EL84 RH SE SIM
Let me remind all those who are familiar with the RH amps series... this is a sim of the original RH84 with ECC81 driver and EL84 output tube.
I believe no comments are necessary. If the sim is wrong, so are many diyers who built it and enjoyed it, emphasizing its qualities as undistorted power output and good well defined bass... at least.
Regards,
Alex
Let me remind all those who are familiar with the RH amps series... this is a sim of the original RH84 with ECC81 driver and EL84 output tube.
I believe no comments are necessary. If the sim is wrong, so are many diyers who built it and enjoyed it, emphasizing its qualities as undistorted power output and good well defined bass... at least.
Regards,
Alex
Attachments
RH84 in PP mode SIM
No comment needed, except for an apoligy if the jpg is not readable enough: I had to squeeze it quite a bit to be able to upload.
I would never produced this jpg if I had not already simulated this amp a long time ago. I just do not have the time to do it right now. Do not pay attention at the simpleton concertina splitter, it's there just to make a point. If I were to build that one, I would use an input transformer (provided I had a good one) or made a long tail phase splitter.
Anyway, the SIM results are staggering... but maybe they are wrong... just maybe
Regards to all believers!
No comment needed, except for an apoligy if the jpg is not readable enough: I had to squeeze it quite a bit to be able to upload.
I would never produced this jpg if I had not already simulated this amp a long time ago. I just do not have the time to do it right now. Do not pay attention at the simpleton concertina splitter, it's there just to make a point. If I were to build that one, I would use an input transformer (provided I had a good one) or made a long tail phase splitter.
Anyway, the SIM results are staggering... but maybe they are wrong... just maybe
Regards to all believers!
Attachments
2ND HARMONICS
I really do not know where did you get that?!?!?! It is not like that at all!!!
Please do not mystify things that are straightforward, and do not dismiss what you have not tried as the urban myth of good sounding 2nd harmonics
I use the old Circuit Maker... with spice 3 models, approximately. When I cannot get a generally accepted model, I write one, based on the curves... not easy, but it pays off with correct results.
Regards,
Alex
I really do not know where did you get that?!?!?! It is not like that at all!!!
Please do not mystify things that are straightforward, and do not dismiss what you have not tried as the urban myth of good sounding 2nd harmonics
I use the old Circuit Maker... with spice 3 models, approximately. When I cannot get a generally accepted model, I write one, based on the curves... not easy, but it pays off with correct results.
Regards,
Alex
As expected, the mainly 2nd Harmonic cancels out perfectly in a P-P sim. But we have no idea here what models are being used for the tubes in the Sim. The usual simple 3/2 power law models produce mainly 2nd harmonic. Real tubes make higher harmonics when loaded down. How does the real RH84 measure with a soundcard FFT? Particularly for 3rd harmonic and above.
With 1% 2nd Harmonic (or maybe more for real hardware), this is quite hearable.
With 1% 2nd Harmonic (or maybe more for real hardware), this is quite hearable.
Hey Alex,
Try PNG instead, they seem to work better. I also had trouble with readability of JPGs before.
But remember we are talking PP here so low even order harmonics is what counts!
I have also simmed the Huey with Gingertubes SFs which of course gave more output before clipping but no better lowlevel behaviour.
I would have liked to see the Huey on top but sorry !
I am anyway building a ECL86 PP on the Huey theme as I really like the tube. Bought a great stock of NOS Tungsrams from Australia on eBay initially to be used as reverb-driver in my guitaramps.
Anyone else than Svein who cares to test this simple variation IRL? I get an indication of 50% lower 3rd....
Try PNG instead, they seem to work better. I also had trouble with readability of JPGs before.
But remember we are talking PP here so low even order harmonics is what counts!
I have also simmed the Huey with Gingertubes SFs which of course gave more output before clipping but no better lowlevel behaviour.
I would have liked to see the Huey on top but sorry
! I am anyway building a ECL86 PP on the Huey theme as I really like the tube. Bought a great stock of NOS Tungsrams from Australia on eBay initially to be used as reverb-driver in my guitaramps.
