RH 2nd generation - like RH88
Hi to all!
I can see that there is a lot of intrest in the 2nd generation of RH amps. Point is that this is really quite a different schematics when compared to the usual (and the RH schematics) because the anode of the driver is connected directly to the anode of the output tube (i.e. both are "below" the output transformer. It works like a charm 🙂 but is very difficult to design (a lot of thinking and calculation involved).
I did build one and it is everything I hoped for. The project was originally backed in the refinement stage by BTW -- but in the meantime my twins were born and frankly work on the RH series was paused. Now that the boys are 3 years old, I am trying to resume with new models.
Until this moment, there are two RH 2nd generation schematics, one for the RH88 (you can use KT88, 6550, and similar, obvioulsy) and another for the 300B. The 300B version was never built, mainly because I had not had the time to devote to building a prototype, but also due to the fact that "no one is a prophet in his own village", which means that while I might have some reputation on the net and around the globe, those nearest to me who could most benefit are actually fascinated with other amps whose "authors" are more willing to pose as gurus.
I am not inclined to post those schematics just like that on the forum, but can mail to those who want to give it a try -- particularly to those who would try the 300B version.
Of course, I believe all interested know my email address 🙂
And yes, for the RH88 2.5k to 3k primary is optimal, taking care that the output tube will draw approx. 100mA of DC current (must be adequate primary winding and gap).
Regards,
Alex
Hi to all!
I can see that there is a lot of intrest in the 2nd generation of RH amps. Point is that this is really quite a different schematics when compared to the usual (and the RH schematics) because the anode of the driver is connected directly to the anode of the output tube (i.e. both are "below" the output transformer. It works like a charm 🙂 but is very difficult to design (a lot of thinking and calculation involved).
I did build one and it is everything I hoped for. The project was originally backed in the refinement stage by BTW -- but in the meantime my twins were born and frankly work on the RH series was paused. Now that the boys are 3 years old, I am trying to resume with new models.
Until this moment, there are two RH 2nd generation schematics, one for the RH88 (you can use KT88, 6550, and similar, obvioulsy) and another for the 300B. The 300B version was never built, mainly because I had not had the time to devote to building a prototype, but also due to the fact that "no one is a prophet in his own village", which means that while I might have some reputation on the net and around the globe, those nearest to me who could most benefit are actually fascinated with other amps whose "authors" are more willing to pose as gurus.
I am not inclined to post those schematics just like that on the forum, but can mail to those who want to give it a try -- particularly to those who would try the 300B version.
Of course, I believe all interested know my email address 🙂
And yes, for the RH88 2.5k to 3k primary is optimal, taking care that the output tube will draw approx. 100mA of DC current (must be adequate primary winding and gap).
Regards,
Alex
Alex, I would love to have copies of these schematics if possible. You can send them to jim(at)printacg(dot)com. As I mentioned in another thread, the 84 design is excellent, I have used it as a stepping stone to build a sv83 version (sv83 needs a much lower value cathode r, and lower screens, which I established with a vr tube). It is also an very nice sounding amp, although I cheaped out on output irons, using a hammond 125ese as output choke and parafeeding to a hammond 1615 being used as output transformer.
Hi Alex,
Great to see you back.. Can you email me the circuit for the RH88 and RH300B ... I lost your emails when my HD crashed ...
Great to see you back.. Can you email me the circuit for the RH88 and RH300B ... I lost your emails when my HD crashed ...
LOST EMAILS RENEWED CONTACTS
Hi, BTW!
So, that is why we lost contact? Frankly, I never lost a file in my life, but have the bad habit of not importing old emails when I reinstall everything (at major PC upgrades). I guess the result is the same 🙁
I believe you have also never built the RH88 with addendum mods for the particularly nice tetrode tube 🙂 Well, there is always a second chance.
To all:
You can find my email on my website www.tubeaudio.8m.com
all of those who seriously want to try building one of the second generation RH amps, please send an email and I will forward you the schematics.
Regards to all,
Alex
Hi, BTW!
So, that is why we lost contact? Frankly, I never lost a file in my life, but have the bad habit of not importing old emails when I reinstall everything (at major PC upgrades). I guess the result is the same 🙁
I believe you have also never built the RH88 with addendum mods for the particularly nice tetrode tube 🙂 Well, there is always a second chance.
To all:
You can find my email on my website www.tubeaudio.8m.com
all of those who seriously want to try building one of the second generation RH amps, please send an email and I will forward you the schematics.
Regards to all,
Alex
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