EL84SE amp
Usually, what we find at first is the best... although we seldom recognise it.
If you ask (me), I would say that you should bild the RH84 amp you found as an interesting choice among the first few amps mentioned... and for the moment, stick to that.
How do I know that it's any good? Well, it's my brainchild, and I also did build it and experiment with it with a whole variety of driver tubes etc.
What this design lacks is commercialization and too much modesty: I should have named it "the slayer of the Zen", and that would do for everyone...
If you need any help, just e-mail me.
Best regards to all...
Aleksandar
(tired of being modest and reading lots of mumbo-jumbo by people who did not give too much of a tought to what they are saying/writing)
Usually, what we find at first is the best... although we seldom recognise it.
If you ask (me), I would say that you should bild the RH84 amp you found as an interesting choice among the first few amps mentioned... and for the moment, stick to that.
How do I know that it's any good? Well, it's my brainchild, and I also did build it and experiment with it with a whole variety of driver tubes etc.
What this design lacks is commercialization and too much modesty: I should have named it "the slayer of the Zen", and that would do for everyone...
If you need any help, just e-mail me.
Best regards to all...
Aleksandar
(tired of being modest and reading lots of mumbo-jumbo by people who did not give too much of a tought to what they are saying/writing)
Re: Re: EL84SE amp
http://www.tubecad.com/march2001
and also look at Gary Pimm's site for his PP47, which cronicles the progress from a triode driver to a pentode (I only built the pentode).
It's all explained here.planet10 said:
http://www.tubecad.com/march2001
and also look at Gary Pimm's site for his PP47, which cronicles the progress from a triode driver to a pentode (I only built the pentode).
Rfb
The Rfb between the anode of the output tube and the anode of the driver tube makes the whole circuit behave in a different way than usual. The driver acts as a current amplifier, while the output tube acts as a current/voltage converter.
Yes, John Broskie wrote an article on the subject, concerning mainly 5965 as driver and 300B as output tube... but that is a slightly (if not completely different cup of tea). When it comes to the other mentioned design explanation, I would not know, I have to look for it on the web.
Originality? Well, it is my opinion that "hot water" was invented a long time ago, especially when it comes to electronic tubes and circuits. Still, I would say that this approach has something of its own going on... therefore I do consider it original.
There is mention of the Zen amp by Decware, and I believe I mentioned something about renaming my amp "The Slayer of Zen" in order to make it more popular. Does anyone want to know why this amp is muuuuuch better than the Zen?
Regards to all!
The Rfb between the anode of the output tube and the anode of the driver tube makes the whole circuit behave in a different way than usual. The driver acts as a current amplifier, while the output tube acts as a current/voltage converter.
Yes, John Broskie wrote an article on the subject, concerning mainly 5965 as driver and 300B as output tube... but that is a slightly (if not completely different cup of tea). When it comes to the other mentioned design explanation, I would not know, I have to look for it on the web.
Originality? Well, it is my opinion that "hot water" was invented a long time ago, especially when it comes to electronic tubes and circuits. Still, I would say that this approach has something of its own going on... therefore I do consider it original.
There is mention of the Zen amp by Decware, and I believe I mentioned something about renaming my amp "The Slayer of Zen" in order to make it more popular. Does anyone want to know why this amp is muuuuuch better than the Zen?
Regards to all!
Viva Zemun!
Another tube dude and great guru from Zemun!
http://www.tubeaudiolab.co.yu/
Dobrodosao Alexandre!
Regards,
Yugovitz
Another tube dude and great guru from Zemun!
http://www.tubeaudiolab.co.yu/
Dobrodosao Alexandre!
Regards,
Yugovitz
RH84 vs Zen
The reasons why the RH84 is far better than the Zen:
1. Driver tube
In the Zen, the driver tube is an ECC88, which by definition is not the best and most musical audio tube (OK, arguably and argumentative) -- but the main issue is the operating point for this tube. In order to function well, the ECC88 generally needs some 10mA of current, while in the Zen such conditions are not met.
