F5Turbo Illustrated Build Guide

[bullitt5094]

Thanks! Just removed the jumpers from Q7 and Q8. On to plan "B". And thanks again everyone.

 

[AudioSan]

I suggest sticking with the original value of 4.75K for R27 and R28. That will give
you about 1/3 of the rail voltage across the jfets.

It realy no need to go down to 10V on the J-fets. With higher rails in the 40ish Volts i would agree,

 

[bullitt5094]

What would be the advantages of the higher voltage? Would it raise the gain of the amp overall?

 

[Dennis Hui]

My mistake: Apparently I couldn't divide 32 by 3. Somehow I thought it was higher.

There's arguably a bit more linearity with the jfets at a higher voltage. (Obviously
not too high since that's the whole point of the cascode). With 32V rails,
your original 10k should be fine even as long as you're not using V-grade jfets.

There's no change in gain.

 

[bullitt5094]

Thanks. I'll swap back to the 10K. Getting some desoldering practice. Not a problem if I can get it right.

 

[bullitt5094]

Testing the PS with the bulb tester. Nothing hooked to the PS output. With the AN-6224 I'm getting 33vdc from Gnd to V+. -33VDC from Gnd to V- and 66 volts from V+ to V-. Is that correct?



The bulb tester acted correctly. When bright for a second then almost off.

 

[Dennis Hui]

Sounds good.

 

[bullitt5094]

Awesome. Thanks!!

 

[bullitt5094]

So I've done all of these interconnects in 20ga Dueland wire. Should some of these be a larger gauge? Like the Output and Ground?

 

[Pheonix NJ]

You should find when you get biased up your rails will drop a little. 20ga really should be fine at the lengths you're talking about.
Real world use I tend to doubt anything would be changed by going to 18.

 

[jamesvhf]

sifted through many of these pages, has anyone build a pair of F5-t V3's ? ( thinking about it )

 

[rollingtube]

So I've done all of these interconnects in 20ga Dueland wire. Should some of these be a larger gauge? Like the Output and Ground?

On a side note: is there a reason to not turn the middle board by 180 degrees? Shorter and non-crossing wires as a result?

 

[bullitt5094]

Basically just didn’t think of it. Guess I should have done that and swapped the output boards positions too. Just rotate the whole assembly of the boards.

 

[cubicincher]

to jamesvhf #1271

Hello jamesvhf,


I have built F5T -V3-Monoblocks. They run on +-42.8V. Each Monoblock has a 1000 W toroid and some caps....

Excellent poweramps with my electrostatic Loudspeakers (Audiostatic ES300R)!
I use an active crossover for the sub at 80Hz. BA-3 poweramp is driving the subwoofer (JBL 15 inch).



Cheers
Dirk

 

[jamesvhf]

I You think 45v rails with 625va tx's is enough ?

I have a pair of Brand new Plitron 625va @ 2x30vac

or 3 x 33-0-33 @900va tx's

 

[cubicincher]

to jamesvhf #1275

Good morning jamesvhf,


a Plitron with 625 W and sec. AC output of 2x 30V AC will be absolutely enough. (My transformers are also 2 x 30 V AC out)

Rule-of-thumb: multiply your sec. AC V of the toroid with 1.3 to 1.4.
So you will 'land' anywhere between +-39V and +-43V DC after the cap bank.
I have a CRC- filter. It also depends on the values of your resistors between the caps.
Greets
Dirk

 

[bullitt5094]

Very impressive system Dirk. I don't normally associate a Class A with electrostatics due to the power requirements. Or with a sub amp for that matter for the same reason. I'm sure it sounds great. I'm now thinking Honey Badger to power a pair of OB subs to compliment my F5 and F5T that will power my LX-Mini system. This DIY thing never stops, does it? Or I hope it doesn't.

 

[cubicincher]

to bullitt5094

Hello bullitt5094,


once you are infected with this 'search-for-the-perfect-sound-virus' it is difficult
to come back to life without that...


Greets
Dirk

 

[bullitt5094]

I believe "Chasing the Dragon" is the proper terminology. But DIY Speaker Design/Construction (never thought I'd own a CNC router) and now Amps has taken that to a whole new level. And this is one of my inexpensive hobbies.

 

[AudioSan]

Very impressive system Dirk. I don't normally associate a Class A with electrostatics due to the power requirements. Or with a sub amp for that matter for the same reason. I'm sure it sounds great. I'm now thinking Honey Badger to power a pair of OB subs to compliment my F5 and F5T that will power my LX-Mini system. This DIY thing never stops, does it? Or I hope it doesn't.

in my humble opinion, the honey badger for a sub is just waist of a fantastic amp. Also, a 5 pair slewmaster would do the job better. For sub use you don't need anything more fancy then class D. I use hypex amps for sub use, and 5ch of honey badger for front, center and back (soon to be 7ch of honey badger).