Konnichiwa,
The Pentode is wired as Triode. It is a compromise, as the D3a is readily available NOS and sounds good used that way. No readily available true triodes with similar performance are around.
True Pentodes as Drivers have some advantages too, it is really a matter of swings and roundabouts.
Sayonara
Gluca said:
The Pentode is wired as Triode. It is a compromise, as the D3a is readily available NOS and sounds good used that way. No readily available true triodes with similar performance are around.
True Pentodes as Drivers have some advantages too, it is really a matter of swings and roundabouts.
Sayonara
As it is becomming obvious here there are many opinions as to how tube amplifiers should be built. In this case I don't have an opinion because I have not built either of these designs, or anything that resembles either of these designs. I try to avoid getting into any type of "what kind of amplifier should I build" discussion unless I have direct experience with one of the designs.
Since there are more than two amplifier designs in the world, as soon as you recommend a design, you will be outnumbered by people recommending a "better" design.
I have had a few conversations with Jack, as have some of my friends, and we have come to the same conclusion, that he is somewhat "old school" and he is a person of strong opinion. He definitely does not like sand in the audio path, and doesn't like mosfet drive. I do. That does not make either of us, or our designs bad, just different. That gives you guys more circuits to build, and unfortunately (for some) more choices to make.
What is of generally accepted opinion is that his transformers are liked by everybody who uses them. One thing that he told me is that if you only need a single speaker impedance (like 8 ohms) he can wind the transformer with only one secondary. This makes the transformer cheaper, and allows better high frequency response.
Since there are more than two amplifier designs in the world, as soon as you recommend a design, you will be outnumbered by people recommending a "better" design.
I have had a few conversations with Jack, as have some of my friends, and we have come to the same conclusion, that he is somewhat "old school" and he is a person of strong opinion. He definitely does not like sand in the audio path, and doesn't like mosfet drive. I do. That does not make either of us, or our designs bad, just different. That gives you guys more circuits to build, and unfortunately (for some) more choices to make.
What is of generally accepted opinion is that his transformers are liked by everybody who uses them. One thing that he told me is that if you only need a single speaker impedance (like 8 ohms) he can wind the transformer with only one secondary. This makes the transformer cheaper, and allows better high frequency response.
Hi Kofi,
It's interesting to note that Welborne's new DRD based kit amps using Electraprint iron (Terraplane 300B and 45 Starchief) now feature common mode chokes for the filament supplies... So maybe it's just a matter of opinion?
http://www.welbornelabs.com/images/terraschematic.jpg
from Ron Welborne's site:
"Not being able to remove the electrolytic capacitors from the 300B's filament supply without increasing the noise level leaves one looking for other solutions. We are already using Schottky diodes and a CLC power supply in our DRD design which was a phenomenal improvement over the typical CRC supply and even supplies utilizing current source regulators. However I felt the filament supply was still a source, or path, for noise to enter the audio signal. So I decided to add an additional stage of filtering and one in the form of a Common Mode Choke. Through extensive testing I'm now certain this additional choke is effectively filtering the remaining vestiges of electrolytic noise, diode switching noise and rf noise."
It's interesting to note that Welborne's new DRD based kit amps using Electraprint iron (Terraplane 300B and 45 Starchief) now feature common mode chokes for the filament supplies... So maybe it's just a matter of opinion?
http://www.welbornelabs.com/images/terraschematic.jpg
from Ron Welborne's site:
"Not being able to remove the electrolytic capacitors from the 300B's filament supply without increasing the noise level leaves one looking for other solutions. We are already using Schottky diodes and a CLC power supply in our DRD design which was a phenomenal improvement over the typical CRC supply and even supplies utilizing current source regulators. However I felt the filament supply was still a source, or path, for noise to enter the audio signal. So I decided to add an additional stage of filtering and one in the form of a Common Mode Choke. Through extensive testing I'm now certain this additional choke is effectively filtering the remaining vestiges of electrolytic noise, diode switching noise and rf noise."
re: Jack Eliano 300B DRD
My friend had mono blocks made by Jack Elliano himself. I borrowed it and had a listen on my system in my room. One thing i immediately noticed is it sounded quite different from other 300Bs I've heard. It sounded so clean and quiet and leaner, maybe bordering or on the clinical/analytical side. It's not bad per se, but matter of taste for the listener.
