6l6 with the LL2746 can get at least 200Vpp without 1.5 amps of filament... so el34 is out of question... EL84 is too soft.
6k loading for 845 is not good, I didn't draw the lines, but it seems ridiculous.
6k loading for 845 is not good, I didn't draw the lines, but it seems ridiculous.
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you will have less power than with the 811, it is terrible 😉
845 needs 1000V + to sound well, so a 10k is mandatory at this voltage, clearly visible from load lines...
845 needs 1000V + to sound well, so a 10k is mandatory at this voltage, clearly visible from load lines...
It seems beyond strange to balk at filament current. If one is building an 845 amp, presumably filament current isn't top concern.
If I were doing this, I'd do it right with a 10k load, although a good transformer at that ratio/voltage/power level would probably bankrupt me.
It adds up quickly, 6.3 4Amps (DC), then secondary supply .3A 6sl7 + 0.9A = 1.2A for second 6.3 V on the power transfo...
finding a 4A + 1.8A is harder, for stereo it is 1.2Amps of 6.3 Volt wasted, unless you absolutely love the EL34 as a driver....
I contemplated building a 3xEL34 in UL,P-SET, and when I looked into the heater supply of 4.5Amp x2 = 9 amps of 6.3V I stopped the project there, it involved a separate heater transformer of a decent size, very costly, too much weight added, too much space and problems.
if cost is no object then why not a 2x6sn7 then a 300B, then a 845, like the Cary audio
I personally think that the 6l6 with the lundal is going to kick the 300B out of the water..
finding a 4A + 1.8A is harder, for stereo it is 1.2Amps of 6.3 Volt wasted, unless you absolutely love the EL34 as a driver....
I contemplated building a 3xEL34 in UL,P-SET, and when I looked into the heater supply of 4.5Amp x2 = 9 amps of 6.3V I stopped the project there, it involved a separate heater transformer of a decent size, very costly, too much weight added, too much space and problems.
if cost is no object then why not a 2x6sn7 then a 300B, then a 845, like the Cary audio
I personally think that the 6l6 with the lundal is going to kick the 300B out of the water..
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My friends, do not worry. There are many recipes for making a delicious meal, we don't need to be constrained. If I want lots of power with faultless sound then I just reach for my own design and built TGM8 solid state amp. If I want an 845 just like “everybody else” then I would simply buy a Chinese read-made amplifier as for sure they have the ability to build far more cheaply and I can have it soon instead of this DIY journey. No, this is not a problem to worry about.
Instead we like to contemplate the process a little, buy some parts, look at schematics, think about the chassis. It's more fun when we make your own, which means there's no 'right' or 'wrong' way. This is my answer to the question the OP posed - it’s all about enjoying the process whilst we get to play with the big tubes.
There are always lots of opinions and I value them all!
Here's a couple from other spots, about the 845:
Instead we like to contemplate the process a little, buy some parts, look at schematics, think about the chassis. It's more fun when we make your own, which means there's no 'right' or 'wrong' way. This is my answer to the question the OP posed - it’s all about enjoying the process whilst we get to play with the big tubes.
There are always lots of opinions and I value them all!
Here's a couple from other spots, about the 845:
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No need to buy an expensive 845 with 1000+ V power supply and an impossible OT.
Just emulate some cheap low power triode with a TV Sweep tube output:
https://www.diyaudio.com/forums/tub...-schemes-tv-sweeps-disguise.html?#post5464289
You can tube roll just about anything in for the triode. Some $3 and $4 prospects:
Just emulate some cheap low power triode with a TV Sweep tube output:
https://www.diyaudio.com/forums/tub...-schemes-tv-sweeps-disguise.html?#post5464289
You can tube roll just about anything in for the triode. Some $3 and $4 prospects:
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Well perhaps it’s not just the triode curves that we’re after, we want to exhibit that big chassis, with lots of heavy iron, with big impressive glowing tubes, something that makes the room lights dim when we turn it on, something you can’t buy out of a catalogue, it gives a sense of purpose when we want to listen to music - that’s the point 😀
... these are the big tubes, the real deal, it’s not about saving money or minimizing heat or making it easy to carry, we leave that for the sensible projects, It’s about building whatever wild ideas we fancy
... these are the big tubes, the real deal, it’s not about saving money or minimizing heat or making it easy to carry, we leave that for the sensible projects, It’s about building whatever wild ideas we fancy
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My Unity-Coupled amp right next to me has a separate heater transformer for each power tube (because the cathodes independently swing so much voltage and I don't want to violate max Vh-k). I guess to some, extra heater transformers are a no-go while for me it is no biggie.
