Username 0 Report post Posted April 24, 2005 I was reading thru Tangents Pimeta tutorial and have some questions: http://www.tangentsoft.net/audio/pimeta/misc/schematic1.pdf What is the little "X" below C1, is it of any significance? Is Q1 and Q2 necessary? If I omit them, would there be any significant degradation in sound? How do I connect the pins on Q1 and Q2? Thanks. Share this post Link to post Share on other sites
heady 0 Report post Posted April 24, 2005 I was reading thru Tangents Pimeta tutorial and have some questions: http://www.tangentsoft.net/audio/pimeta/misc/schematic1.pdf What is the little "X" below C1, is it of any significance? Is Q1 and Q2 necessary? If I omit them, would there be any significant degradation in sound? How do I connect the pins on Q1 and Q2? Thanks. Hi username, the X means if you intend to put in C1, you have to cut the link where the X is. Q1 and Q2 together with R10 form the means of biasing the opamp to Class A operation which is higher quality sound at the cost of higher power consumption. The 3 parts together are optional. I have personally built this amp using project board but I think if you just want the amp, buy the board from Tangent, it isn't too expensive. Also buy the volume pot from him, the cheap one with the switch built in, plus the parts for Q1 and Q2. The other parts are easily available in SG. Unless you want to use the AD8620/10 then you can also buy those from him. His service is very good and swift. Share this post Link to post Share on other sites
Username 0 Report post Posted April 24, 2005 I am fairly confident in putting this together on a normal protoboard, it should be a good stepping stone to future projects. I guess I'll omit biasing it into class A operation since I will prolly be running them off 9-volts. Another thing is what does the rail splitter do? Share this post Link to post Share on other sites
skyskraper 0 Report post Posted April 24, 2005 http://tangentsoft.net/elec/vgrounds.html Share this post Link to post Share on other sites
Username 0 Report post Posted April 25, 2005 another question, can a dual IC OPAMP be used in place of a single IC opamp provided that I connec the pin outs accordingly? Share this post Link to post Share on other sites
skyskraper 0 Report post Posted April 25, 2005 yup, thats exactly how its done on the pimeta. dual for LR, single for ground. if you're creative you could probably even use a quad op amp for LRG Share this post Link to post Share on other sites
heady 0 Report post Posted April 25, 2005 another question, can a dual IC OPAMP be used in place of a single IC opamp provided that I connec the pin outs accordingly? username, that's exactly what I did for my Pimeta, I had two dual opamps and 3 buffers. But I am intending to experiment with removing the VG opamp and just use the LR Opamp and use only the buffer for VG. I know this will work as brpibadi's pimeta is exactly like this (1 dual opamp and 3 buffer) and sound just as good if not better. And uses less power, and that, is my desire, extending battery life. Share this post Link to post Share on other sites
Username 0 Report post Posted April 25, 2005 (edited) I realise that using a dual ic for my VG would save alot of hassle during connecting up my VG, that's nice to hear, I think the few dollars more is worth it. How does brpibadi's work without a VG and how long more is there battery life? EDIT: what kind of case would you reccomend for a Pimeta? Edited April 25, 2005 by Username Share this post Link to post Share on other sites
jasonhanjk 0 Report post Posted April 27, 2005 A sweet tin of course. Share this post Link to post Share on other sites
heady 0 Report post Posted April 27, 2005 I realise that using a dual ic for my VG would save alot of hassle during connecting up my VG, that's nice to hear, I think the few dollars more is worth it. How does brpibadi's work without a VG and how long more is there battery life? EDIT: what kind of case would you reccomend for a Pimeta? username, you can look at this thread for info on bpribadi's Pimeta clone: http://www.sgheadphones.net/index.php?showtopic=2571 I don't think it is a matter of cost but rather if it doesn't make a difference and it saves power consumption, why not? I have heard his Pimeta and honestly I can tell it sounds slightly better than mine. Of course, his has Class A biasing while mine doesn't. Bpribadi still uses a VG but just doesn't use an opamp but directly feed the VG to the buffer. If you look at Tangent's page on VG, this is one of the option. Actually, the current thinking over at Headfi is that using a TLE2426 is good enough. Share this post Link to post Share on other sites
heady 0 Report post Posted April 27, 2005 A sweet tin of course. For any 3-channel amp, the signal out ground is different from the signal in ground. If you use a sweet tin, the casing is tied to the signal in ground. So the output jack must be isolated from the case to avoid problems. Share this post Link to post Share on other sites
jasonhanjk 0 Report post Posted April 28, 2005 Actually Cmoy2 Signal and output ground I tied together, so no need to worry. Too bad I don't have my schemactic around anymore. Share this post Link to post Share on other sites
heady 0 Report post Posted April 28, 2005 Actually Cmoy2 Signal and output ground I tied together, so no need to worry. Too bad I don't have my schemactic around anymore. Hey, good to hear that. I can use my Hudson tin then. So sad to hear you have lost the schematics. Share this post Link to post Share on other sites
Username 0 Report post Posted April 28, 2005 Question: The specs of Pimeta says the cap C6 needs a 10pF 200v. But I bought 10pF 50v is that okay? Share this post Link to post Share on other sites
heady 0 Report post Posted April 28, 2005 Question: The specs of Pimeta says the cap C6 needs a 10pF 200v. But I bought 10pF 50v is that okay? Sure, 50V is more than the power supply voltage for the Pimeta. You will fry the chips before you fry the cap Share this post Link to post Share on other sites
