Hi Nelson
A while ago, you mentioned it was time for a new front end.
At that time I suggested an F3 front end connected to output follower stage.
What do you think?
It obviously doesn't need to be an F3 clone, I am just proposing using lu1014d jfets at the front end (single ended).
So it would be lu1014d input stage (single ended) connected to the output follower stage.
To me, this idea could potentially turn out to be a real gem of an amp.
I see what I can put together as a possible working design.
A while ago, you mentioned it was time for a new front end.
At that time I suggested an F3 front end connected to output follower stage.
What do you think?
It obviously doesn't need to be an F3 clone, I am just proposing using lu1014d jfets at the front end (single ended).
So it would be lu1014d input stage (single ended) connected to the output follower stage.
To me, this idea could potentially turn out to be a real gem of an amp.
I see what I can put together as a possible working design.
Ok here is one more idea.
If you were to use lateral mosfets on the output board could the biasing setup be simplified further?
The other thing I have found with laterals is that they perform quite nicely at lower bias levels, so potential cost savings could be had or higher powered output could be gained depending on which way you wanted to go.
Just some ideas to think about (I never said they were good ideas).
If you were to use lateral mosfets on the output board could the biasing setup be simplified further?
The other thing I have found with laterals is that they perform quite nicely at lower bias levels, so potential cost savings could be had or higher powered output could be gained depending on which way you wanted to go.
Just some ideas to think about (I never said they were good ideas).
Hi,
you might just get away with 25Vac but 22Vac is certainly OK.
The 230:25Vac 5%regulation running on 230+6% mains voltage and no load gives
25 * 1.05 * 1.06 * sqrt(2) = 39.3V
The loss at very low current through the rectifier could be ~500mV giving a maximum of 38.8Vdc.
If this same transformer is connected to 240+6% mains then the maximum smoothing capacitor voltage is 40.6Vdc.
You need to know the normal mains voltage and it's tolerance range.
You need to know the transformer input and output voltages and the transformer regulation.
you might just get away with 25Vac but 22Vac is certainly OK.
The 230:25Vac 5%regulation running on 230+6% mains voltage and no load gives
25 * 1.05 * 1.06 * sqrt(2) = 39.3V
The loss at very low current through the rectifier could be ~500mV giving a maximum of 38.8Vdc.
If this same transformer is connected to 240+6% mains then the maximum smoothing capacitor voltage is 40.6Vdc.
You need to know the normal mains voltage and it's tolerance range.
You need to know the transformer input and output voltages and the transformer regulation.
From the BA2 article:
"Power Supply
... There were a variety of transformers given away with these chassis, and our goal is to have approximately +/- 25 volts on the supply rails. Voltages from 18 to 30 volts are acceptable.."
So, +/- 30v rails seems to be a maximum without cascoding.
I woud go with 2x18v AC.
"Power Supply
... There were a variety of transformers given away with these chassis, and our goal is to have approximately +/- 25 volts on the supply rails. Voltages from 18 to 30 volts are acceptable.."
So, +/- 30v rails seems to be a maximum without cascoding.
I woud go with 2x18v AC.
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Thanks your advise.
But form the BA2 article
"... Voltages from 18 to 30 volts are acceptable, and for transformers with secondaries much higher than 20 volts AC ..."
What's the meaning of "much higher than 20 volts AC" ?
If our goal is to have +/- 25 volts on the power supply rails, what secondaries volts should I use ?
Thanks.
But form the BA2 article
"... Voltages from 18 to 30 volts are acceptable, and for transformers with secondaries much higher than 20 volts AC ..."
What's the meaning of "much higher than 20 volts AC" ?
If our goal is to have +/- 25 volts on the power supply rails, what secondaries volts should I use ?
Thanks.
Nelson tends to use +/- 18v secondaries on the transformer which gives about +/- 23 or 24v rails, so that is probably the best choice.
He is saying I believe , not to go higher than +/- 20v for the secondaries on the TRANSFORMER which would give about +/-27v on the rails.
plus or minus a volt or so.
He is saying I believe , not to go higher than +/- 20v for the secondaries on the TRANSFORMER which would give about +/-27v on the rails.
plus or minus a volt or so.
Maybe thats for outputstage and special bias curcuit only
Might not apply to present pre/gain stage
Hi Aduiok,
you succeeded with BA-2! I tried first BA-1, when I wanted to change to BA-2 one screw fixing an output IRF 240 was damaged and I cut not put in an IRF 9240.
So I did not hear an BA-2 up to now
....... and I was eager to substitute the IRF240 with Semisouth thats the reason I stayed tuned to BA-1.
But BA-2 would be better for my 4 Ohm loudspeakers..... I will change for a try and get this damned screw out!
best regards Generg