The RH84, on the other hand, has an ECC81 (or any equivalent) as driver, which tube is much closer to being a true audio tube (argumentative) -- the issue being that in this case operating point requirements are met and the tube does not run a low current (for those who know what am I writing about, a bad choice of operating tube is letting it work on the low very curved part of the curve as shown in datasheets...).
2. Power
The Zen is presented as 5W per channel, which might only be P.M.P.O. like chinese cheapo speakers for PCs. In effect, it does only afford some approx. 1.5W RMS, since the tube is operated in triode mode.
On the other hand, the RH84 was designed to give 4W RMS at 1% distortion (approximately) -- and does so by operating in pentode mode. Some might immediately argue that in this case, the Zen must have a better sound since it does not operate in pentode mode or adopt NFB, but those some would be wrong, since in the RH84 the tube sounds almost identical, not to say identical in pentode mode and in triode mode (a switch might be implemented to choose from pentode to triode mode, in the latter case obviously disconnecting the resistor between the anode of the output tube and the anode of the driver tube, and obviously redirecting the connection of the g2 to the anode in order to make it "triode mode").
How is that possible? Let us skip momentarily a longer explanation and just say that there is (and should be) a huge difference between scribbling some schematic and eventually making it work, and on the other hand, doing some research and investing some time in really designing some amp...
3.
Power supply
The Zen does apply a tube rectifier to its power supply -- making it immediately sound better than if it were simple SS diodes. But, the power supply is not that sound, since chokes are not applied and the value of the capacitors and eventual smoothing resistors does not lead to a particularly low ripple on the B+. Of course, chokes are costly, are they not?! Come on...
The power supply of the RH84 is a completely different affair -- however you build it, you should stick to the guidance given on the schematics. With a tube rectifier, followed by even a simple combination like 47uF - 10H choke - 220uF, the ripple is much much lower than in the Zen, while the sound is also much improved by adopting even such a simple solution.
4.
Last but not least, of those issues that immediately get to the eye of the experienced viewer of schematics, there is a shared cathode resistor for both output tubes, meaning both output channels, in the Zen. I just cannot believe that... but that is what the schematics show, and what can be seen in pics of the interior. Well, if it is really true, we are talking about channel mixing, not channel separation: that such form of masking can lead to some mellow or interesting or whatever sound, can be immagined... but I truly do not know how to expect a soundstage from an amp that has poor separation?!
When it comes to the RH84, well, separation could be better only if the power supply was split as well and the amp built as monos... but beside that, no such design flaws (or elaborate plots to mask deficiencies caused by poor whatever wherever in the amp).
I sincerely believe that these 4 points are enough even for neophites to get a glimps of the differences between the amps in question.
Inflamatory? I do not think so. When it comes to those who like cloning amps, as they call it, just clone the RH84. For the others, who paid for their Zen and might now feel offended -- there are several simple solutions, like buying a choke and substituting a "smoothing" resistor with the choke they bought... exchanging resistors on the driver tube in order to achieve a better operating point... or stripping the nice chassis of the superfluous parts, adding a choke and remaking it as an RH84... whatever they choos, even sticking to their amp, is their own choosing now.
Regards to all -- for details of the schematic, I remind you to look for them on my site, www.tubeaudio.8m.com !
Regards to Mr. Tito, as well... Zemun rules!
The reasons why the RH84 is far better than the Zen:
1. Driver tube
In the Zen, the driver tube is an ECC88, which by definition is not the best and most musical audio tube (OK, arguably and argumentative) -- but the main issue is the operating point for this tube. In order to function well, the ECC88 generally needs some 10mA of current, while in the Zen such conditions are not met.
The RH84, on the other hand, has an ECC81 (or any equivalent) as driver, which tube is much closer to being a true audio tube (argumentative) -- the issue being that in this case operating point requirements are met and the tube does not run a low current (for those who know what am I writing about, a bad choice of operating tube is letting it work on the low very curved part of the curve as shown in datasheets...).
