Dumbleator question

[talbany]

This is my first post here and would like to thank everyone Gil, Bob, Dogears, Gary etc..., for being so generious in shareing there knowledge and posting pics layouts,etc. I have learned a great deal and am greatful.
Anyway I do have a question concerning where to tap off for the send on the Dumbleator. I have built several 97 style amps with HRM all of which sound wonderfull thanks to the help of this board. I have tried tapping off as per 1997 A2 schem but when I switch to overdrive the boost in signal caused the reverb mix to change providing way too much reverb in the mix. My effects loop is basicially like the one posted on Blue guitar/ schematic heaven (gain stage- cathode follower) I have tried many differant settings on the loop as well as the amp but just cannot find balance between the two. Any help would be appreciated.

[Luthierwnc]

I'm looking at the schematic and scratching my head. The clean master is the problem. When you are using the clean channel and an effect, the clean master acts like an extra send pot, grounding a lot of signal to the effect unless the master is wide open. The OD channel sends a whole lot of signal to the effect.

Two fixes come to mind. The first is to put the loop between the .047 coupling cap and the clean master. That way, the effect gets the same level of signal on either channel. It will be a lot easier to synch the clean master and the drive/level pots on an even playing field. The other idea is to use a universal master rather than the clean.

I think if you can put comparable volts into the reverb, it will be a lot easier to keep the mix in acceptable parameters.

Good luck and post your findings,

Skip

[dogears]

I don't understand the problem.......

I have 4 amps here with built in Dumbleators. All after the master. One is HRM. No issues on any of them!!! They all work perfectly. They all have reverb that works equally well in OD or clean.

Why would it matter if there are two masters??

[glasman]

Anyway I do have a question concerning where to tap off for the send on the Dumbleator.

You can tap before the loop or before the send pot. Remember that the first stage (follower) has a gain of 1 (or a little less).

I have built several 97 style amps with HRM all of which sound wonderfull thanks to the help of this board. I have tried tapping off as per 1997 A2 schem but when I switch to overdrive the boost in signal caused the reverb mix to change providing way too much reverb in the mix. My effects loop is basicially like the one posted on Blue guitar/ schematic heaven (gain stage- cathode follower) I have tried many differant settings on the loop as well as the amp but just cannot find balance between the two. Any help would be appreciated.

When you say it is basically the same loop, what are the differences? Did you add or remove any components (like maybe the feedback network).

Also take a look at the Reverb-A-Loop schematic in the files section, it might give you some ideas.

Gary

[talbany]

Thanks for getting back with me. Let me clarify, attached is a schematic of a rackmount Buffered tube effects loop. I am not sure where Input J1 is tapped in the HRM topology. Like I said I Tried it as per 1997 but when I switched to OD it drove the reverb too hard. Maybe I am using the wrong buffer.

Tony.

[Luthierwnc]

I should have asked this first but what kind or reverb are you using? A related question is, "what kind of input signal does it call for?" A line-level rack unit is probably around +4 dbv. A stompbox in front of the amp is probably looking for around -25 dbv. Usually the level control will dial this in but we have already looked at the obvious stuff.

FWIW, I made one like Gary's reverb-o-loop but using a 6K6 tube. It works great in the send/return before the phase inverter.

Skip