CraigBuckingham

Last one first, eeeeeekk - acidbasement, you obviously don't practise law for a living. I like your diplomacy skullguise. The introduction letter is right, there are some good people around here. Thanks for the intro guys. Nothing like a good jostle. Torpedo, I understood your last post this time, but I can assure you that is not the case. As far as throwing egos and reputations around, I can see none of you gentleman would engage in such an exercise, not the least on someone else's behalf.

Oh my God, sorry Torpedo, I missed it, spritzer has a lot of posts, around 10,929. Sorry not going to be able to compete with that. I can only value add with some design and engineering advice. But not the real good stuff, I am am too old and wise to give away hard earned experience. It's worth too much money and how I make a living.

Torpedo, the Introduction Message, mmmmm, are you referring to "Don't mistake our familiarity with each other as familiarity with you,......" I am not sure if you noticed but it was spritzer who decided to exercise his familiarity with me, not the other way around. So what is so special about spritzer that I should know, I read his posts, I can't find it? It wasn't in the introduction message. :popcorn:

Hey guys, my skin is thick, I just thought who the heck is this guy. As far as it not being personal but about the post, well the post was written by me personally, so I have trouble seeing how a facepalm comment about my post could be seen as mutually exclusive from the person that wrote it. I read the welcome PM carefully, trust me. I also did a little research before I posted to get a feel who was who and doing what. I know KG and am familiar with his work. He may remember me from another headphone forum, we had some correspondence, I provided him with an original Stax SRM-313 schematic which he did not have at the time. As far as the caps, I choose caps on performance criteria, mainly dissipation factor. However the Jensens were just some of a few I tried. They were a lot better than the OEM caps in the SRM-313. The four poles better. It was the four poles I wanted to evaluate as that configuration I had not seen before, so I picked up some orange ones while I was at it. And the chokes made a very noticeable difference also. AFAIK, not many or may be any Stax use a CLC filtered power supply. In terms of what people are doing, I don't see many designing their own circuits for amplifiers or other electronic gear. I see spritzer using op-amps in audio equipment, notably OPA2604. Op-amps have no place in high quality audio reproduction, yes they are ok for making cheap hi-fi, but if you are serious about good audio then op-amps won't get you there. OPA2604 are so so as far as op-amps go, but the OPA627 or OPA637 (CL >5) leave them behind. It's a no contest. I gave up on op-amps about 15 years ago, because nothing you can do will fix up their problems. Not the least they use feedback and that's going to severely limit forward progress because of it, besides all their other limitations. I tried and I tried, including current sinking and sourcing the outputs for single ended class A operation and balancing the impedances seen by the input terminals. Both made big improvements, but a good discrete design relegated them into the spare parts box for repairs and non-audio work. Dusty Chalk, if you don't want to learn from other peoples knowledge good for you. But to qualify that statement for any one else here that does I think is a little too generous. Hope that's not too much writing in one post, but I tried to address everyone's comments in one go.

Hi spritzer, do I know you? You take very much liberty to make fun of me? Where did you gain this close familiarity with me to take such liberties? Usually only my close friends can joke with me this way. Anyway, if you are nice to me I may be willing to part some of my knowledge to help you improve your audio system.

Thanks chiguy, Sorry, ADHD got the better of me. Found the links afterwards. FWIW I found the stock caps in an SRM-313 I had to be very average, lacking colour and grainy. Nichicon from memory, but can't remember what type, although being HT ones may be easier to work out. Anyway, the Jensen ones were way more musical. Wow I thought it was 2014 this thread, did not look close enough. Used to some other faster moving forums.

Bit late on this one. What was the grid leakage current and what tube types, sorry don't have a schematic for that amp? I'll go looking in a minute. What caps did you use. Low dissipation factor ones, yes?

New to the forum. Are you just talking about swapping boxes or is this a technical forum where you guys don't mind getting your hands dirty and want to fix up some of the compromises inside? Bit of background, I had an SRM-313 SR-404 combo and a friend’s set of AKG-340 dynamic headphones (circ 1989) he picked up from a garage sale for $10 were kicking the butt of my Stax set-up. I was pretty disillusioned to say the least. I spent quite a bit of effort redesigning the power supply of the amp, (custom chokes, Jensen electolytics and a few other things) to have it finally jump a little bit ahead of the AKG-340. For me it wasn't enough to justify the expense so I put it back to standard, keeping all the good parts and put it up for sale on eBay. Got close to my money back as I bought direct from Japan at a good discount so it wasn't an expensive exercise.