jbl 2245h amplified by F4

Hello people i want to ask if anybody know if nelson pass F4 in bridge can be the amplifier for jbl 2245h without an preamplifier ? I put the 2245h in open baffle and i guess the F4 doesn't have enough power or this 2245h must need an enclosure to sound?

Thx for reply's , greetings from Romania.
i need to make an preamp for it in this cause? can i modified the bx63a to have some voltage?

Hi rosario,

Here is an idea:



  • JBL_BX63.JPG
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2012-12-30 5:07 pm

Not sure how the F4 would drive that woofer. You'll have to try it to find out. Odviously you like low power amplifiers. In applications like this sometimes more power and damping sound better than a sweet little amp. As well all know synergy comes in all forms. YMMV
thx bjorno for this schematic , i tested in open baffle but it will have a enclosure. another thing about bx63a can i make the output balanced even the input to have some decibels more, it worth?

Agree, The driver is not well suited for an OB..What size and type of Box are you planning?

Regarding the Amplifier question:
Of course you can design a balanced output low Ohm buffer as you gain the double Voltage swing to feed the F4 but there would be an insertion loss at the F4 Receiver end if not made 'higher Ohmic' balanced to single end.
This is not a problem if you design a balanced input circuit using an Op-Amp like the already used TL07X amps in differential mode.