Many years ago, I built a pair of the JE Labs 300b monoblock amps. In the power supply, I omitted the first capacitor after the rectifier, so that the choke is the first component. It results in voltages at the 300b plate of about 340V, and about 82V and 230V at the 6SN7 plate stages.
One of the amps has exhibited, more recently, a noticeable drop in midrange and bass output. The other one sounds fine.
Measurements show that the voltages are nearly similar between the two amps, the resistors all measure what they should (no irregular drift from their original values). There are no crackling sounds.
Where should I look next to diagnose this problem? Do the capacitors (coupling and cathode) cause problems like this?
Thanks
This post is made possible by the generous support of people like you and our sponsors:
Topic - Troubleshooting a JE Labs 300b amp - ddelaney 08:49:55 07/10/17 (10)
- RE: Troubleshooting a JE Labs 300b amp - GeorgePope 01:47:12 07/11/17 (2)
- RE: Troubleshooting a JE Labs 300b amp - ddelaney 09:30:55 07/11/17 (1)
- RE: Troubleshooting a JE Labs 300b amp - GeorgePope 13:38:32 07/11/17 (0)
- RE: "Do the capacitors (coupling and cathode) cause problems like this?".... - Ivan303 14:08:23 07/10/17 (0)
- RE: Troubleshooting a JE Labs 300b amp - Cpwill 10:05:59 07/10/17 (5)
- RE: Troubleshooting a JE Labs 300b amp - ddelaney 10:46:34 07/10/17 (4)
- RE: Troubleshooting a JE Labs 300b amp - Cpwill 11:26:40 07/10/17 (3)
- RE: Troubleshooting a JE Labs 300b amp - ddelaney 12:15:03 07/10/17 (2)
- RE: Troubleshooting a JE Labs 300b amp - TRUFI 10:22:26 07/11/17 (1)
- RE: Troubleshooting a JE Labs 300b amp - ddelaney 14:14:29 07/12/17 (0)