What signal level is too hot for the F5?

[Zen Mod]

in original 2x100R are in paralell

that means - when you ditch one from group of two , you increase value to 100R

more precise - looking at Fig.6 in F5-om_sm-080527.pdf , ditch R5 and R6 , increase both R1 and R2 to 22R

 

[lorienblack]

Thanks Zen Mod - for your endless patience as much as anything else.

 

[Zen Mod]

naah ......

I'm neurotic and bully , comparing to Papa

 

[Nelson Pass]

Also, for those who want to take the edge off an F5 (or address stability issues)
I recommend a 4.7K input resistor instead of 1K.

Also, this is good if you think you might be overdriving the input, as in the
concern of the original poster.

 

[Zen Mod]

last time when I put 220Vac on input of my F5 , 4K7 resistor didn't help

 

[LucasAdamson]

I just remembered that I bought on eBay some 220R Panasonic metal film 3w, this would be the best solution Lorien, as then it would retain the same wattage absorption. The resistors are only 3W and should preferably be 5W for this purpose, but the Panasonic 3W Metal Films are pretty much as good as you can get for this purpose.

So, I have all the resistors you need for this job!

 

[lorienblack]

Well I changed the resistor values over, and for my set up it's problem solved. The focus has come away from the treble without the loss of detail the lower mids have come to life and there is more bass.

Thanks again to the diy community for your ceaseless aid, and to Lucas for the resistors. It's an all you can eat curry night for you next time your over

Nelson Pass rules

 

[lorienblack]

Well - if there's anyone out there on the end of this thread.

Since making the changes with resistors, the amp is running so cool you might even wonder if it's on at all. Some extra warmth on the fins behind the fets, but the rest of the heat sink is at room temp.

My initial impulse is to up the bias, as I have noticed a marked reduction in SQ when the amp is cold.

Is there a sensible limit to not go beyond, or should I tweak it up by degrees until it reaches a good operational temperature?

Many thanks in advance for your words of wisdom.

 

[Zen Mod]

check Iq and report here

only DVM don't lie

 

[lorienblack]

I checked IQ and it was out to lunch.

Checked the rest with DMM and now everything is as it should be.

Admin should remove the last couple of posts as they are of no use to humanity, we can all agree never to mention this again.........

Cough cough