OK, I am new to Tube DIY. I have looked at and re-drawn the schematic from DIYParadise Etude. Am I doing anything stupid with this schematic?
A search for the Etude, has revealed a number of posts, but things still seem rather complicated (at least for me).
I modelled the PSU in PSUDII with a resistive load of 12K and got 293V at B+
The transformer will be the Hammond 274BX with 375-0-375 at 172mA
The chokes will be 30H 595 ohm.
I am trying to understand the circuit, epsecially where the 12K resistor fits-in ie. what does it do?
Anyway, do the voltages look OK, and if not, how can I calculate them, what about current, etc?
Maybe, I should simply be asking - Is there a good reference book for a newbie?????
Charlie
A search for the Etude, has revealed a number of posts, but things still seem rather complicated (at least for me).
I modelled the PSU in PSUDII with a resistive load of 12K and got 293V at B+
The transformer will be the Hammond 274BX with 375-0-375 at 172mA
The chokes will be 30H 595 ohm.
I am trying to understand the circuit, epsecially where the 12K resistor fits-in ie. what does it do?
Anyway, do the voltages look OK, and if not, how can I calculate them, what about current, etc?
Maybe, I should simply be asking - Is there a good reference book for a newbie?????
Charlie
Attachments
Hi Charlie
This is a grounded cathode amplifier. I could try to explain how it works, but you may be better of reading it from John Broskie http://www.tubecad.com/articles_2003/Grounded_Cathode_Amplifier/index.html
The 12k is the load for the tube, not the same as the load on the PSU. In PSUD you can change the load into a constant current. I would do that, and plug in the current drawn through the 12B4 (two times the current if you are building a stereo amp using a common power supply).
Hmm...besides the excellent articles by John Broskie I recommend you to buy Morgan Jones Valve Amplifiers, 3rd edition, available at Amazon. It is a very well written book, packed with schematics, theory, ideas, concepts, etc.
Commercial disclaimer: (Unfortunately) I am not related to him
Erik
This is a grounded cathode amplifier. I could try to explain how it works, but you may be better of reading it from John Broskie http://www.tubecad.com/articles_2003/Grounded_Cathode_Amplifier/index.html
The 12k is the load for the tube, not the same as the load on the PSU. In PSUD you can change the load into a constant current. I would do that, and plug in the current drawn through the 12B4 (two times the current if you are building a stereo amp using a common power supply).
Hmm...besides the excellent articles by John Broskie I recommend you to buy Morgan Jones Valve Amplifiers, 3rd edition, available at Amazon. It is a very well written book, packed with schematics, theory, ideas, concepts, etc.
Commercial disclaimer: (Unfortunately) I am not related to him
Erik
Erik,
Great! I will download/print the article and try to get hold of a copy of the book that you recommend.
I had read before that it is best to use a Constant Current in PSUDII. Now, the specs for the 12B4A state: "plate current = 9.6mA" for Class A amplifier. So for a stereo from a common PSU (ie. two tubes from a single PSU), I would simply use 9.6 X 2 mA for my constant current load????
However, there is a second column of numbers, which states: 34mA for plat current.
OK, a second datasheet states: plate current for grid voltage of -23V = 9.6 mA. But it also states Plate current of 34mA elsewhere.
Hmmmm....maybe the lightbulb is just switching on here. Is this where I use the charts to look up grid voltage and corresponding current-draw???
Given that tubes seem less exacting than other types of components, maybe all the numbers do not need to be exact, but rather within design tolerances.
Thanks,
Charlie
Great! I will download/print the article and try to get hold of a copy of the book that you recommend.
I had read before that it is best to use a Constant Current in PSUDII. Now, the specs for the 12B4A state: "plate current = 9.6mA" for Class A amplifier. So for a stereo from a common PSU (ie. two tubes from a single PSU), I would simply use 9.6 X 2 mA for my constant current load????
However, there is a second column of numbers, which states: 34mA for plat current.
OK, a second datasheet states: plate current for grid voltage of -23V = 9.6 mA. But it also states Plate current of 34mA elsewhere.
Hmmmm....maybe the lightbulb is just switching on here. Is this where I use the charts to look up grid voltage and corresponding current-draw???
