kevin gilmore Posted January 25, 2017 Report Share Posted January 25, 2017 (edited) probably close to final 2.45 x 2.17 inch Edited January 25, 2017 by kevin gilmore 3 Quote Link to comment Share on other sites More sharing options...
congo5 Posted January 25, 2017 Report Share Posted January 25, 2017 nice, Very nice! Quote Link to comment Share on other sites More sharing options...
sorenb Posted January 25, 2017 Report Share Posted January 25, 2017 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? Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted January 25, 2017 Report Share Posted January 25, 2017 (edited) 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, 2017 by kevin gilmore Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted January 26, 2017 Report Share Posted January 26, 2017 transistors are 2sc3324 and 2sa1312 Quote Link to comment Share on other sites More sharing options...
Pars Posted January 27, 2017 Report Share Posted January 27, 2017 BL or GR?Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted January 27, 2017 Report Share Posted January 27, 2017 highest hfe, make sure to match hfe and vbe Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted January 27, 2017 Report Share Posted January 27, 2017 (edited) deleted Edited January 27, 2017 by kevin gilmore Quote Link to comment Share on other sites More sharing options...
congo5 Posted January 28, 2017 Report Share Posted January 28, 2017 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 2 Quote Link to comment Share on other sites More sharing options...
Pars Posted January 28, 2017 Report Share Posted January 28, 2017 (edited) 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, 2017 by Pars Quote Link to comment Share on other sites More sharing options...
congo5 Posted January 28, 2017 Report Share Posted January 28, 2017 (edited) 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, 2017 by congo5 Quote Link to comment Share on other sites More sharing options...
cspirou Posted January 28, 2017 Report Share Posted January 28, 2017 What's the gain on the ubal -> bal boards? Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted January 28, 2017 Report Share Posted January 28, 2017 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 1 Quote Link to comment Share on other sites More sharing options...
cspirou Posted January 29, 2017 Report Share Posted January 29, 2017 For a preamp I have the following plan: input -> (ubal/bal) -> digi.attenuator -> diamond buffer -> output What value attenuation do I need to use? Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted January 29, 2017 Report Share Posted January 29, 2017 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 Quote Link to comment Share on other sites More sharing options...
sbelyo Posted February 3, 2017 Author Report Share Posted February 3, 2017 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: Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted February 3, 2017 Report Share Posted February 3, 2017 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 Quote Link to comment Share on other sites More sharing options...
sbelyo Posted February 3, 2017 Author Report Share Posted February 3, 2017 Got it... So it's ok to omit the attenuator then? Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted February 3, 2017 Report Share Posted February 3, 2017 sure as long as you don't mind the gain, or have a knob elsewhere (or a dac with a volume control etc) Quote Link to comment Share on other sites More sharing options...
sbelyo Posted February 3, 2017 Author Report Share Posted February 3, 2017 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? Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted February 3, 2017 Report Share Posted February 3, 2017 yes that is how it works Quote Link to comment Share on other sites More sharing options...
sbelyo Posted February 3, 2017 Author Report Share Posted February 3, 2017 much thanks... perhaps I will enable attenuation in the DAC when using this as part of a preamp Quote Link to comment Share on other sites More sharing options...
fat joey Posted February 4, 2017 Report Share Posted February 4, 2017 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? Quote Link to comment Share on other sites More sharing options...
recstar24 Posted February 4, 2017 Report Share Posted February 4, 2017 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. Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted February 4, 2017 Report Share Posted February 4, 2017 (edited) 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, 2017 by kevin gilmore Quote Link to comment Share on other sites More sharing options...
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