Kuei or Thornsten, whatever.
Maybe you missed one or two of the following points:-
with the DCMB:
a) infinitesimal changes of the signal amplified by the driver stage are transferred to the output valve's control electrodes, as well as the transients
b) this process is the fastest possible, limited only by the tube and component's characteristics
c) no discrimination occurs between the different frequencies involved ( the signal envelope is preserved to a great extent)
d) the driver load resistor satisfies the need of bias of the output tube, without the need of external bias supply, such as the cathode resistor.
e) The one shown in my schematics, of very low value, is a test point to measure the plate current. The fact that there is no cathode resistor improved the damping factor.
f) the number of components is reduced significantly = lower cost (without affecting the sound quality, on the countrary).
g) Simplicity is obvious = less probabilities to make mistakes.
h) In the Simplex, the 6C33C-B is driven by just one valve (the two triodes of the 6SN7GT). The overall gain of the driver uni is about 70; therefore an 85 V peak swing to drive the 6C33 is obtained with less than 0.9 V rms at the input. The 15-16W output is thus obtained with just two valves (one 6SN7 and one 6C33).
i) If a higher bias and a higher swing are needed, the driver load's resistor can be increased proportionally or, alternatively, the plate current of the last section increased. This can be easily done by adjusting the driver's first section bias, with a variable resistor between cathode and ground
j) In any case, the driver's load resistor remains low enough to compensate the Miller effect and preserve the frequency range
Non apparent features:-
k) A local negative feed back can be obtained by connecting together, through a resistor of suitable value, wattage etc. , the anode and grid of the power tube.
l) However, this causes a reduction of the amount of bias ( voltage drop across the load resistor of the driver) due to the opposite current flowing in it, from the power stage supply. It needs then to be restored either by increasing the value of such resistor or the plate current of the driver.
m) If the driver's gain needs to be increased, but not the bias level, and you do not want any feed-back, then you just connect the resistor of paragr.k) to the + of the output tube's PS, instead of the anode.
n) PSU noise cancellation occurs due to the effects of interaction. In the Simplex driver, the amount of reduction reaches 75 % of its original value.
o) small shifts in the power supply voltage ( ... mains) are partially compensated.
p) The circuit has proven to be stable. Once adjusted ( after a normal warning time) the plate currents of the output valves remain the same within a low and acceptable deviation, for long periods.
As I mentioned in one of my articles, if you don't believe me or you don't like the DCMB, stick to your preferred ( and sometimes dusty) circuits.
Ari.
Maybe you missed one or two of the following points:-
with the DCMB:
a) infinitesimal changes of the signal amplified by the driver stage are transferred to the output valve's control electrodes, as well as the transients
b) this process is the fastest possible, limited only by the tube and component's characteristics
c) no discrimination occurs between the different frequencies involved ( the signal envelope is preserved to a great extent)
d) the driver load resistor satisfies the need of bias of the output tube, without the need of external bias supply, such as the cathode resistor.
e) The one shown in my schematics, of very low value, is a test point to measure the plate current. The fact that there is no cathode resistor improved the damping factor.
f) the number of components is reduced significantly = lower cost (without affecting the sound quality, on the countrary).
g) Simplicity is obvious = less probabilities to make mistakes.
h) In the Simplex, the 6C33C-B is driven by just one valve (the two triodes of the 6SN7GT). The overall gain of the driver uni is about 70; therefore an 85 V peak swing to drive the 6C33 is obtained with less than 0.9 V rms at the input. The 15-16W output is thus obtained with just two valves (one 6SN7 and one 6C33).
i) If a higher bias and a higher swing are needed, the driver load's resistor can be increased proportionally or, alternatively, the plate current of the last section increased. This can be easily done by adjusting the driver's first section bias, with a variable resistor between cathode and ground
j) In any case, the driver's load resistor remains low enough to compensate the Miller effect and preserve the frequency range
Non apparent features:-
k) A local negative feed back can be obtained by connecting together, through a resistor of suitable value, wattage etc. , the anode and grid of the power tube.
l) However, this causes a reduction of the amount of bias ( voltage drop across the load resistor of the driver) due to the opposite current flowing in it, from the power stage supply. It needs then to be restored either by increasing the value of such resistor or the plate current of the driver.
m) If the driver's gain needs to be increased, but not the bias level, and you do not want any feed-back, then you just connect the resistor of paragr.k) to the + of the output tube's PS, instead of the anode.
n) PSU noise cancellation occurs due to the effects of interaction. In the Simplex driver, the amount of reduction reaches 75 % of its original value.
o) small shifts in the power supply voltage ( ... mains) are partially compensated.
p) The circuit has proven to be stable. Once adjusted ( after a normal warning time) the plate currents of the output valves remain the same within a low and acceptable deviation, for long periods.
As I mentioned in one of my articles, if you don't believe me or you don't like the DCMB, stick to your preferred ( and sometimes dusty) circuits.
Ari.
Konnichiwa,
I did not. Note that my objections previously stated where:
1) The claim you made that paralell feed contains an additional coupling capacitor over series feed.
2) The more generic claim (which you however have perpetuated here and elsewhere) that direct coupling removed capacitors from the signal (current) path.
