Hello, new user here, I am restoring a 1960s Hohner Symphonic 310 Organ, and somebody took the reverb unit out of the organ, so I'm trying to find a replacement.
I was able to get the schematic from Hohner but they didn't have any info on the reverb unit.
I was wondering if it's possible to determine the characteristics of the reverb tank based on the schematic of the reverb amplifier?
the input transformer has printed Bv 30-68, don't know if that helps. I can provide the full schematic if necessary.
I was able to get the schematic from Hohner but they didn't have any info on the reverb unit.
I was wondering if it's possible to determine the characteristics of the reverb tank based on the schematic of the reverb amplifier?
the input transformer has printed Bv 30-68, don't know if that helps. I can provide the full schematic if necessary.
In the early days of reverb units, there were many patents and some used a system based on a crystal cartridge, others used what we all use now, a magnetic system, similar to a loudspeaker and moving cil microphone.
Looking at your circuit, I suspect the high impedance tank will be best for this product; Accutronics Reverb Unit 4DB2C1D.
Looking at your circuit, I suspect the high impedance tank will be best for this product; Accutronics Reverb Unit 4DB2C1D.
This will help:
https://www.amplifiedparts.com/tech-articles/spring-reverb-tanks-explained-and-compared
As Jon says the output impedance is high. As for the input I think you will need a rough guess at the transformer turns ratio. Drive the input and see the AC voltages at the input and output of the transformer say at 1KHz.
Goes without saying make sure it fits. You also need to decide on short-medium or long reverb. Many are aimed at guitars rather than organ. The output can be peaked (tuned) with a cap across the 10M.
https://www.amplifiedparts.com/tech-articles/spring-reverb-tanks-explained-and-compared
As Jon says the output impedance is high. As for the input I think you will need a rough guess at the transformer turns ratio. Drive the input and see the AC voltages at the input and output of the transformer say at 1KHz.
Goes without saying make sure it fits. You also need to decide on short-medium or long reverb. Many are aimed at guitars rather than organ. The output can be peaked (tuned) with a cap across the 10M.
A similar circuit was used in the Hohner guitar/accordian amplifiers of the time and all used a low input impedance tank i.e. an "A" or 8 Ohm.
Here is an example from the Orgaphon 75MH (MH= mit hall or with reverb)
I would also personally recommending using a 3 spring tank, or the "9" rather than a "4" as the sound is fuller which would suit an organ better.
Here is an example from the Orgaphon 75MH (MH= mit hall or with reverb)
I would also personally recommending using a 3 spring tank, or the "9" rather than a "4" as the sound is fuller which would suit an organ better.