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Messages - purpletheory

#1
Amplifier Discussion / Re: almost....
November 18, 2006, 10:22:53 AM
Oops sorry, here's the PS: http://sound.westhost.com/project04.htm
and I built two of these: http://www.generalguitargadgets.com/pdf/ggg_lm3886_amp.pdf
The lamp is 120v connected directly to the switch along with the mains power.

I kinda think that it's not stored charge from the caps because the lamp only lights up when the power cord is connected and disappears as soon as it is disconnected.

thanks,
matt
#2
Amplifier Discussion / almost....
November 16, 2006, 09:12:11 PM
Hey guys,

I almost have my amp done, though i've run into something wierd. I wired everything up, but when I flipped on the switch the lamp came on for a second and burnt out. I thought maybe the lamp was defective, so I replaced it, now it powers on fine, it's just that I noticed that when the power cable is connected and the switch is turned off, the lamp lights up ever so slightly. I tested it and found out that 11v are mysteriously powering it, and I can't for the life of me figure out where it's coming from. Don't know if the part about the lamp burning out is of any significance, just thought i would mention it just in case. Any ideas?
#3
Preamps and Effects / tl071 preamp question
October 04, 2006, 02:02:20 PM
Hey guys,
I ended up building the tl071 preamp suggested in the forum(http://www.diyguitarist.com/PDF_Files/OpampGuitarPreamp.pdf)

Works great, although it is a bit dark for my tastes. I was wondering how could I brighten it up a bit, or is the idea of the circuit to color the sound by using fx in front of it? Also a side note; I didn't have any tl071's on hand when I built it so it currently has an lm741, and i read somewhere else that tl071 is generally brighter than other op amps, don't know how much it will affect the sound, I should have some by the end of the week to try out.

Thanks,
matt
#4
Amplifier Discussion / Chassis too small
September 30, 2006, 02:56:30 PM
Hi Guys,

I finally found some time to work on my amp again, now I'm just trying to get everything to fit inside the chassis. I was wondering if it would be a problem to mount the transformer on the outside of the chassis or will it be more prone to interferance, hum, whatever.

Thanks,
Matt
#5
Amplifier Discussion / Re: dumb transformer question
September 12, 2006, 12:51:17 AM
cool, thx for the help!

matt
#6
Amplifier Discussion / dumb transformer question
September 11, 2006, 11:32:06 PM
hey guys!

ok, so i'm trying to build a stereo lm3886 guitar amp, as for the transformer i bought this:
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=122-615
got it in the mail today, but i had a question about it  (i couldn't see anything about it in the formum, so i appologize if this question has already been addressed):
the transformer appears to have 4 mains and 4 secondaries, which is new to me. just thought i would ask you guys before i ruin something. i plan on building a ps like this:
http://sound.westhost.com/project04.htm
so here go the embarrasing questions:

do i connect both sets of mains? why 2 sets of mains?

i'm assuming that the "0v" secondaries connect together, is that right?

thx in advance for any help and thx joecool for inviting me to the forum!

matt