Hi All,
I have had a pair of HK Premium Pro 12s for a while, I have been pleased with them given the cost. I recently came across an article where he measured the impedance curves of the individual drivers and calculated the required impedance correction circuitry. I followed the guide and was impressed with the difference. However I have noticed that when turned up the modified version sounds slightly muddled when compared to what I remember them previously sounding like.
HK Audio Pro-12
I can post photos of my modifications however I am using effectively the same components. I was thinking could the iron core inductor possibly be the reason for this?
I have had a pair of HK Premium Pro 12s for a while, I have been pleased with them given the cost. I recently came across an article where he measured the impedance curves of the individual drivers and calculated the required impedance correction circuitry. I followed the guide and was impressed with the difference. However I have noticed that when turned up the modified version sounds slightly muddled when compared to what I remember them previously sounding like.
HK Audio Pro-12
I can post photos of my modifications however I am using effectively the same components. I was thinking could the iron core inductor possibly be the reason for this?
A saturated inductor could be the problem for sure, does the speaker have a light bulb to protect the CD? Those can add some color too when lit up bright under heavy power.
How much power are you hitting these with anyway?
How much power are you hitting these with anyway?
Yes the crossover has a bulb inline. I am no where near their rated power. The signal led on the amp is lit however the -10db led isn't even flashing. The mixer is registering -20db with the gain on the amp set to -10db. I have a QSC PLX1804 so that would mean the amp isn't even delivering 50 watts to the speakers. I have attached a photo of the circuit installed.
Thanks
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Thanks
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I wouldnìt trust this page, the guy seems to have only Limp and no SPL with mike.
The HK site says crossover is at 2.2kHz.
The modification will lead to a dip in response from 1 to 3khz
It would be maybe better to compensate only the first impedance peak of the tweeter
The HK site says crossover is at 2.2kHz.
The modification will lead to a dip in response from 1 to 3khz
It would be maybe better to compensate only the first impedance peak of the tweeter
Ok thanks. The woofer compensation made the biggest difference. So I might just take the circuit out for the CD. Looking at their other speakers in the range, the 8 inch version for example, it looks like they included impedance correction on that model as there is an extra inductor on the xover, did they not include it on the 12 for a reason?
Is anyone able to help me with this please? My knowledge on speaker designing and modifications is very limited 😀
With speakers if it sounds good it is good, so your instincts are correct. I'd remove the circuit on the CD if it sounds better to you without it, that isn't something normally seen there anyway.
I don't get it. The manufacturer already has taken the impedance peaks of the drivers into account, when designing the crossover. If you add 'impedance correction' on top, the original crossover will be off.
Could the capacitor and resistor in parallel with the LF alter the crossover frequencies? The modified speaker with just that modification sounded better than the stock speakers but I am worried it could have lowered the crossover frequency?
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Well yes.. but that is what this modification does.
Without a correction for the rising impedance of the large woofer coil the actual crossover frequency of the working speaker is not what the theory suggests because textbook crossover filters require a flat speaker impedance. So yes your circuit addition will change the crossover but it's just bringing it back to where it should be.