F4 power amplifier

lykkedk said:
Hi.

I am currius if someone have a pcblayout, which fit for the R0 4/17/07 ? - There is some issue with the 'IN' connection etc... ?

Also i would be very pleased, if someone could explain how much 'preamp' it would take to drive the f4 in a full balanced dual-mono block (4 pcb's + 2 torrids 2x18v 500VA).
It's not that i did not read this thread, and the 'mate for f4' thread also, but there is so much talk about voltage-swing / db-gain etc... that i am a bit confused.

I had been listening to the f4 at Steenoe's placed (I also mentioned this earlier in this thread), and i am in no doubt, that this amplifier sounds very veery good, and that i really would like to build one myself. I through have a slight feeling, that i would have a problem with my speaker/preamp setup, which was discussed in the 'mate for f4 thread' too...

Well, i have not so much acknogledge about the db / voltage-sving things, so please be gentle, if someone would try to explain this to me ! :cannotbe:

Jesper

Hi Jesper. As far as I remember you have a X-BosoZ? Did you try to raise the gain? Try to increase R18 and R19 on this sch. to 80k-100k. That will give you all the gain you need. 100K is 19dB gain in theory, but its much better to just try it out;)

"First build then ask"
I really like that one:cool:

Steen:)
 

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Nelson Pass said:
If you built it yourself, you can always scale the gain and power
supply up to get what you need.

:cool:


According to the service manual of the Aleph L , the gain can be adjusted by changing the value of the input resistor(s) 47K gives 0dB gain, 22K 6dB, and 10K 12db. With 5K we will get 22dB and I guess it would be too much. Or not?
With 7K5 will we get about 18db? Must be "just jake" to drive the F4? Can I go for it?

- What would be the effect of upping the supply voltage (to 70V may be) ?
:xeye: Yes yes i should try... and see the result . But I just would like to understand what I do.

Thx in advance
Manuel
 
Steenoe :

Hi Jesper. As far as I remember you have a X-BosoZ? Did you try to raise the gain? Try to increase R18 and R19 on this sch. to 80k-100k. That will give you all the gain you need. 100K is 19dB gain in theory, but its much better to just try it out

Sorry about that, its a 'normal' old fashion bosoz running unbalanced right now.. ;)

Well my bosoz is with 124ohm (13,5db in my setup) for maxium gain, but somehow i feel, it's not enough, that's why i asked if the x1 delivered the stuff somehow differently ?

Maybe i will take a closer look, at the aleph p 1,7, which seem's' like a bit more heavy, than my bosoz, and i think i could use my +rail from my bosoz to test it.

Jesper.
 
Ok then... I will try it out, whitin the next few day's guys ;) ... My only consern is, that the 124 ohm resistor is a seriel-resistor connected to a 500ohm potmeter, which i allready disconnected a long time ago.
But right now i am busy designing and etching a pcb for an 11vdc psu for my dac. :xeye:

Jesper ;)