I am planning on building a D Lite but wanted to know what some good alternate choices for power transformers would be. I already have a Hammond 273CZ on hand ( 325-0-325v, 150mA ) and a 272HX ( 300-0-300v, 200 mA). I was wondering what my best bet would be? I was afraid of the 273CZ not supplying enough current. It seems like it should be fine with a pair of 6V6's but wanted to double check. I know that I am fine with the 272HX but wanted to know how losing (approximately) 35 volts on the plates would effect the the sound and headroom. Any info or opinions are greatly appreciated.
-Kevin
D Lite Power Transformer
Moderators: pompeiisneaks, Colossal
Re: D Lite Power Transformer
The 273CZ should be fine using 6V6's. The voltage is correct for the dropping string and 150mA is plenty of current. You could also use the 272HX by changing the dropping string to 1k/10k/2k2 and leaving off the 220k to ground.
Re: D Lite Power Transformer
Greetings,
While on the subject of PT, I just looked at General Electric valve specification for 2x 6V6 in AB PP mode, and saw that the maximum signal (plate) current for two valves is 92mA, with maximum signal screen current of 13mA, which means that we would need at least 105mA for that section, which means that 150mA PT is more than sufficient. Those ratings are given for plate voltage of 285V.
Specs. for 2x JJ 6V6S in PP AB class mode, call for 70mA for two tubes and 13mA for max. grid current, which means we would need at least 83mA for that section. That is given for plate voltage of 250V.
Now, one wanders what these numbers are specifically for this particular D'Lite amplifier.
As for the 2x 6L6 in PP AB class mode, I see various numbers, as seen in two different cases:
1. 2x 6L6GC at 360V on the plates, 3k8 Ohm OT primary (load), draws max. signal current of 140mA and max. grid current of 11mA, that is at lest 151mA total (practical situation calls for more current). That arrangement gives Ps sig. max. of 18W.
2. 2x 6L6GC at 450V on the plates, 5k6 Ohm load, draws max. signal current of 210mA (plates) and 22mA (grid), which is a total of at least 232mA that we need (practical situation calls for more). That arrangement gives Ps sig. max. of 55W (!), according to the specs. (Mazda Belvu, specs written in French).
Where does D'Lite fit in this picture? What are we looking at if we use 2x 6V6 and what are we looking at if we 2x 6L6, in numbers (V, Ohm, mA, W)? Any comments by the people that are more ¨up to speed¨, more knowledgeable in this subject, are more than welcome. Can someone do some maths for this particular amp. design we are discussing about?
Particularly as it seems that 150mA at the PT for this purpose is OK for 2x 6V6 output valves, and not OK for 2x 6L6 output valves (rather, in a 200mA, as specified by the suggested kit transformer).
What are we really looking at in terms of specific numbers (in Volts and mA) in those two set-ups (2x6V6 and 2x6L6)?
All the best,
Sven
While on the subject of PT, I just looked at General Electric valve specification for 2x 6V6 in AB PP mode, and saw that the maximum signal (plate) current for two valves is 92mA, with maximum signal screen current of 13mA, which means that we would need at least 105mA for that section, which means that 150mA PT is more than sufficient. Those ratings are given for plate voltage of 285V.
Specs. for 2x JJ 6V6S in PP AB class mode, call for 70mA for two tubes and 13mA for max. grid current, which means we would need at least 83mA for that section. That is given for plate voltage of 250V.
Now, one wanders what these numbers are specifically for this particular D'Lite amplifier.
As for the 2x 6L6 in PP AB class mode, I see various numbers, as seen in two different cases:
1. 2x 6L6GC at 360V on the plates, 3k8 Ohm OT primary (load), draws max. signal current of 140mA and max. grid current of 11mA, that is at lest 151mA total (practical situation calls for more current). That arrangement gives Ps sig. max. of 18W.
2. 2x 6L6GC at 450V on the plates, 5k6 Ohm load, draws max. signal current of 210mA (plates) and 22mA (grid), which is a total of at least 232mA that we need (practical situation calls for more). That arrangement gives Ps sig. max. of 55W (!), according to the specs. (Mazda Belvu, specs written in French).
Where does D'Lite fit in this picture? What are we looking at if we use 2x 6V6 and what are we looking at if we 2x 6L6, in numbers (V, Ohm, mA, W)? Any comments by the people that are more ¨up to speed¨, more knowledgeable in this subject, are more than welcome. Can someone do some maths for this particular amp. design we are discussing about?
Particularly as it seems that 150mA at the PT for this purpose is OK for 2x 6V6 output valves, and not OK for 2x 6L6 output valves (rather, in a 200mA, as specified by the suggested kit transformer).
What are we really looking at in terms of specific numbers (in Volts and mA) in those two set-ups (2x6V6 and 2x6L6)?
All the best,
Sven
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Ed de Jager
- Posts: 186
- Joined: Fri Jan 14, 2005 4:01 pm
- Location: the Netherlands
Re: D Lite Power Transformer
Please see next post.
Ed
Ed
Last edited by Ed de Jager on Fri Mar 02, 2007 7:24 pm, edited 1 time in total.
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Ed de Jager
- Posts: 186
- Joined: Fri Jan 14, 2005 4:01 pm
- Location: the Netherlands
Re: D Lite Power Transformer
I am sorry;what i should have said was:I am confused about *leaving off the 220K to ground*
What exactly do you mean by that and why should it be done with a 300-0-300 PT and not with a 325-0-325 PT?
Thanks very much in advance!
Greetings,Ed de Jager
What exactly do you mean by that and why should it be done with a 300-0-300 PT and not with a 325-0-325 PT?
Thanks very much in advance!
Greetings,Ed de Jager
Re: D Lite Power Transformer
The last resistor in the dropping string is there to reduce V1 plate voltage to the 200V range. Originally, Scott recommended a 150K resistor to simulate the load that the FET puts on B+5. That worked well on the typical 345-0-345 PT. The D'Lite uses a 325-0-325 to keep plate voltages down on the 6V6 so 220k turned out to be the correct value to adjust B+5. When using a 300-0-300 PT, leaving off the 220k from the end of the dropping string will most likely result in the correct V1 plate voltage.
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Ed de Jager
- Posts: 186
- Joined: Fri Jan 14, 2005 4:01 pm
- Location: the Netherlands
Re: D Lite Power Transformer
I think i see what you mean now;it is the 220K next to the forth 22UF cap right?
I used an early layout where that resistor is not there.
Guess i am lucky this time.
I also saw the 22m resistors and a cap on your new layout that aren`t there in mine,i believe it is the local feedback feedback loop on the second triode.
I am playing with humbuckers equipped guitars and was told that it is worth the trouble putting that part of the circuit in.
What do you think?
Thanks again!
Ed
I used an early layout where that resistor is not there.
Guess i am lucky this time.
I also saw the 22m resistors and a cap on your new layout that aren`t there in mine,i believe it is the local feedback feedback loop on the second triode.
I am playing with humbuckers equipped guitars and was told that it is worth the trouble putting that part of the circuit in.
What do you think?
Thanks again!
Ed