Bigun , if you like "wild ideas", then the ideas that smoking-amp proposes are much wilder and more creative than pretty much anything else you will see on any forum. If I completely understood this triode emulation scheme I would build it tomorrow.
I disagree that the 845 needs 1KV. On my amp I have 3 HV settings between 750V and 1000V. Once re-biased the sound of the amp is indistinguishable between the settings, only the max power level.
I do run 10K transformers. They did cost a lot of money but I feel it was worth the investment.
Nope...I designed and got done a pair of OPTs for Ale Moglia to work with the 814. About 6K/110mA for 15W @30Hz (undistorted) but 10K is no problem with same or better performance at very reasonable price. You can see them on his website if you look for the 814 amp.
In few words he had issues with HF response with the Lundahls showing a nasty resonance around 17KHz and roll-off around there as well when using the 814 triode mode. For 250 euros + shipping I got them done. Practically the same performance at low frequency and -3 dB somewhere around 40KHz. Of course the cost included also a third party professional test to (legally ) work up 1KV. This was few years ago but the price today would not be much different.....
when you consider the 845, it is important to keep in mind the various quality...
in the best quality you would see Dhaen builds, and in the lowest, some diy and chinese...
Another thing to keep in mind is the importance of going S.E.T or parallel, because the reason is that the big tubes are fabulous harmonics generators, they add what was missing or what the drivers hide in the details, they create that spacious sound.
You just don't want too much of that spacious sound, just enough and retain much fidelity. I had alnico 95db+ 3 ways with second order with my 845 (an average quality one), and to me it was insufficient in some levels, a much humbler PP-EL34 is right now singing with a much humbler setup and more resolution, quite the opposite of the amorous approach of the 845 toward music.
in the best quality you would see Dhaen builds, and in the lowest, some diy and chinese...
Another thing to keep in mind is the importance of going S.E.T or parallel, because the reason is that the big tubes are fabulous harmonics generators, they add what was missing or what the drivers hide in the details, they create that spacious sound.
You just don't want too much of that spacious sound, just enough and retain much fidelity. I had alnico 95db+ 3 ways with second order with my 845 (an average quality one), and to me it was insufficient in some levels, a much humbler PP-EL34 is right now singing with a much humbler setup and more resolution, quite the opposite of the amorous approach of the 845 toward music.
Hello,
One thing that could have an influence is the increase in the energy stored in the caps once you double the dc voltage on the caps compared to what is usual here.
Greetings, eduard
One thing that could have an influence is the increase in the energy stored in the caps once you double the dc voltage on the caps compared to what is usual here.
Greetings, eduard
Well perhaps it’s not just the triode curves that we’re after, we want to exhibit that big chassis, with lots of heavy iron, with big impressive glowing tubes, something that makes the room lights dim when we turn it on, something you can’t buy out of a catalogue, it gives a sense of purpose when we want to listen to music - that’s the point 😀
... these are the big tubes, the real deal, it’s not about saving money or minimizing heat or making it easy to carry, we leave that for the sensible projects, It’s about building whatever wild ideas we fancy
In that case, why not use an 833A? Or how about those ceramic power triodes from Eimac like the 3CX1500C7? https://www.cpii.com/docs/datasheets/213/3CX1500C7-8938.pdf
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now that I had my coffee,
use the 4ohm tap to load with 13k the 845.
the Hammond is going to work this way
use the 4ohm tap to load with 13k the 845.
the Hammond is going to work this way
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dhaen, your amp looks superb!
gabdx, that’s smart thinking 🙂
I should reveal a bit about my psychology - I have a hard time wasting parts if they are in my junk box I like to use them even though I can afford to buy something better. I drive a 10 year old car with dents and dings because it would be a waste to buy a new one whilst this one works even if the cash sits in my hands.
But with toobs, I prefer to use something that is available in current production, so I am considering 845 instead of using SV811 that already have.
And.... I already have Hammond 1629SEA which came to me from a friend at no cost (well, at least it will be in my hands soon, it is waiting for me to pick it up).
kodabmx, those eimac are tempting too!
gabdx, that’s smart thinking 🙂
I should reveal a bit about my psychology - I have a hard time wasting parts if they are in my junk box I like to use them even though I can afford to buy something better. I drive a 10 year old car with dents and dings because it would be a waste to buy a new one whilst this one works even if the cash sits in my hands.
But with toobs, I prefer to use something that is available in current production, so I am considering 845 instead of using SV811 that already have.
And.... I already have Hammond 1629SEA which came to me from a friend at no cost (well, at least it will be in my hands soon, it is waiting for me to pick it up).
kodabmx, those eimac are tempting too!
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