Brett,
if do not let a CCS let it lift to 285V, i loose direct coupling.
This is a phono preamp with dc coupling over 3 stages. Converted into a line amp with input transformer by the input selector switch (this is a real comlex switch, cut off from the pix i posted as i intended the pix for another purpose).
But you are right, on always can use a nice low voltage MosFET CCS and hook it in series with a resistor. The CCS determines the current and is within comfortable voltage limits itself and the resitor handles the voltage drop and heat dissipation. Resistor on top, CCS on bottom.
The 12A4 link you posted leadds to the 12B4A. Do you have a link to 12A4?
Jennifer Conelly in leather: good idea
. 🙂 but do i get you right? you would enjoy it? 😉
Sin bin isn't meant to be pleasant
... 🙂
if do not let a CCS let it lift to 285V, i loose direct coupling.
This is a phono preamp with dc coupling over 3 stages. Converted into a line amp with input transformer by the input selector switch (this is a real comlex switch, cut off from the pix i posted as i intended the pix for another purpose).
But you are right, on always can use a nice low voltage MosFET CCS and hook it in series with a resistor. The CCS determines the current and is within comfortable voltage limits itself and the resitor handles the voltage drop and heat dissipation. Resistor on top, CCS on bottom.
The 12A4 link you posted leadds to the 12B4A. Do you have a link to 12A4?
Jennifer Conelly in leather: good idea
. 🙂 but do i get you right? you would enjoy it? 😉Sin bin isn't meant to be pleasant
... 🙂
janneman said:
Maybe he better post a picture or a URL... i'm not quit sure either.
dave
Irony: dice posts a comment about how little off-topic is getting into the threads and now we are talking about female moderators which has only slight relevance to the 12B4 -- the B is somewhat a plan view?
12A4
Bernhard,
Don't know if it is still of any use to you but you can consider 12A4 and 12B4A as electrical equivalents.Think the 12B4A has controlled filament warm up whereas the A4 hasn't.
Also the 12A4 may have a slightly lower Rp (ain't sure) which I think is what grabbed your attention in the first place.
When I get my tube stuff back in Belgium I'll doublecheck it.
Greetz,
Bernhard,
Don't know if it is still of any use to you but you can consider 12A4 and 12B4A as electrical equivalents.Think the 12B4A has controlled filament warm up whereas the A4 hasn't.
Also the 12A4 may have a slightly lower Rp (ain't sure) which I think is what grabbed your attention in the first place.
When I get my tube stuff back in Belgium I'll doublecheck it.
Greetz,
12A4
Bernhard,
The only thing I could find for the 12A4 was via TDSL.
http://frank.nostalgiaair.org/short/054/1/137.pdf
and is the same one Frank has as a generic for the 2A3/6A3/12B4 etc. Looks like the Rp is higher, and the Ia lower than the 12B4.
Cheers
Brett
Bernhard,
The only thing I could find for the 12A4 was via TDSL.
http://frank.nostalgiaair.org/short/054/1/137.pdf
and is the same one Frank has as a generic for the 2A3/6A3/12B4 etc. Looks like the Rp is higher, and the Ia lower than the 12B4.
Cheers
Brett
OT
In answer to Jan and Dave's question,
No leather sorry.
Most recently seen opposite Russell Crowe in A Beautiful Mind.
Oh, Bernhard, under appropriate circumstances, I could get to like it.
In answer to Jan and Dave's question,
An externally hosted image should be here but it was not working when we last tested it.
No leather sorry.
Most recently seen opposite Russell Crowe in A Beautiful Mind.
Oh, Bernhard, under appropriate circumstances, I could get to like it.
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