Both claim 1 and claim 2 are demonstrably untrue.
DCMB is not an isse to me beyond the basic issues, which apply to many such and similar galvanically (direct) circuits.
Direct Coupling, Series Feed and Parallel feed have been around since the late 1920, so for well over 70 Years and are well understood by anyone as they so charmingly say in patetents "skilled in the art".
I'll save myself a point by comment on your claims and a refutation of those obviously wrong (what you have written reads more like a High End Company advertising sheet than a factual comment on circuit operation anyway), as I never set out to criticise DCMB sepcifically, had I wanted to do so I would have done so when you published your articles (Yes, I have been aware of your publications and also of earier examples of what is fundamentally the same circuit).
I would suggest however that you are reasonably weary from making demonstrably untrue claims in public and from engaging in counterfactual argumentation.
Oh yes, if someone tells you "have you ever thought of this?" consider at least a full analysis of their proposal before you rubbish it. You may find they actually have a point.
Sayonara
ari polisois said:
I did not. Note that my objections previously stated where:
1) The claim you made that paralell feed contains an additional coupling capacitor over series feed.
2) The more generic claim (which you however have perpetuated here and elsewhere) that direct coupling removed capacitors from the signal (current) path.
Both claim 1 and claim 2 are demonstrably untrue.
DCMB is not an isse to me beyond the basic issues, which apply to many such and similar galvanically (direct) circuits.
Direct Coupling, Series Feed and Parallel feed have been around since the late 1920, so for well over 70 Years and are well understood by anyone as they so charmingly say in patetents "skilled in the art".
I'll save myself a point by comment on your claims and a refutation of those obviously wrong (what you have written reads more like a High End Company advertising sheet than a factual comment on circuit operation anyway), as I never set out to criticise DCMB sepcifically, had I wanted to do so I would have done so when you published your articles (Yes, I have been aware of your publications and also of earier examples of what is fundamentally the same circuit).
I would suggest however that you are reasonably weary from making demonstrably untrue claims in public and from engaging in counterfactual argumentation.
Oh yes, if someone tells you "have you ever thought of this?" consider at least a full analysis of their proposal before you rubbish it. You may find they actually have a point.
Sayonara
Konnichiwa,
I do like to exhaust one issue before attending to new ones, thats all.
I appreciate that you with to extoll the virtues of your designes over all others.
To me that has not much attraction, as every design is a set of compromises and I find more use in people stating was sacrificed to get a certain something, so that a balanced view is obtained and others (and myself) can make resonably informed considerations as to what to build, design, try out etc....
There are many ways to skin a cat and the sucess of any of them tend to be more related to the skill of implementation than any actual topology issues....
Sayonara
ari polisois said:
I do like to exhaust one issue before attending to new ones, thats all.
I appreciate that you with to extoll the virtues of your designes over all others.
To me that has not much attraction, as every design is a set of compromises and I find more use in people stating was sacrificed to get a certain something, so that a balanced view is obtained and others (and myself) can make resonably informed considerations as to what to build, design, try out etc....
There are many ways to skin a cat and the sucess of any of them tend to be more related to the skill of implementation than any actual topology issues....
Sayonara
How come this very interesting topic became so annoying the minute you posted a reply?
We were talking about 6c33c SE. And now we're reading stuff that only a few of us understand or care about. It's all about trade-offs.
What's wrong with you?
How many people do you have to **** off before you realize that it's really YOU and not the rest of the world?
Merry Christmas, Thorsten.
We were talking about 6c33c SE. And now we're reading stuff that only a few of us understand or care about. It's all about trade-offs.
What's wrong with you?
How many people do you have to **** off before you realize that it's really YOU and not the rest of the world?
Merry Christmas, Thorsten.
IN COMPLETE AGREEMENT
I feel that I should state my agreement with FrancoB -- the last few times I logged in there was nothing "interesting" to read about 6C33C amps.
While I've gotten my share of beating for being lazy in doing my homework (no hard feelings, but it ended in being accused of a milder sort of nationalism, somehow corrected by an addition in serbo-croat language...) -- I was actually trying to stir the discussion towards an issue that is seldom considered, higher Ra than usual and the rewards and penalties it could bring.
Eventually, I hoped for a digression towards 6336 amp alternatives, etc.
What I got was a short answer, something about "75ohm" impedance -- and from then on, a discussion I was reluctant to follow.
Did I miss something here? Is it possible that noone is interested in higher load impedances, less current-higher voltage... eventual comparison with 6336?
Let me know...
Aleksandar
I feel that I should state my agreement with FrancoB -- the last few times I logged in there was nothing "interesting" to read about 6C33C amps.
While I've gotten my share of beating for being lazy in doing my homework (no hard feelings, but it ended in being accused of a milder sort of nationalism, somehow corrected by an addition in serbo-croat language...) -- I was actually trying to stir the discussion towards an issue that is seldom considered, higher Ra than usual and the rewards and penalties it could bring.
Eventually, I hoped for a digression towards 6336 amp alternatives, etc.
What I got was a short answer, something about "75ohm" impedance -- and from then on, a discussion I was reluctant to follow.
Did I miss something here? Is it possible that noone is interested in higher load impedances, less current-higher voltage... eventual comparison with 6336?