Given that tubes seem less exacting than other types of components, maybe all the numbers do not need to be exact, but rather within design tolerances.
Thanks,
Charlie
Charlie,
I hate to be the one to talk negative here but there are far better line stages to build than this one from the diy paradise site. To be perfectly honest it doesn't sound all that good. I built both of the line stages from the paradise site. It sounds ok as does the 5687 but that's about it.
I would highly suggest building an Aikido line stage. It will cost about the same amount of money when you figure you won't need the chokes with the Aikido. Also, a plus here is that all the power supply design work has been done. There are pages of information on the construction of the Aikido here.
I hate to be the one to talk negative here but there are far better line stages to build than this one from the diy paradise site. To be perfectly honest it doesn't sound all that good. I built both of the line stages from the paradise site. It sounds ok as does the 5687 but that's about it.
I would highly suggest building an Aikido line stage. It will cost about the same amount of money when you figure you won't need the chokes with the Aikido. Also, a plus here is that all the power supply design work has been done. There are pages of information on the construction of the Aikido here.
I have looked at the Aikido. It certainly seems that folk really like it.
Still, the artcicle by John Broskie doesn't include a PSU. The posts in the forum seem pretty mixed with regards to recommendations about the PSU - some are very complex.
Of course, I would still have to decide what kind of tubes to use. I know that you suggested the 6FQ7 and the 5687, although I would prefer less gain. I would also still need a suitable transformer, and would this be followed by some kind of rectifier / filter?
I have found the printed circuit boards for sale. Would point-to-point be better sounding?
As always, questions, questions, questions......I really am a newbie at this
Charlie
Still, the artcicle by John Broskie doesn't include a PSU. The posts in the forum seem pretty mixed with regards to recommendations about the PSU - some are very complex.
Of course, I would still have to decide what kind of tubes to use. I know that you suggested the 6FQ7 and the 5687, although I would prefer less gain. I would also still need a suitable transformer, and would this be followed by some kind of rectifier / filter?
I have found the printed circuit boards for sale. Would point-to-point be better sounding?
As always, questions, questions, questions......I really am a newbie at this
Charlie
Charlie,
If I may... I built a 6sn7/6sn7 Aikido hand wired. I've also built the Aikido's using the Diyaudio boards and John Broskie's board.
The Aikido is a superior sounding line stage.
There are numerous pages that would show different tubes and the gain. There are people on this forum like SY that enjoy helping/teaching others. The power supply will not be a problem.
Go for the stars and pick a combo that will give you the gain you want and then ask for help. You will receive it.
I'm not saying the 12B4 line stage is bad. Heck I have one sitting on my shelf in the garage. I will tell you that for the money invested you will be further ahead with the Aikido. I have a number of line stages sitting on my shelves. There are others that would enjoy making only one good line stage.
I would suggest going thru all of the Aikido threads and taking notes or printing them off. Do the research and make up your mind before going further.
I would be interested in knowing what you have for speakers and amplification.
If I may... I built a 6sn7/6sn7 Aikido hand wired. I've also built the Aikido's using the Diyaudio boards and John Broskie's board.
The Aikido is a superior sounding line stage.
There are numerous pages that would show different tubes and the gain. There are people on this forum like SY that enjoy helping/teaching others. The power supply will not be a problem.
Go for the stars and pick a combo that will give you the gain you want and then ask for help. You will receive it.
I'm not saying the 12B4 line stage is bad. Heck I have one sitting on my shelf in the garage. I will tell you that for the money invested you will be further ahead with the Aikido. I have a number of line stages sitting on my shelves. There are others that would enjoy making only one good line stage.
I would suggest going thru all of the Aikido threads and taking notes or printing them off. Do the research and make up your mind before going further.
I would be interested in knowing what you have for speakers and amplification.
cbutterworth said:
Here's an article that explains the basics of setting tube operating parameters:
http://members.aol.com/sbench102/po-dis.html
Second the recommendations on Jones and Broskie. Add Steve Benchs' site to that and you've got enough source material to take you a long way (coming from a fellow neophyte).
