Just finished a restoration on some AR2ax's. Did the whole job, new pots, caps, even took the cabs down to bare wood before oil and Min-wax refinish. The cabinets stuffing had turned to dust so I replaced it with the dacron fiber-fil from the local craft store. The stuff came in 620 gram bag ( I used one bag in each cab) and is a bit denser than the yellow construction insulation that came out. When all put together it seems the bass is a little lacking, I am wondering if the fiber-fil is too dense, maybe a I used too much or is it just that the 2ax can keep up with the 3a's the are sitting next to? Wondered if anybody has had similiar issue.
Construction insulation vs fiber-fil?
- Thread starter Equine
- Start date
Register to hide this ad
Teradacto58
Super Member
I loved the sound of my old Advent W2's....stuffed full of foam sheets! Should never had sold of the speakers! I am going to restore my AR 2 &3a's in a couple years...good to know what to stuff them with!!
spkrdtr
spkrfixer
The 2ax's will never 'keep up' with the 3a's. They are quite different speakers. The 3a has both a larger cabinet and larger woofer.
The inherent densities of PET fiberfil and original fiberglass are quite different and equal weights of each will stuff quite differently into a given box volume.
The AR guru's over as CSP say the AR2ax with cloth surround should have 28 oz. FG. Later versions with foam surround woofers should have 18 ozs. They have also concluded after both theoretical and emperical studies that FG stuffing has the edge over polyester fiberfil. Edge meaning slightly lower bass.
The inherent densities of PET fiberfil and original fiberglass are quite different and equal weights of each will stuff quite differently into a given box volume.
The AR guru's over as CSP say the AR2ax with cloth surround should have 28 oz. FG. Later versions with foam surround woofers should have 18 ozs. They have also concluded after both theoretical and emperical studies that FG stuffing has the edge over polyester fiberfil. Edge meaning slightly lower bass.
I ended up playing around with the amt of fiber-fil last night. It was sort of a trial and error process of weighing the material on a triple beam (left over from my days of reckless youth), filling the cab then listening. Must of tried 10 different weights but I had a 12 pack of microbrew samples so it was a good project. Subjectivly at around 400 grams the bass was voiced the best relative to the mids and highs. There was a real sweet spot at that point, with around 300 gms bass got really boomy, almost like a subwoofer and above about 450 the bass got weak and by 500 gms almost dissappeared.
spkrdtr
spkrfixer
Congratulations! You did exactly what most don't do when stuffing their speakers. Your last sentence basically described what speaker gurus call underdamped (boomy bass=hi Q) and over damped (too little bass=low Q). At 400 gms, you stuffed at a rate of about 0.6 lbs/cu. ft. in your 2ax's. 400 gms = 14 oz., a bit less weight than the 18 recommeded for FG. It makes sense though with the density of PET being considerably less then FG. Therefore less wgt. of pet will fill a fixed volume with a comparable amount of fiber and it's the fiber that does the work in making the box seem larger than it really is.
Yes, optimizing fiber stuffing takes patience, a power screwdriver (prevents tennis elbow), and most importantly, a suitable libation to aid you thru the process!
Gang-Twanger
Resident Wharfedaliophool
Good stuff to know. Thanks for that info.
The OP did a great job with the trial and error. A lot of people don't have that much patience. I'm glad that my speakers (from around '73 or '74) still have the original stuffing, which hasn't deteriorated at all. Stuffed at the factory.
The OP did a great job with the trial and error. A lot of people don't have that much patience. I'm glad that my speakers (from around '73 or '74) still have the original stuffing, which hasn't deteriorated at all. Stuffed at the factory.
jimfet
Lunatic Member
Strange. I just did this today with my 2 subs. Tight'nd things up a bit. The cabs are 1cb/ft. and I split a 1lb bag of fiber-fil from PE between them. Per intructions. I put clear caulk behind the woofer edges and replaced the screws with larger ones. I'm done for awhile.
Last edited:
Yes, equine does ring a bell now.