Here's the picture of the Jack Eliano 300B DRD (the biggest of the two mono blocks), TS Audio DC 300B (the smaller of the two mono blocks), and the ugly amp in the center was my prototype for a DC'ed 2A3.
My friend had mono blocks made by Jack Elliano himself. I borrowed it and had a listen on my system in my room. One thing i immediately noticed is it sounded quite different from other 300Bs I've heard. It sounded so clean and quiet and leaner, maybe bordering or on the clinical/analytical side. It's not bad per se, but matter of taste for the listener.
Here's the picture of the Jack Eliano 300B DRD (the biggest of the two mono blocks), TS Audio DC 300B (the smaller of the two mono blocks), and the ugly amp in the center was my prototype for a DC'ed 2A3.
An externally hosted image should be here but it was not working when we last tested it.
Tell me about it.
I know it. Thorsten helped me with his phono pre project and I'm very thankful for it. I listen to it every day and love the results.
I believe you, I really do. The last thing in the world I want to do is to start a war here, but I feel like I've already done that. Jeez. I'm really sorry that I've brought this on...
I agree about running it at max dissipation. I was really surprised at how "hot" this is running. 410V across the 300b is kinda pushing it, but Jack maintains that this is the proper voltage to get the lowest possible distortion out of the valve.
I really debated my last post for some time. I knew that it could possibly upset you and the masses, but I thought this would make for a good learning tool for me. I guess that's selfish and maybe I shouldn't have posted Jack's comments, but I thought bringing the differences to the forefront would facilitate a deeper understanding of both topologies and the design philosophies therein. Very sorry if I upset the basket here.
OK-- this is the type of thing I'm talking about. Good information.
This may be due to a misunderstanding on my part. I thought that he had used both sides of the 6N1P simultaneously to get what he felt was the proper amount of mA for the 300B.
Hey-- we have a washing machine! Mrs. Annan operates it all the time to clean my two shirts and pair of pants. Makes sense about the interference, though...
OK-- good news on this.
Good to know. Understood.
Really pushing the "quote" limit here, but there's a reason. Hang on...
So noted.
Agreed. I tried to make this plain in my earlier post, but I failed.
I know that's true.
I'd like to say this: I have had nothing but wonderful experiences here on DIYAudio and I'd like them to continue. It was never my intention to start a war of philosophy where thousands of people die needlessly, but I may have done just that.
I just wanted to understand the difference between the two topologies and I guess what I'm really asking is, what is the difference between the two philosophies?
Talking to Jack for even a few minutes (which is hard on the ears sometimes) yields an understanding that he is an engineer that truly believes in Measurement Über Alles, that is, if it measures good, it is good. That's good until it measures good and sounds bad, which is possible. Just look at measurements for some full-range driver enclosure design and you'll know what I'm talkin' 'bout.
Thorsten-- I believe that your design measures and sounds fantastic. The point of my post was not to pit one against another, although it might make for great reality television. The point was to get at the soul behind topologies and to gain an understanding of both, which may have been a mistake.
Sorry for causing distress.
Yep. That's Jack. And you nailed the crux of the issue!
Good point!
Second verse: same as the first.
Anyway. Hope I didn't cause too much turmoil here. Thanks for putting up with me.
Kofi
Gee Kofi, I'da thought with all the wars and grumpy people you deal with every day, Including our new appointee, that these minor (very minor) conflagrations would'nt even register. Breath in, slowly, slowly. Now breath out, slowly. Repeat, repeat, rinse. Relax it's only audio. Besides, it ain't you. Just read the tag line for diyAudio and calibrate your alarms accordingly.
