I knew that the max output is not continous and therefore not the maximum temps all the time but not that the standing idle bias was the highest temp point. The SA/1 delivers 160w into 8 ohms and 300 into 4 ohms with a standing bias of 240w. I was adding output power to the idle power but thinking about it I can see that is not the case after all.
That makes three things you guys have set me straight on. I Much Appreciate your feedback.
John
That makes three things you guys have set me straight on. I Much Appreciate your feedback.
John
The square pad is the standard marking for pin #1 of a multi-pin package.
For polarized capacitors, it is the positive lead.
Those are in the TO-220 package. Will they be ok with the heat and everything?
Folks:
The power supplies in both of my F5T V3 monoblock amps are sporting 160,000 uF, consistent with Nelson's F5T design. The amps sound terrific, but slightly "thinner" than the Pass Labs Aleph 1.2 monoblocks they superseded. I'd like to address that issue and am considering adding another RC stage, probably with 90,000 uF (i.e., 45,000 uF per rail). My hope is that with a total power supply capacitance of 250,000 uF per monoblock, my F5T amps will have greater authority and presence without sounding bloated or slow.
I know this is DIY, where the mantra is "try it and see", but I'd appreciate any knowledgeable input as to whether the additional RC stage (.05R and 90,000 uF) is too little, adequate or too much for my purposes.
Regards,
Scott
The power supplies in both of my F5T V3 monoblock amps are sporting 160,000 uF, consistent with Nelson's F5T design. The amps sound terrific, but slightly "thinner" than the Pass Labs Aleph 1.2 monoblocks they superseded. I'd like to address that issue and am considering adding another RC stage, probably with 90,000 uF (i.e., 45,000 uF per rail). My hope is that with a total power supply capacitance of 250,000 uF per monoblock, my F5T amps will have greater authority and presence without sounding bloated or slow.
I know this is DIY, where the mantra is "try it and see", but I'd appreciate any knowledgeable input as to whether the additional RC stage (.05R and 90,000 uF) is too little, adequate or too much for my purposes.
Regards,
Scott
SRMcGee
What voltage rail are you working with?
I can't say whether its "enough" capacitance, as I really don't know if there is a point of dimishing return.
I'm using 56400uF per monoblock, and I don't think anyone that heard it has ever accused it of not having enough bass, and punch, nor is it slow.
I don't think you need the R when you add more. just add in the caps and its done.
But make sure you have something like a slow charge to charge up that bank when you first turn it on!
What voltage rail are you working with?
I can't say whether its "enough" capacitance, as I really don't know if there is a point of dimishing return.
I'm using 56400uF per monoblock, and I don't think anyone that heard it has ever accused it of not having enough bass, and punch, nor is it slow.
I don't think you need the R when you add more. just add in the caps and its done.
But make sure you have something like a slow charge to charge up that bank when you first turn it on!
Hi Scott,
Maybe you need to adjust P3 to hopefully get a more "fat" sound. Maybe lean toward 2nd harmonic, if it's toward 3rd?
http://www.diyaudio.com/forums/pass-labs/216616-f6-amplifier-436.html#post3516349
See post 4353.
Regards,
Vince
You can test without any thermistor at all, but you'll have to increase bias slowly and in steps.
How strong is the variation/where do you set it and how does it wander?
It is perfectly normal for the bias to go down as the amp warms up, this is how the thermistors work. You are supposed to keep twiddling the pots till the heatsink reaches a stable temp and the bias and offset are close to target values.
The biggest issue of running without thermistors is that the amp gets hotter and bias goes higher as the ambient temerpature rises, and reverse when it gets colder - so the bias setting is pretty much valid only for one exact ambient temperature value.
How strong is the variation/where do you set it and how does it wander?
It is perfectly normal for the bias to go down as the amp warms up, this is how the thermistors work. You are supposed to keep twiddling the pots till the heatsink reaches a stable temp and the bias and offset are close to target values.
The biggest issue of running without thermistors is that the amp gets hotter and bias goes higher as the ambient temerpature rises, and reverse when it gets colder - so the bias setting is pretty much valid only for one exact ambient temperature value.
