All the power stuff still connected with Abiko connectors, but once things are settled, I'll shorten the wires and solder everything together. 
Techically I think the signal wire is not coax but a shielded signal wire (Hypex made for NCore) but I'll try thin/twisted too.
Also on the power supply I have ready made tabs to connect/try additional caps.
Georg, you've been a great help with parts and advice - thanks!
Techically I think the signal wire is not coax but a shielded signal wire (Hypex made for NCore) but I'll try thin/twisted too.
Also on the power supply I have ready made tabs to connect/try additional caps.
Georg, you've been a great help with parts and advice - thanks!
Well I got my build about ready now.
Here's a picture, and some more can be seen here:
http://www.diyaudio.com/forums/pass...-your-diy-pass-amplifier-257.html#post3808301
Here's a picture, and some more can be seen here:
http://www.diyaudio.com/forums/pass...-your-diy-pass-amplifier-257.html#post3808301
Attachments
No meaningfull listening impressions yet I'm afraid. I suppose pretty much what others are hearing..? What I heard through the desktop speakers was nice and quite engaging but that in it's self doesn't say much. I'll still have to listen properly with the amp in my main rig and try the harmonics tuning. Then after settling in with the prefered ajustments it will be compared to my Hypex NC400s and to my VAC monos. I post impressions then. 
Dimikasta: basic WBT (0730) speaker terminals.
Dimikasta: basic WBT (0730) speaker terminals.
Last edited:
Well I got my build about ready now.
Here's a picture, and some more can be seen here:
http://www.diyaudio.com/forums/pass...-your-diy-pass-amplifier-257.html#post3808301
Very beautiful indeed! Congratulions
Greetings,
i need help with my offset setting.
The bias pots P2 bias well over 1.2V and there does not seem to be any problem there.
On one channel, Q1 is at about 1.153V. If I turn the offset pot (P1) to max, I cannot get higher than 1.153V on Q1
On the other channel, Q1 is at about 1.212V and turning the offset pot(p1) to min , I cannot get Q1 to lower than 1.212
I'm using semi outputs with 1 led for bias and offset.everything else is vanilla F6.
Is there any way to get both readings to 1.2V?
Perhaps I am missing something here but every suggestion will be considered.
thanks.
i need help with my offset setting.
The bias pots P2 bias well over 1.2V and there does not seem to be any problem there.
On one channel, Q1 is at about 1.153V. If I turn the offset pot (P1) to max, I cannot get higher than 1.153V on Q1
On the other channel, Q1 is at about 1.212V and turning the offset pot(p1) to min , I cannot get Q1 to lower than 1.212
I'm using semi outputs with 1 led for bias and offset.everything else is vanilla F6.
Is there any way to get both readings to 1.2V?
Perhaps I am missing something here but every suggestion will be considered.
thanks.
Thanks for feedback
I may have miststated my concerns.
on 1 channel, I have bias set to 1.2 1nd 1.183V on the semis and 0 offset. all Ok except that is there any way to get both at 1.2V or is this a matching problem I have to live with?
on channel 2: I have 1.000V and .953V bias on the semis. The problem here is the offset. The offest pot ranges from about -13V to -11V from out to G. Obviously a problem here but I don't know where to troubleshoot. Is it possible that one of the buffer fets is fried?
I may have miststated my concerns.
on 1 channel, I have bias set to 1.2 1nd 1.183V on the semis and 0 offset. all Ok except that is there any way to get both at 1.2V or is this a matching problem I have to live with?
on channel 2: I have 1.000V and .953V bias on the semis. The problem here is the offset. The offest pot ranges from about -13V to -11V from out to G. Obviously a problem here but I don't know where to troubleshoot. Is it possible that one of the buffer fets is fried?
difference in gate voltage is irrelevant , in this case ; it's relevant only in troubleshooting purposes , when needed
xformer is between input Jfets and outputs , so no influence
clarify -13 and -11 - what that means - output node voltage (DC offset ) or what ?
what's voltage you can set on bias pots - upper one ref. to +rail , and lower one ref. to -rail ?
check those LEDs
Last edited:
First off, bias is in A not V. This could be confusing to those helping. Bias is measured across the source resistors of the fets and is determined by voltage divided by resistance. I am sure you know this, just stating the obvious. In my experience with the F6 one half can have a tendency to "steal" current/bias voltage from the other half. Generally this occurs when biasing up the top fet before the bottom fet. When biasing my F6 toys, I always bring them up together, adjusting both equally and at the same time. Remeasure bias on the second channel. Ignore Vgs. It is irrelevant, at the moment. Once you find your bias amount, try adjusting the bias of the top fet down and see if the offset comes into line. If you try this and th offset increase rather than decreases, then the issue is with the lower fet. You may have to try a Blue LED for higher available bias voltage on the lower fet if this is the case. You could also use a zener.