Anyone else than Svein who cares to test this simple variation IRL? I get an indication of 50% lower 3rd....
Attachments
BEFORE I GET TO SLEEP
Please take a look at the schematics and the various simulation diagrams. You will find all the analysis necessary there, showing you the various 2nd, 3rd and higher order distortions, if there are any.
Yes, the simulation of a PP amp can subtract nicely, better than in real life, the 2nd and even order harmonics -- but because those are subtracted in theory by the PP circuit itself. In the SE amps there is no such subtraction per se. When it comes to the remaining distortions, those are mainly odd order distortions for PP amps. The sim says something like 0.7%... I do not have the reason to doubt.
Of course, you can always build an output stage for testing and test on "real life" analysers But it will not do you any good for guitar amps where particular sound and distortion are welcome...
OK. I'm off to bed now... good night, don't let the bed bugs bite!
Please take a look at the schematics and the various simulation diagrams. You will find all the analysis necessary there, showing you the various 2nd, 3rd and higher order distortions, if there are any.
Yes, the simulation of a PP amp can subtract nicely, better than in real life, the 2nd and even order harmonics -- but because those are subtracted in theory by the PP circuit itself. In the SE amps there is no such subtraction per se. When it comes to the remaining distortions, those are mainly odd order distortions for PP amps. The sim says something like 0.7%... I do not have the reason to doubt.
Of course, you can always build an output stage for testing and test on "real life" analysers
But it will not do you any good for guitar amps where particular sound and distortion are welcome...OK. I'm off to bed now... good night, don't let the bed bugs bite!
Simulations are notoriously inaccurate for higher order distortions, especially with simplistic 3/2 power tube models. Surely you have tested the real thing with a sound card FFT? Every PC can do this.
I'm not trying to attack the RH84, It probably does sound very nice. But the claim was made above that loading the driver triode down does not make worse distortion. Even novice designers know this to be the case. For SE, a bit of 2nd Harmonic can sound quite nice to some.
One can of course also shift the operating points of the two tubes to program the level of 2nd Harmonic somewhat, since they are of opposite phase. Loading down the driver will likely cause some cancellation of the usually higher 2nd H distortion of the output. So the RH84 may actually have lower 2nd H than usual for SE. But, in general, loading down a triode's plate will cause higher odd harmonics, which cannot usually be nulled out by the 2nd stage op. point.
Don
I'm not trying to attack the RH84, It probably does sound very nice. But the claim was made above that loading the driver triode down does not make worse distortion. Even novice designers know this to be the case. For SE, a bit of 2nd Harmonic can sound quite nice to some.
One can of course also shift the operating points of the two tubes to program the level of 2nd Harmonic somewhat, since they are of opposite phase. Loading down the driver will likely cause some cancellation of the usually higher 2nd H distortion of the output. So the RH84 may actually have lower 2nd H than usual for SE. But, in general, loading down a triode's plate will cause higher odd harmonics, which cannot usually be nulled out by the 2nd stage op. point.
Don
Interesting stuff,
In the basic Baby Huey I can confirm that the plate to plate feedback does make the driver work much harder. You have to swing 2 to 3 times as much current in the diffamp triodes (depending on the level of feedback set by the cross coupling resistor). This gives the Baby Huey its 2nd harmonic rich profile which is where its apparent strong bass and rich mids sonics come from.
I like it like that. Certainly it can be "cleaned up" by using other circuit options but it would'nt sound like a Baby Huey anymore.
If I were repeating the mistakes of the last 30 years designing for 0.001% THD then I'd be using 3 legged fuses instead of tubes and would'nt be here at all.
Cheers,
Ian
In the basic Baby Huey I can confirm that the plate to plate feedback does make the driver work much harder. You have to swing 2 to 3 times as much current in the diffamp triodes (depending on the level of feedback set by the cross coupling resistor). This gives the Baby Huey its 2nd harmonic rich profile which is where its apparent strong bass and rich mids sonics come from.
I like it like that. Certainly it can be "cleaned up" by using other circuit options but it would'nt sound like a Baby Huey anymore.
