Good practics is to put the bypass caps as close to the IC leads as is practical, and run short traces (or wires) to the IC pins.
I wasn't suggesting one bypass cap from V+ to ground and another from V- to ground... since you're using a single-sided supply and V- is DC ground, that would be redundant (as you have noted).
--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!
1uF
that would work
NT
--- Amen to that!
The beauty parts are that it doesn't need to be regulated, it only needs to be smooth enough so that its ripples don't bump into the output's low peaks, and it gets rid of all those damned coupling caps and their frequency response killing reactances.
I was going to suggest that, since the mixer is going to be external to the amp, he use a couple of wall-warts to get the dual supplies, but I like your solution a lot better. :-)
-- JF
Enough to suggest a nice circuit? ;-)
Thanks, Dave
I'm learnin'! Thanks for the explanation. I'll use standard aluminum 'lytics here, connected as noted.
Dave C.
Hint: Don't use the chassis ground symbol as a "Vref" symbol. It's confusing and someone along the line might get hurt. Grounds should be.
confusing
Yeah, I wasn't sure about that. How should I have indicated 2 separate grounds?
Thanks.
Distortion performance might be better if you run the amps in inverting mode. If you run the audio into the non-inverting inputs, the inverting input follows and the amp has to operate throughout it's common-mode range. If you use the amps in inverting mode, both the + and - inputs will stay very close to ground.
Isaac
??
What is wrong with using an op-amp to "amplify" DC? Surely they are "meant" to do that.
Isaac
I think he means that better audio results can be achieved by providing true dual-voltage supplies and eliminating all coupling caps.
The "DC amplifier" is a fine design, but will result in inferior audio performance due to the caps.
Now, if someone would volunteer such a negative voltage generator circuit... ;-)
Thanks.
It's not ground. It's Vcc/2. I generally call it Vref, or some such thing.
Exactly. Much easier than all these halved supplies, coupling caps and multiple grounds.
d
So, how -- exactly -- would you create that negative voltage?
Dave
On Thu, 10 Nov 2011 00:51:03 -0800, DaveC wrote:
--- Version 4 SHEET 1 964 748 WIRE -32 80 -176 80 WIRE 960 80 192 80 WIRE -32 144 -80 144 WIRE 256 144 192 144 WIRE -32 208 -80 208 WIRE 320 208 192 208 WIRE 384 208 320 208 WIRE 512 208 464 208 WIRE 624 208 576 208 WIRE 672 208 624 208 WIRE 784 208 736 208 WIRE 880 208 784 208 WIRE 320 240 320 208 WIRE 224 272 192 272 WIRE 880 288 880 208 WIRE -176 336 -176 80 WIRE 224 336 224 272 WIRE 224 336 -176 336 WIRE 624 352 624 208 WIRE 784 352 784 208 WIRE -80 368 -80 208 WIRE 256 368 256 144 WIRE 256 368 -80 368 WIRE 320 368 320 320 WIRE 320 368 256 368 WIRE -176 384 -176 336 WIRE 320 400 320 368 WIRE -176 512 -176 464 WIRE 320 512 320 464 WIRE 320 512 -176 512 WIRE 624 512 624 416 WIRE 624 512 320 512 WIRE 784 512 784 416 WIRE 784 512 624 512 WIRE 880 512 880 368 WIRE 880 512 784 512 WIRE 960 512 960 80 WIRE 960 512 880 512 WIRE -176 560 -176 512 FLAG -176 560 0 SYMBOL Misc\\NE555 80 176 M0 SYMATTR InstName U1 SYMBOL voltage -176 368 M0 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V1 SYMATTR Value 16 SYMBOL res 896 272 M0 SYMATTR InstName R3 SYMATTR Value 1000 SYMBOL cap 336 400 M0 SYMATTR InstName C1 SYMATTR Value 1n SYMBOL diode 736 224 M270 WINDOW 0 32 32 VTop 2 WINDOW 3 0 32 VBottom 2 SYMATTR InstName D2 SYMATTR Value 1N4148 SYMBOL diode 640 352 M0 SYMATTR InstName D3 SYMATTR Value 1N4148 SYMBOL polcap 800 352 M0 SYMATTR InstName C4 SYMATTR Value 1µ SYMBOL polcap 512 192 M90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C2 SYMATTR Value 1µ SYMBOL res 304 224 R0 SYMATTR InstName R1 SYMATTR Value 10k SYMBOL res 480 192 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R2 SYMATTR Value 100 TEXT -40 536 Right 2 !.tran .01 startup uic
-- JF
-- Sure, a 555 charge pump. Got LTspice yet?
