The indirect heated ones have longer warm up times than direct heated.
5AR4 is a good one if you want a longer delay. If I recall right, it's 20-30 seconds.
Damper diodes have a long delay as well, but they only come in single diode per envelope as far as I know.
The only tube rectified amp I have uses 5U4GB which only takes like 5 seconds. Unfortunately the rest of the tubes in the amp aren't conducting yet at that time, so B+ will rise about 100V over the steady-state value, for a short moment after power on.
5AR4 is a good one if you want a longer delay. If I recall right, it's 20-30 seconds.
Damper diodes have a long delay as well, but they only come in single diode per envelope as far as I know.
The only tube rectified amp I have uses 5U4GB which only takes like 5 seconds. Unfortunately the rest of the tubes in the amp aren't conducting yet at that time, so B+ will rise about 100V over the steady-state value, for a short moment after power on.
Thanks Jeb-D.
The reason I ask is that I need to sub in a 6087 or 6106 for my 5Y3GT for the same reason you gave and was curious about those warmup times. I should have asked that in the first post. I know the warmup time for a 5V4G is nearly long enough and only puts my startup voltage about 50-60 volts over idle B+, which is fine except for the 25 extra volts on the B+ at idle that will cause havoc. The 5Y3GT on the other hand peaks the startup voltage at over 200V above idle voltage. It a choke I/P so I realize that there's no enough current draw initially , but I'd just as soon change the rectifier as to add an extra bleeder that's going to make tons of heat or switch the power tube filaments on first (which is still an option at this point).
Like I said, I used to have a whole table of like 30 different rectifiers (direct and indirect) and all their specs. It would be useful for other builds to know what all the options are.
I'll dig some more and see if I can find it.
The reason I ask is that I need to sub in a 6087 or 6106 for my 5Y3GT for the same reason you gave and was curious about those warmup times. I should have asked that in the first post. I know the warmup time for a 5V4G is nearly long enough and only puts my startup voltage about 50-60 volts over idle B+, which is fine except for the 25 extra volts on the B+ at idle that will cause havoc. The 5Y3GT on the other hand peaks the startup voltage at over 200V above idle voltage. It a choke I/P so I realize that there's no enough current draw initially , but I'd just as soon change the rectifier as to add an extra bleeder that's going to make tons of heat or switch the power tube filaments on first (which is still an option at this point).
Like I said, I used to have a whole table of like 30 different rectifiers (direct and indirect) and all their specs. It would be useful for other builds to know what all the options are.
I'll dig some more and see if I can find it.
burnedfingers said:
I was thinking of taking this approach in an amplifier project.
AFAICT,it should work okay,assuming you can find a damper diode that is rated for the current you need,and the voltage drop is acceptable,etc.
I was thinking of putting the damper in series with the rectified B+ line,probably directly after the SS didoes.
I have heard some chatter about people using this method for a slow-start,but have never seen a schematic or anything.
Eli Duttman said:I spoke to Jim McShane today about the 6106. Jim stated that startup time is in the 45-60 sec. range.It makes sense, given the machined ceramic block that supports the heater. A large mass has to be heated up.
Thanks Eli.
You wouldn't know how the 6087 compares to 5V4G warmup, would you. I know the 5V4 was very close to solving my B+ startup surge problems. I hate to put in any larger bleeder than necessary just to keep the heat under the chassis down.
Everybody talks about the Bendix 6106, I wonder how the other makes stack up.
bloozestringer said:
B+ rise time for the 5Y3WGTB/6087 should be quite similar to that of the 5V4/GZ32.
AFAIK, branding of 6106s is irrelevant. I believe that all 6106s were manufactured at Eatontown, NJ. The 6106 is rather special. Its sonic reputation is sterling, along with the very obvious toughness. Remember, the 6106 was OEM in the US Army's Nike SAM guidance system.
Eli Duttman said:
B+ rise time for the 5Y3WGTB/6087 should be quite similar to that of the 5V4/GZ32.
AFAIK, branding of 6106s is irrelevant. I believe that all 6106s were manufactured at Eatontown, NJ. The 6106 is rather special. Its sonic reputation is sterling, along with the very obvious toughness. Remember, the 6106 was OEM in the US Army's Nike SAM guidance system.
Thanks again, Eli. I'll get one or the other ordered for my amp before I do any more with it. Once I get the startup voltage under control, then I can transfer it to a proper chassis. Here's the schematic with voltages I've measured in red, FWIW.
Attachments
I'm re-opening this thread to see if anyone has this information. I built an amp that uses 2 rectifier tubes the 5Y3GT for the HT and a 6CA4 for the Bias. I thought it would be cool to not have any solid state in the amps.
I think the HT is coming up before the Bias causing pre-mature power tube failure. If I could see a chart I can change out one or the other to insure the Bias is up before the HT comes it. If the Bias (6CA4 was an octal tube I’d just replace it with a solid state rectifier but it’s not. I gave these amps to my brother across the country or I just put in solid state diodes for the Bias supply. There monoblocks I’d hate to make him ship them back to me.
I know some datasheets have the warm-up time but most don’t. from a headphone amp I have using a 6CA4 the warm-up time is around 13 seconds. Both rectifiers tubes are new not NOS.
If it takes you 30 seconds to unscrew and remove the bottom plate off of an amplifier . . . Then you need to install a bleeder resistor on the B+ that drains it down to 42 Volts within 30 seconds.
Safety first.
Now, some of you are going to want to know where I got the 42 Volt figure from, right?
Safety first.
Now, some of you are going to want to know where I got the 42 Volt figure from, right?
I use a $1 time delay circuit to short a resistor after the initial surge into the caps. Not as pretty as a damper, but works and is more efficient. When I did use tube rectifiers I used 6DE4 dampers. About 30 second warm up.
NE555 DC 12V Delay Relay shield Timer Switch Adjustable Module 0 To 10 Second | eBay
NE555 DC 12V Delay Relay shield Timer Switch Adjustable Module 0 To 10 Second | eBay
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42V is a safe margin from the 50V or so that you start to feel a shock from.
For me to use such a large bleeder would be a giant waste (440V 3300uF) so I use a 100k resistor and know that it takes about 10 minutes to bleed down. I also install either a neon (or LED with a 1M dropper) or a voltage gauge as a visual reminder that there is still energy in the caps.
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I use a 555 timer controlled relay to delay the filament voltage to rectifier tube(s) to control the onset of B+. K&K Audio sells a compact kit and Kevin will supply it with Schottky diodes and a low dropout regulator so it can be powered from the same 5V winding as the rectifier. BTW, I have mono- blocks with 6CM3 damper diodes in a hybrid bridge. Without extra delay the B+ comes up before the KT-120 output tubes are ready to conduct. With 4 output tubes (PPP configured as an LPT) sitting on a single CCS the first KT-120 to warm up would be hit with all 300mA of bias. An extra 30s delay solves that issue.
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