If I were repeating the mistakes of the last 30 years designing for 0.001% THD then I'd be using 3 legged fuses instead of tubes and would'nt be here at all.
Cheers,
Ian
"My idea is that they are good enough to get indications in what direction the wind blows, when you compare alerations in a circuit using the same tube models."
Exactly
Until someone makes a PC tube curve tracer that interfaces with SPICE, it will remain a comparative tool as for distortions.
But very good for ballparking designs and component values.
Don
Exactly
Until someone makes a PC tube curve tracer that interfaces with SPICE, it will remain a comparative tool as for distortions.
But very good for ballparking designs and component values.
Don
Hi Ian,
The sims does not indicate more 2nd harmonic from the driver than in the other variations. Have no UL model though, but have tried both triode-strapping and pentode. On the contrary I get an indication of "richer" even order instead. About the first Huey, the too small coupling capsprobably interacts with the p-p NFB and gives a small rise at the low end, could this be "strong bass"?
The added SFs does not change this, it only allows the amp to go into AB2. So I guess this little amp sounds powerful!
But listening is what counts and ECC83 and EL84 PP is always is nice to listen to
! OT:
Hope it works out with your guitar amp. Instead of 6V6 you should try 7591A, have dumped 6V6 in favour of this one in my smaller amps, www.revintage.se
Just remembered I have an old ST-35 on the shelf waiting for rebuild. Great little amp with nice iron. The original idea was a symmetrical 6DJ8 driver with transformer input. Have earlier used it with ECC81 instead of ECC832/12DW7/7247 as this gave the best listening impression.
Maybe one should rebuild it with ECC83 and make it switchable between Huey- and Svein-style !
The Huey idea of lessening overall NFB and adding local over the output tubes is great! Will work best with UL though, with pentode Zout would be to high.
Maybe one should rebuild it with ECC83 and make it switchable between Huey- and Svein-style
! The Huey idea of lessening overall NFB and adding local over the output tubes is great! Will work best with UL though, with pentode Zout would be to high.
triode or pentode, that's the question
You guys are all using/simulating the triode mode of the output tube. Would the (relative) real world or sim results differ in the same way between these two modes if you compare two types of driver/feedback settlements with each other ?
About SE: Did anybody try to better the RH84 concept by adding some assistance from a so called three legged fuse on a strategic place ? Or is it "sacrilege" to experiment with something that is already perfect.
You guys are all using/simulating the triode mode of the output tube. Would the (relative) real world or sim results differ in the same way between these two modes if you compare two types of driver/feedback settlements with each other ?
About SE: Did anybody try to better the RH84 concept by adding some assistance from a so called three legged fuse on a strategic place ? Or is it "sacrilege" to experiment with something that is already perfect.
COMMENTS
To achieve notoriety there has to be common consense about that, and not dismissal of something as simplistic.
No, I have not tested "the real thing" with a sound card FFT, both because I did not need to, and because I did not want to devote my tim to it.
Did not need to means that nothing went horribly wrong in the way the amp works, and I cannot care less whether the distortions are 1% or 2% at 4W. Distortions you can hear, clipping you can hear, and output power you can measure extremely simply.
Further, if tube models are simplistic and notriously inaccurate, one could object that sound card (which sound card, to start with, and what drivers, and what input electronics...) FFT analysers are also notoriously inaccurate.
But in a way, you are attacking it. And, your claim also does not hold its own in the view of the results obtained with the second generation of RH amps, where RH88 can work in various modes, including triode driver into triode output (triode connected KT88/6550), not to mention the RH300B whre triode drives DHT... not to mention the presumed notoriety...
I suggest you build one for yourself and establish on your own whether it sound nice or not, and test it with sound card FFT analysers and publish your results (by the way, did you publish any results so far?) and than claim whichever notoriety. I have already published schematics, sims, everything... without witholding information. Anyone can insert my schematics with whichever models into some simulation software and do sims on his/her own, to check whether my sims "hold water" if he/her is interested in truth and knowledge.
