F5 Listening Impressions & Discussion

[umut1001]

Yes.Also bias is depend on your supply voltage of F5 amp.For example I am using 4ohm speakers and my supply voltage is +-21.5 volts.I increase bias to about 1,6A to get more Class A sound.The sound is better at high bias levels with my speakers.When i decrease it the sound goes worse.I can hear it easily

 

[hesener]

Hi Umut1001, do you have high or low efficiency speakers? And, are you listening really loud or not so much? Reason being that low-eff speakers and high volume will cause a larger swing along the transfer curve, and consequently the impact of the bias setting will be more important compared to e.g. using horns at 100dB/W and low volumes....

 

[bear]

with low efficiency speakers one is likely clipping the amp on peaks all the time.

a scope might reveal some of the clipping incidents...

_-_-bear

 

[markofka]

Hey,4 sure performance is itighlty independant from speakers.Mine are 6 ohm bass 92-97db,4ohm 90db mid,8ohm treble 92db.SO very difficult to match,but i got very good performance with my hiraga le monstre 13vdc and 0,6A And i can make much worse performance with 1,5A and F5. Who can explain this? I guess it's all about schematics,parts,psichology and some other 100 reasons...
I also must admit,when i used IRF with 50ohm feedback resistors amp was analytical,now with 65ohm it's "like tube sound" i guess it's because distortion and changed harmonics,and cheap paralleled resistor...

 

[umut1001]

Hi Umut1001, do you have high or low efficiency speakers? And, are you listening really loud or not so much? Reason being that low-eff speakers and high volume will cause a larger swing along the transfer curve, and consequently the impact of the bias setting will be more important compared to e.g. using horns at 100dB/W and low volumes....

Hi.My speakers are about 20cm 92db german nokia and tweeter is 94db westra.I think VxI should be about 70watt max.I think F5 amp can not work as same as ab amplifiers.They can perform good with very low bias but F5 does not work well at low bias.(about 30-40ma)This is my practise.Thanks

 

[hesener]

I agree. Tried the F5 at 100mA bias, and on the scope there were significant cross-over distortions visible, no point measuring THD..... This amp will need at least 1A of bias, if not more , but that has been elaborated on in this thread enough

 

[tinitus]

but i got very good performance with my hiraga le monstre 13vdc and 0,6A

My mentor always claimed that his pepped up balanced Monster was the best amp in the world
Well, that was before FirstWatt saw the day of light

Whatever, your Monster is a fine amp, if your speakers are right
Which they seem to be in your case
Maybe you just have the perfect synergy match with your Monster
Such will be hard to beat

btw, Monster is classA too... 8watt, and originally designed to sound like the best single ended triode tubes

If you want a direct replacement you might need the FirstWatt J2

 

[Andersonix]

.....At the same time, the output devices interact, and when the bias gets lower and lower you may drive the lesser-conducting device into a part of its transfer curve where it gets starved for current - consequently, producing probably more distortion than the (DC) bias point would indicate......

I think it's almost intuitive that performance goes down (distortion increases) with reduced bias. But I went back and read NP's 'Leaving Class A' paper again, and it suggests performance (low distortion) keeps improving with increased bias (for class A and AB), and it doesn't go down again at any point, so no sweet spot?

 

[Blues]

The sweet spot will then be where your pockets are allowed to take you...re more powerful PS and bigger heatsinking....

 

[umut1001]

Hi.I connected 2xparallelled Silmic II 50v 1000uf to F5 amp(toshiba output) in series .Amp plays much smoother now.It was playing hard before.I can listen forever with them now

 

[Tea-Bag]

huh? Where?

 

[umut1001]

Hi.Here is the picture of my trying

 

[bobodioulasso]

A diagram would be better.

 

[umut1001]

There is no need to diagram.Just connect silmic capacitors to tweeter in series and you will see that the sound becomes smoother.(IMHO) Thanks

 

[a.wayne]

 

[Renron]

There is no need to diagram.Just connect silmic capacitors to tweeter in series and you will see that the sound becomes smoother.(IMHO) Thanks

Wouldn't that change the phasing? 90 degrees?
Scratches head trying to remember.......

Ron

 

[umut1001]

No it does not.Firstly you have to learn to calculate filtering at speakers.There must be a capacitor in series tweeter everyway.(if you do not use active preamp at the input of the amplifier)
For example if you have 4.7uf capacitor and if you connect 2000uf capacitor in series it is the formula
1/C(equivalent)=1/4.7 + 1/2000 = 4.68uf nearly changes nothing at phase

 

[umut1001]

And my connection was just a trying that how elna silmic II capacitor sounds.Not a proffessional and completed project.And also for burning in the capacitor for our pcm2702 headphone dac project(It has ad8397ardz opamp and 2x1000uf elna silmic II capacitor at the output)

 

[Renron]

Umutt1001,
Thanks for the explanation.

Ron

 

[cviller]

Seriously umut, this is just plain silly. Your calculations are right, but that only shows that the silmics can do nothing but perhaps a colouration of the sound... find a silmic to replace your 4.7uf and you might start hearing "silmic sound", but not like this.