Hey George. You recommend the AN-1T200 for 6CW5-based duty, but it's only rated for 220mA. Has yours worked well overloaded that much? AN-2T230 seems a little on the high B+ side, but it has the right amount of VA. Too bad they don't have a 2T200.
I don't see any current offering from Edcor that would work. Closest match is the XPWR099, which is 200-0-200 @ 1A. No heater winding, though, and expensive to have so much extra capacity. Would work great for a 4-channel amp, though!
I don't see any current offering from Edcor that would work. Closest match is the XPWR099, which is 200-0-200 @ 1A. No heater winding, though, and expensive to have so much extra capacity. Would work great for a 4-channel amp, though!
Anteks own spec page shows the output voltage for the AN-0105 dropping to 4.5 volts with a 1.75A load. This doesn't look too good for lighting up a 5AR4.
I have a 2T300, a 3T325 and a 2T350 on order. Smoke testing will begin when they arrive. I already have a 4T360 (really makes em glow) and a 4TK400 (don't even think about it).
I have the 4T360 running two Simple P-P boards at the same time. The 5AR4's on each board are hooked up, but the B+ is about 425 volts. This is so far over spec that I don't recommend it, but I am getting almost 60 WPC! Amp construction is underway. No wimpy EL84's need apply here. How do you light the 5AR4? by winding two additional secondaries on the Antek, one for each tube. It may be possible to run the 5AR4 off of one of the 6.3 volt windings on the 3 transformers mentioned above with a dropping resistor, but I won't know until I try it.
I built an amplifier using the 1T200 last year. It didn't get hot. I had it running daily for about 2 weeks, until I took it apart to finish the cabinet and photograph the reassembly. Well, "stuff" happened and it still hasn't been reassembled yet. I ordered a 2T230, which does not fit my cabinet because it is bigger than Antek says it is. I connected it up in place of the 1T200 with no other changes. The red glow of death came to visit quickly, so I shut it off. That was last year. Further testing will occur, maybe next weekend.
Anteks spec sheet doesn't mention 220mA. The transformer is rated for 100VA, and "In most of the cases, this transformer can be output 20% more
power from its rating at 60Hz power source without any problem." There are about 23VA used to light the heaters. The idle current is about 100 mA per channel running from a 270 volt supply this is another 54 watts. So at idle we are drawing 77 VA from a 100 VA transformer (neglecting the losses due to conduction angle). Now running the amp at full rated power can draw 400 mA or so, which will consume 123 VA (B+ drops to about 250V) which is close to the "20%" over rating, and slamming the amp into hard clipping can hit 150 VA. So it ight be possible to warm up the transformer if you run the amp hard with a sine wave at the power limit, with real music the average is likely well under 100VA unless you really like distortion.
The value of R1 is dependent on the power transformer being used, and how it is connected up. I will make a table of values as I do more testing, but for most "normal" builds there are two choices. 39 ohms for a 6CW5 amp, and 150 ohms for an EL84 amp. Both of these are included in the parts kit.
The differences between the two builds are all related to the OPT's and the power supply. As far as the board goes, the 6CW5 gets 39 ohms for R1 and 1N5408's or UF5408's in place of the octal socket. The EL84 build gets an octal socket and a 150 ohm resistor. All other components are the same for both builds.
Sounds good. I got the 220mA off the front page for the transformer. Like you said, that is based on a fully-loaded 6.3V winding. The spec sheet tells a different story.
Same cathode resistors too? Cool.
So far 270 ohms has worked in everything that I have built, even the mega powered versions. Most EL84 amps will drop 10 or 11 volts across these resistors. A 2 watt resistor should be sufficient. The 6CW5 amps however wind up with about 20 volts across the cathode resistors in normal operation. I managed to blow up a 2 watt resistor when driving the amp with my guitar preamp, so all amps get 5 watt resistors.
So far that cathode resistor is the only thing that I have blown up with the 5 boards that I have been playing with.
The Ei 7189A's that I have are obviously relabled Russian tubes, probably 6P14P's. The pins on many Russian 9 pin tubes are very sharp. The ones in the picture have rounded pins, but we don't know anything else about them. They cost $35 plus $12 shipping for 4 tubes. I can get JJ EL84's cheaper than that and I know that they put up with my abuse.
I will call my usual tube supplier and find out what he has in 6CW5 and the price. Training all day tomorrow, and all day meetings Wed and Thurs
Might not happen until Friday.
I just got off of the phone with Stan (ESRC). 6CW5 GE is $5 each, Amperex is $6. He has other brands, but I have not tried any of them yet. Next time I have the oportunity to physically see the tubes, I will get some for testing. There is a hamfest in late March, but neither Stan or I know for sure if we are going yet.
I know that I have found the short plate Canadian RCA's and the Sylvania ECG's with "mystery guts". Neither worked well at power levels that were within the 6CW5 specs, so I would avoid those brands unless you can see what you are getting.
7189 and 7189A are different tubes. The 7189A is rated for 400 volts on the plate! I got 4 of the JJ EL84's 6 months ago. I have been running them at the upper limit of 7189A, and maybe a bit beyond (420 volts B+). They dont glow, and just work. 4 in PPP make almost 60 watts! I bought 12 more at the Hamfest, but haven't tried any of them yet. The price went up in the past 6 months
I had that amplifier running for about 3 days before I took it apart to use the board in a more conventional way. I never made any serious measurements other than output power. Then I listened to it for a couple of days, decided that I would build one, and moved on.
I used a variable power supply and kept turning it up while checking for tube glow. I stopped turing things up when I saw 60 watts on the meter. I was at 420 volts. I saw the JJ's and some 1963 vintage Sylvania's work at this level, but the Russian tubes and the Ei's that I tried would glow if I went past 330 volts! It is safe to assume that I was a bit over spec, and I will probably shoot for 40 to 50 WPC when I build the final amplifier.
Sounds perfekt, thank you
Hmm, I suppose that more tubes means output trafos with lower impedance, and generally better ?
I never said anything, but people have been sending me money, and I have been sending out boards. As with the other boards the price is $35, with $8 shipping in the US, and $15 internationaly.
I an still holding off on the parts kit until someone who I sent a kit to finishes their build without any problems.
Understand that the PC board assembly instructions are now on the web site. They were written in bits and pieces in hospitals, hotel rooms, and my mother in laws house, and assembled when I got home. I have been advised of a few minor issues that I will fix next weekend. The parts list is the wrong one. I will post the correct parts list next weekend. The connection diagrams are not finished yet, and with my current work schedule, it may be 2 weeks away.
I will post updates as they come.
The correct parts list should be on the web site now. It matches the last two boards that I built, and should match the parts kits that will be available soon. The parts kist that went to early adopters and beta builders may have slightly different values for two capacitors.
Twice as many tubes, half the impedance. In my case I am using the same OPT, just connecting my 8 ohm load to the 16 ohm tap. In theory it should be easier to design a 3300 to 8 ohm OPT than a 6600 to 8 ohm OPT.
Twice as many tubes, half the impedance. In my case I am using the same OPT, just connecting my 8 ohm load to the 16 ohm tap. In theory it should be easier to design a 3300 to 8 ohm OPT than a 6600 to 8 ohm OPT.
I've noticed something a little strange about the construction manual, in that there is no mention of what the input tubes are. I believe from reading on other threads that they are 12AT7, but it might be a good idea to put that in the manual. Actually I can't find any mention of the input tube anywhere on tubelab.com
I'll eat my words if I'm wrong...
I'll eat my words if I'm wrong...