tropicalrips 0 Report post Posted November 21, 2004 new layout looks better more neat Share this post Link to post Share on other sites
bpribadi 0 Report post Posted November 22, 2004 Yeah, looks neater How do you use the OPA2134 for the ground channel without any resistor? Using single channel or dual? Did you put the input signal ground after the output of the ground channel, or still at the input? Let's compare the sounds of the 3 variants Share this post Link to post Share on other sites
jasonhanjk 0 Report post Posted November 22, 2004 Very nice! Mind disclosing how much it costs to prototype a single PCB like that? And for 10 pcs? Where do you go for your prototyping? $46 USD for 6. http://www.olimex.com/pcb/ Share this post Link to post Share on other sites
jasonhanjk 0 Report post Posted November 22, 2004 Yeah, looks neater How do you use the OPA2134 for the ground channel without any resistor? Using single channel or dual? Did you put the input signal ground after the output of the ground channel, or still at the input? Let's compare the sounds of the 3 variants Both input and output are at 0V output. Sometimes the 2 opamp at opa2134AP is not accurate enough so it caused it to oscillate. Then I had to cut the trace up and add a 10 ohm resistor underneath. If you use OPA2132BP (very X), should not be a problem. Share this post Link to post Share on other sites
bpribadi 0 Report post Posted November 25, 2004 Looks better on the IG and OG But I hope you give up using OPA2134 for the ground channel It's kind of defeating the purpose of using A47 for the Right and Left Channel. Look, with A47 on the Left and Right Channel, in theory each can supply 80 mA current if using OPA2134 (60mA with OPA2228). So an ideal ground should be able to cater for 160 mA. But with the circuit above, max only 80 mA. And also connecting 2 output without any resistor is just not right (as you said might cause oscillation). In most cases, only 1 op-amp will work at a time. So my suggestion is, don't use the A47 circuit for the ground channel, and use a simple unity gain single op-amp config with high current output op-amp such as LM6171 (the cheapest option, 135 mA), or OPA551 for higher output current (200 mA), but OPA551 cost around SGD 7 - 8 each (Will be cheaper if you buy in bulk). My 2 Cents Share this post Link to post Share on other sites
jasonhanjk 0 Report post Posted November 25, 2004 Bram, thanks for your wonderful input. I find that with my current design, I can fit in an LM6171 by bending a few pins. The ground channel can be use with single opamp or dual opamp design. Here's how: Cut away pin 1, 5 and 8. Bend pin7 to pin8 location. Bend pin6 to pin7 location. Walla!!! Share this post Link to post Share on other sites
bpribadi 0 Report post Posted November 25, 2004 (edited) You're welcome ! Here's how: Cut away pin 1, 5 and 8. Bend pin7 to pin8 location. Bend pin6 to pin7 location. That's another way. What I did, I didn't bend any pin, I cut one pcb track and short pin 7 & 8: http://www.sgheadphones.net/index.php?showtopic=2400&st=180 Edited November 25, 2004 by bpribadi Share this post Link to post Share on other sites
jasonhanjk 0 Report post Posted November 25, 2004 The new PCB revision you can't cut the traces anymore. I think this will be the final design as you can play with multiple configuration. Share this post Link to post Share on other sites
knuxed 0 Report post Posted November 25, 2004 Can i Know how can i purchase this amp,this is because I will be down in Singapore and want to get this amp for myself Share this post Link to post Share on other sites
sigma 0 Report post Posted November 26, 2004 Can i Know how can i purchase this amp,this is because I will be down in Singapore and want to get this amp for myself It isn't ready yet and it's not an amp, but rather a kit with all the parts that you need to assemble the amp. You'll still have to assemble it yourself. Share this post Link to post Share on other sites
knuxed 0 Report post Posted November 27, 2004 Regarding to that question,can I know where to purchase it,I wouldnt mind assembling it myself Share this post Link to post Share on other sites
av98m 0 Report post Posted November 27, 2004 (edited) It isn't ready yet see quote If you cannot wait, Headsave(www.headsave.com) from Canada sells excellent portable amps. I highly recommend him. Of course, his amps will cost you slightly more. Edited November 27, 2004 by av98m Share this post Link to post Share on other sites
jasonhanjk 0 Report post Posted December 6, 2004 Ok, after few test no problem. Will order production this week. Is tropical around? Share this post Link to post Share on other sites
tropicalrips 0 Report post Posted December 6, 2004 (edited) yes jason sorry didn't see your sms today no work today, playing online game whole afternoon i don't quite understand the new board...if the iG & oG is already connected together, what is the third op-amp for? can the new board work with just 2 op-amps? left & right channel op-amps only, the first version can't work this way Edited December 6, 2004 by tropicalrips Share this post Link to post Share on other sites
jasonhanjk 0 Report post Posted December 6, 2004 I see... I will do the same if I were you playin game... The voltage devide uses 2 resistor in series. If I take the opamp away the voltage will drift to one side. Share this post Link to post Share on other sites
