January 25, 20179 yr probably close to final 2.45 x 2.17 inch Edited January 25, 20179 yr by kevin gilmore
January 25, 20179 yr 9 hours ago, kevin gilmore said: lm49830 is a chip amp do you mean opa1632 and its clones, all of which require huge amounts of feedback and have all sorts of common mode dc issues didn't you use lm49830 for the blackhole buffer?
January 25, 20179 yr that was not a buffer. that was a 60 watt + power amp done with semisouth as output devices.. It was pretty nice for a small chip amp. Edited January 25, 20179 yr by kevin gilmore
January 28, 20179 yr Trying to figure out a way to make 6 boards manageable, would like some sockets but don't have any yet> sockets for .030 pins with .100" spacing? So the buffers clamp to 18ga wire with normal connectors to take apart you have to work your way in. one power connection stereo in balanced and buffered out, pot could go between the white 3 pin connectors
January 28, 20179 yr Maybe some of these Amp receptacles? For 0.0252" pins 649-75915-304LF That one is a 4 position. Are you trying to find a connector type to connect the buffers to the ubal->bal boards? I actually think that Kevin should just put the buffers right on the ubal boards. They wouldn't add that much real estate, and if you didn't want to use them, you could just jumper them. The Phoenix connectors seem to add a bit of real estate on small boards such as these though Edited January 28, 20179 yr by Pars
January 28, 20179 yr 10 minutes ago, Pars said: I actually think that Kevin should just put the buffers right on the ubal boards. they are on the smd version, plug in through hole solder pins and yes jumper them out, use em' or try other buffers, excellent! thanks those connectors will work. if not here somewhere Edited January 28, 20179 yr by congo5
January 28, 20179 yr unbalanced to unbalanced, gain of 1 unbalanced to balanced, gain of 2 etc you can adjust the gain by changing the 1300 ohm resistors, or the emitter resistors up to 10x is possible with no increase in distortion these days, I don't think there is any reason to add much gain
January 29, 20179 yr For a preamp I have the following plan: input -> (ubal/bal) -> digi.attenuator -> diamond buffer -> output What value attenuation do I need to use?
January 29, 20179 yr the way the board is layed out currently its really input -> attenuator -> ubal/bal -> diamond buffer because there is only one set of servo's and the attenuator is best at something like 10K
February 3, 20179 yr Author On 1/29/2017 at 3:18 PM, kevin gilmore said: the way the board is layed out currently its really input -> attenuator -> ubal/bal -> diamond buffer because there is only one set of servo's and the attenuator is best at something like 10K If I wanted to make a preamp with these boards can I omit the attenuator and wire it like this? For example:
February 3, 20179 yr for the input switch you want to ground the - input for SE inputs don't need a switch on the output because you can do balanced and unbalanced at the same time
February 3, 20179 yr sure as long as you don't mind the gain, or have a knob elsewhere (or a dac with a volume control etc)
February 3, 20179 yr Author understood... My DAC does have a digital volume control but I disable it. So if this board increases the balanced gain and I feed it to an amp it's multiplied again by whatever gain the amp is at correct?
February 3, 20179 yr Author much thanks... perhaps I will enable attenuation in the DAC when using this as part of a preamp
February 4, 20179 yr On 2017/1/30 at 4:18 AM, kevin gilmore said: the way the board is layed out currently its really input -> attenuator -> ubal/bal -> diamond buffer because there is only one set of servo's and the attenuator is best at something like 10K is this input + output board + attenuator also the same as here? Or put the attenuator in between the two boards? https://www.head-case.org/forums/topic/12024-and-now-for-something-completely-different-part-3/?page=6#comment-724017 BTW, about these output boards, the orginal one and the newer one, could we wire them to output SE signals?
February 4, 20179 yr Excuse my ignorance, but isn't this a good scenario where an opamp actually performs well? At minimum it's a more cost effective option.
February 4, 20179 yr so I did something like that with an opa1632, everyone over at amb's picked on me, and in fact it sounded like shit. Then Ti released exactly the same thing. Still sounds like shit. Lots and lots of feedback is why. This discrete thing is pure class A and current sources, and no feedback. except for dc servo sounds so much better congo5 is testing the surface mount stuff, currently the output buffer blows up due to power over 15v, so will trim the current a bit, the surface mount transistors can only take 150mw. size vs power. It will run just fine on 15v anyway Edited February 4, 20179 yr by kevin gilmore
Please sign in to comment
You will be able to leave a comment after signing in
Sign In Now