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Old 20th April 2013, 11:05 PM   #1
rosario is offline rosario  Romania
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Default 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.
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Old 20th April 2013, 11:27 PM   #2
Zen Mod is offline Zen Mod  Serbia
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no need for preamplifier ........ if you are having potent source



what power you need generally for that speaker ?

then we can calc backwards what voltage swing you need
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Old 21st April 2013, 12:24 AM   #3
rosario is offline rosario  Romania
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I have yamaha da202 dac but in the future i want to use this dac to split signal to the F4 and also to aleph j. i want to use the F4 for 2245h and aleph j for jbl L16 decade speakers and bx63a crossover clone between dac and F4. is a good idea?
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Old 21st April 2013, 01:14 AM   #4
Zen Mod is offline Zen Mod  Serbia
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F4 is not having voltage gain
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Old 21st April 2013, 06:40 AM   #5
rosario is offline rosario  Romania
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i need to make an preamp for it in this cause? can i modified the bx63a to have some voltage?
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Old 21st April 2013, 11:27 AM   #6
bjorno is offline bjorno  Sweden
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Quote:
Originally Posted by rosario View Post
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:

b
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Old 21st April 2013, 12:26 PM   #7
scholl is offline scholl  United States
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Default subamp

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
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Old 21st April 2013, 01:16 PM   #8
SY is offline SY  United States
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Given the low Qts, this is not a particularly good speaker for open baffle without a lot of EQ.
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Old 21st April 2013, 09:56 PM   #9
rosario is offline rosario  Romania
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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?
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Old 22nd April 2013, 03:07 PM   #10
bjorno is offline bjorno  Sweden
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Quote:
Originally Posted by rosario View Post
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.

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