Hi Folks,
I'm looking for advice on what tube power amp/s to build, based on my criteria below. Apologies if this has been covered in a previous thread..... I had a look and didn't find anything.
1. Doesn't need to be a kit, but parts must be readily sourceable;
2. Needs to be constructable by someone with strong physics/electrical engineer experience, but not a valve yoda;
3. Good price/performance ratio.......I don't really know what price I have in mind!
4. Needs to have been successfully made by mere mortals previously so I can ask lazy questions.
5. Needs to work with moderately sensitive speakers (93db);
Thanks for a great resource in DIYAudio......any guidance greatly appreciated.
Cheers, Jake
I'm looking for advice on what tube power amp/s to build, based on my criteria below. Apologies if this has been covered in a previous thread..... I had a look and didn't find anything.
1. Doesn't need to be a kit, but parts must be readily sourceable;
2. Needs to be constructable by someone with strong physics/electrical engineer experience, but not a valve yoda;
3. Good price/performance ratio.......I don't really know what price I have in mind!
4. Needs to have been successfully made by mere mortals previously so I can ask lazy questions.
5. Needs to work with moderately sensitive speakers (93db);
Thanks for a great resource in DIYAudio......any guidance greatly appreciated.
Cheers, Jake
You can't go wrong with an EL84 push pull design.
Search for:
Bevios valley amp
Red light district amp
Baby Huey amp
Search for:
Bevios valley amp
Red light district amp
Baby Huey amp
What about 300B SET? I do agree that it is more pricey than the EL84 but I just love the SET tone (magic).
Ken
Ken
I'll grind my own axe and add "El Cheapo" to the list of possibilities. Any member of the large 6V6 family can be used as "finals", with zero parts value changes. EL84s can be used in the O/P stage by changing the values in the RC bias network.
Jim McShane sells kits of parts for the project. You add a chassis and magnetics. A complete set of power magnetics can be purchased from Allied Electronics. Depending on budget, O/P transformers can be sourced from Edcor or Triode Electronics. TE's Dynaclone Z565 is the gold standard, but may too costly.
Jim McShane sells kits of parts for the project. You add a chassis and magnetics. A complete set of power magnetics can be purchased from Allied Electronics. Depending on budget, O/P transformers can be sourced from Edcor or Triode Electronics. TE's Dynaclone Z565 is the gold standard, but may too costly.
Attachments
Gotta ad George Anderson's Tubelab Simple SE which is easy, less than $500 to build and sounds great. Tubelab can be found near the bottom of the homepage here under vendors. Great support.
The 300B/45 SE and Simple push-pull are also good.
The 300B/45 SE and Simple push-pull are also good.
This is an excellent amplifier if done with Acrosound TO-300 outputs.
Twenty-Watt Amplifier
I have a large amount of the amps made back in the Golden age of audio and these homebrew amps that I built are still a go to push/pull amplifier for me.
Now mind you, I have not used this amp with anything other then vintage tubes. But I tend to believe it would work well with modern tubes as well.
So if you're thinking push/pull, This is the real deal. Built correctly you won't be disappointed. These amps sound very much like my Mcintosh MC40's But the Mcintosh Mc40's only sound as good as these when I run original KT66 tubes in them.
Twenty-Watt Amplifier
I have a large amount of the amps made back in the Golden age of audio and these homebrew amps that I built are still a go to push/pull amplifier for me.
Now mind you, I have not used this amp with anything other then vintage tubes. But I tend to believe it would work well with modern tubes as well.
So if you're thinking push/pull, This is the real deal. Built correctly you won't be disappointed. These amps sound very much like my Mcintosh MC40's But the Mcintosh Mc40's only sound as good as these when I run original KT66 tubes in them.
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Almost every amp people build here meet your criteria. 🙂
You should decide if you want a SET or PP. Either should work w/ your speakers in a 'normal' room at 'moderate' levels. Don't ask about differences between them here, as we don't need yet another PP vs SET thread 😀
For a quick and good amp, I like tubelab SE for a simple to build SET, or Pete Millett's PP driver PCB's for a larger build. W/ pete's boards you still get to design your own amp, but w/in the parameters of the PCB so it's a little easier and success is almost guaranteed.
OTOH if you're an engineer and are experienced w/ a soldering iron, you may want to jump in and build it from scratch, point to point. In that case, pick output tubes, draw up a few load lines, plan a driver stage, and get building. Use anyone's design as a rough outline to get you started.
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Yep, Agreed, there's many ways to skin a cat here. My next amp project is a 300b set. I have most of parts together and stainless steel chassis are getting bent this week. thinking of Getting wood covers made for my outputs too.
