F5 Turbo Builders Thread

That’s because Panasonic ERX is metal oxide (look at the data sheet).

This turns out not to be the case after all, even though I thought it was at the time. Panasonic just has a really confusing data sheet.

While the title of the data sheet is "Metal (Oxide) Film Resistors", the parenthesis evidently mean "for one of the two series described". If you look down under the part number explanation, you see ERX = Metal Film Resistor and ERG = Metal Oxide Film Resistor.

The construction picture further reinforces this:

High reliable metal oxide film (ERG)
High reliable metal plating film (ERX)

So apologies to Mouser for doubting their description. ;)

Cheers,
Jeff.
 
What the F""" am I doing wrong..

There I was listening to a bit of 'easy afternoon chillout' CD No4 so about 2 hours listening of the afternoon. Then Bang.....smoke and smell issuing from one side 'channel' of the power amp. The fuse did not blow (T4) and the other channel carried on playing. Jump to feet and off with the power. It was all to late, blown the coil out of the front of the newly aquired SAL full range driver....

This is not the first blow up Iv'e had.....errrr but this cost and may end my 25 year love affair with DIY. I am really pissed off that I can't see whats going wrong or what I'm doing wrong.

2 off 325va trainis 2x33v secondaries
48v rails
90,000uf per rail
DIY audio 5U case
250mv bias (low really:- driven by fear)
better than 5mv offset
Both bias and offset at a steady state after 4 hours on the bench prior to being pressed into service...as I recall.

Any ideas

I'll post better photos later...

I've found the issue with my blow up issues..(at long last). It was/would appear to have been a poor female spade crimp to the 0v to the rectifiers from the secondaries....I normally use solderd but used a crimp type for one of them. (I can't recall fitting it) A very slight movement felt between spade and wire. I could not pull the wire out of the spade but could push the wire into the spade crimp area by a tho or two and then little or no contact with the mating surfaces of the crimp and conductors...
 
He he... you'll have to post that on the "Why the hate for spades?" thread.... ;)

Ah...see where your coming from...

The spades are OK by me used them for decades without issue till now but the 'crimp' type if used got to be good...I recall we had a man come and do a drop test on our cable crimps known as the 9lb drop test...long ago now...power industry
 
Ah...see where your coming from...

The spades are OK by me used them for decades without issue till now but the 'crimp' type if used got to be good...I recall we had a man come and do a drop test on our cable crimps known as the 9lb drop test...long ago now...power industry

I usually solder them after I crimp them. I use an Amphenol crimping tool that does a pretty good job with most sizes of wire and spades. When properly crimped the connection should be gas tight and very low resistance. I've seen this type of connection used in older lab equipment that was in a corrosive (acidic) environment and we never saw any issues with the crimps. They also used Teflon insulated silver coated wire.
Even so, I solder them as well, particularly when they are in vital spots. I think I remember Papa Pass mentioning that he prefers to solder them as well.
So exactly how did a bad connection end up causing the amp to blow up? Have you figured that out?
 
i Have a question about my build of the F5 Turbo v.3 with irfp240 and irfp9240,
I had som issues with hum because of high ripple in psu,
I modified the cascode board with too little Capacitance, and that was the problem, I belive,
but before I got to that conclusion, I built a Regulator for the whole amp and all ripple went away, and hum disapeared, it sounds really good i would say, but my question is, if the
regulator with big 2sc5200 and 2sa1943, will decrease the sound quality details and so on, or just a matter of taste for everybodys own preferance ?
i have 20000uf before each regulator and 68000uf after.
and experience on this. ?
 
Congratulations on getting your F5 T V3 running! I built F5 V3 monoblocks with separate CLC power supplies. I did not use the turbo diodes. I have no hum at all. I am using Jensen input transformers as well, so that I can run single ended or balanced.

Regulated supplies should work fine if the regulators are stable and you can get rid of the heat generated by the series pass transistors. As far as sound goes- it’s all personal preference IMO. If you like it , it’s good!
 
I have 20VAC so 27.5 DC output. Am i have to change any part from official partlist because of 3-4v over suggested 24 voltage?

This is the F5 Turbo thread, which assumes 32V rails. It's the normal (non-Turbo) F5 that has 24V rails.

But short answer is: just the PSU caps. (You'll want 35V parts rather than 25V.)

Best to read the F5 Turbo doc here: http://www.firstwatt.com/pdf/art_f5_turbo.pdf

Cheers,
Jeff.
 
Sorry About that.

Now I love the amp.
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