No. Barely warm - 6A^2 x 0.5R is 18w for a 10lb chunk of steel and copper is nothing.
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Interesting. 6A ^2 * 0.5 ohms = 18 watts. I would expect the copper winding to get warm and eventually transfer that to the core. Can you aim your IR thermometer at the copper primary winding?
It would probably take at least 30min to reach full temp. I’ll take a reading when I run it again later.
Copy that. I am behind you many days. Hope to have a start by the end of the week.
After 1hr at 6A bias current but no music playing, MOT primary was 42C and steel core 30C.
After 30 min of full power 40w sine wave testing, MOT primary was 70C and steel core was 55C.
Sine wave testing definitely heats the MOT vs DC only.
I added a SSR soft start circuit to the LuFo today. Upon power up, the trafo is fed AC mains through three NTCs in series (about 24ohms) for 2 seconds, then a pair of back to back low RDson MOSFETs controlled by an optoisolator is then switched on to bypass the NTCs.
It’s much nicer than burning off all the current as heat through a full time NTC as a soft start.
I connected my 10F/RS225 TLs in parallel to the mono speaker outs (4ohms nominal combined) to get a better sense of the sound from two speakers. It’s driving 4ohms no problem.
It’s much nicer than burning off all the current as heat through a full time NTC as a soft start.
I connected my 10F/RS225 TLs in parallel to the mono speaker outs (4ohms nominal combined) to get a better sense of the sound from two speakers. It’s driving 4ohms no problem.
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My order for some OPA454’s came in. We are going to design a custom M2X format daughterboard that will go onto the main amp PCB to provide high swinging output - up to 50mA and +/-50v. The 454 has 0.0008% THD spec so should be fine for the 0.01% nominal THD of the LuFo.
Please let us know if your ACP+ or M2x/Yarra is ready for this application or it is necessary to modify it 🙂
The Yarra with Melbourne daughterboard and the proper +/-30v transformer PSU can drive this amp without any problem.
Sorry, I intended your ACP+ daughterboard For M2x
Please let us know if your ACP+ or M2x/Yarra is ready for this application or it is necessary to modify it 🙂