I guess main thing here is, Take your time and figure out what's going to work for you.( parts and availability)
By the way, The EL84 amps sound great as well. The Dynaco st35 is a nice sounder and an easy project.
I guess main thing here is, Take your time and figure out what's going to work for you.( parts and availability)
By the way, The EL84 amps sound great as well. The Dynaco st35 is a nice sounder and an easy project.
you can do better
We are quite similar in that I have a strong physics background and took electronics (ex-Navy nuke).
The first amps I built "from scratch" I did on a budget using the schematic from the Conn organ. The design is very simple, it sounds very good, and I used it with both 6V6 and 6L6 amps. As I gained more knowledge, it became obvious that the Conn engineers knew what they were doing. They were obviously well educated; it showed in the design, simple, elegant, and sounded great. I tried other schematics, but kept coming back to the Conn because it sounded better. Eventually, I came up with my own unique design, but I would heartily recommend the Conn to anyone starting out that wants a result they will be happy with.
I'm sure this is going to step on a few toes, but an EL84 is way down on the list of tubes I would recommend. I owned several and tried to like them. They were the worst-sounding amps I had except for a few 6BM8's that I got rid of as fast as they came into my possession. IMO, the 6V6 beats the EL84 all day long for sound quality and high quality NOS can still be found if you get the 12-volt heater version, which are, in my opinion, superior because you can rectify the heater current and eliminate a major source of hum.
Also of consideration is it really doesn't cost any more to build out a 6L6 versus an EL84 or 6V6. The cost doesn't start to climb until you get your power supply voltage significantly over 400 volts, necessitating about 4 times the expense in filter caps. I have built some very fine-sounding amps using the Russian 6P3S in place of 6V6 or EL84 by reducing the power supply voltage to about 360 volts and running enough resistance on the power tube's cathodes to keep the current in a range that wouldn't hurt the output transformers. A friend had asked me to build him out a Dynaco with the EL84 and I told him to keep his circuit boards and just trust me. I made him a much better sounding amp with those tubes using the Dynaco transformers (the ones designed for EL84). The 6P3S are cheap and sound great. They got a bad rep by people comparing them to the 6L6GC. They aren't 6L6GC equivalents, even though they are advertised as such by dishonest tube vendors. Use them right and they sound great, certainly much better than an EL84. I got so many requests for easy good-sounding schematics that I made them on Digi-Key's free schematic designer. Free to anyone who PM's and asks for one. FWIW, many of those old organs from the tube era were better engineered and sounded better than hi-fi from the same era.
We are quite similar in that I have a strong physics background and took electronics (ex-Navy nuke).
The first amps I built "from scratch" I did on a budget using the schematic from the Conn organ. The design is very simple, it sounds very good, and I used it with both 6V6 and 6L6 amps. As I gained more knowledge, it became obvious that the Conn engineers knew what they were doing. They were obviously well educated; it showed in the design, simple, elegant, and sounded great. I tried other schematics, but kept coming back to the Conn because it sounded better. Eventually, I came up with my own unique design, but I would heartily recommend the Conn to anyone starting out that wants a result they will be happy with.
I'm sure this is going to step on a few toes, but an EL84 is way down on the list of tubes I would recommend. I owned several and tried to like them. They were the worst-sounding amps I had except for a few 6BM8's that I got rid of as fast as they came into my possession. IMO, the 6V6 beats the EL84 all day long for sound quality and high quality NOS can still be found if you get the 12-volt heater version, which are, in my opinion, superior because you can rectify the heater current and eliminate a major source of hum.
Also of consideration is it really doesn't cost any more to build out a 6L6 versus an EL84 or 6V6. The cost doesn't start to climb until you get your power supply voltage significantly over 400 volts, necessitating about 4 times the expense in filter caps. I have built some very fine-sounding amps using the Russian 6P3S in place of 6V6 or EL84 by reducing the power supply voltage to about 360 volts and running enough resistance on the power tube's cathodes to keep the current in a range that wouldn't hurt the output transformers. A friend had asked me to build him out a Dynaco with the EL84 and I told him to keep his circuit boards and just trust me. I made him a much better sounding amp with those tubes using the Dynaco transformers (the ones designed for EL84). The 6P3S are cheap and sound great. They got a bad rep by people comparing them to the 6L6GC. They aren't 6L6GC equivalents, even though they are advertised as such by dishonest tube vendors. Use them right and they sound great, certainly much better than an EL84. I got so many requests for easy good-sounding schematics that I made them on Digi-Key's free schematic designer. Free to anyone who PM's and asks for one. FWIW, many of those old organs from the tube era were better engineered and sounded better than hi-fi from the same era.
