EUVL built balanced/bridged version of F5 more than a year ago - this is a big thread, but I'm sure it won't be hard to find his version.
Hello
I'm planing to build a balanced input X-ed F5 with multiple output MOSFETs .
But right now I'm in half way to have all the (exotic) parts , PC boars etc .
In case if I will have offset or any serious problem I can't solved I will go with balanced input bridged F5 .
Right now I can not write more , probably when I'm finished or will have some experience to report .
But it is possible to build such a amplifier !!!
Greets
I'm planing to build a balanced input X-ed F5 with multiple output MOSFETs .
But right now I'm in half way to have all the (exotic) parts , PC boars etc .
In case if I will have offset or any serious problem I can't solved I will go with balanced input bridged F5 .
Right now I can not write more , probably when I'm finished or will have some experience to report .
But it is possible to build such a amplifier !!!
Greets
You can easily build a balanced F5 with dual diff pairs.
Who wants the glory of posting the schematic?
That's if you think that the dual diff pairs sound ok!
Who thinks what on this?
And, the poster I responded to already had balanced output from his source, so no need for the diff pairs!
_-_-
Yes , only 600+ pages to go thru ...
That's if you think that the dual diff pairs sound ok!
Who thinks what on this?
And, the poster I responded to already had balanced output from his source, so no need for the diff pairs!
_-_-
You believe a balanced input would be negative ? What about bridging ?
You can easily build a balanced F5 with dual diff pairs.
Who wants the glory of posting the schematic?
Maybe EUVL will post his ....
The gain of the JFET section is:
(2k2 || P1)/(R1 + 1/gmQ1), NP used a nominal 20mS for Q1, so the gain boils down to 600/60=10. So if you don't have 10R and have to use 15R the gain is going to be a tad less. You'll also find that JFET's vary quite a bit in their parameters.
Erno Borbely has written several articles on JFETs -- these 2 are required reading:
http://www.borbelyaudio.com/adobe/ae599bor.pdf
http://www.borbelyaudio.com/adobe/ae699bor.pdf
There's been a bit of controversy over the wattage of R1,R2. Remember that there's a voltage divider between drain of the output MOSFET's, (R5 || R7) and R1, so if you are going to crank this amplifier to 25W, R1 can heat up quite a bit. 1 Watt minimum here.
A balanced output (that is, coming from the source) will have a + phase and a - phase. So if you have that, you can drive two identical amps one from each phase and connect the load to the "+" terminal of each amplifier - instant "bridged amplifier".
IF you only have an RCA output, you will need a way to generate a "+phase" and a " -phase " so that you can bridge the amps.
Diff pairs are only one way to do it. There are some real issues with diff pairs.
_-_-bear
like with every other known gain stage .
besides - even plain vanilla F5 have diff pair at input
Hi umut1001,
Using 15R instead of 10R will reduce the Idss (see fig 4B, page 28 of Borbelly Part 1) of the jFET.
At full power, the 100 ohm resistor gets up toward 2 watts,
14v * 14v / 100 ohms
Hi Nelson,
Are you referring to a gate resistor or the feedback?