2. Power
The Zen is presented as 5W per channel, which might only be P.M.P.O. like chinese cheapo speakers for PCs. In effect, it does only afford some approx. 1.5W RMS, since the tube is operated in triode mode.
On the other hand, the RH84 was designed to give 4W RMS at 1% distortion (approximately) -- and does so by operating in pentode mode. Some might immediately argue that in this case, the Zen must have a better sound since it does not operate in pentode mode or adopt NFB, but those some would be wrong, since in the RH84 the tube sounds almost identical, not to say identical in pentode mode and in triode mode (a switch might be implemented to choose from pentode to triode mode, in the latter case obviously disconnecting the resistor between the anode of the output tube and the anode of the driver tube, and obviously redirecting the connection of the g2 to the anode in order to make it "triode mode").
How is that possible? Let us skip momentarily a longer explanation and just say that there is (and should be) a huge difference between scribbling some schematic and eventually making it work, and on the other hand, doing some research and investing some time in really designing some amp...
3.
Power supply
The Zen does apply a tube rectifier to its power supply -- making it immediately sound better than if it were simple SS diodes. But, the power supply is not that sound, since chokes are not applied and the value of the capacitors and eventual smoothing resistors does not lead to a particularly low ripple on the B+. Of course, chokes are costly, are they not?! Come on...
The power supply of the RH84 is a completely different affair -- however you build it, you should stick to the guidance given on the schematics. With a tube rectifier, followed by even a simple combination like 47uF - 10H choke - 220uF, the ripple is much much lower than in the Zen, while the sound is also much improved by adopting even such a simple solution.
4.
Last but not least, of those issues that immediately get to the eye of the experienced viewer of schematics, there is a shared cathode resistor for both output tubes, meaning both output channels, in the Zen. I just cannot believe that... but that is what the schematics show, and what can be seen in pics of the interior. Well, if it is really true, we are talking about channel mixing, not channel separation: that such form of masking can lead to some mellow or interesting or whatever sound, can be immagined... but I truly do not know how to expect a soundstage from an amp that has poor separation?!
When it comes to the RH84, well, separation could be better only if the power supply was split as well and the amp built as monos... but beside that, no such design flaws (or elaborate plots to mask deficiencies caused by poor whatever wherever in the amp).
I sincerely believe that these 4 points are enough even for neophites to get a glimps of the differences between the amps in question.
Inflamatory? I do not think so. When it comes to those who like cloning amps, as they call it, just clone the RH84. For the others, who paid for their Zen and might now feel offended -- there are several simple solutions, like buying a choke and substituting a "smoothing" resistor with the choke they bought... exchanging resistors on the driver tube in order to achieve a better operating point... or stripping the nice chassis of the superfluous parts, adding a choke and remaking it as an RH84... whatever they choos, even sticking to their amp, is their own choosing now.
Regards to all -- for details of the schematic, I remind you to look for them on my site, www.tubeaudio.8m.com !
Regards to Mr. Tito, as well... Zemun rules!
Zemun
Just a few words about what Zemun is, for those who would like to know...
To say that Zemun is a suburb of Belgrade, is simply derogative. Zemun is one of the several municipalities of Belgrade, and before WWII was a city on its own. In Austria-Hungary times, it was a border city of relative importance since it overlooks the Danube, just like Belgrade on the other bank. Furthermore, Zemun-polje might be a suburban area of Belgrade (and Zemun).
After WWII, Belgrade was enlarged by claiming marsh ground on the affluence of the rivers Danube and Sava. The new part of the city, quite large, is now known as New Belgrade, and has connected directly Zemun to Belgrade -- thus Zemun has become a municipality of Belgrade.
By the way, Belgrade has approx. 2 million inhabitants, which is quite large by Central-European standards.