Let me know...
Aleksandar
Konnichiwa,
It did? Funny. What was in my posting that is so annoying?
http://www.diyaudio.com/forums/showthread.php?postid=255430#post255430
Absolutely. So you don't care to understand the tradeoffs inherent in choosing a given circuit over another? Curious.
The same to you.
Sayonara
FrancoB said:
It did? Funny. What was in my posting that is so annoying?
http://www.diyaudio.com/forums/showthread.php?postid=255430#post255430
FrancoB said:
Absolutely. So you don't care to understand the tradeoffs inherent in choosing a given circuit over another? Curious.
FrancoB said:
The same to you.
Sayonara
Re: IN COMPLETE AGREEMENT
Konnichiwa,
Hmmm. Typhically the maximum power from any given triode is delivered if the load is around 2 X Ra. If you increase the load impedance past this you reduce distortion, however somewhere between around 4 - 6 X Rp the returns start deminishing in terms of measured distortion.
I have found with 300B output valve and also some others of the bigger triodes that they usually sound better opertaed at significantly less than the limits of dissipation, voltage and current and equally with higher than tranditional Anode loads. It boils down to around 1/2 Anode Dissipation and twice the typhical load for the given triode.
The 6336 is rather difficult to get hold off, compared to the 6S33. So I would not hold my breath.
Probably not. I find that people turn to the 6S33 as "solution" to the problkem of the comparatively low power available from the sonically much superior DHT's commonly found in SE Amplifiers. As such clearly sonic qualities are not of as high an issue as power output.
Sayonara
Konnichiwa,
Alex Kitic said:
Hmmm. Typhically the maximum power from any given triode is delivered if the load is around 2 X Ra. If you increase the load impedance past this you reduce distortion, however somewhere between around 4 - 6 X Rp the returns start deminishing in terms of measured distortion.
I have found with 300B output valve and also some others of the bigger triodes that they usually sound better opertaed at significantly less than the limits of dissipation, voltage and current and equally with higher than tranditional Anode loads. It boils down to around 1/2 Anode Dissipation and twice the typhical load for the given triode.
Alex Kitic said:
The 6336 is rather difficult to get hold off, compared to the 6S33. So I would not hold my breath.
Alex Kitic said:
Probably not. I find that people turn to the 6S33 as "solution" to the problkem of the comparatively low power available from the sonically much superior DHT's commonly found in SE Amplifiers. As such clearly sonic qualities are not of as high an issue as power output.
Sayonara
Thorsten, you've diverted yet another thread into a personal demonstration of your quite obviously >101-level EE expertise blah blah. It's tiring to engage with you and your ever point-by-point dismissals, insults and superfactuals (shurely they're not "counterfactuals").
Thorsten, I've always enjoyed your "personal demonstrations of your quite obviously >101-level EE expertise"(which, apparently, has become something of a character flaw around here lately). In this particular case, as a proud owner-builder of a 6c33 SE amp, I have to say that I find your views on this subject most interesting. 😉
Regards,
Milan
Regards,
Milan
LOAD IMPEDANCE FOR TRIODES
Yes, it is true that after some 6xRp you start to get deminishing returns -- but the point is what the Rp would be for the tube used at the operating point chosen.
I cannot completely agree on your findings with the 300B output valve, or others -- mainly about the issue "significantly less then limits of dissipation". If we are "playing" with a 45W anode diss. triode, it might be possible to obtain better sound at i.e. 30W dissipation. On the other hand, if the triode has 15W dissipation, at 10W diss. you are throwing away too much, because what you started with was not that big.
From my experience, if output power is needed, and a superior sound as well, the "king" is voltage thru the tube. If we choose a higher (even more than 2x the usual 2xRp -- I believe in 2.5xRp to be the usual -- hence i.e. 5xRp) Ra, the result will immediately be lower distortion, especially 2nd harmonic. Further, in order not to loose too much power, we can go up to the maximum allowed voltage thru the tube, while we stay at a lower current, thus at a lower dissipation rating... if tried, or simulated, what I just offered as an idea can easily be proved, or disproved.
Why I think this issue is relevant when we speak/write about 6C33C-B? Well, the usual way to use such a tube (as a matter of fact, all tubes originally intended for voltage regulation, like 6336, 6080, and similia), no matter what the connection between driver and output tube is (original DC approach by Ari P. or "dusty" cap coupled approach) -- is to go for a low Ra, very high current and relatively low voltage in order not to surpass anode dissipation ratings. In all such cases, the results are what Kuei Yang Wang refers to as "sonically much superior DHT's".
Furthermore, those of you in the "101-level EE espertise" (whatever does that mean, since electronic tubes theory and circuits are not being taught at EE faculties and the like -- unless the persons mentioned are 60-80 years old, and I believe they are not) league most probably recall that the 6C33C has a different max. voltage rating in case the dissipation is below, if I recall correctly, 30W -- something like 450V. After this idea/proposal, I hope that even die-hards will acknowledge to the fact that a different approach to 6C33C circuits is possible, and might give better sonic results.