On Thu, 10 Nov 2011 00:51:03 -0800, DaveC wrote:
--- Here's the whole thing; DC coupled mixer with a charge pump for a negative supply:
Version 4 SHEET 1 1676 1124 WIRE -32 -528 -64 -528 WIRE 80 -528 48 -528 WIRE -208 -432 -528 -432 WIRE -96 -432 -128 -432 WIRE -64 -432 -64 -528 WIRE -64 -432 -96 -432 WIRE -32 -432 -64 -432 WIRE 80 -416 80 -528 WIRE 80 -416 32 -416 WIRE 112 -416 80 -416 WIRE 320 -416 192 -416 WIRE 464 -416 320 -416 WIRE -32 -400 -64 -400 WIRE 320 -384 320 -416 WIRE 224 -368 176 -368 WIRE -64 -352 -64 -400 WIRE -208 -336 -432 -336 WIRE -96 -336 -96 -432 WIRE -96 -336 -128 -336 WIRE 128 -336 128 -368 WIRE 320 -272 320 -304 WIRE -528 -240 -528 -432 WIRE -416 -240 -528 -240 WIRE -64 -240 -336 -240 WIRE -32 -240 -64 -240 WIRE 80 -240 48 -240 WIRE -432 -192 -432 -336 WIRE -352 -192 -432 -192 WIRE -64 -192 -64 -240 WIRE -64 -192 -272 -192 WIRE -272 -144 -336 -144 WIRE -64 -144 -64 -192 WIRE -64 -144 -192 -144 WIRE -176 -96 -240 -96 WIRE -64 -96 -64 -144 WIRE -64 -96 -96 -96 WIRE -32 -96 -64 -96 WIRE 80 -80 80 -240 WIRE 80 -80 32 -80 WIRE 112 -80 80 -80 WIRE 320 -80 192 -80 WIRE 464 -80 320 -80 WIRE -32 -64 -64 -64 WIRE 320 -48 320 -80 WIRE 224 -32 224 -368 WIRE 224 -32 176 -32 WIRE -64 -16 -64 -64 WIRE 128 0 128 -32 WIRE 320 64 320 32 WIRE -32 96 -64 96 WIRE 80 96 48 96 WIRE -336 192 -336 -144 WIRE -208 192 -336 192 WIRE -96 192 -128 192 WIRE -64 192 -64 96 WIRE -64 192 -96 192 WIRE -32 192 -64 192 WIRE 80 208 80 96 WIRE 80 208 32 208 WIRE 96 208 80 208 WIRE 320 208 176 208 WIRE 464 208 320 208 WIRE -32 224 -64 224 WIRE 320 240 320 208 WIRE 224 256 224 -32 WIRE 224 256 160 256 WIRE -64 272 -64 224 WIRE -240 288 -240 -96 WIRE -208 288 -240 288 WIRE -96 288 -96 192 WIRE -96 288 -128 288 WIRE 112 288 112 256 WIRE 320 352 320 320 WIRE 48 368 -64 368 WIRE 224 368 224 256 WIRE 224 368 128 368 WIRE 224 400 224 368 WIRE 224 496 224 464 WIRE -80 576 -112 576 WIRE -64 576 -64 368 WIRE -64 576 -80 576 WIRE 16 576 -64 576 WIRE 336 576 240 576 WIRE 304 640 240 640 WIRE 16 704 -32 704 WIRE 384 704 240 704 WIRE 464 704 384 704 WIRE 560 704 544 704 WIRE 656 704 624 704 WIRE 672 704 656 704 WIRE 752 704 736 704 WIRE 768 704 752 704 WIRE 384 736 384 704 WIRE 272 768 240 768 WIRE -80 832 -80 576 WIRE 272 832 272 768 WIRE 272 832 -80 832 WIRE 656 848 656 704 WIRE 752 848 752 704 WIRE -528 864 -528 -240 WIRE -432 864 -432 -192 WIRE -336 864 -336 192 WIRE -240 864 -240 288 WIRE -80 864 -80 832 WIRE -32 864 -32 704 WIRE 304 864 304 640 WIRE 304 864 -32 864 WIRE 384 864 384 816 WIRE 384 864 304 864 WIRE 384 896 384 864 WIRE -528 1008 -528 944 WIRE -432 1008 -432 944 WIRE -432 1008 -528 1008 WIRE -336 1008 -336 944 WIRE -336 1008 -432 1008 WIRE -240 1008 -240 944 WIRE -240 1008 -336 1008 WIRE -80 1008 -80 944 WIRE -80 1008 -240 1008 WIRE 336 1008 336 576 WIRE 336 1008 -80 1008 WIRE 384 1008 384 960 WIRE 384 1008 336 1008 WIRE 656 1008 656 912 WIRE 656 1008 384 1008 WIRE 752 1008 752 912 WIRE 752 1008 656 1008 WIRE -528 1104 -528 1008 FLAG -64 272 0 FLAG 0 -448 +16 FLAG 0 -384 -10 FLAG -64 -352 0 FLAG -528 1104 0 FLAG -64 -16 0 FLAG 464 -416 LA+LB FLAG 464 -80 LA+LB+RA+RB FLAG 464 208 RA+RB FLAG 0 -112 +16 FLAG 0 176 +16 FLAG 0 -48 -10 FLAG 0 240 -10 FLAG -112 576 +16 FLAG 768 704 -10 FLAG 128 -336 0 FLAG 128 0 0 FLAG 112 288 0 FLAG 224 496 0 FLAG 320 -272 0 FLAG 320 64 0 FLAG 320 352 0 SYMBOL Opamps\\LT1007 0 144 R0 SYMATTR InstName U1 SYMBOL voltage -240 848 R0 WINDOW 3 24 96 Invisible 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR Value SINE(0 1 1000) SYMATTR InstName RB SYMBOL res -112 176 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R1 SYMATTR Value 10k SYMBOL res -112 272 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R2 SYMATTR Value 10k SYMBOL res 64 80 