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
And also i found 100R instead of 47R gate resistor.What kind of changes will happen to the sound?thanks
I just wanna learn what happens if i use 100R for gate and 15 R resistors instead of 10R. I am interested
15 ohms instead of 10 will change the negative feedback ratio. In this case increase also the NFB resistor from 47 to 75 ohms.
Doing so, you will increase the gain but distortion figure a little also.
Doing so, you will increase the gain but distortion figure a little also.
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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 ... 🙂
You believe a balanced input would be negative ? What about bridging ?
Maybe EUVL will post his ....
I suppose "balanced F5 with dual diff pairs" refers to balanced input only
The other option with bridging two F5 boards we know already
The other option with bridging two F5 boards we know already
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.
Ehh, wouldnt balanced input have higher gain/drive ?
Or is just the balanced signal line out that usually shows higher gain
Or is just the balanced signal line out that usually shows higher gain
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.