Hello,
I just found out this week that my 211 SE tube amp is 25 years old. It sounds so good I never want to get rid of it. This amp generates a fair amount of heat and is a nice heater in the winter. But heat and age eventually wear components down. What are the most likely components I should look into replacing in this amplifier? I have already replaced some wire wound resistors that had a glazed look to them. There are some electrolyte capacitors in the tube circuit, and film capacitors as well. The big power supply has 6 transformers, 4 chokes, Diode rectifiers, some very big solen film caps and two Agastat delay timer tubes? for the turn on sequence at power on.
I just found out this week that my 211 SE tube amp is 25 years old. It sounds so good I never want to get rid of it. This amp generates a fair amount of heat and is a nice heater in the winter. But heat and age eventually wear components down. What are the most likely components I should look into replacing in this amplifier? I have already replaced some wire wound resistors that had a glazed look to them. There are some electrolyte capacitors in the tube circuit, and film capacitors as well. The big power supply has 6 transformers, 4 chokes, Diode rectifiers, some very big solen film caps and two Agastat delay timer tubes? for the turn on sequence at power on.
I’d be happy to take that from you if you don’t want to bother restoring it…
😆
That said, I’d only think about replacing the electrolytic capacitors. Everything else is likely fine, unless it get very, very hot (50-60C+) in the chassis with normal use…
😆
That said, I’d only think about replacing the electrolytic capacitors. Everything else is likely fine, unless it get very, very hot (50-60C+) in the chassis with normal use…
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Original 211s?You made a funny🤣, no this is truly one of the best sounding amps I have ever heard. Electrolytic's are the second thing on my mid to replace. But runing to the Filaments of the 211 tube are huge 90,000 uF electrolytes, they are located up on top and not subject to the heat the circuit boards see. These I'll bet are very pricy today.
Yes these amps can heat my room up 4-5 degrees in the winter during one of my long listening sessions. No they are not the original 211's I rotate 3 different pairs right now.
I'm more in the "ain't broken, don't fix" camp so I wouldn't touch it if it still works. I wouldn't bother replacing resistors unless they're no longer meet spec. Electrolytic capacitors will dry out eventually.
Why not measure the performance of the amp and then decide whether to mess with it. I'd look at the frequency response and distortion vs frequency and output power.
Tom
Why not measure the performance of the amp and then decide whether to mess with it. I'd look at the frequency response and distortion vs frequency and output power.
Tom
Good plan, I'll have to pull clio out and run the tests on it to see. I would expect it to measure pretty good. several years ago it measured very good. It has developed a slight soft ticking lately. Very quiet and in the L channel mainly I believe. That could be a poor solder joint or soldering over a bunch of old flux which is messing with the connection. Most components are soldered to a "turret" like post. not as easy as soldering to a PCB.
Happy anniversary. 😀
An RF sniffer, even a simple one as described here may help you trace the source if the ticking comes from arcing.
Attached internal shot of the amplifier. Power supply is 2/3's of the chassis. The input/output board is between the 211 sockets. Those electrolytes on the side of the amp just above the 211's connect in the filament/bias circuit of the 211 tube. These might be candidates to replace as it gets toasty there. I have replaced the grid to plate coupling resistors barely seen above the blue teflon solen caps, which are also upgraded from regular film caps, and to the outer edge of the lower blue Teflon caps. Last weekend I replaced a 1K and 2-25 ohm resistors in the same filament/bias circuit for the 211 that those electrolytes also serve. The 1K's are located on the lower outer edges of this board and the 25 ohms are just above them.
What value of capacitance is this capacitor? the schematic says it should be 3.5uF, 100v. You can also see better the 1K and 2-25 ohm resistors before I replaced in this picture.
What value of capacitance is this capacitor? the schematic says it should be 3.5uF, 100v. You can also see better the 1K and 2-25 ohm resistors before I replaced in this picture.
That is the risk of messing with something that's working.
It's also possible that you're just now noticing this. Try turning your wifi and cell phones off (airplane mode).
Looks like 1.25 uF, 100 V. K is the tolerance if I recall correctly. 1.25 uF is an odd value. Capacitors tend to follow E6: 1.0, 1.5, 2.2, ... 6.8. Sometimes E12: 1.0, 1.2, 1.5, 1.8, 2.2, ... 8.2.
The black power resistors? They look fine in the picture.
Tom
It was ticking much worse before replacing those resistors. My guess now is solder joint or excess flux messing with turret and clean signal transfer.
Visually the board beneath was discolored and the resistor looked pretty worn, so I just went ahead and replaced with same value.
Does the ticking subside after a while? It could be a thermal thing. If the ticking remains even after hours of warmup, I'd go looking for crappy connections in sockets and the like. I suppose a dying tube or capacitor could do that too. Or maybe something is arcing over because of dust/grime collection.
Many seem to forget that power resistors will reach 250-300 ºC when operated at their rated power. Even with 3-4x de-rating, which is what I normally use, they'll reach 80-100 ºC. Over time anything near the resistor will develop a bit of 'patina'. 🙂
Tom
The, now very soft ticking, usually doesn't start until the amp is on for 3 hours sometimes even 4 but once starts will remain until I turn it off. Replacing resistors definitely helped, but you can see in the pic a lot of flux on those turrets, so some of that could interfere with a clean signal transfer I suppose. I'll focus on the coupling ones between grid and plates and clean turret with acetone and pipe cleaner then resolder with my Weller digital iron with the biggest tip on, I use cardas solder. Then maybe some of those electrolytes will be next to replace. Might even replace 6sn7 and bx7 tube sockets but that looks to be a major PIA, I cleaned them pretty good. Tubes have been swapped and have no effect on the ticking. It is pretty soft now tho, a good thing I guess.
One more interesting development. I finally managed to get one of those Topaz very low interwinding capacitance isolation transformers. I have plugged my amps and dac into this transformer. Its been two weeks now and I no longer can detect any ticking at all, Hmmm. When the amp was plugged straight into the wall or another Tripp-lite isolation transformer I had very soft ticking, now with the topaz it appears gone. So maybe it was something on the AC line?