R90 WINDOW 0 -35 58 VBottom 2 WINDOW 3 -35 60 VTop 2 SYMATTR InstName R3 SYMATTR Value 10k SYMBOL Opamps\\LT1007 0 -480 R0 SYMATTR InstName U2 SYMBOL res -112 -448 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R4 SYMATTR Value 10k SYMBOL res -112 -352 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R5 SYMATTR Value 10k SYMBOL res 64 -544 R90 WINDOW 0 -38 58 VBottom 2 WINDOW 3 -33 59 VTop 2 SYMATTR InstName R6 SYMATTR Value 10k SYMBOL res -80 -112 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R7 SYMATTR Value 10k SYMBOL res -176 -160 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R8 SYMATTR Value 10k SYMBOL res -256 -208 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R9 SYMATTR Value 10k SYMBOL res -320 -256 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R10 SYMATTR Value 10k SYMBOL Opamps\\LT1007 0 -144 R0 SYMATTR InstName U3 SYMBOL res 64 -256 R90 WINDOW 0 -37 62 VBottom 2 WINDOW 3 -37 60 VTop 2 SYMATTR InstName R12 SYMATTR Value 6.2k SYMBOL voltage -336 848 R0 WINDOW 3 24 96 Invisible 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR Value SINE(0 1 1700) SYMATTR InstName RA SYMBOL voltage -432 848 R0 WINDOW 3 24 96 Invisible 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR Value SINE(0 1 2300) SYMATTR InstName LB SYMBOL voltage -528 848 R0 WINDOW 3 24 96 Invisible 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR Value SINE(0 1 4260) SYMATTR InstName LA SYMBOL Misc\\NE555 128 672 M0 SYMATTR InstName U4 SYMBOL voltage -80 848 M0 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V3 SYMATTR Value 16 SYMBOL cap 400 896 M0 WINDOW 0 -19 1 Left 2 WINDOW 3 -21 57 Left 2 SYMATTR InstName C1 SYMATTR Value 1n SYMBOL diode 736 720 M270 WINDOW 0 32 32 VTop 2 WINDOW 3 0 32 VBottom 2 SYMATTR InstName D1 SYMATTR Value 1N4148 SYMBOL diode 672 848 M0 SYMATTR InstName D2 SYMATTR Value 1N4148 SYMBOL polcap 768 848 M0 SYMATTR InstName C2 SYMATTR Value 1µ SYMBOL polcap 560 688 M90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C3 SYMATTR Value 1µ SYMBOL res 368 720 R0 SYMATTR InstName R13 SYMATTR Value 10k SYMBOL res 560 688 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R14 SYMATTR Value 100 SYMBOL sw 96 -416 R270 WINDOW 0 32 15 Left 2 WINDOW 3 32 44 Left 2 SYMATTR InstName S2 SYMBOL sw 96 -80 R270 WINDOW 0 32 15 Left 2 WINDOW 3 32 44 Left 2 SYMATTR InstName S1 SYMBOL sw 80 208 R270 WINDOW 0 32 15 Left 2 WINDOW 3 32 44 Left 2 SYMATTR InstName S3 SYMBOL res 144 352 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R11 SYMATTR Value 10k SYMBOL cap 208 400 R0 SYMATTR InstName C5 SYMATTR Value 100n SYMBOL res 304 -400 R0 SYMATTR InstName R15 SYMATTR Value 1000 SYMBOL res 304 -64 R0 SYMATTR InstName R16 SYMATTR Value 1000 SYMBOL res 304 224 R0 SYMATTR InstName R17 SYMATTR Value 1000 TEXT -296 1040 Right 2 !.tran .01 startup uic TEXT -488 1080 Left 2 !.model SW SW(Ron=1 Roff=10Meg Vt= 8 Vh=0)
-- JF
-- Of course, but if an AC input and output is desired and no negative supply is available, the input and output must be capacitively coupled, which is, at best, kind of nasty.
Thanks John. Nice design.
What part is used for SW1-3? Purpose? If these are "anti-thump" turn-on suppression switches, I think the main amp is similarly turn-on delayed. Of course it's important to know the timing of these to avoid any window through which the sub's cone could launch (or lunch?)...
Thanks, Dave
John, what's the reason behind choosing 6.2K for the feedback R on U3 (sub op amp)? And if that is to be a pot (the original idea), is 10K appropriate?
There should be some kind of sub volume control...
Thanks, Dave
C2, C3 are polarized, so I presume electrolytic?
What type should C1 be?
Thanks.
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.