Valve type (Marshall AVT50) - Jemsite
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post #1 of 15 (permalink) Old 10-08-2009, 02:13 PM Thread Starter
 
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Valve type (Marshall AVT50)

Hello fellow Jemsiters, haven't been around here in a while!

Quick question... anyone know what type of valve is used in the Marshall AVT50? Mine is three years old now and still going fine with the original valve but I should really look for a spare/replacement just in case... bit of a problem though since I don't know what type of valve it uses. I know, it's sacrelige, blasphemy etc., but I'm not clever with amps... great with guitars, but not amps! To make matters worse I don't have the instruction manual and the shop I bought it from - a good one at that - went bust a while back so I'm a bit stuck.

If anyone knows (I'm sure someone will) please advise.

Cheers

'87
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post #2 of 15 (permalink) Old 10-08-2009, 03:58 PM
 
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Re: Valve type (Marshall AVT50)

Hi, I believe it's fitted with a ECC83 aka 12AX7 preamp tube...


Regards,
Nelson
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post #3 of 15 (permalink) Old 10-08-2009, 05:52 PM
 
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Re: Valve type (Marshall AVT50)

I've got an AVT20, and it's definitely a 12AX7.

I've swaped a few tubes in and out of it, and never really heard any discernible difference, so don't get too wrapped on on which 12ax7 to use.
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post #4 of 15 (permalink) Old 10-08-2009, 06:15 PM
 
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Re: Valve type (Marshall AVT50)

Wow, tubes. What a can of worms. IMHO even a different 12ax7 can make a big difference. I'm not familliar with the amp, but is this the only tube in it? Google 12ax7 vs 12at7. You'll get a ton of info about how one little tube can cause a stir. You can swap out any other 12a*7 tubes (X,T or Y) but manufacturers don't like to say so. Spend a couple of bucks and get e few different kinds and brands. Heck there cheap as few dollars. Play 'em and swap 'em out! Have fun. I'll bet you find one that you prefer. Keep in mind some will cut your ouput a little, but not much in some amps.
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post #5 of 15 (permalink) Old 10-09-2009, 04:32 AM Thread Starter
 
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Re: Valve type (Marshall AVT50)

Right, 12AX7. Thanks folks.

'87
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post #6 of 15 (permalink) Old 10-09-2009, 11:40 AM
 
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Re: Valve type (Marshall AVT50)

'87, check this out...


http://www.manualnguide.com/download...-handbook.html

Might be of some help


Geoff
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post #7 of 15 (permalink) Old 10-09-2009, 07:57 PM
 
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Re: Valve type (Marshall AVT50)

Quote:
Originally Posted by forest4 View Post
Wow, tubes. What a can of worms. IMHO even a different 12ax7 can make a big difference. I'm not familliar with the amp, but is this the only tube in it? Google 12ax7 vs 12at7. You'll get a ton of info about how one little tube can cause a stir. You can swap out any other 12a*7 tubes (X,T or Y) but manufacturers don't like to say so. Spend a couple of bucks and get e few different kinds and brands. Heck there cheap as few dollars. Play 'em and swap 'em out! Have fun. I'll bet you find one that you prefer. Keep in mind some will cut your ouput a little, but not much in some amps.
They'll make a difference in an all tube amp, but the Valvestate is a hybrid, and the tube in them doesnt really do that much.
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post #8 of 15 (permalink) Old 10-10-2009, 10:47 AM
 
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Re: Valve type (Marshall AVT50)

I did a little checking on that amp, and you are right. Once you start messing with tubes, your cursed for life!
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post #9 of 15 (permalink) Old 10-10-2009, 11:50 AM
 
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Re: Valve type (Marshall AVT50)

It's a Marshall labeled ECC83 in these amps. Russian made tube.
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post #10 of 15 (permalink) Old 10-14-2009, 04:52 AM
 
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Re: Valve type (Marshall AVT50)

Sorry to hijack the thread for a moment, and I've got a Marshall AVT150 on the way. I was wondering:

Say I was at sound check just before a gig and the valve stopped working. Could I quickly pull out a spare and replace it myself in a short time or is there more to it than that?

Thanks in advance.
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post #11 of 15 (permalink) Old 10-14-2009, 11:17 AM
 
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Re: Valve type (Marshall AVT50)

Should be a quick and easy replacement, as it's only a preamp tube, not a Power Tube.

I replaced mine several times experimenting with different tubes by simpy powering down, waiting for the tube to cool enough to handle, pop the new tube in, power up. Repeat as necessary.

The AVT series is a hybrid amp. Meaning it is both tube and solid state. It has a tube pre-amp section, and a solid state Power Section.

This makes tube replacements much easier, as it is a single 12ax7/ecc83.
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post #12 of 15 (permalink) Old 10-15-2009, 05:15 AM
 
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Re: Valve type (Marshall AVT50)

Quote:
Originally Posted by GLG421 View Post
Should be a quick and easy replacement, as it's only a preamp tube, not a Power Tube.

I replaced mine several times experimenting with different tubes by simpy powering down, waiting for the tube to cool enough to handle, pop the new tube in, power up. Repeat as necessary.

The AVT series is a hybrid amp. Meaning it is both tube and solid state. It has a tube pre-amp section, and a solid state Power Section.

This makes tube replacements much easier, as it is a single 12ax7/ecc83.
So if the ECC83 inside it were to die, I could just wait until it's cool, then pull the replacement out and change it as if I were changing a lightbulb?

Cool Thanks
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post #13 of 15 (permalink) Old 10-15-2009, 09:31 AM
 
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Re: Valve type (Marshall AVT50)

Yep. good analogy with the light bulb.
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post #14 of 15 (permalink) Old 10-17-2009, 12:08 AM
 
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Re: Valve type (Marshall AVT50)

I have an AVT50H and I've never replaced the tube. I've had this thing years. Is it something i should look into doing? Are there many different types usable?
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post #15 of 15 (permalink) Old 10-17-2009, 09:13 AM Thread Starter
 
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Re: Valve type (Marshall AVT50)

Only if the sound starts to go bad, e.g. crackling, popping, various other weird noises. Usually means that the tube's on the way out.

'87
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