I have been looking into building a nice, simple, cheap 6L6 amp for a while. I have heard that the 6L6 is a nice sounding tube, and it seems as though a complete stereo SE amp could be put together for fairly cheap. The missile amp really appeals to me, as it is very simple. Does it look like it would perform well? I know that the tubes shown in the schematics for this amp are not 6L6's, but they are related. Output irons will be Hammond 125ESE's, resistors will be 1W Vishay/Dale, coupling caps will be polypropylene Orange Drops, ecetrolytics will be either Nichicon or Panasonic FC.
I have only a few questions...
If I use a 100k log pot at input (I don't have a preamp and will need volume controls) I then scale the input resistor up to 1M, correct?
How much power would this put out, approximately, with 6L6's running off of +300V supply?
About what mA rating will I need for SE 6L6's?
I will not be making a separate bias supply. How will I go about adjusting the bias of the 6L6's, then? Just put the resistor to ground? Will 470k give me the needed bias at this tube's input?
Thanks in advance
I have only a few questions...
If I use a 100k log pot at input (I don't have a preamp and will need volume controls) I then scale the input resistor up to 1M, correct?
How much power would this put out, approximately, with 6L6's running off of +300V supply?
About what mA rating will I need for SE 6L6's?
I will not be making a separate bias supply. How will I go about adjusting the bias of the 6L6's, then? Just put the resistor to ground? Will 470k give me the needed bias at this tube's input?
Thanks in advance
Revision 3 (6L6GC SE) gets 5W output from 330V 60mA (269AX power tranny). A little NFB to clean up the distortion and it's a sweet little amp.
Omit the 1st stage and tone circuits and use the free 12AX7 section for the other channel, or skip it and use a 6AV6 if you're making monoblocks.
Tim
Omit the 1st stage and tone circuits and use the free 12AX7 section for the other channel, or skip it and use a 6AV6 if you're making monoblocks.
Tim
Attachments
Tim, could you please post some wattage ratings for the resistors in your amp? If I use Ohms Law on some of those I end up needing 100W resistors... that would be both impossible to obtain, and extremely expensive if I could. I am targeting for not much at all. 125ESE's will cost me about $60, then another probably $40 for power transformer, and $20 for inductor, so I am looking at less than $30 for parts. If you will... please provide me with the wattage ratings that work best and the voltage rating on the electrolytic caps. Thanks 
The OPT is a P-T31, meant for 6V6s but seems to work, albeit with a bit of distortion on the bass (the least you can expect). Sounds fine, and seems to take NFB well.
All the 'lytics are rated except for the 6L6's bypass, which has about 20V on it in use; a 35V cap will be fine. It doesn't need to be 470uF either, but I had it around, so I used it.
All resistors are 1/2W 5% carbon film RS resistors ... that's why a few are paralleled. The 6L6's cathode bias can be replaced with a 330 ohm 2 to 5W resistor and the 3x15k in the supply would be 4.7k 1W or so.
Tim
All the 'lytics are rated except for the 6L6's bypass, which has about 20V on it in use; a 35V cap will be fine. It doesn't need to be 470uF either, but I had it around, so I used it.
All resistors are 1/2W 5% carbon film RS resistors ... that's why a few are paralleled.
The 6L6's cathode bias can be replaced with a 330 ohm 2 to 5W resistor and the 3x15k in the supply would be 4.7k 1W or so.Tim
Power is Power?
RMS power is the same as power created if DC were applied.
RMS has been the industry standard for decades. Since we are used to rms, other values give us the feeling of inflated power. "Peak" and "music power" aren't the same.
RMS gives a reference for comparison to other brands. One company mentioned the same thing from another tube, except it turned out the power was 1.8 watts, rms from what I heard.
I relooked the circuit and saw it is running tetrode mode, so my mistake.
If it was running triode mode, I would have said 5 watts rms is out of the question.
RMS power is the same as power created if DC were applied.
RMS has been the industry standard for decades. Since we are used to rms, other values give us the feeling of inflated power. "Peak" and "music power" aren't the same.
RMS gives a reference for comparison to other brands. One company mentioned the same thing from another tube, except it turned out the power was 1.8 watts, rms from what I heard.
I relooked the circuit and saw it is running tetrode mode, so my mistake.
If it was running triode mode, I would have said 5 watts rms is out of the question.
Peak is different than RMS
Peak and Music power is different than RMS.
As mentioned above RMS is the same as if DC were applied to the circuit.
Peak power and Music power are not. Peak power, if I remember correctly, is a figure twice that of RMS power. I think Music power ratings are 4 times that of RMS power.
They are completely different, and one use to seeing RMS as a standard could be given the wrong impression when he sees Peak or Music power figures given.
Just don't want any misunderstandings with customers.
Peak and Music power is different than RMS.
As mentioned above RMS is the same as if DC were applied to the circuit.
Peak power and Music power are not. Peak power, if I remember correctly, is a figure twice that of RMS power. I think Music power ratings are 4 times that of RMS power.
They are completely different, and one use to seeing RMS as a standard could be given the wrong impression when he sees Peak or Music power figures given.
Just don't want any misunderstandings with customers.
Hi Steve;
>>>...Peak power and Music power are not. Peak power, if I remember correctly, is a figure twice that of RMS power. I think Music power ratings are 4 times that of RMS power...<<<
Hmmm, my faves way back in the way back were "JBIE power" (Just Before It Explodes power) and "WLS power" (When Lightning Strikes power)! That latter measure is particularly useful here in the American Heartland due to the impressive thunderstorms and occasional hits on the power lines!! *chuckle*
All the best,
Morse
>>>...Peak power and Music power are not. Peak power, if I remember correctly, is a figure twice that of RMS power. I think Music power ratings are 4 times that of RMS power...<<<
Hmmm, my faves way back in the way back were "JBIE power" (Just Before It Explodes power) and "WLS power" (When Lightning Strikes power)!
That latter measure is particularly useful here in the American Heartland due to the impressive thunderstorms and occasional hits on the power lines!! *chuckle* All the best,
Morse
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