Sheldon
Sheldon
Konnichiwa,
Yes, if you run the 300B at maximum dissipation you will get lower distortion at high power. When I design Amplifiers I tend to look not neccesarily for minimum distortion at maximum power, but for other parameters, such as the amount and spectrum of distortion at one Watt and below. And I derive my operating points unltimaly from listening combined with traditional analysis.
Well, I am not upset. However, Jack made these comments personally to you, in private. You may have been better off dropping an e-mail with your concerns directly to me and keep the discussion out of the public domain.
I do respect what Jack does and have learnd much from his designs (including the fact that I do not like his approach that much) and I'd hate to be seem badmouthing his stuff.
His original design from VTV used the 6AQ8, sections in parallel and at around 8mA total current....
I think Jack is primarily concerned about technical aspects of performance. This includes quite agressive distortion cancellation between stages to get low THD but higher than average levels of odd order distortion and reduced even order levels, a type of distortion that sounds generally dissonant with music.
I personally try to understand how measured performance correlates with percieved good sound and listen long and hard myself for many fundamental things (like the 350V/60mA/5K Load operating point for the 300B) and often accept that good measurements do not reliably equate to good sound.
For example many years ago I modified my first zero feedback 300B PSE Amplifier from my initial build which used a lot of inverse predistortion for 20W out with low THD. Over time I removed this progressivley and as the THD went up the sound became better. For a short while I was willing to subscribe to "more distortion sounds good" thesis, which I also rejected eventually.
I doubt it measures overly good in the traditional sense, that was not my design goal. As for sound, ask Luis.... ;-)
Sayonara
Kofi Annan said:
Yes, if you run the 300B at maximum dissipation you will get lower distortion at high power. When I design Amplifiers I tend to look not neccesarily for minimum distortion at maximum power, but for other parameters, such as the amount and spectrum of distortion at one Watt and below. And I derive my operating points unltimaly from listening combined with traditional analysis.
Kofi Annan said:
Well, I am not upset. However, Jack made these comments personally to you, in private. You may have been better off dropping an e-mail with your concerns directly to me and keep the discussion out of the public domain.
I do respect what Jack does and have learnd much from his designs (including the fact that I do not like his approach that much) and I'd hate to be seem badmouthing his stuff.
Kofi Annan said:
His original design from VTV used the 6AQ8, sections in parallel and at around 8mA total current....
Kofi Annan said:
I think Jack is primarily concerned about technical aspects of performance. This includes quite agressive distortion cancellation between stages to get low THD but higher than average levels of odd order distortion and reduced even order levels, a type of distortion that sounds generally dissonant with music.
I personally try to understand how measured performance correlates with percieved good sound and listen long and hard myself for many fundamental things (like the 350V/60mA/5K Load operating point for the 300B) and often accept that good measurements do not reliably equate to good sound.
For example many years ago I modified my first zero feedback 300B PSE Amplifier from my initial build which used a lot of inverse predistortion for 20W out with low THD. Over time I removed this progressivley and as the THD went up the sound became better. For a short while I was willing to subscribe to "more distortion sounds good" thesis, which I also rejected eventually.
Kofi Annan said:
I doubt it measures overly good in the traditional sense, that was not my design goal. As for sound, ask Luis.... ;-)
Sayonara
Hi all,
Well there we got it. We ask for a few more items and we have the whole meal including desserts.
Kofi, this discursion is truly a learning tool, at least for me it is and I´m sure for many others too. You haven´t started any war. Indeed what you have done is clarify the origin of two similar circuits and their differences, which is a great thing in itself. I´d hate to see one of my diyaudio heroes not posting anymore. You make the question that eveybody is afraid to ask...please keep doing so.
Besides, it´s great for me to listen to people talk about the stuff that I listen here at home...by the way, talking about how is it sounding...last week I changed the grid stoppers to 100R 1/8W NOS Bradleys...not a big change I thought...yesterday I spend 3 hours listening vinyl, first Mingus, Tijuana Moods: Amazing. Then I got a 1977 recording of Puccini´s Tosca. This is when tenor Jose Carreras was really in shape. It literally brougth tears to my eyes and my girlfriend´s, I´m not kidding. Damn! What will happen when I upgrade my cheeze analog rig?
