Well apparently I'm a very brave and courageous person because I've built at least ten...
The meaning of courage in building a tube amplifier is to use newer, different circuits. Not to repeat an old circuit for years.
New circuits are often built by amateurs not engineers. They are generally poorly thought out and poorly documented.
They always subjectively sound great but rarely offer any test results to prove it. In reality, there's a lot of spinning of wheels. Folks taken down paths that don't lead anywhere by the false prophets of tube audio.
The schematic i used for this has a complete writeup so that while you're building it you can learn a few things.
I like that. The article was published in radio and television news and authored by Herb Keroes.
While it may be possible for a select few on this forum to design a tube amplifier that performs better than a Williamson, there are very few and I'm not pretending to be one of them.
I for one have the courage to admit that I'll never be half the engineer that Herb Keroes or David Hafler was. It's completely silly to think that their work was misguided and can be improved upon by a bunch of SET amp builders and circuit board populators.
In other words: Take your insults somewhere else...
Were all just trying to have a good time here...
They always subjectively sound great but rarely offer any test results to prove it. In reality, there's a lot of spinning of wheels. Folks taken down paths that don't lead anywhere by the false prophets of tube audio.
The schematic i used for this has a complete writeup so that while you're building it you can learn a few things.
I like that. The article was published in radio and television news and authored by Herb Keroes.
While it may be possible for a select few on this forum to design a tube amplifier that performs better than a Williamson, there are very few and I'm not pretending to be one of them.
I for one have the courage to admit that I'll never be half the engineer that Herb Keroes or David Hafler was. It's completely silly to think that their work was misguided and can be improved upon by a bunch of SET amp builders and circuit board populators.
In other words: Take your insults somewhere else...
Were all just trying to have a good time here...
I guess those power transformers need help. So to avoid replacing them ...
You can use solid state rectifiers which also eliminates the heater power dissipation for the transformer. Some series resistance would reduce the hot switching current, you can make it similar to a 5AR4. With the high B+ dropping like a stone you have idle wear on the tubes and 25 watt performance. If the DCR is high on the choke, reduce the size or simply eliminate it. You can use a solid state regulator for the phase splitter and front end to kill hum.
Agreed on the odd designs. This is a classic that is hard to beat. I simply added housekeeping, like solid state regulators that do help performance. DC heaters for the 6SN7 (in your case), the rest AC.
You can use solid state rectifiers which also eliminates the heater power dissipation for the transformer. Some series resistance would reduce the hot switching current, you can make it similar to a 5AR4. With the high B+ dropping like a stone you have idle wear on the tubes and 25 watt performance. If the DCR is high on the choke, reduce the size or simply eliminate it. You can use a solid state regulator for the phase splitter and front end to kill hum.
Agreed on the odd designs. This is a classic that is hard to beat. I simply added housekeeping, like solid state regulators that do help performance. DC heaters for the 6SN7 (in your case), the rest AC.
The Williamson circuit is actually quite challenging to build, because in many ways it was never really perfected before it was abandoned in the mid-1950's due to the expense and complexity. Even the Keroes circuit discussed here needs some fine tuning to improve it's performance. A proper Williamson is one of the best tube amps I've ever heard. No one manufactures them today, so if you want one, you have to build it yourself. To build it properly, you need to acquire skills with an oscilloscope and the ability to tweak the circuit for best performance. Personally, I've learned a lot over the past five years trying to perfect my own version of it, and I have also enjoyed building variations with different output tubes, output transformers and passive components. It never gets old for me. ;-)
I'm reminded of a recurring character in the Inspector Wallander detective series: a famous painter who only painted one subject--autumn trees in a bog--and spent fifty years trying to get it right. ;-) Nothing wrong with that if it makes you happy!
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The B+ issue is much better now that i pulled my head out of my pooper and set the idle bias of the power tubes to 70 miliamps each instead of 160.
I had usedca .5 ohm resistor where I normally use 1 ohm.
They will not be getting 6550s but el34s run just fine and make a little over 35 watts before clipping.
I'm calling that good enough.
I didn't build these to keep, I built them to pass along once they're reliable, and they're just about to the point of being reliable.
When I was younger, I taught electronics and trained as a technician. I always said that a technician's fear is a brake.
I didn't mean to insult.. Your text is there. See which one is full of insults. Why should you take it the wrong way? I followed the work of a successful designer for years. I wanted to know why others are eager to spend a lot of money on his work? The answer was... this gentleman's great courage. He was not like the others. A collection of tubes circuits with excellent response . The exact reason I entered your post was to discuss the bias of el34.. I wanted to see the opinions of others.
But no one came. Why? Your problem may be something else. I have been here since 2008 and I have followed the law. The forum was created by Australia. Maybe you don't know this and you ordered me to leave here?
I do a fair amount of experimentation but that's not what this thread is about.
We are not discussing opinions on biasing EL34s either. For that info you want facts not opinions.
Facts will be available in the mullard data sheet for EL34.
I was just poking through it myself...
We are not discussing opinions on biasing EL34s either. For that info you want facts not opinions.
Facts will be available in the mullard data sheet for EL34.
I was just poking through it myself...
I don't know. I have always found that a 6CA7 performed better than an EL34. I also hate that EL34 bases run too hot. Neat that you can drop a beam power tube in place of a true pentode.
I'd use a pair of em if I had em.
I bought these with tubes and used those and some I already had to complete 2x working amps.
Next time I'm flush with cash I'll order tubes and get a fresh quad of gold lion kt77s.
For now the old tubes are sounding good enough...
I got the redplate issue fixed up and they're idling at 70 miliamps per tube.
They sound good enough that I may not steal the transformers off of em after all.
Most tube amplifiers have a weak bass response due to the low capacitance of the capacitor after the filter. The beauty of Hi-Fi is the reproduction of the original sound. This is repeated for years and years. Hi-Fi amplifiers are different from guitars amp . The capacitance can be increased even up to220 mfd
I have built this amplifier and I can tell you that the bass response is more than adequate. I recall using more than 10uF there, probably 47uF. In my experience people often go nuts with capacitance in a power supply when it isn't necessary for good response. But Midnightmayhem or anyone else can increase the value of C10, that's not an issue. I'm sure sure how it qualifies as "courage" to change the value of C10, though. ;-)
Hi hooman,
I completely disagree with you on filter capacitance. I never go over 50 uF (47uF is the same thing). Zero issues with bass and most people comment on how well mine work at low frequencies.
The output transformer is the biggest singe component that determines so many characteristics. Mine were designed by Hammond here in Canada, upgraded from the average output transformer by Chris Bacik. Sadly no longer with them.
I completely disagree with you on filter capacitance. I never go over 50 uF (47uF is the same thing). Zero issues with bass and most people comment on how well mine work at low frequencies.
The output transformer is the biggest singe component that determines so many characteristics. Mine were designed by Hammond here in Canada, upgraded from the average output transformer by Chris Bacik. Sadly no longer with them.
Love the Radio and Television News magazine. I have a few, Radio and Popular Electronics too!
I am also a member of Audio Karma. , and there is a similar amplifier , Someone else tried to get results and succeeded.
https://audiokarma.org/forums/index.php?threads/dynaco-a430-homebrew-from-jerry.1048903/
https://audiokarma.org/forums/index.php?threads/dynaco-a430-homebrew-from-jerry.1048903/