Past couple of months i went a little slow on my diy endeavours and was looking at boosting the low end of my speakers which were a bit lacking there due to OB loading. Using a subwoofer on a long term was not an option for me either due to space constraints in my room. I have noticed that bi-amping was required for me as the tube amplifiers were unable to drive the low efficiency woofers. The mids and highs were 103db and 108db efficient but the woofer were just a 93dB types.
I tried biamping using passive crossover at the woofer, but due to over damped Q of my speakers, unable to get any reasonable LF lift in my setup. Instinctilly i bought a pair of JBL car subwoofers chiefly because they were within my budget and no harm in trying them out. I did not want to go for a high Q woofer because i thought that would have some sustain of the bass and cause them to ring. The JBLs had a Q of 0.55 which is a bit overdamped. But i have tried woofers with a Q of 1.2 and they defentitely ring at the bottom end. The JBL have a low Fs (28Hz) and high Mms (174gm) cone which means it would require a high wattage amplifier to drive them. My Denon AVR is around 130watts RMS at 4 ohms sufficient enough for my room.
What i later did is EQ my low end by appling an analogue GE from freq 20 Hz to 40Hz at +12dB and flated till 300Hz and then -12dB from 300Hz tp 20KHz. This is an active analogue filter for my low end for the woofer.
For the midrange and tweeter - the midrange response was extended till 100Hz (-6dB) and there was a overlap with the woofer which i wanted to avoid. I used an passive high-passs shelving circuit in the pre-amplifier to have the roll-off from 400Hz onward @ -6db/octave. Now the tube ampifier is fed signals from 200Hz (-6dB) till 20KHz without any active device (this is well explained in the Linkwitz lab website). The mid range and high frequency are again using a passive series crossover using just one inductor and 2 resistors (made out of manganin wire). Hence i termed this type of crossover as hybrid crossover which uses best of the 2 worlds as appropriate.
Measured response at listening position 2.5 meters away - the speakers are paralllel to the wall with no toe-in.
Thanks for looking.
I tried biamping using passive crossover at the woofer, but due to over damped Q of my speakers, unable to get any reasonable LF lift in my setup. Instinctilly i bought a pair of JBL car subwoofers chiefly because they were within my budget and no harm in trying them out. I did not want to go for a high Q woofer because i thought that would have some sustain of the bass and cause them to ring. The JBLs had a Q of 0.55 which is a bit overdamped. But i have tried woofers with a Q of 1.2 and they defentitely ring at the bottom end. The JBL have a low Fs (28Hz) and high Mms (174gm) cone which means it would require a high wattage amplifier to drive them. My Denon AVR is around 130watts RMS at 4 ohms sufficient enough for my room.
What i later did is EQ my low end by appling an analogue GE from freq 20 Hz to 40Hz at +12dB and flated till 300Hz and then -12dB from 300Hz tp 20KHz. This is an active analogue filter for my low end for the woofer.
For the midrange and tweeter - the midrange response was extended till 100Hz (-6dB) and there was a overlap with the woofer which i wanted to avoid. I used an passive high-passs shelving circuit in the pre-amplifier to have the roll-off from 400Hz onward @ -6db/octave. Now the tube ampifier is fed signals from 200Hz (-6dB) till 20KHz without any active device (this is well explained in the Linkwitz lab website). The mid range and high frequency are again using a passive series crossover using just one inductor and 2 resistors (made out of manganin wire). Hence i termed this type of crossover as hybrid crossover which uses best of the 2 worlds as appropriate.
Measured response at listening position 2.5 meters away - the speakers are paralllel to the wall with no toe-in.
Thanks for looking.
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