Thanks, again to you and Papa of course.
Maybe this article shed some light into the black hole, which is at the place of my brain.
(That light will be swallowed up without a trace, I'm afraid.)
Meanwhile, reborn J2 plays some of my favourites from Swiss minimal music experts, throgh my Quad ESLs.
I like it, and this is what matters.
Maybe this article shed some light into the black hole, which is at the place of my brain.
(That light will be swallowed up without a trace, I'm afraid.)
Meanwhile, reborn J2 plays some of my favourites from Swiss minimal music experts, throgh my Quad ESLs.
I like it, and this is what matters.
O.K..
As time goes by, this case seems to be of no effect, as input elco properties evolved. Sound is become better and better.
I usually don't believe snake oils and similar things.
But it is an experiential fact by me, electrolit condensators' sound is improving, as they began works.
Perhaps, I will implement a removable jumper underside the PCB at this point.
As time goes by, this case seems to be of no effect, as input elco properties evolved. Sound is become better and better.
I usually don't believe snake oils and similar things.
But it is an experiential fact by me, electrolit condensators' sound is improving, as they began works.
Perhaps, I will implement a removable jumper underside the PCB at this point.
@Jeff
A couple of things... I have the 20v trans here, told ya I wanted that volt. P
What is the max we want to run on the rails and also, one of the Semis is running a bit hotter than the rest. That one is up to 69-71C and the rest are 56-60C. I know the max temp is 150C, but I find it strange that the one is so much above the rest. When I put the new tranny, in I will double check the resistors, but I checked twice before I fired it.
A couple of things... I have the 20v trans here, told ya I wanted that volt. P
What is the max we want to run on the rails and also, one of the Semis is running a bit hotter than the rest. That one is up to 69-71C and the rest are 56-60C. I know the max temp is 150C, but I find it strange that the one is so much above the rest. When I put the new tranny, in I will double check the resistors, but I checked twice before I fired it.
The input JFETs are spec'ed at 25V (30V if you used SJ109s); the CCS JFETs at 40V. Each of them sees about 1/2 the rail-to-rail voltage. So that would say don't go any higher than +/-25V (or +/-30V).
However, Papa sez the Toshiba JFETs don't actually break down until around 40V, so there's at least some leeway available, depending on how much you want to trust Toshiba quality.
(The optocoupler only sees a few volts and is good for 70V anyway. The SemiSouths are good for 1200V, so no issues there.)
The higher you go the more issues you're going to have with heat, though. 70º on a SemiSouth wouldn't bother me, but I wouldn't want it much higher (remember there will still be a delta between the case temp and the junction temp).
Check the temps of the heatsinks right next to the JFETs. If that's also hotter on the hot one, then it's an electrical issue. If it's the same on all 4, then the hot one is a mechanical issue (thermal paste, screw torque, or something).
However, Papa sez the Toshiba JFETs don't actually break down until around 40V, so there's at least some leeway available, depending on how much you want to trust Toshiba quality.
(The optocoupler only sees a few volts and is good for 70V anyway. The SemiSouths are good for 1200V, so no issues there.)
The higher you go the more issues you're going to have with heat, though. 70º on a SemiSouth wouldn't bother me, but I wouldn't want it much higher (remember there will still be a delta between the case temp and the junction temp).
Check the temps of the heatsinks right next to the JFETs. If that's also hotter on the hot one, then it's an electrical issue. If it's the same on all 4, then the hot one is a mechanical issue (thermal paste, screw torque, or something).
Jeff,
would you please recommend values for 1.7A bias preserving original single ended flavour
would you please recommend values for 1.7A bias preserving original single ended flavour
Lowering R4 will increase the bias contribution of the current source, increasing the push-pull flavour a bit and decreasing the singled-ended flavour.
You can also adjust the flavours by modifying the ratio of the source resistors. If the total resistance stays the same then the bias will be the same.
Conversely, if you adjust the total resistance but leave the ratio the same the bias will change but the flavour will be the same.
Or at least that's my understanding of it.
Sweet!
Target values would be 0R28 and 0R42.
Caddock MP930s in 0R3 and 0R4 would be reasonably close.
Or you could use a pair of 3W Panasonic ERXs in parallel for each (2 x 0R56 and 2 x 0R82). That would get you much closer at the expense of not being quite as neat.
Cheers,
Jeff.
So, having got the heat under control on the one FET, I did the tranny swap. I now have the 300VA 20V from the 300VA 18V and where I was getting just under 22v rails, I now have 24.5V rails. I got my volt Jeff. 
It was like those magic $1000 cables it sounds sooooo much better now. lmao. Can I hear any difference? It's to late here to push it up, but this was never meant to be a window shaker anyway, I just wanted the damned volt.
It was like those magic $1000 cables it sounds sooooo much better now. lmao. Can I hear any difference? It's to late here to push it up, but this was never meant to be a window shaker anyway, I just wanted the damned volt.
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