Also, I just checked the anode current of the ECC83. It looks like one anode draws 1.2mA. So 1.2 x 2 = 2.4mA which would give me about the same voltage off the PSU that I've been seeing.
I'm betting the first stage is OK, but the second stage needs some examination of the grounding.
Any ideas about the filament no-glo in the ECC88?
As always, thanks for the great advice. I already feel better. Or less murderous.
Kofi
I'm betting the first stage is OK, but the second stage needs some examination of the grounding.
Any ideas about the filament no-glo in the ECC88?
As always, thanks for the great advice. I already feel better. Or less murderous.
Kofi
Kuei Yang Wang said:
And, is there a reason for this nanovolt filtering? (Heh, tunneling noise (if that happens on a dielectric?) is probably more significant.) Even instrumentation amps don't do such a useless trick. Of course, those are regulated, for stability as well, but the circuits are still designed much better than to need much filtering anyway. (Or at least I would hope so.)
I long ago decided which is better. Heck, you could even go with a single 220uF banger on the rectifier, no other filtering, and have sufficient performance. A bit brute-force, but who cares at 5mA.
Tim
Hey, this is all about ME, remember? Me, me, me, me, me, me, me, me, me, me, me, me......
Whoa. I sound like Mrs. Annan.
Anyhow, two more questions:
1. Any advice on the no-glo on the filaments for the ECC88? I measured the correct voltage on the pins, but no glow!
2. Should I have grounded the screen (pin 9) on the ECC88? I connected the screen (pin 9) with the cathode (pin 8), since the cathode is directly grounded, and I tied them to ground.
Thanks again for all the advice. There's no way my power bill would be as outrageously high as it is without all your help.
Kofi
Whoa. I sound like Mrs. Annan.
Anyhow, two more questions:
1. Any advice on the no-glo on the filaments for the ECC88? I measured the correct voltage on the pins, but no glow!
2. Should I have grounded the screen (pin 9) on the ECC88? I connected the screen (pin 9) with the cathode (pin 8), since the cathode is directly grounded, and I tied them to ground.
Thanks again for all the advice. There's no way my power bill would be as outrageously high as it is without all your help.
Kofi
Tim, if you've got a copy of Morgan Jones 3rd edition, take a look at the table on p 326. Or go back to the source and read the article by "Cathode Ray" in Wireless World, October 1949. There is a significant advantage to sectioning RC; it's actually one of those things which is not from the fevered imagination of the audio fashion crowd.
Konnichiwa,
Okay, performance....
Supply 1 - 220uF after rectifier, no added filtering, this gives 1.5V Peak-Peak Ripple.
Supply 2 - 47uF reservoir capacitor, 10H Choke, 220uF Filter Capacitor, this gives 5mV peak-Peak Ripple.
Supply 3 - as designed by me with 47uF followed by 4pcs of 1K2/47uF Filter cells, this gives 0.0025mV Peak-Peak ripple.
The circuit supplied has fairly low PSRR @ 100Hz, in the region of 36db/60 Times.
Supply 1 will produce around 25mV Peak-Peak (9mV RMS) noise on the output of the supplied Phonostage, or a S/N ratio of -35db (below 500mV output) for 100Hz hum. Not just brute force, but apprarently with no brains at all. Completely unacceptable.
Supply 2 will produce around 84uV Peak-Peak (28uV RMS) noise on the output of the supplied Phonostage, or a S/N ratio of -85db (below 500mV output) for 100Hz hum. Probably acceptable (but still actually quite crummy for all the extra expense), but the choke and big value high voltage capacitor cost a lot more than my filter resistors and capacitors.
Supply 3 will produce around 42nV Peak-Peak (14nV RMS) noise from the 100Hz hum, in other words well far past good and evil (-151db) so if you have hum, it is not from the supply.
Some interesting observations accrue if you look at the transient behaviour of the supplies. Another interesting thing becomes notable if we look at the behaviour higher up in frequency, where the choke becomes resonant and capacitive and the big electrolytic capacitor quite inductive, but those are other issues.
If you want a cheap and effective low noise supply for a preamp you can do much worse than buying 6pcs of Nichicon VX Series 47uF/450V electrolytics at 50 cent each and 4 pcs 1K/2W Metal Film resistors at 10 cent each. Certainly most regulators are MUCH worse and cost more....
Sayonara
Sch3mat1c said:
Okay, performance....
Supply 1 - 220uF after rectifier, no added filtering, this gives 1.5V Peak-Peak Ripple.
Supply 2 - 47uF reservoir capacitor, 10H Choke, 220uF Filter Capacitor, this gives 5mV peak-Peak Ripple.
Supply 3 - as designed by me with 47uF followed by 4pcs of 1K2/47uF Filter cells, this gives 0.0025mV Peak-Peak ripple.
The circuit supplied has fairly low PSRR @ 100Hz, in the region of 36db/60 Times.
Supply 1 will produce around 25mV Peak-Peak (9mV RMS) noise on the output of the supplied Phonostage, or a S/N ratio of -35db (below 500mV output) for 100Hz hum. Not just brute force, but apprarently with no brains at all. Completely unacceptable.
