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Diabolical Artificer · 22nd Aug 2019, 10:28 am

The two big monoblocks I built get very hot after a while, I have a fan drawing air up through the PSU, this then goes into the amp chassis to cool things there, then through six holes round each OP valve. To reduce fan noise I put a 100r to slow the fan down, at low volume it can't be heard, but to cool the amp it needs to be on full whack.

So I thought of taking the OP after the OPT, into a buffer, a 10M and Opamp buffer, into a diode to rectify, into a "comparator", OP from this to a tranny to turn on a relay which will short out the dropping R on the fan, see att.

Anything I've missed? Andy.

22nd Aug 2019, 10:28 am	#1
Diabolical Artificer Dekatron Join Date: Jul 2009 Location: Sleaford, Lincs. UK. Posts: 7,657	Fan speed control by OP of amp. The two big monoblocks I built get very hot after a while, I have a fan drawing air up through the PSU, this then goes into the amp chassis to cool things there, then through six holes round each OP valve. To reduce fan noise I put a 100r to slow the fan down, at low volume it can't be heard, but to cool the amp it needs to be on full whack. So I thought of taking the OP after the OPT, into a buffer, a 10M and Opamp buffer, into a diode to rectify, into a "comparator", OP from this to a tranny to turn on a relay which will short out the dropping R on the fan, see att. Anything I've missed? Andy. Attached Thumbnails __________________ Curiosity hasn't killed this cat...so far.