Thanks, I also found a thread on DIYAudio:
http://www.diyaudio.com/forums/solid-state/2080-dc-filter.html
I'm in electronics for many years, but never heard of this, but hey, never needed transformers over 500 VA.
Thanks, I also found a thread on DIYAudio:
http://www.diyaudio.com/forums/solid-state/2080-dc-filter.html
I'm in electronics for many years, but never heard of this, but hey, never needed transformers over 500 VA.
I had the same problem and used this for 1500va and it worked well.
I used 2x6800uf and 4x1n5408 if memory serves me well
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DC protection of speaker is different than DC protection of toroidals and r-core transformers.
I have done it for ones of my class AB amplifier and yes, it stopped that intermittent buzzing from transformer. See more detail s with pics here. It was taken from Rod Elliot's article - Mains DC and Transformers
I have done it for ones of my class AB amplifier and yes, it stopped that intermittent buzzing from transformer. See more detail s with pics here. It was taken from Rod Elliot's article - Mains DC and Transformers
bridge snubbers
Hi Walter,
I saw your finished amp in the "pictures of your diy pass amplifier" thread. Very nice job.
I see you used snubbers on your bridge diodes. Can you comment on the values you used?
Also, you used 0.22R mosfet source resistors rather than the 0.5R in the schematic. From my understanding, the lower value will result in a smaller jump in bias when the diodes conduct. Is this why you chose the smaller value?
Making some progress...
PSU is build and tested, it's modular, it can be removed as a whole from the amplifier.
All the nasty and noisy rectifiers are shielded under the transformers...
ZM told me the rectifiers would be warm
All PCB holes in the sinks are drilled and tapped. All transistor's are matched and selected, just like the resistors.
So now the nice part of populating the PCB's starts..."bestücken" yeah..
My last pic with the green terminalblock...what is better? Tinned leads, or just with the bare copper leads ???
What gives the lowest contact resistance? Also in long term?
Or should I not use them at all, and solder the leads directly on the PCB's?
But then my PSU is not so modular anymore
Walter
Hi Walter,
I saw your finished amp in the "pictures of your diy pass amplifier" thread. Very nice job.
I see you used snubbers on your bridge diodes. Can you comment on the values you used?
Also, you used 0.22R mosfet source resistors rather than the 0.5R in the schematic. From my understanding, the lower value will result in a smaller jump in bias when the diodes conduct. Is this why you chose the smaller value?
What he said, or 2 X 500VA if you are a megalomaniac like me.
If you want to push the envelope on the V3 and go for 100W I would go for 2 X 800VA or 1000VA with monobloc chassis. Even more nutz!Hi Walter,
I saw your finished amp in the "pictures of your diy pass amplifier" thread. Very nice job.
I see you used snubbers on your bridge diodes. Can you comment on the values you used?
Also, you used 0.22R mosfet source resistors rather than the 0.5R in the schematic. From my understanding, the lower value will result in a smaller jump in bias when the diodes conduct. Is this why you chose the smaller value?
Hi Alazira,
I used 100 Ohm and 100nF/63V for the snubbers.
The 0.22 Ohm is appropriate for my 2SJ201/2SK1530 output devices, cause they handle 'only' 12A max. I saw it in the F5X thread.
An additional advantage is that with 1.25 A there is idle only around 0.3 V over the resistors and diodes, which is a value Papa named to be safe...
My rule of thumb: You can't have too much transformer VA rating! Chokes are good too, so leave some room!
At the point it is too heavy to move, then it is just right.
If you are using two transformers, has anyone thought about using one transformer per rail? It would give the rail a chance to recover before the next transient.
Rush
Hi Walter,
I was re-reading the F5Turbo document and noticed this part:
As you can see, NP biases at only 0.8A (0.4V/0.5R) standard and 0.6A "fraidy-cat" for the fairchild devices, while you have biased at 1.25A for the lower Amp rated Toshiba's... I hope there is no problem.
ITs not about the bias amount, but the V drop across the source resistors that cause the diodes to turn on. For instance, 2A across .2R source resistors, would cause a Vdrop of .4V across the diode, keeping it within the SOA as written above. In this way you can manipulate just how much bias you have through each fet simply by changing the Rs value. Of course you have to consider heat dissiaption and other such issues, but that is another converstation
I still believe the diodes would do better if they only turned fully on, when the output transient current exceeds the ClassA current.
That requires the Vrs to be <=300mV.
The result of this is that the ClassA performance of the F5T is not affected while the current stays below the ClassA limit.
The diodes pass when excess current passes to the load, i.e. the amp has transitioned into ClassAB and Iout > 2*Ibias
A consequence of this is that the diode does not turn on often and when on it is generally only for the short period of the transient.
This makes for near cold diodes. It may be that when set up like this that the diodes will not require heatsinks. This will become evident when playing your choice in music.
That requires the Vrs to be <=300mV.
The result of this is that the ClassA performance of the F5T is not affected while the current stays below the ClassA limit.
The diodes pass when excess current passes to the load, i.e. the amp has transitioned into ClassAB and Iout > 2*Ibias
A consequence of this is that the diode does not turn on often and when on it is generally only for the short period of the transient.
This makes for near cold diodes. It may be that when set up like this that the diodes will not require heatsinks. This will become evident when playing your choice in music.
http://www.diyaudio.com/forums/pass-labs/206240-f5-turbo-posted-56.html#post3065015
He says it better than I. I just thought this would be helpful to those who may not have seen it before.
He says it better than I. I just thought this would be helpful to those who may not have seen it before.