Thanks for the reply. I figured out the resistace value should be arounf 56 ohm (voltage divided by desired current) according to the graphs in the datasheet. I am actually thinking of using a 100ohm pot and go from there.
I did find this site
K & K Audio - Lundahl Transformers, audio DIY kits and more
but would rather go for a single mosfet per channel with the appropriate resistance. I really did not find any hard evidence that would should a cascode design to offer discernible improvement over a single element in builds similar to this one
As soon as I start soldering I will post the results. I believe the use of a current regulator from a differente manufacturer is welcome by those builders who cannot buy IXYS products due to the limitiations curretly in effect (mouse and digikey cannot selle the 10m45 to countries outside the US)
I did find this site
K & K Audio - Lundahl Transformers, audio DIY kits and more
but would rather go for a single mosfet per channel with the appropriate resistance. I really did not find any hard evidence that would should a cascode design to offer discernible improvement over a single element in builds similar to this one
As soon as I start soldering I will post the results. I believe the use of a current regulator from a differente manufacturer is welcome by those builders who cannot buy IXYS products due to the limitiations curretly in effect (mouse and digikey cannot selle the 10m45 to countries outside the US)
I finally got around to powering up my red board using 2 Antek 230V transformers in series for the 600V B+ to 6HJ5s. I used an Antek 40V for the bias supply. I used dummy loads instead of speakers for the first power-up.
I measured 640V for the 6HJ5s, 325V for the main board B+, -55V bias supply, and 145V for the screen. I was able to adjust the bias fairly close as an initial adjustment. Tomorrow I suppose I'll hook up the speakers and run a signal through it.
I used a CL90 after the bridge and before the 500uF filter cap on the upper power supply. How hot do these run normally? I left everything powered up for about 30 minutes and the CL90 is a little hot. I can hold it between my thumb and index finger for about 2 - 3 seconds before I'm tempted to let go.
I measured 640V for the 6HJ5s, 325V for the main board B+, -55V bias supply, and 145V for the screen. I was able to adjust the bias fairly close as an initial adjustment. Tomorrow I suppose I'll hook up the speakers and run a signal through it.
I used a CL90 after the bridge and before the 500uF filter cap on the upper power supply. How hot do these run normally? I left everything powered up for about 30 minutes and the CL90 is a little hot. I can hold it between my thumb and index finger for about 2 - 3 seconds before I'm tempted to let go.
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Ya my CL's run HOT. Alot of people put a piece of shrink wrap on them so they dont dance with the load. I also keep them as far away from anything to give them some air flow. I put mine on the mains though. It would be a breaker popper if you put the CL after a 500va torroid.
On another note, can i just put a piece of shrink wrap on the ul taps and tuck them back into the end bells? I really dont want to cut them off, but they are a tight fit in my grommets.
On another note, can i just put a piece of shrink wrap on the ul taps and tuck them back into the end bells? I really dont want to cut them off, but they are a tight fit in my grommets.
I just finished hooking the amp up to speakers and a source.
WOW! This thing is LOUD and CLEAR! Sounds very good. No noise that I can tell. I measure about 18VAC music program across the speaker terminals with it cranked up pretty darn loud. I don't want to really crank it up until I get the distortion levels set properly.
So far all voltages look good and no smoke. The CL90 doesn't really seem much hotter even under load. The 6HJ5s get pretty hot though!
Now I just need to figure out how to cram all this into a chassis. It's going to be a pretty big amp.
WOW! This thing is LOUD and CLEAR! Sounds very good. No noise that I can tell. I measure about 18VAC music program across the speaker terminals with it cranked up pretty darn loud. I don't want to really crank it up until I get the distortion levels set properly.
So far all voltages look good and no smoke. The CL90 doesn't really seem much hotter even under load. The 6HJ5s get pretty hot though!
Now I just need to figure out how to cram all this into a chassis. It's going to be a pretty big amp.
I powered up my point-to-point build of the DCPP amp, and it has not been smoothe sailing. My power supply is a nice old 340 - 0 -340 Philco transformer with several 6.3v heater windings.
On a dummy load for the speakers, I am getting 18 to 23 volts AC. Yikes. Both speakers. The next clue is that I was floating the various heater windings at some positive DC voltages. When I checked on my voltage divider for this purpose, one of the windings was floating (for my 6CE3 rectifier tubes), but the separate heaters for the 3cb6 drivers and the 6GV5 output tubes are at 0v DC. The heaters are heating but there is 0 ohms DC resistance to ground through the windings. That seems pretty wrong to me.