Well you're one of the very few that doesn't like the EL84. It's a very tried and true tube. Every serious manufacturer out there jumped on that boat by the late 50's. Enough said...............
They jumped on that boat for reasons of economy, not sound quality (obviously).
But, just to be fair, guitarists LOVE the EL84. then again, guitarists love distortion and the EL84 excels at that (check the data sheets)
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I have a technique for rating the quality of tubes. It basically computes the gm per unit area of the cathode at max DC current. High gm per area means the grid is too close to the cathode and suffers from grid wire proximity effects (distortion). (note, for frame grid tubes, the typical numbers come out higher for low dist. examples)
You take the ratio of gm at max DC to max DC current. To get this, you take gm at the datasheet rated current, and compute gm at the max DC current rating:
max gm = rated gm * (max DC current rating/ datasheet current for rated gm) ^.666666
then Qfactor = max gm/max DC current
Most (non frame grid) tubes come out around 80 with this calc. Lower is better.
Some of best tubes:
6LQ6 at 51
6DQ5 at 67
6L6 at 72
6CD6 at 74
300B at 77
Some of the worst tubes:
6BM8 at 162
6BQ5 at 213
6HB6 at 437
One caviot, very fine wire mesh spacing for grid1 will give high gm while minimizing the grid wire proximity effects (so low distortion). Frame grid tubes are the best example. Some tubes like 6BQ5 and 6HB6 may have fairly fine mesh grids, so they don't rate well using this simple minded calc. Conversly, very coarse grid wire-wire spacing rates well with this calc, but actually is poor distortion-wise. So you need to inspect the grid1. Fine mesh gives lower distortion.
You also need to look at the plate curves to see how much they are rounded over in the knees. This was done to remove 2nd harmonic in SE stages. (screen current absorbs the lost plate current in the knees) Not so good for P-P, will give high odd order distortion at large signal level. (unless running in class A mode)
You take the ratio of gm at max DC to max DC current. To get this, you take gm at the datasheet rated current, and compute gm at the max DC current rating:
max gm = rated gm * (max DC current rating/ datasheet current for rated gm) ^.666666
then Qfactor = max gm/max DC current
Most (non frame grid) tubes come out around 80 with this calc. Lower is better.
Some of best tubes:
6LQ6 at 51
6DQ5 at 67
6L6 at 72
6CD6 at 74
300B at 77
Some of the worst tubes:
6BM8 at 162
6BQ5 at 213
6HB6 at 437
One caviot, very fine wire mesh spacing for grid1 will give high gm while minimizing the grid wire proximity effects (so low distortion). Frame grid tubes are the best example. Some tubes like 6BQ5 and 6HB6 may have fairly fine mesh grids, so they don't rate well using this simple minded calc. Conversly, very coarse grid wire-wire spacing rates well with this calc, but actually is poor distortion-wise. So you need to inspect the grid1. Fine mesh gives lower distortion.
You also need to look at the plate curves to see how much they are rounded over in the knees. This was done to remove 2nd harmonic in SE stages. (screen current absorbs the lost plate current in the knees) Not so good for P-P, will give high odd order distortion at large signal level. (unless running in class A mode)
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good comeback
Never said 6L6GCs are the best. I tend to think in terms of economy, how to get the best sound for the least amount of money. What constitutes a GOOD audio tube is a complex question. But, to make it simple for you, if you don't have decent bass response, you don't have an audiophile system, so pack it in and go home. The reason is very obvious to sound engineers. ALL instruments, including the cymbals on the drum sets, have their base (resonant) frequency solidly in the range handled by the bass driver, like 150 Hertz and below. If the bass is distorted, it will never sound right. A person with a real audiophile system can prove this to himself with the use of tone controls.
The EL84 is always going to be a joke as an audio tube. It lacks power and it has 10% distortion. People like it because it is so easy to drive. It was made to be a CHEAP audio tube, cheap to manufacture, and CHEAP to implement (because it is easy to drive) and that is all that accounts for its ubiquitous usage, much like the 12a_7 line of tubes. Testing with ears and sophisticated testing equipment proves the 12a_7 line inferior, and yet they are still widely used and will continue to be widely used.
If one wants to forget cost and get a decent audio tube, the EL34 and the GU50 would probably be the logical choices. I have compared the GU50 with the 6550 and the GU50 won by a wide margin. What's that say about the "holy grail" of push-pull amps, the KT88? Near as I can tell from my research, not much diff between a 6550 and a KT88.
