Best way to calm the reverb on my AB763?

[SILVERGUN]

I have laid out the AB763 circuit on the breadboard (6L6 single channel with reverb/ no trem) and it sounds great, BUT there's no reason to go past 2-3 on the reverb pot.

Is there a tried and true mod that will give me more useable range from that pot, before I go trying everything?
It sounds like there may be too much gain from the paralleled 12AT7 pushing the signal into the tank too hard?? 
Would it be helpful to add send/return or Reverb vol. controls?

Any suggestions will be helpful, so my ears don't have to take the brunt of the tweaking....thanks in advance 

[floyd]

Use an audio taper pot , instead of linear , and/or use a lower gain driver tube.

[quayhog]

you could also try a 12AU7 as the driver tube.   

[Willabe]

you could also try a 12AU7 as the driver tube. 

Yep, some guys really love the sound of the verb with a 12AU7 for the driver tube.

You could also use a 1M pot instead of the 1M grid R for the driver tube.



                        Brad       

[tubenit]

You could also use a 1M pot instead of the 1M grid R for the driver tube.

That is what I'd do.  1M dwell pot on maybe "5".

With respect, Tubenit

[eleventeen]

I'll have try a 12AU7 for the verb driver. Bigger plates, maybe it'll run cooler...generally not a very useful tube due to its low gain. Because I hacked an organ to pieces recently, I have a delightful assortment of 36 of them. Bleh.

[SILVERGUN]

Unfortunately, I don't have any AU7s here or I would've tried it...

I clipped a couple different value resistors across that 1M and got all the way down to 100K before it really made a huge difference, so yeah, that did what I asked for, and made the pot more useful.....but, I'm not sure if it's enough of a difference, so I'll order in an AU7 and report back

Maybe it's a little less push that I'm looking for, OR some control on the wet side

I like the reverb on 2 when I'm playing softer or with the volume on my guitar down, but when I turn up or play harder the tank seems to have lots of "ring" to it

I'm sure this has been discussed hundreds of times before, so I apologize in advance for the repetitive nature of my posts

[tubeswell]

Change the voltage divider in the wet/dry signal blend point. If you reduce the 3M3 to say 2M7 or 2M2, you will reduce the wet signal and increase the overdrive. Otherwise try reducing the 220k and/or the 470k and/or the resistance of the reverb level pot

[Ed_Chambley]

A dwell on a fender with reverb is an absolute IMO. Even if using a 2 spring.  No mention of the tank you are using.  This has a great impact.  For instance, an original Gibbs 2 spring tank sounds different than the Accutronics.  The bottom cover on the tank will change the spring vibration as well.  Check the reverb tone with the tank open then put a flat cover on it and then try with the cover raised, like the stock tank came.  Cardboard that is double think down the edges leaving the ends open.  You can also dampen the springs using the packing foam or even masking tape and it will darken the sound and decrease dwell.  Increasing spring tension will sharpen the tone and decrease the dwell.  Many things you can do to the tank, but it seems most jump right to the circuit.  Just thought I would mention this as it is a way to change the tone.

Also, if you are accustomed to high gain tones, reverb will seem strong.  Sure you can get more control with an AU7, but I don't really prefer it, but many do.  You can also loosen the screw on the knob and make 2 become 5.

If you have a 3 springer tank it will get messy quickly without a dwell.

[loogie]

Change the voltage divider in the wet/dry signal blend point...

You could make it adjustable and decide with your ears.

[SILVERGUN]

No mention of the tank you are using

I used the MOD 4AB3C1B tank as a result of some reading I had done prior to purchase.....most agree they are very wet sounding
It is mounted open side down on a piece of 5/4" decking laid on my bench,,,,and yeah, I was considering putting some of the packing foam back in it...
I do like the dwell of the reverb, it's just the clang of the spring when I lay into it that is most annoying.......I'll try some of those spring suggestions before I mess with the circuit

Also, if you are accustomed to high gain tones, reverb will seem strong.  Sure you can get more control with an AU7, but I don't really prefer it, but many do.

