TubularMosfet
05-10-2007, 01:18 PM
I lucked into a pair of JBL 4673 systems. They were not treated well by the former owners, but I paid less for the two systems than I can get for one of the 2445J drivers on ebay.
Setting them up in my 128-year-old oak cabin office, I can clearly hear their shortcomings.
The 2225H on the left channel - the voice coil is rubbing at modest volume levels. Whatever the cause, there are only two cures (recone or replace).
The 2445J on the right channel exhibits distortion at low-midrange freqs (500-900hz), and moderate volume. This is probably a symptom of the same problem the left channel's LF driver has; 'excess rubbiness' of the coil.
Moving the left 2445J to the right cabinet, I get very acceptable quality, both from a sand amp (Denon AVR5700) and a modified Dynaco 70 tube amp. (They sound slightly different, but neither is sonically superior to the other. Logic says MOSFET is better, aesthetics say the tube amp is .... wow...pretttty gloooow.)
So now, the dilemma: I have one system with all bad drivers, and one system with not-so-bad drivers. If I fix the bad drivers, they'll never match the old drivers that I kept. If I'm going to recone them all, why stick with the 40Hz rollover on the 2225H's? If I mod these for 2235H-iness, do I need to make changes to the 3315A crossovers - the JBL docs imply there's a 40hz hi-pass filter in there - or will plugging a port or three do the job? Is there a better alternative to the 2445J's and the 2380A horns that won't cost a leg?
What is the wisest course if my goal is to make these 4673s sound truly spectacular without spending enough to buy a pair of Everests?
Yes Zilch, I read much of what you've been doing. Thank you for the (useful) ton of info.
Setting them up in my 128-year-old oak cabin office, I can clearly hear their shortcomings.
The 2225H on the left channel - the voice coil is rubbing at modest volume levels. Whatever the cause, there are only two cures (recone or replace).
The 2445J on the right channel exhibits distortion at low-midrange freqs (500-900hz), and moderate volume. This is probably a symptom of the same problem the left channel's LF driver has; 'excess rubbiness' of the coil.
Moving the left 2445J to the right cabinet, I get very acceptable quality, both from a sand amp (Denon AVR5700) and a modified Dynaco 70 tube amp. (They sound slightly different, but neither is sonically superior to the other. Logic says MOSFET is better, aesthetics say the tube amp is .... wow...pretttty gloooow.)
So now, the dilemma: I have one system with all bad drivers, and one system with not-so-bad drivers. If I fix the bad drivers, they'll never match the old drivers that I kept. If I'm going to recone them all, why stick with the 40Hz rollover on the 2225H's? If I mod these for 2235H-iness, do I need to make changes to the 3315A crossovers - the JBL docs imply there's a 40hz hi-pass filter in there - or will plugging a port or three do the job? Is there a better alternative to the 2445J's and the 2380A horns that won't cost a leg?
What is the wisest course if my goal is to make these 4673s sound truly spectacular without spending enough to buy a pair of Everests?
Yes Zilch, I read much of what you've been doing. Thank you for the (useful) ton of info.