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View Full Version : 1971 Super Reverb technical journey...

drgonzoguitar
02-04-2009, 04:33 PM
I originally posted about this when this amp was given to me (amp lottery!).

Read here:
http://www.thegearpage.net/board/showthread.php?t=445217

I then got the amp and starting going through some of the issues: Trem inop, reverb inop, freaky dusty tubes, original caps, etc...

http://www.thegearpage.net/board/sho...d.php?t=461354 (http://www.thegearpage.net/board/showthread.php?t=461354)
(blues rock chord crunching at 2:23)

So, I finally had time this week to give her the overhaul she deserves.

1) Reverb: The tank was bad! I thought I tested it, but I must not have. :dunno Anyways, I had a 3 spring Accutronics of the same impedance to replace it with. Reverb -- good!

2) Vibrato (aka Tremolo): Footswitch broken and a loose cap! I replaced the plug, and all is good.

3) New tubes through the entire amp. Old tubes...saved for a rainy day.;)

4) Removed ground switch (safety issue...thanks for pointing this out hasserl).

5) Added "Soul Control" - additional 5k on NFB for more response. :BluesBros

6) Changed Hum Balance to Bias Adjustment

7) Cap job


Final result? Not the best recording (a cheap mic into my Tascam DR-1 field recorder), but you get the idea....

http://soundclick.com/share?songid=7307230

I used a Strat with a humbucker in the bridge. The amp is: Vol 8, Treble 3, Mid 10, Bass 1. The amp is attenuated -12db via 2ohm Hotplate

____________________________________________
Things I am thinking about doing:

1) Changing the pre-PI coupling caps to limit bass response. It is a bit chunky, even with Bass on 1!

2) Leaving the PI values at the SF (per recommendation of Hasserl). I did not change them and I am pretty sure I will not.

Other than that...I am really happy with the amp. I cant wait to gig with it this weekend!
drgonzoguitar
02-05-2009, 07:11 PM
One bump for other nerdy tech readers.....
RGB
02-06-2009, 09:00 AM
Question...is it ok to leave the ground switch in line as long as the 3 prong has been done?

...and what does the switch do at that point? Should it be in a certain position for safety?

I added the 3 prong and removed the "death" cap, but I left the switch in and just wired the hot and neutral to the same spots on the ground switch.

Should I fix this?

Nice work, by the way!
drgonzoguitar
02-06-2009, 06:21 PM
I removed my ground switch because if the fuse blew, I did not want any AC hanging out around the switch area...matter of safety while working on it.

There is no point of having the switch in there once you remove the cap. I have my switch in the chassis still, just removed from the circuit. The AC comes in straight to the power and fuse now.
davemccarthy707
02-06-2009, 06:45 PM
Awesome tone. I have two 69's both of which are blackfaced and have the nfb mod. These are my alltime favourite amps!!!
jay42
02-06-2009, 06:56 PM
The ground switch hole is a good place for the 'soul control'.

If you get blocking distortion on low notes & power chords when cranked, lower the post PI pass caps -- different than trying to limit bass pre-PI.
drgonzoguitar
02-07-2009, 12:18 AM
The ground switch hole is a good place for the 'soul control'.

If you get blocking distortion on low notes & power chords when cranked, lower the post PI pass caps -- different than trying to limit bass pre-PI.

The ground switch is a good spot for the soul control, but I decided to remove the extra output jack and place it there. It keeps the layout (which can be messy in some of the odd circuit choices) a little cleaner, IMO.

I might consider the post-PI option! When I gig with it tomorrow, I'll have a better idea what fine tuning needs to be done. Thanks for the idea!