Hello All,
I apologize to jhstewart9 and to all.
jhstewart9 WAS promoting the idea of using a power transformer to make it safe.
Unfortunately, I made the mistake of only looking at the schematic not his text.
We have some readers who will copy a schematic and do their very best to build it Exactly as in the schematic.
If they start with that schematic and do not read the text, then Ouch!
The schematic does not include the power transformer, it could use a tacked-on piece of paper on the right side, with a transformer symbol on it.
And, the transformer is 115V in, and 120V out.
So, given todays 120V in, you would get 125.2V out, a little higher than the 116V marking on the schematic.
My power mains varies from 117V to 123V.
123V in gives you 128.3V out 10.6% higher than 116V.
Check your mains voltage before proceeding.
And yes, there are many who will ignore any and all safety considerations.
I apologize to jhstewart9 and to all.
jhstewart9 WAS promoting the idea of using a power transformer to make it safe.
Unfortunately, I made the mistake of only looking at the schematic not his text.
We have some readers who will copy a schematic and do their very best to build it Exactly as in the schematic.
If they start with that schematic and do not read the text, then Ouch!
The schematic does not include the power transformer, it could use a tacked-on piece of paper on the right side, with a transformer symbol on it.
And, the transformer is 115V in, and 120V out.
So, given todays 120V in, you would get 125.2V out, a little higher than the 116V marking on the schematic.
My power mains varies from 117V to 123V.
123V in gives you 128.3V out 10.6% higher than 116V.
Check your mains voltage before proceeding.
And yes, there are many who will ignore any and all safety considerations.
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In order to electrocute yourself on that 1kV you have to go Sticking Your Hand Where It Doesn't Belong. With a hot chassis amplifier it can be inadvertent. Any such equipment can be made safe (relatively speaking) with a $17 or $34 Antek transformer depending on whether you need 50 or 100 VA. And you can dispense with that stupid series heater string and just run 6 or 12 volt tubes or a combination thereof. And you get the dual primary voltage to boot.
A problem I see with “souping up” simple designs like this is that you need to know what you’re doing. If you need to keep the screen at 150 volts, you just need to apply 150 volts, not just rely on dumb luck to get you there and not just hoping everything scales. It may make the circuit more complicated, but that is how you get a performance boost. If you want foolproof, you need to stay closer to the data sheet conditions. The reason they recommend 200 volts is so the screen voltage isn’t as critical and a simple dropping resistor from B+ will do. Want to run it to the edge, you need to control things a little better.
What if a higher voltage power transformer was used?
jhstewart9
Understood as designed looking a maybe 3 watts with 215V power transformer. What if a higher voltage power transformer was used?
The data sheet for the 6W6GT shows Max plate voltage at 300V & Max Screen Voltage at 150V. The Design has 195V on plate and 124 on screen. So what if a 230V or 250V power transformer was used in place of the 215 Volt power transformer? Would that get me closer to the 4 watt mark. Sound quality is most important, extra half a watt is nice, challenges and learning how things work hands on is can be purity enjoyable as well.
Regards David
jhstewart9
Understood as designed looking a maybe 3 watts with 215V power transformer. What if a higher voltage power transformer was used?
The data sheet for the 6W6GT shows Max plate voltage at 300V & Max Screen Voltage at 150V. The Design has 195V on plate and 124 on screen. So what if a 230V or 250V power transformer was used in place of the 215 Volt power transformer? Would that get me closer to the 4 watt mark. Sound quality is most important, extra half a watt is nice, challenges and learning how things work hands on is can be purity enjoyable as well.
Regards David
A hot-chassis RADIO is "safe" because you never touch the circuit. Radio waves in, sound waves out, everything goes through wood/plastic.
A hot-chassis AMPIFIER (guitar or hi-fi) is very different. Normally you have input connections which tie to the circuit COMMON. In hot-chassis this is also an arbitrary side of the wall-plug. I have used hi-chassis in "hi-fi" by not touching RCA connections while wall-plug was in. In guitar (another topic) the player is almost invariably touching strings 'grounded' through cord to amplifier Common, and sweating.
Going back on-topic: why 6W6? It is a very fine tube. It will make 3.8 Watts before losses and serve well. It can be over-run with 250V and make 4+ Watts but maybe with short life. It is cheap (in the US/Canada!) but how cheap? 6V6 is not expensive, any new-made 6V6 can make 5+ Watts with decent life. And much less heater consumption.
A hot-chassis AMPIFIER (guitar or hi-fi) is very different. Normally you have input connections which tie to the circuit COMMON. In hot-chassis this is also an arbitrary side of the wall-plug. I have used hi-chassis in "hi-fi" by not touching RCA connections while wall-plug was in. In guitar (another topic) the player is almost invariably touching strings 'grounded' through cord to amplifier Common, and sweating.
