We are working on the new GB as best we can. Need to revise the UBIB a little to make it easier to set test point. The sound is fantastic. PS and signal board are not the same so it's easier to work on.
I have noticed that depletion mode FETs are frequently used as constant current sources. How critical are these Fets? What parameters, besides IDSS make a 2sk170, 2sk117, J113, BF256 or a PF5102 the FET of choice ? With most JFETs being discontinued, its slim pickings and more freedom in choice would be nice.
Say you have DN2540 DMOS and a BF256 JFET in hand. How is best to use them in DCG3? The 2540 has generally good parameters but it does not mean that its performance, especially when for below 20mA, is as good as the BF256 JFET's for few mA CCS in a long tail source. But its noise is low enough and its dissipation high enough for use in the DCG3's output stage CCS. Or you want to constant current load a tube's plate. The 2540 is also high voltage suitable and you can't use the little JFET there regarding max voltage and dissipation needs.
Technically more hfe is better there yes. When having stronger samples prefer them right from the start. But not sure if audible differences will exist in cases of having already installed the respectably high four hundred range and then upgrade to the really high five or six hundred range between same type of transistors.
Between using BC560 and BC327 in the specific circuit there are plausible open loop gain curve differences both in amplitude and shape (I had shown simulations in the past). Hinting there could be subjective differences too. BC560 is the faster device, BC327 is the quieter device. Mainly quieter in the 1/f knee region at low frequencies.
Between using BC560 and BC327 in the specific circuit there are plausible open loop gain curve differences both in amplitude and shape (I had shown simulations in the past). Hinting there could be subjective differences too. BC560 is the faster device, BC327 is the quieter device. Mainly quieter in the 1/f knee region at low frequencies.
Yes it is
Just finished the second of mine. This one is almost dedicated for testing so most of the critical parts are placed in sockets.
Everything is perfect so far:
Bias : 111mA / 115mA
J3 bias: 4.6mA / 4.6mA
DC offset (without AD823) : 73mV / 66mV
Tried heatshrink in one of the pairs but had opposite effect in DC offset (rise +10mV). Funny but not of big importance I think.
Here we go again
Attachments
'Black is beautiful' as they used to say some time ago 
I think it's gonna be a long test period, BC560 vs BC327, uPA68H vs 2SK170, higher bias, lower gain, attenuators etc. In the end I'm gonna try the balanced configuration.
Waiting feedback from those who received the kit from the latest group buy.
I think it's gonna be a long test period, BC560 vs BC327, uPA68H vs 2SK170, higher bias, lower gain, attenuators etc. In the end I'm gonna try the balanced configuration.
Waiting feedback from those who received the kit from the latest group buy.
'Black is beautiful' as they used to say some time ago
I think it's gonna be a long test period, BC560 vs BC327, uPA68H vs 2SK170, higher bias, lower gain, attenuators etc. In the end I'm gonna try the balanced configuration.
Waiting feedback from those who received the kit from the latest group buy.
Will surely keep you busy listening and selecting. Nice to also see V1.1 legacy shunts there. Its certainly going to be a carefully customized config for your sonic detail preferences when you will be done with it.