On the other hand, if this is all about notoriety and pride, I am obviously in the wrong place.
Focused closer, that is what they call it where you live.
Regards,
Alex
To achieve notoriety there has to be common consense about that, and not dismissal of something as simplistic.
No, I have not tested "the real thing" with a sound card FFT, both because I did not need to, and because I did not want to devote my tim to it.
Did not need to means that nothing went horribly wrong in the way the amp works, and I cannot care less whether the distortions are 1% or 2% at 4W. Distortions you can hear, clipping you can hear, and output power you can measure extremely simply.
Further, if tube models are simplistic and notriously inaccurate, one could object that sound card (which sound card, to start with, and what drivers, and what input electronics...) FFT analysers are also notoriously inaccurate.
But in a way, you are attacking it. And, your claim also does not hold its own in the view of the results obtained with the second generation of RH amps, where RH88 can work in various modes, including triode driver into triode output (triode connected KT88/6550), not to mention the RH300B whre triode drives DHT... not to mention the presumed notoriety...
I suggest you build one for yourself and establish on your own whether it sound nice or not, and test it with sound card FFT analysers and publish your results (by the way, did you publish any results so far?) and than claim whichever notoriety. I have already published schematics, sims, everything... without witholding information. Anyone can insert my schematics with whichever models into some simulation software and do sims on his/her own, to check whether my sims "hold water" if he/her is interested in truth and knowledge.
On the other hand, if this is all about notoriety and pride, I am obviously in the wrong place.
Focused closer, that is what they call it where you live.
Regards,
Alex
ABOUT PERFECTION
Yes, people have tried and eventually succeeded in modifying and/or improving the original RH84 in various ways, including a pentode driver instead of a triode driver.
I do not know of any hybridization of the RH concept. I like tubes, like amps being made to last and like to predict possible mishaps and avoid them. You can build an RH84 and used it with a wide variety of B+ voltage without worrying anything (exept extremes, of course). What will differ is the voltage... and you can replace the driver tube with another without worrying that something will break or smoke, but there is no guarantee of the final result in sonic terms.
Finally, nothing in life is perfect and there is always someone better than someone else... or than some concept. At least in one important detail. I have brought the RH concept to a further level with the second generation. The further level is improved simplicity and exploitation of the principle, as well as power. Alas, it is unfeasible for most RH 1st generation amps to be transformed into RH 2nd generation amps... because not everything in life is possible and there are some constraints one has to take care about in a material world governed by physics and similar notorieties
Regards,
Alex
Yes, people have tried and eventually succeeded in modifying and/or improving the original RH84 in various ways, including a pentode driver instead of a triode driver.
I do not know of any hybridization of the RH concept. I like tubes, like amps being made to last and like to predict possible mishaps and avoid them. You can build an RH84 and used it with a wide variety of B+ voltage without worrying anything (exept extremes, of course). What will differ is the voltage... and you can replace the driver tube with another without worrying that something will break or smoke, but there is no guarantee of the final result in sonic terms.
Finally, nothing in life is perfect and there is always someone better than someone else... or than some concept. At least in one important detail. I have brought the RH concept to a further level with the second generation. The further level is improved simplicity and exploitation of the principle, as well as power. Alas, it is unfeasible for most RH 1st generation amps to be transformed into RH 2nd generation amps... because not everything in life is possible and there are some constraints one has to take care about in a material world governed by physics and similar notorieties
Regards,
Alex
Re: ABOUT PERFECTION
I suppose you are suggesting that I now ask you how this second generation is constructed ?
Well, o.k.: What is this second generation RH84 ?
If possible, perhaps disclose the third generation also ?
Serious, I just found a 6N2P en el84 at the bottom of the closet so I will try it with some 50 year old transformer. Seems fun.
Alex Kitic said:
The further level is improved simplicity and exploitation of the principle, as well as power. Alas, it is unfeasible for most RH 1st generation amps to be transformed into RH 2nd generation amps... because not everything in life is possible and there are some constraints one has to take care about in a material world governed by physics and similar notorieties
Regards,
Alex
I suppose you are suggesting that I now ask you how this second generation is constructed ?