Going back on-topic: why 6W6? It is a very fine tube. It will make 3.8 Watts before losses and serve well. It can be over-run with 250V and make 4+ Watts but maybe with short life. It is cheap (in the US/Canada!) but how cheap? 6V6 is not expensive, any new-made 6V6 can make 5+ Watts with decent life. And much less heater consumption.
Wg_ski - Thanks for the feed back understood.
That’s one of the big reasons I am here I want to learn so I know what I am doing. But you are probably correct. I know 0 and just building as all ready designed I should learn a lot- kills the challenge a bit..
The circuit is designed around the “Mini Single ended” uses a 12L6 Max 200V plate and Max 125 volt screen/ the 6W6 is Max 300V plate and Max 150v screen there should be room for the extra watt keeping under max Voltages. -like you suggest maybe later when I know more and can do it correctly..
The 300 volt operating point for the W6 is for TV vertical deflection use, where it doesn’t sit there dissipating full rating at idle with no signal. That’s why you have to keep the screen voltage down, which limits plate current. If you keep the screen voltage down, all that extra heater current compared to the V6 goes to waste. Therefore, the V6 is preferable in SE apps where 300 or more volts is available. In low voltage use, you want that extra current capability in order to make 3 watts on such low B+. In push pull AB use, you can safely use that extra speak current capability since it is not doing it all the time. They will make more watts in push pull than the V6, and do it safely.
The *real* reason for using the W6 is they are dirt cheap. That comes with strengths and weaknesses.
The *real* reason for using the W6 is they are dirt cheap. That comes with strengths and weaknesses.
I am very new at this, I do understand the 6W6 has weaknesses and appreciate your clarification, I am still making assumptions (nice word for guessing). Yes the cost of the 6W6 is relatively inexpensive but continually rising – and will never be produced again therefore the amp may be a obsolete parts donor in the future.
Using the 6W6 in SE with no signal it will be dissipating full rating at idle. Will this reduce tube life?
For my curiosity and trying to learn and understand -
With 12L6 Screen is 125 and plate is 200 so about 60% lower on screen.
With 6W6 Screen is 150 and plate is 300 so about 50% lower on screen.
Keeping within in manufactures maximum design rating parameters -
If plate / screen percentage were narrowed - what would happen to the sound quality? And Life expectancy?
If plate / screen percentage were widened what would happen to the sound quality? And Life expectancy?
I have found very little on SE circuits using the 6W6 and similar tubs (adding to the challenge). Many comments on how good they sound. Originally, I was looking at 240V transformer for power supply. The issue is the Antek 240 V transformer for power supply is only 50VA I believe this will not be adequative.
Two of three circuits I found for the 6W6 are using 215V @ 85VA- so my choice is narrowed down to Antek 230V, 250V @ 100VA. From your advice and others improve on circuit design drop the Idea on extra wattage. I will buy the Antek 230V (maybe a little extra voltage) before it is too late (Done) I will be going overseas. And investigate the circuit design improvements as recommended.
Thankx everyone plan is slowly moving forward.
6W6 has a reputation of being the poor man's 2A3. Supposedly very linear and sweet sounding in simple ckts. The low b+ they run at makes for less scary first time builds. The lower turns ratio on the opt is a bonus.
That said the 6V6 is also a fine tube and more sensible. HiFi is never sensible🙂.
Certainly the gross heater requirements is a minus but two bottles is not that bad at 15W total. And there's something nice with a NOS tube from way back that does not cost an arm and a leg.
That said the 6V6 is also a fine tube and more sensible. HiFi is never sensible🙂.
Certainly the gross heater requirements is a minus but two bottles is not that bad at 15W total. And there's something nice with a NOS tube from way back that does not cost an arm and a leg.
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Triode 6W6 may be a poor man's 2A3, but since it's plate dissipation is half, the max output power is also half. Expect a little less than 2W before clipping. But believe it or not, 2W is amazing with the right tube. I know because that's what I've been living with the last year since I started 'upgrading' my behemoth 8W amp, and time just does not allow me to finish it...
But the 1.5W SE amp I am using, also for watching movies! is simply stunning, tho I admit it does compress slightly when pushed.
But the 1.5W SE amp I am using, also for watching movies! is simply stunning, tho I admit it does compress slightly when pushed.
Attachments
Another ideal is to build the amp according to the schematics using the 12L6. It is an inexpensive tube-$3.
I am committed to 6W6GT based amplifier.
The schematic from what I understand has many issues.
My thoughts on 6W6GT Tube cost
I thought about building this Amp one year ago then the 6W6 was from reputable vender was $3.20 dollars now $3.95. The price will only go up these tubes will never be produced again.