Well,,,,, this amp is all about crystal clean for me.....but, I'm noticing that I'm gonna need some lower output pickups to accomplish that
When I turn the guitar volume all the way up, I seem to very easily overload the front end, and I was going to address that in another thread
I will definitely try the AU7 driver as part of my normal "over-tweaking", and to try to drop some overall gain.....and I'll be looking at the gain of the recovery triode

Change the voltage divider in the wet/dry signal blend point. If you reduce the 3M3 to say 2M7 or 2M2, you will reduce the wet signal and increase the overdrive. Otherwise try reducing the 220k and/or the 470k and/or the resistance of the reverb level pot

More good stuff....thank you

[alerich]

Use an audio taper pot , instead of linear.

This ^^^. I have done this several times on several different Fender amps and it works great. I have never understood why Leo used a linear pot for this function - he should have just used a switch. It's an easy mod and it solves the problem.

[rafe]

12AU7's they are the way to go for my Vibroverb....

[PRR]

Cut out both cathode caps.

[jojokeo]

My 2cents: The dwell controls how much signal goes into the reverb pan. So the dwell control affects how much after ring you get from the reverb pan.

The newer Acutronics reverb pans are more sensitive than the original Gibbs/Hammond pans so when you use them in a vintage amp you get a bit more dwell than the original pan would have given. What reverb pan type are you using SG? This will help confirm the above statement.

[SILVERGUN]

What reverb pan type are you using SG?

I used the MOD 4AB3C1B tank as a result of some reading I had done prior to purchase.....most agree they are very wet sounding

I'll get back to it Mon. night and I've decided to go ahead and try everything (one at a time) that you guys have given me here and try to take accurate notes on how I perceive the differences,,and post the results to try to give back a little  ......AU7's are on the way

[SILVERGUN]

OK, so I didn't get as much valuable info. for you guys as I would have wanted, but I did get the solution to my problem....
After changing out some component values pre and post tank,,,I wound up removing the cathode caps on the driver and recovery tubes (per PRR) and it had a HUGE effect on the amount of reverb in the signal...and I lost a little too much depth
I had also tried "packing in" the springs (with foam and/or cotton ball), but couldn't find a happy medium where I didn't kill it completely.....it got rid of the clanginess, but also got rid of too much dwell
SO, I went back and tried it with one or the other bypassed,,and I found a perfect solution by only removing the cap from the driver tube
For me, it got rid of a lot of the "excess artifacts" in the background of the reverb, and gave me a nice, clean, controllable dwell, that has way less spring ring/clang in it,,,,and confirms my idea that I was looking for a little less push into the tank
I returned all other changes to stock values and I was very happy with the end result.....this tweak, combined with a small reduction in preamp gain, has brought me to a point where I can move forward with this amp.
Thanks again for all of your suggestions!

[jojokeo]

Sweet! All good update info. Did you try the 12au7? What did you end up using?

[SILVERGUN]

Did you try the 12au7? What did you end up using?

Yeah,,,and honestly didn't notice a huge difference....still made it ring too much
Tried it without the cathode cap and it was OK, but I put the AT7 back in with the cath. cap still off and it just made me smile.....it was perfect,,, for me

So now it just looks like this

[Willabe]

I used the MOD 4AB3C1B tank as a result of some reading I had done prior to purchase.....most agree they are very wet sounding

I just noticed this. That tank is the long decay. That will give more ringartifacts.

A lot of guys prefer the medium decay for this reason, you should try one and see if it helps.


                Brad        

[jojokeo]

So now it just looks like this

It looks so innocuous!!!

[SILVERGUN]

I just noticed this. That tank is the long decay. That will give more ringartifacts.
A lot of guys prefer the medium decay for this reason, you should try one and see if it helps.

It looks so innocuous!!!

Yeah,,,,next time I order one i'll try a different tank, and put the cap back on there to hear the difference

Thanks