[HeadphoneAddict]

Well, it's also nice to now know that one could build their eXStatA with XLR only, and simply use a $10 set of Neutrik adapters to connect an SE source to the amp, with no easily discernible degradation in the sound (when listening at 3:30AM instead of sleeping). I have a nice Jensens Transformers ISOmax box to convert RCA>XLR and visa versa, but it isn't needed.

 

[les_garten]

Quote:

Originally Posted by HeadphoneAddict /img/forum/go_quote.gif Well, it's also nice to now know that one could build their eXStatA with XLR only, and simply use a $10 set of Neutrik adapters to connect an SE source to the amp, with no easily discernible degradation in the sound (when listening at 3:30AM instead of sleeping). I have a nice Jensens Transformers ISOmax box to convert RCA>XLR and visa versa, but it isn't needed.

This one?

Neutrik - Audio - Circular Adapters - NA2MPMF

 

[spritzer]

Quote:

Originally Posted by wiatrob /img/forum/go_quote.gif Of course, at $100 a board set, plus parts (and the time tracking them down - there's no published BoM or mouser project is there?) not in the same budget category. But I've yet to build one so I will defer to your experience. It is on my list as I'd like to compare the two amps someday.

The BOM is printed on the board so no need for one. Just go to Mouser and search for RN60 and use the built in selector to pick out all the values needed. I always buy 100 at a time but it isn't really needed. Next step would be to buy the heatsinks (2") and find red led's with a 1.7V voltage drop (you can go higher but then you need larger sinks). Order the transistors from bdent and you are done.

Quote:

Originally Posted by ericj /img/forum/go_quote.gif I think the simple differential tube amp got frowned on by me out of concerns over the use of popular out-of-production tubes. Not that i recall that it strictly used them. In retrospect a 6S4 version of that amp would be just fine, and i don't recall whether that's the default or not. I also might have whined about the potential cost of iron - I'm a cheap person and $50 for an off-the-shelf hammond makes me wince. Even though i know that to be an irrational response. One of my requirements was that it doesn't require an additional phase splitter, but i've come to understand that i needn't have worried. Can't tell you how happy i am that this all came to be, though.

The cost of iron is a non issue (30$ R-core is what I'm using in my latest version of the amp) and new production tubes aren't a problem either. The PSU could easily use a center tapped HV winding so all the cheap transformers out there come into play. My newest amp will use ECC83's and 7N7's built on a Koss ESP10 chassis but 6SN7's would also work.

 

[HeadphoneAddict]

Quote:

Originally Posted by les_garten /img/forum/go_quote.gif This one? Neutrik - Audio - Circular Adapters - NA2MPMF

That looks like it is what you want. However, after looking at that link I just noticed that with my having 4 different adapters, RCA jack to male XLR, RCA jack to female XLR, male-male XLR and female-female XLR, that all are Neutrik brand except for the "RCA jack to male" that I used for this experiment. See the one I used at the bottom of the next photo. I got both of the XLR>RCA connectors on ebay at the same time from 5150enterprises / webdealz at cox dot net, but I see that only the XLR female to RCA jack is the Neutrik brand, and the XLR male to RCA jack is some unknown brand.

I also used the ones that came with my SAC KH1000 amp, intended for people who needed to feed the amp via single ended sources. It has their own logo on it, and looks unlike the Neutrik in the smaller details.

 

[wiatrob]

Quote:

Originally Posted by spritzer /img/forum/go_quote.gif The BOM is printed on the board so no need for one. Just go to Mouser and search for RN60 and use the built in selector to pick out all the values needed. I always buy 100 at a time but it isn't really needed. Next step would be to buy the heatsinks (2") and find red led's with a 1.7V voltage drop (you can go higher but then you need larger sinks). Order the transistors from bdent and you are done.

I take it this is a different amp design than the one mentioned here:

http://www.head-fi.org/forums/1332600-post4.html

I know that thread's 4.5 years old...