Last but not least, Zemun "houses" quite a lot tube "gurus" and audiophiles... most certainly by coincidence -- but that does not stop me from calling it the Tube Capital of this part of the world. Some of these are quite known, like Mr. Vukusic. What distinguishes me is the fact that I am not at all commercial, meaning that my projects have never been sold or bought.
Maybe some day, when I emigrate somewhere else, there will be some "Kitic audio design", or the like of it. For now, strict hobby.
Regards to all, Alexandar
Just a few words about what Zemun is, for those who would like to know...
To say that Zemun is a suburb of Belgrade, is simply derogative. Zemun is one of the several municipalities of Belgrade, and before WWII was a city on its own. In Austria-Hungary times, it was a border city of relative importance since it overlooks the Danube, just like Belgrade on the other bank. Furthermore, Zemun-polje might be a suburban area of Belgrade (and Zemun).
After WWII, Belgrade was enlarged by claiming marsh ground on the affluence of the rivers Danube and Sava. The new part of the city, quite large, is now known as New Belgrade, and has connected directly Zemun to Belgrade -- thus Zemun has become a municipality of Belgrade.
By the way, Belgrade has approx. 2 million inhabitants, which is quite large by Central-European standards.
Last but not least, Zemun "houses" quite a lot tube "gurus" and audiophiles... most certainly by coincidence -- but that does not stop me from calling it the Tube Capital of this part of the world. Some of these are quite known, like Mr. Vukusic. What distinguishes me is the fact that I am not at all commercial, meaning that my projects have never been sold or bought.
Maybe some day, when I emigrate somewhere else, there will be some "Kitic audio design", or the like of it. For now, strict hobby.
Regards to all, Alexandar
Alexander,
since this was meant to me.....
it was not meant derogative at all. I just recalled from my several trips to Belgrade that there is one part of town called Zemun. Going from sava river on the highway to the airport or past to the border you automatically come by Zemun.
rdgs
Oliver
PS Sorry for being way off-topic!!!!
since this was meant to me.....
it was not meant derogative at all. I just recalled from my several trips to Belgrade that there is one part of town called Zemun. Going from sava river on the highway to the airport or past to the border you automatically come by Zemun.
rdgs
Oliver
PS Sorry for being way off-topic!!!!
No comments?
Well, either I do not know exactly how forums function, or there is some other answer to it: but, after the post about the differences between RH84 and the Zen amp, I actually expected there would be various opinions emerging...
Instead, only a reply about Zemun (it's OK, since I was not born in Zemun -- but it would not have been if I were, as they are very proud and vindicative). No one has yet said anything, neither to defend the "accused" Zen and its author, nor to contribute in any manner.
Is it that people do not review new posts on forums regularly -- or maybe after that no one has anything to say?!
Well, that would be it. Regards to all.
Well, either I do not know exactly how forums function, or there is some other answer to it: but, after the post about the differences between RH84 and the Zen amp, I actually expected there would be various opinions emerging...
Instead, only a reply about Zemun (it's OK, since I was not born in Zemun -- but it would not have been if I were, as they are very proud and vindicative). No one has yet said anything, neither to defend the "accused" Zen and its author, nor to contribute in any manner.
Is it that people do not review new posts on forums regularly -- or maybe after that no one has anything to say?!
Well, that would be it. Regards to all.
Re: No comments?
No. It's just that people are probably on holidays!
I might have some comments on the way. It's no real secret that the Zen is not a marvel of circuit design. It probably would have been a boring circuit to look at back in 1940, but that does not mean it does not perform well.
Alex Kitic said:
No. It's just that people are probably on holidays!
I might have some comments on the way. It's no real secret that the Zen is not a marvel of circuit design. It probably would have been a boring circuit to look at back in 1940, but that does not mean it does not perform well.
Re: RH84 vs Zen
You wanted some comments? You got some.
