One Tube Reverb Help

[bandade]

Hi Folks! I just finished my first D-style amp and it sounds great. This is my second amp I've built; the first was an 18 watt Marshall style. The only problem I am still having is that my one tube reverb seams a bit weak. I tried several different designs unsuccessfully and then settled on the one attached. I should note that I am using a 12AT7 rather than a 12AX7. There is a slight hint of natural sounding reverb when it is turned all the way up but it is way shy of what i was expecting. Any ideas?

Thanks

[ChrisM]

Try a 12AX7
Add a filtering cap after R10
Maybe fiddle with the mix resistor, R1.

This design has worked for me before, sounds good actually, not over the top BF reverb.

[Bob-I]

That circuit looks correct. You could have a weak tank, I've had a few. Do you have another tank?

Another few things to try, the input cap can be increased in size to warm up and strengthen the reverb. You can put a 1M trimmer in place of the 1M grid load and use it as a dwell control to add drive to the input.

[butwhatif]

Use a 12ax7, take a look at a Mesa Mk III reverb scheme--

[Bob-I]

I missed where you were using a 12AT7. Where that can drive the reverb better, the recovery side will not have enough gain.

Also, try connecting a speaker to the reverb send and a dummy load to your main speaker out. You should get a fairly strong signal, although it will be a tad thin because of the small input cap. It's a good test to see if the reverb is actually working.

[txbluesboy]

Change the 100K mix resistor to 220K and use a 12AX7. Thats what I use in my "Texas Blues" amp.

[David Root]

How about a 12DW7? Use the 12AU7 triode to drive and the 12AX7 to recover?

[butwhatif]

I like the send to be 'pre' the efx, i just want reverb of the gtr, and od gtr from the reverb, not a reverb of all my efx. likewise i want the r return to mix back as reverb, and not go into the efx. a parallel arrangement. a single 12ax7 will do nicely. i have way more than i need.

[bandade]

Thanks for the help everyone. My tank is good for sure, its a brand new accutronics. I swapped my 12AT7 from the reverb to the PI and put a 12AX7 in the reverb and it sounds great! I also changed the mix resistor to 220k which improved the sound as well.

I am still struggling with the Pre amp in and out. How have you guys been wiring those? I don't use many if any stomp boxes but I already drilled the holes in the chassis and installed jacks.

Thanks

[Bob-I]

I am still struggling with the Pre amp in and out. How have you guys been wiring those? I don't use many if any stomp boxes but I already drilled the holes in the chassis and installed jacks.

Thanks

Look at the layouts that have been posted in the files sections for wiring on the loop. FYI, stomp boxes don't work well in the loop, they simply don't handle the voltage swing.