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Post subject: Fender Bassman '59 Reissue tubes.
Posted: Sun Apr 11, 2010 6:01 am
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Hey guys, I just put a new '59 Bassman Reissue on layaway. I have had a variety of amps in the past but when I played this thing, I was blown away! It's got that chug for rhythm guitar that I have always wanted. Of course, with a bigger amp like this with no master, I do fear that lower volume gigs will be an issue. I have read that some are swapping out the V1 12ax7 for a lower power 12ay7 to get the preamp volume down so that the 6L6's can do their thing in the power section. Any thoughts on this? I really like the sound of this amp the way it is but might consider a V1 change if it doesn't change the overall sound of the amp. Also, would this hasten the demise of any other parts in the amp?

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Greg :o


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Posted: Sun Apr 11, 2010 6:28 am
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12AY7 will give you about 50% less gain, 12AU7 will even give you 80% less gain. It may have a drastic impact on your sound, will be cleaner, not as hot. Maybe try a 12AT7, this way you wont lose as much.

I think the original Bassman had 12AY7 but the plate resistor were 1/2 watts, the reissue is 1/4 watts. Not sure if that smaller resistor can handle it.

I would try and see if you like the sound of the 12AY7 first. If you do, replace that 1/4 resistor with a 1/2 for safety.


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Posted: Sun Apr 11, 2010 11:44 am
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I would check out some NOS Jan Phillips 6l6wgb tubes.They tend to breakup sooner.


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Posted: Mon Apr 12, 2010 9:06 am
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I would try and see if you like the sound of the 12AY7 first. If you do, replace that 1/4 resistor with a 1/2 for safety.[/quote]

Would that void the warranty?


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Posted: Mon Apr 12, 2010 9:26 am
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It would most definitely void the warranty but wouldnt installing tubes that are not recommended do that too?


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Posted: Mon Apr 12, 2010 9:36 am
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atolleter wrote:
It would most definitely void the warranty but wouldnt installing tubes that are not recommended do that too?


Well, that i a good question but I have heard that there are mention of tube changing in "the manual", but I have not been able to find a record of that yet.


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Posted: Mon Apr 12, 2010 9:44 am
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Or keep it unmolested until the warranty runs out :)


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Posted: Mon Apr 12, 2010 12:57 pm
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I'm going to get a Bassman reissue too, and in my research I've heard of many people putting a 12AY7 in V1. This is the first time I've heard about plate resistors possibly not being up to the task. Good to know.

What I was planning on doing with my Bassman when I get it is to replace the 5AR4 rectifier with a lower wattage 5R4 and rebias the 6L6's. It appears a lot of people have done that to their Bassmans with no ill effects. Any opinion here on switching to a 5R4?

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Posted: Mon Apr 12, 2010 3:01 pm
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Ditto on the 1/2 watt resisters, the 12AY7 will smoke it.

My reissue wasn't up to the task and it cost me a few hours of repairs.

on the other hand, after the warranty runs out, a small mod and then try that 12AY7.

The clean and power tube overdrive sounds are unbelievable.

My Clark Piedmont (a 59 bassman clone) is set up with the original circuit, 12AY7 in v-1 and 5881 power tubes.

Nothing in this world sounds better !!!!

12AX7's are just too easily overdriven and noise makers, its that smooth power tube distortion that sounds like liquid gold, the 12AY7 lets your power tubes get there before the preamp is buzzing like a bee hive.

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Posted: Tue Apr 13, 2010 12:35 pm
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blues bondsman wrote:
Ditto on the 1/2 watt resisters, the 12AY7 will smoke it.

My reissue wasn't up to the task and it cost me a few hours of repairs.

on the other hand, after the warranty runs out, a small mod and then try that 12AY7.

The clean and power tube overdrive sounds are unbelievable.

My Clark Piedmont (a 59 bassman clone) is set up with the original circuit, 12AY7 in v-1 and 5881 power tubes.

Nothing in this world sounds better !!!!

12AX7's are just too easily overdriven and noise makers, its that smooth power tube distortion that sounds like liquid gold, the 12AY7 lets your power tubes get there before the preamp is buzzing like a bee hive.


Maybe there would be times when I would want the 12AX7 tone. Would it be OK to put the 12AX7 back in after switching to 1/2 reistors? Would the tone change or affect the amp in a bad way?

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Posted: Tue Apr 13, 2010 1:37 pm
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Yes you could swap them back and forth after the mod.
the only thing the mod does is keep you from frying the 1/4 watt resistors with the 12AY7.

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Posted: Wed Apr 14, 2010 6:24 am
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blues bondsman wrote:
Yes you could swap them back and forth after the mod.
the only thing the mod does is keep you from frying the 1/4 watt resistors with the 12AY7.


Thanks. But hold on a minute! I just took a peek at the schematic (Fender only has the old version reissue up on this site) http://support.fender.com/schematics/gu ... ematic.pdf and I'm assuming that the 100K ohm plate resistors for V1 are R8 and R9. If so, they are called out as 1/2 watt. Are these the plate reistors and are they actually 1/2 as per the schematic? I don't have a Bassman reissue in front of me yet to check. Did Fender start using 1/4 watt for R8 and R9 for the Bassman LTD?

Thanks.

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Post subject: bassman
Posted: Thu Apr 15, 2010 8:26 pm
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i personally have a bassman, in smaller gigs, this amp wont be a problem.
dont get me wrong, this amp is way too loud for bedroom use.
question, how small are small gigs, im trying to gain perspective.

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Post subject:
Posted: Fri Apr 16, 2010 9:24 am
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Sorry to hijack this thread, but I'm bumping it for my and bluesstrattone's questions.
re: All the talk of 1/4 plate resistors yet 1/2 watt on the schematic. And bluesstrattone's question of perspective of volume - I'm curious about that too.

Thanks.

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