Hi JoshK,
I had quite forgotten about this thread. I haven't built any valve stuff as yet, mostly for financial reasons. I have been fiddling about with transistors (they cost next to nothing and give surprisingly good results.)
I have every intention of trying the 5687 in the next few months, and may even try using it as a gain stage with a class A transistor buffer after it.
If you are interested, I have built a simple class A 3-transistor buffer (which you can find on Decibel Dungeon) and it has a very good sound indeed, though the output impedence is not as low as I would like. I tried a number of different transistors in it and you can find my comments on the site (look for Will). If you need six buffers, this might be a good way to go. The power supply is +/- 15v, so this should be a lot cheaper to build (and a lot safer) than a valve PS.
I am currently in the process of building a "diamond buffer" which is a bit more complex, but should give lower impedence and more current.
If you want to know more, it will be my pleasure.
Regards,
William.
I had quite forgotten about this thread. I haven't built any valve stuff as yet, mostly for financial reasons. I have been fiddling about with transistors (they cost next to nothing and give surprisingly good results.)
I have every intention of trying the 5687 in the next few months, and may even try using it as a gain stage with a class A transistor buffer after it.
If you are interested, I have built a simple class A 3-transistor buffer (which you can find on Decibel Dungeon) and it has a very good sound indeed, though the output impedence is not as low as I would like. I tried a number of different transistors in it and you can find my comments on the site (look for Will). If you need six buffers, this might be a good way to go. The power supply is +/- 15v, so this should be a lot cheaper to build (and a lot safer) than a valve PS.
I am currently in the process of building a "diamond buffer" which is a bit more complex, but should give lower impedence and more current.
If you want to know more, it will be my pleasure.
Regards,
William.
Hi Joel,
Your design is most interesting! It looks very well done, however may be a bit steep to do a 6 channel version, but I may try it for a 2 channel pre in my second system to see how I like it. Did you get the Jensens from the GP? What 6DJ8's are you using? Have you found this pre to show the differences in tubes?
I might be able to do without the input trannies as I am using this after my DEQX (if I use on active system) which should be ok with the load.
William,
Thanks for your offer. At this point I want to continue exploring the tube avenue, as my system already works fine with all SS design but I'd like to add a little bit of "love" to the chain. Good luck with your endeavors though.
Your design is most interesting! It looks very well done, however may be a bit steep to do a 6 channel version, but I may try it for a 2 channel pre in my second system to see how I like it. Did you get the Jensens from the GP? What 6DJ8's are you using? Have you found this pre to show the differences in tubes?
I might be able to do without the input trannies as I am using this after my DEQX (if I use on active system) which should be ok with the load.
William,
Thanks for your offer. At this point I want to continue exploring the tube avenue, as my system already works fine with all SS design but I'd like to add a little bit of "love" to the chain. Good luck with your endeavors though.
Hi Josh,
I got the input transformers direct. They take phone orders from the general public, and there's no minimum.
http://www.jensen-transformers.com
I haven't tube-rolled with the preamp yet, other than the few cases mentioned on the project web page. I'm using the Sovtek 6922 right now, and I like it.
Joel
http://www.joeltunnah.com
I got the input transformers direct. They take phone orders from the general public, and there's no minimum.
http://www.jensen-transformers.com
I haven't tube-rolled with the preamp yet, other than the few cases mentioned on the project web page. I'm using the Sovtek 6922 right now, and I like it.
Joel
http://www.joeltunnah.com
Hi William,
There is also the Aikido linestage, I built one and I like it a lot much better than the single 5687. I have heard a nice 12b4 pre but every 12b4 I ever bought was too microphronic to use but that’s just me. Do a quick search on this forum and you will find lot’s of info.
Some advantages are; a lot of flexibility with tubes, most anything with the same pin out will work.
It is very tolerant of a less then perfect power supply.
As for power chokes. If your guy can wind a transformer, he can wind a choke. We just have to tell him what size wire to use, and fill up the bobbin.
I am looking at a catalog and say for a core size (IE) of about 6x5 cm I’ll guess 2cm thick. There is a 15H, 30ma choke with a DC resistance of about 1k . I don’t know what gauge wire this might be but I bet someone here does…John
There is also the Aikido linestage, I built one and I like it a lot much better than the single 5687. I have heard a nice 12b4 pre but every 12b4 I ever bought was too microphronic to use but that’s just me. Do a quick search on this forum and you will find lot’s of info.
Some advantages are; a lot of flexibility with tubes, most anything with the same pin out will work.
It is very tolerant of a less then perfect power supply.
As for power chokes. If your guy can wind a transformer, he can wind a choke. We just have to tell him what size wire to use, and fill up the bobbin.
I am looking at a catalog and say for a core size (IE) of about 6x5 cm I’ll guess 2cm thick. There is a 15H, 30ma choke with a DC resistance of about 1k . I don’t know what gauge wire this might be but I bet someone here does…John
John, excellent feedback! I was concerned about the NFB inherent to the Aikido project. (so does the simple 5687 though). I have in general comes to believe NFB is a bad thing most of the time (not all).
Joel, I think your project looks most excellent. I'd love to build it, when I get some time, I think I will. You should come hear my system at some point, since you are local.
Josh
Joel, I think your project looks most excellent. I'd love to build it, when I get some time, I think I will. You should come hear my system at some point, since you are local.
Josh
Hi Josh,
To some extent there is feedback in most everything , somehow, someway,
There is not a ‘global feedback loop' in either of these circuits.
As to the Aikido, maybe are you thinking of the way PS noise is canceled?
Anyway, the feedback in both circuits is local, or degenerative feedback . which for the most part (broad stroke here) is good, IMHO, if it doesn’t kill your gain too much.
Global feedback, I try to do without but it is a valid tool.
But remember, if your only tool is a hammer, then every problem is a nail…John
To some extent there is feedback in most everything , somehow, someway,
There is not a ‘global feedback loop' in either of these circuits.
As to the Aikido, maybe are you thinking of the way PS noise is canceled?
Anyway, the feedback in both circuits is local, or degenerative feedback . which for the most part (broad stroke here) is good, IMHO, if it doesn’t kill your gain too much.
Global feedback, I try to do without but it is a valid tool.
But remember, if your only tool is a hammer, then every problem is a nail…John
I don't profess to know much about feedback, just that in my limited experience those commercial designs I have heard that don't use it (global?) seem to have a more correctness about them. Well ultimately it will come down to building numerous different designs myself and learning for myself. Anything else wouldn't be DIY.
A friend of mine has built an Aikido (using 6n1p's and 5687's). It was definitely an improvement on his previous (very good) valve preamp. It sounds very special in his system, but when we tried it in my system I was pretty disappointed. Not that it sounded bad, but I had expected a lot more. Perhaps if we tried it again now, it would sound better, since I am continually upgrading and tweaking everything I can think of. My only beef with valve designs is that they seem to lack current delivery compared to SS designs.
My mid/tweeter amp is a hybrid design, and I am very happy with the mix of valve and SS sound. My thoughts are to eventually build a single ended class A hybrid preamp, using transistor input stage, valve VAS and transistor output. All 3 stages would have to have local feedback but i would try to avoid global feedback. Right now, i am busy experiemnting and learning as a necessary step in the process of reaching that goal.
My mid/tweeter amp is a hybrid design, and I am very happy with the mix of valve and SS sound. My thoughts are to eventually build a single ended class A hybrid preamp, using transistor input stage, valve VAS and transistor output. All 3 stages would have to have local feedback but i would try to avoid global feedback. Right now, i am busy experiemnting and learning as a necessary step in the process of reaching that goal.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.