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Post subject: Fender Princeton Reverb Tube Question
Posted: Fri Feb 17, 2012 10:10 am
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Hey,my buddy has a PR and he has a 5y3gt in place of the Gz34 on the tube chart.

He says its all original with exception of the Tesla 6v6 gt's.

Would it hurt to go back to a gz34?

Did fender put 5y3 in even when the chart said otherwise??

The chart says AA764. Its a 1966.


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Post subject: Re: Fender Princeton Reverb Tube Question
Posted: Fri Feb 17, 2012 6:26 pm
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You sure he has a Princeton REVERB and not a simple Princeton? I have an AA764 PR and it comes with the GZ34 rectifier. I believe some transition Princetons (wtihout the 'verb) used 5Y3GT and not GZ34's.

You can use the GZ34 in place of the 5Y3GT provided you check the output tube's idle bias and plate voltages. As the GZ34 puts out much more voltage than a 5Y3GT. Really, if the amp sounds fine with the 5Y3GT, use it. If you want a bit stiffer tone... go to a 6087. It's indirectly heated (slow warmup like the GZ34) and has more mA, but keeps the plate voltage and bias circuit voltage in the same ballpark as the 5Y3GT.

http://www.ebay.com/itm/Strong-GE-Brown ... 1c23c35d8b


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Post subject: Re: Fender Princeton Reverb Tube Question
Posted: Sat Feb 18, 2012 8:27 am
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Yep he has a princeton reverb

I just found it very odd that the Chart would call for a Gz34 but the 'original' 5y3gt was there.


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Post subject: Re: Fender Princeton Reverb Tube Question
Posted: Sat Feb 18, 2012 8:57 am
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I have not seen any PR with 5Y3GT. I've owned two AA764, both had GZ34. Worked on four or five throughout the years. All had GZ34. These are great amps. The reverb and tremolo/vibrato are a bit stouter than the 5U4GB powered AA1164, IMHO. I think it's because of the higher HV and less sag of the GZ34.

Which is lost if you are using a 5Y3GT. Which has less current reserve and lower HV than a 5U4GB. What is the idle bias of this amp? My bet is it on the cold side. Unless some resistors have been changed, along with the rectifier.

You maybe surprised at the tone with a GZ34. I'd get a good used one, as NOS is $$$ and new ones maybe kinda hinky (gotta get buy "selected" Sovtek or TAD). Be sure to check the plate voltage and idle bias after replacing the rectifier, if ou decide to do this swap.

http://www.ebay.com/itm/MULLARD-GZ34-5A ... 5ae5072b57


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