Bottlehead Forum
Bottlehead Kits => Legacy Kit Products => Paramount => Topic started by: andy2667 on October 21, 2009, 06:20:41 AM
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Hi,
I Just upgraded the parafeed copling cap and replaced my old Sovtek 2A3 by Shuguang 2A3c. I can only have listening session during week ends or sunday for 2~5 hours a day. Want to burn in the new cap and tube quicker instead of waiting for months to explore the full potential of the new cap and tube. Never run the paramount more that 6 hours continuously and the power transformer seems to be a little bit hot. Just curious to ask if the Paramount can be operated on 24hrs round the clock basis without damaging the transformer and the cathod resistors (this part is very hot!).
I configured the paramount in 2A3 direct coupling configuration.
Thanks
Andy
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I can't answer the 24/7 question about your Paramounts... but...
I have a "Patented" burn in method:
How to break in the easy way
Buy yourself four Radio Shack 10W 10 Ohm resistors. These are among the few parts they still sell. You should always keep these on hand because you can use 10 ohms as a dummy 8 ohm load. The value is close enough.
Determine the volume level for break in with a CD of your favorite music. You want a loud but not distorted level for break in. Determine the right volume level and remember this setting on your preamp or amp. This is the break in level.
Wire each pair of resistors in parallel (see picture below), then put one capacitor in series with what is now a 5 ohm load (a good load for the amplifier). The first lead of the capacitor goes to one amplifier speaker terminal and the other lead goes to one of the the joined leads of the 10 ohm resistors. The other joined leads of the 10 ohm resistors goes to the other amplifier speaker terminal. You will end up with a pair of resistors and a capacitor on each of the amplifier speaker terminals. (couldn't insert a picture in between the text so it is below) I use a dual banana plugs because it is easier that way for me.
Now, with only the resistors and capacitors on the amp output, no speakers, put your CD on repeat, set the volume level at the predetermined point and burn in the caps for 4 days, ~100 hours for polypropylene and polyethylene caps. Burn in for 1-3 weeks if they are Teflon.
Using the pair of 10 ohm resistors in parallel feeds twice the current through the capacitor than a 10 ohm resistor and increases/speeds burn in.
That is it. After 7 days, or 21 days for Teflon, you should have 90% burned in capacitors. Any changes that happen after that will take many, many weeks anyway. Break in is not a straight line but a curve.
(I got tired of soldering the capacitor leads so I have replaced the wires with alligator clip leads.)
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Hi Grainger... what is the value of the capacitor.
Thanks
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Frank, sorry, I really wasn't clear in the beginning of my post.
This procedure is for burning in a left and right channel capacitor before inserting into the circuit. I use my workshop system, with a solid state GainClone, for burn-in. I wouldn't want to run a tube amp 24/7 because it is a waste of tube life.
If you want to run in the new Parafeed cap in your Paramounts now after assembly, put a 10 ohm resistor alone across your speaker terminals, leave the speakers off. That will draw the signal current through the Parafeed cap.
There are a couple of nice things about my procedure. First, it mimics PJ's suggestion about drawing full load current without being as scientific as PJ is. Then using the speaker output to burn in the capacitor puts higher current through it than in the Parafeed position (well, maybe not depending on the turns ratio of the transformer). The 5 ohm resistive load lowers the first order high pass nature of the set up (passes a wider frequency band through the cap) and the 5 ohms increases the current from a SS amp.
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Gotcha.... I was under the impression you were burning in the amps as a whole unit.... muchas gracias.
Thanks again.
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Too bad that I have already soldered the replacement cap in the amp. Maybe, I would better run in the whole amp together as I need to run in the new shuguang 2A3c as well.
Thank you for your advices.
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Too bad that I have already soldered the replacement cap in the amp. Maybe, I would better run in the whole amp together as I need to run in the new shuguang 2A3c as well.
Thank you for your advices.
Yeah, at this point it is either yank them out and burn in or burn in place. If the tubes are new and need a burn in it won't hurt too much.
