| Originally Posted by FallenAngel Thanks, but now that makes me wander. I simply put a resistor and an LED between V+ and V- which kinda closed the loop and got a completly stable (and very accurate) ground split when I was making the rail splitter. I'll check if that changed since attaching the amp, but if it hasn't then I'm pretty confused why I'm getting such an offset, guess I'll be looking for other problems. |
| Originally Posted by thedoctor i'm not exactly educated in Eagle, but here's a sketch. trying to learn how to use it to draw schemtics, but free time is running low.   |
| Originally Posted by Eokboy A schematic woot! I'll try drawing this back in TinyCAD. So this thing would work well with alkalines/rechargeables? I've been using BC327/BC337, no -25/-40 at the back. |
| Originally Posted by thedoctor try feeding it with 24V and you'll see what i'm talking about.
you're having DC offset problem with your unit? are you using input capacitors? if yes, then try bypassing them. or you could ground the Opamp input with a high value resistor. amb already mentioned about this. |
| Originally Posted by thedoctor i'm not exactly educated in Eagle, but here's a sketch. trying to learn how to use it to draw schemtics, but free time is running low. |
| Originally Posted by FallenAngel Hey guys, After building like 5 different Sijosae Class-AB amps, I'll finally try to build this one (and another modified version of it but that's later), and I've got a couple of quick questions. This version I don't see the power caps in the schematic, I'll be using something like a TREAD to power this thing and I usually put them power caps right after the rail splitter, but here I don't see that at all. Should I just put in a big cap across the V+/V- rails, but I see 2 caps and I'm not positive no how they're wired. From what I've always seen, the caps should be going between V+ to Ground and V- to Ground, is that the case here, and if yes, where on the ground is it going, I'm thinking Input Ground. |
| My Upcoming modification Since this amp uses a dual-opamp for the ground channel and rail splitter, If space is not an issue, wouldn't it be benefitial and more cost efficient to use a good opamp for the ground channel and a cheap one for the rail splitter or just use a TLE2426 with a few caps following it like the Pimeta power supply? Thanks in advance! |
| Originally Posted by cetoole Personally, I would just put ps caps from v+ to v-, though you could, and there are arguements for and against this, put caps from v+ to v- and also some from v+ to input gnd and v- to input gnd. Dont put any on the output gnd. |
| Originally Posted by cetoole Beneficial, maybe, probably. Cost effective, probably not. Dual opamps tend not to cost much more than single ones. I can see a few changes to that schematic that I am pretty sure would make a bigger difference than what you suggested. First, add resistors in series with the emitters of each of the input transistors in the buffer greater than or equal to the value of the resistors in series with the emitters of the output transistors (>=4.7r), for Class A-AB biasing, and second, replace the 3k biasing resistor for the input transistors of the buffer with a ccs, whether it be a CRD, lone jfet, jfet cascode, or something else. The following is an example of what I mean, though without any parts values. I just happened to have this made up and uploaded to my photobucket account for the Pimeta BUF634 replacement diamond buffer boards I was working on a while ago. To make it a bit easier, you could swap CRDs for the two 2N5484 jfets. It would also remove the need to match the jfets.
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