Sheldon
cbutterworth said:
You will design your amplifier to have a specific DC operating point (plate voltage, current). Since you have to specify the voltage and current for the amp, it's easiest to just plug in the desired current as a Constant Current load in PSUD and then adjust power supply components (resistors, diodes, inductors, caps, transformer, etc.) to give you the correct voltage and desired ripple characteristics. PSUD also allows you to use the step function to check for ringing when the load changes quickly (as during large music transients).
Sheldon
Burned Fingers,
I emailed John Broskie about the boards. Based on his reply, I have settled for 6SN7 for all four tubes (at present). He actually suggested that 12sn7's were cheaper, but I cannot find any available. He also suggested that I consider the 6DJ8 as a pair to go with two 6SN7.
So, I have pondered the power supply, and will go with around 220V using a Hammond 272BX 250-0-250 going into a 5U4GB, going into two 12H 155 ohm chokes, using 50uF caps.
I'll post the schematic and see what comments I get for the PSU, such as whether, I would really need two chokes, etc.
For my other equipment, I have an AKSA 55N amplifier (www.aksaonline.com); Polk rt600i speakers; and a new Rega Apollo CD-player. Currently, I am using a homebrew passive preamp with Elma source selector and 50K Alps pot in shunt mode.
My next big upgrade will be speakers, as the Polks are definately the weak link in the system. I may buy new speakers such as Vandersteens, or build my own (GR-Research, Selah, etc.).
When I build the Aikido, I'll install and new 100K stepped volume control, either from Glassware Audio Design, or somewhere else.
Anyway, I'd appreciate you ideas.
Charlie
I emailed John Broskie about the boards. Based on his reply, I have settled for 6SN7 for all four tubes (at present). He actually suggested that 12sn7's were cheaper, but I cannot find any available. He also suggested that I consider the 6DJ8 as a pair to go with two 6SN7.
So, I have pondered the power supply, and will go with around 220V using a Hammond 272BX 250-0-250 going into a 5U4GB, going into two 12H 155 ohm chokes, using 50uF caps.
I'll post the schematic and see what comments I get for the PSU, such as whether, I would really need two chokes, etc.
For my other equipment, I have an AKSA 55N amplifier (www.aksaonline.com); Polk rt600i speakers; and a new Rega Apollo CD-player. Currently, I am using a homebrew passive preamp with Elma source selector and 50K Alps pot in shunt mode.
My next big upgrade will be speakers, as the Polks are definately the weak link in the system. I may buy new speakers such as Vandersteens, or build my own (GR-Research, Selah, etc.).
When I build the Aikido, I'll install and new 100K stepped volume control, either from Glassware Audio Design, or somewhere else.
Anyway, I'd appreciate you ideas.
Charlie
A friend of mine has built a number of tube line amps, some his own designs and some other peoples. The most disappointing one he has tried was a 12B4A. He has 2 Aikidos - one hardwired and one with a board. They are both stunning - in a class of their own - but there is no question that hardwired one sounds a bit better. He is using 6N1P for 1st stage and 5687 for second. Hope this helps.
William.
William.
It is a cathode follower. He built it as kindly suggested to me some time ago by Brett on this forum. He did all the homework and came to the conclusion that Brett had got his operating prameters exactly right and felt it ought to be a good little project. If you do a search for a thread titled simpl(ish) 6N1P design, you will find it.
I have listened to it myself. My friend has a pair of "to die for" SE class A tube power amps (of his own design) and even through, these, the sound is bright lacking in body. I would hate to hear it in a solid state setup. However, there is no accounting for taste. It is interesting thoufh, that I was asked at the time why on earth I should be interested in 6N1P's, and this was suggested instead, but now 6N1P's seem to be pretty popular.
I have listened to it myself. My friend has a pair of "to die for" SE class A tube power amps (of his own design) and even through, these, the sound is bright lacking in body. I would hate to hear it in a solid state setup. However, there is no accounting for taste. It is interesting thoufh, that I was asked at the time why on earth I should be interested in 6N1P's, and this was suggested instead, but now 6N1P's seem to be pretty popular.
hihopes said:
My 12B4A preamp built along the lines of the diyparadise one is NOT bright sounding. The diyparadise is not a cathode follower, it's just a conventional cap coupled triode stage. While there might be better designs out there, I think the design is a good simple project to get started on, and decent enough sounding to me, .. the parts aren't expensive. There's a reason that the 12B4 thread on this forum is miles long.
