A couple of more questions Nelson to help any member wanting to build a classic.
1. Any preference from your point of view on TO3 output devices, either MJ15022/023 or MJ21193/94?
2. What is the ideal Idss for Toshiba 2SK170BL for the input JFets?
3. For those JFets, what is the minimum matching accuracy you would want to see?
4. For the NO thermostat, will a 75 degC NO type mounted near top of output stage heatsink suffice?
5. For the 2K NTC thermistor also mounted to the heatsink, do you have a recommended brand / part number for this?
6. For an output stage to do 50watts per channel say, what is recommended minimum amount of uF per rail per channel for the PSU?
Regards,
Gary..
1. Any preference from your point of view on TO3 output devices, either MJ15022/023 or MJ21193/94?
2. What is the ideal Idss for Toshiba 2SK170BL for the input JFets?
3. For those JFets, what is the minimum matching accuracy you would want to see?
4. For the NO thermostat, will a 75 degC NO type mounted near top of output stage heatsink suffice?
5. For the 2K NTC thermistor also mounted to the heatsink, do you have a recommended brand / part number for this?
6. For an output stage to do 50watts per channel say, what is recommended minimum amount of uF per rail per channel for the PSU?
Regards,
Gary..
I'll chime in, Papa will correct me:
1. I don't care for difference
2. even GR will do; Iq per Jfet is (Vbe/150R)/2, so 2mA-ish
3. per Idss 0.5mA difference still acceptable, 0.3mA good
4. put it in between/near outputs, if 75C
5. whatever fancy you ..... small cap-looking ones, or those with mounting eyelet
6.50W means 35Vdc-ish rails; say that 33mF is a minimum per channel, per rail
1. I don't care for difference
2. even GR will do; Iq per Jfet is (Vbe/150R)/2, so 2mA-ish
3. per Idss 0.5mA difference still acceptable, 0.3mA good
4. put it in between/near outputs, if 75C
5. whatever fancy you ..... small cap-looking ones, or those with mounting eyelet
6.50W means 35Vdc-ish rails; say that 33mF is a minimum per channel, per rail
If one does not fancy heatsink work and drilling too much for TO3: https://www.mouser.dk/datasheet/2/308/MJW21193_D-1811680.pdf
They might even be a potentially better match for "greedy boyz budget" if a large stash for matching is needed.
They might even be a potentially better match for "greedy boyz budget" if a large stash for matching is needed.
Pic, you are a research hound.
Just a note for those wanting to have a go at building a Stasis revival amp using Nelson's new revised front end pcb as highlighted in post #1. On the schematic the contact shown as T (normally open) should be a normally closed type thermostat around 70 deg C mounted near the top of the output stage heatsink, Nelson has confirmed this to me by email.
Just a note for those wanting to have a go at building a Stasis revival amp using Nelson's new revised front end pcb as highlighted in post #1. On the schematic the contact shown as T (normally open) should be a normally closed type thermostat around 70 deg C mounted near the top of the output stage heatsink, Nelson has confirmed this to me by email.
Nice idea, but how many output transistors, originally they went from 3 per rail to around 20 per rail. I am only looking at 50WPC with 35 VDC rails based on the S200 with 3 output devices - but maybe a universal type output card could be done - would be easier with TO-247 type devices as well. I don't need hundreds of class A watts.
The heatsinks are drilled and tapped to accept up to 20 devices per channel.
So we make a pcb for 20 but you install as many as you want, eg anywhere between 8 and 20
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