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6G15 reverb unit clone harshness

6/13/2005 10:04 AM
Ric 6G15 reverb unit clone harshness
A while back I finished building a 6G15 reverb unit clone, pretty well true to the original schematic and layout. All the controls work like they should, no excessive hum, but the reverb doesn't sound smooth. It sounds very brittle and almost echoy, like i'm playing my guitar in a long metal hallway. The 6K6 is a NOS RCA, and I've tried swapping out preamp tubes. Reverb tank is an Accutronics long two spring model, with 8 ohm input (4ab3c1b, I believe).  
Any ideas for debugging this guy? It *almost* sounds great...
6/14/2005 12:51 AM

If you duplicated the schematic and layout well then one guess I have for the tonal difference would be the efficiency of the capacitors. Perhaps modern film caps are too harsh with this design. In that case I would think that a top end "bleeder" cap carefully placed would kill the harshness. Have you seen a schem for the reissue reverb? I was surprised to see a bleeder cap in my 1959RI (220pf to ground from the tonestack output). This amp is too brittle without it even though it is acurate to the schematic otherwise.  
What kind of caps did you use?  
Other than that there are two other things I could guess. If your voltages are higher this would make the unit brighter and harder sounding than an original. And if your layout is flawed (even transformer orientation can make a difference) you could have a positive feedback interaction.  
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