Have fun.
Whatever you call it, it is the design put forward by Brett as I mentioned. My friend built it exactly as per Brett's design, but was not very happy with it. He subsequently went to a lot of trouble trying to get more out of it, and succeeded to a limited degree. Sure it is clean. Some seem to think it is neutral. I don't. It has too little mids and bass for my taste. I was thinking of building this design myself and I am very grateful he did it and saved me the frustration I would have faced.
If I were about to build a simple tube pre, (and perhaps I will in the not too distant future), I would be more inclined to build the simple 5687 pre from diy paradise, which is adapted from the Audionote M7. Just my .02c worth. Whatever you choose to do, enjoy it.
If I were about to build a simple tube pre, (and perhaps I will in the not too distant future), I would be more inclined to build the simple 5687 pre from diy paradise, which is adapted from the Audionote M7. Just my .02c worth. Whatever you choose to do, enjoy it.
Charlie,
I post here as gingertube and post on the AKSA forum as ginger.
Amongst the amps I run are an AKSA 55+ and one of Hugh's new Lifeforce 55. I'm also familiar with the Polks which are a damn fine little speaker (The original version of my Baby Huey Amp using ECL86 was designed specifically to drive a pair of Polks)
I think you should be prepared to build a couple of line stages. What you are essentially trying to do is to impart a little "tubiness" to your source before it hits the AKSA 55N. That is - add a little second harmonic distortion. That will give some warmth and emotion, something the AKSA reproduces really well (better than any other SS amp I've heard). The AKSA 55N has the detail to show up any and all warts in the line stage and its power supply. I think I would take the advice above which suggest going with the Aikido.
As you incrementally improve your system you may wish to contemplate the N+ mod to the AKSA, It really does take it up another level. If you decide that the philosophy of generating the "sound" you want in the pre/line stage and then use an incredibly nimble, exciting and powerfull SS amp to do the speaker drive then you might want to do the 55N trade in for the Lifeforce 55. It doesn't have the "warmth" of the 55N but its imaging and high frequency smoothness, detail, speed and effortless bass is truely stunning. It does however then rely more heavily on a tube line stage for the warmth and emotional engagement. I use mine with an AKSA GK-1 which as you know is a SS buffer driving the volume control followed by a tube line stage.
I'm putting on my flame proof vest right now but I have to say that the method of tailoring your sound in the pre / line stage (tube) and then using a really good SS amp to drive the speakers is a good, ecconomic way of getting a excellent sound system. Certainlky cheaper than equivalent or near equivalent all tube options. Of course the CAVEAT here is that really good SS Amps are'nt that readily available and I actually shudder as I walk past Audio Stores with some of the latest HT offerings belting out aggressive, edgy horrible sound and wonder how the hell anyone could bear to listen to them for even 10 minutes at a time. But then for the price of an AKSA or a "Baby Huey" build you can have 6 channels of 100W each (3 times the crap twice as loud). I have a number of tube power amps I enjoy more than the AKSA SS Amp on some music selections but the AKSA does the "all things to all men" better than any of them and cost about 2/3 of what the cheapest of my tube power amps cost.
Cheers,
Ian
I post here as gingertube and post on the AKSA forum as ginger.
Amongst the amps I run are an AKSA 55+ and one of Hugh's new Lifeforce 55. I'm also familiar with the Polks which are a damn fine little speaker (The original version of my Baby Huey Amp using ECL86 was designed specifically to drive a pair of Polks)
I think you should be prepared to build a couple of line stages. What you are essentially trying to do is to impart a little "tubiness" to your source before it hits the AKSA 55N. That is - add a little second harmonic distortion. That will give some warmth and emotion, something the AKSA reproduces really well (better than any other SS amp I've heard). The AKSA 55N has the detail to show up any and all warts in the line stage and its power supply. I think I would take the advice above which suggest going with the Aikido.