Max Robinson (Fun with Tubes) has tested the EL34 in comparison to the 6L6GC and the EL34 won across the board.
This argument is reminiscent of the SE crowd and vinyl crowd who insist they are right. I found the most laughable article ever by a guy who built a push-pull amp out of his 300B triodes and admitted it sounded BETTER than his SE amps, and then made some lame excuse for shelving it and going back to SE. As for the worst amp I have ever listened to, it's a toss-up between an EL84 SE and a 6BM8 push-pull. But hey, it's all subjective. If you like your wimpy, distortion-prone, easy to drive, simple to build, EL84's, more power to you. Rock on. I take a more quality-conscious approach wherein the end result is what matters. My goal was always to make systems that sound excellent without breaking the bank. I have more than succeeded.
The main reason I have succeeded is I stopped believing internet gossip and believed what my own tests and experiments proved, as well as rigidly controlled tests by others who don't have the results of their tests predetermined, as in Max's testing of the EL34 and 6L6GC, and the folks who tested the preamp tubes.
Never said 6L6GCs are the best. I tend to think in terms of economy, how to get the best sound for the least amount of money. What constitutes a GOOD audio tube is a complex question. But, to make it simple for you, if you don't have decent bass response, you don't have an audiophile system, so pack it in and go home. The reason is very obvious to sound engineers. ALL instruments, including the cymbals on the drum sets, have their base (resonant) frequency solidly in the range handled by the bass driver, like 150 Hertz and below. If the bass is distorted, it will never sound right. A person with a real audiophile system can prove this to himself with the use of tone controls.
The EL84 is always going to be a joke as an audio tube. It lacks power and it has 10% distortion. People like it because it is so easy to drive. It was made to be a CHEAP audio tube, cheap to manufacture, and CHEAP to implement (because it is easy to drive) and that is all that accounts for its ubiquitous usage, much like the 12a_7 line of tubes. Testing with ears and sophisticated testing equipment proves the 12a_7 line inferior, and yet they are still widely used and will continue to be widely used.
If one wants to forget cost and get a decent audio tube, the EL34 and the GU50 would probably be the logical choices. I have compared the GU50 with the 6550 and the GU50 won by a wide margin. What's that say about the "holy grail" of push-pull amps, the KT88? Near as I can tell from my research, not much diff between a 6550 and a KT88.
Max Robinson (Fun with Tubes) has tested the EL34 in comparison to the 6L6GC and the EL34 won across the board.
This argument is reminiscent of the SE crowd and vinyl crowd who insist they are right. I found the most laughable article ever by a guy who built a push-pull amp out of his 300B triodes and admitted it sounded BETTER than his SE amps, and then made some lame excuse for shelving it and going back to SE. As for the worst amp I have ever listened to, it's a toss-up between an EL84 SE and a 6BM8 push-pull. But hey, it's all subjective. If you like your wimpy, distortion-prone, easy to drive, simple to build, EL84's, more power to you. Rock on. I take a more quality-conscious approach wherein the end result is what matters. My goal was always to make systems that sound excellent without breaking the bank. I have more than succeeded.
The main reason I have succeeded is I stopped believing internet gossip and believed what my own tests and experiments proved, as well as rigidly controlled tests by others who don't have the results of their tests predetermined, as in Max's testing of the EL34 and 6L6GC, and the folks who tested the preamp tubes.
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Wow. You get out much?
I've built many fine sounding amps using 10GK6 (almost an EL84). 5CZ5, 12W6. All of which I would recommend.
I've built many fine sounding amps using 10GK6 (almost an EL84). 5CZ5, 12W6. All of which I would recommend.
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No, but thank you for your concern.
Scott, look at the data sheets. 17 watts max in push pull at 10% distortion (EL84) versus 55 watts max in push pull at less than 2% distortion. Seems a bit of a no-brainer. You need power to make clean bass, you need clean bass to have an audiophile system. The power is in the bass notes. That's as simple as I can make it. And that is why I just moved away from low-power amps. Unless you want to go to the considerable expense of building horn-loaded bass cabinets (HUGE, bulky, expensive, and time-consuming), the more logical approach would be amps capable of doing the job with more conventional loud-speakers. Who among us hasn't noticed how the lower powered amps just fell flat on their faces when you asked them to drive real loudspeakers? Turn up the volume and the sound quality just goes to pieces. Not so with the more powerful amps, Turn them up, and the sound gets better.
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