To put this one step further, if we presume the output power of a 300B (if you ask me, overrated by audiophiles in every sense of the word, especially since NOS WE specimens are outrageously expensive, and Chinese tubes are not in the same league) is perceived like 8W, how much more power do we actually need, and for what purposes?! I personally think that approx. 10W is more than enough for most people -- outrageously high for high-efficiency speaker owners, quite enough for "normal-efficiency speaker owners". What speakers (efficiency) are you people using, if you are running after that last "squishable" Watt?! Or, at what levels do you listen to music?
A fact, that I would like to change, is the absolute sonic superiority of DHTs like 300B, even 211, as compared to 6C33C and the like. I've listened to lots of amps that would get in the mentioned cathegories, and the 6C33C was never a winner. And, I believe that such "myths" can be changed -- but not with the usual approach.
Just a few words about 6336 -- well, I recently got hold of a few... while I do not seem to be able to get any 6C33C... of course, I am talking about gifts and findings, not about "going out there and buying". Just as you can buy some 6C33C, I presume it would not be much of a problem to buy some 6336 (since I did not try that one, I cannot say what the prices would be).
Ari P.'s approach to DC coupling is very interesting indeed, not at all dusty -- after being called "audio designer" on that account, I have done some homework on that, since I immediately found the idea more than just interesting.
But, let us assume someone might go for what I suggest, higher voltage-lower current: the problem to face would be how to get much higher drive voltage output from the driver tube, since my approach would mean a much higher relative -Ug on the output tube. Of course, it is feasible -- I've succesfully simulated a similar driver for an amp with 6AS7s, where relative -Ug would be approx. 130V (feasible both with 5687s and E180CC/5965, just to mention a few. The only issue here, if I am allowed to comment, is the fact that the approach to DC coupling needs some additional control or safety circuitry in order to be what I like to call "idiot proof" -- as compared to the more dusty approach.
One question -- why is there so little mention of simulation results and similia when comparing ideas? What some happily advocate as "101-level EE expertise" should include such things to, or am I wrong?
Thank you all for patiently reading my "pearls of wisdom" (as some like to call it) so far.
Regards,
Aleksandar
Yes, it is true that after some 6xRp you start to get deminishing returns -- but the point is what the Rp would be for the tube used at the operating point chosen.
I cannot completely agree on your findings with the 300B output valve, or others -- mainly about the issue "significantly less then limits of dissipation". If we are "playing" with a 45W anode diss. triode, it might be possible to obtain better sound at i.e. 30W dissipation. On the other hand, if the triode has 15W dissipation, at 10W diss. you are throwing away too much, because what you started with was not that big.
From my experience, if output power is needed, and a superior sound as well, the "king" is voltage thru the tube. If we choose a higher (even more than 2x the usual 2xRp -- I believe in 2.5xRp to be the usual -- hence i.e. 5xRp) Ra, the result will immediately be lower distortion, especially 2nd harmonic. Further, in order not to loose too much power, we can go up to the maximum allowed voltage thru the tube, while we stay at a lower current, thus at a lower dissipation rating... if tried, or simulated, what I just offered as an idea can easily be proved, or disproved.
Why I think this issue is relevant when we speak/write about 6C33C-B? Well, the usual way to use such a tube (as a matter of fact, all tubes originally intended for voltage regulation, like 6336, 6080, and similia), no matter what the connection between driver and output tube is (original DC approach by Ari P. or "dusty" cap coupled approach) -- is to go for a low Ra, very high current and relatively low voltage in order not to surpass anode dissipation ratings. In all such cases, the results are what Kuei Yang Wang refers to as "sonically much superior DHT's".
Furthermore, those of you in the "101-level EE espertise" (whatever does that mean, since electronic tubes theory and circuits are not being taught at EE faculties and the like -- unless the persons mentioned are 60-80 years old, and I believe they are not) league most probably recall that the 6C33C has a different max. voltage rating in case the dissipation is below, if I recall correctly, 30W -- something like 450V. After this idea/proposal, I hope that even die-hards will acknowledge to the fact that a different approach to 6C33C circuits is possible, and might give better sonic results.
To put this one step further, if we presume the output power of a 300B (if you ask me, overrated by audiophiles in every sense of the word, especially since NOS WE specimens are outrageously expensive, and Chinese tubes are not in the same league) is perceived like 8W, how much more power do we actually need, and for what purposes?! I personally think that approx. 10W is more than enough for most people -- outrageously high for high-efficiency speaker owners, quite enough for "normal-efficiency speaker owners". What speakers (efficiency) are you people using, if you are running after that last "squishable" Watt?! Or, at what levels do you listen to music?
A fact, that I would like to change, is the absolute sonic superiority of DHTs like 300B, even 211, as compared to 6C33C and the like. I've listened to lots of amps that would get in the mentioned cathegories, and the 6C33C was never a winner. And, I believe that such "myths" can be changed -- but not with the usual approach.
Just a few words about 6336 -- well, I recently got hold of a few... while I do not seem to be able to get any 6C33C... of course, I am talking about gifts and findings, not about "going out there and buying". Just as you can buy some 6C33C, I presume it would not be much of a problem to buy some 6336 (since I did not try that one, I cannot say what the prices would be).