As for now I have very little doubt that when it comes to 2 stage tube amplification this is a really top notch design. I had the opportunity to listen to some other tube amps on my system since I built this one. Some comercial, some DIY and nothing comes even close. This is not to say that it should be "ultimate" but pretty close when you are talking 2 stage. Of course I´m curios to see how a 3 stage all DHT would sound...but I guess that´s material for a different thread.
Take care,
Luis
Well there we got it. We ask for a few more items and we have the whole meal including desserts.
Kofi, this discursion is truly a learning tool, at least for me it is and I´m sure for many others too. You haven´t started any war. Indeed what you have done is clarify the origin of two similar circuits and their differences, which is a great thing in itself. I´d hate to see one of my diyaudio heroes not posting anymore. You make the question that eveybody is afraid to ask...please keep doing so.
Besides, it´s great for me to listen to people talk about the stuff that I listen here at home...by the way, talking about how is it sounding...last week I changed the grid stoppers to 100R 1/8W NOS Bradleys...not a big change I thought...yesterday I spend 3 hours listening vinyl, first Mingus, Tijuana Moods: Amazing. Then I got a 1977 recording of Puccini´s Tosca. This is when tenor Jose Carreras was really in shape. It literally brougth tears to my eyes and my girlfriend´s, I´m not kidding. Damn! What will happen when I upgrade my cheeze analog rig?
As for now I have very little doubt that when it comes to 2 stage tube amplification this is a really top notch design. I had the opportunity to listen to some other tube amps on my system since I built this one. Some comercial, some DIY and nothing comes even close. This is not to say that it should be "ultimate" but pretty close when you are talking 2 stage. Of course I´m curios to see how a 3 stage all DHT would sound...but I guess that´s material for a different thread.
Take care,
Luis
Sorry for the delayed response. Had a friend in from out of town and we sent our livers on an international journey. Smithwicks, Fosters, Singha, Glenmorangie, Reissdorf, Meister Brau, Pabst Blue Ribbon, Hamms, Schlitz, Cooks, Epicac... that trip through the lower 48 was a doozy.
You'd think that, right? Nope.
What? You mean the stapler throwing, end-around-Congress-recess-appointed, porn star moustached, "strict constructionist", "if you lost ten floors...", international coalition harassing NeoCon guy? He's really good at foosball! Beat Silvio Burlosconi 15-3 during a break in open session last week.
Makes sense.
In talking to Jack, I didn't really think he'd mind making his opinion known. Also, I thought this would be a good public debate, given the design philosophies involved. Jack has sort of designed his amplifier around meeting certain engineering principles (increased power, reduced distortion, e.g.) that may or may not appeal to certain listeners. I subscribe to the "first watt" pronciple as well, so I understand where you're going.
Luis loves the sound. End-user adoration trumps measurement 100% of the time.
Good.
Good news. I generally leave that task to member nations anyway.
Woo! [That's the sound I make when I listen to Mingus] Now I have a decent collection of Mingus on vinyl, but not Tijuana Moods. If you're recommending, I'm buying. I think my favorite is Oh Yeah or maybe Blues and Roots. Or Ah Um.
Gain 30lbs (13.6077711 kilograms), develop an expensive scotch habit. Get yelled at by Mrs. Annan for egregious volume and drunkenness: Hey baby! I'm the Presidinn of the Youu Enn Woo!! Woo hoo!!! Iloveyoubabyyerdabest.....
Me too.
Thanks again for all the advice. I think I may take this to the next level here. Here's my idea: I already have parts for Thorsten's design and I'm getting ready to order more. I may be able to make Jack's design and Thorsten's design, as Sheldon mentioned, then I could do some listening comparisons between the two.
I realize that this is an ambitious project, but I already have oil caps, rectifier tubes and some D3as on the way. If Jack can make me a PSU that can handle both topologies (this would take some convincing of Jack) I could conceivably build them both.
