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

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10/15/2000 3:36 PM

Daver

Re: Anybody added reverb to their D'Clone...? Steve,   The signal goes through a mixing stage just like a Blackface reverb circuit. 1/2 a 12AX7 for reverb recovery and 1/2 for mixing. After the mixing stage there is a .1uf cap from the plate, then a series 220k resistor then a series .022uf feeding the phase inverter. I realize either cap and/or the resistor could be eliminated, but this combo sounded best. If the overdrive is too muddy, dropping the .1uf cap to .047uf or so makes an audible difference. Again, mine uses a little more negative feedback in the preamp, so the signal is probably not as hot as some. It works in this amp, YMMV.   Daver

 

10/16/2000 1:34 AM
JaySG	"Tweed mixer" could be more like the input to a 5E8-A:   Parallel triodes with a common plate resistor and separate cathode RC's. Dry input into one grid, and reverb input on the other.

 

10/16/2000 1:59 AM

Steve A.

Jay:         Thanks! So the two signals (after the twin triodes) are summed up with a pair of 100k resistors going to the .02uF coupling cap. I was wondering about using a single- or dual-ganged linear pot to blend the two signal... but you'd need to add in blocking caps ahead of the pots to keep DC off the pots.         So if you didn't want to add any more gain to your amp, I guess you could wire up the two triodes as cathode followers- right? Might be a fun experiment to try...     Steve Ahola

 

10/16/2000 2:21 AM
JaySG	If you want gain, you can use one common plate resistor for both. If you want a mixed cathode follower, I suppose one common cathode resistor would mix the signals. I'm reaching here...oh Randall...

 

10/16/2000 4:35 AM
Bruce	I think the dry and wet signal is mixed across the single anode resistor and coupled with a single cap to the next stage, Steve.   Kevin O'Conner writes about this in one of his books.   Bruce

 

10/16/2000 3:58 PM

Gil Ayan

OD Reverb Architecture quote: "Gil:         By "tweed mixer" you mean like the pair of 270k resistors that sum up the two channels in a 5F6A bassman?"     No Steve, not at all. This is what the amp basically looks like: after the preamp volume control, the signal is tapped and fed to a completely separate gain stage. At the output of that stage there is a send control which feeds a parallel tube arrangement (just like Fender's), which is the reverb driver.     On the output side, there is a recovery stage, pretty much like Fender's as well. The output of that is fed to a "tweed mixer," which is a two-stage arrangement. The two gain stages have a comon cathode resistor but different plate loads. One side gets the dry signal and the other the wet one.     If you have been counting tubes thus far, you will have come up with a grand total of 3 extra tubes for the reverb.     Gil

 

10/16/2000 5:17 PM

Steve A.

Gil:         Jay had already pointed out the Twin 5E8-A schematic which uses a "tweed mixer" for the inputs of each channel...         So the "different plate loads" would be used to adjust the balance between the Dry and Wet signals... the 5E8-A schematic shows a pair of 100k plate resistors— methinks that you would lower the value of one of them to lower the gain (rather than raise the value to boost the gain)... or do I have that backwards?     --Thanks!     Steve Ahola     P.S. So does Randall have an article explaining how the "tweed mixer" works and how to fine tune it?

 

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