Ari P.'s approach to DC coupling is very interesting indeed, not at all dusty -- after being called "audio designer" on that account, I have done some homework on that, since I immediately found the idea more than just interesting.
But, let us assume someone might go for what I suggest, higher voltage-lower current: the problem to face would be how to get much higher drive voltage output from the driver tube, since my approach would mean a much higher relative -Ug on the output tube. Of course, it is feasible -- I've succesfully simulated a similar driver for an amp with 6AS7s, where relative -Ug would be approx. 130V (feasible both with 5687s and E180CC/5965, just to mention a few. The only issue here, if I am allowed to comment, is the fact that the approach to DC coupling needs some additional control or safety circuitry in order to be what I like to call "idiot proof" -- as compared to the more dusty approach.
One question -- why is there so little mention of simulation results and similia when comparing ideas? What some happily advocate as "101-level EE expertise" should include such things to, or am I wrong?
Thank you all for patiently reading my "pearls of wisdom" (as some like to call it) so far.
Regards,
Aleksandar
Re: LOAD IMPEDANCE FOR TRIODES
Konnichiwa,
Absolutely. In my case I found the "sweet spot" for the 300B on subjective sonics to be with 350V/60mA where the Ra is around 800R. Out of 2K4/3K6/4K8 I found 4K8 to bet marginally better sounding than 3K6 but either of them was much better than 2K4 (whgich incidentally would be 4 X Rp).
That is what I have found to hold true for EL34, 6550/KT88, EL84, 300B, 2A3 and from work with others on their amplifiers 211 & 845. The observations are pretty consistent, exploit the device near maximum dissipation and the tone becomes hard and to my ears unpleasant.
Hmmm. You mean you do not attain in absolute terms the maximum available power. But is that per se a problem, if you match the amplifier with apropriate speakers?
Allow me corretc, please, it is voltage ACROSS the valve (or tube).
Yes, I do find myself agreeing with the "High & Cold" (meaning high voltage, low current) operation of Valves in most cases (as opposed to JC Morrisons "Low & Hot" (low anode voltage, high current).
Based on the use of most DHT's per manual common is around 4 X Ra.
Examples, the typhical "WE" 300B operation, 350V/80mA/Ra = 625R, Rl = 2K3 which makes it around 4Ra.
I tend to place more emphasis on low 3rd and higher harmonics.
EE101 is electronics 101 or the first module at university. In my days they thought us such basics as Ohm, Kirchoff, Lenz and co, so the very basics of Electrics. My usual reference to EE101 level suggests most basic Electronics, well before we are concerned with such niceties as active components, but rather left at passive AC and DC networs, basic electromagnetics etc.
I find the 300B a good "all round" option, especially when compared to either EL34/6550 wired as triode and/or such Big Transmitter Valves like 211/845. The 300B can still be fairly economically implemented, many options on different price levels (from very cheapto premium) exist for valves, output transformers etc. As a result is is much more likely people will build a good sounding 300B Amplifier than they will do with most other Valves, hence my recommendation.
I use 8" Fieldcoil Drivers on open Baffles, around 96db/1W/1m right now, I rarely ever go below that, speakers with much lower efficiency sound simply "dead feet" to my ears..
Near realistic, meaning rather loud but not extremely so.
Nothing is absolute> Let's just say that the various aqmplifiers I have build or heard elsewhere which used 6S33, 211, 845, EL34, KT88, 6550 and so on failed to get my attention. The classic medium power DHTs (10, 45, 2A3, 300B, PX4, PX25, RE604, AD1 et al) manage to get my attention beautifully. And if something bores I prefer to limit the time spend on it.
Hence I'm perhaps not the best person to give comments on the absolute merits of "the others", as I have never applied as much effort to getting best sound out of these as I did to the others, but my speakers usually get by on anything with at least 2 - 3 Watt and hence high power (any speaker that requires more power is invariably a device that is better described as distortion and compression effect, not as High Fidelity reproducer) is not an issue.
A friend had plenty of problems. It seems the 6336 was never too plentiful and the remaining ones are being brought up in bulk by people running 6AS7 equipped OTL AMplifiers....
I have just done a little quick simulation. I dropped a 6S33 (Sofia - Audiomatica site curves used - single cathode derived Spice Model) into a 300B Amp modeling Circuit (the JE Labs in fact). I assumend 30W Anode dissipation and 400V Anode voltage, a 1K cathode resistor seemed to provide what was needed with 500V +B, giving 73mA Anode current. BTW, Penta Labs 6S33 Datasheet specifies 400V as absolute max under design center values.
The result has around 13W with a 2K4 load (this seemed to maximise undistorted power) for the whole amp.
Driving the grid of the 6S33 with a peak voltage equal to the Bias voltage and trying several effective anode loads gave the following results:
I'd be carefull to do your own more extensive work, my model was knocked up quickly to simply have a "ballpark" sort of result to give an indication where the ball would land.
I do tend to mention my simulation results and my actual measurements where they are done too. However, most people (actually justifiably to a degree) tend not to put much stock into simulations. This largely seems to result from their inability to program their own VERIFIED models and their inability to correctly account for parsitics. So more often then not simulations give misleading results. As a result I also usually get criticised heavily when presenting simulation results (even if they are heavily qualified with disclaimers), so even I rarely bother now.
