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
Apologies...
Does the square solder pad indicate the "base" of the transistor for Q7 and Q8 on the recent DIYaudio F5 turbo boards?
Is this marking common practice?
Thanks.
Does the square solder pad indicate the "base" of the transistor for Q7 and Q8 on the recent DIYaudio F5 turbo boards?
Is this marking common practice?
Thanks.
The square pad is the standard marking for pin #1 of a multi-pin package.
For polarized capacitors, it is the positive lead.
Yes,
the F5 will cool down if driving maximum sinewave output into a dummy test load.
But we use our F5 to drive music/audio waveform into speakers. The F5s run at a fairly constant temperature during all audio reproduction.
the F5 will cool down if driving maximum sinewave output into a dummy test load.
But we use our F5 to drive music/audio waveform into speakers. The F5s run at a fairly constant temperature during all audio reproduction.
Those are in the TO-220 package. Will they be ok with the heat and everything?
The TO-220 package works fine. Use a thermal pad for insulation or mica with thermal compound. Each output is operating well below its max at about 23w each.
In my build, during startup, the cap bank is intended to be disconnected from the F5T.
Can the F5T survive repeatedly having it's power rails rails switched on via relays with the power supply fully energized?
Thanks.
Can the F5T survive repeatedly having it's power rails rails switched on via relays with the power supply fully energized?
Thanks.
Can the F5T survive repeatedly having it's power rails rails switched on via relays?
Yes.
It's whether the speaker sees pulses during the switch on, or switch off, that should be your concern.
Yes.
It's whether the speaker sees pulses during the switch on, or switch off, that should be your concern.
Me.
Although I think it's more to do with the parallel devices than any change in the circuit...
Although I think it's more to do with the parallel devices than any change in the circuit...
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
So the bias on my one channel is floating down and cannot be set properly. The other channel is perfect. Could this be the thermistor? How would I test? Or should I just replace them? I am getting ready to smash this thing.
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.
This is a much quicker decline. It just slowly ticks down. The other channel does not do this. I guess I should let it cook for an hour or so. I am biasing to the article for a v2
Scott - as Vince suggests, playing with P3 will have more effect on the sound than any change to the PSU. If it's quiet, don't mess with the PSU.
sts9fan - If you turn it on and don't touch it for 1 hour, where will the bias be?
sts9fan - If you turn it on and don't touch it for 1 hour, where will the bias be?
be sure that all NTCs ( on both channels) are mounted exactly in same fashion
only then you'll have same temp. vs. Iq behavior
only then you'll have same temp. vs. Iq behavior