 

[runeight]

Quote:

Originally Posted by spritzer /img/forum/go_quote.gif The BOM is printed on the board so no need for one. Just go to Mouser and search for RN60 and use the built in selector to pick out all the values needed. I always buy 100 at a time but it isn't really needed. Next step would be to buy the heatsinks (2") and find red led's with a 1.7V voltage drop (you can go higher but then you need larger sinks). Order the transistors from bdent and you are done. The cost of iron is a non issue (30$ R-core is what I'm using in my latest version of the amp) and new production tubes aren't a problem either. The PSU could easily use a center tapped HV winding so all the cheap transformers out there come into play. My newest amp will use ECC83's and 7N7's built on a Koss ESP10 chassis but 6SN7's would also work.

If I may offer a thought or two. Hopefully they will be helpful.

Regarding the KGSS, I happen to think (for what my opinion is worth) that the KGSS is a pretty cool amp and a really nice design. I'm pretty sure that I said this in the original thread when contemplating taking on designing a new stat amp. May have even said it on another occasion too. And, in fact, I mean it.

I don't know how it performs in real life or how difficult/easy a build it is, but I imagine that it does perform very well and it has a nice high PP voltage capability, more than the eXStatA is designed to have.

In fact, I think enough of this amp that I think, Spritzer, it deserves its own thread, if it doesn't already have one or even several, where its design features, its board features, its PS featuers, its bias supply features can be put forth (beyond the HW article) and its builders can talk about it. Perhaps now is a good time to start one for those who are interested in building one.

As for alternatives to the eXStatA, there are at least a handful of these, including all-tube amps and other possible SS designs or hybrids. I can't say which would be better or what individual diyers might prefer to build. I certainly don't expect that every diy stat builder would think that the eXStatA has a corner on the diy amp market. It certainly does not. It simply does what it was designed to do at a reasonable cost. It does not do any more than that. We had a bit of discussion about alternatives on ericj's original thread and perhaps it is also worthy of more discussion on an new thread to explore some of those other possibilities. Although, as I think I said in my first post on this thread, there is hardly anything new under the sun in analog audio. Every single subcircuit in the eXStatA has been done before. Maybe even the whole amp has been done before, I just simply could not find anything in the places where I could search. As nearly as I an tell from what I know, every subcircuit in the KGSS or the BH or Andreas' amps have been done before. Sometimes, these days, someone comes up with a new combination or a better refinement, but the fundamental building blocks haven't really changed much. Diff amps, current mirrors, Vbe multipliers, followers, splitters, CCSs, cascodes, etc. have been around the block many times. Some of them are older than I am and that makes them pretty ancient.

I certainly would enjoy reading those discussions and contributing if I had anything useful to add.

In the meantime gents, keep sending me your addresses and I will get the boards out. Most of them should go in the mail before the week is out.

Yours,
Dr. Cavalli
PhD, Plasma Physics
Thermonuclear Fusion

 

[wiatrob]

OK, Dr. C, I will stop hijacking the thread with discussions of other amps... and look forward to exploring other designs in their appropriate venues.

 

[macm75]

Quote:

Originally Posted by spritzer /img/forum/go_quote.gif I for one think the KGSS is easier to build then the exstata and just easy in general. Now the old PCB's were a giant PITA but the Headamp units are excellent and much easier to work with. No need to match to a certain value there and all the parts are easy to find. Locking shims FTW.

Out of curiousity, is the KGSS Headamp board designed to accept the "old" 2SK389 or the "new" LSK389?

Edit: sorry about the question. I did not see the top 2 posts while writing mine.

 

[spritzer]

If somebody wants to start a thread for a DIY KGSS then go ahead. I'm not going to (already built 3 and one more due soon) but I did want to correct the assumption that the KGSS is more complex then any of the AMB amps. Just because something doesn't have a BOM, doesn't make it complex. It's the same thought doesn't drive people to find subs for transistors that are OOP.

As for the other amp designs out there, most are easy to build and I'm a firm believer in people cutting their teeth on P-P wiring a circuit.

As for the circuits being used before, Andrea's amps do quite a bit more then just borrow from old Stax designs. I recently acquired a Stax schematic (yet to have it in my hands though) but from the pics it's clear where he got his SS design. Nothing wrong with it really until some bright spark decides to make it as a commercial model and then bad things happen.