Supply 2 will produce around 84uV Peak-Peak (28uV RMS) noise on the output of the supplied Phonostage, or a S/N ratio of -85db (below 500mV output) for 100Hz hum. Probably acceptable (but still actually quite crummy for all the extra expense), but the choke and big value high voltage capacitor cost a lot more than my filter resistors and capacitors.
Supply 3 will produce around 42nV Peak-Peak (14nV RMS) noise from the 100Hz hum, in other words well far past good and evil (-151db) so if you have hum, it is not from the supply.
Some interesting observations accrue if you look at the transient behaviour of the supplies. Another interesting thing becomes notable if we look at the behaviour higher up in frequency, where the choke becomes resonant and capacitive and the big electrolytic capacitor quite inductive, but those are other issues.
If you want a cheap and effective low noise supply for a preamp you can do much worse than buying 6pcs of Nichicon VX Series 47uF/450V electrolytics at 50 cent each and 4 pcs 1K/2W Metal Film resistors at 10 cent each. Certainly most regulators are MUCH worse and cost more....
Sayonara
OK-- checked all the grounds and they're fine. Tested the E88CC and its fine (I was kinda hoping that was it). I'm going to re-solder all the joints tomorrow morning, but it just kills me that it won't work.
What is interesting is that the first stage seems fine. The filaments glow and I'm getting about what I'd expect in voltage on the pins (about 214V on the ECC83).
Curiously, the second stage is TOTALLY DEAD (E88CC). I get the same 385V no matter where I look (at the PSU, at each resistor, at the anodes) and the filaments are showing a steady 6.3VDC (regulated), but the damn thing WON'T GLOW!!! Its like a brick!
I tested the tube an it glows in the tester and measures "good", but nothing else I do seems to work.
Could it be the tube socket somehow?
Anyway, I'm taking the whole damn thing apart tomorrow. I wanted to do this to learn, and I'm OK with that. Its just the homicidal rage that accompanies the learning that I worry about.
Any advice would be greatly appreciated.
Here's the circuit again for reference.
Thanks,
Kofi
What is interesting is that the first stage seems fine. The filaments glow and I'm getting about what I'd expect in voltage on the pins (about 214V on the ECC83).
Curiously, the second stage is TOTALLY DEAD (E88CC). I get the same 385V no matter where I look (at the PSU, at each resistor, at the anodes) and the filaments are showing a steady 6.3VDC (regulated), but the damn thing WON'T GLOW!!! Its like a brick!
I tested the tube an it glows in the tester and measures "good", but nothing else I do seems to work.
Could it be the tube socket somehow?
Anyway, I'm taking the whole damn thing apart tomorrow. I wanted to do this to learn, and I'm OK with that. Its just the homicidal rage that accompanies the learning that I worry about.
Any advice would be greatly appreciated.
Here's the circuit again for reference.
Thanks,
Kofi
Konnichiwa,
Hint, disconnect for the time being the HT (so you are not mortally afraid of touching the thing powered up) and find why the ECC88 heater refuses to light up. Because no glow no go for the electrons and ths no current drawn and thus the +B is what it should be, given the circumstances.
Sayonara
Kofi Annan said:
Hint, disconnect for the time being the HT (so you are not mortally afraid of touching the thing powered up) and find why the ECC88 heater refuses to light up. Because no glow no go for the electrons and ths no current drawn and thus the +B is what it should be, given the circumstances.
Sayonara
Interesting... so you're saying that withou any glow on the filaments, regardless of the circuit, it will not draw current, right?
Another thought came to mind. I bought a JJ / Tesla E88CC for the second stage. I know its a long shot, but is it possible that the pinout is different for this tube?
Probably not, but its worth asking.
Kofi
Konnichiwa,
I would hope that it would not. The ECC83 and the ECC88 have different heater connections.
I repeat, disconnect the +B entierly (and discharge the capacitors) and then find the fault.
Disconnect the HT so you stay healty, bad enough to get a new pope anytine soon, a new SecGen of the UN at the same time would really screw the plans of the illuminati up....
Sayonara
Kofi Annan said:
I would hope that it would not. The ECC83 and the ECC88 have different heater connections.
I repeat, disconnect the +B entierly (and discharge the capacitors) and then find the fault.
Disconnect the HT so you stay healty, bad enough to get a new pope anytine soon, a new SecGen of the UN at the same time would really screw the plans of the illuminati up....
Sayonara
Konnichiwa,
The ECC88 has a 6.3V Heater connection (both systems in parallel) between pin 4 & 5 and pin 9 as screen..
The ECC83 has one 6.3V Heater per system between pin 9 and pin 4 or 5. That means between pin 4/5 you have a 12.6V Heater voltage, or a 6.3V Heater voltage if you short pin 4/5 together and apply the heater voltage between pin 9 & pin 4/5.
If your ECC83 lights up with the heater voltage connected to pin 4 & 5 this suggests you have a 12V Heater voltage and if connected the ECC88 to that you have one dead ECC88.