Also to note, most people (even EE's) do not really understand how the results of measurements (or suimulations) correlate with subjective perception. This again means their results are of limited untility to them and others.
No, not really, it is more EE305 or therabouts, minimum.
Sayonara
Konnichiwa,
Alex Kitic said:
Absolutely. In my case I found the "sweet spot" for the 300B on subjective sonics to be with 350V/60mA where the Ra is around 800R. Out of 2K4/3K6/4K8 I found 4K8 to bet marginally better sounding than 3K6 but either of them was much better than 2K4 (whgich incidentally would be 4 X Rp).
Alex Kitic said:
That is what I have found to hold true for EL34, 6550/KT88, EL84, 300B, 2A3 and from work with others on their amplifiers 211 & 845. The observations are pretty consistent, exploit the device near maximum dissipation and the tone becomes hard and to my ears unpleasant.
Alex Kitic said:
Hmmm. You mean you do not attain in absolute terms the maximum available power. But is that per se a problem, if you match the amplifier with apropriate speakers?
Alex Kitic said:
Allow me corretc, please, it is voltage ACROSS the valve (or tube).
Yes, I do find myself agreeing with the "High & Cold" (meaning high voltage, low current) operation of Valves in most cases (as opposed to JC Morrisons "Low & Hot" (low anode voltage, high current).
Alex Kitic said:
Based on the use of most DHT's per manual common is around 4 X Ra.
Examples, the typhical "WE" 300B operation, 350V/80mA/Ra = 625R, Rl = 2K3 which makes it around 4Ra.
Alex Kitic said:
I tend to place more emphasis on low 3rd and higher harmonics.
Alex Kitic said:
EE101 is electronics 101 or the first module at university. In my days they thought us such basics as Ohm, Kirchoff, Lenz and co, so the very basics of Electrics. My usual reference to EE101 level suggests most basic Electronics, well before we are concerned with such niceties as active components, but rather left at passive AC and DC networs, basic electromagnetics etc.
Alex Kitic said:
I find the 300B a good "all round" option, especially when compared to either EL34/6550 wired as triode and/or such Big Transmitter Valves like 211/845. The 300B can still be fairly economically implemented, many options on different price levels (from very cheapto premium) exist for valves, output transformers etc. As a result is is much more likely people will build a good sounding 300B Amplifier than they will do with most other Valves, hence my recommendation.
Alex Kitic said:
I use 8" Fieldcoil Drivers on open Baffles, around 96db/1W/1m right now, I rarely ever go below that, speakers with much lower efficiency sound simply "dead feet" to my ears..
Alex Kitic said:
Near realistic, meaning rather loud but not extremely so.
Alex Kitic said:
Nothing is absolute> Let's just say that the various aqmplifiers I have build or heard elsewhere which used 6S33, 211, 845, EL34, KT88, 6550 and so on failed to get my attention. The classic medium power DHTs (10, 45, 2A3, 300B, PX4, PX25, RE604, AD1 et al) manage to get my attention beautifully. And if something bores I prefer to limit the time spend on it.
Hence I'm perhaps not the best person to give comments on the absolute merits of "the others", as I have never applied as much effort to getting best sound out of these as I did to the others, but my speakers usually get by on anything with at least 2 - 3 Watt and hence high power (any speaker that requires more power is invariably a device that is better described as distortion and compression effect, not as High Fidelity reproducer) is not an issue.
Alex Kitic said:
A friend had plenty of problems. It seems the 6336 was never too plentiful and the remaining ones are being brought up in bulk by people running 6AS7 equipped OTL AMplifiers....
Alex Kitic said:
I have just done a little quick simulation. I dropped a 6S33 (Sofia - Audiomatica site curves used - single cathode derived Spice Model) into a 300B Amp modeling Circuit (the JE Labs in fact). I assumend 30W Anode dissipation and 400V Anode voltage, a 1K cathode resistor seemed to provide what was needed with 500V +B, giving 73mA Anode current. BTW, Penta Labs 6S33 Datasheet specifies 400V as absolute max under design center values.
The result has around 13W with a 2K4 load (this seemed to maximise undistorted power) for the whole amp.
Driving the grid of the 6S33 with a peak voltage equal to the Bias voltage and trying several effective anode loads gave the following results:
Code:
Zl (R) 2nd 2nd (db) 3rd 3rd (db) Po (W)
3600 2.3% -32.9 0.3% -51.0 10.2
3000 2.8% -31.1 0.2% -55.7 11.7
2400 5.9% -24.6 1.7% -35.4 13.1
1800 12.4% -18.2 4.7% -26.5 13.5I'd be carefull to do your own more extensive work, my model was knocked up quickly to simply have a "ballpark" sort of result to give an indication where the ball would land.
Alex Kitic said:
I do tend to mention my simulation results and my actual measurements where they are done too. However, most people (actually justifiably to a degree) tend not to put much stock into simulations. This largely seems to result from their inability to program their own VERIFIED models and their inability to correctly account for parsitics. So more often then not simulations give misleading results. As a result I also usually get criticised heavily when presenting simulation results (even if they are heavily qualified with disclaimers), so even I rarely bother now.
