I hope flg names the breed of the dog he shows as Avatar. There will be no confusion with the pic of Bella. Classic OES.
Hey DIYers. We've been forgetting to look under some important rocks. Think about Papa's efforts during the past year or so. The previous amp circuit was the F5-Turbo, which has the downside of thermal instability as the turbo-diodes heat up. With the temperature coefficient of the SemiSouth R100's perhaps this problem is resolved. Thus, Papa devised the quasi-comp R100 circuit with a transformer as phase-splitter. Now put turbo diodes in parallel with the source resistors.
I did a simulation of this. I need to put together a breadboard and see about thermal stability.
I did a simulation of this. I need to put together a breadboard and see about thermal stability.
Forgive me but.... Now we want transitors that act like triodes. Then we want to put them in tube like circuits. Or at least borrow heavly from tube circuits of yore. I guess it can't be helped. Since, a lot was discovered in audio during the tube age. Hard to come up with really new ideas. And nothing wrong with any of this. It worked in the past. Its just interesting to see how things have come almost full circle. From lets chuck out the transformers. To, hey, those transformer ain't as ugly the morning after........ Let me crank up my tube amp now....... 
Yup to which? "... we have already achieved something similar with low Rs. " or "Now put turbo diodes in parallel with the source resistors"
I was just exploring a thermal stability connection that hadn't been discussed.
somewhere earlier in the thread I posted little table showing excellent tempco of SJEP , which allows so simple , non compensated , bias arrangement
when I was Babelfishing Pa's J2 , I tried Rs in range of 0R1 ; from some other reasons I finished somewhat higher , but 0R1 was absolutely satisfactory temp. wise
when I was Babelfishing Pa's J2 , I tried Rs in range of 0R1 ; from some other reasons I finished somewhat higher , but 0R1 was absolutely satisfactory temp. wise
OK, now what do you think of this F6ish amp? At one point you were not impressed. So now with lower Rs, different bias and more burn-in time - what is your opinion?
Rush
ZM, buzzforb and lhquam. I am waiting for the dust of your tweaking to settle. I like to compound power amps and generate new mixes or hybrids with new sonic prints. I'll gladly assemble an F6 clone [for sale by gifted DIYers like you and others], operate it as a transconductance amp in conjuction with a Threshold S-150, an F5 or other voltage source amp. Count me in to buy your complete kit of components. You have the right stuff.
I have not changed my opinion much since post #1660 http://www.diyaudio.com/forums/pass-labs/216616-f6-amplifier-166.html#post3160159. Until I fix the JFET issue with the one channel I will not attempt to finalize my opinion. I have additional R100s on order to replace the JFETs in the channel that shows higher THD at high frequencies. I will select 2 JFETs for transconductance from the 4 available at that point.
Ilquam,
I have discovered an intersting experiment. Take cap and connect below Rs and listen. NOw reconnect cap to above Rs. It is like triode pentode switch on tube amp. give it a try if you can. Above Rs, soundstage grows in vertical plane vs horizontal pentode plane with connection below Rs.
I have discovered an intersting experiment. Take cap and connect below Rs and listen. NOw reconnect cap to above Rs. It is like triode pentode switch on tube amp. give it a try if you can. Above Rs, soundstage grows in vertical plane vs horizontal pentode plane with connection below Rs.
I have 2 Teaser-6 PCBs as shown in post #1452 http://www.diyaudio.com/forums/pass-labs/216616-f6-amplifier-146.html#post3155217 available for sale for $30 each plus shipping. I am not willing at this time to consider selling the entire chassis.