Switching tubes

nicknuisance · 04-29-2007, 06:14 PM

I recently sold my 6505 and bought a Mesa Nomad 45, and shortly after buying it from the dude, a couple of the tubes went out, so I decided to order some new JJ preamp and power amp tubes. The question I have is: can I just pull the power amp tubes and pop in the new ones? I know I can with the preamp tubes, but never had to replace power amp tubes.

Heads up!

OzzyC · 04-29-2007, 07:16 PM

The short answer is yes. But, it's also important to to put the quietest tubes in the earlier stages, to keep the signal to noise ratios optimal.

nicknuisance · 04-30-2007, 08:27 AM

So I replaced the Mesa preamp and power amp tubes with JJ's, and when i go to turn it on from standby, I hear some crackle and hiss here and there. What's the deal?

Popsyche · 04-30-2007, 08:48 AM

I'm not that familiar with the amp, but have you set the bias on the power tubes? Search for bias on the site here for endless discussion on this point.

OzzyC · 04-30-2007, 03:32 PM

Quote:

Originally Posted by Popsyche

I'm not that familiar with the amp, but have you set the bias on the power tubes? Search for bias on the site here for endless discussion on this point.

I'm quite sure Mesas have a hard wired bias.

Bartok · 04-30-2007, 04:29 PM

If the amp has auto-bias, just change, if not, you need to do it manually with a multimeter. Check the manual, it'll at least tell you whether it auto-biases or not

nicknuisance · 04-30-2007, 04:31 PM

Quote:

Originally Posted by Bartok

If the amp has auto-bias, just change, if not, you need to do it manually with a multimeter. Check the manual, it'll at least tell you whether it auto-biases or not

So earlier after switching the tubes, I read the manual for the first time in a while, and all I had to do was put it in standby, then back, and poof! Perfect. Thanks for the heads up.

budda · 04-30-2007, 06:42 PM

how does it sound with those JJ's in?

nicknuisance · 04-30-2007, 06:47 PM

I ordered a matched quad of JJ el34s, 3 high gains for v1, v2, and v3, standard for v4, and a balanced pi tube for v5. It beefed up my gain a bit, and sounds dreamy. The cleans break up a little earlier, but doesn't bother me a bit. First time to use JJs, so worked out great.

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04-29-2007, 06:14 PM	#1
nicknuisance Master Shredder Join Date: Feb 2007 Location: Austin, TX Posts: 272 Thanked: 6 Feedback Score: 3 reviews	Switching tubes I recently sold my 6505 and bought a Mesa Nomad 45, and shortly after buying it from the dude, a couple of the tubes went out, so I decided to order some new JJ preamp and power amp tubes. The question I have is: can I just pull the power amp tubes and pop in the new ones? I know I can with the preamp tubes, but never had to replace power amp tubes. Heads up!

04-29-2007, 07:16 PM	#2
OzzyC :ubersquint: Join Date: Sep 2006 Location: USA Posts: 3,398 Thanked: 17 Feedback Score: 2 reviews	The short answer is yes. But, it's also important to to put the quietest tubes in the earlier stages, to keep the signal to noise ratios optimal. You've got your head down You've got your eyes closed You look so pitiful now Your body encrusted with ash Breath heavy with toxins Hair singed and matted Clothes frayed and burnt You are left with nothing

04-30-2007, 08:48 AM	#4
Popsyche Beer Sewer Join Date: Mar 2006 Location: Bethlehem, PA Posts: 5,108 Thanked: 224 Feedback Score: 1 reviews	I'm not that familiar with the amp, but have you set the bias on the power tubes? Search for bias on the site here for endless discussion on this point. If electricity comes from electrons, does morality come from morons? www.myspace.com/wfkoehleriii http://mysite.verizon.net/vzeo7bjr/index.html

04-30-2007, 06:42 PM	#8
budda Guiterrorizer Join Date: Jan 2007 Location: London ONT Posts: 18,906 Thanked: 174 Feedback Score: 1 reviews	how does it sound with those JJ's in? _______________________ J S Moore pickups: www.tonefordays.com Rock on!

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04-30-2007, 08:27 AM	#3
nicknuisance Master Shredder Join Date: Feb 2007 Location: Austin, TX Posts: 272 Thanked: 6 Feedback Score: 3 reviews	So I replaced the Mesa preamp and power amp tubes with JJ's, and when i go to turn it on from standby, I hear some crackle and hiss here and there. What's the deal?

04-30-2007, 04:29 PM	#6
Bartok ss.org Regular Join Date: Mar 2007 Location: Leeds UK Posts: 265 Thanked: 3 Feedback Score: 0 reviews	If the amp has auto-bias, just change, if not, you need to do it manually with a multimeter. Check the manual, it'll at least tell you whether it auto-biases or not

04-30-2007, 06:47 PM	#9
nicknuisance Master Shredder Join Date: Feb 2007 Location: Austin, TX Posts: 272 Thanked: 6 Feedback Score: 3 reviews	I ordered a matched quad of JJ el34s, 3 high gains for v1, v2, and v3, standard for v4, and a balanced pi tube for v5. It beefed up my gain a bit, and sounds dreamy. The cleans break up a little earlier, but doesn't bother me a bit. First time to use JJs, so worked out great.

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