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Hoffman Amps Forum image Author Topic: One tube reverb in a Pro 6G5-A  (Read 2803 times)

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Offline punkykatt

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One tube reverb in a Pro 6G5-A
« on: October 20, 2016, 09:46:31 pm »
Hey Guys,  I have a client that wants me to install a one tube reverb circuit in place of the normal channel in this amp http://el34world.com/charts/Schematics/files/fender/Fender_Pro_6g5A.pdf  .    Where would be the best place to insert the reverb circuit without messing up the  pitch shift vibrato?  Also which nodes should the reverb tube plates be tapped into? Thanks  in advance for any info and input.    Punky

Offline VMS

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Re: One tube reverb in a Pro 6G5-A
« Reply #1 on: October 20, 2016, 11:13:43 pm »
Maybe this could work and I would probably tap the reverb driver to the phase inverter node or the node A.   :dontknow:




Offline VMS

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Re: One tube reverb in a Pro 6G5-A
« Reply #2 on: October 20, 2016, 11:19:55 pm »
I just realized that my circuit is missing the reverb control pot but that could probably go between .05 cap and 220k resistor without it affecting too much the dry signal.

Offline TIMBO

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Re: One tube reverb in a Pro 6G5-A
« Reply #3 on: October 20, 2016, 11:35:19 pm »

Offline punkykatt

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Re: One tube reverb in a Pro 6G5-A
« Reply #4 on: October 21, 2016, 09:36:58 am »
Great, thanks VMS and TIMBO. 

Offline hesamadman

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Re: One tube reverb in a Pro 6G5-A
« Reply #5 on: October 21, 2016, 10:44:44 am »
Please keep updated on results. I plan to try one tube reverb soon.

Offline punkykatt

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Re: One tube reverb in a Pro 6G5-A
« Reply #6 on: October 21, 2016, 10:35:07 pm »
Yes, I will let you know how I make out.  May take a few days before  I dig into this.
Punky

Offline punkykatt

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Re: One tube reverb in a Pro 6G5-A
« Reply #7 on: October 27, 2016, 02:17:25 pm »
The one tube reverb in place of the normal channel works well.  Not surfabilly level but plenty of reverb for rock and blues.  I used node B for  plate voltage sources cause it was real close by. Pin 1 ended up with 276v and pin 6 ended up with 173v.   I used a 500p input cap, the existing 1M volume pot for dwell and a 2M pot for level control.  I inserted the level control between the .05 cap and the 220k leading to the PI but was picking up DC voltage from the vibrato circuit(scratchy sound on level pot) . I added a .001 cap between the level control and the 220k all is fine.   Thanks to all for your input.  Punky

Offline VMS

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Re: One tube reverb in a Pro 6G5-A
« Reply #8 on: October 28, 2016, 11:49:29 am »
I'm glad it worked.


I inserted the level control between the .05 cap and the 220k leading to the PI but was picking up DC voltage from the vibrato circuit(scratchy sound on level pot) . I added a .001 cap between the level control and the 220k all is fine.


Yes, sorry about that. I totally overlooked the fact there are no caps after the vibrato channel.


Did you notice any difference on the vibrato channel before and after the mod?




Offline punkykatt

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Re: One tube reverb in a Pro 6G5-A
« Reply #9 on: October 28, 2016, 05:08:08 pm »

Did you notice any difference on the vibrato channel before and after the mod?

No difference at all.   What a great sounding vibrato these amps have.    :guitar1









 


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