I have been building a MooseFET preamp for over a year. Before running things need to be set up.
I am confused about using a voltmeter. The manual states "Upon powering the unit, adjust P1 for 24.00V on the B+ rail (the power side leads of R104 or R204 make a good test point for this)."
Where do I put the negative for the voltmeter?
Also same here "Once the B+ is confirmed, with an accurate voltmeter, check the drain voltage (the drain side leads of R104 or R204 make a good test point for this. See image below). While checking the drain voltage on Q101"
I have tried it in my system and something is wrong. Sound is only just audible at full volume with no lower frequencies. Also a loud buzzing that isn't affected by volume.
I am confused about using a voltmeter. The manual states "Upon powering the unit, adjust P1 for 24.00V on the B+ rail (the power side leads of R104 or R204 make a good test point for this)."
Where do I put the negative for the voltmeter?
Also same here "Once the B+ is confirmed, with an accurate voltmeter, check the drain voltage (the drain side leads of R104 or R204 make a good test point for this. See image below). While checking the drain voltage on Q101"
I have tried it in my system and something is wrong. Sound is only just audible at full volume with no lower frequencies. Also a loud buzzing that isn't affected by volume.
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Put the negative lead on the ground terminal . Check you have put the correct component value in its proper space .
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Its stil not running. Been advised the mosphets may be dud and I have been to busy to sort out.
They don't sell these anymore due to too many problems like this.
I have since made a mosphet phono preamp (boozehound labs) and was very happy it worked first time and sounds fantastic.
I know that mosfets can have varying turn on voltages - is that the kind of problem that you're talking about? These are usually just sold as pcbs right? So you have to source the parts yourself?
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Much better schematic at DIY Audio Projects Forum.
Did you get as far as measuring for +14.8V at the point indicated?
It is possible the 4.48V-5.6V bias trim is not wide enough for "all" things sold as IRF*10. If you post the voltages you observe, we may suggest alternate bias resistors to dial it in.
Did you get as far as measuring for +14.8V at the point indicated?
It is possible the 4.48V-5.6V bias trim is not wide enough for "all" things sold as IRF*10. If you post the voltages you observe, we may suggest alternate bias resistors to dial it in.
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I am sure I did, it seems so long ago I can't remember details. I do have to replace a zener diode as I thought maybe I put power cap in wrong way so changed it and instantly one of them blew. So i had put cap the correct way in the first place.
If i get the chance I will get it going the weekend to check what values I get.