6W6GT - $3.95 = According to data sheet 3.8 watts reality 2 to 3 watts
25L6GT - $6.95 = According to data sheet 3.8 watts reality 2 to 3 watts
6BQ5 - $9.98 = According to data sheet 5.7 watts reality 4 to 5 watts
12AT7 - $10.95
6SN7 - $15.95
Compairing the 6W6GT to 6BQ5
So that puts 6W6 at $0.45 per watt & the 6BQ5 at $0.45 per watt, same cost per-watt. How many watts do you need? The big picture the tubes are not the high dollar part in an amplifier $Transformers.
If you need replace the 6W6 tubes in the near future how much will they cost?
Regards,
David
Mona,
Thanks I have no issue with multiple fuses, I like the Idea of a fuse on the B+ as well I think I may end up playing with the amp in the future to maximize sound quality, My feer is damaging a high dollar part trying to make a minor change ect: extra protection for the transformer seams like a good idea as well.
Best Regards, David
nikon,f
Thought I should add
At the same price as the 12L6 the 6Y6 will provide 3.5 watts in this circuit.
Are you using a 6W6 Triode SE? I don’t even know how to read the charts Yet..
Regards,
David
Yes. But I have UL taps on the OPT so think I will include a switch so I can try triode, UL, and pentode. Triode gives just under 2W and in theory I can get about 4W in pentode.
Filter Choke for 6W6 SE
Filter Choke
Sorry I have been delinquent in my 6W6 build thread (is that what it is called? A thread) I am not an experienced forum guy.
I have been busy selling everything and packing and trying to get all documents prepared for my move overseas, the last two days tried to get back on track as airports are starting to open.
I need to purchase the heavy items before I leave, I have purchased the output transformers and just purchased power transformer-
AnTek - AS-1T230 - 100VA 230V TRANSFORMER - little higher power than the Hammond 261M6 (83VA) that was used in the 12L6/12SN7 mini singe ended circuit design.
Specs. AnTek - AS-1T230 - 100VA 230V TRANSFORMER
Primary Mains impute 115V or 230V at 50Hz or 60Hz
Power 100VA
Secondary Outputs 4x
1st Secondary- 230V @ 0.22A
2nd Secondary - 230V @ 0.22A
3rd Secondary - 6.3V @ 3A
4th Secondary- 6.3V @ 3A
1st Question-
The 12L6/12SN7 mini singe ended circuit design used a Filter Choke (5 H / 150 mA Hammond 158Q) if I use the AnTek - AS-1T230 - 100VA 230V TRANSFORMER with 2X 6W6 & 1 X 6SN7 this will requiring 2 x Amps over the 12L6/12SN7 combination. Is the Filter Choke (5 H / 150 mA Hammond 158Q) adequate?
2nd Question-
Alllensoncanon recommended considering a more efficient CLC filtering in the power supply. I found on line a 6W6 circut using a CRC filtered solid state If I used either the CLC filtering or the CRC filtered would this make the Filter Choke not necessary?
Filter Choke
Sorry I have been delinquent in my 6W6 build thread (is that what it is called? A thread) I am not an experienced forum guy.
I have been busy selling everything and packing and trying to get all documents prepared for my move overseas, the last two days tried to get back on track as airports are starting to open.
I need to purchase the heavy items before I leave, I have purchased the output transformers and just purchased power transformer-
AnTek - AS-1T230 - 100VA 230V TRANSFORMER - little higher power than the Hammond 261M6 (83VA) that was used in the 12L6/12SN7 mini singe ended circuit design.
Specs. AnTek - AS-1T230 - 100VA 230V TRANSFORMER
Primary Mains impute 115V or 230V at 50Hz or 60Hz
Power 100VA
Secondary Outputs 4x
1st Secondary- 230V @ 0.22A
2nd Secondary - 230V @ 0.22A
3rd Secondary - 6.3V @ 3A
4th Secondary- 6.3V @ 3A
1st Question-
The 12L6/12SN7 mini singe ended circuit design used a Filter Choke (5 H / 150 mA Hammond 158Q) if I use the AnTek - AS-1T230 - 100VA 230V TRANSFORMER with 2X 6W6 & 1 X 6SN7 this will requiring 2 x Amps over the 12L6/12SN7 combination. Is the Filter Choke (5 H / 150 mA Hammond 158Q) adequate?
2nd Question-
Alllensoncanon recommended considering a more efficient CLC filtering in the power supply. I found on line a 6W6 circut using a CRC filtered solid state If I used either the CLC filtering or the CRC filtered would this make the Filter Choke not necessary?
I have decent size opts unfortunately no center tap for UL, and I have read 6W6 are not good UL mode.
Do you have the circuit design schematic? I am committed to finishing this if I can get the parts before, I go overseas.
You said your AMP clips at 2 watts, I found an article with a 6W6 / 6Y6 SE The Power supply is CRC filtered solid state, with a large 680 ohm resister. The article stated the power supply has a lot of sag. The output voltage varies greatly with load. The amplifier never ‘clips’ when overdriven, it simply compresses!