I haven't heard the Zen myself, nor the RH84. I'm just commenting on what I see here. So what I say will be questionable to say the least (well no one else seems to be commenting
)
Low current in input/driver valves is sadly something done rather often, perhaps out of ignorance, but I suspect because of power supply requirements. Yet, by allowing the input/driver triode to stray into the murky botton of the curves, the distortion produced may cancel with some of that produced by the output stage. (Of course, I don't know if the Zen was designed this way)
This is my main gripe with the Zen. Claiming that the power output is almost 3 times its actual power output is misleading. You can argue that the difference between 1.8 and 5 watts is not so important as other characteristics of an amplifier (especially is the buyer has efficient speakers), but In fact there is an article trying to justify the embellished power output specification on the site somewhere. (To be fair, it was never stated that 5W was continuous rated power, and somewhere else on the site it states that the 'real' power rating is 1.8W)
Saying that "in the RH84 the tube sounds almost identical" is very subjective. The ear may not be easily fooled but the mind is I'd expect at least some to say that two RH84s sound different if you told them one was triode-strapped (when it wasn't). Anyway, pentode mode need not be necessarily inferior to triode mode, it's just a different set of comporomises that have to be made. And it seems that you've managed the problems (high output impedance and higher distortion than triodes) with the local feedback around the output stage.
What can I say, chokes are heavy and expensive!
A shared cathode resistor has been done in other amps too, notably Bob Danielak's original Darling. Yes, they may cause channel mixing to some degree, but it shouldn't be too great as long as the resistor is adequately bypassed (i.e. the cathodes of both output valves are at a point which sufficiently mimics AC ground). I can't say whether the shared cathode resistor compresses, or indeed expands the stereo image (I haven't got an SE amp with that 'weird' arrangement).
Differences: Choke-filtered power supply in RH84, Pentode mode operation in RH84, different input/driver valve, individual bypassed cathode resistors.... um....
It's clear that you feel the RH84 is FAR superior to the Zen for several reasons, like increased power output, lower distortion? etc. But remember, that was the promise of solid state! The RH84 is probably the more complex design, and may very well measure better on paper, yet that doesn't mean that everyone will like it more (some may just like an anemic, distorted sound, who knows?)
Anyway, I hope I haven't offended you, and thanks for sharing the design and taking time to explain why you believe it's better than the Zen (I can't say whether I agree, I haven't heard either
) At the very least the RH84 is something a little different from lots of other boring designs out there, and that is refreshing. (Of course not saying that boring designs can't perform well )
Maybe some comments from some people who have actually heard both designs? Or maybe there aren't any such people around
Merry Chistmas to all
Edit: some formatting mistakes
You wanted some comments? You got some.
I haven't heard the Zen myself, nor the RH84. I'm just commenting on what I see here. So what I say will be questionable to say the least (well no one else seems to be commenting
)Alex Kitic said:
Low current in input/driver valves is sadly something done rather often, perhaps out of ignorance, but I suspect because of power supply requirements. Yet, by allowing the input/driver triode to stray into the murky botton of the curves, the distortion produced may cancel with some of that produced by the output stage. (Of course, I don't know if the Zen was designed this way)
This is my main gripe with the Zen. Claiming that the power output is almost 3 times its actual power output is misleading. You can argue that the difference between 1.8 and 5 watts is not so important as other characteristics of an amplifier (especially is the buyer has efficient speakers), but In fact there is an article trying to justify the embellished power output specification on the site somewhere. (To be fair, it was never stated that 5W was continuous rated power, and somewhere else on the site it states that the 'real' power rating is 1.8W)
Saying that "in the RH84 the tube sounds almost identical" is very subjective. The ear may not be easily fooled but the mind is
I'd expect at least some to say that two RH84s sound different if you told them one was triode-strapped (when it wasn't). Anyway, pentode mode need not be necessarily inferior to triode mode, it's just a different set of comporomises that have to be made. And it seems that you've managed the problems (high output impedance and higher distortion than triodes) with the local feedback around the output stage.What can I say, chokes are heavy and expensive!