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Only thing I would add is that I use a 20-20 test tone instead of actual music. If you don't have a tone generator you can download test tones as mp3s and burn a cd. Seems to work better for me than regular music. Enjoy.
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Grainger49, I just finished making a pair of these contraptions for the crossover caps I want to burn in. My ever-curious girlfriend asked if the big blue ClarityCaps were batteries. That's when it dawned on me that they are, in fact, high voltage batteries. They're rated at 630vdc which got me thinking about how I plan to discharge them after several days of cooking. In tube amps, I usually see drain resistors used for this purpose. How do you recommend dealing with "hot caps" after cooking?
Many thanks for any suggestions.
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I have used a similar technique and it works well. I use alligator clips instead of soldering and banana plugs. And I use a 20-20 test tone as well. I also use my home theater amp to do this. Gives me 8 channels to burn in on (has dual zones). Have also used small desk top systems with integrated CD players.
I also have bleeder resistors with alligator clips soldered on them to clip on to caps to discharge them. Come in very handy and have used them more ofter than I thought I ever would.
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Thanks for your reply ssssly.
How many ohms is the resistor you use for bleeding? And what's the wattage?
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Grainger49, I just finished making a pair of these contraptions for the crossover caps I want to burn in. My ever-curious girlfriend asked if the big blue ClarityCaps were batteries. That's when it dawned on me that they are, in fact, high voltage batteries. They're rated at 630vdc which got me thinking about how I plan to discharge them after several days of cooking. In tube amps, I usually see drain resistors used for this purpose. How do you recommend dealing with "hot caps" after cooking?
Many thanks for any suggestions.
Yes, they look like and kind of act like batteries. The audio signal, which passes through the capacitor, is AC. What you are concerned with is a buildup of DC. But... there should be no DC on the output of your amp. If there were you would destroy your speakers. So after the burn in, whether you use sweep tones or music, there will be no residual charge. Check with your meter set on DC volts after you are through.
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Grainger is of course correct. There should be no DC.
Being a bit overly cautious myself I use a 220k/2W. The bigger the resistor the faster it will bleed down a cap. So for this purpose the bigger the better.
Of course if you check it with a meter and there is no DC there is no need.
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Many thanks for your replies!
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The bigger the resistor the faster it will bleed down a cap.
In terms of resistance, the opposite is true. The smaller the resistor value, the faster the cap will discharge through it. In terms of physical size, which has mostly to do with power handling, it only matters that the resistor is big enough that it won't overheat during the discharge process. A 10K ohm 1W or 2W is typically what I use.
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I always bleed down big caps with my meter clipped on. That way I know how much juice is still in there. I have been bit too many times.
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The bigger the resistor the faster it will bleed down a cap.
In terms of resistance, the opposite is true. The smaller the resistor value, the faster the cap will discharge through it. In terms of physical size, which has mostly to do with power handling, it only matters that the resistor is big enough that it won't overheat during the discharge process. A 10K ohm 1W or 2W is typically what I use.
That's what i get for posting way too early in the morning. Intended meaning was the higher the rated wattage not the larger the resistance.
220k is definitely overkill for just about any cap. Was a combination of what I had on hand and the fact that I needed to bleed some huge caps. Will work will just discharge slower. Still generally talking about seconds.
If I remember correctly the actual formula for bleeders is R = t(in sec) / ( 5 * C ). Someone please correct me if I am wrong.
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If I remember correctly the actual formula for bleeders is R = t(in sec) / ( 5 * C ). ...
That will take the voltage down to about 0.6% of the original voltage, if you ignore dielectric absorption. Many caps have enough DA to bring their voltage back up a bit after discharging so be careful.
Also, t is in seconds if R is in ohms and C is in farads - if you use uF (microfarads) the actual time will be literally a million times longer. It's always a good idea to check with a voltmeter :^)
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Hi
I do really dont, have an amp that i want to use for this. Could i not just have the crack powered on for a few days? And use the stock tube for that?