I am doing this amp in the coming days.
There is some error insight ?
Resistance values are approximate.
There is some error insight ?
Resistance values are approximate.
Attachments
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Place the 6.8K resistor on the other side of the IT primary with a decoupling capacitor (say 22uF) to ground between the primary and the resistor.
What you've done is made the RP of the driver tube much higher which will result in very poor performance with the IT transformer.
What is the plate resistance of the 6E6P? Is the plate load resistor (6.8K) at least 3x greater?
What you've done is made the RP of the driver tube much higher which will result in very poor performance with the IT transformer.
What is the plate resistance of the 6E6P? Is the plate load resistor (6.8K) at least 3x greater?
Thanks Kevinkr .
The plate resistance of 46 tube like triode is 2380 ohms.
Lundahl said that with a plate resistor under 3k the LL1671 would do a good job.
In case of using the IT like 1: 2 the plate resistance should be 1k max.
Anyway, do you think it is not ideal?
https://www.lundahltransformers.com/wp-content/uploads/datasheets/1671.pdf
The plate resistance of 46 tube like triode is 2380 ohms.
Lundahl said that with a plate resistor under 3k the LL1671 would do a good job.
In case of using the IT like 1: 2 the plate resistance should be 1k max.
Anyway, do you think it is not ideal?
https://www.lundahltransformers.com/wp-content/uploads/datasheets/1671.pdf
The IT is not a good match to the 46 based on what you've just said, the LF will roll off more than an octave early and distortion will be much higher.
6.8K based on 1.2K 6E6P plate resistance should be a good match.
6.8K based on 1.2K 6E6P plate resistance should be a good match.
In your schematic the anode of the first stage is decoupled by a 33uF capacitor. That's not good. The amp will be dead silent (in a bad way...). I think you should skip that capacitor.
Use the 6E6P triode strapped with the 1671/30mA wired as a 1:1. The 46 is giving you gain you probably don't need and it's not as capable of driving the IT as the 6E6P would be.
I am thinking about that.
But this way I need 2v in the input to have 8 watts at the output aprox.
But this way I need 2v in the input to have 8 watts at the output aprox.
Yes, you do. You could use a 1:2 interstage if you need more gain. Is this going to be a power amp or integrated? 2V input sensitivity with a power amp is OK.
Just thinking out loud here.
You could substitute a 6C19 or SV83 as a driver for the interstage, this will cut down on the number of DHT heater supplies you need. You could also try a 6B4G instead of that 45 because it has the same 6.3 heater as the 6E6P you could use the same winding for those.
You could substitute a 6C19 or SV83 as a driver for the interstage, this will cut down on the number of DHT heater supplies you need. You could also try a 6B4G instead of that 45 because it has the same 6.3 heater as the 6E6P you could use the same winding for those.
Attached circuit is using 1:1 IT for 46 and 3k3 OT for 300B. It required 14V-p to drive to full power. For 2V input you'll need at least 14/2=7, say another stage gain of 10 RC coupled will do. It's not quite possible to get 8W with HT400v and 3k3 OT, you need to use a lower Z OT say 1.5K and maybe fixed bias.
Attachments
Have you looked at Ale Moglia's design for 47 into 300b? You could use that. It has a step-up input transformer.
300B SE Amp: 47 Driver – Bartola(R) Valves
I use 46 into 300b with a plate choke on the 46. My solution to extra gain is an op-amp NE5534 stage at the input with x5.5 gain. Same all-DHT concept, different execution.
300B SE Amp: 47 Driver – Bartola(R) Valves
I use 46 into 300b with a plate choke on the 46. My solution to extra gain is an op-amp NE5534 stage at the input with x5.5 gain. Same all-DHT concept, different execution.
Hi Andy.
How are you ?
You know I was watching Ale Moglia's website for weeks.
I wanted to make a 300B amp and I wanted the driver to be an output tube. For that I chose the 6E6PDR, as I believe it is very low noise, 34 gain factor, low anode resistance, high transconductance, and can give many Vpp with minimal distortion. Talking about gain.
Today change the 5-pin socket (46 tube ) for the 4-pin one ( 45 tube ), and the final configuration will be 6E6PDR RC coupling, 45 IT LL1671 (Lundahl advises on the LL1671, that in a 1: 1 configuration the anode resistor of the valve that is connected to the primary does not would have more than 3K, and the 45 I think has only 1.5K anode resistance), and 300B.
This way I think the gain will be more than enough, and I can use an output tube as a driver.
You used an op-amp NE5534. It's probably a better option.
Santiago
How are you ?
You know I was watching Ale Moglia's website for weeks.
I wanted to make a 300B amp and I wanted the driver to be an output tube. For that I chose the 6E6PDR, as I believe it is very low noise, 34 gain factor, low anode resistance, high transconductance, and can give many Vpp with minimal distortion. Talking about gain.
Today change the 5-pin socket (46 tube ) for the 4-pin one ( 45 tube ), and the final configuration will be 6E6PDR RC coupling, 45 IT LL1671 (Lundahl advises on the LL1671, that in a 1: 1 configuration the anode resistor of the valve that is connected to the primary does not would have more than 3K, and the 45 I think has only 1.5K anode resistance), and 300B.
This way I think the gain will be more than enough, and I can use an output tube as a driver.
You used an op-amp NE5534. It's probably a better option.
Santiago
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