SR4726a vs SR4726X, filter upgrade worth it?

[sebackman]

Dear all,

I'm restoring a pair of original JBL SR4726a speakers (2226G + 2447/2381). I took a look at the filters in the JBL tech sheet and compared them to the newer SR4726X. They are completely different!


The older SR4726a has a 4ohm woofer and the older topology with resistor based CD compensation and the newer SR4726X has an 8 ohm woofer and a much cleaner filter topology.

I happen to have 4, 8 and 16 ohm 2226's available so I wonder if someone on this fantastic forum would know if the difference between the filters in the older "a" version and "X" revision would make it worth to build new filters and swap the 2226G's for 2226H's.
All the best
//RoB

[subwoof]

look close...the horns and drivers are different too...

[sebackman]

Hi Subwoof

They look pretty identical to me, except for "G" to "H" swap and filter. What am I missing. Please advise

http://www.jblproservice.com/pdf/SR-Series/SR4726A.pdf
http://www.jblproservice.com/pdf/SR-...es/SR4726X.pdf


All the best
RoB

[subwoof]

was thinking the change from 4726 to 4726A...too many versions to remember.

when you change the LF impedance the LF network components have to change - this usually means a small tweak in the HF section (esp the gain structure) and whatever design "upgrades" JBL has incorporated over that timeframe ( notably the use of speakons ).

if you have an older linear type amp ( and are running it passive ) then go with the 4ohm woofs.
if it's a newer digital power supply type then it doesn't matter.

sub

[sebackman]

Hi

I was not aware that there was a SR4726 with no "A" or "X".... Sorry.

What is in that box? 2446/2382? -Can’t find the techsheet.

However, the filters in the "A" and "X" are very different and the question still stands, is there any sonic gains from adopting the newer filter topology in the "SR4726X" while also changing to 2226H woofers. The woofers should sound the same so it is really about the Hi-pass filter and the CD horn compensation.

The drivers and the horns are the same and any sensitivity differences between the 2226G and the 2226H must have been factored in by JBL from the beginning.

I would have to build new filters but the component values are available in the tech sheet and the filters are rather simple with few components.

-And I do have a good pair of 2226H’s to swap in for the2226G’s

In short, do the SR4726X sound better/more “HiFi” than the SR4726A?

Do these boxes need a tweeter for HiFi usage, like a 2405 on top?

Thank you

//RoB

[sebackman]

Hello,

No one with experience of the older style SR filters compared to the newer version??

At least there are fewer components in the newer filter :-)

Anyone??

All the best
//RoB

[Rudy Kleimann]

Dear all, I'm restoring a pair of original JBL SR4726a speakers (2226G + 2447/2381). I took a look at the filters in the JBL tech sheet and compared them to the newer SR4726X. They are completely different! The older SR4726a has a 4ohm woofer and the older topology with resistor based CD compensation and the newer SR4726X has an 8 ohm woofer and a much cleaner filter topology. I happen to have 4, 8 and 16 ohm 2226's available so I wonder if someone on this fantastic forum would know if the difference between the filters in the older "a" version and "X" revision would make it worth to build new filters and swap the 2226G's for 2226H's. All the best //RoB

I know this is an old thread but still pertinent. Here are the differences between the original SR4700 Series, SR4700A Series, and SR4700X Series systems. I also included the SR700X Series which marked the end of the 4700 Series. The original SR4726 used the big 4" diaphragm/ 2" exit 2446J and 2380 horn. The 4 ohm woofer was selected to help match the output of the big 4" compression driver without having to use so much resistor padding in the high frequency filter circuit. The 4726A used the improved 2447J 1.5" exit driver and shorter 1.5" entry "Rapid Flare" horn for reduced driver throat and horn-induced distortion problems and improved time-alignment with the woofer. 1/4" TS inputs were replaced with Neutrik NL4 Speakon connectors and a full-range/biamp switch. The SR & SR-A series leaves the passive high frequency filter Network in series with the drivers when used in bi-amp mode so no external equalization is required to achieve factory response tuning from The High Frequency section of the speakers. The SR-X Series input and filter section was changed so that no internal passive filters were left in place when used in biamp mode, leaving the EQ duties to the user. This was to accommodate the new Digital Signal Processors such as Drive racks with their superior tuning and flexible control capabilities and factory tuning presets of EQ and time alignment designed to match the speaker systems. This allows two major advantages regarding amplifier requirements: The switch to an 8 ohm woofer in the SR4726X allows the user to connect two single woofer systems to the same amp Channel without overloading the amplifiers. It also permits the use of a mych smaller amplifier to drive the HF drivers in biamp mode while providing a direct connection to the HF compression driver for full electrical damping capability from the amplifier. The SR-X Series also did away with the carpet cover and rubber-coated grill protecting the cone drivers, replaced with Duratex spray-on finish and a full-front perforated metal grill. Later, the SR-X700 Series replaced all ferrite motor drivers with neodymium motor drivers on all cone and compression drivers, and the advent of the 3" compression driver in commercial PA use. A major decrease in weight, and much improved sound quality across the board compared to the 4700 Series.

[Earl K]

Good Info!!

Thanks for the overview!