You know, I have plenty of nice things to listen to. I think expanding this project to be an examination of both designs might be fun. Of course, it could also be time-consuming, frustrating and expensive. But hey, I got time and an inclination to engage in costly stupidity, so why not?
Hmmmm....
Kofi
You'd think that, right? Nope.
What? You mean the stapler throwing, end-around-Congress-recess-appointed, porn star moustached, "strict constructionist", "if you lost ten floors...", international coalition harassing NeoCon guy? He's really good at foosball! Beat Silvio Burlosconi 15-3 during a break in open session last week.
Makes sense.
In talking to Jack, I didn't really think he'd mind making his opinion known. Also, I thought this would be a good public debate, given the design philosophies involved. Jack has sort of designed his amplifier around meeting certain engineering principles (increased power, reduced distortion, e.g.) that may or may not appeal to certain listeners. I subscribe to the "first watt" pronciple as well, so I understand where you're going.
Luis loves the sound. End-user adoration trumps measurement 100% of the time.
Good.
Good news. I generally leave that task to member nations anyway.
Woo! [That's the sound I make when I listen to Mingus] Now I have a decent collection of Mingus on vinyl, but not Tijuana Moods. If you're recommending, I'm buying. I think my favorite is Oh Yeah or maybe Blues and Roots. Or Ah Um.
Gain 30lbs (13.6077711 kilograms), develop an expensive scotch habit. Get yelled at by Mrs. Annan for egregious volume and drunkenness: Hey baby! I'm the Presidinn of the Youu Enn Woo!! Woo hoo!!! Iloveyoubabyyerdabest.....
Me too.
Thanks again for all the advice. I think I may take this to the next level here. Here's my idea: I already have parts for Thorsten's design and I'm getting ready to order more. I may be able to make Jack's design and Thorsten's design, as Sheldon mentioned, then I could do some listening comparisons between the two.
I realize that this is an ambitious project, but I already have oil caps, rectifier tubes and some D3as on the way. If Jack can make me a PSU that can handle both topologies (this would take some convincing of Jack) I could conceivably build them both.
You know, I have plenty of nice things to listen to. I think expanding this project to be an examination of both designs might be fun. Of course, it could also be time-consuming, frustrating and expensive. But hey, I got time and an inclination to engage in costly stupidity, so why not?
Hmmmm....
Kofi
Dude, you should add Laphroaig to your repertoire list...soon.
I agree. On the other hand I spent some dought building these babies and I listened to them really critically for a long time. Alas, I tried to fault this MF in several ways...but I just didn´t see any evident weaknesses other than soft clipping at INSANE volume levels.
Run to the store!
Good luck!
Take care,
Luis
Sorry for the really, really delayed response. Been wildly busy and unable to engage in any audio stuff.
Added.
Will do.
So, I've reached a conclusion on this project and I'd like to go full on for Thorsten's design. I've already bought parts for it and I like the idea of not running the 300b and cherry-red maximum plate voltage.
So, here's the question (but you know there will be more, right?):
I need to have the PSU transformer wound since I can't find any transormer with the correct secondaries as detailed in this PSU design. I'd like to have Jack wind it, but there's a chance he may refuse, or at least chew me out for asking. He's a great guy, but he holds fast to his principles, so I'm prepared for a lecture.
That said, if I should draw Jack's ire and not be able to convince him to wind this PSU trafo, are there any other suggestions for transformer winding?
I may be speaculating a bit too much here, but if you've ever talked to Jack you'll probably understand.
A little advice?
Kofi
Added.
Will do.
So, I've reached a conclusion on this project and I'd like to go full on for Thorsten's design. I've already bought parts for it and I like the idea of not running the 300b and cherry-red maximum plate voltage.
So, here's the question (but you know there will be more, right?):
I need to have the PSU transformer wound since I can't find any transormer with the correct secondaries as detailed in this PSU design. I'd like to have Jack wind it, but there's a chance he may refuse, or at least chew me out for asking. He's a great guy, but he holds fast to his principles, so I'm prepared for a lecture.
