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Posted: Thu Nov 04, 2010 8:56 am
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Don't worry suddentwigs, if it hasn't already sparked, I'm sure that you are fine. :) Those Sovtek tubes are pretty sturdy, and can run just as hot as the JJs. I actually prefer the Groove Tubes, which were largely Sovtek tubes anyway. 8)

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Posted: Thu Nov 04, 2010 9:25 am
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So, Shimmilou, to clarify - if the plate dissipation rating of my new tubes is the same wattage or higher than that of the previous ones, I don't need to worry about blowing them? Providing it was biased correctly to begin with, of course. Correct?


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Posted: Thu Nov 04, 2010 10:05 am
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Well, that's part of it. Different tubes will sometimes run at a different Plate dissipation at the same bias setting. If the bias is set for the JJ tubes, say at 14 watts idle, and you put in Sovteks, they might idle at 16 watts, or more or less watts, hence the need for biasing each set of tubes for your desired performance. But usually there is not enough of a difference that it would hurt the tubes or the amp, but it is possible. Like you said; if it was right to begin with...then it's probably close enough not to worry. The tubes that run hotter temperature (more watts) will tend to have shorter life, but in the short term, they won't harm anything. They should at least last long enough for you to learn how to bias them. :)

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Posted: Thu Nov 04, 2010 10:56 am
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Using the proper tools such as a bias probe will go a long way toward doing this safely.----Bluesky

When mesure bias, even with a bias probe, you need to know, with volmeter, how many volts you have at your power tubes plates. You can't trust schematic. This test is for poeple who know what they are doing, the voltage there is lethal.


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Posted: Thu Nov 04, 2010 1:08 pm
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stratele52 wrote:
Using the proper tools such as a bias probe will go a long way toward doing this safely.----Bluesky

When mesure bias, even with a bias probe, you need to know, with volmeter, how many volts you have at your power tubes plates. You can't trust schematic. This test is for poeple who know what they are doing, the voltage there is lethal.


Ummm, did you bother to read my earlier post and look at the bias probe I use and recommended? Here it is again just in case you didn't:

http://www.amp-head.com/product_info.ph ... ucts_id=70

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Posted: Thu Nov 04, 2010 1:15 pm
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Oooops !!! What a nice bias probe. I never see that kind of marvelous tool.

Thank's for giving me the hints.

bluesky , I appreciate you on the forum.


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Posted: Thu Nov 04, 2010 1:34 pm
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stratele52 wrote:
Oooops !!! What a nice bias probe. I never see that kind of marvelous tool.

Thank's for giving me the hints.

bluesky , I appreciate you on the forum.


Sorry if I came across a little harsh. Its a dull, pouring rain day in Virginia and I just want to go home and play my guitar. 8)

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Posted: Thu Nov 04, 2010 1:44 pm
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bluesky636 wrote:
...Sorry if I came across a little harsh. Its a dull, pouring rain day in Virginia.......and I just want to go home and play my guitar. 8)


Sounds like you have a blues song in the making, good blues lyrics.....in the key of E...a 1 anda 2 anda 3....<Strat solo intro>.... :lol: It's cold and rainy here too... :(

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Posted: Thu Nov 04, 2010 2:36 pm
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shimmilou wrote:
bluesky636 wrote:
...Sorry if I came across a little harsh. Its a dull, pouring rain day in Virginia.......and I just want to go home and play my guitar. 8)


Sounds like you have a blues song in the making, good blues lyrics.....in the key of E...a 1 anda 2 anda 3....<Strat solo intro>.... :lol: It's cold and rainy here too... :(


Almost.

My latest assignment from my guitar instructor is to write my own solo for "Stormy Monday". :lol:

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Posted: Thu Nov 04, 2010 3:49 pm
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Rainy day too, here in Québec


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Posted: Fri Nov 05, 2010 3:15 am
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Update - I've now replaced the preamp tubes. This has got rid of most of the problem, however I still have a buzz which appears on low notes, and a more intermittent crackle. Do these sound like the symptoms of improper biasing? Going to give it a proper checkup tomorrow, is that a better place to start than investigating solder joints etc?


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Posted: Fri Nov 05, 2010 6:23 am
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suddentwigs wrote:
Update - I've now replaced the preamp tubes. This has got rid of most of the problem, however I still have a buzz which appears on low notes, and a more intermittent crackle. Do these sound like the symptoms of improper biasing? Going to give it a proper checkup tomorrow, is that a better place to start than investigating solder joints etc?


A buzz on the lower strings sometimes is indicative of crossover distortion caused by improper bias.

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Posted: Fri Nov 05, 2010 12:35 pm
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suddentwigs wrote:
... and a more intermittent crackle.... investigating solder joints etc?


Intermittent problems, usually indicate solder joint problems. I have chased these crackling sounds on a few amps, most often it is usually the preamp tubes and/or solder joint problems. The tube socket solder connections on the circuit board are the first place to check next. But, to be sure, at least check the bias to make sure of what you have. Sometimes, when you aren't sure of the problem, use the process of elimination. You replaced the preamp tubes (new ones I hope), next check the bias setting, then touch up all solder joints on tube socket boards. Next would be to replace the Plate load resistors with better ones. All of these things are important, and each should be checked. :idea:

You can try plugging your guitar straight into the "Power Amp In" on the amp, bypassing the preamp circuit completely (I just tried it on my HRDlx to make sure, it is OK). The amp volume must be very low, say 2, clean channel, reverb and presence all the way down, turn up guitar volume very slowly to prevent loud feedback. Check to see if you still have the crackling sound. You can turn the amp volume up some, just avoid feedback, it can get out of hand. If the crackling is gone, the problem is definitely in the preamp circuit (tubes, solder joints, Plate resistors). If the crackling is still there, then check the solder joints on the big tube socket connections (output tubes). :idea:

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Posted: Fri Nov 05, 2010 1:15 pm
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Here's how to check the tube socket joints. Get a large magnifying glass and look at the tube socket solder joints on the board while gently wiggling the tubes. If the joint show a fracture touch it up with a soldering iron. It's pretty simple really. Check all the tube sockets while you're at it. Solder joint problems are legendary with the HRD series amps. Don't try to over stylize the problem. Most times on these amps it's either a solder joint problem or a tube problem. Be careful touching up the joints. The traces are delicate on these amps and lift very easily.

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