Optimizing the Bass Response of an old reconstructed 1984 pair of speakers with new drivers & crossover

[alexpriftis85]

Hello everyone and i wish you a happy new year!

I have a pair of no name 1984 speakers that have 2 x 4ohm Tweeters & 2 x 4ohm 8 inch woofers and the cabinet internal size is around 62 litres.

These speakers where my father's and hold sentimental value to me so i thought i would fix/upgrade them by replacing the fried tweeters and the torn woofer cones.

So i kept the original box but i bought new drivers and a crossover and built a bass reflex port (they where sealed).

So what i did was :
- Replace the tweeters with new ones => Bullet type 4ohms each 3khz-20khz connected in series
- Replace the 2 x 8 inch woofers with:
--1 mid woofer 4ohm 60hz-5khz
--1 sub woofer 4ohm 32hz-150hz

• Added a bass reflex port with 7cm diameter and 60cm in length to tune it to 30hz according to the sub woofer's thiele small parameters and internal box size (used win ISD)
• Added insulation inside the box (there was none)
• Added a two-way crossover with a crossover point at 5khz @ 8 ohms 2nd order, 12db/octave ( the speaker had no crossover just a single capacitor previously)
• I broke the subs in for 4 hours in free air by playing a sweep of 25-hz-100hz in a low to moderate volume level to loosen the suspension

My concerns:

• Since the sub & mid woofer are in series to present an 8ohm nominal load the sub will be getting more frequencies than necessary.
• That could potentially cause distortion and the system is not as efficient as it should and lose performance.
• I'm also concerned about phase issues as the mid woofer and subwoofer have an overlap across 60hz-150hz (according to what the manufacturer states in each of the drivers specs).

While Listening to them:

• Even though the bass is deep and present i have to crank the eq to +6db to get a good enough bass response out of them especially in low volumes
• When using a single powered 8 inch subwoofer the performance of the powered sub is MUCH better than my speakers at all volume levels

My questions:

• Why is the single powered sub has such a drastic difference in bass performace against my 2 x 8 inch passive subs? In order to get the passive subs to perform the same i need a boost of at least 6db on the eq/tone control to get the same performance which is really good by the way so it is not neccesarly a speaker problem but an amp problem?
• If i made a custom 3 way crossover for each of the drivers in the speaker would that dramatically increase the overall performance or would it be a slight increase in performace?
• If i did make a custom 3 way crossover i would strain the amplifier as i would present a 4ohm load instead of an 8ohm load
• Should i remove the passive subs from the speaker boxes and use 2 identical midwoofers instead? And rely on the active sub for the bass only?

Note: My living room is huge; it's around 65 square meters and 4.5 meters tall. To get best result i used the powered sub in conjuction with the passive subs integrated in the towers. I have a digital eq on my phone which i set up to boost +6db with a center frequency of 60hz and a wide q while i lowered the volume the powered sub plays to 1/4 so that it complements the passive subs. That way i get rich deep bass at low and high volumes without too much stress. I never listen to particularly high volume levels but i do listen to bass heavy music such as hip hop and house music.

Speaker pics attached, Looking forward to your expertise and suggestions!