Also to note, most people (even EE's) do not really understand how the results of measurements (or suimulations) correlate with subjective perception. This again means their results are of limited untility to them and others.
Alex Kitic said:
No, not really, it is more EE305 or therabouts, minimum.
Sayonara
Electronics Stupidity
Thorsten's only giving part of the picture here. By referring to "EE101" in the way he did, he meant to imply that the person to whom he was talking was stupid so far as electronics is concerned. I mean, what's *lower* than EE101? Basketweaving, presumably. Ah, the Thorsten way.
It's just that type of incivility that detracts so unfortunately from what otherwise could be an enjoyable, interesting discussion.
Kuei Yang Wang said:
Thorsten's only giving part of the picture here. By referring to "EE101" in the way he did, he meant to imply that the person to whom he was talking was stupid so far as electronics is concerned. I mean, what's *lower* than EE101? Basketweaving, presumably. Ah, the Thorsten way.
It's just that type of incivility that detracts so unfortunately from what otherwise could be an enjoyable, interesting discussion.
party breaking...
Thank you all for letting me in on what does 101EE... mean. Electronics stupidity or not -- but at least in this thread I feel like intruding on someone's private party.
Kuei Yang Wang, or Thorsten? Then again, who is Thorsten? Who is it that they call "stupid"?! My "friend" Moamps turns to be Milan something...
Maybe it's just me, I'm used to talking to people, not pseudonims -- seeing their face, their eyes. OK, I know this is the "net", everyone could be anyone... but I must say it makes me a little sick.
While exchanging ideas and views is interesting, intruding on other's parties is just bad manners. It happened to me once or twice -- but then again, I was left with the question unanswered: whose bad manners it was, mine or theirs?
Regards to all you buddies.
Aleksandar
Thank you all for letting me in on what does 101EE... mean. Electronics stupidity or not -- but at least in this thread I feel like intruding on someone's private party.
Kuei Yang Wang, or Thorsten? Then again, who is Thorsten? Who is it that they call "stupid"?! My "friend" Moamps turns to be Milan something...
Maybe it's just me, I'm used to talking to people, not pseudonims -- seeing their face, their eyes. OK, I know this is the "net", everyone could be anyone... but I must say it makes me a little sick.
While exchanging ideas and views is interesting, intruding on other's parties is just bad manners. It happened to me once or twice -- but then again, I was left with the question unanswered: whose bad manners it was, mine or theirs?
Regards to all you buddies.
Aleksandar
Re: Electronics Stupidity
Konnichiwa,
I studiously tried to ignore you, but some people just cant take a hint.
When I write about somethings as being EE101 level I could also write "most basic electronics", EE101 is a shorthand for that.
To suggest that someone is ignorant in EE101 is not to call the stupid, if it was most people in the world would be stupid. It may be your definition of stupid, but it aint mine.
When I suggest people should take EE101 I am suggesting that they make false statements that could have been avoided by having some basic clectronics (eg. EE101) knowledge, so I suggest they lack knowledge/education in a specific area.
I know many subjects where I lack even basic knowledge. It does not make stupid I should say.
May I suggest that you once and for all stop putting motivations on my statements of facts and observations?
You may take my writing literally, as written. I say what I mean to say and write what I mean to write.
Take me literal, I have neither time nor inclination to play silly games or for pointless petty bickering...
Now back to an excelent port and sensible conversation with friends and family.
Have a great time, peace, love and light.
Sayonara
Konnichiwa,
I studiously tried to ignore you, but some people just cant take a hint.
When I write about somethings as being EE101 level I could also write "most basic electronics", EE101 is a shorthand for that.
To suggest that someone is ignorant in EE101 is not to call the stupid, if it was most people in the world would be stupid. It may be your definition of stupid, but it aint mine.
When I suggest people should take EE101 I am suggesting that they make false statements that could have been avoided by having some basic clectronics (eg. EE101) knowledge, so I suggest they lack knowledge/education in a specific area.
I know many subjects where I lack even basic knowledge. It does not make stupid I should say.
May I suggest that you once and for all stop putting motivations on my statements of facts and observations?
You may take my writing literally, as written. I say what I mean to say and write what I mean to write.
Take me literal, I have neither time nor inclination to play silly games or for pointless petty bickering...
Now back to an excelent port and sensible conversation with friends and family.
Have a great time, peace, love and light.
Sayonara
6C33C-B load
Dear Aleksander,
You will find attached a list of alternatives, worked by the SE Amp CAD sofware.
The loads are from 200 to 1K.
For each load I selected two alternatives of B+ and quiescent current, except for the 1k load, where you can find 4.
The last line gives you the parameters if you have a power output of 5 W ( for 10 W you need a swing of 55 V peak and the distortion will be H2=4.7 H3=0.2).
The software I used is an old edition and does not optimize automatically. Anyway, this program proved most of the times to be quite realistic.
Take the results as an indication of what happens with a higher load to the power output, distortion, damping factor.
Sorry, but I do not have anything better.
Cheers,
Ari.
Dear Aleksander,
You will find attached a list of alternatives, worked by the SE Amp CAD sofware.
The loads are from 200 to 1K.
For each load I selected two alternatives of B+ and quiescent current, except for the 1k load, where you can find 4.