Quote:

Originally Posted by wiatrob /img/forum/go_quote.gif I take it this is a different amp design than the one mentioned here: http://www.head-fi.org/forums/1332600-post4.html I know that thread's 4.5 years old...

Same one but the KGSS cost 1500 or even less back then. I also built a rather crazy version back in the day which has now been scrapped for parts, the top half now houses my BH amp section while the old PSU is now a complete KGSS. It would have made more sense to just buy one from Justin but I instead ordered the most expensive BH he built.

Quote:

Originally Posted by macm75 /img/forum/go_quote.gif Out of curiousity, is the KGSS Headamp board designed to accept the "old" 2SK389 or the "new" LSK389?

2SK389's or matched singles. LSK389's can easily be used if you bend the pins on the metal can version or use the SMD version with the clever little adapter. It isn't really an issue since 2SK389's are still plentiful and I've more then once been offered to buy 1000+ units recently.

 

[runeight]

Quote:

Originally Posted by spritzer /img/forum/go_quote.gif As for the circuits being used before, Andrea's amps do quite a bit more then just borrow from old Stax designs. I recently acquired a Stax schematic (yet to have it in my hands though) but from the pics it's clear where he got his SS design. Nothing wrong with it really until some bright spark decides to make it as a commercial model and then bad things happen.

Well, it is most certainly my limitation, but I don't know where to find old stax design schematics and don't know how many have been published. But, I can guess that even the older stax amps use circuit topologies that are principally a re-use of fundamental building blocks, although perhaps put together in clever ways by the stax designers.

I don't know Andreas personally, perhaps you do, but it is not certain to me that he simply derived his amp designs from stax designs. He may simply have come up with the ideas himself, but nonetheless made a similar design. Given the limited numbers of ways to do things, I think this is pretty common. How many power amplifiers use complementary output topologies? Millions. Yet when another designer uses one this does not make him a copy cat, he's just using proven design components. How many amps use constant current sources? Millions. Yet a new designer using one does not make him copy cat. And no commercial manufacturer is going to prevent someone from using a simple complementary O/P stage or a current source unless it includes particular and exclusively owned added features.

In my very first post to this thread I indicated that I had looked for circuits similar to the exstata on the web and did not find any. But, I also suggested that those of you who are more familiar with these designs would certainly say if there were indeed prior amps with the same design. Please feel free to do so now. I, for one, would be pleased to know the facts that I may not know now.

 

[Beefy]

Quote:

Originally Posted by spritzer /img/forum/go_quote.gif It's the same thought doesn't drive people to find subs for transistors that are OOP... ...As for the other amp designs out there, most are easy to build and I'm a firm believer in people cutting their teeth on P-P wiring a circuit.

Wiring is my least favourite part of a build, and dredging through datasheets my least favourite part of planning. Why would I want to do a build where I specifically have to dredge through datasheets, and do lots more wiring?

 

[ericj]

Quote:

Originally Posted by Beefy /img/forum/go_quote.gif Wiring is my least favourite part of a build, and dredging through datasheets my least favourite part of planning. Why would I want to do a build where I specifically have to dredge through datasheets, and do lots more wiring?

As i've said before, though, one of the reason i was looking for an amp with printed boards was that although I've built several amps with voltages mostly under 40v point-to-point, the potential for disaster building a complex point-to-point board with 1kv across it is just too great for most DIYers.

 

[luvdunhill]

Quote:

Originally Posted by runeight /img/forum/go_quote.gif And no commercial manufacturer is going to prevent someone from using a simple complementary O/P stage or a current source unless it includes particular and exclusively owned added features.

one of the most amazing things I've seen was TI recant on using Nelson Pass's "super-symmetry" topology. You know TI has the lawyer power to win, but it was very sportsman of them to admit they were wrong.

 

[runeight]

Maybe Nelson had better lawyers.

 

[Emooze]

Nelson Pass has one hell of a mustache. You don't mess with a man of that caliber.