F5 Turbo Builders Thread

[zimmer64]

These photos were taken at the time of build and all measured well and stable. I did run on the bench to .5v bias which as you can see is drawing 2.3amps per rail this is at 32vdc as I remember:- just to see.

Square wave was good too..1v input at 10k

I was very happy and ended running the amp at 250mv of bias well below a recommended 300mv....by members.

Doesn't the instruction say to set bias with the amp closed in order to get the proper temperature equilibrium?

 

[laverda]

Doesn't the instruction say to set bias with the amp closed in order to get the proper temperature equilibrium?

Yes..very important. Lid on. The photo was only to show my build and test of the circuits, not the final setup...

I would start and set the bias to 100mv, drop the lid and leave for 1 hour then check bias and offset again and re adjust bias to 150mv drop the lid and leave again for an hour.

After this time the temp is rising on the sinks and the bias is rising with it...possibly pushing 200mv. Re adjust bias to 225mv and lid back on leave for 15-30mins re check bias 'may be' over 250mv, so wind back the bias to below 250mv say 225mv, again lid back on and wait again, re adjust until a 'steady state' of 250mv bias and near 0mv offset as possible. I can normally get within 1.0mv offset. which is very good...

 

[6767]

hi2 all

will be pair (one per channel) this inductors good for CLC filtering in F5 (not turbo) power supply? 400VA 18+18

thank you



Rhombus L-522-08 Toroidal Transformer/ Inductor DC/DC Power Supply, 2mH 10A | eBay

 

[Zen Mod]

nope

what you need is either big air core inductor or also biggish iron core inductor

that one is for AC

 

[6767]

nope

what you need is either big air core inductor or also biggish iron core inductor

that one is for AC

thank you! so, I need something like this? Air Core Inductor Crossover Coils in the Speaker Components Department at Parts Express | 297


what power handling needed is 300 Watt per rail is enough?

 

[Zen Mod]

say 2mH is minimum , say 0R25 resistance is max.

 

[6767]

say thank you a lot

 

[6767]

seems it will be a good choice?

Brand New Hammond 195G10 Dc Reactor Choke 5Mh 10A | eBay

cant find air core with small resistance

 

[Zen Mod]

yup

 

[neno70]

psu v3 ?

hello, i saw here ( Stereo F5 Turbo V3 ) a realization of F5 v3 that on the psu uses 4x37v trsformator .. but did not have to be 2x24v as in v2?

 

[Zen Mod]

read this , few months minimum : http://www.firstwatt.com/pdf/art_f5_turbo.pdf

then , go back with questions

 

[6767]

is there any difference between 400VA 230V torroidal transformers with 18V-0-18V outputs and 18V-0-18V-0?

whats better to order for F5?

 

[kpsthakur]

Nope...2X 0-18 secondaries can be used a 18-0-18 if required...if by any chance you are using Diyaudiostore PSU V3, then go for 2X 0-18 version...easier that way

 

[6767]

thanks. going to order PCB form Jim's
Heavy duty power supply partial kit Pass amplifiers ! | eBay

 

[kpsthakur]

This may not be sufficient for F5T... the rectifiers would be low rated...strongly recommend go for the Diyaudiostore PSU..

 

[6767]

Sorry, didnt mentioned that going to build classic F5 20W 3Ohm, not turbo version

 

[6767]

and maybe in future configuration will be change from CRC to CLC (now cant spend about 100 dollars for pair of good Hammond DC choke).

 

[JeffYoung]

I'd use his other board:

Power supply PCB for DIY First Watt class A Power amplifiers ! | eBay

with some off-board bridge rectifiers:

GBPC3504 ON Semiconductor / Fairchild | Mouser Ireland

Rectifiers are somewhat noisy, so I like having them as far away from the input signals as possible. (See the insides of a production F5.) Having them bolt to the chassis bottom also keeps them much cooler.

Either will work, though.

 

[kpsthakur]

Oh ok...

 

[AndrewT]

..............with some off-board bridge rectifiers:
.....................

Rectifiers are somewhat noisy, so I like having them as far away from the input signals as possible. (See the insides of a production F5.) Having them bolt to the chassis bottom also keeps them much cooler..............

Keep the charging circuit from transformer secondary through rectifiers to main smoothing capacitors SHORT and COMPACT. Minimise LOOP AREA to reduce interference emitted to other circuits.