or Connect
New Posts  All Forums:Forum Nav:

PPAS Build Thread. - Page 13

post #181 of 254
I'm thinking of using a LM4562/OPA132/BUF634 combination. I'm not too familiar with opamp characteristics, does anybody know under which BoM this would fall under (FET, Bipolar, ??)?
post #182 of 254
Bipolar. LM4562 is bipolar, and 10nA is still 2000 times the Ib of something like an OPA134. So even though it's a low Ib for a bipolar input op-amp it's still high such that you need to observe the same sort of build rules.
post #183 of 254
Cool, thanks for the info Filburt.

Ran into another problem today - remembered that Mouser was OOS on the SST502 part, and they won't be getting stock in for at least another 2 months. Same with digikey/newark.

Anybody know of any alternative part for this position, or better yet have a spare one to lend me? Thanks!
post #184 of 254
Hmm looking at ATAT's original BoM it looks like the SST502 is just for biasing into class A. I'll leave em out.

Ordered 2 too few of the SST310 though so will have to order some more of those. Oh well.
post #185 of 254
Got my SST310s today, soldered everything up. Works great! Getting around 8-11 mV of offset per channel, nothing serious. I guess I will leave it running overnight to see how it responds when the battery voltages dip. The LM4562/OPA132 sounds pretty great. More impressions later.
post #186 of 254
cool... Please post pictures!
post #187 of 254
Here's one



Just cased it up, looks very good so far. I am measuring around 9 mA per channel, if that's the correct way of measuring output then I guess it's using 20 around mA total, which seems a bit low to me...maybe it's because I haven't biased it to class A yet.

DC offset is stabilizing at 9mV per channel...pictures to come of it cased up.
post #188 of 254
ah... jumped the gun on the phone jack soldering... It has to go thru the case first...been there done that... I love those jacks though. very nice job Dan... looking forward to seeing it finished.
post #189 of 254
Quote:
Originally Posted by vixr View Post
ah... jumped the gun on the phone jack soldering... It has to go thru the case first...been there done that... I love those jacks though. very nice job Dan... looking forward to seeing it finished.
Yeah, I forgot about that in my hurry to get it working no matter though unsoldering/resoldering was a breeze. Here's the finished product..



I put in .1% 75 ohm resistors in line with the output since I will be using them mainly with Ety ER4Ps, for an instant P-S conversion. Unfortunately one of the resistor legs broke off when I was soldering, so right now it's being held on to the jack by a gob of solder. I hope it'll be enough to hold up through my trip abroad this summer.

As for sonic characteristics, it's not as warm as my Heed, which I think is because of the naturally 'clinical' characteristic of the PPA, and it's a little slow. Perhaps changing to the LMH buffers might be worthwhile...

Anyway, thanks again Rob for the board Good luck in building yours!
post #190 of 254
Dan,
Awesome! looks great. I hope you enjoy it, I hope to get around to building a couple of these soon. I would like to give one as a gift to my daughter, although she uses all my amps anyway...( and phones, cables, interconnects, battery chargers, i pod, laptop...) She says the CMoy type amps are a guy magnet...they all want to know "what is that thing?"
post #191 of 254
hey im just trying to order parts for my PPA, need a bit of help though, ive never done surface mount stuff before so im a little unsure. from the sounds of what people have said in this thread, as well as whast AVAILABLE to order online, i think im going to go with the LMH6321 buffers (of which i need 3 right), which do i want from digi key, they have 2 available.
LMH6321MR-ND

OR

LMH6321TS-ND

also, i wanted to go w/ the ad8066 as i hear it has good bass, for my opamp, bug again, several available through digi. could someone link me to the correct P/N for the one i should order, as well as a suitable ground channel opamp to use with it? preferably stuff thats available through digi key, if its not, a different opamp would probably suffice. THANKS guys, and sorry for being clueless
post #192 of 254
http://www.digikey.com/scripts/DkSea...428317&Site=CA

is that the one i want, if i wana go w/ the ad8066?
with something like
http://www.digikey.com/scripts/DkSea...871802&Site=CA
as a ground ompamp?

and then like i said in my last post, using 3 lmh6321 wiht those 2 would work well? am i on the right track?
post #193 of 254
Quote:
Originally Posted by el_matt0 View Post
hey im just trying to order parts for my PPA, need a bit of help though, ive never done surface mount stuff before so im a little unsure. from the sounds of what people have said in this thread, as well as whast AVAILABLE to order online, i think im going to go with the LMH6321 buffers (of which i need 3 right), which do i want from digi key, they have 2 available.
LMH6321MR-ND

OR

LMH6321TS-ND

Use the MR
here is a link: http://www.national.com/pf/LM/LMH6321.html
post #194 of 254
alright, what about my second to last post about the opamps. would the ones i have in mind be an appropriate choice? and if so, which of the various different ones should i get? tx i appreciate the help guys
post #195 of 254
Please help me choose opamps! I have 3 LMH6321's which seem to sound amazing (tried them without opamps, but they started to oscillate), and I don't want crap in front of them. Since the LMH's are 12 V max, and since I'm planning on using 7 x AAA = 8,4 V and fit everything in a Hammond C801, my choices are limited. At first I was aiming at AD744's but I don't think they'll sound good at that voltage (I haven't heard them, only AD746, and it doesn't sound good at 9 V). Neither will OPA2701. AD8058 lacks "body". OPA2132 and AD823 are just not good enough.

Maybe I'll go for LM4562 or AD8066, but what opamp will sound good in the ground position? I'm not fond of AD8610 (too harsh). Maybe I should remove the ground LMH6321 and use LMH6654 or AD8045 or some other high current opamp alone?
New Posts  All Forums:Forum Nav:
  Return Home