Well, o.k.: What is this second generation RH84 ?
If possible, perhaps disclose the third generation also ?
Serious, I just found a 6N2P en el84 at the bottom of the closet so I will try it with some 50 year old transformer. Seems fun.
"No, I have not tested "the real thing" with a sound card FFT, both because I did not need to, and because I did not want to devote my tim to it."
"....and I cannot care less whether the distortions are 1% or 2% at 4W."
I rest my case. No further comment needed.
"On the other hand, if this is all about notoriety and pride, I am obviously in the wrong place.
Focused closer, that is what they call it where you live.
Regards,
Alex"
I believe my comments were fully technically defendable, mudslinging would not serve to further them. Again, no further comment needed. Perhaps we can get back to the business of the thread.
Don
"....and I cannot care less whether the distortions are 1% or 2% at 4W."
I rest my case. No further comment needed.
"On the other hand, if this is all about notoriety and pride, I am obviously in the wrong place.
Focused closer, that is what they call it where you live.
Regards,
Alex"
I believe my comments were fully technically defendable, mudslinging would not serve to further them. Again, no further comment needed. Perhaps we can get back to the business of the thread.
Don
YES, for the fun of it!
Try searching other threads, you might find something about RH84 and some answers to your questions. Further, you have not taken the time to do your homework, try my site as well...
Come on, be serious?! How old are you, kindergarden?
THE FUN STARTS WHEN YOU UNDERSTAND THAT IT MIGHT HAVE SAVED YOU A LOT OF MONEY AND TIME
Try searching other threads, you might find something about RH84 and some answers to your questions. Further, you have not taken the time to do your homework, try my site as well...
Come on, be serious?! How old are you, kindergarden?
THE FUN STARTS WHEN YOU UNDERSTAND THAT IT MIGHT HAVE SAVED YOU A LOT OF MONEY AND TIME
THE BUSINESS OF THE THREAD
And I believe the business of the thread is "EL84 - BABY HUEY" -- and various other ideas on how to build alternate PP with EL84 harnessing the plate to plate principle.
Very early in the thread I have tried to contribute with the "double RH84 with phase splitter" concept knowing that it should be what you might call "a winner".
Point is, these forums are mostly visited and consumed by people who have built and will build very few if any amps, listen to music on the PC, know very little physics or whatever, but believe they are "tube scientists" and due to the above have lots of time to devote to a thread on a forum.
Here I really rest my case, there will be no further replies to assumptions. Someone should really try to make an RH84, and even better, make two and combine with a phase splitter of choice to try whether my sim is outrageously off (notoriety, you know) or it was just the fun of it and saved a lot of money and time to listen to someone who knows a lot about what he is talking about.
Regards to all believers.
And I believe the business of the thread is "EL84 - BABY HUEY" -- and various other ideas on how to build alternate PP with EL84 harnessing the plate to plate principle.
Very early in the thread I have tried to contribute with the "double RH84 with phase splitter" concept knowing that it should be what you might call "a winner".
Point is, these forums are mostly visited and consumed by people who have built and will build very few if any amps, listen to music on the PC, know very little physics or whatever, but believe they are "tube scientists" and due to the above have lots of time to devote to a thread on a forum.
Here I really rest my case, there will be no further replies to assumptions. Someone should really try to make an RH84, and even better, make two and combine with a phase splitter of choice to try whether my sim is outrageously off (notoriety, you know) or it was just the fun of it and saved a lot of money and time to listen to someone who knows a lot about what he is talking about.
Regards to all believers.
Gentlemen,
I have not checked the whole long thread nor some others dealing w/ shunt FB if this link into Patrick Turners site into Patrick Turners site was mentioned already, but in any case even a repeated mentioning wouldn´t do harm, I feel.
Regards,
Tom Schlangen
I have not checked the whole long thread nor some others dealing w/ shunt FB if this link into Patrick Turners site into Patrick Turners site was mentioned already, but in any case even a repeated mentioning wouldn´t do harm, I feel.
Regards,
Tom Schlangen