F5 Turbo Builders Thread

[vdi_nenna]

I have built 5 and working on number 6.

Why?

 

[buzzforb]

Testing. Helping others. Latest one was traded for drivers.

 

[BigE]

there is some reading on Linear Audio site

Online Articles

http://tinyurl.com/ocf6c67

That's an excellent article. Thanks!

 

[leif christensen]

just one Q?
I´d like to raise the input impedance of my F5Tv2 to 100K
can this be achieved by changing R2 to 100K?
or will I need to change more components, R1?
best
Leif

 

[Zen Mod]

just go for it

 

[leif christensen]

thxs
any disadvantages?
I want this because a TVC will drive both the F5T and a 300B amp in parallell
on the same output
the 300B has a grid choke on the input
best
Leif

 

[Zen Mod]

no disadvantage

 

[leif christensen]

thxs a friend says maybe more noise, but will try
best
Leif

 

[Zen Mod]

I believe you'll hardly hear any difference between 47K and 100K

 

[leif christensen]

good
again, thxs
have a nice day
best
Leif in 30C summery Norway

 

[leif christensen]

hmmmmm
since I have such great experiences with chokes;
can R2 be replaced by a grid choke? looks similar to a tube amp input.....
best
Leif

 

[Zen Mod]

yup

 

[leif christensen]

fantastic!
thats gonna give much more harmonics and smoother sound

will 8000H 1,8mA typical grid choke do?
best
Leif

 

[Zen Mod]

it will do , if you can keep it away from mains

 

[leif christensen]

ha-ha
I´m really surprised nobody has thought of this before!?!
at least they haven´t told anyone...

best
Leif

 

[AndrewT]

thxs a friend says maybe more noise, but will try
best
Leif

no more noise.
The amplifier sees the much lower source impedance.That source impedance determines the input noise of the amplifier.

If you remove the source and power on the amplifier, then the amplifier sees the 100k or 47k and this now becomes the input resistance and you WILL HEAR NOISE.

BTW,
get a new friend, your existing one is doing you no favours.

 

[Erlend Sæterdal]

thxs a friend says maybe more noise, but will try
best
Leif

Higher impedance is always more noise . You are perfect right.

 

[leif christensen]

No noise when I forgot to hook up TVC and input was open
Best
Leif

 

[AndrewT]

when you listen to music or audio files the Source must be connected.

The Source impedance is so much lower than the input impedance that noise is dominated by the much lower Source Impedance.

 

[Erlend Sæterdal]

when you listen to music or audio files the Source must be connected.

The Source impedance is so much lower than the input impedance that noise is dominated by the much lower Source Impedance.

Sure ???