The last line gives you the parameters if you have a power output of 5 W ( for 10 W you need a swing of 55 V peak and the distortion will be H2=4.7 H3=0.2).
The software I used is an old edition and does not optimize automatically. Anyway, this program proved most of the times to be quite realistic.
Take the results as an indication of what happens with a higher load to the power output, distortion, damping factor.
Sorry, but I do not have anything better.
Cheers,
Ari.
Attachments
Hi,
Alex,
If I were you, I wouldn't worry too much about someone else's "bad" manners.
It most certainly isn't you....
More likely a certain someone with a big axe to grind and not much to say in any way.
Having the nerve to correct another non-native English speaking person on the correct use of that language while hardly capable of typing a single sentence devoid of the obvious plethora of linguistic horrors alone should be telling enough.
Naturally being hidden behind the comfort of a computer makes it all the more easy for the already abrasive to show their true colours.
In the end I'm afraid one just gets used to this....
Fortunately there are still a reasonable number of polite and helpful people around to make the process of acquainting oneself to these places a little less painful.
Regarding the 6336A, I've used that tube myself and while my experience with it were not bad soundwise, whatever small quantities of it that are still around are of rather questionable origin most of the time, leading often to premature failures.
A much better choice, if it were easily available, would be the 6528A (sorry SY). Unfortunately they're hardly common, neither are they cheap.
A tube I always like is the 6080.
I have compared a Megaherz designed SE amp using the 6080 and the AN Baransu (the Japanese Kondo design) on a Lowther system and my wallet immediately told me which one to prefer...
😀
Cheers,😉
Alex,
If I were you, I wouldn't worry too much about someone else's "bad" manners.
It most certainly isn't you....
More likely a certain someone with a big axe to grind and not much to say in any way.
Having the nerve to correct another non-native English speaking person on the correct use of that language while hardly capable of typing a single sentence devoid of the obvious plethora of linguistic horrors alone should be telling enough.
Naturally being hidden behind the comfort of a computer makes it all the more easy for the already abrasive to show their true colours.
In the end I'm afraid one just gets used to this....
Fortunately there are still a reasonable number of polite and helpful people around to make the process of acquainting oneself to these places a little less painful.
Regarding the 6336A, I've used that tube myself and while my experience with it were not bad soundwise, whatever small quantities of it that are still around are of rather questionable origin most of the time, leading often to premature failures.
A much better choice, if it were easily available, would be the 6528A (sorry SY). Unfortunately they're hardly common, neither are they cheap.
A tube I always like is the 6080.
I have compared a Megaherz designed SE amp using the 6080 and the AN Baransu (the Japanese Kondo design) on a Lowther system and my wallet immediately told me which one to prefer...
😀
Cheers,😉
DIFFERENT APPROACH
Ari,
Thank you very much for your time and effort -- still, not what I had in mind. I was not thinking about 1k loads instead of i.e. 600 ohm loads, which all seem very usual and conventional to me.
Actually, I was thinking about 3k and even 5k loads, lower currents, <30W dissipation, etc. Something completely different.
I am attaching a little illustration (from SE CAD) just to show what I had in mind. By reviewing it, you will most probably find the distortion outrageously high (2nd order), but do not consider it as a project, just as an idea. I do not worry that much about 2nd order distortion, because among various solutions, it will be relatively easy to have the driver generate 2nd order distortions (among other reasons due to the high voltage swing needed). The 2nd order distortions will in some measure cancel.
No matter how odd such a proposal (just a guideline) this might seem, I think this approach should be given some attention -- at least, by those who would want to see 6C33C amps sounding different than they usually do (meaning that as I previously said, I still have to hear a 6C33C amp sounding overall "better" than DHT and similia).
A comment about SE CAD -- yes, the results are quite similar to what you will get in practice: but for 6C33C it is supposed you will use both halves of this double triode in parallel... which is not strictly necessary, especially since you can avoid heating both heaters (that might be a further discussion topic).
Regards,
Aleksandar
Ari,
Thank you very much for your time and effort -- still, not what I had in mind. I was not thinking about 1k loads instead of i.e. 600 ohm loads, which all seem very usual and conventional to me.
Actually, I was thinking about 3k and even 5k loads, lower currents, <30W dissipation, etc. Something completely different.
I am attaching a little illustration (from SE CAD) just to show what I had in mind. By reviewing it, you will most probably find the distortion outrageously high (2nd order), but do not consider it as a project, just as an idea. I do not worry that much about 2nd order distortion, because among various solutions, it will be relatively easy to have the driver generate 2nd order distortions (among other reasons due to the high voltage swing needed). The 2nd order distortions will in some measure cancel.
No matter how odd such a proposal (just a guideline) this might seem, I think this approach should be given some attention -- at least, by those who would want to see 6C33C amps sounding different than they usually do (meaning that as I previously said, I still have to hear a 6C33C amp sounding overall "better" than DHT and similia).
A comment about SE CAD -- yes, the results are quite similar to what you will get in practice: but for 6C33C it is supposed you will use both halves of this double triode in parallel... which is not strictly necessary, especially since you can avoid heating both heaters (that might be a further discussion topic).
Regards,
Aleksandar
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