4425 Re-Diaphram

[johnlcnm]

Did download a program, "Fuzzmeasure". Ran a number of sweeps inside the house. Without amp EQ the pads were flattest with 2kHz set to zero and 10kHz set to min. Looks fairly flat and sounds good. I did not realize how much the 10kHz was up. Guess that is due to the new Radian diaphragms and maybe the difference in the 2416 and 2426 phase plug. Eric, I do remember you from Audiokarma. Sounds like you are overloaded with the 44 series. Maybe those 4430s would want to come to my place to live?--- Just kidding! The 4333Bs that followed me home came with one 2231H and one 2235H. I hope the efficiency at one kHz is the same. If not I may be on the hunt for another 2235H. Both had been re-foamed by the previous owner. He never got a chance to rebuild the rest of the speakers though. The cabinets had big holes gouged in the back for hanging I guess. The rats had also made a home in them at some time in their past. I removed the finish with a paint scraper and heat gun, filled and sanded the holes and gouges. The grills were in pieces. I rebuilt those. They need grille cloth and black paint. I sent the cabinets off to get walnut veneer. The 2405s were toasted so I replaced the series caps in both crossovers, even though they both read open. The caps look like they had been hot. A little on the brown side of the color spectra.

Man you are in the holy grail of JBL land!

John

[Zonker92]

Wow; you've had your work cut out for you! My 4435s were also a major project, with new veneer, refoaming, CCed crossovers, new grill cloths, new diaphragms, etc. Not that I'm complaining.

I sold the 4430s to a very happy man in SF; that was also for the best, as I'd run out of systems that could use them. I'll miss them, though.

[Rudy Kleimann]

Zonker,

The JBL's are in a completely different league. If I were mixing, I know what I would be using.

John

IIRC, Christopher Cross used a pair of 4425's in his studio, may still have them to this day. His first album, released in 1980, had superb sound quality. Still sounds good today IMHO

BTW- do you have a picture of your old driver phase plugs? You said they looked different. If they had 9 round holes in the phase plug instead of the annular slits, yours are probably early 4425's. I think those drivers were actually 2415H's. Diaphragm was not changed- only the part number changed, a la 2446,2447,2450,2451,etc.

Have you compared the crossover network components in your cabinets against the JBL Service exploded diagram? If yours had 2415H (round hole phase plug passages) The HF EQ filter section may be different in your 4425's than what was provided in the later models with 2416H drivers.

[Zonker92]

Thanks, Rudy. I have mine all buttoned up now and in service in my master bedroom system; no photos of the crossovers or phase plugs; sorry. They do sound very good to me, though.

The stands are a work in progress.

[johnlcnm]

IIRC, Christopher Cross used a pair of 4425's in his studio, may still have them to this day. His first album, released in 1980, had superb sound quality. Still sounds good today IMHO

BTW- do you have a picture of your old driver phase plugs? You said they looked different. If they had 9 round holes in the phase plug instead of the annular slits, yours are probably early 4425's. I think those drivers were actually 2415H's. Diaphragm was not changed- only the part number changed, a la 2446,2447,2450,2451,etc.

Have you compared the crossover network components in your cabinets against the JBL Service exploded diagram? If yours had 2415H (round hole phase plug passages) The HF EQ filter section may be different in your 4425's than what was provided in the later models with 2416H drivers.

Rudy,

I looked at the drivers. They are still in cold storage, i.e. the closet. They are the nine hole type. Date on the diaphragm is Sept 29, 1988. I don't think these speakers have ever been apart, at least before they came to me. No doubt the response with the 2426H and Radian diaphragm is a lot hotter on the top end. I do have the 12kH set to min. I also have a high frequency shelf of a couple of dB set up in the amp. Tried to photograph from the screen side but could not get a good photo. I will pull a diaphragm and get one from the back.

Regards,

John

[johnlcnm]

Thanks, Rudy. I have mine all buttoned up now and in service in my master bedroom system; no photos of the crossovers or phase plugs; sorry. They do sound very good to me, though.

The stands are a work in progress.

Zonker,

Looking good. So what position did your L-Pads wind up in? Did you notice an increase in the high frequencies with the Radian diaphragms? What do you think of the sound in comparison to your 4435s?

Regards,

John

[johnlcnm]

IIRC, Christopher Cross used a pair of 4425's in his studio, may still have them to this day. His first album, released in 1980, had superb sound quality. Still sounds good today IMHO

BTW- do you have a picture of your old driver phase plugs? You said they looked different. If they had 9 round holes in the phase plug instead of the annular slits, yours are probably early 4425's. I think those drivers were actually 2415H's. Diaphragm was not changed- only the part number changed, a la 2446,2447,2450,2451,etc.

Have you compared the crossover network components in your cabinets against the JBL Service exploded diagram? If yours had 2415H (round hole phase plug passages) The HF EQ filter section may be different in your 4425's than what was provided in the later models with 2416H drivers.

Rudy,

The photo, these are on an old 4430 horn, so disregard that. I got the horn with one of the 2426Hs that I bought for a replacement in the 4425s.

Regards,

John

[johnlcnm]

IIRC, Christopher Cross used a pair of 4425's in his studio, may still have them to this day. His first album, released in 1980, had superb sound quality. Still sounds good today IMHO

BTW- do you have a picture of your old driver phase plugs? You said they looked different. If they had 9 round holes in the phase plug instead of the annular slits, yours are probably early 4425's. I think those drivers were actually 2415H's. Diaphragm was not changed- only the part number changed, a la 2446,2447,2450,2451,etc.

Have you compared the crossover network components in your cabinets against the JBL Service exploded diagram? If yours had 2415H (round hole phase plug passages) The HF EQ filter section may be different in your 4425's than what was provided in the later models with 2416H drivers.

Rudy,
I did go back to some of your old discussion of the two HF drivers in the 4425s. I do appear to have early versions of the speakers. They have the five way binding posts. Diaphragms must have been replaced as the date on them was 1988. Need to find if the crossover was modified for the newer 2416 drivers.

Regards,

John