So much for the protection circuit. I built up a lovely clone of Rod Elliots design but got the relay connections wrong. luckily it was on the bench being tested rather than with my B&Ws. Under failure condition the +Ve supply ended up being grounded by the relay. BANG and a nice fried PCB.
Back to the drawing board on that one.
Shame the PCB cost me nearly £100. Daad, I want some money for my birthday.
Back to the drawing board on that one.
Shame the PCB cost me nearly £100. Daad, I want some money for my birthday.
I have 2 original Rod Elliot PCB´s I can sell if you want ? They are not nearly so expensive.
And also some Kristian Aleph PSU pcb´s.
Best regards
Arthur
And also some Kristian Aleph PSU pcb´s.
Best regards
Arthur
Gain in F5CV2
I assume that with R5-R8=100 ohm/3W in my F5CV2 will give gain =15 dB.
To get a gain =26 db what value do I need for R5-R8??
Increasing the gain to 26 dB, will I still keep the distortion on an acceptable value?? Is there a "braking point" for increasing the gain without a acceptable lost in distortion??
Eivind Stillingen
I assume that with R5-R8=100 ohm/3W in my F5CV2 will give gain =15 dB.
To get a gain =26 db what value do I need for R5-R8??
Increasing the gain to 26 dB, will I still keep the distortion on an acceptable value?? Is there a "braking point" for increasing the gain without a acceptable lost in distortion??
Eivind Stillingen
Increase the feedback and you decrease the distortion.
Decrease the feedback and you increase the distortion.
There is no sweet point.
Decrease the feedback and you increase the distortion.
There is no sweet point.
Gain in F5CV2
What Andrew T wrote is not uknown to me:
"Increase the feedback and you decrease the distortion.
Decrease the feedback and you increase the distortion".
Steve has in his building guide increased R5-R8 to 220 ohms to get a higher gain.
The reason I asked about a gain of 26 dB is that I want my F5 to play together with preamplifier with a gain of 6 dB.
Will 220 ohm suits my wishes??
Eivind Stillingen
What Andrew T wrote is not uknown to me:
"Increase the feedback and you decrease the distortion.
Decrease the feedback and you increase the distortion".
Steve has in his building guide increased R5-R8 to 220 ohms to get a higher gain.
The reason I asked about a gain of 26 dB is that I want my F5 to play together with preamplifier with a gain of 6 dB.
Will 220 ohm suits my wishes??
Eivind Stillingen
the F5 has a maximum output of ~15Vac.
A gain of +26 in the F5 and another gain of +6dB in the preamp means that the sensitivity for maximum output signal is ~375mVac.
That is quite low for many stereo sources.
I find that old analogue gear has a maximum output of at least 500mVac and much digital gear has maximum outputs in the 1500mVac to 2200mVac range.
Typical gear feeding +6dB and +26dB gain stages will be turned down too often due to excessive system gain.
Read
http://www.diyaudio.com/forums/diyaudio-com-articles/186018-what-gain-structure.html
A gain of +26 in the F5 and another gain of +6dB in the preamp means that the sensitivity for maximum output signal is ~375mVac.
That is quite low for many stereo sources.
I find that old analogue gear has a maximum output of at least 500mVac and much digital gear has maximum outputs in the 1500mVac to 2200mVac range.
Typical gear feeding +6dB and +26dB gain stages will be turned down too often due to excessive system gain.
Read
http://www.diyaudio.com/forums/diyaudio-com-articles/186018-what-gain-structure.html
Can I increase the fuse value?
Hi
Last year with help from 6L6 and others I built my F5 power amp. Standard 24v PSU. It is hot to the touch after 30 min, I would say at least 50 degrees as I have small heatsinks. Also, I'm about to build and install a v3 power soft start circuit.
My question is, while I have the amp on the bench would it be OK to increase the mains fuse from 1.25 to say 2.5A, based on trying this with my other amps it can sound a little more lively. Am I right in thinking that even time delay fuses are in effect constantly limiting the current. I guess one analogy is squeezing a garden water hose.
Hi
Last year with help from 6L6 and others I built my F5 power amp. Standard 24v PSU. It is hot to the touch after 30 min, I would say at least 50 degrees as I have small heatsinks. Also, I'm about to build and install a v3 power soft start circuit.
My question is, while I have the amp on the bench would it be OK to increase the mains fuse from 1.25 to say 2.5A, based on trying this with my other amps it can sound a little more lively. Am I right in thinking that even time delay fuses are in effect constantly limiting the current. I guess one analogy is squeezing a garden water hose.
Don't believe stories that changing your fuse to 2,5A will make the sound more lively.
And it's not really safe to do so.
And it's not really safe to do so.
But he is in the UK, and needs a 1.25-1.5A slow.
Don't do it, it will have no effect at all on the sound.
Don't do it, it will have no effect at all on the sound.
Hi Walter, Nelson and 6L6, thank you very much for your quick replies 🙂
I will stick with the 1.25A, 250v I have.
Best regards
Steve
I will stick with the 1.25A, 250v I have.
Best regards
Steve
Need more warm sound from F5
Hi! Please can you help me?
I have just builded a F5 standard version i need to know if i lift R5 and R6 to obtain 100 ohm feedback resistor and also encrease R1 end R2 from 10 ohm to 22 ohm to preserve the feedback ratio ,can i obtain from my F5 more warm sound without stability/frequency problem?
Any advice would be greatly appreciated!
Thanks in advance and greetings to all of you again!
Antonio
Hi! Please can you help me?
I have just builded a F5 standard version i need to know if i lift R5 and R6 to obtain 100 ohm feedback resistor and also encrease R1 end R2 from 10 ohm to 22 ohm to preserve the feedback ratio ,can i obtain from my F5 more warm sound without stability/frequency problem?
Any advice would be greatly appreciated!
Thanks in advance and greetings to all of you again!
Antonio
Need more warm sound from F5
I forgot to mention that I also added P3 to optimize distortion or i hope to be able, using a spectrum analyzer to obtain a 2nd harmonic dominant rather than 3nd according to the project.
I hope someone can answer me.
Again, thank you!
I forgot to mention that I also added P3 to optimize distortion or i hope to be able, using a spectrum analyzer to obtain a 2nd harmonic dominant rather than 3nd according to the project.
I hope someone can answer me.
Again, thank you!
If you have P3, you only need to adjust it until you get the desired sound. Be sure to take notes on how many turns and what direction!
Last edited:
Hi! Thanks for your prompt reply!So...are you sure i need only to turn P3 to obtain 2° armonic dominant?
I remember long ago that Mr. Pass wrote something about the relation of R5 / / R7 and R1 (feedback) and its correlation with a more warmer sound.
Thanks 6L6.
Antonio
I remember long ago that Mr. Pass wrote something about the relation of R5 / / R7 and R1 (feedback) and its correlation with a more warmer sound.
Thanks 6L6.
Antonio
might sound stupid, but i wanted to ask what are some equivalents for 2sk170. i cannot find 2sk170 or something similar for f5 amp