[comabereni]

I was experiencing a low hum in my Millett amp until tonight. Never noticed it in headphones, but it was audible at higher volumes when using the Millett as pre-amp with my loudspeakers. Well, problem solved with the arrival of a linear, regulated 28VDC PSU. Yes, it's [size=medium]HUGE[/size], but it wasn't that much more (used, like new, Ebay) than the 24V wall wart recommended for this amplifier. I bet I can hook up a few more amps to this thing, (and I plan to...)

Just thought I'd pass the word to try and avoid the 24VDC, 400mA (Model #DV-2440, shown in foreground) power supply recommended for this amp if possible due to the pre-amp hum problem. I doubt the amp would sound much (if any) better running off battery power. It's really quiet now and got an extra 4V to boot.

-coma

 

[Wodgy]

As a bonus, you get more headroom with less distortion on headphones when you use a 28V power supply with this amp. You should remember to readjust the bias to 14V at minimum and experiment with 17-18V.

 

[comabereni]

Quote:

Originally Posted by Wodgy As a bonus, you get more headroom with less distortion on headphones when you use a 28V power supply with this amp. You should remember to readjust the bias to 14V at minimum and experiment with 17-18V.

I think Voodoochile already set the bias at around 18V (I bought this from him a few months ago), but I need to check it. I've got a different set of tubes to try out anyway...

-coma

P.S. For aesthetics reasons, I was really against big, ugly gray PSU's when I first arrived here on these forums a few months ago, but I've experienced a readjustment in my thinking. And they won't bother me at all once I've rack-mounted them behind panels with new on/off switches.

 

[Wodgy]

Quote:

Originally Posted by comabereni I think Voodoochile already set the bias at around 18V (I bought this from him a few months ago), but I need to check it. I've got a different set of tubes to try out anyway...

That's what I use too, but you'll probably need to reset the bias to 18V since you've increased the power supply voltage.

 

[comabereni]

Quote:

Originally Posted by Wodgy That's what I use too, but you'll probably need to reset the bias to 18V since you've increased the power supply voltage.

Good point--I'll take care of that soon. I sold my expensive Fluke DMM a couple years ago thinking I'd never find a use for it again, then I started hanging around this place.

BTW, I listened to this amp/psu combo for several hours last night and this morning and it does sound a notch better, on top of eliminating the hum. The PSU emits a barely audible hum of its own (audible from outside the case, not through speakers or headphones), but it'll be behind glass pretty soon.