That said, if I should draw Jack's ire and not be able to convince him to wind this PSU trafo, are there any other suggestions for transformer winding?
I may be speaculating a bit too much here, but if you've ever talked to Jack you'll probably understand.
A little advice?
Kofi
I know he will, but he always makes me feel like I'm betraying my country. I'll get past it.
I'm currently trying to source caps for the audio circuit and I'm not sure where to begin. For reference here's the circuit.
Anyway, see the paralelled 15nF / 220nF / 3.3uF / 50uF combo? What caps should I be looking for here and at what voltage rating? I'm thinking that some flim-n-foil jobs or silver mica should suffice, but don't I need a 1000V rating for these?
Nest, with the 15uF / 1uF / 68nF / 4.7nF combo, same question, only I'm thinking that I can live with a 630V rating for these. But you know, I'm probably wrong about that, as usual.
Also, if you decide to respond (which I would appreciate greatly), can you tell me why I might want one capacitor type over another in these positions?
Thanks again for all the help.
Kofi
If you use motor run caps they are rated in volts AC. For DC use you are safe with 1.4x the AC rating. Most of the motor runs I've seen are rated for either 250VAC or 370VAC. So for DC they would be 350VDC and 518VDC. (I've been told by people who should know that the AC rating could be doubled for DC use but I'm too much of a coward to try it!)
Just allow a margin over your planned B+ of say 30% to 50%.
One other thing- if you go with motor run caps make sure they are motor run not motor start . Motor start caps aren't designed for continuous use. You can find them on that little auction site.
Just allow a margin over your planned B+ of say 30% to 50%.
One other thing- if you go with motor run caps make sure they are motor run not motor start . Motor start caps aren't designed for continuous use. You can find them on that little auction site.
Kofi Annan said:
1000V for the first combo would certainly be more than adequate. I would think that 750V would give you plenty of margin. Most caps can take short term surge voltages that are somewhat higher than their steady state rating. Also, I'm no expert here, but if a manufacturer specifies a rating, you can be pretty sure they they have some margin built in too. You can also put caps in series to double their voltage rating (remember, you will half their capacitance as a series pair), as long as you have load sharing resistors, say a pair of 500k, in parallel with the caps, with the midpoint of the resistors connected with the midpoint of the series caps.
For the second combo, at a current of 100mA you will have a voltage drop of 350 across the caps. So a 450V rating should be plenty. At that, you'd have to exceed 140mA or so to run into problems.
Sheldon
Thanks! Sorry for the delayed appreciation.
Well, I'm still ordering parts and I haven't yet gotten up the courage to call Jack. Gotta do it this week...
Another question:
Can anyone recommend a good preamp for these? I'm currently using a slightly modified Bottlehead Foreplay, but I'd like to upgrade me preamp to go along with the new power amps.
Kofi
Hi Kofi,
You ask about a pre-amp.
On paper, the less you get in between your source and the speaker the better. This amp have enough input sensitivity to allow you to go with a passive attenuator.
You could choose to use a 50K pot instead of the 47K input resistor but having tried all sorts of things with my amps (including pots and active pres) I always got best results with either transformer or autoformer attenuation. No active stuff if you don't need the amplification.
I tried S&B TX102s, Slagle autoformers (intact audio) and currently Tribute autoformers. All of them really good but the Tribute got the edge and that's what I'm using right now.
Good luck and keep us posted. Regards,
Luis
You ask about a pre-amp.
On paper, the less you get in between your source and the speaker the better. This amp have enough input sensitivity to allow you to go with a passive attenuator.
You could choose to use a 50K pot instead of the 47K input resistor but having tried all sorts of things with my amps (including pots and active pres) I always got best results with either transformer or autoformer attenuation. No active stuff if you don't need the amplification.
I tried S&B TX102s, Slagle autoformers (intact audio) and currently Tribute autoformers. All of them really good but the Tribute got the edge and that's what I'm using right now.
Good luck and keep us posted. Regards,
Luis
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