15/05/2019
All this text and more are soon on my website www.lautsprecher-service.at
I wanted to hear the legend - JBL 4435 - 120Kg double 15" woofers, compression driver in the high tones. I made 2700km to get them and now here they are in my home ( near fully restored and tunned Pioneer HPM-150)
First impression, not very deep bas, very sharp but with week resolution (micro details) but extreame big potential.
Restoring the speakers
First of all i changed the input connectors to WBT - the original are bad and does not offer good contact - bad contact means less current !
It can be done with ease - the crossover is monted on 10 or 11 screws its easy to take it out - cables are long enough.
Next i bought simple Audioquest Type 2 cables to provide good cable connection to the speakers. I know its my vision but i soldet the cables direct to woofers (bypassing the terminals providet by JBL)
Next i read about the internal / external crossover switch its bad couse all the current flows over such tiny plates .
See photos:
I made some listenings. Sound is MUCH MUCH better- the sharpness is almost gone (they are bright speakers - lets say NEUTRAL but not sharp . I got now much better deeper Bass , midrange is must better, the most improvment are in high tones - its fasterm, with high resolution.
I got with this simple work 80% better sound.
I wait for the improvment with new biased crossover CC charged coupled.
Here are some schematics i prepared + original schematic:
In next Post i will write of good sides of biased crossover
Wanted to add an capacitors storage energy units - got capacity - when its not connected to the amplifier its empty, it need to be loadet in fraction of seconds but still its must be loadet to have its value. When i use charged crossover its preload from the batery so the response is faster.
Lets take 2 MKP caps with 10 uF from two different supplyers.
Capacity is the same, both are polipropylene film caps - both should sound same - but they does not - why? for incense the difference can lay time of reaction of the cap.
I bought Miflex http://audiomiflex.pl/ caps
The price was a bargain, all of them got 600V but most important is its made in Poland in Europa not in China .For now testing the caps and new crossover + i did not connect 2 9V battery's yet.
All build together, extraordinary sound, dont know the difference between biased and not biased crossover yet. But what i find extraordinary are for incens pronunciation of each words in a liryc - there is even more going on in the record than on my old reference speakers WAtt Puppy from Wilson Audio!
