Help! Anyone in Seattle area willing to take on a challenging F5T issue?

[SirByrd]

Both amps corrected, just need to find a day that I can spend some time getting them warmed up and biased, that day was not today, and won't be until next week likely.

 

[powerflux]

Good job!

 

[SirByrd]

120v in, ~.32v across source resistors, .8A draw from the wall. 5mV of dc offset. Heatsinks are about 100F 37C with the top on. Music plays.

 

[vdi_nenna]

There you go!!

 

[SirByrd]

Would a 2.5A slo-blo fuse be enough? I think Papa calls for 5A in the article but that was for stereo? I'm not sure.

 

[Zen Mod]

what's VA of your xformer and which NTC you're using for primary ?

 

[vdi_nenna]

Smaller, in this case, is better than too big, but expect to lose a few. These amps can draw lots of current. Have spares. You already have two pieces of the ohms law equation, voltage and watts. You just need to know the total peak current draw that's safe.

 

[SirByrd]

Pegs my 15A meter at start up. Would like to avoid installing a CL30 since it's pretty cramped. Doesn't seem to blow the fuses, I think I'll just keep in the smaller fuses.

 

[SirByrd]

what's VA of your xformer and which NTC you're using for primary ?

400, and I have some CL30s but I didn't use them on my normal F5 and it was just fine.

 

[Zen Mod]

well then

I heard this one is pretty good , as fuse , too

 

[Nelson Pass]

120v in, ~.32v across source resistors, .8A draw from the wall. 5mV of dc offset. Heatsinks are about 100F 37C with the top on. Music plays.

Now doesn't that feel good?

 

[6L6]

Doesn't seem to blow the fuses, I think I'll just keep in the smaller fuses.

It will, in time.

 

[MASantos]

Did you build those cases yourself or are they available somewhere? They look great!!!

 

[SirByrd]

Did you build those cases yourself or are they available somewhere? They look great!!!

I designed them myself, including custom machining done to the Conrad heatsinks.
If you want to replicate them I can PM you the front panel express files, which should also work at their parent company which is based in Germany (cheaper shipping for you)

 

[MASantos]

Thanks for the info, I have something very similar designed for a future project, if it were available on the shelf would be much cheaper.

 

[SirByrd]

Thanks for the info, I have something very similar designed for a future project, if it were available on the shelf would be much cheaper.

Yeah, with heatsinks it was about $1400 for both cases, not including the guts.

 

[bear]

Sweet little amp case there!

I'd change and increase the gauge of the ground wires on those caps by a WHOLE LOT. Like 10ga would suit me fine.

Also take your ground wires and somehow in that design create a very short "tab" off the center point to connect to, rather than spreading the connections, or having any connections elsewhere, including on the tabs of the caps... assuming you continue with this physical connection method, that's how I'd work it.

 

[Russellc]

Excellent Byrd, glad its working. As we discussed on the other forum, and despite what the naysayers say, your amp was not having an oscillation problem. Things would have smoked if you did. As I told you, Peter Daniels said up to 12 inches with the standard F-5 would be no problem. This wasnt directed to a turbo version, but the F-5 is also a very wide bandwidth amp. Easy fix, glad its working properly.

russellc

 

[SirByrd]

Excellent Byrd, glad its working. As we discussed on the other forum, and despite what the naysayers say, your amp was not having an oscillation problem. Things would have smoked if you did. As I told you, Peter Daniels said up to 12 inches with the standard F-5 would be no problem. This wasnt directed to a turbo version, but the F-5 is also a very wide bandwidth amp. Easy fix, glad its working properly.

russellc

Yes, I didn't think it was going to oscillate, since I built my first F5 this same way.