As you incrementally improve your system you may wish to contemplate the N+ mod to the AKSA, It really does take it up another level. If you decide that the philosophy of generating the "sound" you want in the pre/line stage and then use an incredibly nimble, exciting and powerfull SS amp to do the speaker drive then you might want to do the 55N trade in for the Lifeforce 55. It doesn't have the "warmth" of the 55N but its imaging and high frequency smoothness, detail, speed and effortless bass is truely stunning. It does however then rely more heavily on a tube line stage for the warmth and emotional engagement. I use mine with an AKSA GK-1 which as you know is a SS buffer driving the volume control followed by a tube line stage.
I'm putting on my flame proof vest right now but I have to say that the method of tailoring your sound in the pre / line stage (tube) and then using a really good SS amp to drive the speakers is a good, ecconomic way of getting a excellent sound system. Certainlky cheaper than equivalent or near equivalent all tube options. Of course the CAVEAT here is that really good SS Amps are'nt that readily available and I actually shudder as I walk past Audio Stores with some of the latest HT offerings belting out aggressive, edgy horrible sound and wonder how the hell anyone could bear to listen to them for even 10 minutes at a time. But then for the price of an AKSA or a "Baby Huey" build you can have 6 channels of 100W each (3 times the crap twice as loud). I have a number of tube power amps I enjoy more than the AKSA SS Amp on some music selections but the AKSA does the "all things to all men" better than any of them and cost about 2/3 of what the cheapest of my tube power amps cost.
Cheers,
Ian
Ginger,
Thanks for the detailed reply. I have decided to try to make a low-gain Aikido using Octal tubes, I think that I can use the 12B4's or 6SN7's to give a gain of about X9. I started a thread on this, and will likely buy the PCB from John Broskie, and initially use a constant voltage Heath PSU before I commit to building a dedicated PSU for the Aikido. One problem that I have been having with the Aikido, is the design of the PSU, as ther choices seem to be endless. Maybe I'll end up with a 250V tube rectified supply.
I have not done the N+ upgrade, as I am simply waiting till I can afford the LifeForce modules. I recently upgraded my source. I was using a Toshiba SD-3950 and Art DAC. I thought everything sounded good, but the Toshiba was beginning to die, so I home demo'ed a Music Hall CD25.2 and the Rega Apollo. Both units totally blew my previous sources away. The Apollo sounded absolutely amazing, and now resides permanently in my system. In fact, my whole system now sounds much less analytic and more musical, especially with less complex music.
Anyway, I should post to the Aksa forum about my new source, as my wife and I agonized over whether to buy a CD-player, or multi-disc player, or even go totally digital. Once, we had thought about our music preferences, and our music buying methods, we decided that CD is still the way to go.
Regards,
Charlie
Thanks for the detailed reply. I have decided to try to make a low-gain Aikido using Octal tubes, I think that I can use the 12B4's or 6SN7's to give a gain of about X9. I started a thread on this, and will likely buy the PCB from John Broskie, and initially use a constant voltage Heath PSU before I commit to building a dedicated PSU for the Aikido. One problem that I have been having with the Aikido, is the design of the PSU, as ther choices seem to be endless. Maybe I'll end up with a 250V tube rectified supply.
I have not done the N+ upgrade, as I am simply waiting till I can afford the LifeForce modules. I recently upgraded my source. I was using a Toshiba SD-3950 and Art DAC. I thought everything sounded good, but the Toshiba was beginning to die, so I home demo'ed a Music Hall CD25.2 and the Rega Apollo. Both units totally blew my previous sources away. The Apollo sounded absolutely amazing, and now resides permanently in my system. In fact, my whole system now sounds much less analytic and more musical, especially with less complex music.
Anyway, I should post to the Aksa forum about my new source, as my wife and I agonized over whether to buy a CD-player, or multi-disc player, or even go totally digital. Once, we had thought about our music preferences, and our music buying methods, we decided that CD is still the way to go.
Regards,
Charlie
Charlie,
The Broskie board is a great board and would work fine for you. I think you need to experience the "FUN" of point to point on this Aikido. The 6SN7 would be a good choice here. I have been meaning to send you a copy of my power supply for reference. It may be of some help. If you send me your email again I will scan a copy and send it your way.
The Broskie board is a great board and would work fine for you. I think you need to experience the "FUN" of point to point on this Aikido. The 6SN7 would be a good choice here. I have been meaning to send you a copy of my power supply for reference. It may be of some help. If you send me your email again I will scan a copy and send it your way.
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