Trying amp with a tube removed?

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Trying amp with a tube removed?

Postby erikwa on Tue Feb 26, 2002 9:44 pm

I'd need to test my Selmer Thunderbirds ('64) reverb tube (an odd 6BR8?). Is it safe to pull out one tube and put the amp on? The problem is actually that there is one 6BR8, which is mixed with the usual ECC83s, ECC81s and ECC82s... So I need to know if this odd one is the reverb driver tube. I'm not sure that this is the driver, so I might have to take out other tubes one by one to find out and need to know if this is a safe way to do this.<P>Usually Selmers have those usual tubes (ECC...) and sometimes a couple of EF86s. I'm suspecting a miss-replacement here, but I'm not sure. Any ideas why this amp should have a 6BR8? I don't even have a clue what this tube could have replaced!<P>The amp works ok and everything looks fine inside. That one tube is just making me suspicious for some reason... :roll: It's just too odd!
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Re: Trying amp with a tube removed?

Postby mulder on Wed Feb 27, 2002 1:52 am

I know you can swap preamp tubes while the amp is on, so you should be safe with that. <P>I'm not sure about the power tubes, but I wouldn't run power to the amp without those in there myself.
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Re: Trying amp with a tube removed?

Postby erikwa on Wed Feb 27, 2002 5:06 am

Thanks Mulder!<BR>This would be a preamp section "search" only. Just want to see if that 6BR8 is the reverb tube. if it's not - I'm lost...<P>Do any of you own a T-bird? <P>Erik
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Re: Trying amp with a tube removed?

Postby erikwa on Wed Feb 27, 2002 3:21 pm

Doh!<BR>Went shopping today... <P>Here is a nice electronic store in Helsinki that sells NOS and new tubes for "reasonable" prices - well I save post&packing&money transfer fees so it's value for money... <P>So, I bought some spare tubes for the T-bird:<BR>RCA 6BR8 (USA), National Gold Line 12AU7A (USA), National EM84 *magic eye* (Germany) and Tesla 12AX7A (Czech). And then I bought David Bowies "Low" from a record shop next door...<P>And I have another question too:<BR>Is it safe to replace 12AT7 with 12AX7 or 12AU7 in any situation? Even if that would be tremolo tube or reverb driver?
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Re: Trying amp with a tube removed?

Postby Goku on Wed Feb 27, 2002 3:40 pm

<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Originally posted by BlackAmbulance:<BR><STRONG>Is it safe to replace 12AT7 with 12AX7 or 12AU7 in any situation? Even if that would be tremolo tube or reverb driver?</STRONG><HR></BLOCKQUOTE><P>Absolutely! The only difference is how much gain each tube will have.
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Re: Trying amp with a tube removed?

Postby erikwa on Wed Feb 27, 2002 4:02 pm

Thanks Goku!<BR>Now I can get down to it while listening to David Bowie :p
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