Perhaps I deserve to be called a fool. It was not meant to be mean or make light of all the hard effort put into this. I did find myself checking the store the the last couple of days. A lot of interest in this thread and the boards. Not to read the tea leaves but I was always curious if people were having issues testing - if that was the case we could all possibly learn from it.
Yes it would be better to have each tester sum up their experiences here and where they are in the builds at this moment. There are various amps working, but always, some small item isn't perfect, but that doesn't mean the boards are flawed. Also some don't use all the boards, etc.
I'm packing the boards into their bags as they will be sold as one item
I'm packing the boards into their bags as they will be sold as one item
Dark Alley talk. I had built 3 successful V2 builds and one channel of v3 with no issues. I also helped fire up a 4 amp that was a v2. all of these used TeaBags boards. 6L6 got the store boards and had some trouble. Kept burning fets. Was able to get one up and running and burnt it through torture test with his sig generator. Mark was kind enough to send a pair my way for testing. I fired it up with no issues. made the amp clip at 1K,10K, and 20K. No issues. EVen hooked up the rats nest wiring wrong, cooking small 10uf coupling capacitor on signal board. Blew the damn thing up like an M80. Replaced it, plugged the rails up properly, and all was fine. I have yet to find anything to worry about, but it might be wise to use C3 in V2 and above. It simply cuts off some of the bandwidth in the amp to reduce possibility of oscillation. F5 is WIDEband amp. I have not seen any oscillation as of yet. Will do final testing this weekend by hooking it up with cap as load. Its an attempt to make it oscillate. F5T is advanced amp simply because of power levels involved. But if you are careful, follow instructions, all should be fine. A variac is an indispensable item to have if serious about amp building. You can find them for very good prices used. It allows for a great deal of safety in the turn on procedure.
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I have let the smoke out of my V2 a few times. Oscillation for unknown reasons twice -- the was fixed by larger value gatestopper resistors and the addition of the compensation cap from gate to rail. (Shown in the V3 schematic)
The last time was during a torture test, feeding it a 40kHz squarewave of sufficient amplitude to drive the amp just under clipping. Don't do that.
I strongly suggest using the compensation cap (1000pf) in all builds and increasing the gatestopper resistors to 470ohm or thereabouts. (I'm using 680ohm, on the suggestion of Wayne Colburn)
The build guide is being worked on at this very moment.
The last time was during a torture test, feeding it a 40kHz squarewave of sufficient amplitude to drive the amp just under clipping. Don't do that.
I strongly suggest using the compensation cap (1000pf) in all builds and increasing the gatestopper resistors to 470ohm or thereabouts. (I'm using 680ohm, on the suggestion of Wayne Colburn)
The build guide is being worked on at this very moment.
I have had one fired up and tested, but no music ever played through it. Layout will be important.
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