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Re: Reverb Ramblings

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10/23/2000 1:47 PM

Re: Reverb Ramblings

Ray,
your ideas about reverb placement are very clear, but "a point of relatively fixed signal level" is not simple to find, for example, in a SLO 100 circuit.

If you tap the reverb send after the lead and clean channel masters you can have a near-constant (about 6 dB max. variation) signal level to work. Before the master the range is very variable, due to gain values (I love a very clear AND a very distorted setting all the time for the two channels).

I don't understand you on this point: the "midrangish" effect from reverb level is a risk in this case (when you tap the reverb post-tone stack and master)? If you cut heavily the mids, for example, your reverb feed is mid-reduced and the reverb return is then pre-EQd (the springs aren't really linear, but...).
This is the same principle of post-send (effect send) on a mixer. A bonus effect: with the post-EQ tap the reverb circuit (tubes, tranny, springs) works only on frequencies you use.

But I feel you have another idea about.
Can you explain a little better for me?
Thanks
m.

10/23/2000 8:14 PM

Marco,

I feel an almost-ideal point exists to install reverb in the SLO 100 circuit; between the effects loop return and V4's input. The effects loop has been attenuated to usable levels, so you would not have to boost the tank return signal up too high to compete with the previous signal level going into V4a's grid. And the volume level here does not change too much (obviously, the instantaneous volume level varies all over the place as you play; I mean the 'ballpark' loudness setting).

I would think that any post-master reverb tap level would (obviously) vary with the setting of the lead and clean master controls. With the way I play my amps, I can tell you that would be a lot more than a 6 dB variation - more like 60 dB. If you always play your amp at a similar level, this may be less of a problem, but I still would not advise designing a reverb circuit this way, with a master-volume-variable 'dwell' (Fender's term). You might well get very little reverb at low volumes, and possible reverb-driver overload and 'spring crash' at high master settings.

A spring reverb is very much a bandpass-filter type of circuit, mainly due to the springs but also to a lesser extent by the electronics (although sometimes an effort is made to widen overall bandwidth by boosting high-end lost in the spring system). You can pre-EQ going into the springs (sometimes a bass-cut is used to reduce muddiness and a treble-cut is used to minimize 'boing'), but I wouldn't expect to hear all that much change in tone at the tank output, especially if the pre-tank EQ change involved deep bass or high treble. If you cut the mids, yes, you will hear that at the output of the tank, but not quite like you would hear it if you did the mid cut post-tank.

I'm not sure about the 'bonus effect' you mentioned. I've just found that when the reverb signal is mixed with the straight signal and then EQ'd, I like the resulting sound better.

Ray

10/19/2000 9:36 PM

Re: Anybody added reverb to their D'Clone...?

"Question on the tweed mixer: could you tap the reverb feed right from the dry input to the tweed mixer?"

That's what occurred to me, but I may end up with a phase problem after reverb and effects loop.

"maybe the amp would sound even better if they weren't running the OD Channel through the reverb splitter circuitry..."

Is the problem caused by running through the Reverb mixer circuit, more of a plate loading issue at the splitter point, or both? With my testing, I didn't have time to narrow down on any specific culprit.

10/20/2000 2:12 AM

Jay:

That's what occurred to me, but I may end up with a phase problem after reverb and effects loop.

    I'm not sure if you can have phase problems with a signal coming back from a reverb tank... although I always wondered about adding a phase switch to a reverb circuit just to see if it does have an effect.

    With an FX loop you very well could have a phase problem because an FX patch can have a definite phase to it (unlike the signal from a reverb tank, except as noted above).

Is the problem caused by running through the Reverb mixer circuit, more of a plate loading issue at the splitter point, or both?

    The load on the plate from the reverb signal is not much— on the input side of the splitter it is a 500pF cap going to a 1M grid load resistor. And I think that you can ignore the plate load factor from the other side of the 3M3/10pF splitter (the 220k resistor there plus the 470k resistor and 100k intensity pot constitute the grid load for the following stage).

    So I think that the culprit is the 3M3/10pF splitter...

Steve Ahola

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