If not, have yoummixed up ECC88 & ECC83?
Sayonara
Kofi Annan said:
The ECC88 has a 6.3V Heater connection (both systems in parallel) between pin 4 & 5 and pin 9 as screen..
The ECC83 has one 6.3V Heater per system between pin 9 and pin 4 or 5. That means between pin 4/5 you have a 12.6V Heater voltage, or a 6.3V Heater voltage if you short pin 4/5 together and apply the heater voltage between pin 9 & pin 4/5.
If your ECC83 lights up with the heater voltage connected to pin 4 & 5 this suggests you have a 12V Heater voltage and if connected the ECC88 to that you have one dead ECC88.
If not, have yoummixed up ECC88 & ECC83?
Sayonara
Kofi Annan said:
Kofi,
On both tubes the heaters are on pins 4&5 according to your datasheets. And both are parallel connected heaters.
However the E83CC can be connected to 12.6V for the heaters. Someone with more experience than I will have to chime in with the difference in the way the heaters are connected for 12.6V vs. 6.3. (Don't ground pin 9 when using 6.3v?)
OK, really confused now.
For the ECC83, I have regulated 6.3VDC going to pins 4+5 with both pins soldered together and pin 9 grounded.
Wrong?
I had the same for the E88CC, but if I need to wire this in parallel, is it as simple as splitting one 6.3VDC wire into two and wiring one to pin 4, one to pin 5 and NOT soldering them together?
Wow, I'm a dumbass. Thanks so much for the advice.
Kofi
For the ECC83, I have regulated 6.3VDC going to pins 4+5 with both pins soldered together and pin 9 grounded.
Wrong?
I had the same for the E88CC, but if I need to wire this in parallel, is it as simple as splitting one 6.3VDC wire into two and wiring one to pin 4, one to pin 5 and NOT soldering them together?
Wow, I'm a dumbass. Thanks so much for the advice.
Kofi
Right for the ECC83, wrong for the E88CC.
The heater of the ECC83 is center-tapped, with pins 4 and 5 each connected to a different end and pin 9 connected to the center. You can either connect 12.6V between 4 and 5 (that is, connect +12.6VDC to one end and ground the other) and leave 9 disconnected, or you can connect pin 4 to pin 5 which parallells the two halves, and then connect 6.3V between the joined 4&5 and pin 9. Either way, each half of the filament (between pins 4 and 9, and between pins 5 and 9) has 6.3V across it.
If it helps, picture bending a piece of wire into a v-shape, bringing the ends together. What was once the middle (pin 9) becomes the end.
The E88CC's filament is not center-tapped, so pin 9 has nothing to do with it. It only has two pins (4 and 5) connected to the ends. If you look at the diagram, you can see that the two sections' filaments are wired in parallel inside of the tube. It needs 6.3V across the filament, but if you've connected together pins 4 and 5 on this tube, then you've short-circuited the ends together and ensured that there is always zero volts across the filament. Connecting the same +6.3VDC wire to both ends would have the same result: both ends would be at +6.3VDC, so there would be zero volts across the filament. You need to connect +6.3VDC to one end (either pin 4 or pin 5) and ground the other end.
Hopefully this clarifies things,
Aaron
YYYEEEAAAAHHHH!!!!
Thats what I'm talkin' about!!!
This has to be the problem. Too loaded now to mess with it, but you can bet I'll be on it first thing tomorrow morning. Well, second thing actually... I got this issue with the Saudi prince arrested for drug trafficking to deal with but RIGHT AFTER THAT....
Thanks so much for all the help. I'll report tomorrow morning.\
Kofi
OK. sop its not exactly tomorrow morning, but there were a few mishaps along the way.
The phone guy came over and installed a few jacks and decided he'd disconnect my ADSL service as well for no extra charge. Got that reinstalled on Sunday, but then I had yardwork and blahblahblah....
Anyway, the filament problems were the entire issue and the thing works great.
I am really suprised at what an improvement it is over my cheapie solid state phono preamp! Really detailed and sweet. Thanks to all who helped me through this. I'll take some pictures this weekend and post them.
Its got a really bad hum, unfortunately, which is likely due to an onboard PSU. If you can feel the amp vibrating when its turned on, that's going to lend to a bad hum.
I'm going to insulate the transformer from the chassis this wekeend and see if it makes a difference.
Thanks to all who helped me out!
Kofi
The phone guy came over and installed a few jacks and decided he'd disconnect my ADSL service as well for no extra charge. Got that reinstalled on Sunday, but then I had yardwork and blahblahblah....
Anyway, the filament problems were the entire issue and the thing works great.
I am really suprised at what an improvement it is over my cheapie solid state phono preamp! Really detailed and sweet. Thanks to all who helped me through this. I'll take some pictures this weekend and post them.
Its got a really bad hum, unfortunately, which is likely due to an onboard PSU. If you can feel the amp vibrating when its turned on, that's going to lend to a bad hum.
I'm going to insulate the transformer from the chassis this wekeend and see if it makes a difference.
Thanks to all who helped me out!
Kofi
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