jasonhanjk 0 Report post Posted July 15, 2004 Wow, Mackie really know how to explain things... Another "bad" thing having a cap in the signal is it will slow down the 20Hz to 100Hz frequency by 10 degrees. Meaning sound is distort a bit and the tempo maybe slow. Share this post Link to post Share on other sites
Q00 0 Report post Posted July 15, 2004 cool...thanks for the info Mackie... So a cap would be a 'bad thing' in the signal path? Does the current design have a cap then? Share this post Link to post Share on other sites
mukegile 0 Report post Posted July 16, 2004 slow down the 20Hz to 100Hz phase shift ? Share this post Link to post Share on other sites
digi01 0 Report post Posted July 16, 2004 Hi jason,have you plan to offer a all parts kit?including the case? if thus,I agree with Mackie,the budget $30-40 is realistic Share this post Link to post Share on other sites
jasonhanjk 0 Report post Posted July 18, 2004 Ya. $40 will be a max out version. I had done a calculation using cheap opamp and without pot and casing will be less than $25. Will update first page. Currently still creating the alps pot symbol in eagle as it is not available. Find some PCB manufacture and will contact them next week. Share this post Link to post Share on other sites
tropicalrips 0 Report post Posted July 20, 2004 (edited) got the amp today from jason initial test is very promissing, drives Grado without any problem, design a layout also seems to be very stable, don't hear any noise even with an expose board i hav tried a few op-amps for the left/right channels changing out the opa2134 that jason left on the amp, AD823 , LM881 , opa2604 & opa2228. the LM881 was unusable, it has a lot of distortion, and one of the chip heats up, i'm guessing the speed of this op-amp thats causing this. the AD823 sounds good, with very good drive, but i feels its a little too full-bodied, lossing some details, this chip still sounds better with EL2001 or BUF634 as buffer my fav op-amp with this board is the opa2228, this was very surprising to me as the chip didn't sound good on a Cmoy or A47. The opa2228 sounds the most balanced of the 3 op-amps i tried, with good details and mid-range the opa2604 sounded weak, i think this chip needs a high voltage to sound good, still trying it out Edited July 20, 2004 by tropicalrips Share this post Link to post Share on other sites
Q00 0 Report post Posted July 20, 2004 Ooh...you guys are at the final few development stages... i cant wait! Share this post Link to post Share on other sites
bpribadi 0 Report post Posted July 21, 2004 my fav op-amp with this board is the opa2228, this was very surprising to me as the chip didn't sound good on a Cmoy or A47. The opa2228 sounds the most balanced of the 3 op-amps i tried, with good details and mid-range Hi Tropicalrips, I thought you guys built an A47? So what circuit is good for the OPA2228? I would like to try one, let us know when you guys ready with the 'production model' Share this post Link to post Share on other sites
digi01 0 Report post Posted July 21, 2004 tropicalrips,good PCB layout.those components looks balance and neat.I think what you need is a sexy case now What power supply do you use for? and have you do the high frequency compensate in feed back loops? congratulations Share this post Link to post Share on other sites
Mackie 0 Report post Posted July 21, 2004 I can almost hear it as interest in this project flares up following tropicalrip's post. Share this post Link to post Share on other sites
huangyong 0 Report post Posted July 21, 2004 (edited) NICE work.. tropicalrip.... uses audio grade components too... blackgate and WIMA. am i right?? would you guys condsider using opa627 for this amp? though it's expensive ( $40+ in farnell ), but we have a lobang king here, can get it for around half price. maybe we can use opa627-->opa227/228. whahahahah...it will be great then... mini high-end.. Edited July 21, 2004 by huangyong Share this post Link to post Share on other sites
mukegile 0 Report post Posted July 21, 2004 maybe we can use opa627--> huangyong.....why dun u pass it to tropical for some test and comparison ? Share this post Link to post Share on other sites
huangyong 0 Report post Posted July 21, 2004 sure.. i just get my opa627BP yesterday. Share this post Link to post Share on other sites
huangyong 0 Report post Posted July 21, 2004 tropicalrips , you got PM. Share this post Link to post Share on other sites
bpribadi 0 Report post Posted July 21, 2004 (edited) Huangyong wrote: ...though it's expensive ( $40+ in farnell ), but we have a lobang king here, can get it for around half price. Hi Huangyong, Where? where? I want a pair to Does your 'lobang' can get the OPA637 as well? If you don't mind, please let us know where to buy OPA627/637 with half of Farnell price Thank you so much! Bram Edited July 21, 2004 by bpribadi Share this post Link to post Share on other sites