Some of those white ones are plenty secure. I have some that are rated at 30 amps and the screw clamp is very secure and very solid. They either came from Mouser or Digikey. Not all of them are that heavy duty. The smaller black ones I also used were not rated as high amp wise, and with ring ends may be more "secure", but nothing is inside my amps tugging on them!
I didnt use them like you did between boards and power supply, I used them for the slow start assembly with the CL-60 devices.
Russellc
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Every part justifies itself by making it work. The 385's allow proper
operation into low impedances. The diodes protect the output Gates and
give symmetric clipping.
This used the Fairchild output devices and pot location assumes that P
channel Vgs is slightly higher than N. You can use other devices. If you want
to fool around, you can eliminate the cap coupling.
The Edcor transformer is steel core. If you want to use Jensen, then
set it up as autoformer and just drive the one tap above ground, letting
the other 3 coils create more voltage, for about X 4 (12 dB). If you
use other transformer, think about adjusting or eliminating frequency
compensation RC load to ground.
If you have a low impedance source you can eliminate the buffer altogether.
Nelson mentions you can skip the buffer if you have a low impedance source.In a later post he mentions <100 ohms.I am going to build this amp and have a Schiit Magni 2 headphone amp that has pre outputs (75 ohm) and enough drive to do this.My question is will I lose the "magic" of this amp by doing so? I know it will save me a few bucks but that doesn't matter.I just want to get it right.
The Jfets are very neutral. Any magic in that case comes from the transformer
being well driven. If the Schiit sound good into that load, then you are in
good shape.
The Jfets are very neutral. Any magic in that case comes from the transformer
being well driven. If the Schiit sound good into that load, then you are in
good shape.
HaHa----nice play on words,thank you both for your answers
dunno , didn't measured and didn't simulate that
however , speaker impedance isn't having anything with input impedance at xformer input ..... simply because output mosfets are nothing else than another buffer
if you have two pairs of Toshiba JFets - try with them , and try without them
if not - either go for Shiit's cojones .... or make another sort of buffer
I believe one Greedy Boy already made diamond buffer iteration , as far I remember - for F6 , which is similar - having iron in input
however , speaker impedance isn't having anything with input impedance at xformer input ..... simply because output mosfets are nothing else than another buffer
if you have two pairs of Toshiba JFets - try with them , and try without them
if not - either go for Shiit's cojones .... or make another sort of buffer
I believe one Greedy Boy already made diamond buffer iteration , as far I remember - for F6 , which is similar - having iron in input
I finally mounted my Teabag boards to there heatsinks last night. It's taken awhile. The left channel powered up ok with the voltage across the source resistor R13 reaching 597mv after a few of mins and the offset was settable to a few mv's. Unfortunately the right channel took close to an hour to reach 455mv across R13 but the offset was adjustable to near zero.
Elfishi has recommended to check the voltage rise over C3 which I will do later as it means removing the board from it's standoffs and bending the mosfet pins.
Any other guidance will be much appreciated.TIA
Elfishi has recommended to check the voltage rise over C3 which I will do later as it means removing the board from it's standoffs and bending the mosfet pins.
Any other guidance will be much appreciated.TIA
Taken from Tea-Bag's blog---"Here I make special note of my mistake in construction. Somewhere between looking at the datasheet, remembering the symbology as presented for DIP-6 devices and soldering it in, I put mine in backwards. The amp mostly worked, but it did not settle down it's bias to the .650v that is expected once it gets going. So, since the 4N35 was square and the dot on one side, the dot goes towards the curved back end of the optocoupler. "
Maybe your's is in backwards.
Maybe your's is in backwards.
Thanks for the reminder but I remembered Teabags blog and it was the first thing that I checked. It was in the right way round.
Hopefully I will get chance to do some checks tomorrow
I've just done a quick check and all resistors are correctly placed. Across C3 I have 10.21v on the left channel with 8.76v on the right.The voltage across R13 is 598mv left but only 245mv right.
As suggested by Zen Mod I swapped out the 4N35 but unfortunately this has not made any difference.
The voltage across the right R13 continues to rise very slowly but maxs out at 450mv after approx 45 minutes.
As suggested by Zen Mod I swapped out the 4N35 but unfortunately this has not made any difference.
The voltage across the right R13 continues to rise very slowly but maxs out at 450mv after approx 45 minutes.