A shared cathode resistor has been done in other amps too, notably Bob Danielak's original Darling. Yes, they may cause channel mixing to some degree, but it shouldn't be too great as long as the resistor is adequately bypassed (i.e. the cathodes of both output valves are at a point which sufficiently mimics AC ground). I can't say whether the shared cathode resistor compresses, or indeed expands the stereo image (I haven't got an SE amp with that 'weird' arrangement).
Differences: Choke-filtered power supply in RH84, Pentode mode operation in RH84, different input/driver valve, individual bypassed cathode resistors.... um....
It's clear that you feel the RH84 is FAR superior to the Zen for several reasons, like increased power output, lower distortion? etc. But remember, that was the promise of solid state! The RH84 is probably the more complex design, and may very well measure better on paper, yet that doesn't mean that everyone will like it more (some may just like an anemic, distorted sound, who knows?)
Anyway, I hope I haven't offended you, and thanks for sharing the design and taking time to explain why you believe it's better than the Zen (I can't say whether I agree, I haven't heard either
) At the very least the RH84 is something a little different from lots of other boring designs out there, and that is refreshing. (Of course not saying that boring designs can't perform well ) Maybe some comments from some people who have actually heard both designs? Or maybe there aren't any such people around
Merry Chistmas to all
Edit: some formatting mistakes
Quick anwer
For the moment, just a quick anwer to the only question that might look as urgent: the issue on whether there are "that many people who have heard any of the designs".
First of all, this is the first time I had approached any forum in all these years both as a "searcher" and "websiter" (name for a person who has a website of his own?). Partly because some of John Broskie's sarcasm when it comes to forums and posting has obviously gotten to me -- but also because usually a person with a certain level of knowledge and experience cannot find anything new reviewing posts on forums, no pun intended, since it is quite obvious that the forums are mainly "attended" by people with little experience and/or knowledge. No pun intended, again.
Now the answer -- yes, quite a lot of people have built some of the RH amps for themselves, the LAF version of preamps was built in a good number of clones "all over the world". To most people, my designs have been both a pleasure to listen, and an eye-opener of the sort.
But, I sincerely believe that none of these people is participating in this forum, so unless I i.e. email a link to some of them, I don't think anyone will know that it is the moment to "stand up and say".
And, for that matter, it is not. I regard this question as a little indiscretion of the sort - not offending (as I am not offended by those who distrust) but uncomfortable (like "when I do not know what else to say, I will say it"). Of course, I will not email links to this forum to friends so they can "defend me" -- I am quite capable of defending my ideas on my own.
As soon as I find the time, I will make another post about the other, technically more important issues than this purely personal that I just had to reply to before too many people see it The technical issues mainly regard the fact that we cannot simplify things to triode vs. pentode, especially if we take into account known facts that have created a bad reputation for pentodes. On the other hand, I do not believe that people like to listen to "poor" sounding equipment -- just that once they have invested in this equipment, they are too vain to recognize the fact that what they own is simply not good (enough).
Regards,
Aleksandar
For the moment, just a quick anwer to the only question that might look as urgent: the issue on whether there are "that many people who have heard any of the designs".
First of all, this is the first time I had approached any forum in all these years both as a "searcher" and "websiter" (name for a person who has a website of his own?). Partly because some of John Broskie's sarcasm when it comes to forums and posting has obviously gotten to me -- but also because usually a person with a certain level of knowledge and experience cannot find anything new reviewing posts on forums, no pun intended, since it is quite obvious that the forums are mainly "attended" by people with little experience and/or knowledge. No pun intended, again.
Now the answer -- yes, quite a lot of people have built some of the RH amps for themselves, the LAF version of preamps was built in a good number of clones "all over the world". To most people, my designs have been both a pleasure to listen, and an eye-opener of the sort.
But, I sincerely believe that none of these people is participating in this forum, so unless I i.e. email a link to some of them, I don't think anyone will know that it is the moment to "stand up and say".
