Many thanks for your help !!! Really appreciate … I’m new with tube … so i’m like a baby 🤗
To everyone who is planning to test the repro amplifier. After performing more simulations, I found that values marked in below pictures are critical and cannot be changed. Please proceed with caution, as the design is not 100% verified.
Hi ... back to you, I've assembled the PCB preamp and the PSU, with the following voltage 250 / 7 / 12, I saw that the 7V version of the tubes is the PCC88 ... I've to get this one or I've to continue with the ECC88 ?!? Many Thanks
PAOLO
PAOLO
You can use either the PCC88 or the ECC88, but you can't mix them. All one or all the other.
Look for the 1R resistor on the PC board near the muting circuit. Just below it you'll see three holes for selecting the filament voltage. The power supply gives you 7 volts for the heaters. This is correct for the PCC88. Jumper the left hole and the middle hole and you'll get 7 volts. If you want to install PCC88/6DJ8's, you may jumper the middle hole and the hole on the right, or just omit the jumper completely. Then you'll have 6.3 volts.
Look for the 1R resistor on the PC board near the muting circuit. Just below it you'll see three holes for selecting the filament voltage. The power supply gives you 7 volts for the heaters. This is correct for the PCC88. Jumper the left hole and the middle hole and you'll get 7 volts. If you want to install PCC88/6DJ8's, you may jumper the middle hole and the hole on the right, or just omit the jumper completely. Then you'll have 6.3 volts.
One more thing to mention, picked up by another member, is that cathode resistor bypass capacitors (100uF/16V) on PCB are not to be installed, unless you have low gain from tape head and you have measuring equipment. If you install them you might get clipping. The repro amp was designed with input of 2.5mV or so.