140 > K600 > Tri-Aktiv Keilidh/Sizmik 12.45
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2013-07-10, 17:40
Post: #7
RE: Keilidhs, crossovers and phase
(2013-07-09 16:05)ami Wrote:  Phase-inversion: This is standard for second-order crossover, the point being that the relative-phase of the two crossed units varies with frequency and that precisely at the crossover frequency there is a pi phase difference.

In other words, the components in the crossover introduce an undesirable phase shift which needs to be compensated for by inverting the phase of ONE of the drive units.
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2013-07-14, 09:02
Post: #8
Keilidhs, crossovers and phase
Now I am confused! Does this mean my tweeters are running reverse polarity? I have a Kairn, so amp to speakers I have swapped + and -.

Does this say in an Aktiv setup that tweeters should be swapped again? Please clarify.

Primary: Karik -> Numerik -> Kairn -> LK100 x 3 -> Tri-Aktiv Keilidh's
Secondary: Karik -> Majik -> LK100 x 2 -> Aktiv Keilidh's
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2013-07-14, 09:27
Post: #9
RE: Keilidhs, crossovers and phase
The easiest thing to do is ignore the whole 'tweeter reverse polarity' thing.

Just connect the amp and speakers as per instructions and forget the technicalities.

ie Non Inverting Amp + to + and - to -

Inverting Amp + to - and - to +

Going Aktive will not change this AFAIK as it will be taken into account in the Aktive filters.

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2013-07-14, 09:51
Post: #10
RE: Keilidhs, crossovers and phase
It is the capactiors in between the input signal and the tweeters that invert the phase. They are needed to block low frequency signals getting to the tweeters. Think of capacitors as a valve. They are closed for DC (steady) current, slightly open for low frequency current and wide open for high frequency. Inductors (coils) do the opposite - fully open for DC, wide open for low frequency and closed for high frequency. The capacitors have the side effect of flipping the phase of the signal as it passes 'through' them.

CJ

Main: Michell Orbe/SME V/Lyra Delos/CA 640p Oppo105 Kisto Klimax320a Komponent106 Komponent104

Profession: Owner of Krescendo HiFi - Specialist in second hand Linn and Naim
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