And, for that matter, it is not. I regard this question as a little indiscretion of the sort - not offending (as I am not offended by those who distrust) but uncomfortable (like "when I do not know what else to say, I will say it"). Of course, I will not email links to this forum to friends so they can "defend me" -- I am quite capable of defending my ideas on my own.
As soon as I find the time, I will make another post about the other, technically more important issues than this purely personal that I just had to reply to before too many people see it
The technical issues mainly regard the fact that we cannot simplify things to triode vs. pentode, especially if we take into account known facts that have created a bad reputation for pentodes. On the other hand, I do not believe that people like to listen to "poor" sounding equipment -- just that once they have invested in this equipment, they are too vain to recognize the fact that what they own is simply not good (enough).Regards,
Aleksandar
Re: Quick anwer
Forums can be strange places sometimes. I'm sometimes inclined to agree with the sarcasm from people like John Broskie and Geoff Moss.....
Oh dear, I was trying to tread lightly! The intention of my second post was to elicit some discussion about the RH84, and maybe make the design better known to DIYers (at least those who frequent this forum)
When I said
Actually, I'm wondering why you said that the RH84 may be "a completely different cup of tea" to the John Broskie article. I admit I'm no master when it comes to circuit design, and was looking for an explanation to see what I've missed.
Agreed. There is no reason why pentodes must sound bad!
That's true too
Forums can be strange places sometimes. I'm sometimes inclined to agree with the sarcasm from people like John Broskie and Geoff Moss.....
Alex Kitic said:
Oh dear, I was trying to tread lightly! The intention of my second post was to elicit some discussion about the RH84, and maybe make the design better known to DIYers (at least those who frequent this forum)
When I said
I was expressing regret that I didn't belive there would be many people out there who had both amplifiers. Until reading this thread I had not seen the RH84, and thought it might me a new (or relatively unknown) design. I don't mean to attack or offendMaybe some comments from some people who have actually heard both designs? Or maybe there aren't any such people around
Actually, I'm wondering why you said that the RH84 may be "a completely different cup of tea" to the John Broskie article. I admit I'm no master when it comes to circuit design, and was looking for an explanation to see what I've missed.
Agreed. There is no reason why pentodes must sound bad!
That's true too
Hi,
Hello Alex,
Good to see you're discussing one of your amps here...
Regarding posting on a forum, Mr. Broskie may have had bad experiences with them in the past, I don't know, but don't let that stop you from sharing and helping others through their paces.
After all, it's not because we had to learn with our noses stuck in books and a soldering gun ready that everyone else has to as well.
Anyway, expect people to be skeptical. People always are.
The difference is, here they'll dare to tell you whereas they probably won't if they'd be standing next to you. (I know you're almost 7 foot tall...Kidding.)
BTW, the plate to plate feedback...Isn't that positive FB that's being applied. I only had a quick glance so I could be wrong.
Thanks for sharing your work with me, btw. I'll take a closer look ASAP.
Cheers,
Hello Alex,
Good to see you're discussing one of your amps here...
Regarding posting on a forum, Mr. Broskie may have had bad experiences with them in the past, I don't know, but don't let that stop you from sharing and helping others through their paces.
After all, it's not because we had to learn with our noses stuck in books and a soldering gun ready that everyone else has to as well.
Anyway, expect people to be skeptical. People always are.
The difference is, here they'll dare to tell you whereas they probably won't if they'd be standing next to you. (I know you're almost 7 foot tall...Kidding.)
BTW, the plate to plate feedback...Isn't that positive FB that's being applied. I only had a quick glance so I could be wrong.
Thanks for sharing your work with me, btw. I'll take a closer look ASAP.
Cheers,
fdegrove said:
Frank, just to save some time
, the feedback is negative, because the plate of the input/driver is at the same point as the grid of the output valve, and hence has the opposite phase to that of the plate of the output. Plate of output to grid of the input/driver would be positive (in a 2-stage design). Some more detail about (what I think Alex's output stage is functioning as) here Alex, I think I forgot to say this before, but thanks for sharing! It's always nice to see some new application of ideas.
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