So, have a fried something in my power transformer, and if so would that be my source of massive noise? Or is my massive noise likely some other problem. I would not think screwy heaters would inject all that much noise. I could try to determine the frequency of the signal on the speakers, and separately could try to supply my heaters from something other than the suspect windings, but thought I would ask for advice in case anyone has encountered my immediate problem before.
Thanks.
On a dummy load for the speakers, I am getting 18 to 23 volts AC. Yikes. Both speakers. The next clue is that I was floating the various heater windings at some positive DC voltages. When I checked on my voltage divider for this purpose, one of the windings was floating (for my 6CE3 rectifier tubes), but the separate heaters for the 3cb6 drivers and the 6GV5 output tubes are at 0v DC. The heaters are heating but there is 0 ohms DC resistance to ground through the windings. That seems pretty wrong to me.
So, have a fried something in my power transformer, and if so would that be my source of massive noise? Or is my massive noise likely some other problem. I would not think screwy heaters would inject all that much noise. I could try to determine the frequency of the signal on the speakers, and separately could try to supply my heaters from something other than the suspect windings, but thought I would ask for advice in case anyone has encountered my immediate problem before.
Thanks.
"I powered up my point-to-point build of the DCPP amp, and it has not been smoothe sailing."
If you are using terminal strips attached to a metal chassis, check to see if you have wired inadvertantly to a lug which is grounded by the mounting bolt.
Otherwise, check the heater winding on the xfmr (disconnected from the circuitry), to see if the problem is internal to it.
If you are using terminal strips attached to a metal chassis, check to see if you have wired inadvertantly to a lug which is grounded by the mounting bolt.
Otherwise, check the heater winding on the xfmr (disconnected from the circuitry), to see if the problem is internal to it.
Thanks Smokin', your suggestion that the lug might be grounded is a good thought, but unfortunately I got that right. My issue is three heater windings that are now in contact with a path to ground internally. Oh well. It is a lovely power transformer, and I think I caused the distress. Only paid $10 for it at a hamfest, and have other good candidates on hand so I can swap it out.
I still suspect I have other issues that are making major noise.
I still suspect I have other issues that are making major noise.
10 pounder transformer
I have been slowly accumulating parts for the red board and have been following George's posts in particular. I believe that the 10 pounder transformers are available again on Ebay as item 320715003628. NOS POWER TRANSFORMER 120 + Watt, Tube Amp #7019. I just ordered 2.
I have been slowly accumulating parts for the red board and have been following George's posts in particular. I believe that the 10 pounder transformers are available again on Ebay as item 320715003628. NOS POWER TRANSFORMER 120 + Watt, Tube Amp #7019. I just ordered 2.
nightanole - Thanks for the reply. I seem go the buy high and sell low route a lot. I was originally going to set mine up as scitizen17 did with Antek power transformers. At the last minute I did a search on Ebay and found the 10lb transformers and changed my mind. This is only my 2nd tube amp build so I liked the fact that Pete made a board (no point to point wiring). I didn't want to vary too much from what people here have been doing. I have the board and the 6hj5s/6gu5s. Now I have to work on getting the OPT's. I'll have the feeling I'm going to be asking advise from here on out. Thanks again
Ya know if you dont want 1.21 jigiwatts of power out of this thing you can just use 1 ten pounder and the 6hj5's loaded at 3.3k and its good for more then double pete's orginal design. So you would have a 50 watt amp that weighs 40 pounds instead of me with a 125 watt amp that weighs 80 pounds ( i think my iron alone weighed 65 pounds).
Ixys IXCP10M45 parts
It seems almost impossible to get the Ixys IXCP10M45 parts in Europe or Asia. So I'll buy a bunch of them, and ship them to those who can't get them. Europe and Asia only, please!
$3.00 each, plus shipping. Shipping runs $6 first class or $15 priority mail. If you need some, please email me off-list, and I'll send a PayPal invoice for payment.
Pete
It seems almost impossible to get the Ixys IXCP10M45 parts in Europe or Asia. So I'll buy a bunch of them, and ship them to those who can't get them. Europe and Asia only, please!
$3.00 each, plus shipping. Shipping runs $6 first class or $15 priority mail. If you need some, please email me off-list, and I'll send a PayPal invoice for payment.
Pete
Hello!
I have just finished the amp. It works beautifully in terms of music quality.
However BIG problem: the output power iss really low. My own laptop maxed out surpasses the amp's power output by far.
The output transofmers have been routed for 8 ohm loads and I am using 6 ohm speakers for test.
I really can't figure out why this is...
Please help!
I have just finished the amp. It works beautifully in terms of music quality.
However BIG problem: the output power iss really low. My own laptop maxed out surpasses the amp's power output by far.
The output transofmers have been routed for 8 ohm loads and I am using 6 ohm speakers for test.
I really can't figure out why this is...
Please help!